"user manual"
Contents
1. 8 3 2 7 MT E amp H postamplifiers and filters 8 3 2 8 Sixteen channel digital multiplexer 9 3 2 9 Programmable oscillator 9 3 2 10 Phoenix data acquisition system 9 3 2 11 MT preamplifiers 10 CPU q di PU EAR EACUS CR 11 3 2 13 DISC and tape d 11 3 2 14 Computer terminal 11 3 3 System 55 gt 4 seme ree keene 12 4 Magnetotelluric data acquisition system software 13 THEPOUUCLIODA Q y E BE a EAE Ra 13 OVEN VY OW oases desit v s ctr te te are nd ea tete e abs a eg es 13 4515207 bx LE RR Eee nei Sh 13 1 2 User S guid d coco E eI RO a 14 4 2 1 System initialisation 14 4 2 2 Answer file initialisation 15 4 2 3 Answer be BRETT 229 l 555 15 4 24 Data rb ed 16 4 2 5 Acquisition monitoring 16 4 2 6 trouble ShOOLTHQ0 4 soccer tree ES 17 4 2 7 Data archival and retrieval 17 amp 4 5 EMGR 009 a IC SED ata 18 4 2 9 FMGR UIS ePPOPS Z Oa cor S3 V X ORO D ENG SPP CAE ea 18 4 2 10 FMGR 033 errors2. C The information contained in this report has been obtained by the Bureau of Mineral Resources Geology and Geophysics as part of the policy of the Australian Government to assist in the exploration and development of mineral resources It may not be published in any form or used in a company prospectus or statement without the permission in writing of the Director BUREAU OF MINERAL RESOURCES GEOLOGY AND GEOPHYSICS CO RECORD Record 1986 36 BMR MAGNETOTELLURIC SYSTEM EQUIPMENT AND SOFTWARE 1985 by T Barton L Allen P Gardner TENN gt 1 n III Record 1986 36 BMR MAGNETOTELLURIC SYSTEM EQUIPMENT AND SOFTWARE 1985 Dy T Barton L Allen P Gardner CONTENTS Page Suma u wa eebe 1 L 2 2 The magnetortellurtc method vc re em 2 3 Magnetotelluric data acquisition system hardware 4 St OVER Oq a mapy anu Pd n Dd 4 Joc ucuz oh b REOR A RO ee RR 5 3 21 H Field sensor Ae 5 Seder H rield preanpl LE E 6 3 2 3 E Field sensor electrode 7 3 2 4 E Field preamplifier 7 3 2 5 MT calibrator and power monitor 8 3 2 6 MT postamplifier power 1
3. CR 19 should then be packed prior to restarting any further data acquisition D 42 4 3 MT UTILITIES 4 3 1 OVERVIEW There are several utilities used in conjunction with the MT DAS There are procedure files invoked from FMGR by typing a comma followed by the procedure file name and programs invoked with the RU command The procedure files are ARCH to archive the system using the HP program called FC PUDATA to archive and purge data files from the MT DAS onto tape STDATA to restore data files from tape onto disc PLINK to relink a specified program for the MT DAS While the programs are PUFT purges FTnnnn files from the system PUMT purges MInnnn files from the system CHEK checks the data from a specified channel on a specified MInnnn file FFT processes MTnnnn files into FTnnnn files TENSE processes FInnnn files into ROTTEN and or TIPPER files produces plots of apparent resistivity vs period phase angle vs period and rotation angle vs period screens out scattered rotated tensor analysis and phase data SCRAV averages screened data and formats it for 1D inversion The processing programs SCREE and SCRAV are described by Moore 1977 and wil not be dealt with in this document 4 3 2 PUMT AND PUFT PUMT and PUFT should be used with caution Data files are not generally purged but archived onto tape using the PUDATA procedure file When PUMT or PUFT is run a start
4. a 19 MT ka ikki uge er 20 43 1 OVEN IOW CS ve aaa CR EAD 20 8 3 2 JPUMT and PUPT 20 4 3 3 CHEK sss ad EN JEN 21 E dd CP els Sa eee eee 22 TENSE acc buch S hapu a SIR doe 22 T3505 ege atc E 22 4 4 Device do NC EE 24 4 4 1 10557 Phoenix A to D converter driver 24 4 4 2 ID 62 XDM 1 MUX interface driver 26 4 4 3 ID 70 SPO 1 programmable oscillator driver 27 4 5 Data acquisition system software components 29 4 5 1 Program MAGTL E 29 290 Pram IE acie go aw AO OR 32 4 9 9 Program UPDAT 3l 4 5 4 Subroutine READI OLD DATA 31 4 5 5 Subroutine READM OLD BUF LEN 31 4 5 6 Subroutine READR OLD 31 4 5 7 Subroutine DECID ICODE IARRAY 32 4 5 8 Subroutine DECODE ICODE IARRAY 32 4 9 9 Program EA CERES 33 1 5 10 S broutine GAINS oso r EARN rt EO dC eee s 34 7 9 LT ProUr dil BEE 35 2 9 Te ie E E VOR da cu a ed 35 5 513 Prodorom LES ux ace d dU CR UA pasu omis ee 35 De Re E OG a DIN esed ma Sor do aoi
5. 2 Power requirements 115 V AC 50 400 Hz BMR vocab no XDC CV7 The XDM 1 allows a number of devices to be connected to the CPU for input output operations For the MT system five channels were used as given below CHANNEL INPUT 0 amp Ey Preamp gain and filter settings Hz Hx amp Hy Preamp gain and filter settings 2 4 Postamplifier E amp H gain and filter settings When this device is used with the Geotronics preamplifiers the inputs require voltage level translation to TTL compatability To allow for this the inputs on channels O and 1 are optically isolated Details on this are given by Devenish 1979 Optical isolation is not required if the BMR constructed preamplifiers are used 3 2 9 PROGRAMMABLE OSCILLATOR Type BMR SPO 1 Power requirements 240 V AC 50 Hz BMR vocab no SPR 130 The 5 0 1 is a programmable oscillator that provides a number of output frequencies that are used to control the sampling rates Table 1 for the analogue to digital conversion carried out by the Phoenix equipment This device is controlled by the six least significant bits LSB of a 16 bit duplex register i e bits 0 5 Bits 0 4 determine the output frequency whilst switching of the oscillator is by bit 5 With bit 5 at logic 1 0 V the output is enabled and disabled when bit 5 is logic 0 12 V The cutoff frequency for an anti aliasing filter is selected by the three LSB of the duplex register Input settings of 00
6. CC is an Illegal Input Type HE for help EX to exit he two character command inputs are not followed by a carriage return as there is an automatic data transmission whenever a two character command is typed 4 2 2 ANSWER FILE INITIALISATION The IN command should be used with caution as it will preset the answer file to an initial state It is useful when the answer file is nonexistent 4 2 3 ANSWER FILE UPDATE After the UP command the user is prompted to update the answer file This command operates by displaying in turn the current values for various data items e g coil set used electode resistance and frequency band to sample For each displayed value a new value can be input or the return key pressed for no change To reset a value to zero 1 must be typed as in this system a zero is equivalent to pressing the return key The answer file is contains a character string of 54 letters and several numeric items The character string is used to contain details on the site It can be updated with the aid of a restricted editor function that interprets a by leaving that character position unalterd in the old string and a X by deleting the character in that position from the old string e g ANSWER FILE UPDATE survey Site is FINAL TESTING OF MAGTL AT BMR 27 3 84 New Site or cr AMA EEUU e LR New Site is FINAL TEST OF MAGTL AT BMR 28 3 84 The character string is updated first followed by the following numeric item
7. File 1982 938 unpublished 36 d EXTERNAL PUBLICATIONS JUPP D L B KERR D W LEMAIRE J MELTON B E MOORE R F MELSON R 8 VOZOFF K 1979 Joint magnetotelluric DC resistivity survey eastern Officer Basin Bulletin of the Australian Society of Exploration Geophysicists 10 209 212 SPENCE A G amp FINLAYSON D M 1983 The resistivity structure of the crust and upper mantle in the central Eromanga Basin Queensland using magnetotelluric techniques Journal of the Geological Society of Australia 30 1 16 WHITELY R J amp POLLARD P C 1971 A combined deep resistivity and magnetotelluric sounding in the Eromanga Basin Queensland Search 2 103 105 VOZOFF K KERR D W MOORE R F JUPP D L B amp LEWIS R J G 1975 Murray Basin magnetotelluric study Journal of the Geological Society of Australia 22 361 375 37 LV 6 REFERENCES BARTON T 1986 Broken Hill magnetotelluric survey 1984 Operational report Bureau of Mineral Resources Geology and Geophysics Australia Record 1986 4 CULL J P SPENCE A G MAJOR J A KERR D W amp PLUMB K A 1981 1978 McArthur Basin magnetotelluric survey Bureau of Mineral Resources Geology and Geophysics Australia Record 1981 1 DEVENISH A B 1979 Sixteen channel digital multiplexer BMR type XDM 1 Bureau of Mineral Resources Geology and Geophysics Australia Record 1979 48 LIU Y S B 1983 Magnetotelluric signal amplification and filtering a
