Home

GRAPHICAL MAGNETOMETER Operating Instructions

Contents

1. RERI QUO NOLO OLOR NOLO NON NOI NO 066556666050 1 Highlight the option that reads DATA LOGGER OFF 2 Press ENT 3 The option should now read DATA LOGGING ON had a total of 119 read origina 11 3 START DATA LOGGING All measurements will now be logged to a data set held in the system RAM battery backed The data on the prev MEMORY r 2 gt D un D D D 2 T Q ci lt 31 the usual In Isplayed that reads DATA LOGGER 101 ill now read DATA LOGGER OFF ht the opt ion W 18 ighl Press ENT H The opt the 1 key to start and 2 to stop data logging status is d 1 2 3 pressing 11 5 START STOP QUICK KEY LOGGING 11 4 STOP DATA LOGGING Data logging can be more readily stopped amp restarted during magnetometer operation by manner Aquascan International Limited r 2 gt D un D D D 2 E Q ci lt 12 0 DEPTH MONITOR SETTINGS J 0 Z JE A Ce 200200 eL USE ARROWS amp ENT TO SELECT DONE N WHEN ET Ju COP 1S 15 The above menu selection allows for the units displayed to be selected as feet
2. 3 255 8 e 5555 555556 SOOO 8 8 DATA RECORDO O1 gt gt 88 T 8 52 060009 T 5 8 2 00204040404 55 052526526069 555555554 929 9 9 9 4 SS 50 SS 555 gt F eyes lt 2505255 gt gt 8 xX BWw 550555650555 5 oS BBW88 606006000 555695556059 52 8 7 d 3 8 9 4 2 s eS gt lt gt 2 z7 5 SS gt 22 ars TEs A 5 lt B wee 5224 Kd Sues bod 2524 224 ESF PSSA XS 22424 190949 1252504 95264 1252504 95264 1252524 ws 25594 0045 904 90006 904 55 50 M 8 OSM b 59 957070747970707076707670707074 0454 070707070749707074707074707070707070747907070707074787074767070747076747074700707470707070707670707074707074707970747070349 CCCs 95 555 596 5965 505 OX 565055 9595
3. 22 292 C L 595550 BW 2 8 7 55 5 2 oo 15 CSS SNE x 55 hows the LS 5 OO F CO 3 555 ENT SELECT o d lt lt COL 1554 KON M FISH 4 5 5 gt 29 OE cS 2 8 8 o er 500 5559 KKK 5 xX 8 Wo x Palas WWE 5555 552 SRR 24224 5554 22224 5554 22224 2 EEEE EEEE ETETA 970 47470747070747070707470707 7070747470 97470707474707074707070747407074707070747070 974970747470 9707670767470707070 49 555 5 5 0 0C OC 55 555955555955 55 5 555555 5555 9 06 20000000060 EE 9 92 C ID 2 RA RD 2 2 2 23 2 2 2 2 E 22 eee eee E E I I RA B amp W SOOO diagram s SE LUND t the magnetometer operating parameters select the MAGNETOMETER SETUP X1 OOO MAGNETIC ZONE XxI 00L OPTIONS THEN MENU WHEN DONE POLARISATION TIME FISH OFFSET USE ARROWS 8 ica djus 19 r D un D D D 2 E Q ci lt Press PWR keypad and hold unt ble bleep CAUTION DO NOT
4. XXX KX 8 8 Men 22 9 01 XXXI 5551 OO XXX M 8 KX DXX 8 224 8 22 9 8 XXXI 5 5 8 5551 OO 15551 0 8 5 8 9 x59 8 24 8 Aquascan International Limited ts NMEA interface port 14 1 es relative amount of used placed next to the histogram and DONE this is to the right hand side of the 8 AS 8 Doo 8 po 8 8 A M Dow 8 8 XXX XX Doo po 8 MAS e 8 e Doo 8 T At po 8 MM Te Ten ee 8 Do 8 XX Doo W XXX po po 8 ee 8 Doo ee 8 AM XX XXX TA W MM 8 M Doo aee poo AM 8 ee XX poo IA M Doo Me poo 8 Do XX poo IA
5. T T Dod 8 8 ee T 5 5 Pod 5 8 8 9 5 T XxX 5 e 8 5 eee 88 Mes 5 AM ee 8 XXX 8 XXX 8 MM 8 88 222 0 9 96 0 0 6 06 04 6 0 06 60 0 40641601001 119 6 946 00 6 060 6 6 66106606666 9 9 95 63 69 9 5 MAR NON HH UR RON SR IR RORIS UR SURROUND SUR IRA ORAS RS 552 8 te Aquascan International Limited 5 8 e 8 52 oe L 25 5 9 5505 00000 W 8 5 5 2 te 88 gt 8 8 8 e 2 o 5 555 LOO 5 2 8 en 8 0505 250 52 8 52 52
6. lt gt RS 55 22 5252 2265 555 25252 2 8 ther a printer or a 55 8 5 5 5 5 5 gt at 5 8 e o Se 5 e 25550556 SSS 3 205 55 5 d 8 2244 00200 a h 5 8 d SS 5 lt gt lt 5 8 lt 9 8 22 IN 8 gt 8 5 25 o ROK SES 5 gt 555 55599 55 lt gt 5 552 090905 2 gt lt gt lt DATA TRNG 8 e XS x 5 2 2 5 d d gt x 8 59 OOOO 5555209 gt x 8 55 e 5 SEES 5 SOX COSS XO 8 O 95 5 L J ARROWS 5 gt Se 5 2 8 5
7. 2 5 40 System for European operation with Solenoid sensor and 40m cable AX2ET 60 System for equatorial operation with Toroid sensor plus 60m cable AX2DES 50 System for European operation with Solenoid sensor plus 60m cable and depth of tow fish sensor AX2DET 50 System for European operation with Solenoid sensor plus 60m cable and depth of tow fish sensor AX2PED 150 Professional version for Worldwide operation supplied with integrated depth sensing tow fish pre amplification amp a Solenoid sensor complete with 150m cable and a elobal tuning capability 1 1 PACKING LIST CHECK A loose sheet packing list will be found at the front of this manual representing a comprehensive inventory of individual items that have been included this sheet should be used as a checklist Any queries resulting from this initial check should be raised with your dealer or directly with AQUASCAN NB we suggest you keep the Freighting case and packing material as a precaution for returning the instrument should this be necessary for upgrade or service at a future date 2 0 SYSTEM INSTALLATION 2 11 MOUNTING The AX2000 display unit is supplied with a conventional gimbal mount bracket allowing the unit to be mounted on horizontal vertical or sloping surfaces The degree of weatherproofing and the watertight nature of the connections make the unit suitable for mounting in exposed positions however it is recommended that where possibl
8. e lt lt d 25 555505 25 EX 5554 5 B ROS B sete 2224 2224 5 8 B 8 B RORY KSSS ROR B 224 B ae 55954 B 554 8 gt 252 lt 2522 5 5 8 25 55 2 525 x 5 5555 e 8 zm 52 5 8 52 5505 22 xS 5505 2 s 55 52 555 8 00 5555 5 8 iet 55 8 2 os de 555 22224 SESS 552 8 525 559 lt lt lt e 8 T 222 3 2 8 252 69250 55555 50550 55 55 2 55 255 gt 8 oS t lt lt lt 8 2579 2 5 lt F bic law response for most magnetic 5 x 555 555 22 B 550 55525 for any part 5 55 x 55 55 e 8 252 8 5 8 2 250 t 2 5555505 550 55 25 DATA STRING 55 8 2 lt 2 8
9. 2 5 POWER SUPPLIES The 24v power supply is one of the most fundamental aspects to get right for optimum system performance The combination of extremely high sensitivity together with the very low operating frequency make the magnetometer instrument very vulnerable to interference via the power supply cables The ideal power source for the AX2000 magnetometer 1s a totally isolated amp independent battery isolation eliminates both noise from a ships charging generator the major source of interference and the superimposed noise from other instrumentation The 24v Battery supply The ideal 24v power source is a pair of 12v 60AH or larger lead acid batteries in good operational condition this should allow an operational period in excess of 24 hours before it becomes essential to recharge NB Even in situations where a dual battery system is available allowing one battery system to be isolated from the charging system both ve and ve leads have to be fully isolated from the boat system to ensure interference free operation of the magnetometer To evaluate the feasibility of using a boats un isolated main battery system a test facility is outlined in the SETTING UP PROCEDURE section this gives a means of testing the complete installation for interference 2 4 TOWFISH INSTALLATION Although the magnetometer sensor is a towed unit tow fish the inboard section of cable has to be routed to the display unit The main considera
10. 8 25 5 25 25 5505 8 Z eS Inverse 8 2525 55 555 525 52 8 8 ing lt 2 gt 3 552 25 8 25 25 8 et 2 F 5 22 x 25 555 55 505 555 lt 5 8 lt lt lt F e 55 F MEN WHEN 5 5 SS z5 555 Se T CGA RME RM ES 55 525 8 525 eet lt lt 505 5 2 505 55 lt F T 8 gt a SS 2s 9 3 lt 8 2 5 lt 2s 25 2 SS 8 55 c 55 8 5 8 COMS FRIN O1 gt Ol S NONE C mirrors T 55 lt gt 2 gt 8 o 2 15 Way crucia E 25 25 55 le 8 222 tes 25 Z e 755 8 de oS t B 222222 5 8 x 8 8 gt x 8 2 8 0 B OSS 3 lt OO 55 2222 55 525 mic sca 55 55 8
11. 8 5 2525 2505 2 a th IONS 55 lt gt 8 m 5 8 lt gt 2 x 2 8 55 8 lt ful terms says that a change of proximity to an anomaly by a factor 22 5 55 x 9900 y Q 4 N 2 Ws DES NMEA ari f anomaly amplitude that can be accommodated with L J ARROWS lt lt lay the survey results us f the initial small changes that occur whilst accommodat large overall response without resorting to scale changes maximum reso The sounder can be set ON or OFF from this sub menu muting the audio alarm threshold 7 73 SCALE This could also be termed range selection as the scaling factor multiplier chosen sets the however where a large anomaly response 15 anticipated the use of LOG scale will allow The logarithmic mode has been designed to operate with a base 8 giving scale increments of 8 the 64 512 etc The choice of a base 8 anomalies th Return to MAGNETOMETER MODE sub menu by holding down the MEN button of 2 will produce a corresponding magnetic change by a factor of eight The choice of LOG or LIN scale 8 0 COMMS AND NMEA SETTINGS d 52 9 ES ES PS 5954 pd Ne Me 554 555504 M 2224 S 229 a Cu 2 2 4 c3 Q O ASAS ZZ m un 3 N c BBBB x v SES 5 t g
12. e 5 7 17 18888 s m MM dU PUR E Lot o LM RS 222 Leal pes TEL BERE ERR EHI HERE 2 Th hinh a ap HAN a T 2 0 1 1 t i iim TET ue pe MG Es ERI 88 UT HIR PALE ORTUS E ommo er LUND dal UTICA Muse Wi bert u TLL di e 44444449 t T Sage ERRES Hi tt setae badd 1 me eu RETI FERRES ED srr rE kE3 10 000 STRENGTH E nanotesla 100 r 2 gt D un D D D 2 T Q ci lt 15 DISTANCE SB 9006 600000660600 EXXX YKY 8 0 Aquascan International Limited CMM QS KKK PVM MMM IMM MIM MEI IO IIIA ee NNR NNN IS NNN amp QS 000 lower half of the scree
13. 8 25 5 5 t 25 ee ll then be disconnected 25 5 5 8 5 2 6999090909000 2 e 5 555505665660 25 255555 0 04 SOR xX 8 5 25 8 55 gt Se gt 5 8 5 5 8 7 259 5 5 5 8 8 T 2 5 8 552 5 55 eX 8 5 5 8 60 9 4 2 ex 2 8 the SETUP MENU however the DONE 8 lt lt 8 8 oo 8 674221966 59 X 55 8 8 F OLD ZONE 25 55524 88 heard power w 7 8 e 5 0 2 e 18 F SS 5 5 ste 8 552 8 gt 25 8 5
14. 8 6 B 55505606 550 B TER 8 B B B amp amp BW SERS 0x 50 W 8 Tere Ota 0 T0 SSSI 07000707070 0707474702070 070102420 01010 0 0 010 0 0 820101019202910 04020 0 9 0 040 0 9 0452 5102095420504 949 9 105 10 9 9 5 10 49 00 055 0 0 10 5 0 0 5 9 4 0 9 4 0 0 9 0 4 9 4 0 4 9 4 7 50555555 8 3 45 5 5 555555559059 5 lt 555555555555555555555555555555555555555555555555225555555555555555555 2 4 4 4 5 255 52 5555555 8 MA 555 W x RY 8 m x ste B amp 22 8 W 2 55 27 B8 W lt gt tet e OO et XO 0 9090909 572 50 8 2 55 B x 8 55555 88 W 8 55 p D CODO aee OO O0 0000060006 00 960096000 000 0000 06000 00 0 0 9 000000 0 9090 00 009 0 000 09 0 00090 90 06009 9 00 9 0 900 900 90 9 9 0 0 9 9 0 90 900 9090 9 0 900 ORE TOT EISE ODORS A 5 RRR 0000500000000 0 0050 9 0 09 0
