Cambridge GPS/NAV Flight Recorder v5.1
Contents
1. th point of the A task The task distance to this point is always zero Find the start point you want There is no need to press the GO key You have just selected the start point of your task Press the RIGHT arrow key again Now you can choose Al the first turnpoint of the A task The distance from AO to Al is shown at the bottom of this screen Press the RIGHT arrow key again for the next turnpoint Get the idea The distance shown is always from the start point to the selected point To clear out a task go to the zero th point and scroll to the Select v message If you just keep on scrollin the task is saved But the task is cleared if you exit this screen with this message shown Declaring and Starting the Selected Task The GO key is used to exit Task Selection screens On the way towards the exit you must make two choices The first choice is about Declaring the task A declared task has date and time attached to it The Declared task is attached to the Flight Log file in the PC This permits Official Observers to see if you declared your intentions before takeoff You may want to edit a task without declaring or starting it The GPS NAV design is clever enough to give you just the right choices GPS NAV Version 5 Page 19 2 10 97 The Main Flying Screen On Task TP 0 a sugarbush Task C Declare No Task C Start Yes Dist 51 2 GO Dist 51 2 Any Task C Selection Screen2. 10 97 Bend this end if you use Bend this end if you use the hole on the case edge the hole on the case bottom Cam bridge P N FA 264 eee e N Bend lines defined by Je close spaced holes Figure 10 GPS NAV Model 20 25 Mounting Bracket GPS Recorder case N wi Mounting Bracket Note orientation of mounting bracket recess 1 4 20 Plastic mounting screw Figure 11 Detail view showing anti rotation recess in Model 20 25 Mounting Bracket The Model 20 25 mounting bracket lets the pilot mount these GPS Recorders in an astonishing variety of ways The bracket can be bent only once by hand using the pre drilled line of holes Note that the two ends are not the same Use the narrow end with the Model 25 on the side of the cockpit The Model 20 uses the wide end in most situations GPS NAV 5 Page 35 2 10 97 Power Cable Wiring There are 2 GPS NAV cables for which the pilot needs to know the wiring These are the power cable and the NMEA 0183 connection to an S or L NAV or other piece of equipment using real time GPS data It is vital that the cable connectors be attached with the correct orientation Please refer to the diagrams shown below Power to the Model 10 is supplied through the red and black wires in the 4 wire cable Note Use Ferrite RFI Bead on the power cable Model 20 25 power control is more complex Un switched power using the Red wire means the GPS NAV is turned on a
3. An active task can now be edited Distance from the beginning of the task is shown for each intermediate turnpoint A trial P O S T task can be started without declaring it 5 Simplified Navpoint Editing Attribute and ID are now shown in point editing screens 6 Improved Circling Wind Algorithm The circling detection algorithm is now more sensitive and reliable 7 Error Detection and Correction for Navpoint database Some GPS NAV instruments developed navpoint database errors when power was cycled rapidly Critical navigation data is now stored in two locations Error detection and correction algorithms ensure reliable navigation data 8 Transmission of task data to L NAV and NAV GPS NAV Version 5 0 transmits the active task to an L NAV or S NAV This makes it possible to compute altitude required to glide home around an intermediate turnpoint GPS NAV V4 8 does not have this feature GPS NAV Version 5 Page 4 2 1 0197 The instrument and its associated PC software are approved by the IGC for FAI Glider and Motorglider Badge and Record flight documentation As of October 1996 tasks may be declared electronically using the GPS NAV A Walking Tour The quickest way to learn the Cambridge GPS NAV is to walk around with it Attach a 12 Volt battery Model 20 amp 25 connect the LCD display with the supplied test cable and press the LCD display ON key The LCD should show a sequence of messages If it does not make sure it
4. is attached to the correct port GPS Display on the instrument You should also note that the green GPS lamp is on continuously rather than blinking This means there is not yet a GPS fix of your present position When a GPS receiver is moved to a new site more than 300 miles away from where it was last used it can take up to 40 minutes to acquire the satellite orbital data required for its initial position fix Also GPS does not work indoors Orient the antenna so it has a good view of the sky While waiting for the GPS receiver to wake up and smell the roses take a look at the various LCD screens Screens are arranged in Rows and Columns Use the Primary Screen Map on page 2 as your guide LEFT and RIGHT arrow keys move to the top row of a new column UP and DOWN arrow keys move to new rows within a column or change information within a screen Pressing the GO key several times always finds the Main Flying Screen This is the screen you will use most of the time GPS NAV Version 5 Page 5 2 10 97 Turn Indicator proportional The Active navpoint to Bearing Track Navigate to Sugarbush Bearing to the navpoint lt a degrees magnetic Brg 095 135 Trk Distance to the navpoint 3 pist 35 2 soe x Engine Run symbol Glider Track over x the ground of satellites acquired Figure 1 The Main Flying Screen If you are technically inclined or just bored waiting for satellite acquis
5. named and new points can be added without using a PC With Versions 4 8 and 5 navpoint deletion can only be done in the PC This keeps Mr Murphy and his law from zapping critical data at the wrong time Navpoint editing uses two additional groups of screens When Edit Points is displayed pressing GO branches to the first group As usual the LEFT and RIGHT arrow keys are used to select the desired screen The choices are edit an existing point create a new point or simply Exit to the Navigate to Screen Edit Points Create Point Edit Point K IATeRER 27 8000 Figure 7 Point Editing Screens In the Exit screen pressing GO returns to the Navigate to screen In Edit Point the UP and DOWN keys find the point of interest arranged by ID GPS NAV Version5 Page 416 2 10 97 In Edit Point and Create Point screens pressing GO branches to a second sequence of 7 detail screens for editing the selected point Edit Name Edit Lat Edit Long Edit Elev Edit ID Landpoint Turnpoint The starting point is Name The default name for a freshly created point is NEW At the start of editing there is an underline cursor beneath the first letter of the name The UP and DOWN arrow keys scroll through all possible letters for this location The LEFT and RIGHT arrow keys move the cursor left and right in the Name Latitude and Longitude screens For a newly created point the GPS NAV assigns the last known GPS receiver
