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Geometrics G-824A, Operation Manual

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Geometrics, Inc.                                  G-824 Magnetometer Manual                                                           

 

 

 

iv 

8.0 G-824B MAGNETOMETER ............................................................................................. 42

 

9.0  ACCESSORY SOFTWARE ............................................................................................ 43

 

9.1  Cesium Sensor Azimuth Program  -  CsAz ............................................................................................................. 44

 

APPENDIX A1. MODEL G-824A SPECIFICATIONS ............................................................ 45

 

APPENDIX A2. MODEL G-824B SPECIFICATIONS ............................................................ 46

 

APPENDIX A3. SENSOR INSTALLATIONS ......................................................................... 47

 

APPENDIX A4. CESIUM-VAPOR SENSOR THEORY .......................................................... 52

 

APPENDIX A.6 G-824A GENERAL BLOCK DIAGRAM OF SYSTEM COMPONENTS ....... 56

 

APPENDIX A.7 G-824B GENERAL BLOCK DIAGRAM OF SYSTEM COMPONENTS ....... 57

 

LIST OF FIGURES AND TABLES 

 
F

IGURE 

1

 

S

ENSOR

,

 SENSOR CABLE AND 

S

ENSOR 

D

RIVER 

M

ODULE

 ............................................................ 2

 

F

IGURE 

2

  

G-824

 

S

YSTEM AND 

A

CCESSORIES

 ............................................................................................ 3

 

F

IGURE 

3

 

A

CTIVE ZONE FOR THE CESIUM

-

VAPOR SENSOR

. ......................................................................... 4

 

F

IGURE 

4

  

S

HOWING INCLINATION OF EARTH

'

S MAGNETIC FIELD

 ............................................................... 5

 

F

IGURE 

5

  

M

AGNETIC FIELD INTENSITY AT THE 

E

ARTH

'

S SURFACE

. ........................................................... 6

 

F

IGURE 

6

  

M

ID

-

LATITUDE ZONE

. ................................................................................................................ 8

 

F

IGURE 

7

  

P

OLAR 

Z

ONE SENSOR ORIENTATION

 .......................................................................................... 9

 

F

IGURE 

8

  

E

QUATORIAL LATITUDE

 ........................................................................................................... 10

 

F

IGURE 

9

  

S

ENSOR MOUNT THAT PROVIDES FOR TWO AXES OF ADJUSTMENT

.

 

P/N

 

27530-04. .................. 11

 

F

IGURE 

10

  

B

LOCK 

D

IAGRAM OF 

G-824,

 POWER

,

 

PPS,

 AND COMPUTER CONNECTIONS

 ........................... 18

 

F

IGURE 

11.

 

S

CHEMATIC DIAGRAM OF DAISY

-

CHAINED 

CM-321

 COUNTER MODULES

. ................................ 20

 

F

IGURE 

12.

 

W

IRING DIAGRAM OF 

I

NTERFACE 

C

ABLE

. ............................................................................... 20

 

 

 
T

ABLE 

1.

 

G-824A

 STANDARD COMPONENT WEIGHTS AND DIMENSIONS

 .................................................... 3

 

T

ABLE 

2.

 

T

ROUBLE SHOOTING

 ................................................................................................................. 13

 

T

ABLE 

3.

 

G-824A

 STANDARD COMPONENT WEIGHTS AND DIMENSIONS

 .................................................. 15

 

T

ABLE 

4.

 

G-824A

 INTERFACE CABLE PIN

-

OUT

 ......................................................................................... 15

 

T

ABLE 

5.

 

E

XAMPLE OF 

CM-321

 DEFAULT OUTPUT DATA STREAM

. .......................................................... 19

 

 
 

Summary of Contents for G-824A

Page 1: ...824A CESIUM MAGNETOMETER Operation Manual COPYRIGHT 2014 P N 27731 OM Revision A7 GEOMETRICS INC 2190 Fortune Drive San Jose CA 95131 USA Phone 408 954 0522 Fax 408 954 0902 EMAIL sales geometrics co...

Page 2: ...ii...