8. These low signal levels determine the critical design parameters for the analogue portion of the equipment The magnetometer coils are buried underground to reduce noise interference and to provide thermal stability This requires two trenches 50 cm deep for the x and y components and a vertical auger hole 2 m deep for the z component The H preamplifiers are required to have extremely low noise levels typically 0 03 uV and include guarded differential inputs for chopper stabilisation to eliminate DC drift The E field is measured with electrodes 600 m apart These consist of cadmium rods inserted in porous pots containing supersaturated cadmium chloride solution These are placed in contact with moist earth in a covered hole to prevent enviromental disturbance and maintain a satisfactory ground to porous pot contact Multistrand copper wire is used to connect the electrodes to the E preamplifiers Shielding is not necessary because of the low source impedances involved The wire to the electrodes must be laid in a manner such that induced EMF s are not caused by wind moving the wires A complete description of field procedures is given by Word amp Hopkins 1971 and Vozoff 1972 The digital portion of the equipment is a computer based DAS with an interactive terminal The data are recorded in files on a disc memory and transferred to magnetic tape at the completion of recording at each site Recording at an MT site with the BMR system consi
9. ee kel rN Esch 4 5 10 SUBROUTINE GAINS MTHEADR BUFFER FORMAT Name site information AZIMUTH ICOIL SET Ex SEPARATION Ey SEPARATION Rx RESISTANCE Ry RESISTANCE NEXT FILE NO FREQ BAND FILES IN BAND No POINTS DIG INTERVAL 7X frequency band counts POSTAMP GAINS 5 EPRE FILTERS 3 EPRE GAINS 3 HPRE FILTERS 3 HPRE GAINS 3 FILTER PASSES 2 PRE AMPS 2 5 file record Record 1 Record 2 Record 3 Record 4 Record 5 Record 6 Record 7 Record 8 Record 9 GAINS is called by AQUIR in MAGTL to select all gains poles and zeros for the switch settings used and write them to the MTnnnn file GAINS is passed the following parameters DCB MT MTHEADR DCB of MT file that Poles Zeros etc are written to Contains passed switch settings from MTANS file GAINS operates by setting up the filter poles and zeros for channels 1 to 9 based on the switch settings found in MTHEADR and writing them to the MT file one record for each channel Al the poles and zeros data is read from an ASCII data file in list directed format The option of the use of two sets old Geotronics or new BMR of preamplifiers is allowed for by having four seperate P amp Z files one for each possible combination of old or new E or H preamps P amp Z11 17 old E and H preamps P amp Z21 17 new E and old H preamps P amp Z12 17 old E and new H preamps P amp Z22 17 new E and H pream
10. 1 2925 5 i 06 54 893 16 441 39 868 50 365 103548 7 7 7 071E 4 0 0 7 071E 4 0 0 1 0 postamp HP filter 1 7 071E 3 0 0 7 071 3 0 0 1 0 i uM 2 1214E 3 0 0 2 1214E 3 0 0 1 0 i V 7 071E 2 0 0 7 071E 2 0 0 1 0 i I 4 0 3536 0 0 0 3536 0 0 1 0 i I 5 1 7678 0 0 1 7678 0 0 1 0 I 6 7 07 0 0 m 071 0 0 1 0 XY 0 0 0 0 0 0 0 0 1 0 postamp HP filter zero Hx Channel Preamps 3100 Ex channel preamps No poles No fudgp s No zeros fudgz s 70 07 70 07 186 605 0 0 13 40 0 0 poles 2 5005E7 fudgp no zeros no fudgz s 0 5298 0 0 11 23 0 0 182 70 0 0 3061 0 0 0 6 0602E6 coil set 1 0 5260 0 0 11 26 0 0 173 70 0 0 8541 0 0 0 1 756E7 coil set 2 0 01647 0 004934 0 01196 0 01510 1 09685E 7 postamp LP filter 0 04528 0 01356 0 0329 0 01156 6 27717E 6 2 0 01647 0 04934 0 1196 0 1511 1 09777 3 i EN 0 7547 0 2258 0 5483 0 69248 0 484135 4 3 4298 1 0270 2 4924 3 1481 206 664 5 17 157 5 1359 12 469 15 739 1 2925 5 6 54 893 16 441 39 868 50 365 103548 7 S g uu 7 071E 4 0 0 7 071E 4 0 0 1 0 postamp HP filter 1 7 071E 3 0 0 7 071E 3 0 0 1 0 EE 2 1214 3 0 0 2 1214E 3 0 0 1 0 T ud 7 071E 2 0 0 7 071E 2 0 0 1 0 4 0 3536 0 0 0 3536 0 0 1 0 I 55 1 7678 0 0 1 7678 0 0 1 0 6 7 07 0 0
11. MT status file MTSTAT 18 exists and prompts the user for a valid input Valid inputs are AQ Start data AcQuisition AB ABort data acquisition immediately BR BReak abort data acquisition at next file EN ENd MAGTL disable printer if enabled EX EXit from MAGTL printer will remain enabled if enabled CU Display CUrrent answer file FI Display Flles collected in each frequency band HE Display the file IN INitialises the MT Answer File to 175 and 075 RE Enable the printer for hard copy REports RX Disable the printer ST Display survey STatus UP UPdate the answer file It then performs the specified command scheduling the appropriate program where necessary 4 29 iz 4 5 2 PROGRAM INITL INITL is scheduled by typing IN 1 opens the MTANS file and writes out the nine records below with default values for the fields Some of the defaults are meaningless and thus MTANS must be updated prior to data acquisition using UP MTANS file format Size Name Record 1 27 site information Record 2 AZIMUTH SET Ex SEPARATION SEPARATION Rx RESISTANCE Ry RESISTANCE NEXT FILE NO FREQ BAND FILES IN BAND No POINTS DIG INTERVAL k FN E E LE Record 3 5 POSTAMP GAINS 5 Record 4 3 EPRE FILTERS 3 Record 5 3 EPRE GAINS 3 Record 6 3 HPRE FILTERS 3 Record 7 3 HPRE GAINS 3 Record 8 2 FILTER PASSES 2
12. The ratio of induced electric to magnetic field at various frequencies is used to calculate apparent resistivity i e the resistivity of a uniform earth which gives the measured E H ratio as a function of frequency Apparent resistivity curves are then used to produce one dimensional 1D layered models and finally in some cases two dimensional 2D resistivity models In the MT technique the horizontal magnetic field H field is usually measured with the corresponding induced electric field E field in two orthogonal directions on the Earth s surface In practice the H field is measured by the use of three orthogonal induction coil magnetometers Hx Hy Hz and two electrode pairs Ex Ey Each pair is 600m in length centred on the magnetometer array location The signals are amplified filtered and recorded using a computer based data acquisition system DAS which also provides a facility for preliminary in field data processing All data is then stored on magnetic tape for further processing prior to final interpretation 3 MAGNETOTELLURIC DATA ACQUISITION SYSTEM HARDWARE 3 1 OVERVIEW The methods used for recording MT data depend to a large extent on the spectra of the signals being measured Magnetic field strengths decrease rapidly at high frequencies to the order of 1 picotesla 1 pT however with the use of induction coil magnetometers a dynamic range of 100 dB is accommodated providing increased sensitivity at higher frequencies
13. by k 137 microvolt gamma Hz 3 on the low frequency asymptote Plots of the transfer function amplitude and phase vs frequency are given by Word amp Hopkins 1971 3 2 2 H FIELD PREAMPLIFIER Type Geotronics Model MTH 4 S No 4 003 Number of channels 3 Connectors Front panel Input 2 copper binding posts Input guard shield yellow post Signal common black post Calibration red amp green posts Rear panel Output 2 paralell BNC connectors Gain steps 1800 18000 180000 Filter 4 pole 4 zero band reject filter with notch centred on 50 Hz Noise 0 20 uV pp rti 0 002 25 Hz 0 10 uV pp rti 0 002 2 Hz 0 05 uV pp rti 0 002 0 125 Hz rti referred to input Chopper frequency 2 KHz Input voltage SmV undistorted 45 V abs max Output voltage 5 V max Input impedance 1 45 kohm 10 mf Common mode rejection 150 dB at 1 Hz 143 dB at 10 Hz 124 dB at 100 Hz Power requirements 115 V AC 50 Hz 30 W max Operating temp 0 C to 50 C BMR vocab no MMA 025 The H preamplifier is a low noise guarded differential input chopper carrier amplifier Three gain settings are available for each of the three channels Each channel also has two signal monitors One is a zero centre volt meter thath reads the preamplifier output The other is simply a red light that will latch on if either the chopper carrier amplifier or the output DC amplifier approach saturation It is r
14. file number and stop file number must be provided as run parameters These programs will run faster if a cartridge number is specified as a third parameter e g RU PUFT 3 45 20 This will purge files in the range 0003 to FT0045 from cartridge 20 PUMT and PUFT wil display on the VDU the file names as they are purged on qS 4 3 3 CHEK Checks the data in an MT file by a graphic display of the signal in a specified channel i e RU CHEK MT0055 will check a channel of data on file 55 CHEK will open the specified file or terminate with an error if it can not be found on cartridge 19 The file name and its header record are then written on the screen CHEK can be terminated by typing EX or continued by hitting the RETURN key e g FMGR RU CHEK MTO5OO File MT0500 is BROKEN HILL 1984 SITE 14 YANCOWINNA CREEK FMGR Note that CHEK will clear the screen when run and that it will not echo the EX typed in If it is continued by hitting the RETURN key CHEK will ask for a channel number only one channel can be looked at an offset and an X and Y scale factor e g File 0500 is BROKEN HILL 1984 SITE 14 YANCOWINNA CREEK kkkkkkkkkkkkk Enter Channel lt 3 gt look at channel 3 Enter Offset Defaull is 1 lt 100 gt start at sample 100 Enter Y Scale Default is 20000 lt return gt Y scale defaulted Enter X Scale factor Default is 1 lt return gt X scale