6. poBbueue syujod ouelsip Ayjeonoqeudye JSE A IA 1 O Bunip B5unoej s p 0uns i pue Aq pobuee peBbuewe NMOG 10 df SS ld 40 Julod payew qepue sjuroduiny sjulodusny yulodusn yuiodaeu 9saioe Agua oy S SIUL JO JS U L JO SH ul JO 3S4 OUL yse x u sul u3934 soui SUL 8 0 sia 8 O s0 6 OF sa T S sa 9 ST WG g6z ei gez Sa eco gi 70 5a ezz Ba UOT ROSTES ysnqaebns usnqaeins z praT g 420dmen TazSayooyd YSeL squtodpueqy eoueysta san feqeudtw saz tar SVL qUTOd 4seT NAV Guide Version 5 Page 2 2 97 GPS Introduction The GPS Navigator amp Secure Flight Recorder GPS NAV has three components the Flight Recorder containing the GPS Receiver the LCD Display and software for an IBM compatible Personal Computer PC Connection to a Cambridge NAV computer is also provided The Flight Recorder can be used with or without the LCD display It records 9900 GPS fixes Flight Logs are transferred to a personal computer using a serial data cable Gliding needs different navpoint data than most types of aviation This is why GPS NAV navigation data originates in a PC database program rather than the GPS NAV itself New Version 5 PC software tools make it easy to construct custom navpoint databases for the GPS NAV from large National Databases Thanks to John Leibacher and many other volunteers an amazing source of turnpoint databases can be found at http acro harvard edu SSA JL TP HomePag
7. position to simplify Latitude Longitude and Elevation entry New points are arbitrarily assigned ID numbers starting with 8000 Markpoints are assigned ID numbers starting with 9000 This makes it easy to find these classes of points when they are arranged by ID number The GPS NAV assigns an internal hidden index number for each point Thus two points may have the same Name ID and position without the GPS NAV being confused However transferring waypoints to the PC database does require unique ID s so it is best to assign a different number to each waypoint These screens also allow Landpoint L and Turnpoint T attributes to be assigned for each waypoint Landpoint means the point is suitable for landing The Landpoint attribute makes the point show up in the list of Landpoints arranged by distance Turnpoint means the point can be selected for a task and will show up on the PC screen If no attributes are assigned the point is simply called a Waypoint W Pressing the GO key from the detailed point editing screens stores the new or edited point in the GPS NAV database GPS NAV Version 5 Page 17 2 10 97 Selecting and Editing Tasks A sequence of Turnpoints is called a task The GPS NAV can store up to 10 tasks with up to 9 turnpoints per task Stepping through a sequence of task points is quicker than searching through the navpoint database each time you arrive at a turnpoint GPS NAV Version 5 simplifies task functions S
8. short beeps and the display shows Close to in place of Navigate to When the glider gets nearer the turnpoint the recorder gives one long beep and the display changes to Arrival The GPS NAV is silent as the glider leaves the turnpoint but the pilot may beep or cheer as the spirit moves The radius at which each message appears is configurable See the PC software Users Guide for details If the GPS NAV LCD Navigate to screen is not visible the letter M for Message will appear on the screen Pressing GO returns to the main navigation screen where the message Close to or Arrival is visible Messages and Sounds in Restricted Areas The GPS NAV warns the pilot as a restricted area is entered In the PC Navpoint database a point with an R attribute is assigned a radius a bottom and a top altitude The restricted area is a cylinder with these dimensions surrounding the R point Restricted points are listed on the Landpoints screen in order of distance from the current position When the glider enters this area the GPS NAV gives 4 short beeps and the display shows Restricted in place of Navigate to While the glider is inside the circle the Restricted message overrides all other messages on the Main Flying Screen Inside restricted space the audio warning is repeated every 10 minutes The GPS NAV warning happens at the exact boundary of the restricted area Careful pilots will choose restricted area dimensions slightly larger tha
9. the GPS NAV guide you back to your Thermal GPS NAV Version 5 Page 7 2 10 97 You must walk faster than 2 Kts 3km hr to see the Track number and the Turn Indicator You will quickly learn to interpret the graphic arrow as well as the track and bearing numbers You can measure your velocity by pressing the UP key The Brg number changes to velocity V and the first line changes from Navigate to into the date and time UTC the thermal was marked As always press GO to return to the Main Flying Screen This completes the walking tour The basic concept of screens and use of GO and arrow keys have been described Screens are consistent in design labelling is clear and keys always work the same way This means GPS NAV functions can be mastered by simply trying them Most users can quit reading here install the GPS NAV and go flying without further delay But if it is raining feel free to read on Bearing Heading Track and the Turn Indicator Waypoint North Bearing 22 Track 30 Heading 45 Figure 3 Definition lt Wind 90 of GPS Navigation Terms Angles are defined relative to Magnetic North Bearing is defined as the angle of the line between the glider s position and the waypoint Imagine the shadow of the glider tracing a line on the ground The angle of this imaginary line is the gliders Track Heading is where the nose of the glider is pointed A compass shows Heading Crosswinds mak