15. 8 MMC M Me XX Doo XXX 8 Me 8 XX 8 MM pond Me XX Doo 8 po 8 Doo 2 ion indicat gt lt gt lt OO X1 OO MEN WHEN The black port layed isp ARROWS d IONS ues AU IA I 555555555500 8 ASSI EAR NN ERN NIA VR INS NANI 2002229 7 4992002 KKK KKK RAKE KKK has been selected then the word LOG 15 ing NB For more information see the section COMMS and NMEA SETTINGS refer to the NMEA appendixes for detailed interface information If data logging has not been selected then the words NOT LOGGING are displayed in the histogram the analogue histogram The analogue display takes the form of a vertical histogram in which the lower part of the black section indicates the depth The current tow fish depth 1s displayed both analogue form and as a digital value beneath display The h
16. RMC sentences these include position data with minutes to 3 decimal places which in effect gives a position resolution to 1 1000 part of a minute of position To optimise the choice of sentence utilised it is necessary to refer to the operators manual for the particular navigation unit being employed this may give a comprehensive NMEA structure listing enabling the operator to select GGA or RMC in preference to GLL alternatively by referring to the relevant appendix at the rear of this manual the correct option may be identified However if it is still not clear which interface sentences are transmitted by your navigator it is possible to test each option in turn and confirm if the navigator position is repeated at the lower part of the screen whilst in magnetometer display mode NB THE POSITION READINGS ARE NOT DISPLAYED UNLESS THE MAGNETOMETER IS FULLY OPERATIONAL AND UPDATING EACH TIME THE MAGNETOMETER TAKES A NEW MEASUREMENT THE LAT LON POSITION DISPLAY IS UPDATED The appropriate interface baud rate 19 set automatically when 0182 or 0183 19 selected The transmit baud rate 1s always the same as the NMEA input baud rate The COMMS amp NMEA SETTING menu shown indicates the current transmit Tx status as follows B 4800 BAUD RATE D 8 NUMBER OF DATA BITS P N NO PARITY S 1 1 STOP BIT 28 AX2000 Graphical Magnetometer User Manual 10 0 DATA OUTPUT 10 1 STYLE The 2000 can reproduce the surv
17. To establish the relevant magnetic zone for your area of operation refer to the total 1ntensity maps in the appendices Referring to the example below the major contours refer to lines of constant magnetic intensity x 1000 nT gammas It can be seen for instance that the UK 15 roughly between 47 to 50 000 nT which 15 easily accommodated by the 43 52 44 51 actual ZONE selection 20 AX2000 Graphical Magnetometer User Manual To set the appropriate magnetic zone 1 Highlight the required option 2 Press ENT to select option CAUTION The magnetic zone will not normally require to be reset unless the magnetometer is being re located to an area with ambient field strength outside the MAGNETIC ZONE value indicated NB In case of accidental memory loss or reset the standard default setting of 43 to 52 44 51 will be selected automatically on power up this a standard setting for parts of the world including Northern Europe part of North America and Northern Australia 21 AX2000 Graphical Magnetometer User Manual 7 31 Aquascan International Limited AX2000 IPA 3 FITTING In order to change the area tuning zone of operation pre tuned IPA 3 circuits are available and require to be substituted as follows l 6 Undo the 4 screws on the rear of the case to separate the two halves and expose the AX2000 circuit Remove the 3 screws retaining the metal screen at the top left above Carefully pris
18. mane C LU WU X SET B E E 2211 11 3 Uu 9 Ga AUN s a gt ANT 6J 1993 codd COMMS NO ISOLATION 1 The arrows above show the position of the RAM chips in an AX2000 PCB Make sure all power 15 disconnected from your AX2000 display unit If there 1s already a RAM chip installed gently prise the existing chip from the DIL Socket using a flat blade screw driver or similar tool Note Make sure the chip is lifted up level at all times as lifting it up at an angle will cause pins to bend and this can severely damage the chip 3 4 Once you have removed the old RAM chip gently slot the new chip into position Make sure all of the chip pins are lining up with the DIL socket pins and ensure the chip 15 orientated correctly The AX2000 Display should now be ready for testing out the new RAM 45 AX2000 Graphical Magnetometer User Manual APPENDIX III AX2000 DATA FORMAT The following format 1s output by the AX2000 family of magnetometers at 4800 baud via an opto isolated RS232 port Tow depth Header Mag lat lon Depth DBT SAXMGD 00010 5135 106 N 00259 698 W 0 0 14 0 SAXMGD 00010 5135 116 N 00259 698 W 0 0 14 96 SAXMGD 00010 95135 129 N 00259 0790 W 020 142 9 The last two fields are only available the AX2000DES DET amp AX2000PES PET versions these include the towfish
19. AK ARK K RAKE RRA K RAKE 555555556556 55650 8 8 Aue Dx 8 5 8 Po 5 Pd 5 N d Po 8 8 W Dd e 4 Pd 8 dem 5 d 55509 8 8 Po Pod Dod Ae 5 8 e 5 8 Po 9 Me e 59 8 4 9 2224 8 8 555 Dd 5 5 Mes 9 5 5 XxX Ms 8 8 Pd W ee
20. D 2 O o lt N e gt Q 23 Ke 956669656666 IIIA O 45 RRR IIE NSN SIRINI NO 2 E MAII IIIA M Lr 5 2 N N IIIA N wi RRR RK RK IG L 2 KKK KKH Y Z c SSSI 3 DIOR RRR RG N O en O Un KKK 90905996905 909090 90905090 909090 90909 90 IKK UO KKK KKK KEK KOK KKK KKH KG O d XXXII gt RRA RRR AINSI SANITARIA ASISTIR K 2 Z Z c e lt ci rA Q A O E cu 5 2 s gt do 2 E an d gt a N O we lt 2 e ur 1 6 tely 16 1001 15 ima each pos tes to 8 x 32 f approx tted is equa 1 f guration 15 In the case of the AX2000 PES amp PET th ing storage time o 1 and allows a data logg ility b imum capa lent to 32Kbyte lay confirms the extended 256Kbyte RAM conf the max IS 1S th occupied and is equ IOhrs duration The above disp 256Kbyte AX2000 Graphical Magnetometer User Manual 5 3 MAIN M
21. FIT TO DATA When downloading information graphically the AX2000 now prompts the user to enter a choice of scale to print the data DOWN LOA Pressing the ENT key Instructs the 2000 to automatically select the best fit scale for the data to be printed on The AX2000 achieves this by searching through the file to be printed for the largest deviation If possible the scale selected will allow this maximum deviation to be printed 1 5 Pressing any of the numbers between 1 and 5 will select the scale opposite that number this function allows the operator to examine the smaller detail sometimes lost when the same data 1s printed out on a larger scale 13 6 EXPORT DATA To EXPORT the data set 1 Highlight EXPORT 2 Press ENT The AX2000 responds by exporting the relevant data set in the format defined by the previous stages 13 7 CLR To halt transmission at any point hold down the CLR button 13 8 CLR SET To ERASE any particular data set from memory 1 Select the data set to ERASE 2 Highlight CLEAR SET 3 Press ENT 34 AX2000 Graphical Magnetometer User Manual 13 9 CLEAR ALL To ERASE ALL of the logged data from memory 1 Highlight CLEAR ALL 2 Press ENT WARNING ONCE THE MEMORY HAS BEEN CLEARED A CLEAR ALL FUNCTION THERE IS NO WAY OF RETRIEVING THE DATA THAT HAD BEEN PREVIOUSLY LOGGED NOTE The data set numbers do not re
22. NA ESRB A ARR E ERES ate tat tta teta att RR CR RR r 2 gt D un D D D 2 T Q ci lt If the contrast needs opt 5 41 CONTRAST The current contrast sett screen To adjust the contrast 1 Highlight the histogram 2 Press the left right cursor keys to increase decrease the contrast until an opt achieved ighlight the required option 2 Press the ENT KEY to select option by the following procedure 1 Highlight the relevant option 2 Press ENT to select option 3 Return to main menu DOWN 0 POWER CAUTION DO NOT SWITCH OFF THE BACKLIGHT IN LOW AMBIENT LIGHT CONDITIONS AS INSUFFICIENT CONTRAST MAY MAKE ANY FURTHER MENU SELECTION VERY DIFFICULT The screen background can be made predo To switch the back light on off conditions 5 42 BACKLIGHT 5 43 BACKGROUND 6 IESE IEI AEN 00 amp VV 0509099 5 lt x B B 8 OS o 8 535 5 5 3 7 x lt 8 8 e 8 Aquascan International Limited 535 e 8 50 eX 505 e 52 NEW ZONE 0000000000000 eX 505 e 8 00050000600 000000060006 535
23. RK 0 0 90 0 0 5 SRR 000 0050000 000 900 00 9 0 9 0 9 0060 0 00 09 00 999 00 0 0 09 000 0 BORON K RK RRR 0 0 0 0 0 9 0 00 0 0 00 9 9 0 SRS ORO O0 d 000000 909 0009000 9 90009 9000 9 959 0 909 9 999 0 0 6 9 0 9 9 9 0 9 9 4 9 9 0 9 9 9 0 09 9 0 99 0 0009 909 00 9 0 9999 99909 90 9 909 9 000 9999 ROO OOo 0 000009 0600 009 90099696 00 969990 5 90 0 09 90 9 999 0 0 9 009 9 9 9 0 9 9 4 9 0 9 99 9 9 9 55555 555555 556 665555655665555565555555555 56 5 5555065555556 555555555555555 ORoQ AIL lt lt ORO RERO XII ROO OE 8 lt lt The main menu presents 5 options 1 MAGNETOMETER MODE 2 MAGNETOMETER SET UP 3 TUNE MAGNETOMETER 4 DOWN LOAD DATA 5 TERMINAL SET UP 5 31 SELECTING A MAIN MENU OPTION To select an option use the UP DOWN keys to move the cursor reverse video highlight to the required option Once highlighted pressing the ENT key can choose the option 5 32 SELECTING A SUBMENU OPTION Once an option has been selected from the main menu the AX2000 will provide the appropriate sub menu To select an option any sub menu the CURSOR KEYS are used to move the highlight box around the screen Once the required option 1s highlighted by the box press the ENT KEY The selection 15 confirmed by the relevant option being displayed in reverse video THE AX2000 WILL UPDATE Its CONFIGURATION TO THAT INDICATED BY THE REVERSE VIDEO ON RETURN TO THE MAIN MENU OTE The only exception to the abov
24. TUNING THE MAGNETOMETER 7 6 MAGNETOMETER MODE 7 61 MAGNETOMETER DISPLAY 7 62 ALARM LEVEL DISPLAY 7 63 POSITION DISPLAY 7 64 MEMORY HISTOGRAM DISPLAY dal MAGNETOMETER SETTINGS 7 71 ALARM nT 1 12 SOUNDER AUDIBLE ALARM 7 13 SCALE 8 0 COMMS amp NMEA SETTINGS 8 1 TX TO 8 2 COMS AX2000 Graphical Magnetometer User Manual Aquascan International Limited 9 0 NMEA INTERFACING 10 0 DATA OUTPUT 10 1 STYLE 11 0 DATALOGGING 11 1 DATALOGGING ON OFF 11 2 DATA SETS 11 3 START DATALOGGING 11 4 STOP DATALOGGING 11 5 START STOP QUICK KEY LOGGING 12 0 DEPTH MONITORING SETTINGS 13 0 DOWN LOAD DATA 13 1 SPEED BAUD RATE 13 2 SEND TO 13 3 STYLE DATA 13 4 DATA SET 13 5 BEST FIT TO DATA 13 6 EXPORT DATA 13 7 CLR HALT TRANSMISSION 13 8 CLR SET ERASE DATASET 13 9 CLEAR ALL ERASE ALL LOGGED FILES 14 0 CONDUCTING SEARCH 14 1 DEPLOYING THE TOWFISH 14 2 SEARCH METHODS amp CONSIDERATIONS 14 3 CALCULATIONS 15 0 SEARCH PATTERNS 15 1 LANE SEARCHING 15 2 DRIFT SEARCHING APPENDIXES L AX2000 TROUBLESHOOTING GUIDE II AX2000 RAM INSTALLATION III AX2000 DATA OUTPUT IV AX2000 WORLD IPA 3 MODULE ZONES V SERVICING PHONO CONNECTORS MANUFACTURER CONTACT INFORMATION VII PRODUCT BROCHURE SPECIFICATION AX2000 Graphical Magnetometer User Manual INTRODUCTION The AX2000 GRAPHICAL MAGNETOMETER series is the result of natural progression in development and has set a new standard in the 1990s and into the 2000s for a