15. novel design 0 Bureau of Mineral Resources Geology and Geophysics Australia Record 1983 8 MOORE R F 1976 Graphic presentation of magnetotelluric data Bureau of Mineral Resources Geology and Geophysics Australia Record 1976 97 MOORE R F 1977 Screening and averaging magnetotelluric data prior to one dimensional inversion Bureau of Mineral Resources Geology and Geophysics Australia Record 1977 8 SPENCE A G amp KERR D W 1982 BMR magnetotelluric system software 1980 Bureau of Mineral Resources Geology and Geophysics Australia Record 1982 35 VOZOFF K 1972 The magnetotelluric method in the exploration of sedimentary basins Geophysics Vol 37 No 1 98 114 WORD D amp HOPKINS G 1971 Instruction manual Magnetotelluric system analogue data acquisition system Geotronics Corporation Austin Texas U S A 38 APPENDIX 1 HEWLETT PACKARD MANUALS edition and update number were current at the time of the system being operational Manual Title Part Number Printed Update Date Getting Started A Series Computer 5955 8813 4 82 Decimal String Arithmetic Routines 02100 90192 10 79 HP 1000 L Series Computer 1 0 Interface 02103 90005 4 82 HP 1000 A600 Reference Manual 02156 90001 3 82 HP 1000 600 Installation amp Service 02156 90002 3 82 HP 2622A 2623A Display Terminals 02622 90008 6 81 HP 2623 Graphics Terminal 02623 90001 7 81 HP 12005A Asynchronous Serial Interface 12005 90001 1 80 3 4 82 H
16. 0 or 111 disable the filter The oscillator is interfaced with the CPU which provides the logic control for the output frequency selection 3 2 10 PHOENIX DATA ACQUISITION SYSTEM Type Phoenix Data Inc Model 6915 3754 amp Model PDI Standard Subsystem Interface Power requirements 240 V AC 50 Hz BMR vocab no XDI DA3 The 6915 is an analogue to digital converter which is used in conjunction with the PDI Standard subsystem interface for the acquisition of MT data The sampling rates are controlled by the CPU via the programmable oscillator and the digitised data is sent to the CPU for storage onto disc Full details on this equipment is given by Phoenix Data Inc 1976 1977 3 2 11 MT PREAMPLIFIERS Type BMR MT Preamplifiers S No s 1 2 3 4 5 Number of channels 5 Number of channels 5 Connectors Front panel Input 2 red binding posts Signal common silver binding post Rear panel Output BNC Power Cannon 14 5 5 A 415 V B 15 V C OV Gain steps 0 00 1000 Filter 50 Hz notch filter 38 6 dB Input Voltage 1 V undistorted Output voltage 12 V Input impedance 2 2 mohm Common mode rejection 64 4 dB at 10 Hz External power 15V DC Internal power 12 V DC 5 V DC Operating temp 0 C to 50 C BMR vocab no MMA 026 These preamplifiers were designed and constructed by BMR to replace the Geotronics units At the time of writing these preamplifiers had not been field te
17. 007 SN SNAP LA 16 0008 0009 18 0010 17 0011 19 0012 20 0013 16 0014 0015 DEFINE INITIALLY RP ED PROGRAMS 0016 RP D RTR 0017 0018 RP COMND 0019 0020 RP FMGR 0021 ST WE LC OM 0022 0023 LINK EDIT TO ALLOW EDITING SYSTEM FILE 0024 0025 LK EDIT 0026 0027 LK FC 0028 0029 LK LINK 0030 RP HELP 0031 RP CURNT 0032 RP UPDAT 0033 RP FILES 0034 RP STATS 0035 RP AQUIR 0036 RP INITL 0037 RP PUFT 0038 RP FFT 0039 RP TENSE 0040 RP MTPLT 0041 RP CHEK 0042 RP MAGTL 0043 0044 END RP LK PHASE 0045 END 0046 0047 DEFINE SWAP FILES 0048 SW SWAP SW 18 0049 0050 END 43 APPENDIX 4 SYSTEM BOOT FILE FILE SYSTEM 16 4 0001 EC 0002 0003 DEFINE SYSTEM AND SNAP FILES 0004 SY PRMSYS 0005 SN SNAP 0006 0007 MC 18 0008 MC 17 0009 16 0010 0011 DEFINE INITIALLY RP ED PROGRAMS 0012 RP D RTR 0013 0014 RP COMND 0015 0016 RP FMGR 0017 ST WE LC OM 0018 0019 LINK EDIT TO ALLOW EDITING SYSTEM FILE 0020 0021 LK EDIT 0022 0023 LK LINK 0024 0025 END RP LK PHASE 0026 END 0027 0028 DEFINE SWAP FILES 0029 SW SWAP SW 18 0030 0031 END 44 APPENDIX 5 LOGICAL UNIT LU TABLE LU DEVICE 16 7908A Disc cartridge 16 17 7908A Disc cartridge 17 18 7908A Disc cartridge 18 19 7908A Disc cartridge 19 20 7908A Disc cartridge 20 24 7908A Tape drive 30 Phoenix A to D converter 31
18. 1647 0 004934 0 01196 0 01510 1 09685E 7 postamp L 0 04528 0 01356 0 0329 0 04156 6 27717E 6 0 01647 0 04934 0 1196 0 1511 1 09777 3 I 0 7547 0 2258 0 5483 0 69248 0 484135 3 4298 1 0270 2 4924 3 1481 206 664 17 157 5 1359 12 469 15 739 1 2925 5 54 893 16 441 39 868 50 365 103548 7 7 071E 4 0 0 7 071E 4 0 0 1 0 postamp 7 071E 3 0 0 7 071E 3 0 0 1 0 2 1214E 3 0 0 2 1214E 3 0 0 1 0 7 071 2 0 0 7 071 2 0 0 1 0 0 3536 0 0 0 3536 0 0 1 0 1 7678 0 0 1 7678 0 0 1 0 7 07 0 0 7 071 0 0 1 0 0 0 0 0 0 0 0 0 1 0 postamp 40 No Zeros filter filter Zeros filter filter No fudgz s No fudgz s 4 C O1 gt LA n3 IG OQ Pa CO ero 47 Hz Channel Preamps 3100 S Ex channel preamps No poles No fudgp s No zeros fudgz s 70 07 70 07 186 605 0 0 13 40 0 0 poles 2 5005E7 fudgp no zeros no fudgz s 0 5292 0 0 11 14 0 0 176 25 0 0 9896 0 0 0 2 009E7 coil set 1 0 5306 0 0 11 05 0 0 179 13 0 0 4449 6 0 0 9 262bE6 coil set 2 0 01647 0 004934 0 01196 0 01510 1 09685E 7 postamp LP filter 1 0 04528 0 01356 0 0329 0 04156 6 27717E 6 E 0 01647 0 04934 0 1196 0 1511 1 09 77 3 0 7547 0 2258 0 5483 0 69248 0 484135 i 4 3 4298 1 0270 2 4924 3 1481 206 664 z d 17 157 5 1359 12 469 15 739
19. 5 mm case 0 0 76 mm cap flange 0 0 114 mm weight 38 6 kg MMM 025 40 C to 100 C Type coil set 1 coil set 2 Dimensions BMR vocab no Operating temp The model MTC 4 sensor is an induction coil magnetometer The coil itself is wound on a laminated moly permalloy core then potted in polyurethane rubber and encased in a stainless steel jacket There is a Farady shield between the case and coil The two coil signal terminations are made with special copper binding posts the shield terminal is a standard binding post All three terminals are mounted on a phenolic header located in the end of the coil The cable is connected to the terminals via a self sealing cap which is bolted to the head of the coil he sensor cable Geotronics type H36 003 consists of three individually shielded twisted pairs of untinned stranded copper wire The cable and individual pair jackets are made of polyurethane rubber and the conductor insulation is polyethylene Connections between the coils and the H preamplifiers are made directly to the copper binding posts of the respective instruments In field operations the sensors were used as follows H COMPONENT SERIAL No s CONNECTIONS Hx 1005 1014 Yellow Green Hy 1006 1015 Brown Black Hz 1007 1016 Red Orange The output terminal marked is positive for an increasing positive H field directed from the terminal end to the opposite end of the sensor he coil sensitivity is given
20. 62 is the RTE A interface driver used with the BMR XDM 1 multiplexer and a Parallel Interface Card PIC It uses the folowing system entry points WRIT to write 1 word into the users data buffer DIOC to return the address of the Interface Table IFT Read and Control EXEC request only are allowed Write requests are rejected with the appropriate error code set The following error codes are returned in the A register 0 No error Illegal request write 2 Illegal interupt 3 MUX timed out ID 62 is invoked by a user EXEC call with the following format CALL EXEC 1 ICNTWD IBUFAD NUMBER IUNIT where 1 1 specifies a read ICNTWD specifies the MUX LU 32 in the lower 6 bits and the starting channel in the next 4 bits 6 to 9 IBUFAD is the buffer address where the driver will put the data read off the specified channels NUMBER is an option that specifies the buffer length and hence the number of channels to read This defaults to 1 IUNIT is an option that specifies the unit number of the MUX where several MUX s are chained together It is not normally used and will default to O 26 ID 62 uses the following entry points into the Device Table DVT DVT ENTRY POINT USAGE ENTRYPOINT UPON ENTRY TO ID 62 UPON EXIT DVT15 contains EXEC request not used and subfunction to select starting channel number DVT16 contains EXEC buffer contains address error code DVT17 contains EXEC buffer contai
21. 7 071 0 0 1 0 7 0 0 0 0 0 0 0 0 1 0 postamp HP filter zero q 4 Hy Channel Preamps 3100 Ex channel preamps No poles fudgp s No zeros fudgz s 70 07 70 07 186 605 0 0 13 40 0 0 poles 2 5005E7 fudgp no zeros no fudgz s 0 5464 0 0 10 66 0 0 183 90 0 0 9361 0 0 0 1 935E7 coil set 1 0 5431 0 0 10 69 0 0 182 30 0 0 7694 0 0 0 1 581E7 coil set 2 0 01647 0 004934 0 01196 0 01510 1 09685E 7 postamp LP filter 1 0 04528 0 01356 0 0329 0 04156 6 27717E 6 2 0 01647 0 04934 0 1196 0 1511 1 09777E 3 I I 0 7547 0 2258 0 5483 0 69248 0 484135 4 3 4298 1 0270 2 4924 3 1481 206 664 i 5 17 157 5 1359 12 469 15 739 1 2925 5 i 6 54 893 16 441 39 868 50 365 103548 7 1 m 37 7 071E 4 0 0 7 071E 4 0 0 1 0 postamp HP filter 1 7 071E 3 0 0 7 071E 3 0 0 1 0 E 2 1214 3 0 0 2 1214E 3 0 0 1 0 j i T m 7 071 2 0 0 7 071 2 0 0 1 0 4 0 3536 0 0 0 3536 0 0 1 0 i 1 7678 0 0 1 7678 0 0 1 0 i 6 7 07 0 0 7 071 0 0 1 0 a 5 EE 0 0 0 0 0 0 0 0 1 0 postamp HP filter zero NOTE Denotes that these values will need to be replaced with new poles and fudgp s when new H channel pre preamps are built 42 gt APPENDIX 3 MT SYSTEM BOOT FILE FILE BCF01 16 4 0001 EC 0002 L 0003 EC 0004 0005 DEFINE SYSTEM AND SNAP FILES 0006 SY OUTPUT LA 16 0