10. Figure 9 Declaring and Starting a Task The first choice is about declaring the selected task The default setting is No Change the choice with the UP or DOWN key and press the GO key again If Yes is chosen the following message appears for 2 seconds Task C is Declared The second choice is to start the selected task Again the default setting is No If Yes is chosen the message Navigate toon the Main Flying Screen changes to On Task TP 0 The Task Turnpoint number O in this case advances as new task turnpoints are selected New task turnpoints are selected from the Task Management screen two screens to the right of the Main Flying Screen It shows the next turnpoint by name and number As with any other navpoint selection screen pressing GO makes it the active navpoint The current Task can be reviewed by scrolling UP or DOWN in the Task Management Screen The choice to stop a task is also available here Tasks are flexible For example it is OK to select non task nNavpoints such as Thermals or Landpoints In this case the Task Management screen will show Resume Task Pressing the GO key re activates the task Of course a task is also resumed whenever the next task turnpoint is activated using the normal navpoint selection lists GPS NAV Version5 Page 20 2 10 97 Messages and Sounds near Active Navpoints The GPS NAV provides extra help near the active waypoint As the glider approaches the waypoint the recorder gives two
11. The Cambridge GPS Navigator and Secure Flight Recorder User s Guide Models 10 20 and 25 Recorder Version 5 LCD Version 5 ON saat ss NAS Sma a E Navigate to Sugarbush lt a S6 b TY lt m je l wy xx Xxx Cambridge Aero Instruments RR Box 109 3 Warren VT 05674 USA 44 07 05N 072 49 62 W Tel 802 496 7755 FAX 802 496 6235 466 Aseniqo4 G_ UOISJOA dew ueeisg Mewud AVN SdO 4L OD ssoud uay OD sseid usy aw pue ayeq u9 j9S SI O s pnyye JUSIDIP H P s ol NAOG H P A s OJ NMOQG Hog uonisOd sunal SAEME ye pum 988 0 JO df Buissasd JO qn Buissoid I8A94 punos soyayes ieulo 09 Buiss Jd NMOG 40 df 888d Aq yeuuey Aq juiod peywew epnyypy aunssaid Woy eyep oes sjulodaeu yulodAem oanoe epnyye Siul ye au 0 JeBIAPeN e o ayebinen pmniv Sd9 0 NMOQ SS91d Bunea pue y SMOYS u99J9S PUM SMOUS UJS teunoy e yew yulod e yew apnyibuo7 s 0 snJe1 s 194190994 Bupa J10 juiod Bully uen eu PUI BUDO SUL o 3194 OD SSAg O BION O9 SSAd BWOYNMOG SSG Sd9 oss Agua oy S sul ose 9 97 3510 VL LET GeT Bla STTTW 380d o3 a zebTAeNn eoo eee g oz sa WL LET GET Sa u STITH 380d LZ O c PUTM N T8 90 ht S ep5ts S Nud pn 3e 8 9 XTA AE s ufod 3Tpa Tewr yr STU HIeN I quroda STU JITEN syse Bues oue sip Aq sjurodusn pue Buue o p
12. a type NP 12 12 Volt 2 0 Ah Battery fuse 2 Amp Slow Blow Backup battery w C Lithium coin cell Recorder fuse type BR 2325 2 Amp Slow Blow Figure 8 GPS NAV Model 10 Battery and Fuse Locations Note Disconnect Main Battery before changing fuses Note The Recorder seal is broken and Flight Logs are lost if the backup battery is removed with the Recorder turned off Turn Recorder ON during Backup Battery replacement GPS NAV 5 Page 26 2 10 97 GPS NAV Model 20 amp 25 Backup Battery and External Supply The Model 20 amp 25 GPS NAV rely on the Glider s battery for electrical power during operation A lithium back up battery is used to preserve flight recordings when power is removed It also preserves the permanent electronic seal which prevents tampering When the output of the lithium battery drops below 2 0 volts it should be replaced The lithium battery is located under the flat plate antenna on the GPS NAV Model 20 On the GPS NAV Model 25 the battery is under the side cover plate Note Before replacing the lithium battery be sure to turn the GPS NAV on This will prevent the permanent electronic seal from being broken Note It is important to keep power supplied to the Model 20 amp 25 GPS NAV during Flight For gliders with 2 batteries switching between batteries must be done quickly to avoid removal of power to the GPS NAV We recommend two separate battery switches This way battery 2 can be con
13. automatically computes both wind speed and direction during circling maneuvers Each wind measurement takes about 2 minutes Circling must continue un interrupted during this time Accuracy improves with continued circling Note that wind direction may be inaccurate when wind strength is very low Wind is shown on the display screen just to the left of the Main Flying Screen Wind 325 24 Sugarbush Brg095 135 Trk Dist 35 2 eee This screen shows direction and strength of the wind measurement closest to the current altitude This screen shows complete wind information The second line shows the altitude 3500 at which the measurement was made The second number on this line shows the time 47 minutes since the measurement was made Wind 325 24 3500Ft 47m lt a Brg 095 135 Trk Dist 35 2 333 Figure 6 Wind Measurement Screens Wind varies with altitude and time The GPS NAV stores and organizes wind information at 300 metre altitude increments The UP or DOWN arrow keys are used to scroll through all available wind measurements GPS NAV Version5 Page15 2 10 97 Creating and Editing Navpoints The best way to get the navpoint database so essential to GPS navigation is to transfer it from the PC using software supplied by Cambridge Please refer to the PC software User s Guide for more information The GPS NAV also has limited built in navpoint editing This means markpoints can be
14. battery drops below 11 volts it is discharged The GPS NAV shuts itself off when the battery drops below 9 5 volts The glider main battery can be connected to the Model 10 GPS NAV Power is drawn from the battery with the higher voltage This improves reliability if the GPS NAV battery fails When the external glider battery has a higher voltage than the internal battery External Battery voltage is also displayed in the message sequence The Recorder will work with external power even when the internal battery fuse has failed The GPS NAV is supplied with a 12 Volt 300mA battery charger With the GPS NAV turned off about 12 hours are required to completely re charge a discharged battery Since overcharging will shorten battery life the charger should not be connected for longer periods A typical discharged battery will charge at more than 300 mA while a charged battery takes less then 150 mA Charging current is shown in the power on message sequence when the charger is connected If the Battery charge lamp fails to blink or the charge current shown on the LCD display is zero check charger wiring and the battery fuse under the bottom cover GPS NAV 5 Page 25 2 10 97 The backup battery preserves the Flight Log even when power to the Recorder is turned off The output of a new backup battery is about 3 volts and it should last about 5 years When its output falls below 2 0 volts the backup battery should be replaced Main battery Yuas
