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Furuno LC-90 User's Manual

1. APA 6 CANADIAN EAST COAST 5930 APA 6 ICELANDIC 9980 0 oe 0 o APA 7 NORWEGIAN SEA OUST wae APA 7 MEDITERRANEAN SEA 7990 coer 8 LION CHAIN 5970 eT eee ae aras ee ee Cas LABRADOR SEA 7930 e APA 9 APA 1 bu GaLVWOLNY HOLINOW SI 5 W NM ONILLINSNYHL 2 56 x QN3931 put UNE L 021 M O8l NSS M amp OSI 69 2E I 8 N OS NIVHO DHIDVd TVULNI 95 906 EL 2esn 00062 4 2esn 9 OZ 00011 X ONVHOT AW130 3Wl1 XVW AVIA 3WJl NIW SIVA 1439530 OQIV 0H SI VWI OMI x gt N SWAP 96 114 WN X pus UNE L 682940 jo Sreujnosddy 3 081 Desn 9 67 98 oesn 9926 9 S sn pZ OI Er 88 96 6l AW130 1 Q031vWO4nv HOLINOW DNILLINSNVHI 3 02 GN3531 oesn 0006 oesn 000 S sn 000 Og 2esn 0001 XVW AV13Q 3WIl
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4. True Bearings Function 4 DV E SETTING THE AVERAGING TIME Function 3 HESS RO XR RM T FS AUTOMATIC ASF Function 4 s PN DIMMER ET EN RETTET SUMMARY OF BASIC OPERATIONS 11 10 10 11 11 13 14 15 16 17 19 20 20 20 24 26 26 28 29 29 30 30 31 31 INTERMEDIATE LEVEL OPERATIONS ENTRY OF A POSITION INTO A WAYPOINT Waypoint Entry by Latitude Longitude Coordinates WPT Mode Waypoint Entry by TD s WPT Mode 9 9 9 6 9 n lt 9 QR e 9 Q 9 9 9 9 9 6 o Waypoint Entry of Present Position EVT key in WPT Mode Waypoint Entry by Range Bearing From Present Position CLC Mode SELECTING WAYPOINT S FOR USE WITH OTHER MODES AND FUNCTIONS Selection of a Destination WP from Present Position NAV Mode ca Specification of a Pair of Waypoints From amp To NAV Mode RANGE AND BEARING CALCULATIONS R B and CLC Modes Simple Range and Bearing from Present Position to a WP R B Mode Range and Bearing Between Two Waypoints CLC Mode CROSS TRACK ERROR FUNCTION XTE Mode T VELOCITY TO DESTINATION VTD AND TIME TO GO VTD Mode ALARM FUNCTIONS ALM Mode Off course Alarm eevee eee esses Border Alarm ee ea e Arriva
5. The second method of specifying a waypoint position is by TD s This proeess involves converting the TD s to appropriate Latitude Longitude coordinates and then using those coordinates for the waypoint This sounds an involved process but the LC 90 makes it straightforward provided that the operator uses some degree of caution Baek in the section on How Loran C Works we stated that Loran C TD s form hyperbolie shaped lines and showed a simplified drawing Fig 18 We have reproduced that figure here to refresh your memory 34 You wil note that these umbrella shaped lines are symmetrical about the baseline between the master and slave transmitting station You might think of the baseline as a mirror where a TD line of position on one side has a mirror image on the other side of the line While it is true that for a particular Latitude Longitude position there is at least one set of two TD s that cross at that point it is also true that for any one set of two TD numbers there are two Latitude Longitude positions You ll probably have to think about that one for a while and look elosely at the drawing 3 28550 2854 28534 4 lt Z y xt uut Ts 4 f d MASTE INDIVIDUAL TD Time Difference Fig 18 What it all boils down to is that in order to convert set of two TD s set of Latitude Longitude coordinates you have got to be
6. CYC Indicator Function 6 If the MCYC Master Cycle indicator for the master or CYC Cycle indicator for either of the two slaves is on the LC 90 is trying to warn the operator that it may well have locked onto the wrony cycle of the Loran C signal All modern receivers track on the third cycle of the pulse The signal amplitude at this point is not terribly high so in weak areas the receiver might become confused and lock onto the fourth rather than the third cycle since the fourth cycle is stronger If this occurs on the Master signal alone the slave signals will be 10 microseconds lower and the position data TD s obtained will be in error by as much as 3 n m The LC 90 employs sophisticated mathematic algorithms to reduce the possibility of a 10 microsecond error caused by weak signals but if the shape of the Loran C pulse is distorted by passage over land or by reflection from other vessels or even from masts or conductors on your own vessel cycle locking problems could occur In the top line of the secondary Function 6 the LC 90 displays which cycle is tracked by the receiver 1 L _ _ E C 79 Fig 37 Function 6 Screen See Fig 37 010 is displayed at the left hand side of the top line The figures from left to right indicate the tracking points for the Master Slave 1 and Slave 2 signals respectively 0 indicates that the recei
7. Ship s power lines are notorious for being dirty electrically The voltage ean go all over the place as various heavy loads are placed on the line and the power wiring is a prime source for interfering electrical signals from Such sources as alternators or generators and other electronics equipment like radars or echosounders The LC 90 is a very forgiving machine since it has a built in universal D C power supply that can take input voltages from 10 to 42 V D C However a piece of gear of this quality deserves to have a circuit breaker dedicated to it alone The size of the wire feeding power to the unit should be no less than AWG 16 gauge 0 5 mm square Ground Connection No less important for proper operation is the ground for the Display Unit On a steel boat a good connection to the hull is sufficient On a wood or fiberglass boat it is best to use a ground plate mounted on the hull exterior if this is not practical the engine block can be used Do not share ground leads that go to other equipment in the console but instead run a separate heavy duty wire for the LC 90 alone Follow the drawing below for detailed wiring information To antenna d coupler z To auxilliary equipment plotters autopilot etc Black i cose 12 24 32V BATTERY Ship s bonding system Fig 11 metallic tanks engine block through hul metal fittings etc a a Ps
8. hitting the conversion key You can now watch as the unit settles down on the correct TD values for your area While the LC 90 is busy first identifying the master and slave signals it will flash the MCYC MSNR SNR and CYC warning indicators While it is acquiring and locking onto the signals these warning indicators will stop flashing When acquisition is complete in about 3 to 5 minutes depending on the quality of the Loran signals in your area all signal warning indicators will extinguish and the TD readout will be stable with perhaps only the least significant digit to the right of the decimal point changing randomly up and down a small amount Now call up the SNR function the 6 Function by first pressing the key and then the 6 key You should see a screen similar to the one below it gt C 5 a Fig 13 Function 6 Screen Io N The SNR for the Master and the two slave secondary stations automatically selected by the receiver are displayed on the left hand side of the third fourth and fifth lines respectively The maximum value for SNR is 99 and unless you happen to be in a very strong signal area it is likely that at least one of the stations being received will have an SNR value less than 99 It is important that you have at least one station whose SNR is less than 99 so that you can easily observe any small degradation of SNR as various interference sources on your boat are
9. x INDIVIDUAL i TD Time Difference simple system is shown in Fig 2 consisting of a master transmitting station and two slave stations This is the simplest configuration used In practice most of the chains in the world consist of three or four slave stations associated with each master Note that the lines drawn connecting the master and each of the two slaves are known as baselines To illustrate the basic idea behind the Loran C system let us take a simple case where the boat with the Loran C receiver is located on one of the baselines and is in the middle between the master and the slave If the transmitters were both to transmit simultaneously the time taken for the signals from the master transmitter to arrive will be the Same as that for the signals from the slave to arrive In other words the difference in arrival time will be zero If the boat is moved so that the time difference of signal arrival from master and slave is kept constant at zero then the plot of these movements will be a straight line halfway between the slave and the master stations This line will be perpendicular to the baseline The line of constant time difference is known as a Line of Position or LOP for short Other LOP s can be generated for conditions where the time difference isn t exactly zero and these LOP s will form hyperbolas rather than the straight line in our simple case Radio navigation systems such as Loran C a
10. INI s INS ae 9 7 s OSEE mit cen ial d ATT PRL OO HH vm gt Z AA U x Age O 95 ET sla S 2H 1 p lt Le __ lt ae a ied oe Dove tag br wa o LEIHO Z 1 8S T Adit lat C FOU EL Q RS zo T AHIL cL v2 T LJ Lu Id zU CIS ITS 8 ene gt Sse 18 EX idCd precem enel 3 S 3 A 8894 2S2 8 i i ERI X jg x DIE O 961 494 122 1 13 l 2 j u 111 x I I AZ SSH 1592952 8 I L LJ 77777 Tr 13NVd Lv3HM 13N Wd VIH PLIM 1 I gt Uv L zu Nx REN 572 40 28 71 APPENDIX REFERENCES CHARTS OF VARIOUS LORAN C CHAINS SHOWING RECOMMENDED re ee te M M a m e TD PAIRS List of Contents NORTHWEST PACIFIC 9970 APA 2 CENTRAL PACIFIC 4990 APA 2 NORTH PACIFIC 9990 APA 3 GULF OF ALASKA 7960 APA 3 CANADIAN WEST COAST 5990 ecooeeeceveeceee 4 U S WEST COAST 9940 cese eee eo oes 4 SOUTHEAST U S 7980 ecocos sss APA 5 NORTHEAST U S 69960343 E VOCE COOPER RACES Pa APA 5 GREAT LAKES 8970 ee eo o
11. cycle M DESCRIPTION Normal aquisition tracking attainable It may not acquire signals or even it once acquired might lose tracking easily Fig 38 In Function 7 if you override the SOUND OF function on line 1 to show Sound On use the key followed by ENT you can use the audible SNR function In addition to the visual SNR readings shown on the display the duration of the beeps emanating from the buzzer indicates SNR quality The shorter the duration and the longer the time between beeps the poorer the indicated SNR is You might use this function while remotely trying various antenna positions MAG V rnit rnc 5 LULlnaui Lift of H Hil OLLO Fig 39 Function 7 Audible SNR Table AUDIO TONE INTERVAL 9 to 20 20 to 30 30 to 40 40 to 50 50 to 60 60 70 70 99 BLINK Indicator If there is a problem at one of the transmitting stations it will begin to transmit a warning indication called Blink The LC 90 responds by producing a blink indication that tells the operator which station is having problems If slave 1 is faulty the blink indicator BLK will come on at the far left hand side of the top line if slave 2 is faulty the blink indicator BLK wil come on at the far left hand side of the second line and both blink indicators will come on if the master station is faulty In
12. wireways and it may have to be removed and reinstalled later after the antenna cable has been routed through the boat PIPE 26 2mm When a 4m whip antenna option used in fringe reception areas is used its installation should be as in the drawing below Note that the coupler is not designed to withstand the strain of such a large whip directly Instead a mounting plate for the 4m whip must be provided with a wire to the antenna coupler from the bottom of the whip ist Dr EN S CONNECTOR KE FEEDER COUPLING BOLT LOV 1010 4m WHIP ANTENNA 10 SW SUS A jo AY ANTENNA COUPLER m rM Th il 1 ANT COUPLER MOUNTING MAST 940 80 1 PLATE Ht a _ 230m 9 x 1 30mm 5 1 pun HOSE CLAMP ENHE 24 9 U BOLT Fig 8 18 Display Unit Installation Locate the Display Unit in a position where it can be viewed and operated conveniently but where there is no danger of salt or fresh water spray or immersion The Display Unit is mounted in a trunnion mount The mount itself be installed either overhead on a bulkhead or on a tabletop The drawing below gives the recommended clearances and the mounting dimensions for this unit You can use the mount itself as a template for locating the mounting bolt holes As was stated before make sure you allow enoug
13. zn 9 7 6 Cp oesn 000 or J N 15 05 1S3M S 2esn gz ccG Cv osn 000 If 7 esn 681 62 esn 000 Z oesn 2 1 8 OE 2esn 000 2 A 2Sesn g c6g 9 2esn OOO SIE M 2esn 7 99 SI 2esn 000 1 X AV1I30 SWI AVIC 3W l1 NIW JWL XVW AVIZO JWL 131YWOLnV HOLINOW YOLINOW ONILLIWSNVUL ON3931 _ 21 ogy ASI Z OSTV OF66 NIVHO 1S3M S fi 350 310N NIVHO 1SVOOD 1S3M J9 NVHOT N SE N Ot N Sv N OS o APA 4 2 1 HOLINOW H2V38 VNI1OHY2 HOvV38 wuaLiant 13XONINVN X ONILLINSNVHL 37 11AGNOWAYY gt M QN3931 JTUAZONVED VO3NIS W 08 oe 3NO1VW SWHPZ X96 Assonsev Xii WN X _ e SWHPZ X90 xid WN Y put UNS E S0009 pue LING L 8064840620 mwy Sauro 08 MOL CA M 6 0966 NOY 75 11 0966 NOS wt S sn vp 690 9 poC ec t ean a S N 1SV3HLHON oesn 91 50 19 QOC ev E 25e 5 s n 937666 8 00058 X NVHOT Deen QUO IL 2937 106531 225r 000 11 AVA3 wL 1 NIW AV130 3NIL XVW AY130 JWL NIW N06 HOLINOW YOLINOW ONILLIMSNVHI QN3931 5 unoa8uvH XOd Z HOLINOW Gp
14. 11 49 60 0 19 minutes South and 10 33 seconds East 10 33 60 0 17 minutes East remember the LC 90 uses tenths minutes rather than seconds WORLD GEODETIC SYSTEM DATUM ADJUSTMENT ploce this chart WGS 72 Datum shift olf porallels 11 49 seconds South ond all meridians 10 33 seconds East 59 1 Get into Function 2 by pressing followed by 2 You should see a display similar to the one below The previously used offset values are displayed on the readout the offsets will be zero is they haven t been specified previously Fig 43 Function 2 Screen The page identifieation number is displayed on the left hand side and the offset value for Latitude is on the right hand side on the top line The offset value for Longitude is displayed on the second line The GRI and slaves where the corrections will automatically be used appear at the left hand side of the lower three lines as shown in Fig 43 As explained previously these values GRI S1 and 52 are important for only when the boat enters the exact area bounded by these values will this page of corrections come into effect automatically Specify a page identifieation number and enter the offset value for Latitude on the top line If you want to enter TD corrections instead of L L corrections you would skip this step and go on to the section for entering TD corrections For example an identification page No 09 two digits and a correction of 00 19 mi
15. TESTING AFTER INITIAL INSTALLATION The best way to check for the adequacy of an installation and for the presence of noise aboard the boat which might hamper Loran C reception 20 is to use the SNR Signal to Noise Ratio function in the LC 90 itself Make sure all electrical and electronic machinery on your boat is turned off before starting this test This includes the engine and any auxiliaries as well Before plugging the power connector into the back of the LC 90 recheck the polarity of the DC using a voltmeter Then plug the power connector into the back of the unit Don t worry in the following procedure that you might not understand exactly what is going on the details will be explained later in this manual For now you just want to be sure that the installation is good enough and free enough from external interference so that you can run the LC 90 through its paces and learn how to use it later 1 Turn on the LC 90 by pressing the key while simultaneously holding down the key This will clear the internal memory completely and will allow the unit to initialize itself for your geographie area Continue to hold the CLR key until two distinctive beeps of the buzzer are heard The LC 90 wil then automatically go into its Initialization function 1 and will be ready to accept the approximate Latitude of your present position You must know and enter your latitude within a tolerance of one degree from the true position For the
16. gt x gt 0266 HD NIVHO DiHID2Vd LSAMHLYUON J NVHOT APA 2 WOHS d3LVWOLNY HOLINOW 3499 MOYYYN X YOLINOW W SINHPZ 56 Xid WN X ON3931 UNS 28820403 JO 6 jut MeStel Most M OS NSt MSGI gt WM OS o NIVHO VXSYTV 40 TIND J NV HOT gz eoc lt 2 5 000 92 2 _6 609 9 0001 x AV130 JWL xvW AVI3O NIW Pus E oesn 6 0 oesn 6 15 1 G MOUHVN 2 Q31vWOLnVv HOLINOW 39N3HV12 140 YOLINOW DNILLINSNYHI invd is p QN3931 MOS MESI j SWuRZ xog ssmesy xij BP 0665 IH9 NIVHO H LHON NVHOT esn 000 t 2 5 000 EZ 2esn G 0c 8 Desn 000 Av130 Shi 81 OS sa nee gt lt gt PA AWISC 3A 1 NIM APA 3 LH9I1H28V3S A GALVWOLNY BOLINOW a AQUVH 1404 Z NMOLYYOCIN X HOLINOW 394039 A DNILLINSNVHI 6 TAOS IORS X NOTIVi W JAVI SWVITTIM W s Hir iid Gel SWuPZ X98 Assmasw xid WN X put 1 D i VHS C 06040409 MSO N GZ N O 4 NOt OSTY 0665 15909 1S3M 350 3L0N WHO a
17. i TO BE PREPARED LOCALLY i EXT BUZZER eae TEE RIT eg Lipi PKPS 3 39 CODE No 000 103 773 D cg OR EQUIVALENT pe LORA Q PNP amp fe gt 100 DO N ARMOR 254495 OR EQUIVALENT 3 tb 12 VDC NAV LC 90 NOTE USE CABLE CO SPEVV SB C 0 2 5 Xe CONNECTOR PLUG FACTORY WIRED 3 TWIST PAIR X4 GROUND ARMOR THRU CONNECTOR CLAMP 5 GROUND THRU CABLE CLAMP COLOR VIDEO PLOTTER 2 PLOTTER T T2 HI0P SHF AA m S rt Jor 72 Hi0P SHF AA rex ox Pi 1699 FP 70 FP 70 W IF 5001 Tus Panem IF 5000 AT I e PRINTER NI GND INTERFACE x ne a LP SRCW6A 6 0P in RD 100 101 Pars gt SAT NAV UN by W L ROM BOARD J 5o 13P 4105 REMOTE DISPLAY 2 SRONGAIE 10P V ropes Pii 44 ta 1 1 ic d 0 P COURSE C COURSE 3 PLOTTER PLOTTER n FP 300M x 6 15 LEAD WIRES FITTED SOLDER IN FIELD CUT UNUSED WIRES 7 LOP S LINES NOT PLOTTED CONNECTORS NOT SUPPLIED AS STANDARD 9 OPS amp L L PLOTTED Fig 14 INTERCONNECTING DIAGRAM FOR LORAN C NAVIGATOR LC 90 PERIPHERAL EQUIPMENT 25 BASIC LEVEL OPERATIONS TURNING THE UNIT ON AND OFF Press the key After several seconds during which time the LC 90 will be performing an internal self check the display will activate If an error should be detected during
18. key and then type in the desired Waypoint number followed by ENT For example let s say that you want to observe the position stored in Event memory number 05 and that you then want to transfer that data into Waypoint number 59 The touchpad sequence would be as follows 1 Get into the Event Function 40 by hitting the key followed by 0 2 Hit 3 Hit 9 4 Now verify that Waypoint 59 actually contains the Event data by accessing the WPT Mode and calling up Waypoint 59 Storing Present Position into Waypoint Memory EVT WPT Mode When you press EVT in the WPT mode the present position will be recorded into the waypoint memory number you have specified has been already deseribed Put the LC 90 into the WPT Mode by using the left or vight arrow keys to move the Mode indicator arrow to line up directly over the label The cursor will be flashing on the third line Hit the CLR key specify the waypoint number into whieh you want to store present position and then hit the key Make sure that you are in the Latitude Longitude format in order for this function to work properly Now you can press the key Note that your present position has now appeared on the bottom two lines of the display CONVERTING COORDINATES WPT Mode The LC 90 enables you to convert position coordinates from TD format to Latitude Longitude format and vice versa in the WPT Mode First get into the WPT Mode using the left or right