22. AT to read and update an integer variable One integer parameter OLD DATA is passed to this subroutine It operates by reading a response from a users terminal into the INTEGER variable called NEW DATA READI then checks if NEW DATA is non zero and if so updates OLD DATA according to the value in NEW DATA If NEW DATA is negative OLD DATA is set to zero if NEW DATA is positive OLD _ DATA is set to the value of NEW DATA 4 5 5 SUBROUTINE READM OLD BUF LEN READM is a subroutine called by program UPDAT to read and update an integer variable One integer array OLD BUF of length LEN is passed to this subroutine It operates by reading a response from a users terminal into the INTEGER buffer called NEW BUF READM then checks if NEW BUF is non zero and if so updates OLD BUF according to the value in NEW BUF If NEW BUF is negative OLD BUF is set to zero if NEW BUF is positive OLD BUF is set to the value of NEW BUF 4 5 6 SUBROUTINE READR OLD DATA READR is a subroutine called by program UPDAT to read and update a real variable One real parameter OLD DATA is passed to this subroutine It operates by reading a response from a users terminal into the REAL variable called NEW DATA READR then checks if NEW DATA is non zero and if so updates OLD DATA according to the value in NEW DATA If NEW DATA is negative OLD DATA is set to zero if NEW DATA is positive OLD DATA is set to the value of NEW DATA 31 2 4 5 7 SUBROU
23. E PRE AMPS H PRE AMPS CALIBRATOR 24V DC POWER SUPPLY SIG GENERATOR PATCH BOARD PROGRAMABLE OSCILLATOR A600 CPU HP7908A DISC amp TAPE DRIVE A D INTERFACE PHOENIX A D CONVERTER MULTIPLEXER 27 N 20 48
24. ENTS The Data Acquisition System DAS is controlled by the main control program MAGTL is a FORTRAN program that operates by executing the appropriate program upon receipt of a two character command It also initialises the status file MTSTAT The initialization process is performed by MAGTL executing the program INITL upon receipt of the IN command This is NOT done automatically INITL simply sets up the MTANS file with default values The program UPDAT must then be run via the UP command to put meaningful site information into the MTANS file including the switch settings on the amplifiers which are read from the MUX The actual data acquisition is performed by the program AQUIR executed via the AQ command AQUIR creates the specified number of MTnnnn data files placing the site information from the MTANS file at the head of each file followed by records containing the gain poles and zeros for each channel as determined by the switch settings in the MTANS file It also updates the status file MTSTAT Various programs exist to monitor the status of the system CURNT displays the site information contained within the MTANS file Any incorrect fields can then be corrected using UPDAT STATS displays the data acquisition status read from the MTSTAT file FILES displays the number of files collected in each frequency band 4 5 1 PROGRAM MAGTL MAGTL is the main control routine for the MT DAS It operates by ensuring that the
25. IONS option allows the user to input the following option ROUTINE uses the default values NPD Number of data points per decade default 10 TCENTRE Cutoff or centre period default 10 COHLIM 2 Lower and upper coherency limits default 0 8 0 8 SKEWLIM 2 Upper and lower skew limits default 1 1 23 4 4 DEVICE DRIVERS Three drivers were written for the MT DAS They are The Phoenix driver ID 57 The 5 0 1 oscillator driver ID 70 The XDM 1 MUX driver ID 62 4 4 1 ID 57 PHOENIX A TO D CONVERTER DRIVER ID 57 is the RTE A 1 interface driver used with the Phoenix 6915 analogue to digital converter and a Parallel Interface Card PIC It uses self configuring Direct Memory Access DMA and the folowing system entry points SELR to select the correct map 1 of 32 system or user DIOC to return the address of the Interface Table DMPR to report DMA parity errors IFTX to return address of current interface extension Read and Control EXEC request only are allowed Write requests are rejected with the appropriate error code set The following error codes are returned in the A register 0 No error 1 Illegal request write 2 Illegal interupt on DMA 3 Phoenix timed out 10557 uses DMA to read off LU 30 the Phoenix analogue to digital converter It configures the Phoenix to read 5 channels of data Ex Ey Hz Hx Hy with external clocking in a sequential mode see the Phoenix manu
26. P 12006A Parallel Interface Ref Man 12005 90001 1 80 2 3 82 HP 12008A PROM Storage Module Ref Man 12008 90001 1 80 2 3 82 HP 12009A HP IB Interface Ref Man 12009 90001 1 80 2 9 82 VIS User s Manual 12824 90001 1 83 DOS RTE Relocatable Library 24998 90001 10 81 HP IB in the HP1000 User s Guide 59310 90064 12 83 MACRO 1000 Reference Manual 92059 90001 6 83 Edit 1000 User s Manual 92074 90001 7 82 RTE A 1 Installation Instructions 92077 90001 2 82 RTE A 1 Operator s Guide 92077 90002 6 83 1 12 83 RTE A 1 Utilities Manual 92077 90004 6 83 4 12 83 RTE A 1 General Information 92077 90006 2 82 1 83 RTE A 1 Programmer s Reference Manual 92077 90007 6 83 1 12 83 RTE A 1 File Management Reference Manual 92077 90008 2 82 1 7 82 RTE A 1 LINK Relocating Loader Manual 92077 90009 7 82 1 1 83 RTE A 1 Debug Reference Manual 92077 90010 2 82 RTE A 1 Driver Reference Manual 92077 90011 6 83 1 12 83 RTE A 1 System Design Manual 92077 90013 6 83 RTE A 1 Generation Planning Guide 92077 90014 2 82 4 1 83 RTE A 1 Generator Reference Manual 92077 90016 2 82 RTE A 1 Software Installation Guide 92077 90018 2 82 4 1 83 RTE A 1 Driver Designer s Manual 92077 90019 6 83 RTE A 1 Quick Reference Guide 92077 90020 6 83 RTE A 1 Generation Req for Drivers 92077 90021 2 82 1 1 83 RTE A 1 System Gen amp Installation Man 92077 90034 98 83 2 12 83 1 LINK User s Manual 92077 90035 6 83 RTE A 1 Index amp Glossary 92077 90036 6 83 RTE A 1 Relocatable Librari
27. Record 9 2 PRE AMPS 2 ASCII character string relative to magnetic North coil set 1 or 2 in metres in metres in ohms in ohms No of next MTnnnn file No of freq band No of files in each freq No of points collected Digital interval in msec 7 frequency band counts band array 1 5 Ex Ey Hz Hx Hy gain switch settings 1 to 7 array 1 3 Ex Ey Ez Ez unused filter settings not used array 1 3 Ex Ey Ez Ez unused gain settings 1 to 3 array 1 3 Hz Hx Hy filter settings not used array 1 3 Hz Hx Hy gain switch settings 1 to 3 array 1 2 LP filter HP filter filter switch settings 1 to 7 array 1 2 E preamps H preamps 1 old preamps 2 new preamps 9 gt 30 4 5 3 PROGRAM UPDAT UPDAT allows the user to update the contents of MTANS MTANS contains data that will be used as input to the data acquisiton routine Most of the data on this file ends up on the data file header MTANS can be veiwed quickly using the ST command in MAGTL UPDAT is scheduled in MAGTL by typing UP Fields AZIMUTH NEXT FILE No No POINTS DIG INTERVAL and PRE AMPS are all prompted for via one of the subroutines READI READR or READM The fields FREQ BAND POSTAMP GAINS FILTER PASSES are taken from the switch positions read off the multiplexer and decoded using the assembler subroutines DECOD or DECID 4 5 4 SUBROUTINE READI OLD DATA READI is a subroutine called by program UPD
28. SPO 1 Programmable oscillator 32 XDM 1 Multiplexer 45 9p FIG 1 MT SYSTEM BLOCK DIAGRAM HP POWER SUPPLY POST AMP PROGRAMMABLE POWER SUPPLY o e gt tO H FLITE TRONICS INVERTER OSCILLATOR BMR 115V AC 50Hz SET OF 3 MAGNETIC INDUCTION COILS MAGNETIC PRE AMPS HP1000 POST AMPS PHOENIX PHOENIX amp FILTERS A D INTERFACE 600 CONVERTER CPU BMR 2 PAIRS ELECTRIC PRE AMPS H TEST SIGNAL 5 CALIBRATOR CRO MUX BMR PRINTER 2623 GENERATOR 27 W 18 HP7908A DISC amp MAG TAPE DRIVE Magnetic induction coils Cd CdCl pots Signal generator Magnetic Preamplifiers Electric Preamplifiers Calibrator Postamplifier power supply Postamplifiers and filters 0 Phoenix A to D converter Phoenix interface Programmable oscillator HP 1000 600 CPU VDU and printer Disc and mag tape drive FIG 1 KEY Geotronics model MTC 4SS Geotronics model MTE 2 Hewlett Packard model 3300A Geotronics model MTH 4 Geotronics model MTE 4 Geotronics model MTE 4 BMR construction BMR design and construction Tektronix model 5113 Phoenix model 6915 3754 Phoenix model PDI Std Interface BMR design and construction Hewlett Packard model A600 Hewlett Packard model 2623 Hewlett Packard model 7908A 47 SU FIG 2 MT SYSTEM RACK POSITIONS POST AMP POWER SUPPLY POST AMPS