15. creens show signal strengths below 40 The antenna is in a poor location Antenna location is critical to performance GPS signals have no problem going through the fiberglass used in a glider fuselage skin Plexiglass canopies are also transparant to GPS signals However thick fiberglass such as a spar will cause problems A carbon fiber fuselage will block the GPS signal Also a metal frame panel or even pushrods may cause problems The Recorder always takes a long time to acquire satellites If the Recorder is turned on before the antenna is attached or in a location where the sky is obscured it may go into search the sky mode This takes up to 40 minutes Turn power off and on again when signals are available This will shorten acquisition time The Recorder switches between 2D and 3D navigation Flight recordings show high EPE Track Trk and ground speed V numbers are erratic The antenna is not working properly The receiver will normally acquire between 6 and 8 satellites during flight It should usually see more than 5 satellites If this is not so check the antenna mounting location GPS NAV 5 Page 29 2 10 97 The graphic Track Error Indicator and the visual location of an active waypoint do not agree The Indicator seems to guide me in the wrong direction This is normal You are seeing the effect of wind The gliders heading will crab into the wind This points the nose of the glider away from the goal In a strong
16. ctive See the Installation Guide for the correct way to put connectors on the flat cable Check for proper operation using the test cable P The display lights up but shows Navigate to No Points A Either there are no waypoints in the Recorder database or the cable between display and Recorder is defective To check for a bad cable see if the UTC clock is running The clock is shown in the Latitude screen list The internal GPS engine keeps time even when there are no visible satellites If the clock is running the GPS engine and Recorder are functioning and the Recorder Display cable is OK GPS NAV 5 Page 28 2 10 97 The GPS Recorder always shows zero satellites That is no satellite annunciators are visible in the Navigate to screen and the Status screens show O n on the top line If the GPS receiver is OK this means no signals are being received from the antenna There are several possible reasons for this L The 1575 MHz GPS signal does not pass through buildings so GPS doesn t work indoors 2 The coaxial antenna cable may be defective Check reception with the antenna attached directly to the Recorder Twist on BNC connectors are not as reliable as crimp on types Check continuity of the coaxial cable center conductor with an ohmmeter 3 The antenna may be defective This is a rare occurance The GPS lamp on the Recorder never flashes One or two satellites are visible Satellite Status s
17. e Track and Heading different GPS NAV Version 5 Page 8 2 10 97 The GPS receiver computes its position every 2 seconds Even though position is only known for sure to within the Estimated Position Error typically about 100 meters positions determined 2 seconds apart are very accurate relative to one another This means the GPS receiver can measure the gliders direction of flight the Track and its true ground speed V with high accuracy This is done by calculating the angle relative to magnetic north between two fixes for Track and dividing the distance between two fixes by time for V GPS navigation is simple It is no longer necessary to worry about glider Heading as indicated by the compass Without GPS the pilot has to guess the crosswind and then crab into it to fly the desired Track With GPS Track itself is measured accurately so there is no need to estimate crab angles etc When Track and Bearing are the same the glider is heading directly to the waypoint The GPS NAV shows both Bearing and Track in the Navigate to screen Bearing Track Track Error Positive Track Error means the glider must turn right to fly towards the navpoint Glider pilots have little time for arithmetic while racing So the GPS NAV has a graphic Track Error Indicator When the Indicator is centered the glider is flying directly to the active navpoint This is true even with crosswinds A glance at the graphic Indicator shows which way and h
18. e html Navpoints are sent to the Flight Recorder using the serial data cable With navpoint data in the Flight Recorder the GPS NAV display provides navigation information The unit can also mark its present location and navpoints may be created edited and saved in the GPS NAV database Bearing and distance to a waypoint ground speed and track are sent to an attached Cambridge S NAV or L NAV GPS related functions of these NAV computers are described in their documentation Version 5 Firmware Additions and Improvements This list covers only improvements made since Versions 4 1 and 4 6 1 Automatic variable rate logging Logging intervals can change automatically from 2 to 60 seconds Logging changes to the minimum interval near the active navpoint Two minutes of fast logging is also activated by pressing the ON key This feature extends flight logging to 16 long flights Maximum total flight time is now more than 120 hours GPS NAV Version 5 Page 3 2 10 97 2 Task entry from the PC Up to 10 tasks A J can be defined in the PC navpoint database editor Tasks are transmitted to the GPS NAV with the navpoints 3 Fast scrolling of large Navpoint databases Any of the 250 navpoints in the database can be selected in less than 7 seconds The secret is to tap the UP or DOWN arrow key quickly This jumps past 9 navpoints 4 Simplified Task editing Task selection editing and declaration are now done in one group of screens