25. complete a long circular course without any significant change in the steady state reading of the magnetometer 2 The potential hazards of snagging the tow fish 4 3 lt The anticipated minimum depth of water including any potential hazards that could allow the tow fish to snag has to be taken account of The tow fish has a natural tendency to sink particularly at low speeds and related to the amount of cable deployed To eliminate the possibility of snagging particularly in depths of water less than 10m 30ft a tail float on a light line of a suitable length will act as a drogue and should the boat become stationary will support the weight of the tow fish The ideal float 1s a slim line fender with the ease of attachment through the eyelets and it s reasonable ability to towed through the water 3 The nature and mass of the object to be detected The relative depth of the tow fish in the water has to be considered in relation to the size of the object to be detected Fig gives the maximum distance at which various tonnage s can be detected this has to be related to the depth of water in which the search has to be carried out Where the target 15 estimated to give a sensing distance which 15 large in relation to the depth of water the depth at which the probe 15 deployed 15 relatively unimportant however where the detection distance 1s close to or greater than the depth of water the probe needs to be deployed as deep as po
26. computer allowing the memory to be cleared for re use without loss of valuable data PC support software options are available to allow both real time PC viewing storing and subsequent PC analysis of stored data this can provide a very powerful aid for survey Real time display and direct data logging of measurements on a PC can greatly enhance a survey The application of the PC for the processing of magnetometer data can virtually bring order to chaos an apparent meaningless set of magnetic deviations can be processed and represented as a series of contours giving a clear picture for interpretation The current high resolution colour screens VGA SVGA used on PCs allow a further dimension to the display of processed data Progressive changes in the measured values of the magnetic field can be attributed a range of colours from the spectrum available alternatively successive surveys can be overlaid on the same screen with a clear separation Hence with the AX2000 series a foundation has been laid to provide the basis for progressive inclusion of further innovations that will ultimately take the instrument far beyond the basic functional role of a proton magnetometer AX2000 Graphical Magnetometer User Manual 1 0 SYSTEM CODING A simplified coding system has been adopted to cover a range of options available with the AX2000 series the letters and numbers following AX2 determine the status type of sensor and length of cable supplied
27. depth monitoring facility the last data field 1s provided by a combined source that provides depth SDDBT in addition to a standard positional sentence Alternatively a special combining circuit can be supplied by AQUASCAN that will pre combine the data strings from a GPS amp sounder that have the relevent NMEA data strings available 46 AX2000 Graphical Magnetometer User Manual APPENDIX IV WORLD IPA 3 MODULE ZONES There are five standard types of IPA 3 Module which enable optimum operation of your AX2000 in all magnetic zones of the world Below 15 a list of options available MODULE STEPS FROM TO T A 5nf 64 074 52 048 2728 2216 T B 6181 52 215 43 029 2225 1832 6181 43 452 37 815 1851 1610 T D IOnf 38 707 32 765 1648 1395 I5nf 33 000 27 480 1405 1170 For more specific requirements please contact your nearest service agent the support department at Aquascan International Ltd 47 AX2000 Graphical Magnetometer User Manual APPENDIX V SERVICING PHONO CONNECTORS REAR OF CASE Buccaneer Waterproof Connector Phono Chassis Socket NB Connector cap reverses to act as a removal tool ui Core 1 Rear Nut 2 Sealing Washer 3 Chassis Body 4 Phono Socket insert 5 Insert retaining ring TOWFISH CABLE Buccaneer Waterproof Connector Flex Plug FMP Inner amp Outer screen boc Bose D amp D Anti phonic semi condu
28. direction of the contour lines can give a very flat base line and hence maximum ability to note changes due to man made anomalies 7 The size and type of vessel deployed for the search The larger the survey vessel the less the manoeuvrability which 1s fine for the survey of a large area where each lane 15 of substantial length but 1s not necessarily an asset for the search exercise in small confined areas another disadvantage of large vessels 15 the fact that a long cable length has to be deployed giving an appreciable difference between boat position and actual tow fish position 8 The total size of area required to be surveyed Assuming that sufficient is known about the target in terms of tonnage and dimensions a plan of action can be determined to cover the search area in such a way that a The survey 19 fully data logged to allow an accurate assessment both during and subsequent to the search b The survey 15 carried out to a standard guaranteeing that should the target not be located within the prescribed area then the ground covered can confidently be eliminated from any future search activity 38 AX2000 Graphical Magnetometer User Manual Aquascan International Limited 14 3 CALCULATIONS By reference to the sensing distance graph it 1s possible to determine 1 The maximum distance at which a given target can be detected from the surface 2 The degree of magnetic change that can be anticipated when si
29. magnetic field this diagram clearly shows the convergence of the lines through the ferrous object The size of the object in relation to the earth s field 1s deliberately exaggerated to illustrate the effect The effect shown is the induced field which is due to the much higher permeability of the ferrous object to the surrounding matter 11 AX2000 Graphical Magnetometer User Manual Aquascan International Limited THE MAGNETIC ANOMALY OF A FERROUS OBJECT IN A UNIFORM MAGNETIC FIELD Apart from objects of a ferrous nature all other matter can be considered to have a permeability of near to unity this in effect means that no other matter has an appreciable impact on the presence of the earth s field and hence has no magnetic detect ability The value of permeability of a given object Is one of the major factors determining the amount of induced field and hence the detect ability distances Permeability variations of many orders of magnitude are apparent in the many grades of ferrous material such as wrought iron cast iron steel etc Hence the detection range of various objects of a given mass depends upon the composition THE MAGNETIC INFLUENCE OF A WRECK CAN BE DETECTED AT DISTANCES EXCEEDING 400M 12 AX2000 Graphical Magnetometer User Manual Aquascan International Limited PLOT OF MAGNETIC FELD STRENGTH AGAINST DISTANCE FROM THE WRECK REFERENCE LEVEL The above plot is a representation of
30. or metres th effected by highlighting the required range the relevant units and pressing the ENT key followed by the MEN key to return to the MAGNETOMETER MODE MENU 13 0 DOWN LOADING DATA a ANASTASIA NU KERN KKK KRENEK SSRS 656565665566 656565666565 RSRSRS 88 ps 625504 25254 500 4 1252504 eee 2224 POO 5594 PSSA Sa B DOG XS te 2224 Pod 95254 5252594 5554 224 Xd 2224 Met 2224 yee Xd 2224 26244 2224 244 2224 50 0 1252504 5254 2224 yee 25254 05254 CQ PSSA 5554 24224 055054 22224 8 5 5 5 5 5 5 5 5 552 8 XS 5 gt o Pe 52 gt x 2 5 gt x 5 8 255 52 24 xX Pe 3 5 5 8 5 5 gt gt 2 5 x 8 590 8 BON 8 5 2 57 2 es te 5 5 55 5 5 ox 5 5 5 5 55 5 gt 5 5 2 5 gt 2 52 te 5 o
31. quoted as a fraction or a ratio will obviously relate to the total intensity for the part of the world where the magnetometer is employed An accepted level of change that is the smallest change attributable as a positive indication of an anomaly is 5nT Fundamentally important to maximise sensitivity 1s to achieve a stable base line from which to analyse changes if the base line changes outside detection range of any anomalies can be maintained within 2 to 3nT this relates to a well optimised magnetometer installation 4 5 SENSITIVITY GRAPH Having established the resolution and detection criteria for the magnetometer the potential detection distance can be assessed for any given size of ferrous object within a reasonable predictability This is compiled as a graph of field strength deviation against distance This graph is very important to the magnetometer operator and can provide the information base necessary for the planning required to guarantee a successful search operation If we analyse the graph whilst taking account of the above criterion we can establish the following useful factors 1 The maximum detection distance for any given ferrous mass by determining the intersection of the horizontal distance line to the 5nT point of the tonnage line 2 The relationship between increased tonnage and distance is roughly based on a 2 times increase in detection distance for a 10 times increase in ferrous tonnage 3 The change in deviati
32. seawater A piece of stainless steel or bronze inserted into the water and coupled to the battery with a copper or stainless wire will suffice the metal contact can be hull mounted or can even be loosely coupled to the towfish cable behind the vessel B Electrical noise coupled into the cable The Towfish cable routing can be a critical issue for obtaining an optimum magnetometer performance Ensure that the cable does not run parallel to any other cables that carry high level noise such as generator or echo sounder cables Ensure that the cable does not pass close to an outboard engine Ensure that any excess cable that 15 not paid out over the stern 15 coiled a figure of eight pattern this ensures a high level of noise cancellation Experiment with various cable routing options and note the 2 Check the integrity of the cable insulation Feed the entire length of the cable into the sea and measure the resistance between the screen contact of the Towfish connector and a probe placed into the sea If you measure less than 1M the cable insulation may have been damaged The cable should be laid out and carefully checked for physical damage If none of the above checks help cure or identify your problem then please contact your nearest service agent or the support department at Aquascan International Ltd 44 AX2000 Graphical Magnetometer User Manual Aquascan International Limited APPENDIX II AX2000 RAM INSTALLATION