19. 44109 AeK L L BUM NMI UL C 0 71 ui h LLLI 49141504 44959 14 UC FC Otu O4 36333 Y28244 550249 OL WOM4 SoM 40141504 408581g 955109 diys peeds S lus Cn 2 Sim U OL WOU 4 SoM 2 L Ls 40141505 u s iuo L 14 oui 404 UO111SOd u03110q o do 01 1391 0 pue 6 nay Jo paoetd sueeJos uonounj ji ds sueeJog uorjoung SA uO 42unJ gM ON 1 25 NNSi1uIOg Bul ysesy 1 uNS 1U1Og 6 6 jpeubls Aouen eJ j n 3 Pa dE e t uolj5unj bej4 Buiun LOU WYYNS U10q vo 42unj epow 1n Li PIOH 9944 pe42e eS 494114 5 TEF SN4e4S Q24ON I r 1 230 UNS 7 LI L ji 5 ON 94114 u24ON 25 093 2 UNS 2s H G 25 401426195 1949 25 TUE zi ZS JO Sy 18 003 1S NS is E 5 1875819618189 E TEE IS 20 enieA jsy m is B o ok 5 1 452413 51424 jSy 73 Ug Uh ced on eA Bew o drum LES M RTT enims A TONE LI go ADYW 35 epo 75 epoo 25 1 uJ04 e4e0 Z 4ndjno GL epe IS epo IS uoI 42un4j UOo 42Un4 49 4 UJOj
20. C TD overlays Many commercial fishermen with their hang logs in TD s will find that it is a good idea to write down the corresponding Latitude Longitude coordinates next to their older TD information when they make a TD to L L conversion while entering specific positions as waypoints See the Advanced Level Operation section for a tip on how to enter TD s as waypoints while still retaining the advantages of automatic ASF compensation The other methods will be used during a voyage when you want to record an interesting place instantly such as for example a good fishing spot you happen across Now before you actually start punching in numbers take a chart of your area and choose a buoy or some other position you know and write down on a seratehpad the Latitude and Longitude coordinates for your waypoint Using divider measure the distance from your present position to your waypoint and then write that down Now measure the magnetic bearing from your present position to your chosen waypoint using parallel rulers and write that information down What we will be doing is comparing the numbers you have derived for Range and Bearing with those from the LC 90 32 Waypoint Entry By Latitude Longitude Coordinates WPT Mode Entry of a position into a waypoint is a two step process First you assign a number to identify a particular waypoint and then you enter the desired position into that waypoint The LC 90 has one hundred waypoints
21. There are nine pages of offset information that may be stored in memory 3 This is the Averaging Time Function The operator may choose the amount of smoothing time constant to be applied to the L L and speed display The type of output data available at the rear panel for external devices such as plotters or printers is specified in this Function as well 12 4 This is the automatic ASF Additional Secondary Factor and automatic Magnetic Variation Function Both Functions may be disabled manually The amount of ASF correction automatically used by the LC 90 in the present geographic area is displayed Note that at 0 degrees variation True North referenced bearings will be obtained 5 This is the Cycle Selection Function The amount that the tracking point is ti be slewed manually is entered in this Function 6 In this function the SNR Signal to Noise Ratio and ECD Envelope to Cycle Difference are displayed These numbers give the operator an indication of the quality of the incoming Loran signals The display shows which cycle of the Master and two secondary stations the LC 90 is presently tracking and shows in addition the deviation of the internal reference oscillator from the ideal frequency 7 This Function is the SNR Visual Audio Indicator It allows the operator to make trial adjustments for example of the antenna location while watching the display or listening to the LC 90 buzzer remotely The tracking point for t
22. and after entering new data the blue key standing for Enter will be pressed The cursor will automatically advance to the next line where data may be entered after the key is pressed Note that if you accidentally type in the wrong data or if you hit the wrong key you may hit the key followed by to retrieve the data stored previously The following list shows a summary of the primary operating Modes and the secondary Functions of which the LC 90 is capable of showing SUMMARY OF MODES AND FUNCTIONS Primary Modes Data Readouts S C Speed Made Good and Course Made Good together with present position in L L or TD s at the discretion of the operator and the Route and or Waypoints in use 11 VTD Velocity To Destination in knots and Time to Go in Hours and Minutes again together with present position and Route and or Waypoints in use R B Range in nautical miles and Bearing in degrees Magnetic or True at the operator s discretion from present position to destination waypoint again together with present position and Route and or Waypoints in use XTE Cross Track Error in nautical miles off the desired track with arrow indieators to show direction of offset and direction to steer to get back an track As usual present position and Route and or Waypoints in use are shown Course offset in degrees and Range to destination waypoint are displayed as well Primary Modes Data Entry NAV This is the N
23. arrow cursor keys Select an empty waypoint memory number i e one where the L L is all zeroes If you try to make a conversion using a waypoint that already has data stored into it you will lose the earlier information completely Note also that the TD s you enter must be the same as the slave TD s actually in use by the LC 90 and that the GRI must be the same as the one presently in use For example assume the GRI is 9940 and the two slaves in use are the 27 and 43 lines We want to convert the following TD s to L L 43156 7 and 27245 9 microseconds 1 Call up the WPT mode 2 Select an empty waypoint number a waypoint where the L L is all zeroes on the third line 3 Press TD lt gt L L to change the position display to the TD format if necessary 91 4 TD1 on the fourth line 6 5 TD2 on the bottom line 4 6 lt gt L L to perform the conversion To convert L L to TD s specify the desired empty waypoint number type in the desired Latitude and Longitude while in the L L format and then press the TD L L 1 Key Note that the LC 90 stores all waypoints as L L positions rather than TD positions The conversion between L L and the corresponding TD s thus may be a little bit different from measured TD s perhaps as much as 0 1 microsecond This is the result of normal computational accuracy due to rounding off of numbers in the internal cal
24. careful that the waypoint into which you want to put the new information is empty before doing this operation Otherwise a waypoint with desired position already entered into it will be overwritten instantly and you will lose any information you may have wanted to keep Before calling up the CLC Mode look at the target waypoint to make sure that the L L stored there is zero zero by using the WPT Mode Assume for sake of illustration that your present position is 37 degrees 38 91 minutes North latitude 122 degrees 24 01 minutes West longitude in San Francisco and that you have found an interesting target on your radar with a range of 3 4 n m and a relative bearing of 135 degrees off your starboard bow The magnetic compass reading at the time is 46 degrees The target of interest is thus at a bearing of 46 plus 135 degrees magnetic or in other words a magnetie bearing of 181 degrees We assume now that your LC 90 is set up for automatic Magnetic Variation operation Let s put the position of this target into waypoint 32 First get into the CLC Mode 1 the desired To waypoint on the third line where at this time the cursor is blinking waiting for data entry CLR 2 ENT The eursor will automatically advance to the next line 2 Type in the range of 3 4 n m and 181 degrees magnetio using the folowing keystroke sequence CLR 0 3 4 ENT Range 3 4 n m Bearing 181 deg mag The result will be display
25. figure below for a typical display screen ASF 22 CLC Mode Sereen 40 CROSS TRACK ERROR FUNCTIONS Mode On a voyage between a starting waypoint and a destination waypoint the desired course between the two positions is known as a track It could just as well be termed the intended track because although it is the intention of the user to follow this course faithfully in reality he never can do so perfectly The forces of wind waves current and even steering errors or boat loading imbalances and propeller Speed mismatches on multi serew boats ean combine to throw the vessel off the desired track Of course a sailboat has an even tougher time sticking to an intended track since it must constantly tack to move in Spite of the wind direction We ll describe another function the VTD Mode later which is designed to help the sailboater achieve maximum efficiency in spite of the vagaries of the wind The amount which the boat is thrown off the intended track is termed the Cross Track Error often abbreviated XTE The angle of offset from the intended track due to eurrent wind and other factors is referred to as the Course Offset The LC 90 is capable of calculating the offset necessary to get back on course to your intended destination Note if whatever was causing you to be off course in the first place remains in effect there will be a continuous series of commands to change heading to get back on cours
26. into which position information may be entered These are numbered from zero zero to ninety nine The LC 90 allows you to look at the position already stored in each numbered waypoint by specifying the waypoint and then using either the L L or the TD format to read the stored position Some people might search through the waypoints already stored in the unit in order to find an empty waypoint in whieh to insert new information However it is probably less confusing to insert data sequentially starting at waypoint one and proceeding upwards one by one in the sequence that the waypoints wil actually be encountered on the voyage Obviously it s important that you write down your voyage plan in your log so that you have a permanent record of which waypoint is which Some operators prefer to reserve Waypoint ninety nine as a sort of Seratehpad so that any interesting position information they might for instance hear on the radio may be entered at the moment it is heard Any position data that have been stored in other waypoints thus will not be disturbed or even lost in the heat of the moment Waypoint 00 is a special one It is reserved for use when your present loeation is used in a navigation calculation This will be explored in more detail later Coneeptually waypoints are best thought of as being Waypoints From a desired origin or as Waypoints To a desired destination Several navigation funetions that will often be used in plan
27. investigated one by one If at least one station exhibits an SNR lower than 99 you may proceed to step 4 below Before doing that however write down the SNR values for the three stations preferably in the back of this book so that you will have a permanent record of SNR values Otherwise go to step 3 below first In the extremely unlikely situation where all three stations have SNR s of 99 go back to function 1 by pressing the key followed by the key Look in the appendix at the back of this book for the chart that describes your geographic area You will note that any particular area has two slave secondaries associated with it that are the optimum ohoices However most Loran chains have other secondary stations available that do not represent optimum choices usually because they are far removed from that area and thus would be rather weak in signal strength In the case of our San Francisco example the optimum slave secondaries are the 27 and the 43 secondaries However there is a third secondary station in the chain the 11 station and it is located in Washington state far from the San Francisco area and hence probably rather weak Again you shouldn t worry at this point that you may not know exactly what these mysterious numbers mean just note the two digit value of the other secondary stations that the Loran chain is capable of providing in your own area of operation 22 Going back to our example if the Master and th
28. key is pressed the level will ehange in the above sequence NUMERIC KEYS There are eleven numeric touchpad keys and these are orange in color The keys O0 through 9lare employed to enter all numeric data The key is a general purpose key that is used to change from North to South latitude or East to West longitude when entering data for Modes or Functions requiring Latitude Longitude data and which is also used to change default values for many Modes and Functions that can be used either automatically or manually This key is also used to turn on off many functions In each Mode or Function where data may be entered leading zeroes must be specified for ex waypoint 01 must be entered fully rather than as 1 LC 90 will reject entries it cannot understand where leading zeroes haven t been entered Trailing zeroes needn t however be entered fully For example a latitude entry of 37 degrees is just as valid as tne ful entry of 370000 degrees 10 OPERATING MODE FUNCTION SELECTOR KEYS The four blue keys on the lower left of the keyboard are the Mode selector keys The two arrow shaped keys select which one of the nine Mode screens is in use Pressing these keys causes the Mode indicator arrow to move sideways to align itself above the labels for the operating Mode on the panel beneath the LCD display The readouts on the LCD itself will change in accordance with the Mode selected Pressing the left arrow when the mod
29. mode exeept for the WPT Mode The stored position is automatically put into Event Memoey number 01 and any earlier EVT positions are shifted upwards by one nuinber What was earlier in number 91 will thus shift up to number 02 When there are 10 Event numbers already stored in memory putting in another one will cause Event number 10 to be overwritten by what was previously number 09 You may call up the stored position by using the secondary Function 0 Press followed by 0 and the Event display wil appear as shown in Fig 35 Fig 35 Mode Sereen Select the event number you wish to display and the position data for that Event number wil appear on the bottom two lines The LC 90 allows you to transfer the data from an event memory number to the waypoint memory if you want to You need only specify the waypoint number where you want to data from the Event memory transferred Be careful here Any data that is already stored in the targeted waypoint will be automatically overwritten when you do the transfer It is advisable to 90 an Event Memory to make sure it is unused Select the desired event number on the second line by first pressing CLR and then typing the desired Event number two digits long followed by Then select the Waypoint number into which you wish to transfer the data from the Event number The cursor will automatically have moved down to the third line after you pressed the key You would now press the CLR
30. of the world have not been measured as of this time To activate the automatic ASF compensation you must call up the Function 4 by first typing followed by 4 As with all the Functions it isn t necessary to use the key after typing in the 4 You should now see a screen similar to the one in Fig 16 where the cursor wil be on the A since it is flashing This is the Automatic Variation function You will need to hit the down arrow key twice and hit 30 followed by You should see the OFF indication next to the label ASF change to On If your geographic area is one of those that have ASF compensation values tahulated for it after less than about 2 minutes of computations you will see the values of TD offsets that will now automatically be factored into the L L computations If your area doesn t have any ASF compensation values available the ASF indicator that has now appeared on the top of the display will blink Otherwise this indicator will be steady indicating that automatic ASF compensation is in effect Note that the ASF compensation values programmed into the LC 90 are the average values for a 1 degree by 1 degree grid If for some reason you need more accurate compensation values you will have to enter these manually This procedure will be covered in the Advanced Level Operation section later in this manual Meanwhile go back to any of the Modes showing present position Modes S C VTD R B XTE WPT CLC an
31. or 50 nautical miles whichever is greater Loran C system accuracy is often capable of providing a reliable fix within 30 meters of one s actual position but more typically accuracy of about 100 209 meters is possible throughout the coverape area However system repeatability that is the ability to return to the same spot consistently is usually on the order of 20 30 meters Quite often it is even better than that Basic Navigation The essential idea behind a scheme of positioning on the globe is that any particular point on the earth s surface can be uniquely described by the intersection of two lines Latitude girdling the earth horizontally laterally and Longitude girdling the earth vertically Examine the section of chart shown next page Fig 1 depicting an area off Yokohama Japan One see the parallels of Latitude running East and West horizontally and the meridians of Longitude running vertically North and South Overprinted on this chart are so called Loran C Lines Of Position or TD s Time Differences as they are more commonly known We ll get into why they are called TU s later suffice it to say for now that a Loran C receiver will give you these numbers and that you can use hese numbers to find your position Note that the TD lines run at a variety of angles with respect to the lines running North South or East West They are in fact actually curved lines segments of hyperbolas but this is difficult to see
32. procedure to Disable the automatic process Now the LC 90 wil begin searehing for the master and slave stations to verify the present approximate position you just entered The display will show 9999 for the GRI and 99 for both slave stations The MCYC MSNR SNR and CYC signal warning indicators will flash at this time After about a minute these warning indicators will cease flashing and the appropriate GRI and slave secondary TD numbers will appear on the fourth and fifth lines typieal Function 1 is shown below MAG V ASF 313980 1 CCCOHU 9g 59605 2n r S1 w cl 52 Fig 15 Function 1 Screen 27 Note that the secondary stations are represented by the first two digits of the appropriate number of microseconds You may wish to look in the Appendix A in the back of this manual to assure yourself that the unit has chosen the correct GRI and slaves for your area You should now go back to the S C Mode to observe the receiver while it is locking onto the Loran signals Press either the 4 or the left or right arrow key to exit Function 1 and then press either one of these keys until the Mode indicator arrow is lined up over the S C label on the front panel under the display Now press the TD L L key to watch the TD s change while the unit is locking onto the Loran signals After acquisition and locking is complete all the signal warning indicators will be extinguished and the T