Page 3: ...rminal Emulator 24 7 2 3 Serial Data Interface 25 7 3 Detailed configuration descriptions 25 7 3 1 Tera Term Terminal Emulator Program Setup 25 7 3 2 ASCII Data Output Format with 250 Hz Output Rate C...

Page 4: ...IVE ZONE FOR THE CESIUM VAPOR SENSOR 4 FIGURE 4 SHOWING INCLINATION OF EARTH S MAGNETIC FIELD 5 FIGURE 5 MAGNETIC FIELD INTENSITY AT THE EARTH S SURFACE 6 FIGURE 6 MID LATITUDE ZONE 8 FIGURE 7 POLAR Z...

Page 5: ...vides an extremely precise measurement of the earth s total magnetic field better than 1 part in 108 The design of the sensor optical package uses a split beam design which eliminates the need to opti...

Page 6: ...and an interconnect cable that is permanently attached to the sensor module and detachable from the sensor driver module These components are identified in Figures 1 and 2 The weights dimensions and c...

Page 7: ...Sensor driver module P N 27735 02 4 lbs 6 5 oz 2 kg 18 45 72 cm long including connectors 16 40 64 cm long x 2 1 2 6 35 cm square housing Carrying Case P N 27750 01 10 lbs 4 54 kg 18l x 9 5w x 15h 45...

Page 8: ...also known as one gamma or 10 5 gauss At the earth s surface in a nominal 50 000 nT field the Larmor frequency is about 175 kHz which is converted using a proprietary counting system in the internal...

Page 9: ...tion are 35 to 50 C 31 to 122 F humidity to 99 percent non condensing and an altitude range of 0 to 30 000 feet Like all magnetometers performance of the G 824A is primarily dependent upon the countin...

Page 10: ...efined by its magnitude and direction Unless the sensor is very near highly magnetic objects the local magnetic field will be almost entirely due to the earth s magnetic field In order for the G 824A...

Page 11: ...ed to adjust the sensor orientation for the best performance in the survey area The intensity information may be used as a check of the system operation Geometrics also offers a program called CSAZ wh...

Page 12: ...there may be some restrictions on the direction of flight Choosing one of the two recommended orientations will allow you to choose flight directions most suitable for your survey area Figure 6 Mid l...

Page 13: ...peration in polar latitudes This zone is shown as the shaded regions above and includes those areas where the absolute inclination of the Earth s magnetic field is greater or equal to 65 There are no...

Page 14: ...ed on 45 135 225 and 315 Normal sensor orientation for flight in a North South direction at the equator will be tilting the sensor backwards by 45 Similarly for East West flight the sensor should be t...

Page 15: ...G 824A sensor will provide a stable non magnetic attachment to the vehicle provide vibration dampening and allow the sensor s orientation to be adjusted with minimal effort One example of such a mount...

Page 16: ...performance problems may arise in two areas external electromagnetic noise and errors introduced from platform motion Electrostatic and electromagnetic signals from aircraft systems including other s...

Page 17: ...sample per second to 1000 samples per second This makes the system particularly useful when removing power grid noise or EM transmitter noise as the AC fields are not aliased in the digital data The C...

Page 18: ...Excessive current consumption Damaged Power and communications cable Defective sensor or electronics Replace cable Return sensor and electronics to Geometrics for repair Preventing a problem is almos...

Page 19: ...ent export restrictions the G 824A does not output the Larmor signal for external counting Digitized Larmor is provided to the user in RS 232 serial format from the G 824A serial port to a host comput...

Page 20: ...Circuit description of the external signal power interface cable Connector type SP02A 14 19P Pin Function Description A 30V power Magnetometer power 24 32VDC B GND Power ground C TxD From logging com...

Page 21: ...removed from the output data stream by editing the CM 321 configuration page There are several other configuration options that are discussed in detail below Figure 10 Block Diagram of G 824 power PP...

Page 22: ...Geometrics Inc G 824A Magnetometer Manual 18 Figure 10 Block Diagram of G 824 power PPS and computer connections...