19. electing choosing editing and declaring tasks are all done at the far right end of the Primary Screen Map The entry point is the Task Selection Screen Task Selection Select Task Turnpoint A0 Turnpoint Al Turnpoint A2 A i Sugarbush _ Morrisville im Jay Peak Dist 302 5 Dist 0 0 Dist 51 2 Dist 94 0 Select Task B Turnpoint BO Turnpoint B1 Turnpoint B2 a Sugarbush Morrisville cd Sugarbush Dist 0 0 Dist 51 2 Dist 102 4 Dist 102 4 Select Task Turnpoint C0j Turnpoint Cl Turnpoint C2 c y Sugarbush Morrisville Select v Dist 51 2 Dist 0 0 Dist 51 2 Dist 51 2 Figure 8 Task Selection and Editing Pressing the right arrow key again and again eventually gets to the Task Selection screen Pressing GO selects Task A The DOWN arrow key selects Task B and so on to Task J Total distance for each Task is shown on these screens GPS NAV Version5 Page 18 2 10 97 Task creation and editing is simple compared with older versions of the GPS NAV As an example start with no tasks in the GPS NAV On the Edit Task a screen press the RIGHT arrow key You will see the message Turnpoint A0 Select v This is a gentle hint to select a turnpoint using the UP and DOWN arrow keys If you take the hint you will see turnpoints arranged on a circular scroll in alphabetic order The Select v message occupies the slot between Z and A Note that the start point is the zero
20. ficult but not impossible The Model 10 Recorder is intended to fit where a Barograph would go Models 20 and 25 are about the same size as a 35 mm camera and use the same mounting screws Don t try to install the GPS NAV when the weather forecast is for a 300 KM soaring day You will get very frustrated The GPS NAV display mounts in a standard 57 mm 2 1 4 diameter instrument panel hole The 4 long 3 mm threaded mounting nuts hold the display in place Use a piece of standard plastic instrument tubing to hold the nut when the threaded stud on the display is hard to reach The nuts can also be used to mount the display in front of the panel This will make the display easier to reach in some gliders If there is no room in the instrument panel the special bracket supplied by Cambridge mounts the display to the canopy rail or other parts of the glider cockpit There are many ways to bend this bracket depending on the specific glider and the desired GPS NAV display location Tilting the display up about IO will let more light fall on the LCD and improve its contrast We strongly suggest making a heavy paper model of the bracket as a guide before bending the actual aluminum part The bracket can be attached to to glider fuselage with several 3 mm 4 self tapping screws Bend Line for i _ _ Glider fuselage display mounting I f g mounting holes Mounting Holes Bend line for attachment for LCD dispiay to glider fusela
21. ge Figure 9 GPS NAV Display Mounting Bracket GPS NAV 5 Page 33 2 10 97 The GPS NAV Model 10 mounting system consists of the black painted Mounting Bracket P N FA 245 and the Backup Plate P N FA 246 Attach so the glider fuselage part is sandwiched between bracket and Backup Plate We have personally done more than 100 different installations so contact us for advice and psychological counseling The GPS NAV Model 20 has a built in flat plate antenna covered by a black plastic radome The antenna must have an unobstructed view of the sky there are three favored locations for the model 20 1 On or under the instrument panel top cover Mount the GPS NAV as close as possible to the canopy It is OK to put the unit under the cover as long as it is not constructed of carbon fiber or metal 2 In the same location as your obsolete 35 mm turnpoint camera 3 Behind your head near the top of the fuselage This works when the top of the fuselage is not made of carbon fiber GPS signals will not pass through people so position the antenna above your head The GPS NAV Model 25 is for desperate pilots with impossible gliders It combines the small size of the Model 20 with the separable antenna of the Model IO Note that the antenna mounting bracket supplied with the Model 10 and 25 has mounting holes which match microphone bracket mounting holes in many gliders The Cambridge difference is in the little details GPS NAV 5 Page 34 2
22. headwind the Indicator will be very sensitive because it relates to Track and not Heading GPS Recorder distances are slightly different from those calculated by the PC software This is normal The PC software uses the Great Circle method The GPS Recorder uses rectilinear coordinates This gives fast updates and is optimum for in flight navigation These numbers should not be used for calculation of badge and record distances Distances shown by the GPS Recorder are very different from map distances The maximum distance which can be displayed on the GPS Navigator is 1400 NM or 2700 Km The Recorder and the map may use different units for distance The Recorder is configured by the PC software for one of 4 different units systems They are Nautical Miles feet knots Kilometers meters kilometers hr Kilometers feet knots Statute miles feet knots GPS NAV 5 Page 30 2 10 97 Specifications Size Weight Power Fuses Voltage Indicator Model 10 with mounting bracket Model 20 with GPS Antenna Model 25 with BNC Connector LCD Display and control unit Model 10 Model 20 or 25 LCD Display and control unit Model 10 Model 20 or 25 LCD display Model 10 Model 10 GPS NAV 5 Page 31 6 2 158 mm long 6 2 158 mm wide 3 1 79 mm height 4 7 120 mm long 2 7 68 mm wide 2 3 84 mm high 5 5 140 mm long 2 7 68 mm wide 1 9 74 mm high 2 6 66 mm heig
23. hen this input goes low the GPS NAV will turn off in 32 seconds Wire color Blue Yellow Green Red s Black White Part Name Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Datacom Power Serial data NMEA 0183 Logic Control Input to Output from Ground Switch Recorder Recorder Input Blue Wire this side Blue Wire this side Use 6 conductor Modular cable with 2 Ferrite RFI Suppression beads GPS NAV5 Page 37 2 10 97 Display Cable Wiring Blue Wire this side Blue Wire this side GPS Display To GPS Flight Recorder Display wiring for single seat gliders Blue Wire this side Note Rear seat plug of cable between front and rear LCD has reversed orientation Front Cockpit Blue Wire this side To GPS Flight Recorder Display Rear Blue Wire this side both ends Cockpit Display wiring for 2 seat gliders GPS NAV 5 Page 38 2 10 97