33. sake of illustration assume for now that you are located near San Franciseo and that your present position is approximately 37 degrees North latitude and 122 degrees West longitude Enter the following keystrokes Entering initial Latitude Function 1 The flashing cursor will automatically advance to the longitude line and here you would enter 2 ENT Entering initial Longitude Function 1 Note If your present location is in the Southern latitudes or the Eastern longitudes you will need to override the default North and West hemispheric values by pressing the key The cursor will automatically place itself on the next line and the A on that line will flash For now we will use the automatic GRI and slave selection function Wait for less than approximately 120 seconds to see what the LC 90 decides as appropriate values In our San Francisco example the unit would automatically come up with a GRI of 9940 and with slave selections of 27 and 43 You needn t worry about what these numbers mean at this point Simply go on and leave Function 1 by hitting either the left or right arrow cursor keys Now press the left or right arrow cursor key until the indicator lines up over the S C label You should see displayed a screen similar to the one shown below MAG V 1384 n Rit CIJ L E S L Lh Fig 12 S C Mode Screen 21 2 You may wish_to watch the receiver go through its acquisition sequence by
34. settle down with all numbers and indications stable before proceeding on to any other Mode or Function Waypoint Entry of Present Position EVT key WPT Mode There are times when you will want to store your present location into a waypoint For example you might have come across a particularly good fishing spot and want to record it as a waypoint so that you may return to this location at a later date The procedure is simple first make sure that you are in the L L format and then get into the WPT Mode Then specify the waypoint number into which you want to store the present location Now hit the key You will find your position has now automatically been stored into the waypoint Obviously this requires some caution on your part The infor 36 mation stored in a waypoint will be overwritten when you press the key Check to make sure that an existing waypoint is empty before hitting the key unless you don t mind losing old information Waypoint Entry by Range Bearing From Present Position CLC Mode The LC 90 provides for waypoint entry by using Range Bearing from present position in the CLC Mode The calculated position from the range and bearing you have entered are displayed in the upper two lines and stored into the To waypoint selected in the third line You will see the N S E W hemisphere indicators flashing in the CLC Mode to warn you that the L L shown is not your present position You must be very
35. the cursor will advance to the next line where you may select the autopilot output format Many modern pilots are designed to interface with a Loran C receiver that produces the NMEA 0180 simple data format In the future it is expected that some autopilots will be able to use the more complicated NMEA 0183 complex format For now though if you want to interface your compatible pilot with the LC 90 you would select the 0180 format on the fourth line to show 180 and then press ENT P 64 Fig 45 Function 3 Screen TUNING INDICATION Function 8 The LC 90 provides a Tuning Indication in secondary function 8 moinitoring the signal strength in frequency range between 70 and 140 KHz The chosen frequency is shown on the display and the signal level is indicated by a series of bars Get into Function 8 by pressing and 8 The frequency selected is displayed on the third line next to Fr To change the frequency push the A and W arrows The number of bars appearing in the three lines above Tune vary according to signal strength Twenty bars indieates maximum signal strength TROUBLESHOOTING Self Check 1 As already described the LC 90 carries out its self check automatically each time power is turned on If tne self check sequence detects a failure on the CPU board an error message ro 1 2 PA C xxx or C2 x will be displayed x in the preceding messages stands for a digit of some sort If
36. want to shift the tracking point of the 52 secondary 20 mieroseeonds higher you would enter 20 0 on the bottom line after CLH ing that line Manual Notch Filter Setting Function 9 Loran C receivers are vulnerable to interference in the region of 60 KHz to 140 KHz coming from sources such as Decca chain transmitters or military low frequeney communication transmitters The LC 90 contains six notch filters to notch out and eliminate such interfering local signals Normally these filters are used automatically since they will seek out and notch offending signals very accurately all by themselves There may be very rare occasions when you may wish to noteh out an interfering signal manual To do this you must know the frequency of the interference For example there is very strong military transmitter operating on the frequency of 88 KHz in the mid Atlantic region of the U S This transmitter can cause problems when a vessel comes close to its location near Annapolis Maryland In this ease it may be necessary to put two notch filters on the same frequency of 88 KHz in order to knock down the level of this transmitter sufficiently for the receiver to operate properly To tune or disable a noteh filter manually use the following procedure 1 Press and 9 Filter numbers are displayed on the top line in the secondary function 9 See Fig 41 When the unit is first turned on after 57 installation six A s are displayed on the sec
37. waypoints is usually selected in advance and a Range Bearing calculation is made to get the heading to use for the first leg of the voyage As you approach the first waypoint you then will want to calculate in advance the next heading to take in order to get to the second waypoint after you round the first one To do this you will need to use the CLC Mode in the LC 90 The procedure is straightforward In this Mode you needn t respecify the waypoints presently being used by using the NAV Mode Instead you may make this calculation offline to use some computer jargon without affecting normal operations of the LC 90 which may have been navigating between two waypoints already previously selected in the NAV Mode You wouldn t want to change the present voyage parameters in order to do a planning ealeulation Let s say that you are presently traveling from waypoint 56 to 57 selected in the Mode and that you want to determine in advance the heading to set into your autopilot after you round waypoint 57 on the way to the next waypoint 58 1 First get into the CLC Mode using as usual the left or right arrow keys to line up the Mode indieator arrow over the CLC label The cursor will automatically place itself on the third line 2 Now key in the following From waypoint 57 to 58 You will now see the Range and Bearing for the voyage from waypoint 57 to waypoint 58 displayed on the fourth and fifth lines respectively See the
38. 4 0 1 4ndjing uor 42un4 Is9 9pou uoj4296 6S 139 40141504 9 594 eur 4877 15 INSTALLATION As was pointed out in the Introduction to this manual this machine can only do its intended functions if it is installed properly GENERAL MOUNTING CONSIDERATIONS The LC 90 consists of two units the Display Unit and the Antenna Coupler Unit The Antenna Coupler has been designed to withstand all the rigors of the marine environment and if installed properly is thoroughly water proof The Display Unit is carefully constructed to be able to withstand the humidity and corrosive atmosphere common in a pilothouse but it is not designed to be used outside directly exposed to the environment water spray or even coffee spills will most assuredly cause damage to the sensitive components inside Keep these factors in mind when planning the installation of the Display Unit Many owners will undoubtedly use the LC 90 on small boats many with center consoles The Display Unit must be mounted inside an enclosed cabinet completely shielded from salt water spray and from fresh water spray if the boat is usually hosed down after a day s outing Corrosion can occur especially on the rear connectors exposed to salt spray unless these are taped and thoroughly sealed with putty compounds made especially for this purpose Most small center console boats are equipped with such a
39. D readings will be stable You must always remember that the unit is not ready for navigation until these signal warning indicators are extinguished These indicators will be fully explained in a later section of this manual The acquisition process will take between three and five minutes depending on the quality of the Loran signals in your arca Switch the Latitude Longitude display by pressing the key again Note that the L L readout is stable and that your position is displayed in degrees minutes and tenths of minutes not seconds Check the LC 90 s position with that shown on your chart It normally should be reasonably close but while you are in port the position may be as far off as a quarter mile or so because of signal distortion caused by passage of the signals over land nearby Don t worry things will get more accurate once you are out of harbor However it is still good idea to check your TD numbers against those from a nearby vessel and with your chart to ensure that the unit has locked onto the correct point of the slaves and the master signals and that no strange things have occurred during the acquisition process It is well to remember that the TD lattice printed on a Loran C chart is adjusted before printing to compensate for warping of the grid because of ASF Additional Secondary Factors and that TD s plotted on such a chart are thus inherently more accurate than the Latitude Longitude calculated from TD s In ot
40. EATURES The LC 90 has a large variety of functions all contained in a rugged die cast aluminum case that is compact enough to fit almost any size of boat Sealed membrane touchpads provide positive splashproof control of all functions displayed on the large five line LCD Liquid Crystal Display display Both the touchpads and the LCD display have variable backlighting for nighttime operation and touchpad operations are confirmed by an audio tone The LC 90 features virtually hands off automatic operation once it has been initialized for a specific gcographic area since selection of the proper GRI and the optimum slave secondaries is automatic as is ASF compensation Additional Secondary Factor for accurate Latitude Longitude readout automatic Magnetic Variation for magnetic bearing readouts and six automatic notch filters to eliminate interference Each automatic function however may be manually overridden if the operator desires Entry and readout for all position functions may be by either Latitude and Longitude or by TD s Time Differences for maximum flexibility Navigation functions built into the LC 90 include e Position readout in Latitude Longitude or Time Differences TD s e Speed Made Good and Course Made Good e Velocity To Destination and Time To Go to destination e Range and Bearing to a waypoint and Range and Bearing from waypoint to waypoint Bearing can be either True or Magnetic with automatic Magnetic
41. GO 9 O 0 0 0 9 6 9 9 9 9 P 9 OG B 9 OPERATING MODE FUNCTION KEYS E 88909 9 b 0 5289292992059 KEYS EE P 0 O 9 99998 8 e 9 9 9 9 q 9 9 9 o 9 Q 9 q 9 as SUMMARY OF MODES AND FUNCTIONS Primary Modes Data Readouts Vs Ed eR M RN 63 83 Primary Modes Data Entry Swed ok wees Secondary Functions eee Cr ree I Typical Mode Screens 6 s s Typical Function Sereens toeseseese TET INSTALLATION GENERAL MOUNTING CONSIDERATIONS ws DETAILED INSTALLATION INSTRUCTIONS Antenna Coupler unit Installation OE UA A Display Unit Installation 4 4 curses rr x rae Power connection esvvescvesercvceseves OTT Rcs e aa a Ground CONNECTION S Uaec TURIS UTE TESTING AFTER INITIAL INSTALLATION SEES es Mrd sss Teor a a HOW TO COMBINE WITH AUXILIARY EQUIPMENT BASIC LEVEL OPERATIONS TURNING THE UNIT ON AND OFF TESTE TCC LES ECR Ree ee eee INITIALIZING THE NAVIGATOR FOR YOUR OWN GEOGRAPHICAL AREA Clearing the Memory b rT eee ee ee ee C v Initializing Latitude Longitude Function 1 eR ore sue re eise READING SPEED AND COURSE S C Mode TET T Es Manual Entry of Magnetic Variation Function 4
42. JIVE 3dV2 A JOu1iNO2Q0 A13XO901NVN X DONILLINSNVULO nO8lgv2 W auN391 APO PSION SWHPZ 96 Aomna2ov XH WN pue ENS 1 e0449402 jo 111 eauxoaddy 3113gnvg v23N3S 3NOT1TVW VNYO SWMUPZ 96 Aaneey X14 WN X UNE 0bt20407 jo 06 0563 149 seen givens cao 1SVOO 1SV3 NVIOVNVO sasn POOLS zx Sesn O00 EZ 2957 9 9Z 1 2esn 000 9 AY130 1 XVW AY130 JWL NIW 2esn g r OS IS 2Sesr 000 Sssn ZIZ vc esr 000 SZ 5esn zZ 01 1 S esr 000 AW130 JWL XvVW AV130 NIW Q31VWOJ v DNLLLINSNVEL ON3031 0268 9 NIVHO S33NVT 4339 J NVHOT APA 6 N3AVW Z YOLINOW UNGNYS A ICYULNOD og x ONILLINSNWHL 174 M 3013 W GN3931 NOS 09 294 gei 016 149 esn 4 5 oo so NIVHO V3S NVIDJMHON esn gz ic E oesn 000 97 M 2esn 2 960 6 2esn 000 x AV130 3Wi AvV130 NIN J9 NVHOT ora x HOLINOW OOSSIDNV M 10WiNOD WnONYS ONILLIWSNYuUL QN3011 SP9 BSION ISINHPT 9698 Aosnocv 114 WN X UNS 010 0 muu proxddy MOS M O 0866 NIVH2 323 IGNV1331 NV3HOT Sesn 000 OS S sn 00 11 FM AW130 3Wil XVW AVI3Q0 1 NIW Dest 80 688 6 Dest 90 1 61 7 liliHvViS3 2 IHSYS39 A tazivivOoL1nv LOLINOM
43. No OM E4300 0B LP WRUWNIO OWNER S MANUAL LORAN C NAVIGATOR wor LC 9O0 H FURUNO ELECTRIC LTD NISHINOMIYA JAPAN 8509280 859 PRINTED Wt JAPAN D FURUNO ELECTRIC LTD YOUR LOCAL AGENT DEALER 9 52 ASHIHARA CHO NISHINOMIYA CITY JAPAN TELEPHONE 0798 65 2111 CABLE FURUNO NISHINOMIY A TELEX 5644 325 326 FURUNO J TELEFAX 0798 65 4200 G I GII INTRODUCTION Congratulations on your choice of the Furuno LC 90 Loran C navigator We are confident that you will enjoy many years of operation with this fine piece of equipment For over 30 years Furuno Electric Company has enjoyed an enviable reputation for quality and reliability throughout the world This dedication to excellence is furthered by our extensive global network of agents and dealers The LC 90 Loran C receiver is just one of many Furuno developments in the field of navigation Its compact size and ease of installation and operation make it suitable for use on a wide variety of vessels As with most modern instruments time and experience are required to reap maximum benefit from your new receiver To help you meet this end as quickly as possible this manual is laid out in as user friendly a manner as possible The first section covers Basic level operations and later sections cover Intermediate and Advanced operations This unit is designed and constructed to ensure the user of many years of trouble fre
44. RI and slave station values that you have used for a previously specified page the LC 90 will flash the GRI and slave offset values to warn you that in effect a contradictory command has been given to it TD Corrections Function 2 Normally you will be using the LC 90 with automatic ASF corrections so that the L L readout will be as accurate as possible You may however enter your own TD correction factors if you want to do so or if your particular geographic area doesn t have ASF compensation values available for it The procedure to enter TD correction factors would be very similar to that above for L L corrections except that you wouldn t enter Latitude or Longitude corrections on line one and two after specifying a page number but would proceed to lines four and five directly to specify GRI S1 S2 and their associated TD correction values USING ASF WHEN ENTERING TD S FOR WAYPOINTS You wil remember that cautions were given in section INTERMEDIATE LEVEL OPERATIONS concerning the necessity to Disable the automatic ASF compensation facility when you are trying to navigate to a waypoint defined by means of TD s It was explained that if you tried to use the ASF capability on such a waypoint that you would in effect be counting the ASF twice resulting in inaccurate L L readings that would lead in turn to inaccurate bearings to steer whenever a R B function is used You should also remember that we suggest that in general you should
45. Variation built in e Cross Track Error Direction to steer to get back to courseline Course Offset and Range to destination on one display screen e Entry of waypoint by Latitude Longitude TD s by Range Bearinp from present position or at Present Position e Route Planning and automatie Route following e Alarm limit setting for Cross Track Error alarm Border alarm Arrival alarm and Anchor Watch alarm e Display of signal parameters SNR visual and audible indications ECD tracking point and interference frequeney and level with six automatic notch filters built in e Display of operational parameters GRI slave selection ASF or manual correction factors auxiliary data output s and Event memory contents LC 90 SPECIFICATIONS Receiving Frequency Receiver Sensitivity Dynamic Range Differential Dynamic Range Interference Rejection Tracking Tracking Speed Settling Time Display Resolution Alarm Indications Computational Base Output Signals to Ext Equipment Ambient Temperature Range Power Supply Weight 100 KHz 1 microVolt m 110 dB 80 dB Six automatic notch filters built in These may be manually operated if desired Master plus 5 secondaries max 80 kts 5 min nominal depends on Loran signal conditions TD 0 1 microseconds L L 0 01 minutes Range 0 01 Audible and visible including Cross Track Error Arrival Border and Anchor Watch ala
46. Y SECTION The word LORAN is an acronym meaning LOng RAnge Navigation The basic principles of Loran were developed during World War II and the system implemented during that time was known as the Loran A system The superior Loran C system was developed later during the 1960 s and was put into widespread service during the late 1970 s Loran C is one of several important radionavigation systems in use by mariners throughout the world today Loran C may be thought of as a medium range system since it usually covers out to a maximum of 1200 miles from the transmitting station For very close in precision work portable microwave positioning systems are often employed by such users as the offshore oil industry and for short range medium accuracy work Decca navigation systems are used in some parts of the world For transoceanic voyages Satellite Navigation and or Omega receivers are used to provide the sort of coarse accuracy that is suitable on the open sea In other words it is rarely necessary to know your position down to the nearest meter when on an ocean voyage provided that you are reasonably certain that you are within the shipping lane and not in any danger of running aground on some nearby atoll The Loran C system was designed and established to provide excellent accuracy in the region known as the Coastal Confluence Zone or CCZ as it is often called This region extends from the shoreline seaward to the 100 fathom curve