33. the change in field strength as a survey progresses across the centre of an anomaly Levels below the reference level are related to areas where the field strength has been reduced by the presence of the anomaly The rate of change of field strength for an isolated anomaly is based on an inverse cube law hence the rapid build up to a peak which in reality has a broader the peak than the diagram illustrates Another way of expressing the law relating to change is that 2 times distance gives 8 times deviation change The other major influence on detect ability of an object is the presence of it s own permanent magnetic field this will itself produce a surrounding distortion in the earth s field Like the variations in permeability the strength of permanent magnetic field displayed will also be variable for different ferrous material The above described influences plus other general factors contribute to the overall size of the magnetic anomaly and hence detection distance these are listed below a Mass b Permeability c Permanent magnetism d Orientation within the earth s field e Scattering 4 3 MAGNETIC CONTOUR amp ANOMALY MAPS The above analysis has been concerned with the effects and detect ability of man made ferrous objects there are however many anomalies due to the natural occurrence of geological features that exhibit magnetic properties in many parts of the world these can have a serious impact on the interpretation of r
34. the magnetometer is away from the centre of operation such that the magnetometer gets a true initial sample of the earth s magnetic field 41 AX2000 Graphical Magnetometer User Manual Aquascan International Limited 15 2 DRIFT SEARCHING A particularly effective method of maintaining close proximity to the seabed is by drift searching this entails suspending the tow fish directly beneath the boat at a suitable height above the sea river bed to avoid snagging The essential factor with this method 15 to ensure that the tow fish 1s below the detection range of the search boat smaller boats are obviously more suited where this is carried out in fairly shallow water This method can also be used as a follow up to a search that has located an anomaly in a low visibility area by conventional towed searching but needs to be pinpointed very accurately for follow up diving activities The particular advantage being the ability to drop a shot line in very close proximity to the tow fish in response to magnetic indications The recommended procedure 15 as follows 1 With the tow fish and cable deployed such that the sensor 15 suspended horizontal and clear of the seabed or any anticipated hazards 2 A marker buoy is placed at the start of the first run as a reference point 3 The run 15 terminated after a set distance either by use of a positional navigator transits or by timing the run in conjunction with current speed 4 A marke
35. 1 The size and nature of the target This is without doubt the most fundamental single aspect of the decision making process By reference to the graph showing the tonnage distance relationship the maximum detection range can be established 2 The depth of water to be searched The general and maximum depth of water to be encountered 15 the second factor in order of importance to establish a lane with for the search Increasing water depth has the effect of reducing the distance to each side of the target that detection can be anticipated The local conditions at the time of search Whilst the general search pattern should establish it s lines along lines of Latitude EW or Longitude N S it is sometimes necessary to move away from the ideal to take account of strong tidal flow and wave action The effect of tide can in some circumstances be used to advantage for both control of direction and improved depth of tow fish against speed over eround The tow fish can be more easily deployed at depth whilst travelling with the tidal flow where the speed over ground can far exceed the speed in water 37 AX2000 Graphical Magnetometer User Manual Aquascan International Limited 4 The presence of other craft In busy waterways the affects of other vessels both moored or mobile can have a serious impact on the continuity of the survey where this cannot be avoided the positions of moored vessels should be noted for subsequently relat
36. 5 5525 25 gt 8 8 8 247 7 8 F 5 te 52 X 5 RRR ing is 55 009090900 T 2 8 5 8 5 5 ted listing from a logged file i hlighted read 18 associated with an anomaly and relates to the closest position obtained Analysing the Lat Lon readings shows that the course of the survey boat was predominately a Northerly direction to obtain a more true position the Latitude reading has to be modified by an amount that relates to the tow fish cable length deployed 25 5 55509 e 2 559500 ed 129 lt e 250 25 5 8 55 8 25 8 8 8 T t of typ The h 2 2 8 8 8 te 55 te ings e 8 gt lt CO MAIN MENU COMS AND NMEA 25 e te o e ious page is par KS te AS
37. 55555955 5555595 555555 555526555 E 0940090099296 099 99 99 49 99 9 9 9 9 905600560056 666006 5 0 50 25056656 8 2 5 25 5 8 5 lt 5 8 52 5 0 gt 920 52 T e 5 5 55 SS gt x 8 55 tet x 5 x 8 e gt 22 gt cem e 7000000000006 2575 5 5 55 50 292904024 55 e 55 50 x d lt gt gt e SOO KO SOOO 2 2 SS 3 8 gt xe 5 5 gt 5252 AX2000 export the contents of any logged data set to e EXPORT To export any of the data sets select DOWN LOAD DATA from the MAIN MENU 13 1 SPEED BAUD RATE ds between 600 and 4800 baud ion spee icat The AX2000 can support commun d ission spee d transm 1re Highlight the requ 1 2 Press ENT to select 32 AX2000 Graphical Magnetometer User Manual 13 2 SEND TO 1 Highlight the required peripheral 2 Press ENT to select 13 3 STYLE
38. 8 8 F uc I B OO 5 xX W te 5 25 fi 25 555555555 5555 555 5 552 8 RR 8 xS 8 55 55550 tes Z 8 7000000072 2 5 e 5 55000 225555555 5 555 5 e 8 ONE 8 22 5 8 x 59 5 lt 222 222 5 25 ns c 535 e OO 2050 0509005 9 005 9000 535 8 lt 0050000600 000 000600060 fi 535 SS 25 2 5 xS 25 535 52 15 56 45 lt Z 4 5 52 095999909090 25 lt 5 00 000000000 QB 8 aud Ze 1922 40 52 eo 50 0 e 2 0 X 552 e MAGNETOMETER SETUP 2 CoCOPIEoSS leased E 8 8 F x
39. AX2000 Graphical Magnetometer User Manual Aquascan International Limited AQUASCAN INTERNATIONAL LTD AQUASCAN HOUSE HILL STREET NEWPORT SOUTH WALES UK NP20 112 Aquascan International Limited Tel 444 1633 841117 255645 Fax 44 1633 254829 UNDERSEA DETECTION EQUIPMENT Email info aquascan co uk Website www aquascan co uk A 2000 GRAPHICAL MAGNETOMETER TYPES DET Operating Instructions This manual is copyright 2003 Aquascan Int Ltd all rights reserved This document must not be replicated in whole or part without the prior express permission of Aquascan International Ltd Issue 2 01 Sep 2003 AX2000 Graphical Magnetometer User Manual Aquascan International Limited CONTENTS 1 0 SYSTEM CODING 11 PACKING LIST CHECK 2 0 SYSTEM INSTALLATION 24 MOUNTING 2 2 CONNECTIONS 2 3 POWER SUPPLIES 2 4 TOWFISH INSTALLATION 3 0 PRINCIPLES OF OPERATION 3 1 PROTON PRECESSION 4 0 THE EARTH S MAGNETIC FIELD 4 1 MAGNETIC INCLINATION 4 2 MAGNETIC ANOMALIES 4 3 MAGNETIC ANOMALY amp CONTOUR MAPS 4 4 MAGNETOMETER SENSITIVITY 4 5 SENSITIVITY GRAPH 5 0 GETTING STARTED 5 1 POWER UP 2 2 RAM BANK CONFIGURATION MAIN MENU 5 31 SELECTING AN OPTION 5 32 SELECTING A SUB MENU OPTION 5 4 TERMINAL 5 41 CONTRAST 5 42 BACKLIGHT 5 43 BACKGROUND 6 0 POWER DOWN 7 0 SETTING UP THE MAGNETOMETER 7 1 MAGNETOMETER SET UP MENU 7 2 POLARISE TIME 7 3 MAGNETIC ZONE 7 31 GLOBAL TUNING 7 4 TOWFISH OFFSET 7 5
40. DATA The AX2000 can EXPORT the data set in one of two formats A GRAPHICALLY in the form of a histogram this presentation gives an easier format to visually analyse results for anomalies and to determine the degree of editing that may subsequently required for a particular survey data set B DATA STRING ASCII data in the form of a NMEA sentence this is a more practical form for archiving or loading in to a PC for subsequent editing filtering and mathematical manipulation for enhanced presentation 1 Highlight the required format 2 Press ENT to select 100 0 100 Data set title Data Record 07 39 Polarise time 2 0 No Of entries 00109 00000 52 35 874N001 45 004E 00000 52 35 888N001 45 012E 00002 52 35 888N001 45 012E 52 29 514N 005 0405 00001 52 35 894N001 45 012E 2 2 1 00001 52 35 902N001 45 010E iw 0 01 0344 00000 52 35 902N001 45 010E 00001 52 35 910N001 45 010E 0 B 00001 52 35 910N001 45 010E TYPICAL GRAPHICAL FILE TYPICAL ASCII FILE 13 4 DATA SET To select the DATA SET to EXPORT ERASE 1 Highlight data set 2 Press CURSOR LEFT RIGHT until the relevant data set number 1s shown 33 AX2000 Graphical Magnetometer User Manual Aquascan International Limited 13 5 BEST
41. ENU da 555555555600 555555 555555550 OOOO OOOO 55555555 5555552555555255555555555552 525255555555525555550522 4 8 W W A SE B 8 552 m W 8 0 x gt Z 8 8 8 5 55 TEX 8 tee B T 59 8 95505500 8 22 8 W 8 0 x 8 8 8 8 XX 550 B amp B RRS 5250 x 2 tet W 2 8 55 0 e 2 90500560 W 8 W 8 xX WB 5 55 W 555950505506 x x 55505660550 tet x 2 F x 8 33 x 9 9 8 gt 22 v BW 955555050560 BBW88 2 T 2 Z BW 55555 006 BW 5 W F W EES B 8 SEE SAX x 8 ts B8 7 x lt o 55 55 x 5 8 8 4 2 x 5 5 8 x 59 W 5 B B W es W 7 8 iN BW88 B X 9 B W SMAIIN AI
42. METER DISPLAY places the AX2000 7 6 MAGNETOMETER MODE 7 61 MAGNETOMETER DISPLAY NOTE r D un D D D 2 E Q ci lt ble alarm 15 25 1 bove and below ines a tone aud ted a two ica d In ve value ve Or two ways the In hown 1 IS S tion the trace exceeds devia AS 2 NUMERICALLY The digital value of the deviation in gammas nT 1s displayed at the lower right of the 1 GRAPHICALLY The magnetometer trace 1s scrolled across the screen right to left as the readings are updated screen 63 POSITION DISPLAY The current selected alarm threshold 19 indicated by horizontal dotted 1 7 62 ALARM LEVELS The magnet the zero level triggered 7 F PXXXRKRKKKRR RRR ERK RE 42000 ARR RR RAK RR RRR RARER RARER ERR RRR RRR ERE RRR REE RRR RE RRO ON IK IRI IIH IKK IKI RIKKI RIK 96 99 96 097 990 9959 09 099 095 0 0999 96 996 9 III 3199 9 4 999 994 99 93 KAKA KKK 99 9 109 AAAA AKKA AAK KKK KSK boo 04 ee X 8 8 Me 559 5 KX Ot 8 Me 8 5 15551 XXX 0 XXXI 222 LO POO 8 5 8 Men 01 9 2242 XXX Ot X Me S 224 et KSI 90 8