29. TINE DECID ICODE IARRAY This subroutine will decode a 16 bit word ICODE read off the XDM 1 multiplexer and put values into a 5 word integer array IARRAY according to the following scheme bits 0 to 2 into word 1 of IARRAY 3 5 n 2 n n D 0 S t amp 6 8 2 gain filter 0711 4 Ysettings n 1 u 1 4 n n 5 D Data the array is all right justified FORMAL PARAMETERS ICODE input data from the MUX IARRAY decoded output DECID is called as follows DIMENSION IARRAY 5 CALL EXEC 1 100032B ICODE 1 READ FROM MUX CALL DECID ICODE IARRAY INTO 1CODE 4 5 8 SUBROUTINE DECODE ICODE IARRAY This subroutine will decode a 16 bit word ICODE read off the XDM 1 multiplexer and put values into a 6 word integer array IARRAY according to the following scheme bits 0 amp 1 into word 1 of IARRAY E H preamp P ge o SU EE Nu i gain settings 4 5 n H 3 6to8 4 E H preamp 9 11 Bom filter settings H 12 14 6 Data the array is all right justified 22 FORMAL PARAMETERS ICODE input data from the MUX ARRAY decoded output DECODE is called as follows DIMENSION IARRAY 6 CALL EXEC 1 100032B ICODE 1 READ FROM MUX CALL DECODE ICODE INTO ICODE 32 Ce 4 5 9 PROGRAM AQUIR AQUIR is scheduled by MAGTL to collect 5 channels of MT data The data on each channel is as follows Channel 1 Ex Data induce
30. These conditions occur most of the time in sedimentary basins in Australia but it has been found on some occasions that plane wave conditions do not occur and this complicates the processing of the data When plane electromagnetic waves strike the earth s surface they may do so at an angle they are then partially reflected at an angle equal to the angle of incidence and partially refracted at the air ground interface The angle of refraction depends on the angle of incidence of the wave and the relative velocity of the wave in the air and earth typically this velocity ratio will be many orders of magnitude so the refracted wave will always be propagated nearly vertically downwards into the earth At the point of reflection on the earth s surface the reflected magnetic component of the wave is in phase with the incident component while the electric field undergoes cancellation due to phase reversal The magnetic field at the air earth interface is therefore nearly twice its value in free space but the electric field component is reduced by many orders of magnitude over its free space value and may be ignored VN The MT technique relies on this vertically propagated alternating magnetic field and the measurement of currents induced in a conducting medium the earth by that field Penetration of the wave is determined by its frequency of oscillation and the conductivity of the medium which together cause energy loss due to eddy currents
31. al for more details External clocking of the Phoenix is provided by the 5 0 1 Programmable oscillator 10557 is used when data acquisition is in progress 24 Lk ID 57 uses the following entry points into the Device Table DVT DVT ENTRY POINT USAGE ENTRY POINT UPON ENTRY TO 10 57 UPON EXIT DVT15 contains EXEC request not used to select random sequential output amp internal external clock modes for the Phoenix DVT16 contains EXEC buffer contains address error code DVT17 contains EXEC buffer contains trans length mission log DVT18 contains optional Phoenix start and end channel not used address in lower and upper bytes respectivly DVT19 not used optional contains neg count The subfunction in DVT15 can have the following values OB Puts Phoenix in Random output External clock mode 1B Puts Phoenix in Sequential output External clock mode 2B Puts Phoenix in Random output Internal clock mode 3B Puts Phoenix in Sequential output Internal clock mode In addition ID 57 uses the following entry points into the Interface Table IF5 pointer to address of active DVT IF6 pointer to IFT status 15 25 4 4 2 ID 62 XDM 1 MUX INTERFACE DRIVER ID 62 handles I O to the multiplexer on LU 32 NOTE that for historical reasons some wiring has been done back to front on this equipment so the bit order of the incoming data from the filter switches has to be reversed in this driver ID
32. ape and HP data cartridge format ii It will be necessary to design and construct pre preamplifiers for the three magnetic channels These would be located at the sensing coils and provide sufficient gain for the inputs of the BMR preamplifiers iii The BMR constructed preamplifiers were not field tested prior to the system being dismantled iv transfer function for the complete system would have to be determined as the present poles and zeros information is not valid for the revised equipment Software for data acquisition and interfacing cables are available for this replacement equipment 12 4 MAGNETOTELLURIC DATA ACQUISITION SYSTEM SOFTWARE 4 1 INTRODUCTION 4 1 1 OVERVIEW This chapter describes the magnetotelluric data acquisition system software MT DAS which used the HP RTE A 1 operating system in an HP A600 computer with a 2623A graphics terminal and 7908A disc and cartridge tape unit The software was written during the first quarter of 1984 at the BMR and updated in early 1985 with the replacement of the Geotronics preamplifiers This software supercedes that which ran on the old HP E series computer It has an enhanced user interface program MAGTL in addition to having a simplified program structure modular programs written in FORTRAN 77 and rationalised data file structure i e no duplication of data items within data files along with the use of files with variable length records In addition to t
33. ce and then determines what percentage of the total cartridge was used for the scratch file The scratch file is then purged 4 5 13 PROGRAM FILES FILES displays the number of files collected so far in each of the 7 frequency bands collected by the MT DAS by typing FI This information is kept on the MT answer file MTANS in record 2 words 14 to 20 i e word for each channel 35 LS 5 BIBLIOGRAPHY OF BMR MT PUBLICATIONS BARTON T 1986 Broken Hill magnetotelluric survey 1984 Operational report Bureau of Mineral Resources Geology and Geophysics Australia Record 1986 4 CULL J P 1982 Magnetotelluric profiles in the McArthur Basin BMR Journal of Australian Geology and Geophysics Vol 7 No 4 275 286 CULL J amp SPENCE A G 1985 Magnetotelluric soundings across the boundary of the Precambrian Willyama complex and the Cainozoic Murray Basin southeastern Australia Bureau of Mineral Resources Geology and Geophysics Australia Report No 250 CULL J SPENCE A G MAJOR J A KERR D W amp PLUMB K A 1981 1978 McArthur Basin magnetotelluric survey Bureau of Mineral Resources Geology and Geophysics Australia Record 1981 1 CULL J SPENCE A G amp PLUMB K A 1981 The 1979 McArthur Basin magnetotelluric survey Bureau of Mineral Resources Geology and Geophysics Australia Record 1981 64 DEVENISH A B 1979 Sixteen channel digital multiplexer type XDM 1 Bureau of Mineral Resources Geo
34. d telluric current in x plane Channel 2 Ey Data S S 1 j Channel 3 Hz Data time varying magnetic signal in z plane Channel 4 Hx Data i UD MES Channel 5 Hy Data 7 n y NOTE Ez data in the vertical plane is not collected AQUIR uses 3 files MTANS 18 which must already exist the actual data file MTnnnn where nnnn is a unique file number and MTSTAT which holds status information MTANS contains data that will be used as input to this program IL contains the site information switch settings etc MTnnn has a header record copied directly from the MTANS file the gains poles amp zeros records for each channel and the collected data MTANS is written to at the beginning and end of each data acquisition AQUIR operates in the following manner 1 open 5 terminate if error ii create MTnnnn nnnn is NEXT FILE No of MTANS 111 set up MTnnnn file header using data in MTANS record 1 call subroutine GAINS to select poles zeros amp gains v set up status file record amp output it to MTSTAT vi write out the above values for 5 channels records 2 amp 3 vii start the Phoenix A to D Converter and collect the specified number of files and samples at the given sampling rate viii output status file record when acquisition is completed 33 Size MTHDR words offset 27 1 28 29 30 31 32 34 36 37 PO CO O
35. defaulted A Y scale factor of 20000 is usually adequate for all channels of MT data A smaller Y scale will cause the displayed data to be magnified in amplitude useful if the recorded signals are very weak The X factor will stretch the X scale by the specified factor A starting point other than the first bit of data may also be specified The file name header and plot of data is written on the screen which can then be hard copied using the graph copy key on the terminal 21 x 44 4 3 4 FFT FFT is a fast fourier transform program based upon program FFOUR as described by Spence amp Kerr 1982 to process raw MT data files MInnnn into fourier transform files FTnnnn FFT should be run under CMND No indication is given when it stops When running FFT a start file number nnnn and the number of files to process mm must be specified e g CMND RU FFT 0250 50 This will create files FT0250 to FT0299 from the raw data files 0250 to 0299 The original MT data files are retained after this operation When processing MT files acquired prior to 1985 the old version of FFT 1 should be used as the structure of the MI file was changed 1985 to accommodate data collected by the BMR preamplifiers 4 3 5 TENSE TENSE is a program which carries out the tensor analysis of the data It is based on program TENSR as given by Spence amp Kerr 1982 TENSE should be run in FMGR TENSE will indicate on the VDU eac