47. ation Waypoint from Present Position Mode First let us select a single waypoint towards which you want to navigate from the present position This is normally used when you want to do a simple Range Bearing computation from your present position to the desired waypoint location Waypoint zero zero 00 has been described as a unique waypoint 00 always refers to the present position of the LC 90 In fact if you call up 00 in the WPT Mode you will find that you cannot enter data into it In order to specify a waypoint to navigate towards from your present position you need to specify the waypoint selection as From 00 to the To waypoint of interest As complicated as this is to explain in words it is really a simple process Let us say that you want to proceed to waypoint number 04 from your present location Suppose further that waypoint number 04 has already had a position stored in it let s say the position of a buoy outside the harbor Make sure first that you are in the NAV Mode and then key in the following CLR From waypoint 00 To waypoint 04 yp You should see an arrow in the third line separating the From 00 and the To 04 waypoints In other words the two digits on the left hand side represent the starting waypoint and the right hand digits represent the destination waypoint 38 If you would like to confirm the coordinates of each waypoint call up the WPT Mode and enter the waypoint number desir
48. avigation Mode The desired Route and or Waypoint s desired are selected in this Mode Cross Track Error with Course offset and Range and Bearing to the desired waypoint are also displayed PLN This is the Route Planning Mode The waypoints involved in up to ten different Route Plans are selected in this mode WPT This Mode is used to enter position data into a Waypoint Waypoint data may be entered or recalled for confirmation either as L L or as TD s CLC This is the Calculation Mode Trial rho rho calculations of Range and Bearing from waypoint to waypoint may be done here It is also possible to Define a waypoint by Range and Bearing from present position in this Mode ALM This is the Mode where Alarm limits are defined for the Cross Track Error alarm the Border alarm the Arrival alarm and the Anchor Watch alarm Secondary Function In each of these function the blue key is pressed followed by single number To leave a secondary Function hit either the left or right arrow keys 0 This is the Event Memory Function where the operator can display the contents of each event memory 1 This is the Initialization Funetion The user enters the approximate present position and if he chooses to Disable automatic selection the GRI and the slave secondaries for use by the LC 90 32 This is the Position Offset Function The operator may enter the amount of delta L L or delta TD offsets desired for a particular area
49. ce to the waypoint The LC 90 provides two forms of Range Bearing calculations to aid you in navigating to a waypoint or in navigating from waypoint to waypoint a Simple Range Bearing from Present Position to a waypoint R B Mode b Range Bearing from waypoint to waypoint CLC Mode Simple Range and Bearing from Present Position to a Waypoint R B Mode The range and the bearing from present position is the most basic information you can use to navigate to a waypoint You have learned how to select a destination waypoint in the NAV mode in the section above Now select the R B Mode by moving the Mode indicator with the left or right arrow keys until is it lined up directly over the R B Mode label The range and bearing from your present position to the waypoint selected in the NAV Mode calculated on the basis of a Great Circle course will be displayed on the bottom two lines in the R B display The range is in nautical miles and the bearing is normally Magnetic If the indication MAGV doesn t appear at the top right of the display this indicates that you have manually set 00 as a variation and that the bearing is thus relative to True North Fig 21 shows a typical display 39 we 2 313 i222 ICCC 1 L I Yv wm L LO Lo C3 Wo L Lg fn ac C3 z Fig 21 Mode Screen Range and Bearing Between Two Waypoints CLC Mode In the process of planning a voyage a series of
50. ction the VTD TTG functions don t require both a starting and destination waypoint location only a destination Waypoint To waypoint is needed However in the case of a powerboat especially the XTE AC and the VTD TTG functions are usually used together The operator uses the XTE function for instantaneous information to monitor the short term deviation from his intended track and the VTD and TTG for a long term evaluation of the progress towards his destination Thus it is a good idea to define both a Waypoint and a Waypoint To for VTD TTG functions as well as for the XTE AC functions using the NAV Mode The VTD is displayed in units of nautieal miles per hour knots and the TTG is displayed in hours and minutes up to maximum of 99 hours 59 minutes Presuming that you have set up a From waypoint of 55 and a To waypoint of 56 the display sereen below might be typical of what you would see when you call up the VTD Mode Fig 26 VTD Mode Sereen ALARM FUNCTIONS ALM Mode There are four conditions that can trigger the audible and visual alarms in the LC 90 an Off course alarm which warns you that the Cross Track Error has exceeded a preset value a Border Alarm which warns that you are approaching too close to the border of an unauthorized zone such as the border of another country an Arrival alarm to signal that you have arrived near a destination waypoint and an Anchor Watch alarm which warns that the boat
51. culations 52 ADVANCED LEVEL OPERATIONS WARNING INDICATORS The warning indications on the LC 90 serve important functions advising you when extra caution should be exercised because of a possible problem with the Loran signals Don t use position data from the display until all signal warning indicators have been extinguished These include MCYC MSNR for Master CYC SNR BLK for both slaves and PF The figure below shows secondary Function 6 displaying various receiviug status indications Fig 36 Function 6 Screen SNR Indicator Function 6 If the SNR warning indicator for any of the stations appears the signal may have become too weak to use In fact the receiver may have lost track completely or the station may have gone off the air SNR means Signal to Noise Ratio and is a relative measure of the quality of the signal in the presence of noise either generated locally on the boat or generated in the ionosphere The SNR function is also used by a servicing technician to evaluate problems either in the set itself or problems with noise generated on the boat To call up the SNR function type 6 The SNR for each station will be displayed on the lower three lines as shown in Fig 36 The table below lists the numerical values for SNR and shows what the various values mean SNR Value Table SNR DESCRIPTION SNR moe eee signal lost OF F 15 to 99 Auto aquisition tracking OK 53
52. d ALM to see your present position Compare this indicated position to that on your chart and you should see that it compares more closely than it did before ASF compensation was applied DIMMER The backlighting illumination level for the display and the keyboard may be varied in four different levels of intensity bright medium dim and off Press the DIM key four times to change the level in this sequence SUMMARY OF BASIC OPERATIONS If you have faithfully read this far you will find that you have mastered the basics necessary to use your LC 90 You now know the following e You know how to enter your approximate location in Latitude Longitude for initialization of the unit e You know that if you stay in the same general area after the unit has once been initialized that all you have to do at the start of a new day is turn the power on to the LC 90 e You know how to read your position in both L L and TD s e You know how to reduce jittery speed or L L readings with the Averaging funetion You know how to apply automatic ASF compensation for more accurate L L computations e You know how to adjust the level of illumination of the readout and the keyboard In fact you know quite a bit about the LC 90 and how to use it The next section will go deeper into more of the quite incredible things that the LC 90 can do for you 31 In this section we will start dealing with functions that will allow you to plan an
53. d of SNR values will be helpful to him If you are quite fortunate you will find that no other piece of elecironies on board your boat interferes badly with your new Loran C Assuming that your luck is with you and that this is indeed the case let s go on to test a device that in at least 90 percent of Loran C installations does cause an interference problem the alternator There are several technical reasons why alternators seem to be antagonistic toward Loran C receivers but going into the why s and wherefore s isn t as important as figuring out how to cure the little beast of this nasty habit Start your engine and increase engine speed until your charging ammeter gocs upscalc You will probably now notice that the SNR indication of your Loran C begins to plummet Not all alternators respond to interference removal techniques in the same manner Some alternators it is sad to say cannot be suppressed at all and these must be replaced or rebuilt if you wish to have useable Loran C operation Don t blame the Loran C receiver It is a sensitive instrument and it is simply responding to the noise broadcast by the alternator The first step to take when alternator noise is discovered is to try a large electrolytic capacitor mounted right at the output terminals of the alternator The capacitor must be rated for the nominal output voltage of the alternator plus a 50 safety factor For example if the alternator is a nominal 32 V D C unit yo
54. d then actually make voyages to destinations of your choice You may wish to go to a specific position such as a particular buoy or you may wish to return to a place where the fishing was good previously If you are a commercial fisherman you may want to go back to an area where you know where the hangs net hang ups are so that you may be able to avoid them and not tear up your nets ENTRY OF A POSITION INTO A WAYPOINT Mode In Navigation terminology a particular location is known as a Waypoint whether it be a starting point a destination point or an intermediate point on a voyage The LC 90 is capable of waypoint entry by four different methods a By Latitude and Longitude coordinates of a location b By TD s Time Differences of a location By using the button to store present position in a waypoint d By Range and Bearing from your present position In the early days of Loran C technology many people became quite accustomed to the use of TD s after all TD only receivers were the only ones available at reasonable prices Many commercial fishermen especially developed an extensive list of TD s where they had experienced either good fishing or had encountered hangs Modern receivers with their ability to use Latitude Longitude directly are easier to use for most people since all navigation charts are printed with Latitude and Longitude coordinates and only a relatively few charts are available with Loran
55. d to a stronger part of the pulse Also under eonditions of extremely severe signal distortion it might be necessary to aid the LC 90 in selecting the correct 10 microseconds tracking point Manual cycle stepping may expose you to skywave contamination with consequent navigational inaecuracy However you would only use this funetion in extreme fringe areas anyway where some Loran coverage is better than none at all When employing the manual cycle selection remember these points e Increasing a secondary transmitter by 10 microseconds will cause that TD to read 10 microseconds higher 56 e Increasing the master by 10 microseconds will cause both of the slave TD s to read 10 microseconds lower e Increasing all transmitters by 10 microseconds wil leave the TD s unchanged The tracking point is stepped manually by the following procedure 1 Enter Function 85 by pressing and 5 Do not press at this time The display will look like Fig 40 The TD s being received are displayed in the upper two lines 120880 299984 IO DNE mnn Hie e Cod S Fig 40 Function 5 Sereen 2 Enter 10 microsecond value or multiples of 1 microseconds for the correction on the lower three lines the third line is used for the master the fourth line is for 51 and the bottom line is for 52 After pressing the key each line will show 0 0 Then type the correction value followed by ENT For example if you
56. der when selecting slaves manually are 1 TD Gradients 2 Angle of Crossing 3 Baseline Extension and 4 Signal Strength The operator should choose the best combination of TD s taking into account all of these factors to obtain the best accuracy when operating the LC 90 manually The values for GRI and the slave station selection chosen automatically by the LC 90 are derived from considerations of Station geometry and signal strength for each geographic area We are going to have to look again briefly at some basic Loran C theory to give you some insight into how these considerations were derived TD Gradients Take a look again at Fig l on Page 5 where a section of chart was given showing an area off Yokohama Japan We determined that for the island of Mikura Jima there were three LOP s TD s that all crossed at its Southwestern corner the 9970 X 36800 9970 Y 60600 and 9970 W 17750 microsecond lines The spacing between adjacent TD s for the 9970 X TD s is 200 microseconds The spacing between adjacent TD s for the 9970 Y TD s is also 200 microseconds The spacing between adjacent TD s for the 9970 W TD s however is only 100 microseconds What this means is that for any given change in position the X and TD s change more than does the W TD This phenomenon is known as gradient and denotes the amount of echange of position for a given change of Time Difference Conversely for any change in TD s for the X and Y TD s there wo
57. e limits s we TO Pd w S X X 21 nt 2d P 4 i lt V Pd lt Fig 28 Off Course Alarm For example the touchpad sequence to use to enter a lane limit of one half nautical mile is 1 Select the fourth line by pressing W 2 Press 3 Confirm that OUT is displayed next to the message XTE If not press to change the display to Out 4 0 5 8 ENT Border Alarm ALM Mode The Border Alarm is used when you wish to define between two waypoints a line that you don t wish to cross The alarm will sound when the boat comes into the hatehed area as shown in the figure below For example assume that you want to draw a line between Waypoints 7 and 8 and that we want to be sure you don t come closer than 1 5 to that border you are in the ALM Mode the touchpad sequence would bo 1 Select the fourth line by pressing W 44 2 Press 3 Press if OUT is displayed the fourth line to change it to In 4 Press 0 O 5 ENT Fig 29 Border Line Alarm Arrival Alarm ALM Mode The Arrival Alarm is used to warn that the boat is approaching a destination waypoint The area that defines an Arrival zone is that of a circle which you approach from outside the circle The alarm will sound if the boat enters into the circle Note carefully that how tight the Arrival Alarm is set defines how close the boat must come to a desi
58. e indicator is located at the left hand edge of the panel will shift the indicator to the far right hand Mode Similarly when the indicator is at the far right end the arrow will shift the indicator to the far right hand Mode The key labeled is used to select one of the ten secondary Functions is first pressed followed by a number from 0 to 9 to these secondary Functions Note that it isn t necessary to press the key to activate the Function The LCD display will changed in accordance with the secondary Function selected by the operator The TD L LJ key is used to change position data from Latitude Longitude format to TD format and vice versa OTHER KEYS At the top left of the keyboard there are four brown keys the A and V keys stands for Event and is used when a position is to be stored in the Event Memory or Waypoint Memory or when an external plotter or printer is connected to the LC 90 The position at the moment this Key is pressed is sent out to the external instrument The brown key stands for Clear It is used to clear a number froin the display or to silence the audible alarm The two arrow shaped keys A and W used to select where the data entry cursor will be located on one of the five lines on the display The cursor will be indicated by the flashing of the far left character on the desired line Before typing in the new data the operator presses the key to clear the line
59. e unless you use an autopilot where you can add the course offset angle and in effect crab your way to the destination Look at the drawing in Fig 23 The perpendicular line from the intended track to the actual position of the boat at some time after the voyage has begun is the Cross Track Error The angle made by the actual track if it were continued on without any compensation to the destination is the Course Offset In the example it is necessary to steer to the left with a new heading equal to the original heading minus 30 degrees to compensate for the effect of wind and current N 2 OFFSET TO REACH ORIGINAL TRACK AC j Es 4 INITIAL HEADING 4 CROSS TRACK ERROR WP FROM Fig 23 In order to use the Cross Track Error function you must first select a starting waypoint Waypoint From and a destination waypoint Waypoint To using the NAV mode Note if you want to use your present position as the starting point from which you define a new track towards a destination waypoint this may be done easily also Get into the NAV Mode and enter your Starting waypoint and destination waypoint f you want to define your present position as the starting waypoint simply specify 00 as the From starting waypoint For example if you are in the process of making a voyage From waypoint 55 to waypoint 56 and you are thrown so far off course by wind or current that it is in
60. e operation However to obtain optimum performance from this equipment we ask that you read and follow the recommended procedures for installation operation and maintenance No machine can perform to the utmost of its ability unless it is installed and maintained properly We would appreciate feedback from you the end user about whether we are achieving our purposes in this manual Thank you for considering and purchasing Furuno equipment CAUTION Although your Loran C receiver is capable of providing very accurate position data no single navigational device should ever be solely relied upon Position information obtained from Loran C should always be double checked against other sources such as radar visual and celestical sightings sounding measurements etc to verify the reliability of the data FEATURES 99 4 9099 099 98959 0 5 0 c n 5 0 v9 6 9 0 0 0 0 0 b 0 0 0 0 0 e 0 9029206 SPECIFICATIONS 599 6 amp 0 0 0 o 0 b 0 0 0 0 09050 0 0 0 eee 5 ELEMENTARY THEORY Basic Navigation 0 9999 SE e Q 0 e 9 Q How Loran C WOPKS s9 28 2e e ia URS AE RET RARE NEAR OPERATIONAL OVERVIEW POWER ON OFF and DIMMER 99 5928299069850 98909 0 929980098 0 QQ NUMERIC KEYS a e q e ZE 9 9 9 w 9 9 w b D O O 0 9 9 9