43. SWITCH OFF BY REMOVING POWER BY AN EXTERNAL SWITCH OR BY PHYSICAL DISCONNECTION OF THE POWER LEADS AS THIS electron WILL REVERT ALL INTERNAL SETTINGS TO THE INITIAL DEFAULT VALUES AND ALL STORED DATA WILL BE IRRETRIEVABLY LOST 7 0 SETTING UP THE MAGNETOMETER Toa option 7 1 MAGNETOMETER SET UP MENU NB The above settings related to these MAGNETIC ZONE options have been further optimised as per the diagram and conversion list below THE ABOVE DIAGRAM SHOWS THE ACTUAL MAGNETIC ZONE VALUES THAT SHOULD BE INTERPRETED FOR THE EQUIVELENT MENU SELECTION 2 POLARISE TIME 7 AX2000 Graphical Magnetometer User Manual Polarise time is the time interval devoted to energisation of the proton rich fluid in the tow fish the AX2000 has a polarise time default setting of 2 sec s and this 15 the recommended setting for the majority of applications The benefit of longer rather than shorter polarise times 1s to achieve a proportionately stronger burst of signal from the tow fish The benefit of increased signal strength is increased stability of measured results this in turn gives a corresponding flatter base line on the display allowing easier interpretation of small responses or the initial slow changes that occur with large targets at distance The peak to peak envelope of random variations in the baseline are generally referred to as the noise envelope Operating with the supply voltage at 24v instead of 12v as on the short
44. across the Towfish Phono Connector gt Connect a good quality multi meter across the core inner pin and metal outer contact screen on the Phono plug and check the resistance You should see a reading of about 9 to 15 depending on the actual sensor fitted and the cable length NB It is good policy to firstly check the multi meter s reading with the leads shorted together this provides a measure of what residual reading to take into account Symptom Signal Level Constantly High irrespective of Area tune selection Check the following I Check to see 1f excessive noise 1s affecting the signal Under conditions described in section 7 5 for setting up the Area Tuning place a ferrous metal object on top of the towfish and check to see if the signal level drops Under normal conditions putting a piece of ferrous metal in close proximity will dramatically reduce the signal level If the signal level remains high then background noise may be causing the problem see next page 43 AX2000 Graphical Magnetometer User Manual Aquascan International Limited Potential Noise Sources amp recommendations for elimination A Generator or other electrical noise on the power source It is highly recommended that you use a totally independent amp fully isolated battery An additional improvement can very often be obtained by use of a Sea Earth this 19 a direct connection between the ground ve battery terminal and the
45. b 24v dc supply c Data output facility for printer PC d NMEA 0182 0183 position input from navigation device AX2000 interconnect diagram EXTERNAL DEPTH DEPTH 0 ADJUST 12 24 V POWER PRINTER PC NAVIGATOR RS232 INTERFACE Made in Great Britain PROBE The Toroid probe is connected via connects to the AX2000 via the dedicated waterproof phono connector NB 1 It is essential to maintain this connection in a clean dry condition 12 24 POWER The dedicated 24v battery pack isolated is fed via the dedicated power supply unit NB 1 The display unit also has an internal 3 15A protection fuse 2 The AX2000DET 50 will operate as a system with 12v supply voltage However this will result in a reduced performance and should only be done for testing purposes PRINTER PC RS232 This provides both the connection point for the RS232 download lead and the Opto isolated lead for real time data transfer to a PC NB Although the standard RS232 download lead is also usable for real time data transfer it does not provide ground isolation Lack of ground isolation can lead to interference and hence reduce the stability of the readings NAVIGATOR INTERFACE 0183 data 15 fed to the connector via the NMEA lead supplied the connections are identified as NMEA DATA RED and NMEA RETURN BLUE AX2000 Graphical Magnetometer User Manual
46. c and serious magnetic survey measurements a magnetometer base station 15 set up in a recording mode this gives a time related database for comparison and post processing of results to enable spurious readings to be eliminated The Figure below shows the distribution of magnetic field strength over the major part of the earth s surface The relevance to the operator of this diagram is covered in the section that 9 AX2000 Graphical Magnetometer User Manual Aquascan International Limited refers to initially setting the correct operating ZONE The contours are shown in Gauss 100 000 nT 1Gauss 2 e a 0 gus A dA RY TH MANE TIC POE SES 1 4 T 3 N Q5 55 ol 217 7 2 41 MAGNETIC INCLINATION Another parameter of the earth s magnetic field that we have to take into consideration 15 the angle of inclination this is the angle at which the earth s field intersects with the horizontal plane of the earth s surface A general plot of values for this angle over the surface of the earth is Shown in the diagram below The angle of incidence can have some influence on the type of magnetic sensor deployed in various parts of the world In the Polar Regions the angle of inclination tends more towards the vertical whereas in the equatorial regions this angle becomes predominantly more horizontal The rel
47. cable versions of the A X2000 also has a beneficial effect on the amplitude of received signal and can compensate for the natural loss of signal when operating with short duration polarise times The combination of longer polarise time together with 24v operation will always produce the optimum achievable results and maximise tolerance to the effects of noise interference Finally because signal strength returned from the tow fish 1s also affected by the total intensity value of the earth s magnetic field the shorter polarise times can more readily be used in stronger magnetic field areas To set the required polarisation time 1 Highlight the required option 2 Press ENT to select option NB 2 SECS POLARISE IS THE MOST PRACTICAL SETTING FOR MOST APPLICATIONS 7 3 MAGNETIC ZONE AX2000DET 50 has the capability to operate a worldwide basis subject to pre set selection of the correct IPA 3 board and by MENU selection of the correct MAGNETIC ZONE The analogue section of the magnetometer 15 frequency selective by means of tuning the probe sensor further selectivity is obtained be means of a subsequent digital filter It is important that both of these sections are pre set for the relevant frequency of operation this frequency is directly related to the magnetic field strength in the area of operation The operator as such has to recognise the particular field strength total magnetic intensity of the operating zone
48. ctor layer cut back 1 Cable Retaining Nut 2 Cable grip 3 Sealing gland 4 Cable plug outer shell 5 Phono plug insert 6 Insert retaining ring 48 AX2000 Graphical Magnetometer User Manual APPENDIX VI MANUFACTURER CONTACT INFORMATION If you should need to contact Aquascan International Limited for advice on your purchase to order further equipment or to arrange a repair please use the following contact information Mailing Address Aquascan International Limited Aquascan House Hill Street Newport South Wales NP20 1LZ United Kingdom Tel 44 1633 255645 44 1633 841117 Fax 44 1633 254829 E mail Sales Enquiries sales 2aquascan co uk General Inquiries info aquascan co uk Technical Support support aquascan co uk Alternatively Web Address www aquascan co uk 49
49. e ANNONO ONAA OSOASA ROERNE RERNE RRI RIRE E EREEREER RSR bo 9 8 Eod 9 8 9 5204 A 8 2 MAN M pod 8 Eod 8 8 8 5 MS 0 8 2 52 pod 8 5204 5 8 8 Eod 8 5 5 5 8 Eod MAS 524 5 5 8 5 922 Se 9 po 9 24 52 8 lt 5 So M NS Dod 8 Pod 6 88 Aquascan International Limited ts graph 1n 1 I Lz es SERN 65 B AOSTO SETOS OESO N 566005660666 66606 066066690009 Ww8 BBBBR In the graphical mode the 2000 dedicates the screen to displaying the magnetometer survey results 2 sn Vn aa a4 A 2 Z O A aa x x aa Z gt as E lt gt lt gt Ci gt lt aa T operational mode i e it immediately begins to polarise the tow fish and update measurements Selecting MAGNETOMETER MODE from the MAIN MENU sets the AX2000 in its THE MAGNETOMETER MODE THIS IS BECAUSE OF THE Selecting MAGNETO
50. e statement 15 the TERMINAL SET UP menu this updates its configuration from within the sub menu To return to the main menu from the sub menu press the MEN key NB Changes to the initial default settings are maintained after power down by the internal memory backup battery 5 4 TERMINAL SET UP 18 imum setting 1s Aquascan International Limited F lt RRRRRY ARK RERWRRERERE ERK RR ERY RR EKER ERY RRR RERY RK RERWRR AREER ERK RE REE ERER ERY 040066092600 RASA NARRA NR RAS AA ATIS DE S ELS RRE TIS US HUS 22 OR OTt I AN TIS RRRA 101 lect TERMINAL SET UP opt imising se lt MIN AI AS CON BACK LIGHT BLACK BACK CZESCOI 8 2 0505 8 lt lt 8 8 5 2 5 55 8 5552 5555 8 8 Z 8 lt lt 8 SOS 2 5 8 lt lt 55 lt lt 252 35 50 RCIVVS amp c 552 Z 8 555 lt lt WSE DONE 7 2 7 2 7 I 7 0 1 0 tal histogram at the top of the ted by a small horizon 1Ca ing IS black or white to suit ambient light tely mina the MEN key ing by press eese TR SNAM
51. e the existing IPA 3 circuit away from the connector strips Fit the new IPA 3 circuit taking care to properly locate with the connector strips Replace and secure the metal screening can Carefully relocate the 2 halves of the AX2000 case and secure with the 4 corner screws Ensure that the new zone 15 also selected from the 2000 magnetometer set up menu 22 AX2000 Graphical Magnetometer User Manual Aquascan International Limited 7 4 TOWFISH OFFSET Although this has no direct functional significance within the AX2000 and will not effect the measurement and data storage functions it is off Importance to the subsequent processing and analysis of data The position stored by the 2000 15 related to the position derived from the antenna of the navigation receiver not the position of the actual magnetometer sensor The tow fish offset can be entered to a resolution of 5m and it 1s suggested that the cable can be marked with a suitable waterproof tape to give an indication of each 5m step Set the amount of FISH OFFSET to be comparable with the horizontal distance between the boat s navigation antenna and the position of the tow fish This must be set each time a different amount of cable is deployed or if the tow fish is towed relatively deep in which case an allowance has to be made for the vertical component which results in a reduced horizontal offset The offset entered 1s appended to each logged file that 1s sub