36. e DL 24 list all files on tape Selected files on tape may also be transferred to a cartridge using the FC command CO 24 namr cr 4 2 8 FMGR 005 ERRORS These occur when a file has been corrupted e g due to filling up a cartridge usually file ROTTEN 50 18 This is remedied by purging the corrupt file and any other unwanted files on the cartridge do a DL cr HP packing the cartridge and trying again If there is still not enough room then move files from this cartridge onto another using the procedure file MOVE This will prompt for the from cartridge security code the to cartridge and the files to move The user must precede the above answers with a and terminate this procedure file with a E 4 2 9 FMGR 019 ERRORS These occur when running a program or a procedure file They are caused because the program involved has not been linked for the current operating system It is corrected by re linking the program under the current operating system see the LINK manual L 18 4 2 10 FMGR 033 ERRORS No room on cartridge 19 This is remedied by examining the contents of cartridge 19 using DL 19 there are only Minnnn files on CR 19 then either sufficient data for the current site has been acquired the previous sites MInnnn files have not been archived onto tape If there are any other files files on CR 19 e g NEWDAT they should be moved onto either CR 16 or 17 or purged if not wanted
37. e number of files on cartridge 19 and ensure that there is sufficient room for subsequent data acquisition Several utilities exist to assist the user to do this They are outlined in the next section The ST command in MAGTL can be used to determine how full data cartridge 19 is It is displayed as a blinking percentage in the top right hand corner of the screen The first file acquired should always be checked to determine whether all wires have been connected properly 4 2 7 DATA ARCHIVAL AND RETRIEVAL For archival onto magnetic tape LU 24 the following commands are used PUDATA Archives FTnnnn MInnnn ROT and MTSTAT files onto tape using PURGE subroutine These files reside on cartridge 17 UPDATA Recovers files from tape using RTREVE subroutine STDATA Recovers all data files from tape using RECOVR subroutine These procedure files reside on cartridge 16 but if these are to be used for data files residing on cartridge 16 then STDATA and RECOVR should be moved to cartridge 20 and purged from 16 so as to avoid a cartridge lock out error 17 This may be done as follows Copy files to another cartridge CO namr source cr dest cr Purge the file from the source cartridge PU namr sec code cr Or if desired instead of purging the file may be renamed by RN old namr sec code cr new namr Other useful commands for tape handling are the File Copy FC commands LH 24 list tape header LC 24 list comment fil
38. er 1 can 11 To 10 To 7 6 To 5 4 To 3 To 2 To fo 0 To To 2 3 To 4 5 6 To 7 To 10 To 1 12 To 13 14 15 To 16 To i e the select select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an select an frequency output output output output output output output output output output output output output output output output output output output output output output output output frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency frequency n kHz 2 where of of of of of of of of of of of of of of 512 256 128 64 32 16 31 OD CH rm GA sl have the following octal values 9 25 625 8125 90625 953125 976563 488281 244141 122070 061035 the frequency defined by parameter 1 n the parameter value e g in FMGR to select an output frequency of 125 Hz do CN 31 25B8 3 28 b 4 5 DATA ACQUISITION SYSTEM SOFTWARE COMPON
39. es Ref Man 92077 90037 12 83 1 Primary System Software Install 92077 90038 3 84 RTE A 1 FCO Utilty Manual 92077 90048 12 83 FORTRAN 77 Reference Manual 92836 90001 12 81 1 4 82 Graphics 1000 Reference Manual 92841 90001 1 83 7 83 39 The following is a list of manuals which relate to the computing equipment as used for the magnetotelluric data acquistion system The print date shown YL APPENDIX 2 POLES amp ZEROS FILES FILE P8722 17 4 Ex Channel Preamps 3100 S Ex channel preamps No poles No fudgp s 70 07 70 07 186 605 0 0 13 40 0 0 poles 2 5005E7 fudgp no zeros no fudgz s 0 01647 0 004934 0 01196 0 01510 1 09685E 7 postamp 0 04528 0 01356 0 0329 0 04156 6 27717 6 0 01647 0 04934 0 1196 0 1511 1 09777 3 0 7547 0 2258 0 5483 0 69248 0 484135 3 4298 1 0270 2 4924 3 1481 206 664 17 157 5 1359 12 469 15 739 1 2925 5 54 893 16 441 39 868 50 365 103548 7 7 071 4 0 0 7 071 4 0 0 1 0 postamp 7 071E 3 0 0 7 071 3 0 0 1 0 j 2 1214E 3 0 0 2 1214 3 0 0 1 0 7 071 2 0 0 7 071 2 0 0 1 0 0 3536 0 0 0 3536 0 0 1 0 1 7678 0 0 1 7678 0 0 1 0 7 07 0 0 7 071 0 0 1 0 0 0 0 0 0 0 0 0 1 0 postamp Ey Channel Preamps 3100 Ex channel preamps No poles No fudgp s 70 07 70 ud 186 605 0 0 13 40 0 0 poles 2 5005E7 fudgp no zeros no fudgz s 0 0
40. es dee kas 36 lee 38 APPENDICES Appendix 1 Hewlett Packard 15 39 Appendix 2 Poles and zeros for preamplifiers 40 Appendix 3 MT system boot file 43 Appendix 4 Development system boot file 44 Appendix 5 Logical unit LU table 45 FIGURES Figure 1 MT system block diagram 46 Figure2 system rack positions 48 SUMMARY This record describes the Bureau of Mineral Resources BMR magnetotelluric MT data acquisition system DAS as used in field operations during 1984 This document will assist in the rebuilding of this system should a requirement arise for further BMR MT surveys It was considered important to document the system and software that was operating in 1984 following the outcome of review into the BMR MT program The review examined staff movements which had resulted in a loss of expertise in this field and the suitability of this method to the BMR s present scientific programs Subsequently the BMR MT program was suspended 1 INTRODUCTION The data acquisition and processing system used by BMR for MT investigations has evolved over a number of years This document has been written to assist in the rebuilding of the system should it be required for use at some future time Included
41. eset by an adjacent push button Two paralell connected outputs are provided for each amplifier one for connection to the postamplifier and one for signal monitoring Input connections are as per the sensor coils The transfer functions for coil and preamplifier combinations are given by Word amp Hopkins 1971 3 2 3 E FIELD SENSOR ELECTRODE Type Geotronics Model MTE 2 BMR vocab no 015 The 2 is a cadmium cadmium chloride Cd CdCl buffered type electrode The electrode wire lead is connected to a cadmium rod This should be bound with Scotch 23 tape or similar to seal against moisture which can cause electrolysis to occur between the copper lead wire and the Cd rod subsequently causing signal degradation The Cd rod is immersed in a saturated solution of CdCla H20 which makes ultimate contact with the ground through porous ceramic pot Caution should be exercised in the handling of this solution as it is toxic Each electrode is placed in a hole about 40 cm in diameter and about 50 cm deep Water is added to form a slurry to ensure a good porous pot to ground electrical contact This arrangement is covered with a plastic bucket to prevent rapid drying of the contact area The electrodes are checked on a daily basis and re watered if required 3 2 4 E FIELD PREAMPLIFIER Type Geotronics Model MTE 4 S No 4E 003 Number of channels 3 two used one spare Connectors Input 2 binding posts blue whi
42. esigned and constructed preamplifiers and postamplifiers 3 2 7 MT E amp H POSTAMPLIFIERS AND FILTERS Type BMR MTA 1 S No s 1 2 3 4 5 6 Number of channels 5 Connectors Input BNC floating Output BNC single ended Power Cannon 14 P 5P Gain steps 3 10 30 100 300 1000 3000 High pass filter 0 001 0 01 0 03 0 1 0 5 2 5 10 Hz 3 dB points Low pass filter 0 012 0 033 0 12 0 55 2 5 12 5 40 Hz 3 dB points Noise 1 uV pp rti 0 001 40 Hz Output voltage 41 2 V on recorder output terminal 12 V on CPU output terminal Input impedance 10 kohm External Power requirements 15 V DC 400 mA max Internal Power requirements 12 V DC 5 V DC Operating temp 0 C to 50 C BMR vocab no MMA 030 The MTA 1 postamplifier accepts outputs from the E and H preamplifiers It performs bandwidth shaping and amplification The output analogue signal is interfaced to the Phoenix analogue to digital converter and monitoring devices Gain settings on all five channels are independent of each other but they may be controlled by the CPU High and low pass filter settings are slaved from channel 1 or may be controlled by the CPU Logic controls for all five channels of filter and gain settings are sent via the digital multiplexer to the CPU for data logging A complete description of the MT postamplifiers is given by Lui 1983 I 3 2 8 SIXTEEN CHANNEL DIGITAL MULTIPLEXER Type BMR XDM 1 5