61. e radius of the Arrival Alarm limit the LC 90 will signal your arrival by sounding the WCH buzzer for ten seconds Then it will automatically switch to the next waypoint in sequence For example if the next destination waypoint is 35 then the display would show 34 35 48 As described before the LC 90 will automatically display the next waypoint after passing the waypoint in use Get into the VTD R B or XTE Modes so that you can see your navigation information to the destination waypoint In many common situations you may never actually arrive at a destination waypoint and thus you may not see the unit automatically switeh to the next destination waypoint For instance if you have specified an Arrival Alarm radius of 0 19 n m and your destination waypoint 35 is a buoy in a busy harbor you may find when you get close to that buoy that a tanker has anchored nearby blocking you from ever reaching your destination Obviously you are going to have to dodge the obstacle and in so doing you would find that your Range to the desired waypoint would be increasing rather than decreasing as you swerve around the tanker In this case you will manually have to override the automatic waypoint sequencing You might also try another way to arrive at your destination waypoint This involves changing the Arrival Alarm limit to a larger number This way too is fraught with danger for if you specify the Arrival limit too loosely let s say 0 50
62. e two optimum secondaries happened to be exhibiting SNR s of 99 then we might select the 11 station to observe in order to evaluate subtle changes in SNR readings due to interference from other sources on the boat Make sure you are in Function 1 Move down to the third line using the down arrow W cursor Hit and tnen hit the key followed by to change the A to d disabling the Automatic Selection process Move the cursor with the W down arrow down to the fourth line hit 1 ENT go back to function 6 by hitting the key and then the 6 key Observe the SNR of the weakest station and write the numbers for all three stations down in the back of this manual Now you can proceed to step 4 below 4 Now turn on the other electronics on the boat radar echosounder ete one at a time and observe the SNR readings over a period of several minutes Make sure you operate the other equipment in all possible modes For example make sure that the radar is used in both standby and then transmit modes with the scanner turning and turned off ete Write down the resulting SNR s for each piece of gear and then shut it off and do the next piece of equipment If the SNR reading drops from say 90 to 85 then you are probably OK but if it drops from 90 to 60 or lower you have a definite interference problem that a qualified electronics technician is going to have to fix before you can obtain proper Loran C performance Your written recor
63. ed If the waypoint has been specified by TD s you may hit the key to see the TD s Make sure that you hit the TD lt L L key again to get back into the L L format Specification of a Pair of Waypoints From To Waypoints NAV Mode Now let s try selecting a pair of waypoints This is done whenever you want to use Cross Track Error or go between two waypoints This is also needed when you wish to specify a line defining the Border of a particular zone which you want to avoid Both Cross Track Error XTE and Border alarms will be described in detail later on in this section Let s say that you want to set up a voyage between waypoints 55 and 56 You would make sure that you are in the NAV mode by moving the left or right arrow keys to line up the Mode indicator directly over the NAV label on the front panel under the display usual the cursor will have automatically placed itself at the first point at which data may be entered on the third line You would key in 6 From waypoint 55 To waypoint 56 The display will show the starting waypoint 55 on the left hand side with an arrow pointing to the right towards the destination waypoint 56 You can now go to another function which uses waypoints since you have specified the waypoints of interest RANGE AND BEARING CALCULATIONS R B and CLC Modes To steer to a waypoint you would like to have two pieces of information the direction in which to steer and the distan
64. ed every three years with an exact replacement Please ask your dealer YOLVDIAVN O NVUOT 06 071 817 008 000 057 585 700 69 805 000 90 116 000 859 806 000 251 701 000 91 01 000 09 116 000 622 601 000 0197 6856 700 065 685 700 02X8N 24 98 10Z 810 0 dOI ST VENOUS SOI 9I VCNOMS OTAUS Wd 70 Scb 1 W qouy 1edusH 81014 ctc Iv TIV 4J0j09uuo 101224409 LNY Iaploy SNA 20329409 TITY O SETHSFO 1e2zng 901v LEObdAPC 088 685 700 095 685 906 024 801 000 694 501 000 0 1519570 dud SOIV vOIV pugog fay Agydsiq 0IV coly I01V ON 3002 i TOANAS 69 YUOLVDIAVN O NVUOT 06 071 2 5 2 Ha 7208120 Waag 3 7 2 279 100 FEQXL PLZ bd Ang gx 7 gs b Qd 740 x4 n 5557 x0 4 70 SISSA T nap L Y 0 0 L L L
65. ed in the upper two lines During the ealeulation the degree indications will be flashing Wait until the L L readout and the flashing degree indications stabilize before proceeding to another Mode or Function SELECTING WAYPOINT S FOR USE WITH OTHER MODES AND FUNCTIONS NAV Mode To prepare for making navigation calculations using waypoint s you must first select either the single waypoint towards which you want to proceed from your present position or you must specify the two waypoints between which you want to travel The NAV Mode is used to select waypoint s for later use in other Modes 37 To specify the waypoint s of interest call up the NAV mode by pressing or P to line up the Mode indicator directly over the NAV label on the panel under the display The display should now look similar to the figure below where the cursor will be flashing on the third line Fig 20 NAV Mode Screen There are three ways in which Waypoint information may be selected in the NAV mode As a destination waypoint from your present position 00 b As a pair of waypoints the left hand one being the From waypoint and the right hand one being the To waypoint pair of waypoints in a Route which is a preplanned set of waypoints which you want to follow in sequence This latter type of waypoint selection in the NAV Mode will be covered later on in this section when Route Planning is discussed Selection of a Destin
66. efficient merely to return back to the original track to continue on to waypoint 56 then you may use the NAV Mode to specify a new track by keying in 0056 which translates to From present position To way point 26 You will now see the Cross Track Error and Course Offset AC 41 displayed on the upper two lines of the NAV Mode You would however be better off going back to the XTE Mode rather than staying in the NAV Mode since your present position isn t shown in the NAV Mode Get back in the XTE mode by pressing lt or p Fig 24 shows a typical XTE display Your present position is displayed on the upper two lines The waypoint numbers selected are displayed next to the label WPT on the third line The XTE on the fourth line varies from 0 01 to 9 99 nautical miles The bar indicates to which side of the desired track the vessel is off track and the arrow points in the direction in which you must steer to get back on course If the XTE is within the preset alarm zone single arrow and bar will appear If the XTE exceeds the preset value two arrows and bars will be displayed We will get into the setting of the various alarm zones later on in this section The numbers on the bottom line deseribe the Course Offset AC and the Distance to the waypoint The minus sign in front of the offset indicates that it is necessary to steer to the left The offset angle is indicated up a maximum of 99 degrees When you have passed the To wayp
67. en t available you may want to enter manual L L corrections In other cases you may want to further refine the absolute accuracy of L L coordinates to match a particular chart where the chart has been drawn using a different datum reference than the WGS 72 datum used by the LC 90 In either of these cases you must first determine the amount by which you need to shift the L L readings This is done by comparing the displayed L L with the actual L L that you want the unit to read or by using the correction data printed on the chart itself n the first ease where you you are presently located at a position whose L L coordinates are accurately known you may compute the difference in L L between what the LC 90 is showing and what you know to be the actual coordinates Then you would enter the differential values as manual L L corrections The second ease is where you want to mateh up your L L coordinates with that of a chart printed using a different datum reference The LC 30 calculates Latitude Longitude coordinates according to the WGS 72 World Geodetic System 1972 datum model Many older eharts are drawn using other datum models for example Clarke 1866 1880 or Bessel 1841 The position ealeulated by the LC 90 may not be the same as the expected position on these older types of charts For example reprinted below is a comment found on an older U S DMA chart On this chart it is necessary to add corrections of 11 49 seconds South
68. enerating the TD s you want to enter Another important point if the automatic ASF compensation funetion is activated as recommended for most operations and if you wish to convert 39 from TD s to L L the ASF function must be disabled you don t do this you will be in effect counting the ASF twice and any Range Bearing readings to the resulting waypoint will be inaccurate In the section on Advanced Level Operations we will describe the operations to use in order to employ more fully the benefits of the automatic ASF compensation capabilities of the LC 90 even when using TD s to enter a position You can disable the automatic ASF compensation function using Function 4 The sequence of operations is 1 Call up Function 4 and disable the ASF Auto function if it is on The keystroke sequence is as follows L 14 LENT Fig 19 Function 4 Screen 2 Call up the WPT Function by moving the left or right arrow key until the Mode indicator arrow is lined up directly over the WPT label on the panel under the display Specify the waypoint number into which you wish to store the TD information we ll use waypoint zero eight here and then enter the desired information The following touchpad sequence would be used CLR 0 8 ENTJ FD L LJUU 2 8 8 5 9 ENT CLR 2 7 9 3 2 3 ENT 3 Now switch back to the L L display to see the resulting L L You must wait for the L L display to
69. ete self check TD of unselected slave having larger coding dolay appears Large amount of error in both 51 and 52 TD s board is turned off 2 Power plug is loose or out 2 Secure it firmly 3 MAINT fuse 2A at rear 5 Check mains voltage and pane has blown polarity first and puf new fuse If blown again call for service When driven from AC mains check rectitier unit Too 4 Faulty circuit 4 Call for service 1 Faulty circuit 1 Call for service If any number if displayed on one of the readouts note and tell service technician 1 Selected slave is of f the 1 Call up coast station or ask air neighboring boats for signal conditions Long delayed skywave of master Signal has been acquired 1 Turn off and repeat whole acquisition sequence 67 SYMPTOM POSSIBLE CAUSE REMEDY Large amount of error 1 Long delayed skywave of the 1 Repeat the slave signal only in S1 or 52 TD slave signal has been acquisition acquired The slave is of f the air 2 Call up coast station or ask neighboring boats for signal conditions The slave station 1 too close 30 nem or less too far 750 or more 1005 step error in 51 or S2 TD 10 20 or 5005 1 Correct it manually Over land signal is received 2 Correct it manually The master station is too close 50 n m or less or too far 750 n m or
70. fected To change the Averaging constant access Function 3 The amount presently used will be shown on the first line to the right of the label AvE To enter an averaging constant of 4 you would use the following keystroke sequence 4 Entering Averaging constant of 4 For the time being don t worry about the other lines on the display We ll get into those subjects later AUTOMATIC ASF Function 4 You will remember that in the Elementary Theory Section that we said that the LC 90 has a built in capability of using TD offsets to compensate for warpage of the TD grid occurring due to ASF Additional Secondary Factors caused by propagation of the Loran signals over part land part sea paths This automatic ASF compensation will yield better accuracy of the calculated Latitude Longitude than will the raw calculation using uncompensated T numbers When the LC 90 is first used after the memory has been cleared the default setting for automatic ASF compensation is off For most operations using latitude longitude it is desirable to have the automatic compensation engaged all the time Only when TD numbers perhaps from a fishing buddy or your own old records from another Loran C receiver are used will it be necessary to disable automatic ASF compensation The LC 90 contains built in table of ASF compensation values for geographic areas where these warpages have been measured by the U S and Canadian Coast Guards but other areas
71. h all Loran C transmitters work on the same frequeney 100 KHz they ean all be sorted out by GRI You wil remember that the Time Difference s LTD S are measured in microseconds millionths of a second Further the designers of the Loran C system have assigned an identifying letter code to each slave station in a chain These are oalled either X Y W or Z Now look back at the section of chart in Fig 1 that shows part of the area near the coast of Japan You can now better appreciate why the TD s are labeled as they are The GRI in the label comes first then the identifying eode letter and then the time difference in microseconds Your Loran C receiver is considerably more sophisticated than the simple TD only receivers we have been describing here It is capable of computing Latitude and Longitude directly from these TD s This is a complex calculation and again the fundamental assumption made is that the velocity of propagation of the signal is constant While this is true for propagation over seawater the velocity is altered slightly when the signals travel over land Over land the velocity is affected by such factors as the conductivity of the soil and the features of the terrain These effects are all lumped together under the title of Additional Secondary Factors or ASF These factors cannot be modeled exactly in the TD to Latitude Longitude mathematical conversion The LC 90 however has TD offsets built into it describi
72. h clearance both to get to the connectors behind the unit and to allow you to get your hands in on both sides to loosen or tighten the mounting knobs Make sure you leave at least a foot or so of service loop of cables behind the unit so that it can be pulled forward for servicing or easy removal of the connectors S S NOmm 4 4 MOUNTING HOLES 4 96 y WS p d x Weight 2 5 If you find it necessary to remove the antenna connector that goes to the display follow the directions in the drawing below If you don t know how to solder or if you don t know how to do it well it s best you leave this part to a compctent service technician In perhaps 50 percent of installation problems poor soldering or wrong wiring of the connectors is where the problem lies DO NOT SHORT ANTENNA CABLE Coupling Ring Solder Hole Plug Assembly gt Cut end of cable even Bare 17 0 67 of center Screw the plug assembly on Remove vinyl jacket 34mm conductor don t nick conduc cable Solder plug assembly 1 54 don t nick braid tor Trim braided shield 15mm to braid through solder 0 6 and tin Slide holes Solder conductor to coupling ring on cable contact sleeve Fig 10 Unless you are also installing optional peripheral equipment such Track Plotter autopilot or a Printer the only wiring necessary is for the power connection and the antenna cable 19 Connection
73. he master and the two secondaries is also displayed as well as the numerical SNR value for each station 8 This is the Tuning Indicator Function The operator may display the level of signals both interfering and desired from 70 to 130 KHz 9 This is the Notch Filter status Function where the frequency of each automatie noteh filter may be displayed and if desired where each of the six filters may be set manually on desired frequencies The level of signal on the frequency of each filter is displayed as well 13 enjeA 1959 44 AQYDUY RAI 42V en eA eseJgd Jepaog esano2 j40 514245 UO 41505 4005904 dM 5 dM 45215 ON ej nou Dura eeg WN sa BE uo 4eu 49580 G CN 41504 4005914 SgM 2 AOE 6 L 41504 4495944 N res UJ LI ASW 3u811 03 339 06 91 y Jo e dsrp y Joued y uo Avy ayy peoe d sueeJos 9UuJ su aos IA SdM CM uee joq O L WO 4 54 B od 1504 LUeSe 4g A OVW 3SY 2 8 oDuey SoM ON 84noy ov 1320204293 35241 55049 911 09 eut GLA 42014590 201 1 WOY 3 5 41504 SdM O uee 1eq DurJeeg 4 GEID Cec 3 i sius q e mO zm t d O C L 1 li
74. her words TD s are observed phenomena and Latitude Longitude numbers are derived mathematieally from this observed data READING SPEED AND COURSE S C Mode Verify that the Mode indicator arrow is lined up over the S C label It will take a minute or two after the receiver has finished its acquisition process but you will eventually see the display showing the Speed Made Good and Course Made Good Of course if you are presently at the dock the speed should be close to zero and the course will randomly vary around the compass rose Note this function as well as many others will only work after the receiver has completed the acquisition process and after all warning indications have been extinguished The Speed Made Good is defined as the speed over ground and is calibrated in knots The Course Made Good is referenced to Magnetic North whenever the MAGV label is shown in the upper right hand side of the display The amount of Magnetic Variation is automatically calculated by the LC 90 for the your geographie area You may at this time wish to look at the amount of 28 magnetic variation presently being used This can be done by accessing Function 4 Press the key followed by the 4 key A typical display is shown in Fig 16 The label vAr in the top line of the refers to Magnetic Variation and the A shown refers to Auto indicating that the variation is applied automatically Fig 16 Funetion 4 Sereen The preprog
75. here is a large LCD readout taking up most of the left hand side of the front panel a keyboard on the right hand side and all sorts of abbreviations printed on the panel below the display These nine abbreviated labels indicate the various Modes in which the LC 90 may be operated In addition there are 10 secondary Functions which may be called up to do less often used operations These Functions are accessed by use of the key followed by a number from 0 to 9 The keyboard itself contains twenty three membrane sealed touchpad keys and is divided roughly into four functional areas delineated by different color schemes A distinctive beep is generated to confirm to the user that something did indeed occur whenever he presses a key The functional groupings of the touchpad keys are as follows POWER ON OFF and DIMMER These three brown keys are located at the top right of the keyboard When the operator presses the key the LC 90 is activated After several seconds the display will begin to show some activity is necessary to press both the and the keys simultaneously in order to turn off power to the unit This procedure is necessary to prevent unintentional interruption of power should the user accidentally hit the PWR key The DIM key is used to vary the level of backlighting of the display and keyboard for nighttime operation There are four levels of backlighting intensity bright medium dim and off Each time the DIM