52. e the unit should be mounted behind some form of spray shield particularly when mounted on the console of Rigid Inflatable Boats RIBs and other similar type of high performance open boats Mounting the AX2000 display should take account of the central role the instrument takes during magnetometer survey operations this demands concentration and ease of keypad operation Although the LCD display has a wide angle of view it should be set to give the operator as direct a screen view as possible Apart from the normal compass considerations mountng the unit in close proximity to other general marine instruments should not cause any mutual interference The recommended minimum mounting proximity to a conventional compass is 20cm 8 for minimal effect If a central mounting position is not available then angle the unit as much as possible to present a view square to the operator AX2000 Graphical Magnetometer User Manual 2 2 CONNECTIONS AX2000DES amp DET systems are fitted with four waterproof connectors these are complete with protective caps The protective caps should be utilised both during operation to cover unused connectors and for protecting the instrument and cable end connections when unmated The interconnect system allows ease of disconnection and hence removal from the boat as required Connectors cater for the following needs a Multi way connection to the tow fish cable or indirectly via the extension lead
53. esults from a magnetometer The general magnetic geological nature of many parts of the world can be obtained by reference to magnetic anomaly maps these maps can be obtained through an Institute of Geological Science or similar body that is generally concerned with the compilation of geological data The degree to which we can tolerate a natural variable magnetic background depends on the proximity and intensity of the geological features in comparison to the size of the anomaly anticipated Where the geological feature is at some depth or distance from our magnetic sensor a localised anomaly can still be picked out quite readily from the more gradual change due to the background anomaly 13 AX2000 Graphical Magnetometer User Manual Aquascan International Limited field 5529 98 10087 plokaithitesional eradient deviation alarm GELE STEED ME DH ER eres ganna level datum 4 4 MAGNETOMETER SENSITIVITY The AX2000 sensitivity in terms of detection distance is based on its capability to resolve changes down to a resolution of 1 nano Tesla nT A magnetometer resolution of 1 nano Tesla is considered to be the optimum for mobile marine search and survey applications This InT value in terms of the total field measurement made gives a typical resolution in the order of 1 part in 50000 for measurements carried out in northern Europe for example resolution
54. evance of angle of incidence is that order to allow a marine magnetometer sensor to effectively retrieve signals irrespective of direction of tow requires that a reasonably high angle be maintained between the line of the sensor and the angle of inclination of the magnetic field In this respect the SOLENOID type sensor works well in the majority of areas of the world and particularly with an angle of inclination above 45 degrees The SOLENOID however becomes inefficient in areas with low angles of inclination particularly when the survey is predominately carried out in a north south direction which 15 essentially along the same axis as the earth s field To compensate for the low angle of inclination a TOROIDAL ring donut shape sensor is utilised this has a lower mean efficiency than the SOLENOID but when maintained horizontal is reasonably unaffected by change of direction within the earth s magnetic field 10 AX2000 Graphical Magnetometer User Manual 85 80 5 t D rr PIsunmPAewETCEQE NL 5 IL a 150 1857 350 122 90 6C LINES OF EQUAL INCLINATION 4 2 MAGNETIC ANOMALIES In order to understand how a magnetometer can locate a ferrous object such as a shipwreck or parts of a shipwreck 1t 1s necessary to understand the impact of such a ferrous object on the surrounding earth s magnetic field The diagram below shows a 2 dimensional view of such an object within the earth s
55. ey data being transmitted in one of two different formats 1 GRAPHICAL AX2000 outputs the data the form of a scrolling histogram annotated with the numerical magnetic deviations and position readings See fig 2 DATA STRINGS This option outputs the data in an alphanumeric sentence which is similar to the NMEA standard and contains each magnetic deviation measured together with the current boat position derived from the NMEA input when available N B DATA STRING SHOULD BE SELECTED WHEN LOGGING DATA ON AQLOGEDIT SOFTWARE Return to the MAGNETOMETER MODE sub menu by holding down the MEN key 20 AX2000 Graphical Magnetometer User Manual 11 0 DATA LOGGING 11 1 DATA LOGGING ON OFF Selecting this option either INITIATES logging of a new data set or terminates the data set currently being logged NB A shortcut to start and stop logging 15 by the use of the 1 keypad to start LOGGING and by use of the 2 key to stop LOGGING Also note that a key press of about 1 is necessary to ensure that the function is activated or de activated the logging status section of the display confirms this 11 2 DATA SETS The AX2000 automatically allocates a data set pointer to the set of data currently being logged The data set pointer is a unique number allocated to the data set to aid the AX2000 in locating the relevant data in it s RAM BATTERY BACKED MEMORY Because the data set number 19 uni
56. ing to logged results The area masked by the vessel can then subsequently searched to complete the survey The unexpected passing of a vessel within sensing distance of the tow fish can also corrupt a set of results NB When towing long cable lengths in busy waterways caution is necessary to avoid interfering with legitimate boat movements of other vessels and to minimise the danger of damage or at worst total loss of the cable and probe 5 The possibility existing of other detectable material within the search area or closely adjoining area As much information as possible about the search area should be obtained relating to wrecks debris pipes and cables Other more obvious structural features such as jetties piers and breakwaters etc also have to be taken account of both in the survey activity and during the post processing of the data obtained Even where the survey has to operate within the detectable distance of such structures it can still be possible to observe secondary localised magnetic anomalies by the difference in rate of change of magnetic field 6 The nature of the local geology which could influence the magnetometer readings Aeromagnetic anomaly maps can be of great assistance in establishing the general level of change that can be expected as the search progresses taking account of the direction of magnetic contours can also be influential in deciding the general direction of the search lanes Following the general
57. mited graphically and stored as data for later retrieval The measured units are quoted to nano Teslas nT gammas Deviation and relate to the small magnetic field strength changes that are being monitored The nano Tesla being a fractional part of the Tesla a unit of magnetic field strength 4 0 THE EARTH S MAGNETIC FIELD A reasonable understanding of the earth s magnetic field is fundamental to a successful operation of a proton magnetometer particularly when used for detection purposes The earth s field has a number of parameters the most important of which 15 the total intensity and this 1s the parameter measured and analysed by the magnetometer Under short term static conditions the total intensity value is maintained to a stability which allows the magnetometer to measure to a resolution of better than 1 nT gamma Co EARTH S MAGNETIC FIELD The Earth s magnetic field can be likened to that of a dipole such as a bar magnet this exhibits a symmetrical field distribution with the maximum field intensity appearing at the poles The earth s magnetic intensity however is not so symmetrical due to geological affects Over the major part of the world where magnetometers are likely to be deployed variation in total magnetic field strength 15 between 20 000 amp 70 000nT Magnetic storms and even effects from the sun sunspot activity can affect the total intensity value measured at any instant During mobile scientifi
58. n and the sounder will emit a rapid burst of clicks The version of software fitted to the 2000 16 also indicated a new screen will be display memory WI 55950500506 MOENIA SRR RI RR KKK RR KKK RR KR KKK KKK KKK 705050604 050550 09909 ORK 50505050 PSSS KNN IIIIN 5050506 Q PRO 50 ORR KR RRR KI 5904 190600606 eto 9 RRR RK RRR KKK RRR 5505606 50505 505050509 gt 5 DOO 8 X ci eA vm 5 7 Qu HE w tely 10 15 sec s During this time the AX2000 will perform its Avquascanm successfully completed DANA ES ASIN S 7 0 4 gt J 4 L 4 0 Press the red PWR button on the lower right of the keypad The AX2000 will respond by presenting e Q 5 Q 5 D Y XQ K PSSS gt p 0500504 9229 N AVA 9 9 0 09 9 9 9 0
59. on nT as distance from a given object changes this 15 seen as a factor of 8 change in nT for a change of 2 times in distance The implications of the above have a significant impact on pre survey planning and in particular lane width to be adopted for searching and accordingly the degree of control required for the survey boat The importance of probe height during survey for relatively small targets can also be determined from the graph particularly where it is used in conjunction with depth of water information Further information on these aspects 15 covered in the section of this manual concerned with Survey Techniques and Magnetometer Applications 14 Y T 3 2 c 5 lt 8 Q 3 v 8388901838 i HHHIEI MBRR ASEE ee rr mmm HEIHIN HIHI NEUEM iem TE T Aquascan International Limited t 7 ili pi IH ite iM 1 EH ME H 4 1 HHUH 1 TEO LARES S E T n br bee 4 deu bad 1 i m ip o i Lh 1 nr D m dir E EN es 0 t Ls didt TE
60. orizontal histogram at the lower left part of the screen indicates the amount of memory the geographical Lat Lon position 1s displayed digitally across the lower part of the screen space left during data logging NB Return to magnetometer mode sub menu by holding down the MEN button When an appropriate navigation aid 1s connected to the AX2000 v 7 64 MEMORY HISTOGRAM DISPLAY 7 65 DEPTH OF TOWFISH DISPLAY 7 7 MAGNETOMETER SETTINGS current memory status 15 If data logg memory r 2 gt D un D D D 2 T Q ci lt 26 ing options This allows a pre set level of magnetic deviation to be selected that will trigger the AX2000 audio sounder The value selected 15 indicated on the graphical display during operation The MAGNETOMETER SETTINGS sub menu presents the follow 7 71 ALARM nT lay bly the disp 1n Ing a reasona RR RRR RXRER RY TRE RER RY RRERE REX KEK ERETR RY REN RER RY RR XRK REX RETR ERETE EER ERER KER RRR EY NARRA A AA E RA REN eee eee eT PR SISOS ON 60955559 56559565555615005665500660550650550096065 aa C RR QUA Q Aquascan International Limited lar search application 2 T 555 2 25 8 8 8 X 25 55 8 8 lt 8 eS Bs 8 24 5 554