Page 23: ...The default output data stream contains all printable ASCII characters with each sample terminated with a carriage return line feed sequence Table 5 illustrates an example of this format Character Des...

Page 24: ...nters they get echoed to the next An exception to this is the carriage return line feed sequence Here the carriage return is replaced by a comma and the line feed is ignored Thus one long concatenated...

Page 25: ...he FTDI USB Serial driver from http www ftdichip com FTDrivers htm Follow the instructions as prompted to install the Windows driver These two USB Serial adapters use the same Windows driver so it onl...

Page 26: ...de Ports COM LPT It should show USB Serial Port COMxx1 as below Note that the COM port that was assigned to this device by your computer will likely be different from the example shown COM25 1 xx here...

Page 27: ...menu and left click it 5 At the resulting USB Serial Port COMxx Properties menu left click the Advanced button 6 At the resulting Advanced Settings for COMxx change the Receive Bytes to the lowest va...

Page 28: ...nfiguration menu This is achieved through the host computer s Serial RS 232 Com Port If you already have a serial terminal program that allows bi directional serial communication through one of your h...

Page 29: ...order to communicate with the G 824 The following sections show examples of various configurations with different baud rates sample rates and output variables By following though the different config...

Page 30: ...26 Click on the Setup menu item and select Serial port to set the Baud rate Data bits Parity Stop bit and Flow control communications parameters The host computer is now ready to receive display and...

Page 31: ...t cable to the PPS output of the user s GPS receiver Note that the G 824 requires between 5 and 15 VDC pulses with a minimum of 10 millisecond pulse width Pulse polarity can be configured in the G 824...

Page 32: ...required 7 3 3 SET CYCLE TIME Data Output Rate The first step is to set the rate at which the magnetometer acquires and transmits magnetic field readings This is done by setting the time between each...

Page 33: ...of Output There will be a series of questions provided which allow us to reconfigure the data output format The current setting of each parameter is shown after each question It can either be left as...

Page 34: ...lay format Time display position 0 none 1 first 2 second etc 0 Number of decimals in seconds 1 Date display position 0 none 1 first 2 second etc 0 Fid number display position 0 none 1 first 2 second e...

Page 35: ...or display position 0 none 1 first 2 second etc 0 Sounder supply monitor display format Fluxgate supply monitor display position 0 none 1 first 2 second etc 0 Fluxgate supply monitor display format 12...

Page 36: ...Rate 115200 is not a standard Baud rate Press Y to ignore the warning and save the settings to FLASH Press any other key to abort Saving a file can take several seconds Press Y to proceed or any other...

Page 37: ...ows File Safe default values Not saved S N 824113 CM321 configuration Version 00 02 Mag Code Version 01 00 Build Date 8 29 2013 18 11 31 A Assign file name B Baud rates C Cycle time D Display all sett...

Page 38: ...can take several seconds Press Y to proceed or any other key to abort The operation complete successfully Checking There is no room You must erase a file first to make room before you can save The po...

Page 39: ...he configuration menu 5 Hit F to edit the Format menu You will see a series of questions that need to be edited as follows File Safe default values Not saved S N 824113 CM321 configuration Version 00...

Page 40: ...e 1 first 2 second etc 0 ADC 8 display format Aux input 1 display position 0 none 1 first 2 second etc 0 Aux input 2 display position 0 none 1 first 2 second etc 0 Aux input 3 display position 0 none...

Page 41: ...01 00 Build Date 8 29 2013 18 11 31 A Assign file name B Baud rates C Cycle time D Display all settings E Erase FLASH F Format of output G Gate control I Input voltages L Load from FLASH M Mode of op...

Page 42: ...rned on the magnetometer will synchronize its cycle time with the incoming PPS signal from the GPS such that one of the mag readings will correspond to the rising or falling edge of the PPS In additio...

Page 43: ...Normal 1 Aux1 2 Aux2 3 Aux3 4 Aux4 5 RS 232 1 Trigger PLL input sense 0 Rising 1 Falling 0 Enable external triggering 0 No 1 Yes 0 Enable phase locking 0 No 1 Yes 1 Concatenation Trigger character ASC...