76. his case the unit requires a starting location within about 1 degree of the actual location Similarly if you move the LC 90 more than about 60 miles approximately 1 degree in latitude with the power off you will need to reestablish the approximate starting position Before you start operation obtain Navigation Chart for your area preferably one with Loran C TD lines overprinted on it Keep this chart nearby as you go through the various procedures so that you can verify that the LC 90 is giving you reliable and sensible numbers Clearing the Memory The very first time you turn on your new unit you will have to clear the internal memory to ensure that no stray data has been stored there Make very sure that you want to clear the memory completely before you do this all information ineluding waypoints that you may want to keep will be lost after this operation Make sure the LC 90 is turned off first and then hold down the CLR touchpad while pressing the key Hold the key down until you hear two beeps and then you may release it a U JU U U UU U UU U UL UU a After the memory has been cleared or after you call up Function 1 you will find the cursor on the latitude line After clearing memory you will find 26 that the line is full of dashes After hitting the button after calling up Function 1 you will find the line full of dashes Enter your approximate latitude Assume for sake of illustration
77. installed correctly It should be mounted as high as possible on the boat free from the influences of nearby antennas rigging and masts Since it is rarely possible to avoid nearby metallic objects especially on small boats a compromise must be struck on most boats Most skippers prefer to have their VHF antenna on the highest mast because this is their primary means to signal a distress situation The second most critical picce of electronics on the boat however should be the Loran C antenna and if this must be on the same mast as the VHF antenna at least try to mount it on a crosstree on the other side of the mast from the VHF antenna A separation between antennas of at least 3 feet is needed Loran C antennas can perform adequately sailboats with transom installations but in marginal signal areas the performance may not be satisfactory The presence of stays and other metallic rigging can cause the reception pattern to be somewhat more favorable in certain directions instead of being omnidirectional like it should be Obviously it is a real nuisance to have to point the boat in a particular direction in order to find out where you are There are many sailboat installations where an insulated stay works adequately but a separate whip antenna up in the clear is still preferable Antenna siting is not all science but neither is it all black magie either To determine the best location on your own boat it is suggested that you te
78. ion 4 and then select the d mode using the key Move the cursor down to the second line and type in 00 for the variation entire sequence is 4 0 True North bearings The MAGV indicator at the top of the display will disappear 29 SETTING THE AVERAGING TIME Function 3 If you are still presently sitting at the dock while you are learning the operation of your new Loran C navigator you may note that the speed reading varies a bit in a random fashion This is a function of several factors most noteworthy being the strength of the incoming Loran C signals and the minute random variations of the propagation path between you and the transmitting station The calculation of speed is sensitive to these random variations especially at low speeds You may smooth out excessive speed fluctuations by specifying an averaging time constant that in essence lengthens the time interval over which the ecaleulation is done The tradeoff for a less jittery speed readout is that sudden changes in speed actual acceleration or deceleration of the boat take longer to show up on the S C readout In general an Averaging time constant of 1 to 4 is a practical value for most people but you may want to experiment some with the value that most suits you It should be noted that the Averaging time constant will affect the speed that the Latitude Longitude readout changes as well as the Speed readout but that the TD readout will not be af
79. keep the automatic ASF compensation engaged for more accurate L L readings There is a way around this seeming contradiction in instructions when you are entering TD values for conversion to L L coordinates and storage as waypoints involves a little more work on your part but it will give more accurate R B readings with ASF constantly engaged for all functions Basically the process involves looking at Function 4 to determine what the actual values for the ASF compensation are and then manually adding or Subtracting the same values from whatever TD s you wish to enter into the LC 90 for conversion into a waypoint in the WPT Mode An example should serve to illustrate this technique Assume that you are in the San Francisco area at L L coordinates of 37 degrees 38 minutes North latitude and 122 degrees 24 minutes West longitude Call up Function 1 Make sure you are in the Automatic mode If you aren t in the Automatic mode you should turn off the PWR call up Function 1 then call up the Automatie Selection process You will see that the optimum GRI is 9940 and that the LC 90 has automatieally selected the slave seeondaries 27 and 43 Now call up Funetion 4 The value for ASF for S1 the 27 line is 1 2 microseconds and the value for ASF for S2 the 43 line is 0 4 microseconds When the LC 90 is using the automatic ASF compensation facility it takes the TD s displayed on the front panel and adds these compensation values interna
80. l Alarm e 0 9 9 989 amp 9 6 9 9 0 9 t QR ee 9 e 99 999 9 6 x 9 0 9 9 9 9 9 9 9 9 9 b 9 9 Anchor Watch e e 0 0 6 0 9 0699992252599 0 0 9 90 09 o m l 00 e ROUTE FUNCTIONS Storing a Route PLN Mode Following a Route NAV Mode E E E EE EE e e Q amp 9 b 5 8 9 9 9 s 9 0 Temporarily Deselecting Waypoint in a Route PLN Mode EVENT MEMORY Storing Present Position into an Event Memory Storing Present Position into a Waypoint Memory WPT Mode EAE CONVERTING COORDINATES WPT Mode ADVANCED LEVEL OPERATIONS 5999 0 0 bn P 9 5 99 ere WARNING INDICATORS Er oh se See eee we TIT jare SNR Indieator Funetion 46 CYC Indicator Function 6 8 0 6 b n 9 9 0 P b b 9 ECD Function 6 OE te E Noe ee Deviation Function 6 Audible SNR Function 7 me BLINK Indicator b e 0 0 Power Failure Indicator T 9 99 9 99 ba h bo 99 9 9 o b 0 0 ee 8 9 8 0 9 5B B DB b 9 8B b 9 9 9 b p 9 9 MANUAL CONTROL OF LORAN RECEPTION Manual Cycle Selectio
81. l as shown on a navigation chart This manual compensation facility is in addition to the automatic ASF compensation function You must thus be careful that you don t inadvertently call up both functions simultaneously because then you will be in effect making a double compensation you probably didn t intend to invoke The LC 90 has ten pages into which correction information either by L L and or by TD may be entered These pages are identified by the exact GRI and slave TD s that are entered into each page and will be automatically 58 invoked by the computer whenever the vessel enters an area bounded by these numbers For example if you specify a set of correction values in page 01 using a GRI of 9940 U S West Coast chain with slaves of 42 and 26 then this page will be invoked only when the first two digits of the boat s slave TD s are equal to 42 and 26 when the GRI of 9940 is in effect This manual position offset correction facility should be specified only for areas where automatic ASF corrections are not available At present the LC 90 has correction values built in for the entire U S and Canadian coasts but since correction values are presently not available anywhere else in the world the ASF corrections outside these areas are absent L L Correction Funetion 2 Variations in signal propagation velocity can cause constant errors in the computed Lat Long position In geographic areas where automatic ASF corrections ar
82. lly before making the TD to L L conversion You will be doing the same thing manually 61 Let s say that your fishing buddy gives you set of TD s where the fishing is particularly good at 27260 0 and 43143 0 microseconds To the 27260 0 value you would add the ASF of 1 2 microseconds yielding 27261 2 microseconds To the 43143 0 value you would add 0 4 microseconds yielding 43142 6 microseconds Now enter these into your scratchpad waypoint 99 by TD s WPT Mode and convert to L L The resulting L L in Mode will be 37 degrees 39 00 minutes North latitude 122 degrees 23 94 minutes West longitude Scratchpad Waypoint 99 Now a R B calculation from present your present position to this waypoint with the ASF enabled use Function 4 will result in the correct bearing to take for you to join up with your friend This method of specifying a waypoint by manually adding the ASF compensation values will allow you to keep the ASF function constantly engaged and will result in less confusion when making any calculation involving waypoint s plus it will result in more accurate L L readouts all the time MANUAL GRI SLAVE SELECTION Function 1 So far you have been using your LC 90 on one Loran C chain and have been using the pair of slave stations selected automatically for you by the unit In many geographic areas however there may be more than one pair of slave stations available The most important factors to consi
83. may be dragging its anchor For each of these funetions the operator may preset the limits he wants to work with WCH XTE ASF MAG V 9 13900 ee 385w Fig 27 ALM Mode Sereen 43 Fig 27 shows typical ALM display The present position is displayed on the upper two lines The ON or OFF on the third line indicates whether the unit is preset to sound an audible alarm or not This status can be changed by using the key sequence of j The value for the Off Course or Border alarm is entered on the fourth line and that for the Anchor Wateh or Arrival alarm is entered on the fifth line CA limit of 0 00 means the alarm is off The alarm wil sound when the boat crosses the preset alarm zone from inside or outside The in and Out on the bottom two lines indicate which direction is preset for the alarm function In indicates that the alarm will sound if the vessel ventures into the area and Out indicates that the alarm will sound if the vessel ventures outside the desired area If an alarm is activated a visual alarm indication WCH and or XTE will also appear at the top of the display Off Course Alarm ALM Mode The Off Course alarm is used when the Cross Track Error function is being used You may preset the alarm limit from 0 00 i e the alarm is disabled to maximum lane width of 20 that is 9 99 each side of lane center The Off Course alarm will sound if you go out of the lan
84. more Same amount of 10us step error in both St and S2 TD s 1 Correct it manually Over the land master signal is received 2 Same as above 1 Signal is weak 1 Check SNR reading If available select another slave or chain SNR indicator on 2 The station is of f the air 2 Call up coast station or ask neighboring boats for signal conditions 3 Heavy interference exists 5 Read just notch filter 1 Over the land signal is received 1 Watch TD s carefully before position fixing CYC indicator on occasionally Degree labe on L L display blinks 1 Check SNR reading If available select another slave or chain Signal is weak Power went off but recovered sometime in the past Position roading may be suspect PF indicator on 1 If the display is in error turn off the unit and search signals again or use manual tracking function 5 NO TE For some Loran chains current status and schedules of the chain operation are provided on a prerecorded telephone service in the U S A 9960 8970 7980 Chains Tel 607 869 5395 Lorstas Seneca NY 904 569 5241 Malone FL Consult your dealer or service agent about how to obtain the latest Loran information REPLACEMENT OF KEEP ALIVE BATTERY The estimated life of the Keep alive battery is three years However to ensure trouble free operation it is suggested that the battery be replac
85. mporarily mount the antenna in a likely location and try it out Later in this section the recommended test method will be given to determine if the installation site is OK Mount hero or heroe BAD PLACEMENT shrouded by stays Fig 6 Typieal Antenna Placement 17 The Antenna Coupler uses a standard 96 inch fiberglass marine CB whip which is screwed into the top fitting NOTE so called loaded whips which are much shorter than 96 inches are not suitable as a whip for the LC 90 The body of the Antenna Coupler can be mounted in two ways 1 The bottom of the coupler is designed to accept a threaded extension mast recommended height no longer than about 5 feet to prevent undue flexing of the mast in heavy winds The thread should be 1 inch diameter with a piteh of 14 threads per inch 2 The side of the coupler has a molded channel so that it may be mounted directly to a stub mast with the two stainless steel hose clamps provided in the installation material See the drawing below I 2 5mm 96 inch HOSE CLAMP exe WH I TWORTH THREAD Be W25 14 mn eJ TE Fig 7 ni The Antenna Coupler Unit comes with the interconnecting cable already prewired into it from the factory You may however find it necessary to deal with the display end of the cable since the connector is supplied already wired to the display end The connector may not fit through holes and
86. n Function 5 Manual Notch Filter Setting Function 9 Pa a amp 9 b 9 S 9 9 amp 5 p bo p b 09 ph bo 59696 MANUAL POSITION OFFSET CORRECTIONS L L Corrections Function 2 Corrections Function 2 958899 b o 0 o 9 b bete b 959 9 6 aa 4 o 9 8 b n se iii 0 b o 992559 99999280 0 b 33 34 37 38 39 39 40 41 42 44 44 45 45 41 48 49 20 91 91 53 94 54 54 55 56 56 96 57 59 61 USING ASF WHEN ENTERING TD S FOR WAYPOINTS MANUAL GRI SLAVE SELECTION Function 1 TD Gradients e 0 Sr EE SE GG 0 Q 0 q 60 0 q 9 Angle of Crossing e 6 E 9 9 9 9 9 9 O 9 o9 9 0 e e HOLDING THE TRACKING POINT Function 7 204a RS RUE AMA ESTE OV SELECTING OUTPUT DATA FORMAT Function 3 TUNING INDICATION Function 8 0 99 99 9 9 TROUBLESHOOTING Self oneok d WE RU V E RN E eR ERE Wr tes qx sx ere e RR Self cheek 2 9 e b 9 9 90 09 0 6 88 9 09 0 9 G e SCHEMATICS APPENDIX A CHARTS OF VARIOUS LORAN C CHAINS SHOWING RECOMMENDED TD PAIRS 9995 9899 9 9 o 61 62 62 63 64 64 65 66 66 F
87. n also but that the exact line isn t printed on the chart explicitly it is necessary to interpolate between lines that actually are printed in order to get this TD and by so doing we would come up with a TD of approximately 17750 microseconds Now let s consider in more detail the way Loran C actually works HOW LORAN C WORKS The Loran C system is a pulsed system whose fundamental assumption is that the speed of propagation of a radio wave is constant anywhere in the area of coverage of the system This assumption is actually subject to some corrections but we wil assume for the sake of this discussion that the speed of a Loran C signal is actually constant Since distance time and speed are all related and sinee we have assumed that the speed of the signal is constant if we can devise some means to measure the time that it takes for a signal to arrive from a distant transmitter we can easily calculate the distance the signal has travelled to get to us Thank goodness for modern eleectronies for it provides means for making very precise time measurements down to the order of tenths of milionths of seconds S Ks x a Z 8 2 a e D N n sJ lt gt 5 NL 8 Y g Hu N SLAVE R ceg e 7 lt Pd rd 7 2 7 x nd P ed d T7 ef gt 4 4 7 4 d 4 ee 47 Fig 2 Simple Loran C System
88. n enclosed cabinet behind the wheel and most have clear doors so that equipment may be seen behind them FURUNO WILL ASSUME NO RESPONSIBILITY FOR CORROSION DAMAGE CAUSED BY EXPOSURE TO EITHER FRESH OR SALT WATER SPRAY The LC 90 consumes very little power so there is no need for forced air ventilation However it is necessary to provide at least some space behind and around the Display Unit to allow some circulation of cooling air and to provide convenient access to the rear connectors If the Display is mounted in the center cabinet of a center console type of boat usually there is sufficient air movement to cool the unit properly Even though the LCD Liquid Crystal readout displays are quite legible even in bright sunlight it is a good idea to keep the Display Unit out of direct sunlight or at lcast shaded because of heat that can build up inside the cabinet is a regrettable fact of modern life that small attractive electronic gear seems to attract undue attention from thieves In your installation planning it is a good idea to provide means either to hide the gear when you are not aboard or take the gear off the boat completely when you are finished for the day Consideration should be made to provide space for access to the mounting hardware on the side and to the connectors behind the Display Unit 16 DETAILED INSTALLATION INSTRUCTIONS Antenna Coupler Unit Installation The antenna coupler unit is completely watertight when
89. n m you will indeed allow the automatic switching to the next destination waypoint to occur but you may then define a new course to the next waypoint that takes you through a seawall or over land If is far better to leave a reasonable Arrival Alarm limit of say 0 19 n m and when you get as close as safely possible to the desired waypoint which 1s now blocked then manually override the Route planning Mode and go to manual waypoint sequencing If you are adamant about staying in the automatic waypoint sequencing Mode then you may take another tack you may temporarily deselect waypoints that you have already passed and then proceed automatically again Temporarily Deselecting a Waypoint in a Route PLN Mode A waypoint in a route may be deselected temporarily by entering a minus to the left of the waypoint number selected in the PLN mode The temporarily neglected waypoint may be used again at any time by changing the with the key For example let s use our tanker problem situation where the original Route Plan was Route 02 gi Wh Fe gt Let s assume that you have successfully negotiated waypoints 01 and 02 and that you are presently going from waypoint 02 to waypoint 05 You find that you are blocked from arriving at waypoint 05 by the tanker After you dodge the obstacle you now want the LC 90 to get you from your present position to waypoint 06 and then from waypoint 06 to 07 etc afterwards You mu