24. ht and width 0 47 12 mm in front of instrument panel 0 80 20 mm behind instrument panel Fits standard 57 mm panel opening 3 6 Ibs 1 64 Kg 0 8 Ibs 0 36 Kg 0 35 Ibs 0 15 Kg Internal 12 volt or external 12 14 volt battery Current drain 220 mA with 1 LCD display External 12 14 Volts or power supply Current drain 160 mA with 1 LCD display Second seat LCD adds 10 mA to current drain Recorder Battery 2 Amp Slow Blow 2 Amp Slow Blow 1 flash 10 second repeat 2 flashes 10 second repeat v lt 10 75 10 75 lt V lt 11 25 3 flashes 11 25 lt V lt 11 75 4 flashes 11 75 lt v lt 12 25 5 flashes 12 25 lt V lt 12 75 6 flashes 12 75 lt V lt 13 25 2 10 97 Charger Power Supply Charge Model 10 LED Logging Interval Maximum Flight time Altimeter Means of Propulsion moP Engine Run detector 12 volt DC 300 mA Center pin negative 0 flashes 0 lt lt 50 mA 1 flash 50 lt lt 150mA 2 flashes 150 lt lt 250 mA 3 flashes 250 lt lt 350 mA Note Charge current flash is longer than voltage flash 4 seconds minimum up to 32 seconds PC configurable 11 hours at 4 seconds logging interval Temperature compensated piezoresistive sensor Range 36 000 feet Resolution 30 10 meters feet at sea level Calibrated microphone GPS NAV 5 Page 32 2 10 97 Installation Guide Gliders were designed without regard to GPS receivers This makes installation dif
25. information for all stages of glider pilot training Version 5 firmware adds two new features to GPS NAV flight recording 1 The GPS NAV Arrival message and its asociated acoustic warning are now synchronized with logging This means you can leave a turnpoint as soon as you see the message or hear the long beep 2 The pilot can select short and long logging intervals in the PC software The range is 2 to 60 seconds The long interval is used far from the active navpoint As the glider approaches the arrival radius of the active navpoint the logging interval is reduced automatically to the short value 15 fixes at the short logging interval begin whenever the ON key is pressed GPS NAV Version 5 Page 22 2 10 97 Flight Log Security The design of the Cambridge GPS Navigator and Secure Flight Recorder guarantees integrity of Flight Logs Several mechanisms are used The first is to append a digital Signature to each Flight Log If the Flight Log is modified in any way its Signature changes in a way that is virtually impossible to decipher The Cambridge GPS NAV system permits Flight Logs to be shipped by diskette or even by modem or Internet from one site to another without risk of tampering or alteration This means it is practically impossible to cheat by supplying contest officials or badge and record issuing authorities with altered bogus flight logs GPS NAV Recorder Sealing The system described in the previous sect
26. ion prevents alteration of a Flight Log from the moment it is transferred to the PC from the Flight Recorder However without further measures it is easy to cause a GPS Flight Recorder to contain a bogus altered Flight Log This could be done by taking the following steps l The pilot flies the task but misses one turnpoint 2 The Flight Log is sent to the PC 3 The Flight Log is modified within the PC to show the pilot actually going around the turnpoint 4 The data file is converted to the standard NMEA 0183 format used for data transmission between the GPS receiver engine and the GPS NAV Recorder memory 5 The modified Flight Log is sent to the GPS NAV Recorder memory using the wires from the GPS receiver engine 6 The modified Flight Log is sent back to the PC The GPS NAV signs the modified Flight Log as it is uploaded to the PC GPS NAV 5 Page 23 2 10 97 The Cambridge GPS NAV prevents this kind of Flight Log alteration by permanently sealing the Recorder box and therefore the critical connection between GPS receiver engine and Flight Recorder memory Removing the Model 10 GPS NAV top cover breaks this seal Removing the Model 20 or 25 GPS NAV main cover also breaks this seal The Waypoint database and Flight Log are lost Replacing the cover does not replace the seal The permanent factory electronic seal can be replaced only by returning the GPS NAV to Cambridge Aero Instruments The sta
27. ition you may wish to review GPS status 5 screens to the left of the Navigate to screen There are at least 24 GPS satellites orbiting 11 000 miles above the earth One orbit takes about 12 hours so satellites are constantly rising and setting like the sun The GPS receiver knows the approximate orbits of all satellites from data sent in each signal Thus when it is turned on the receiver knows approximately where to look for satellites GPS status screens show data from each satellite in the constellation Use the UP and DOWN keys to see data from all visible satellites Number of satellites lt amp Acquired Visible GPS receiver status gt Satellite Pseudo n Random Number PRN Azimuth angle of gt satellite degrees true 3D Fix 6 8 PRN 5 Sig43 lt Signal Strength 33 50 Satellite Elevation degrees lt of satellites acquired Figure 2 A GPS Status Screen As a Satellite gets close to the horizon its signal is more likely to be obstructed by buildings trees and the glider itself Signal strengths should be above 36 for high satellite elevations If they are not check the antenna and its mounting Compare signal strengths using different antenna locations GPS NAV Version5 Page6 2 10 97 Once a GPS fix has been obtained you can see detailed information in the set of screens just to the right of GPS Status Latitude including hemisphere North or South i
28. me of Cambridge as a sample navpoint Name Sugarbush Latitude 44 07 05N Longitude 072 49 61 W Elevation 1470 ft ID 27 Text Runway 4 22 Attributes A Airport F Finish Point H Home Point L Landable Point M Markpoint R Restricted Point S Start Point T Turnpoint W Waypoint A point can have multiple attributes Attributes are displayed in Edit Point screens Only T amp L can be assigned on the GPS NAV Point editing screens By default a Markpoint M changes to W during editing if no other choices are made GPS NAV Version 5 Page 11 2 10 97 Attributes control the organization of navpoints into LCD screen lists Points with T S F or R attributes are listed in rp Alphabet and rp Distance screens Points with A L M and W attributes are listed in the Landpoints screen in order of distance from the present location This means the pilot can mark a potential landing field while flying over it Later it can be selected quickly Attributes also control other behavior For example when the GPS NAV is first turned on the Navigate to screen shows the Home Point H if there is no Home Point the GPS NAV displays the navpoint with the lowest ID Editing a Markpoint changes the attribute from M to W Thanks to Dickie Feakes W points can now be shown together with Task points on the PC display Marked mountain passes and cols are now easy to visualize Remember that the total number of points including Ma