43. for use with Multiplexer port 6 Select code 1 to 8 00 0 00 Phoenix interface port 7 Select code 1 to 8 00 0 0 Programmable oscillator port 8 Select code 1 to 8 Note R6 to R11 are removed to match ground true logic of the SPO 1 oscillator 3 2 13 DISC AND TAPE DRIVE Type Hewlett Packard Model 7908A S No 2208A00890 Power requirements 240 V AC 50 Hz BMR vocab no XDC DD12 The 7908 contains five disc cartridges CR 16 to 20 for data storage acquisition software and system control The unit includes a cartridge type tape drive for data archival and system back up use For data archival 150 foot HP data cartridge tapes were used 3 2 14 COMPUTER TERMINAL Type Hewlett Packard Model 2623A opt 015 050 262 S No 2226V19232 Power requirements 240 V AC 50 Hz BMR vocab no XDC DT11 The 2623A is used for interactive control of data acquisition and processing It includes a graphics capability and a thermal printer which allows hardcopy plots of processed data to be produced in the field NN 3 3 SYSTEM RECONFIGURATION The BMR MT data acquisition system was decommissioned during 1985 With the exception of the HP A600 computer system and the Phoenix equipment all components were placed in storage Should this system be required the following points may be of assistance 1 All software is written under the RTE A 1 operating system and is archived on HP1000 9 track t
44. h FTnnnn file as it accesses it When running TENSE a start file number nnnn number of files to process mn and a processing parameter in octal must be specified e g RU TENSE nnnn mm 4540B Produces rotated tensor analysis with no ROTTEN file produced RU TENSE nnnn mm 4050B Requires an input rotation angle and produces a ROTTEN file RU TENSE nnnn mm 4040B Calculates rotation angles and uses them to produce a ROTTEN file 4 3 6 MTPLT MTPLT is a program which produces plots of apparent resistivity in ohm m vs period in sec phase angle in degrees vs period sec and rotation angle degrees vs period sec It uses a rotated tensor analysis ROTTEN file produced by TENSE as its input TENSE is based on programs MTPLR MTPLP and MTPLA as given by Moore 1976 The plots are displayed on the VDU and a hard copy may be obtained using the graph copy key on the terminal These are examined in the field to assess data quality and later to assist in the screening and averaging of the data An example of running the program is given below 22 FMGR RU MIPLT OPTIONS 1 RHO 2 PHASE 3 ROTATIONS ve for points 1 OPTIONS 1 ROUTINE 2 VARIATIONS 2 NPD TCENTRE COHLIM 2 SKEWLIM 2 10 1 0 7 0 8 1 0 0 5 ERROR BARS O NONE 1 ST DEVIATION 2 ST ERROR NAME OF INPUT FILE ROTTEN The above example would produce XY and YX plots of resistivity vs period with standard deviation error bars The VARIAT
45. he MT DAS programs there are several utilities which facilitate file manipulation archiving and purging as well as a help file an answer file a status file and of course the data files All system software is archived on HP data cartridge and 9 track magnetic tape formats Data processing software is given by Moore 1976 1977 and Spence amp Kerr 1982 4 1 2 DATA FILES There are three types of data files Minnnn files Data files made by MAGTL on disc cartridge 19 Flnnnn files Fourier transform files made from MTnnnn files by program FFT They are usually on disc cartridge 20 but can be on 16 and 17 as well They have a security code of 50 Tense files These are the tensor rotation files ROTTEN and TIPPER They are made by program TENSE from FTnnnn files They normally reside on cartridge 18 and have a security code of 50 The different input output 1 0 system of the A series CPU necessitated writing new interface drivers for the Phoenix analogue to digital converter the 5 0 1 programmable oscillator and the XDM 1 multiplexer Ali of the above components of the MT DAS are described in the following sections I3 4 2 USERS GUIDE 4 2 1 SYSTEM INITIALISATION After powering up all hardware components the MT DAS system is booted up by typing BDC0027BCF01 or BDC0027 for the development system and pressing carriage return After the system has been booted up the time must be set with the FMGR TM comma
46. in this document are brief descriptions of the system components and details of the data acquisition software 11 software was written using the Hewlett Packard RTE A 1 operating system and supercedes that previously given by Cull amp others 1981 and Spence amp Kerr 1982 A bibliography of BMR MT related publications is also included The MT system may be conviently divided into four parts data acquisition data processing data manipulation and data interpretation This paper deals with the equipment and software for the first two of these 2 THE MAGNETOTELLURIC METHOD The MT method is a geophysical tool for mapping subsurface electrical conductivity Observations are made of the natural transient magnetic field together with the induced electric field A detailed description of the method is given by Vozoff 1972 The MT technique depends on electromagnetic energy reaching the earth s surface from two major sources Signals with a frequency of less than about Hz are usually due to ionspheric currents at heights of 75 km or greater Frequencies about 1 Hz and greater are usually produced by electrical or thunderstorm activity in the atmosphere It is assumed in the MT method that these sources are remote calculations are based on the assumption of plane waves but adequate results can be obtained using curved waves with a radius of curvature greater than several times the skin depth of penetration of the earth at that frequency
47. logy and Geophysics Australia Record 1979 48 KERR D W 1977 Overseas visit to India for magnetotellurics Bureau of Mineral Resources Geology and Geophysics Australia Record 1977 23 LIU Y S B 1983 Magnetotelluric signal amplification and filtering a novel design Bureau of Mineral Resources Geology and Geophysics Australia Record 1983 8 MOORE R F 1976 Graphic presentation of magnetotelluric data Bureau of Mineral Resources Geology and Geophysics Australia Record 1976 97 MOORE R F 1977 Screening and averaging magnetotelluric data prior to one dimensional inversion Bureau of Mineral Resources Geology and Geophysics Australia Record 1977 8 MOORE R F KERR D W VOZOFF K amp JUPP D L B 1977 Southern Cooper Basin magnetotelluric survey South Australia 1974 Bureau of Mineral Resources Geology and Geophysics Australia Record 1977 41 POLLARD P C 1971 Computer program for producing magnetotelluric curves for a horizontally layered earth Bureau of Mineral Resources Geology and Geophysics Australia Record 1971 35 SPENCE A G 1982 Central Eromanga Basin magnetotelluric survey 1980 Operational report Bureau of Mineral Resources Geology and Geophysics Australia Record 1982 34 SPENCE A G amp KERR D W 1982 magnetotelluric system software 1980 Bureau of Mineral Resources Geology and Geophysics Australia Record 1982 35 M T Broken Hill Block Bureau of Mineral Resources Australia
48. nd e g TM hrs min sec month date year At the start of each new site the following action must be taken 1 Transfer control to procedure file PUDATA to archive and purge all data files from the previous site 2 Run MAGTL and type IN to initialise the answer file 3 Type UP to update the answer file The MT DAS system is then ready to use User interface to the system is obtained by running program MAGTL the main control routine in FMGR e g RU MAGTL MAGTL will clear the screen write out a heading that includes the current version number and issue a prompt for a command input e g MAGTL MT Data Acquisition System lt 861204 1423 gt Type HE for help EX to exit The valid inputs to MAGTL are AB to abort data acquisition immediately and purge data file AQ to start data acquisition BR to break abort data acquisition at next file CU to display the current answer file EN to end MAGTL and disable printer if il was enabled EX to exit from MAGTL leaving printer status unaltered FI to display the number of files collected in each frequency band HE to display the MT help file IN to initialise the MT answer file RE to enable the printer for hard copy reports RX to disable the printer ST to display the MT survey status file UP to update the MT answer file 14 IF MAGTL cannot recognize a command input e g CC it will respond in the following manner MAGTL