90. ng deviations from the ideal grid The offsets were actually measured at sea The LC 90 can automatically take these warpages into account to give more accurate computation of Latitude and Longitude than ean a receiver without this automatic ASF correction Note that the TD grids on a Loran C overlaid chart can be shifted when the chart is printed and thus compensated to take care of actual observed readings from the field One should still be careful when using Latitude Longitude numbers directly from a Loran C receiver especially when near land since this is where significant errors can occur Note that the charts don t even show Loran C grids over inland areas because of the extreme distortions in the lattices over land Also Loran C is not meant to be used in harbors or ports since these are usually surrounded by land masses Well enough theory for now Let s get down to how you actually operate your new receiver Some advanced concepts and further cautions on the use and misuse of tne system will be given later Fig 3 LC 90 Control Head Panel OPERATIONAL OVERVIEW The LC 90 is basienlly a rather simple unit to operate although at first glance it may be a little intimidating to someone who has never used a Loran C navigator before However once you get to know what the various abbreviations mean the simplicity and logic behind layout and the design will become more apparent Examine the front panel You will note that t
91. ning voyages make this distinction between From and To even though any one particular waypoint may be used for either purpose since each waypoint defines a specific location on earth whether you want to go towards it or away from it Let us assume for purposes of illustration that we wish to enter the Latitude and Longitude position of San Francisco into Waypoint Zero Seven The coordinates are 37 degrees 40 00 minutes North Latitude and 122 degrees 24 00 minutes West Longitude You would of course enter your own approximate L L coordinates The sequence of keypunch operations would be as follows 1 Move the right arrow key until the Mode indicator arrow is directly over the WPT label on the front panel beneath the display Observe the waypoint number in use there now The waypoint number is located on the third line next to the label The first digit of the waypoint number will be flashing to indicate that the data entry cursor is presently at this location The latitude and longitude of the waypoint in use at this time are displayed on lines four and five of the display If you want to see the TD s that correspond to the L L for this waypoint hit the TD lt gt L L key the key again to get back to the L L readout Note if the L L is zero degrees latitude and longitude in a waypoint the corresponding TD s will be non zero values representing the TD s that would be present at zero latitude zero longitude The exact
92. nutes South may be entered by using the following keystroke sequence 0 9 0 0 9 00 19 S Latitude Correction The eursor will automatically advance to the next line after the ENT key is hit Type the correction value for Longitude on the second line For example to enter 0 17 minutes East use the following keystroke sequence 0 0 00 17 East Correction Note that the key cause the corrections to be entered in South Latitude and West Longitude Now you must define the GRI and the slave TD s where these corrections will automatically go into effect Let us use an example of a geographic area which has not been surveyed by actual at sea measurements of TD grid warpage Japan this case we want to specify the GRI to be 9970 and the first two digits of Sl and to be 18 and 36 respectively The following keystroke sequence would be appropriate once the cursor has automatically moved down to the third line after was hit in step 4 above CLR 9 9 7 0 ENT CLR 8 ENT CLR 3 6 LENT 60 6 The above L L offset values will now be applied whenever you are in the geographic area bounded by these values in our example above when you move the vessel to where the first two digits of the slave S1 are 18 and where the first two digits of the slave S2 are 36 Whenever L L or TD corrections are automatically applied a A T L symbol will appear If by chance you try to specify a new page using the same G
93. oint a minus sign will appear to the left of the distance display Fig 24 XTE Mode Screen VELOCITY TO DESTINATION AND TIME TO GO VTD Mode Velocity To Destination VTD is differentiated from Speed Made Good in that VTD is a vector quantity while speed is a scalar quantity veetor quantity denotes not only the magnitude of speed movement but also the direction whereas a scalar quantity denotes magnitude only In this particular case then VTD defines the amount of speed in the direction of the desired destination The reason for all this seeming complication is that not only can wind and current move a vessel off its intended track but so ean intentional movements such as when a sailboat tacks into the wind In the case of a sailboat it is very beneficial for the skipper to know how mueh headway he is making toward the desired destination as he tries various taeking angles to optimize his progress towards a mark WP DESIRED COURSE VA ACTUAL ie sues COURSE de rip 25 PRESENT POSITION 42 The Time To Go TTG is the amount of time necessary to get to the desired destination if the present is maintained is obviously an estimate since in the case of a sailboat a series of tacking maneuvers is usually necessary in order to get to a location and in the case of a powerboat the effects of wind and current are usually not constant over a voyage Unlike the Cross Track Error fun
94. on the correct side of the baseline and its associated bascline extension where the baseline between the master and slave station is extended on through past the slave Without all the jargon the TD s for the position you want to put into a waypoint must be within about one hundred miles or so of your present position in order to use the TD to L L conversion and they shouldn t be on the opposite side of a baseline extension from your present position It is a good idea to plot the resulting L L reading that the LC 90 comes up with in making the conversion between TD s and L L on a chart to see if the calculated position makes sense to you Let us use the following numbers as an example The GRI in use is 9940 and the Slave stations in use are the 11 and the 27 lines We assume here that LC 90 has already locked onto the signals and that the desired TD s are relatively close by for example they may have been sent to you over the VHF radio by a fishing buddy The TD s to be converted are 12885 0 and 27932 4 microseconds The approximate Latitude Longitude at these TD s is 44 degrees 30 minutes North Latitude and 124 degrees zero minutes West Longitude Note that the slave stations that the LC 90 is presently tracking should be the same as the TD s you want to use to make the conversion between TD s and Latitude and Longitude and it is necessary for the GRI in actual use to be the same as the one that was originally used for g
95. on this small section of 6000 0 v A S gt 3 5 J 3j gt 8 amp amp N S 5 36600 Nj MIC GR1 9970 x 50 37000 a 7 Fig 1 Loran C Chart off Yokohama chart These TD lines are labeled with numbers in units of microseconds on the outer edges of the chart The spacing between adjacent TD s will vary depending on the seale of the chart as well as the section of geography being covered Don t worry about these details just yet but note that in this particular example the spacing between adjacent TD s is either 100 or 200 microseconds Just note that for any one position on the chart that is at any one particular Latitude and Longitude there is at least one pair of Loran C TD s that cross each other There may in fact be more than one pair of TD s that cross each other at our one point of interest Some of them may give you better accuracy than others Again we ll delve into that in more detail later As an example let s find a point on the chart and compare the position both by Latitude Longitude and by Loran C TD s At a Latitude of 33 degrees 52 minutes North and a Longitude of 139 degrees 35 minutes East you should find the Southeast corner of Mikura Jima Island This position corresponds to the crossing of the two TD s lines of 36800 microseconds and 60600 microseconds Note that a third TD erosses this positio
96. ond line indicating that the receiver is using Automatic notch filter operation Fig 41 Function 9 Screen 2 On the third line type a filter number after pressing CLR Do not press at this moment Let s assume that you want to use notch filter 4 Hit the 4 touchpad 3 Press until the indication d referring to Disabling the Automatic notch filter operation is displayed next to the filter number for manual tuning To disable the filter completely press until an o referring to Off is displayed 4 Now press ENT 9 Type the frequeney of the interfering signal on the fourth line For example press 0 8 for an interfering signal of 88 KHz The signal strength of the selected frequeney can be read on the bottom line 6 You would do the same procedure from 2 through 4 above if you also wanted noteh filter number 5 for example to be assigned manually to 88 KHz duty T To return to automatic tuning you would need to hit the key until an A Automatic is displayed on the third line instead of d or 8 The frequency and level of the interference signal eliminated by each noteh filter can be read on the lower two lines while the filter number is specified on tne third line MANUAL POSITION OFFSET CORRECTIONS The LC 90 is capable of storing L L correction and or TD corrections internally for compensation of the L L readout so that it more closely matches the actual position of the vesse
97. one of these messages are displayed the CPU board 04P4044 should be replaced with a new one Self Check 2 This self check 2 is provided to check the LCD display the output data to the peripheral equipment and the keyboard To perform this check press the key just after the key is pressed Hold the key down until you hear two beeps and then you may release it The display will go through the following scquenee automatically until the unit is turned off There are two sequences in accordance with the following initia setup conditions you insert a test plug made locally using an SRC connector type SRCN6A16 10P Code No 000 508 663 pins 2 4 and 6 shorted together and pins 1 and 43 shorted together and if you run Self Check 2 without the test plug Without test plug 1 The message A949 will appear on the display 2 This display wil change to td2 Err Because no test plug is connected 3 After a while LED tESt will be displayed and then all segments of the LCD display will come on 4 Then a series of bars corresponding to the touchpad key positions will be displayed after the message kEy tESt has appeared on screen 5 Press each keypad confirming the change of the corresponding bar to 8 on the display 6 To end the test press the PWR and OFF keys simultaneously 1 The message A949 will appear on the display 2 If the error message tdl Err or Err is displayed the data outp
98. points of your choice Following a Route NAV Mode Following a route in the forward or the reverse direction is the process by which a stored route is used for navigation The LC 90 displays navigation information to guide you from one waypoint to the next as it automatically switches from waypoint to another in sequence if the Arrival alarm has been activated and if you do actually arrive at a particular waypoint More on this point later To follow a route which you have previously programmed into the unit Get into the NAV Mode and specify the two digits designating the desired route on the third line of the display If you would like to traverse the route in the reverse order for example to return back to port press the key before typing the route number For example to follow route 02 in the reverse order type CLR 0 The third line of the NAV display should now appear as below showing Route 02 where you are now travelling between waypoints 34 and 50 Fig 34 NAV Mode Screen The selected route number is displayed on the third line followed by the waypoint numbers in the route The next waypoint is shown as the two digits on at the right hand side of the arrow Note that the LC 90 will automatically select the first waypoint in the Route plan for you to go towards from your present position Thus if the first waypoint in a Route is for example waypoint 34 then the display would show 00 34 Once you arrive within th
99. rammed magnetic variation values are the average of those in the area of approximately 10 degrees by 10 degrees Although the preprogrammed variation should be more than accurate enough for most purposes if a more accurate variation is needed enter it manually using the following procedure Manual Entry of Magnetic Variation Function 4 1 Verify that the unit is in Function 4 2 Press The A will change to a dash next to the label VAR on the top line 3 Press and then You will see the A change to a d indicating that the Automatic mode has been Disabled Now the unit has been placed in manual magnetic variation mode The cursor will automatically advance to the next line 4 Type in the desired magnetie variation followed by For example if the magnetie variation for your area is 12 degrees West the keystroke sequenee would be If however the magnetic variation is 12 degrees East then the sequence would be 1 2 ENT Since the default value standing for West variation must be overridden The MAGV indicator at the top of the display will be on whenever Magnetic bearings are in use True Bearings rather than Magnetic Bearings Function 4 If you would rather have the LC 90 display bearing in True relative to True North rather than magnetic north this can be accomplished by setting the magnetic variation in the Disable automatic mode to be zero degrees Verify that the LC 90 is in Funct
100. rd line should say On 2 Select the bottom line by pressing W 3 Press 4 Confirm that Out is displayed next to the WCH indication If not press to change the indication to Out 5 Press 9 0 3 ENTI Note that if you set the Anchor Watch alarm zone too tight that you may have to get up in the middle of the night to reset it due to minor fluctuations in the Loran signals You may need to do some experimentation to determine just how closely you want to set the alarm limit depending on your particular geographieal area Now select an open waypoint perhaps 99 in WPT Mode and store your present position there by hitting the key Go to the NAV Mode and key in 0 9 Now if you drift out of the Anchor Wateh zone the alarm will sound ROUTE FUNCTIONS PLN Mode In many cases trip from one place to another involves several course changes requiring a series of waypoints which you navigate to one after another The sequence of waypoints leading to the ultimate destination is ealled a Route The PLN Mode is used to create a Route Plan x Cf Fig 32 WAYPOINT WAYPOINT WAYPOINT WAYPOTNT You may store a maximum of 10 routes in the LC 90 and the unit will tell you how to steer along each of these routes when you call them up Routes are stored permanently in the unit s memory even when the unit is turned off Each route consists of a maximum of 10 waypoints and is given an identification number so
101. re often referred to as hyperbolic navigation systems for this reason If the master and its associated slaves were all to transmit simultaneously on the same frequency the receiver would not be able to distinguish which station it was listening to in the resulting uproar The stations therefore are arranged to transmit in specific sequence of pulses with very precisely defined time delays between the transmissions So for our simple case above where the LOP is in the middle of the baseline the time difference is no longer zero but is some Specific value of TD The receiver s job is to use the start of reception of the master signal as a reference time to start its internal stopwatch When the start of the slave Signal is detected the receiver in essence stops its internal stopwatch notes the time difference and displays it to the Operator as a TD In order to determine where one is located on any particular Line of Position another LOP is needed to intersect the first one The Loran C receiver thus must track more than one slave at the same time Most modern receivers are capable of tracking all slaves available in the chain simultaneously The interval of time between the start of the mastor transmission the series of slave transmissions and the next master transmission that repeats the whole sequence is called the Group Repetition Interval or GRI Each Loran C chain in the world has a unique GRI assigned to it and even thoug
102. red destination waypoint before the alarm sounds It also determines when the LC 90 will automatically switch to the next waypoint in a planned Route mode Setting the Arrival alarm too loosely i e with a large radius will cause the waypoint to be switched automatically too far away from the desired point possibly causing a dangerous situation You must be very careful thus when setting the Arrival alarm limit if automatic waypoint sequencing is in use A setting of about 0 1 to 0 2 n m should be reasonable for most situations For example to set an Arrival Alarm limit of 0 1 n m you would use the following touchpad sequence once you are in the ALM Mode 1 Select the bottom line by pressing W 2 Press 3 Press if OUT is showing already to change it to 4 Type 0 0 1 ENT APPROACH LIMIT wP FROM Fig 30 Arrival Alarm Anchor Wateh ALM Mode The Anehor Wateh alarm function is used to ensure that you are notified should the boat drift outside predetermined area while it is supposed to be at rest The area that defines the Anchor Watch zone is a circle within which you want to stay and the alarm will sound if the vessel goes out of the desired circle 45 Fig 31 Anchor Watch ANCHOR WATCH LIMIT Por example to set an Anchor Watch alarm limit of 0 03 n m you would use the following touehpad sequence once you are in the ALM Mode 1 Make sure the audible alarm is set The thi
103. rms WGS 72 Hange Bearing Great Circle Furuno CIF for course plotter printer seanning sonar color video sounder NMEA 0180 simple format for autopilot NMEA 0183 complex format for plotters Display Unit 0 to 50 deg C Ant Coupler 30 to 70 dep C 10 42 VDC universal 9w 119 220 VAC 50 60 Hz with external rectifier Display Unit 2 3 kg Antenna Coupler 0 6 kg COMPLETE SETS Name Type Code No Q ty Main Unit LC 90 2 Antenna Coupler AC 90C 000 041 152 1 3 Installation Materials 000 041 154 Iset DM V 000 041 155 Iset 5 Spare Parts 000 041 153 lset INSTALLATION MATERIALS Name 1 Power Cable Assy Hose Clamp ACCESSORIES UU J e _ Code BEY _ 0050120 0 000 104 058 SS7200N_ 000 570 239 _ Bracket Assy FP04 00310 7 285 420 Knob KG B2 M8x20 505304 000 800 413 Tapping Screw 5x20 SUS301 1000 800 188 Flat Washer M5 505304 000 864 128_ _ Name Type Code Qty 1 Fuse FGMB 2A 125V 000 103 165 2 OPTION Name n tfyp Code No Q ty Rectifier PR 62 AC 100V 000 013 484 B S n PR 62 220V 000 013 486 Interface Kit LC 100910 000 041 156 _4m OP 04 1 000 041 157 3 6m Whip Antenna STYLE10 3 DGE 000 572 190 1 ELEMENTARY THEOR