61. properties shows very little change over modest sized search areas Within predictable distances ferrous objects cause disturbances that can be detected and interpreted by the magnetometer whereas non ferrous metallic objects have little or no effect on the magnetic field and hence are not detectable directly by a proton magnetometer 3 1 PROTON PRECESSION The AX2000 proton magnetometer utilises the well established principle related to deriving an AC signal from the PROTON PRECESSION activity that can be induced in a hydrocarbon sample contained within the core of an electromagnet In the case of the AX2000 the electromagnet sensing element is formed by a multi turn inductor in the form of a solenoid or Toroid inductor The inductor 15 initially formed as an air cored coil but subsequently has the core filled with or immersed in a hydrocarbon fluid To measure the earth s magnetic field intensity the fluid must first be polarised This 1s the POLARISE state and is achieved by passing a dc current through the inductor for a predetermined time typically 2 seconds this 1s called the POLARISE TIME During this period the hydrogen protons in the core are progressively aligned with the direction of the created electromagnetic field Switching off the inductor current abruptly causes a large back EMF followed by proton activity PRECESSION in the core The protons are caused to precess about the direction of the earth s magnetic field at a rate p
62. que it can be noted and used by the operator to reference the required data set The AX2000 will increment the set pointer and allocate the new number every time logging is initiated The maximum data set pointer value is 99 once this value is reached the pointer will reset to and allocate 00 to the next data set opened The numbering system allows a maximum number of 100 individual data sets to be logged this 19 of course providing that the cumulative memory used does not exceed the 64k RAM standard version available Data set title Data Record 07 Polarise time 2 0 sec s No Of entries 0019 Dev lat long 00002 52 36 888N005 45 012E 00001 52 36 894N005 45 012E 00001 52 36 902N005 45 010E 00000 52 36 902N005 45 010E 00001 52 36 910N 005 45 010E 00001 52 36 910N 005 45 010E 00001 52 36 918N 005 45 008E 00000 52 36 926N005 45 006E 00003 52 36 926N005 45 006E 00006 52 36 932N005 45 006E 00011 52 36 932N005 45 006E 00022 52 36 940N005 45 006E 00024 52 36 940N005 45 006E 00026 52 36 948N005 45 006E 00022 52 36 948N005 45 006E 00012 52 36 958N005 45 006E 00008 52 36 968N005 45 004E End of data set 30 IS th the most extreme result YSKY OPPO HHH HH HHH HHH HHH HHH 009 0 666606065606 SRI IRIS I I Y BXRXKRRERKRKEXEXEKKKKHKHKHKHK OO ROGO XO RO NU NO NINH HHI HHH INI SAI NONI HI NIN IH ROKK RELL KKK RRR KKK K RAK KKH RAK
63. r 15 dropped to indicate the termination of the first run this enables subsequent runs to be terminated after the same distance 5 The tow fish is temporarily retrieved whilst the boat is returned to the start line 6 The second and subsequent runs are started at a set spacing from the first marker based on the calculated lane spacing required 7 The accuracy of the lanes can be confirmed by noting that the spacing at the terminating marker coincides with that at the start 42 AX2000 Graphical Magnetometer User Manual APPENDIX I TROUBLESHOOTING GUIDE Symptom Signal Level Constantly Low Check the following l Check that the supply battery has a sufficient charge gt If not place battery on charge and then re test or replace battery The demand on the battery alternates between a few hundred mA and a current in excess of an amp during the Polarise phase 2 Check the condition of the Phono insert of Towfish Connector the mating insert on the rear of the AX2000 Display gt If one or both of the connectors is badly corroded or loose fitting then they should both be replaced the system 16 supplied with a spares kit containing these inserts See Appendix V N B An authorised Aquascan service agent or a suitably qualified person should carry out this work Please contact your nearest Service Agent or the Aquascan support department before any work is carried out 3 Check the resistance
64. rea of seabed as a square or rectangular shape Buoy dropped alarm triggers Where the position for location of a wreck or object is known with a high degree of certainty the simple circular search method can be the more appropriate method The anticipated position is marked with a large bright PARALLEL LANE SEARCH coloured marker buoy this datum 15 then used to commence an expanding spiral search as shown in the diagram at some point in the search a response will occur which will indicate the general direction of the target Once the general direction 15 established the search becomes a number of short parallel runs across the anticipated area until the maximum peak reading is obtained in the case of a structure standing proud of the seabed the final confirmation 15 obtained a graphical echo sounder l 1 i d s w E ma a change ramnge asdisplay goes off scale 40 AX2000 Graphical Magnetometer User Manual Aquascan International Limited circular search pattern 15 particularly suited when graphical plotting navigator can be used in conjunction with the 2000 magnetometer In both the above search methods the procedure once the initial alarm threshold has been exceeded 15 the same if the boat position 1s obser
65. roportional to the strength of this field This proton activity induces an ac signal of a few microvolts in the coil the frequency of this signal 19 directly proportional to the strength of the earth s magnetic field The precise relationship between the frequency of the signal and the magnetic field strength 1s constant known as the gyro magnetic ratio The amplitude of the generated signal slowly decays as the individual protons gradually loose phase coherence The decay period is in the order of a couple of seconds before the signal becomes lost in noise The magnetometer must resolve the frequency of this signal within a fraction of a second to optimise the measurement This period immediately following polarisation is the DETECT or measurement period during which the search coil 19 connected to the amplifier The amplifier contains a filtering system to minimise the effects of noise and unwanted signal induced into the system The amplified signal 19 in turn passed on to the microcomputer which measures the frequency The use of a microcomputer 15 the key to providing an efficient measurement system together with many secondary but sophisticated features To measure the frequency of the precession signal the microcomputer compares the processed signal with its own crystal clock This technique enables the AX2000 to make very accurate measurements which can be displayed AX2000 Graphical Magnetometer User Manual Aquascan International Li
66. sequently created With an assumed 50m of cable deployed it can readily be appreciated that the same target response will occur at a radius of 50m for any approach assuming a magnetic response that is symmetrical with approaches to the target on reciprocal courses a resultant spread of 100m occurs This is fine on a single search and locate exercise in real time because this can be taken account of in the immediate position averaging from a number of passes however this 1s not practical when a comprehensive survey has to be carried out and in particular where this 1s for commercial or archaeological purposes and the survey 15 carried out using a highly accurate navigation system such as differential GPS The Fish offset function is critical where the results are to be compiled and processed to produce 2D amp 3D contour mapping Return to MAIN MENU by pressing the MEN key 23 AX2000 Graphical Magnetometer User Manual 7 5 TUNING THE MAGNETOMETER A facility is built in to the AX2000 to fine tune the magnetometer to the field strength in the general area of operation this enables maximum signal strength to be achieved in a similar way to that In which a radio receiver is tuned to get maximum reception This Is normally only required when the magnetometer is first used in a new area If the magnetometer is re located by some tens of miles it 15 worth rechecking the fine tune response To AREA TUNE fine tune the magnetome
67. set to 0 when CLEAR ALL is selected even though the total memory space of the AX2000 19 available for logging The data set number retains its arithmetic progression to 99 before resetting to 0 35 AX2000 Graphical Magnetometer User Manual 14 0 CONDUCTING A SEARCH 14 1 DEPLOYING THE TOWFISH The following points should be considered when deploying the tow fish probe 1 The ferrous mass of the operating vessel vessel itself must be considered as a mobile magnetic anomaly and as such has a detectable field distribution pattern that surrounds it this pattern will not be symmetrical and will vary as the vessel rotates within the earth s field A positive means of evaluating the safe distance for the probe is to initialise the magnetometer whilst the boat is maintaining a steady course once a stable reading has been established the probe 15 gradually drawn towards the towing vessel this should be done a couple of metres at a time allowing the magnetometer to update each time at some point a detection will be indicated on the magnetometer by a ve or ve change in the steady reading This exercise should be repeated with the vessel operated on different bearings with the result noted for each direction Once the minimum distance 15 established this should be taken as the minimal deployable length of cable and should be marked accordingly With this distance established the cable deployed the boat should be able to
68. ssible NB From the earlier stated laws relating to magnetic signatures of ferrous objects the general rule 15 anomaly responses increase by a factor of 8 for a change in proximity of a factor of 2 36 AX2000 Graphical Magnetometer User Manual NB 4 The requirement to add ballast weight to the tow fish DEPTH Of THE PROBE DEPENDANT ON LENGTH OF CABLE TOW SPEED SIZE OF WEIGHT In cases where the object to be detected is at a depth that would not allow positive detection with the tow fish at the surface requires that the tow fish be deployed at a height above bottom that would guarantee a response within the search parameters employed The use of a lead ballast weight close to the tow fish 1s a simple but effective method of achieving increased tow fish depth for a given speed Care should be exercised in the way the lead weight 15 attached to the tow cable the weight should never be attached directly to the cable but via an auxiliary line which should be taped to the tow cable at a maximum of 2 metre 6ft intervals The final section of cord attaching the lead weight should be the weakest link in the chain to safeguard the system in the case of an accidental foul of the ballast weight 14 2 SEARCH METHODS amp CONSIDERATIONS A number of search patterns and methods exist for the magnetometer survey these options are outlined in the following paragraphs The following factors influence the methods adopted