29. n the actual airspace boundaries GPS NAV Version 5 Page 21 2110 97 Recording Flights The GPS NAV is designed so the Flight Recorder may be used by itself without the LCD Navigation display The GPS lamp on the Flight Recorder flashes whenever the receiver is able to find its position Once position is known flight logging is automatic It begins when either horizontal or vertical motion starts Position GPS Altitude Pressure Altitude Estimated Position Error and GPS derived date and time are written periodically into the Flight Log The GPS NAV keeps a buffer of fixes at all times When motion starts two minutes of pre flight fixes are logged This provides a stable barograph baseline for altitude measurement Logging continues for two minutes after motion stops GPS NAV Flight Logs are erased only when new pilot and navpoint data are transferred to it from the PC This means pilots can transfer Flight Logs as often as they please to several different PC s Under new FAI Sporting Code rules Flight Logs made by the GPS NAV can verify FAI badge and record claims They can also be used in glider competition to validate flight paths around turnpoints Pressure altitude as well as GPS altitude and position are recorded Motorglider engine noise is also continuously recorded Therefore Flight Logs from the GPS NAV can replace photographs and barograph traces for both glider and motorglider flight validation Flight Logs also provide useful
30. nected before Battery 1 is disconnected The Model 20 amp 25 GPS NAV s are suppplied with a wall mounted power supply 12 Volts DC 300 mA This unit runs the GPS NAV during transfer of data to or from the PC Note that the outer contact on the power supply connector is Positive See the Specifications section for details and wire color codes for other connections to the GPS NAV GPS NAV 5 Page 27 2 10 97 Troubleshooting The following problem answer P A list may help locate the source of difficulties in installation and use of the GPS NAV P The GPS NAV Model 10 Recorder will not turn on using its own power switch A Its battery is completely discharged or an internal fuse is blown P The GPS NAV Model 10 runs with an external battery but not with its internal battery A The battery fuse is blown This can happen if a high capacity charger has been used if the charging leads have been shorted together or if the charger is of the wrong polarity We strongly recommend use of the charger supplied by Cambridge P The GPS NAV Model 10 turns itself off soon after being turned on A Its internal battery is almost completely discharged The GPS NAV shuts down at 9 5 V P The GPS NAV Recorder cannot be turned on from the display unit A The display cable must go to the GPS Display port on the Recorder The cable may have been connected to the NMEA 0183 port No damage results from this The cable may also be defe
31. ns This is the Elevation screen The Elevation number 1470 comes from the waypoint database created and stored in the the PC Figure 5 Screens for the Active Navpoint GPS NAV Version5 Page 13 2 10 97 Ground Speed Display and Wind Estimation The gliders ground speed displayed with the label V replaces Bearing on the screen where the comment text is displayed The wind component in the direction of flight can be estimated from the difference between indicated airpeed from the mechanical ASI and the ground speed This is only accurate at low altitude because of the difference between indicated and true airspeed If a Cambridge NAV vario glide computer is connected to the GPS NAV true airspeed TAS is computed and subtracted from ground speed The difference is an accurate measure of the wind component in the direction of flight This is displayed on the NAV and used in its final glide computations The ground speed display is especially useful in wave flying If the glider is pointed directly into the wind ground speed may be near zero If ground speed decreases when airspeed is_increased the glider is actually moving backwards over the ground The Track display will also show this GPS NAV Version 5 Page 14 2 10 97 Wind Measurement from Drift while Circling GPS NAV Version 4 introduced a new concept in measurement of Wind If a glider circles without reference to the ground it will drift with the wind The GPS NAV
32. ow much to turn This is much simpler than remembering a compass Bearing setting up a compass Heading and guessing the required Track lt lt i L lt 5 10 15 25 45 5 10 15 25 N N S Z Z Figure 4 The GPS NAV Track Error Indicator When Track Error is less than 5 only the center vertical bar shows For Track Error greater than 45 the center vertical bar goes away followed by the inner segments GPS Track lags behind the actual glider track during circling For this reason the graphic Track Error Indicator is switched off during circling flight GPS NAV Version 5 Page 9 2 10 97 It is important to remember that this indicator shows Track rather than glider Heading This is especially useful during high wind conditions such as flight in wave lift When flying directly into a high wind the glider may be almost stationary over the ground Think how the shadow of the glider moves over the ground A small change in Heading makes a big change in Track Trust the Indicator Navpoint Screens The Cambridge GPS NAV is optimized for competitive and recreational gliding Quick navpoint review is a unique feature of the instrument Most screens to the right of the Navigate to screen are devoted to navpoint review Once the desired navpoint has been found it is always activated by pressing GO It is helpful to experiment with the GPS NAV as you read this section First load enough navpoints to ge