104. s really not dramatic Sufficiently accurate navigational accuracy for for most purposes actually could be obtained by use of any of these pairs of TD s It is merely better to use the more optimum X Y pair It is a general rule of thumb that you should be very wary of using TD pairs that cross at an angle less than 30 degrees The LC 90 will automatically select the preferred GRI as well as the preferred Slaves for the desired position without user intervention if the Automatic function is in use however you may choose to use another GRI and or Slaves in your area if available This is done by using the secondary Function 1 1 Get into Function 1 by pressing followed by 1 On the third line of the resulting display the label GRI will be followed by a flashing A indicating that automatic operation has been selected previously This must be disabled to use manual operation Press followed by a four digit code for a GRI if you wish to change the GRI also and then press ENT A d will appear replacing the A You will now have to select the proper slaves to use 2 For example if the slaves automatically selected were 27 and 43 and you wish to use 27 and 11 move the cursor down to the fifth line and hit N ENT Fig 44 Function 1 Screen 63 HOLDING THE TRACKING POINT Function 7 This is another function which is provided as an aid for servicing technicians The LC 90 tracks on the third cycle of
105. some areas of Loran C coverage it may be possible to switch to a different slave station if the one in use begins to blink but if the master station is faulty all you ean do is wait for the problem to be fixed at the station Power Failure Indicator If the main power for the LC 90 has gone off sometine during operation and if the operator hasn t noticed this the LC 90 will automatieally reaequire the Loran C signals after power is restored However there is a possibility that a tracking or acquisition error may have oceurred To warn the operator to check the position for accuracy the LC 90 turns on the PF Power Failure indieator to tell the operator that power was lost sometime in the past To extinguish this indicator press any key MANUAL CONTROL OF LORAN RECEPTION Though fully automatic the LC 90 has several manually activated signal reception controls which may need to be employed on rare occasions The experieneed operator should become familiar with these controls and their use as navigation under extraordinary conditions may demand some degree of manual Loran signal control NOTE It is strongly suggested that these manual eontrols not be used unless they are required due to especially poor signal conditions and unless they are fuly understood by the user Manual Cycle Selection Function 5 When navigating at long distances from the Loran transmitters it may become necessary to step the cycle track points forwar
106. st temporarily delete route waypoints 01 02 and 05 before calling up your desired Route plan 02 again in the NAV Mode You would use the following key sequence to temporarily delete these way points Put the unit in the PLN mode 49 2 Select waypoint 1 by pressing the down arrow cursor 3 Press Typing waypoint 01 is not necessary 4 Do the same for the next two waypoints Now when you respecify Route Plan 02 in the NAV Mode you will find that the LC 90 tells you that your waypoints are from 00 06 When you do pass waypoint 06 successfully the unit will sound the ten second long Arrival Alarm and will then switch to the 06 U7 waypoint sequence EVENT EVT Key Storing Present Position into an Event Memory Mode any except for WPT When you press in any Mode except for the WPT inode the position of the vessel at the exact moment the key is pressed will be stored in the Event memory for future reference It isn t possible to access the Event memory when you are in the WPT Mode since by definition you are concerned in that Mode strictly with Waypoint memory Up to 10 such Event locations may be saved If you try to save more than 10 locations the earliest locations will be overwritten one at a tine to onake room for the latest positions Be sure to keep a separate copy of important positions LC 90 is navigation aid it is not intended to be a secure record keeping device Press Ev T in any
107. tes in a separate log The LC 90 is intended for use as a navigational aid not a fail safe record keeping device Neither is it intended to be used without caution regarding possible dangerous naviyational situations A sequence of waypoints leading out of harbor does not take into account any vessels recently anchored nearby nor does it take into account buoys or navigation markers which may have drifted Press lt or P to get into the PLN Mode The display will look similar to the one below no LI LJ n7 Ly Lj Cl Fig 33 PLN Mode Sereen PLN The number on the top line is the route number The LC 90 is capable of storing a maximum of 10 routes numbered 01 to 10 Each waypoint in the route is shown in numerical sequence starting at 01 and continuing to 10 A maximum of ten waypoints can be stored and then observed later by serolling the display upward by one line with the W key A in the display shows that no waypoint has been previously stored there 47 Now as example let s enter waypoint 06 as the first waypoint in a Route we shall create called Route 02 First enter the PLN Mode The touchpad sequence would be 1 Press and the top line will show 2 Press 0 After ENTlis pressed the left bar on the second line will blink indicating that the cursor has automatically advanced to this position 3 Press followed by the waypoint number ENT 4 Repeat step 3 for succeeding way
108. that you are in San Francisco and that the approximate location is 37 degrees North latitude and 122 degrees West longitude The sequence of keystrokes to enter this information would be 37 00 00 N Latitude Note that the entry of trailing zeroes is optional For example you could have entered the full latitude of 370000 rather than the short form 37 if you wanted to The cursor will automatically move down to the next line where you will enter tne longitude The keystrokes for this operation are 122900 00 W Longitude Note that if the longitude were for example 22 degrees North you would have to enter the leading zero 0 022 00 00 N Latitude Note also that the default values for latitude is North latitude and West longitude If you are in the Southern latitudes or Easterly longitudes you wil need to override the default hemispherie values by using the key For example if you are located in Osaka Japan at 34 degrees North latitude and 135 degrees East longitude you would entor 4 34900 00 N Latitude CLR 1 3 5 ENT 135 00 00 E Longitude Now you should find that the cursor has automatically moved to the third line and that the A on that line is flashing This gives you the opportunity to Disable the Automatic selection of GRI and the two slave secondaries At this time we suggest that you let the LC 90 automatically select these values In a later section of this manual you will learn the
109. that you may call up any route and use it The LC 90 can automatically advance to the next waypoint on a route so you don t have to change the destination waypoint repeatedly on a voyage provided that you have activated the Arrival alarm in the ALM Mode 46 Note very well and very carefully although the Route Planning Mode is very useful and beneficial one to have available the ability to switch waypoints automatically during a voyage can potentially lead to some very dangerous situations If when using the automatic waypoint switching facility you set the Arrival alarm too loosely you can cut a corner around a waypoint leading to possible collision with other vessels or leading to a possible grounding if you come too close to land Use of any navigational aid requires constant exercise of common sense and caution Routes be used for 1 Point to point navigation steering a precise straight line between two points over which you often travel 2 Repetitive running of a complex route such as a harbor entrance channel 3 Returning to particular areas such as locations of lobster traps prime fishing spots Storing a Route PLN Mode Before entering waypoints the coordinates for each waypoint should be determined and entered in the WPT Mode See the section on using the WPT Mode In addition you should set the Arrival Alarm limit as described in the section on Alarms Be sure to record all important rou
110. the pulse The signal amplitude at this point is not terribly high so under high noise or at the extreme limits of its range the receiver may automatically track the signal at a latter cycle high SNR point If you set the Tracking Point to Hold mode the receiver tracks the signal at the correct point and you ean read how poor the SNR might be Press and the third line of the secondary Function 7 The legend Hold appears instead of Free to indicate that Cycle selection has now been frozen SELECTING OUTPUT DATA FORMAT Function 3 The LC 90 sends out to external devices such as plotters and printers the position and autopilot data through a connector on the rear panel The position data may be sent out in either Furuno CIF format Computer InterFace or in the NMEA 0183 complex format The autopilot data is sent out in the NMEA 0180 simple format To choose the format for the output data aecess Function 3 then use the following touchpad 1 Hit the down arrow key once to move the cursor down to the third line 2 Press Pressing the key will alternate the display between the following output data formats CIF for Furuno CIF Computer InterFace dSP for Display of display screen on outside terminal To be announced later 183 for NMEA 0183 data format output 3 Select the desired output format CIF or 0183 and press ENT 4 Once the key is pressed
111. the self check sequence an error messape wil be displayed on the screen Details for the meanings for these error messages are described in the Troubleshooting Section To turn the LC 90 off you must press both the PWR and keys simultaneously This specific sequence is necessary in order to prevent you from inadvertently turning off the unit by accidently pressing the key If this were to happen you would have to wait another five minutes or so after power is turned on again while the unit acquires and locks onto the signals INITIALIZING THE NAVIGATOR FOR YOUR OWN GEOGRAPHICAL AREA The LC 90 is designed to retain in memory all information necessary for operation whether it is turned on or off An internal keep alive battery performs this function Once the LC 90 has been initialized for your area you need do nothing more than turn the power back on when you want to set out on a new voyage As smart a unit as the LC 90 is it still needs to know approximately where it is located in order for it to home in on the correct Loran signals for that area Thus the first time you use the unit you must initialize it for your geographic area From then on unless you wish to override its automatic selections the unit wil determine the exact position automatically You must enter your approximate location within about 3 degrees although you may have to be more accurate than that if you are located in an area close to a baseline extension In t
112. treatment doesn t do the trick Color TV s One other particularly nasty interference source is the typical home grade color television although sometimes a regular black and white TV wil wreak havoe on Loran C reception Unfortunately the only solution to this sort of interference is to turn the offending TV off or else purchase a commercial grade TV receiver which is better shielded than the home quality units HOW TO COMBINE WITH AUXILIARY EQUIPMENT The LC 90 provides a data output connector on the back panel This is used for connection to peripheral equipment such as a position plotter a printer or an autopilot Position data is sent outside the LC 90 in one of several different data formats a Furuno CIF Computer InterFace for Furuno peripherals b NMEA 0183 Complex Format for plotters c NMEA 0180 Simple Format for Autopilots An optional connector cable kit LC 1091 Furuno Code No 000 041 156 is needed to access the output data The interconnection diagram is shown on the next page 24 RCN6A 6 0P UNUSED CORES amp SHIELD el SPTF sRCN6A 16 10P H OP SHF AA a d GD 17 Fre HQ GD 2000 me rikaq USPOOS2 i 4 We i VIDEO ea AUTO O s rot FAP 20 PILOT Oye M papi d COMPASS 1 FCD o AUTO PILOT H yor FAP 301 P A UNIT l idi
113. u should use a capacitor rated for no less than 32 32 2 or 48 Volts A 50 V D C unit should suffice This capacitor should be a computer grade unit that has internal vents in case it should overheat and possibly explode and the capacity of the electrolytic capacitor should be about 10 000 microfarads or so careful to observe the polarity of the capacitor Reverse polarity wil destroy the capacitor and could damage the charging system as well The positive lead 23 of the capacitor is connected with a short lead less than 4 inches long to the Output terminal of the alternator using a large crimp lug to go under the terminal in parallel with the heavy lead going to the battery bank The negative terminal of the capacitor should go to a mounting bolt used to Secure the alternator to its mounting frame This lead also must be kept shorter than 4 inches or so in order for the capacitor to do its job Do Not connect the capacitor to the Field terminal of the alternator at the risk of destroying the alternator itself Hopefully the electrolytic capacitor will do the job for you and if that is the ease you can proceed to mount it securely to the alternator perhaps by using tie wraps Make sure the capacitor isn t able to move around under vibration sinee the leads could be broken off If you have any doubts about what you are doing it is time to call in a qualified electronics technician especially if the simple capacitor
114. uld be a greater ehange in position than for the W TD s Obviously the smaller the position shift for given change in TD s the better the accuracy we can expect in determining our exaet position 02 There is however a fly in the ointment While the W slave station would be a better choice on the basis of gradient alone in the area we are considering near Yokohama the station is located farther away then the Y slave which would otherwise be chosen to cross with the X TD s The W signal thus might be weaker and thus less reliable than the Y signal even with the less desirable gradient characteristics of the station However stations sometimes will go off the air for scheduled maintenance or because of a problem At these times it may be necessary to choose manually another slave station in spite of the fact that it may show less than optimum geometry or signal strength in your area Angle of Crossing In an ideal Loran C world all TD s would cross at an angle of 90 degrees Unfortunately we don t live in such a world so we must consider the angle of crossing that actual TD s create The closer the angle of crossing is to a right angle the better the accuracy of positioning will be Close examination of Fig 1 shows that the X and the TD s cross at a better angle than do the X and the W TD s or the W and Y TD pair and thus are a better choice to use Note that the differences in angles of crossing of the X Y X W and Y W pairs i
115. ut circuit is likely to be faulty Replace the CPU board 3 Now follow the steps 3 through 6 above Remember that an unusual symptom may be caused not only by a faulty circuit but also by Loran C signal conditions or even operator error 66 1 Signal Interference Quality Signal quality is very important in determining the exact point at which the receiver locks onto and tracks the signals A poor signal causes erratie indications and tracking may occasionally be interrupted The signal quality can be checked with the CYC SNR indicators and the SNR ECD display Select another secondary or chain if it is confirmed that the signal is too weak or distorted Defective Loran Transmitters The BLINK warning indicators are provided to indicate the condition of the transmitting stations The warning indicator comes on automatically when abnormal conditions exist of one or more stations Inadequate Unit Installation The performance of LC 90 largely depends upon its installation especially antenna loeation grounding and noise suppression This problem will probably require the assistance of your dealer Improper Operation This requires the operator to consuit the instruction manual or ask dealer for assistance The following pages contain lists of specific symptoms and remedies SYMPTOM POSSIBLE CAUSE REMEDY Nothing appears 1 Switch at main switch 1 Turn on the main switch Display doesn t compl
116. value of these TD s will change depending on the GRI in use by the LC 90 at that moment The important thing to remember is that the LC 90 stores positions in L L format in its waypoint memory and that an L L position 33 of zero zero degrees indicates that the waypoint is empty Fig 17 WPT Mode Screen 2 Now respecify the waypoint to be waypoint zero seven Use the following touchpad sequence CUR 0 7 ENT Note that the entry of tne leading zero is necessary Entering 7 after CLR wil simply cause the LC 90 to ignore the input as invalid If waypoint zero seven is presently empty you will see zeroes lines four and five Now go ahead and enter the San Francisco numbers the cursor has automatieally advanced to the next line after you hit 3 3 3 8 30938 00 N 122 24 00 W Note that the entry of trailing zeroes is optional The LC 9U senses when trailing zeroes are necessary and adds them needed you may hit the key to see what TD s correspond to the L L you just entered Note also that if we were operating in Southern Latitudes and Easterly Longitudes we would have to override the North and West defaults that the LC 90 has been normally set up to use For example if the position of our Waypoint zero seven were 37 degrees 40 00 minutes South Latitude and 122 degrees 24 00 minutes East Longitude we would punch in the following sequence 8 37238 00 3 4 122924 00 E M
117. ver thinks it is tracking on the correct cycle and 1 indicates that the receiver suspects that it is tracking on the wrong cycle For example in Fig 37 the slave 1 signal is shown as tracking on the wrong cycle ECD Function 6 The definition of ECD is Envelope to Cycle Difference This refers to the distortion of an actual pulse received off the air as compared to the theoretical shape The LC 90 can display a relative indication of the magnitude of the problem by using Secondary Function 6 Deviation Function 6 The amount that the internal reference oscillator in the LC 90 has drifted from its preset value is called the Deviation The LC 90 compares the frequency of its own internal oscillator with that transmitted by the Loran C stations all of which have extremely precise master oscillators 54 The nominal value for DEV is 000 set at the factory If the oscillator drifts too far signal acquisition time may increase and tracking accuracy may be affected If this should occur the unit must be serviced The first table below lists the numerical values for ECD and the second table lists the numerical values for DEV ECD and DEV Table ECD DESCRIPTION CYC DEV READ ING READ I NG IND ICATOR 17 Tracking on earlier cycle Less than 99 16 to 11 Signa distorted or more than might be tracking 99 pd on earlier cycle 10 fo 10 Tracking on correct 11 TO 16 Signal distorted il might be tracking on later cycie

Furuno LC-90 User's Manual

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