69. t N O a O window initial r 2 gt D un D D D ON 2 T Q ci lt 27 These options allow the user to choose what peripheral device the AX2000 interfaces with Once correctly configured the AX2000 will echo the survey results to the chosen device on 8 1 TX TO every update AX2000 Graphical Magnetometer User Manual 8 2 COMS Selecting the comma option instructs the AX2000 to output its data the standard ASCII format that an IBM compatible P C can utilise The interface lead provided allows reliable communication via a standard 9 pin RS232 serial port 9 0 NMEA INTERFACE The AX2000 has a fully opto isolated interface port that conforms to the NMEA 0182 amp 0183 1200 baud amp 4800 baud standards the purpose of this port 1s to receive navigation data in the form of Lat Lon positions Whilst modern navigation systems particularly GPS provide the NMEA 0183 format some of the older navigation receivers based on Decca and Loran only provide the NMEA 0182 format this features a position data stream identified as GLL and provides position data degrees minutes and decimal minutes to 2 places 1 to 1 100 of a minute The NMEA 0183 however is a more comprehensive interface standard and generally not only provides the GLL position data but also 1 or both of GGA amp
70. ter select the TUNE MAGNETOMETER option The AX2000 will respond by presenting the TUNE MAGNETOMETER sub menu which consists of 16 vertical histograms Once the TUNE MAGNETOMETER mode is selected the AX2000 automatically scans through the available tuning steps measuring the signal strength for each step The signal level generated by a particular tuning step is indicated by the height of the corresponding histogram The diagram shows the normal type of histogram response that can be expected and indicates that in this case 07 would be the correct step to enter This tuning scan feature can be a used as a very good health test for the magnetometer as either low signal or noisy signal conditions through interference can be readily interpreted Once the 16 steps have been scanned the AX2000 will prompt the user to ENTER TUNE VALUE If a single peak is not achieved but 2 adjacent steps give an equal amplitude either one can be selected alternatively an additional tuning scan can be carried out by pressing the ENT key this sometimes results in a more clearly defined separation between adjacent steps To select the appropriate tuning step 1 Enter the relevant number via the numeric keys 2 Press ENT to make the selection THE AX2000 WILL AUTOMATICALLY RETURN TO THE MAIN MENU 24 PROCESSOR INTENSIVE WORK THAT IS INVOLVED IT MAY SOMETIMES BE NECESSARY TO HOLD THE SELECTED KEY DEPRESSED FOR APPROX 1 SEC mod
71. tions in routing this cable are as follows 1 Avoid the cable passing close to the outboard inboard engine 2 Avoid the cable passing close to the main battery supply and charging cables 3 Where it 1s necessary to cross other cables do this at 90 degrees if possible 4 Any runs parallel to other cables should be kept as short as possible and with maximum spacing even spacing of a few centimetres can make an appreciable difference to the induced interference level 3 0 PRINCIPLES OF OPERATION AX2000 Graphical Magnetometer User Manual Aquascan International Limited The principle of operation of the proton magnetometer as a detection device is quite different to any other form of metal detection or sonar system being primarily a totally passive system The magnetometer is by definition a magnetic meter the proton magnetometer being an especially sensitive version allowing a high resolution capability in relatively low field intensi ties such as the earth s field As a measuring instrument it thus allows us to determine small changes in the strength total intensity of the earth s natural magnetic field and hence the presence of local anomalies A Proton magnetometer for wreck location measures the strength of local anomalies in the earth s magnetic field and for this it 15 extremely sensitive The earth s magnetic field value has a relatively good short term stability and in the absence of debris with magnetic
72. totally autonomous magnetometer survey system The inclusion of the latest in liquid crystal display LCD technology together with a numeric function keypad allows the flexibility associated with menu operation Battery backed memory 15 the additional major inclusion in the 2000 series thus allowing successive magnetic measurements together with position and depth data to be stored AX2DET50 systems are the Small Vessel Professional Grade Systems for operating in equatorial regions in particular and as such give a very high performance The Omni directional nature of the TOROID sensor resulting in a very stable measurement of the earth s magnetic field and hence a very optimised search tool for a very wide range of applications The depth of tow fish sensing transducer 15 also integrated into the towed assembly depth of tow fish 15 measured and included as a display parameter thus allowing optimised quality control over the survey and providing important additional data for post survey analysis I O facilities are available to allow data logging of water depth from a compatible NMEA based instrument this facility 15 provided to take advantage of a trend in marine instruments to provide both depth and positional data from a single NMEA port AX2DET 15 supplied with 128Kbyte of data logging memory representing a 6 hour survey buffer memory capability Duration and frequency of survey dictate the frequency of down loading to a
73. ved whilst monitoring the display for the change fange as E lane width js nta peak the initial response a line of position running through the anomaly CIRCULAR SEARCH PATTERN and at right angles to the course of the survey boat generally established Having established a line of Lat or Lon that runs through the anomaly it is just a question of establishing the peak reading when running at right angles to the initial course Once a peak reading has been established in the other direction the Lat Lon numbers for the anomaly have reasonably accurately been established some account needs to be taken for the layback of the tow fish for instance with 60m 200ft of cable deployed and the boat on a N S course the navigator readings need to be corrected by a factor of 0 030 minutes decimal Whilst on an E W course the correction factor will be related to the actual latitude this however at a Latitude of 50 degrees would relate to a correction factor of 0 050 minutes decimal NB There is no substitute for practising the art of magnetometer survey on a known target or range of targets before venturing on to the more serious activity of locating a totally new wreck The response although predicable from a familiar wreck does give a feeling of elation at mastering the black art of magnetometers CAUTION in all surveys with the magnetometer it is important to ensure that the initialisation of
74. y to plan deployment of the tow fish to some depth it is to this level that the horizontal line corresponds and which in essence becomes our artificial surface for the basis of calculations 39 AX2000 Graphical Magnetometer User Manual Aquascan International Limited 15 0 SEARCH PATTERNS 15 1 LANE SEARCHING The most common and practical survey method is by means of the parallel lane search in N S E W runs where a predetermined lane length and calculated spacing 15 1mplemented Lane integrity 15 maintained by relating the required spacing to decimal parts of units of Lat amp Lon as a for instance 1f a 200 Metre spacing is required and the survey 15 along an East West line the choice of 0 1 of a minute of latitude gives slightly less than the 200 Metre required Increasing or decreasing the distance 1s just a question of proportionately changing the decimal part of a minute related to 1 000 minute 2 metres For control of Longitude spacing during N S runs the same principal applies but the actual metres to minutes of Lon have to be derived from a table or chart for the particular Latitude of operations E g at a Latitude of 50 degrees an increment of 0 1 minutes of Longitude gives about 120 metres The parallel lane search 1s particularly appropriate where a large area has to be searched on a speculative basis or where the position of a wreck is very approximate PA it is also a more precise way of covering a pre planned a
75. ze tonnage and nature are known 3 The approximate lane width to be adopted AX2000 SENSIT 10 000nT 7 O0O0O0rT IEL gt E Cr 1r roteslas 1OOnT 1OnT DISTANCE meters By taking the maximum sensing distance for a given target and producing a simple scale diagram the optimum search lane width can be derived The procedure 15 as follows 1 Adopt a suitable scale say 2mm is equal to I metre 2 Draw a horizontal line representing the surface 3 Draw a vertical line downward from the horizontal line and perpendicular to it that 15 scaled to represent the mean depth Of the target 4 From the base of the vertical line depth draw a line to scale relating to the maximum sensing distance intersect with the surface horizontal line such that it creates the hypotenuse ofaright angle triangle 5 The distance established between the point of intersection at the surface and the top of the vertical depth line represents the maximum horizontal sensing distance to the target The above calculations have assumed that the tow fish 1s deployed either at or near the surface however It will be readily observed that as the depth increases for a given target size the corresponding horizontal component of the sensing distance reduces accordingly In situations where the depth of water exceeds the maximum sensing distance and it becomes necessar

Download Pdf Manuals

Related Search

Related Contents

Datacolor SpyderCube  CG3 PT ES GR NL    Dossier de presse  M16C/Tiny SKP Tutorial 2  取扱説明ョ  ASUS VS229H-P    

Copyright © All rights reserved. Failed to retrieve file