33. rkpoints cannot exceed 250 Only points with Turnpoint T Start S and Finish F attributes are included in the list from which tasks are constructed Even though you can navigate to a Thermal it is not kept in the database and has no ID Markpoints and Thermals show up on navpoint selection lists But they are also easy to find in the screens where they have been marked For example suppose 3 points have been marked The Markpoint screen shows the next point 4 which could be marked Mark Point 4 if the UP key is pressed the screen changes to Select Markpoint 3 Ail the previously marked points may be found this way In this case pressing GO makes Markpoint 3 the active point GPS NAV Version5 Page 12 2 10 97 Supplementary Navigate to screens In the Main Flying Screen more information about the active waypoint can be seen by pressing the UP or DOWN arrow key Runway 4 22 Sugarbush lt lt V 74 135 Trk Dist 35 2 cee Navigate to Sugarbush Dist 35 2 ose Elev 1470 Sugarbush lt s Brg 095 eee Dist 35 2 ese 135 Trk Bearing to a goal is replaced by velocity V over the ground On a Task Track is replaced by Cross Track Error XTE Comments such as Runway 4 22 come from the waypoint database created and stored in the the PC This is the Main Flying Screen It is the starting point for these screens Use the UP and DOWN keys to see the other scree
34. s shown first Use the DOWN key to see Longitude GPS Altitude Pressure Altitude based on standard atmosphere 1013 mBar 29 92 Hg Sound Level Estimated Position Error EPE Date and time UTC Time and date come from the satellites and cannot be edited Pressure Altitude comes from a calibrated altimeter sensor within the GPS recorder It has better short term stability than GPS Altitude and is used for the barograph trace Sound level is measured with a calibrated microphone and recorded as part of the Flight Log The recorded sound level shows when a motorglider engine is running The Cambridge GPS NAV is optimized for use in a glider moving towards a waypoint Those conditions must be simulated to fully understand the Navigate to screen This is where the walking comes in To keep things simple you will mark your present position as a thermal walk some distance away and navigate back to this position Here is the sequence a Return to the Navigate to screen by pressing GO 2 Move one screen left to the Mark Thermal screen 3 Press GO to Mark your present position as a Thermal The next step is to actually navigate to this marked Thermal 4 Move to the Mark Thermal screen again 5 Press the UP or DOWN key You will see Select Last Thermal 6 Press GO again Thermal becomes the active navpoint Navigate to Thermal 7 Walk away to a distance of at least 500 feet Turn around and let
35. s soon as power is applied The GPS NAV display ON switch is not used You must use this connection if the GPS NAV is to be used without its LCD display and without connection to a Cambridge L NAV Switched power using the Green wire means the Model 20 25 GPS NAV responds to the ON switch Power may also be slaved to a Cambridge L NAV When the L NAV is turned on the GPS NAV turns on automatically When the L NAV is turned off the GPS NAV waits 30 seconds and then turns itself off Wire color Yellow Green Red Black Port Name Pin 1 Pin 2 Pin 3 Pin 4 12 14 Volt ee eee Switched Power Model 10 12 Volt Ground 12 14 Volt Power Switched Un switched Power Model 20125 Ground 12 Volt 12 Volt Ground Power Cable ae GPS NAV Orientation Black wire this side Barrel connector 12 VDC Un switched Outside Positive GPS NAV 5 Page 36 2 10 97 Datacam Cable Wiring The 6 wire Datacom cable carries NMEA 0183 data from the GPS NAV to other devices These signals are used by a Cambridge L NAV or S NAV They can also be used to provide input to other devices The GPS NAV outputs NMEA sentences GPRMB and GPRMC It also outputs a proprietary sentence which gives the elevation and attributes of the active waypoint Further details of this sentence may be obtained from Cambridge Pin 1 the power control switch input enables a remote device to turn the GPS NAV on and off When this input is 5 Volts the GPS NAV will turn on W
36. t the idea See the section labelled Waypoint Editing for details Better yet load a navpoint database from the PC software library Finding and activating navpoints is the same for all screens Note Refer to the Primary Screen Map on Page 2 to see how navpoints are organized into columns of screens 1 Choose the optimum navpoint selection screen for your neds using the LEFT or RIGHT arrow keys 2 Use the UP or DOWN arrow keys to find a navpoint 3 To make this the active navpoint press GO 4 To keep the existing active navpoint return to the Main Flying Screen using the LEFT or RIGHT arrow key GPS NAV Version 5 Page 10 2 10 97 The Last Point screen The GPS NAV lets the pilot switch easily between two waypoints of interest Here is how it works with navpoints named PARIS and MOSCOW The pilot is navigating to PARIS but is interested in MOSCOW MOSCOW is selected from any waypoint list and GO is pressed Now MOSCOW is active and is shown in the Navigate to screen PARIS is now stored in the Last Point screen just to the right of the Navigate to screen The pilot can re activate PARIS from there by pressing GO When PARIS is re activated MOSCOW replaces PARIS as the Last Point It is quick and easy to re select MOSCOW if desired But it may take a long time to fly there More about Navpoints The GPS NAV can store up to 250 navpoints Here is the data for each navpoint using Sugarbush ho
37. tus of the GPS NAV Recorder seal is shown at power on See the following section for details of the power on message sequence When a GPS NAV cover has been removed the message GPS Recorder is replaced by GPS Recorder Sealed Not Sealed The GPS NAV will still function However Flight Logs will not be secure and will fail the electronic Validation test This means that an Official Observer will be required to verify independently that the flight recording has not been altered Power on Messages A series of messages is shown when the GPS NAV is first turned on They show revision levels of Recorder and LCD display firmware Pilot s name glider identifier Recorder serial number Recorder seal status and battery status Some messages are also shown whenever the ON key is pressed Pressing GO stops the display of messages Recorder serial number and factory security code are assigned by the manufacturer They cannot be altered The pilot s name and glider identifier are supplied by the pilot using the PC See the PC Software User s Guide for details GPS NAV 5 Page 24 2 10 97 GPS NAV Model 10 Battery Status and Battery Charging The Model 10 GPS NAV has a self contained 12 volt 2 0 Amp Hour Gel Cell Lead Acid battery The Model 10 GPS NAV draws about 220mA A fully charged battery reads above 12 7 volts Normally this will power the Recorder for more than 8 hours An old battery or cold weather will reduce this time When the
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