Page 44: ...amined with a standard text editor The process of converting the XS3 format data into ASCII is explained in following steps Step 1 Decode XS3 into digits each byte of the input data is taken in turn a...

Page 45: ...es its place in the daisy chain order Thus there will be some garbled transmissions to the logging PC immediately upon power up 7 7 Hemisphere Locking Switch On the G 824 electronics console there is...

Page 46: ...r hemisphere locked postion 8 0 G 824B MAGNETOMETER The model G 824B magnetometer is a variant of the G 824A intended for use as a high performance base station instrument This model has the same dime...

Page 47: ...n and the size of the local gradient Positioning the sensor off the ground will reduce the gradients arising for the soil or from outcrops It is also important to provide a rigid support structure to...

Page 48: ...AZ Windows program is available on our Magnetometer CD and from our FTP site at ftp geom geometrics com pub mag Software see csaz setup exe Please read the manual that is included with the program for...

Page 49: ...ENSOR 2 375 60 32 mm dia 6 25 158 75 mm long 12 oz 339 g without cable 24 oz 680 g with cable SENSOR ELECTRONICS 2 5 63 5 mm dia 11 279 4 mm long 24 oz 680g CABLES Sensor to electronics 109 2 77 m Cab...

Page 50: ...m up to 6 sensors MECHANICAL SENSOR 2 375 60 32 mm dia 6 25 158 75 mm long 12 oz 339g without cable 24 oz 680 g with cable SENSOR ELECTRONICS 2 5 63 5 mm dia 11 279 4 mm long 29oz 822g CABLES Sensor t...

Page 51: ...Geometrics Inc G 824A Magnetometer Manual 47 APPENDIX A3 SENSOR INSTALLATIONS Figure A1 G 824A sensor and G 824A Bird components Figure A2 Airborne Stinger showing sensor mount...

Page 52: ...etrics Inc G 824A Magnetometer Manual 48 Figure A3 Aircraft fitted with stinger assembly Figure A4 Aircraft fitted with horizontal transverse and longitudinal gradiometer using faired wingtips and sti...

Page 53: ...Geometrics Inc G 824A Magnetometer Manual 49 Figure A5 G 824A Boom installation on Ultra lite autogyro Figure A6 Single sensor boom installation on Helicopter...

Page 54: ...Geometrics Inc G 824A Magnetometer Manual 50 Figure A7 Multi sensor 7 MTADS Helicopter installation for UXO survey Figure A8 Rack mount for airborne geophysical survey system...

Page 55: ...Geometrics Inc G 824A Magnetometer Manual 51 Figure A9 MTADS multi sensor array for UXO survey applications Figure A10 Multi sensor array on cart for UXO or archaeological surveying...

Page 56: ...s many spectral lines but only one line in the infrared region is employed All of the other light is blocked by a high grade optical filter The infrared line of interest is then passed through a split...

Page 57: ...tron energy level state that is measured to compute the ambient magnetic field strength When a photon of the infrared light strikes a Cesium atom in the absorption cell it may be captured and drive th...

Page 58: ...field measured in nano teslas gammas In the G 824A this radio frequency field is generated by a coil called the H1 coil that is wound around the tube holding the optical components When the R F field...

Page 59: ......

Page 60: ...7516 xx OPERATION AND TECHNICAL MANUAL 27731 OM SENSOR PACKAGE ASSEMBLY 27516 xx SENSOR DRIVER ASSEMBLY 27111 05 SENSOR CABLE ASSEMBLY 27553 01 SENSOR PHYSICS PACKAGE 320438 1 CARRYING CASE 27615 01 C...

Page 61: ...CAL MANUAL 27731 OM SENSOR PACKAGE ASSEMBLY 27516 xx SENSOR DRIVER ASSEMBLY 27111 05 SENSOR CABLE ASSEMBLY 27553 01 SENSOR PHYSICS PACKAGE 320438 220 CARRYING CASE 27615 01 CM 321 COUNTER BOARD 25790...

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