49. ns trans length 1 number of mission log channel to read defaull is 1 DVT18 contains optional selection parameter default 0 In addition ID 62 uses the following entry points into the Interface Table IFT IF5 pointer to address of active DVT IF6 pointer to IFT status 4 4 3 10 70 5 0 1 PROGRAMMABLE OSCILLATOR DRIVER ID 70 controls the programmable oscillator It outputs a function code to LU 31 which determines the oscillator frequency FMGR command CN can be used to control LU 31 via ID 70 CN 31 25B 3 Starts the oscillator at a frequency corresponding to 3 CN 31 does a reset CN 31 25B 20 will stop the oscillator ID 70 is the RTE A interface driver used with the SPO 1 Programable Oscillator and a Parallel Interface Card PIC Control EXEC request only are allowed Read and write requests are rejected with the appropriate error code set The following error codes are returned in the A register 0 No error 1 Illegal request read or write 3 SPO 1 timed out 27 ID 70 uses the following entry points into the Device Table DVT DVT ENTRY POINT USAGE ENTRY POINT DVT15 DVT16 UPON ENTRY TO ID 70 contains EXEC request code amp function contains frequency selection code UPON EXIT not used contains error code The subfunction in DVT15 can have the following values to issue clear request to register 32 to reset PIC 25b to Paramet
50. ps A listing of each of these files is given in Appendix 2 This feature is only temporary and can be easily removed by only allowing for one data file i e P amp Z22 for the new preamps 34 aL Poles amp Zeros record PoZ BUF for each channel is written to the MTnnnn file POLES g ZEROS FILE FORMAT PoZ BUFF Size Name offset words 2 GAIN total gain for this channel 3 2 FUDG P gain normalisation for the poles 5 2 FUDG Z gain normalisation for the zeros 7 1 NO P No of poles 8 NO Z No of zeros 9 l IDIST wire length E channels only 10 1 LX No of points 11 2 DELTA digitising interval in msec 13 120 POLES 30 up to 30 poles 133 120 ZEROS 30 up to 30 zeros 256 total The above record is copied to the FT file by the FFT program but is split into two 128 word records 4 5 11 PROGRAM HELP The function of program HELP is to display on the system console the contents of the MT Help file called MTHLP 18 HELP cannot locate the MT Help file it will say so HELP can be scheduled from FMGR or MAGTL by typing HE Control returns to MAGTL when HELP finishes 4 5 12 PROGRAM STATS STATS displays the MT DAS status on the terminal by typing ST MT survey status records are written onto a file called MTSTAT 18 STATS merely reads this file and writes it out STATS also reports on the Zfull of the data cartridge It does this by temporarily creating a scratch file on the data cartridge to use all the unused spa
51. s Azimuth deg Coil Set used Ex Separation m Ey Separation m Rx Resistance ohms Ry Resistance ohms Effective Ex Separation automatically calculated Effective Ey Separation automatically calculated Next File Freq Band No of Samples Dig int msecs Files in band Post Amp Gains E Preamp Filters E Preamp Gains H Preamp Filters H Preamp Gains Low amp High Pass Filter Bands 15 4 2 4 DATA ACQUISITION Additional input is required after the AQ and UP commands After the AQ command MAGTL will ask for the number of data files to be collected the example below two files are collected according to the information contained in the answer file MAGTL Acquire how many files Doc 2 Data Acquisiton Started for 2 Files MAGTL 4 2 5 ACQUISITION MONITORING Once data acquisition has started control returns to MAGTL and other commands can be entered The answer file cannot be updated during an acquisition because the acquisition uses data from it Hence if the CU or UP commands are entered their only action is to respond with DATA ACQUISITION IN PROGRESS NO ACCESS TO MTANS Note also that the AQ command must not be entered again until after the current acquisition has finished If AQ is accidently input to MAGTL the user must ask for zero files and control will return to MAGTL without requesting an acquisition to start After each file has been acquired a message is written on the sta
52. sted Should they be required it will be necessary to include an additional fixed gain field preamplifier situated with the magnetic sensor coils to increase the signal level to the recording cab It will be necessary to determine the transfer functions for the magnetic and electric channels for the system under field conditions This would allow the poles and zeros of the system to be calculated and included into the data acquisition software Design specifications required for the H field pre preamplifiers are given below Number of channels 3 Gain 100 fixed Filter 0 100 Hz fixed bandwidth Input impedance 1 45 kohm 10 uf Common mode rejection 120 dB typical Internal power 6V DC batteries Max noise 0 20 uV pp rti 0 002 25 Hz Sensitivity 22 0 05 V gamma approx when combined with the 455 coil 10 3 2 12 CPU Type Hewlett Packard A600 Series 1000 Model 2156A opt 015 5 2309A00319 Power requirements 240 V 50 Hz BMR vocab no XDC DC30 The CPU included the following cards 2 x HP5180 A600 memory control PROM card ports 1 amp 2 1 x HP12101 A600 PROM processor card port 3 1 x HP12005A A Asyncronous serial interface card for use with HP2623A VDU port 4 Select codes Ul 1 to 8 U21 1 TO 8 0000 0 1 x HP12009A HP IB interface card for use with HP7908A Disc Drive port 5 Select code 1 to 8 0 0 000 3 x HP12006A Parallel interface card
53. sts of collecting data over specific frequency bands These bands were selected on the basis of dynamic range and economy in the number of data points collected The frequency bands digitising interval and number of data points collected are given in Table 1 These factors determine the maximum bandwidth that may be recorded site is normally occupied for a period of two days during which time up to 160 data files would be recorded onto disc The recorded data are usually processed to the stage of producing a plot of period versus apparent resistivity to ensure that sufficient data of good quality have been collected before vacating the site TABLE 1 FREQUENCY BANDS AND SAMPLING RATES FREQUENCY BAND NO POINTS DIGITISING INT TYPICAL NO PER FILE OF FILES Hz msec COLLECTED 0 001 0 012 2048 4096 10 0 01 0 033 1024 2048 10 0 03 0 12 1024 1024 10 0 1 0 55 1024 256 25 0 5 2 5 1024 64 35 2 5 12 5 1024 8 35 x 10 0 40 0 1024 4 35 3 2 HARDWARE This section contains brief information on each component used in the BMR MI system A block diagram of the equipment used in the 1984 survey Barton 1986 is shown in Fig 1 and their rack positions in Fig 2 The following information is included in this document as an aid for rebuilding the system should a requirement arise for future BMR MT investigations 3 2 1 H FIELD SENSOR COILS Geotronics Model MTC 4SS S No s 1005 1006 1007 1014 1015 1016 overall length 204
54. te Input guard shield yellow post Signal common black post Output 2 paralell BNC connectors Gain steps 10 100 1000 Filter 4 pole 4 zero band reject filter with notch centred on 50 Hz Noise 3 0 uV pp rti 0 002 25 Hz Chopper frequency 2 KHz Input voltage undistorted 48 V abs max Output voltage 5 V max Input impedance gt 100 kohm Common mode rejection 100 dB at 1 Hz 86 dB at 20 Hz 74 dB at 200 Hz 60 dB at 2 kHz Power requirements 115 V AC 50 Hz 25 W max Operating temp 0 C to 50 C BMR vocab no MMA 020 The E preamplifier is essentially the same as the H preamplifier The input electrode connections are shown below ELECTRODE AMPLIFIER CHANNEL TERMINAL Ex north 1 south 1 GREEN Ey east 2 YELLOW Ey west 2 BLACK The guard shield and the signal ground are left floating O 3 2 5 MT CALIBRATOR AND POWER MONITOR Type Geotronics Model 2 S No 2C 001 Hewlett Packard function generator Model 3300A S No 939 05086 Power requirements 115 V AC amp 240 V AC 50 Hz BMR vocab no MMC 080 The MTC 2 is a system service unit that provides calibration voltages for the preamplifier inputs monitors the AC line voltage and frequency and serves as an auxilary DC power supply 3 2 6 MT POSTAMPLIFIER POWER SUPPLY Type BMR MTA 1 Power requirements 240 V AC 50 Hz BMR vocab no MMP 055 The MTA 1 provides 4 15 V DC for the BMR d
55. tus file MTSTAT saying what file was acquired and when it was completed A message is output to the VDU saying how many files were recorded when an acquisition is finished e g ACQUISITION COMPLETE FOR 2 FILES It can be determined whether data acquisition is currently in progress by one of several means 1 Observe the Phoenix A to D converter the lights flash during data acquisition 2 Enter CU or UP these commands will indicate if acquisition is in progress 3 In FMGR enter PL and observe if program AQUIR is doing I O to LU 30 the Phoenix 4 Type ST in MAGTL and check whether the last data file has been completed 16 4 4 2 6 TROUBLE SHOOTING If the MT DAS system cannot access any of the files it uses it will report the appropriate FMGR error code If any errors are reported they should be investigated before re running MAGTL The following files are used by MAGTL and must exist MTANS 18 the answer file MTSTAT 18 the status file MTHELP LA 18 the help file In addition to the above MAGTL uses a temporary scratch file on disc cartridge 19 called NEWDAT This file should only exist during actual data acquisition and should only be opened to program AQUIR After ACQUISITION COMPLETE FOR n FILES it will be purged If the A to D converter fails to stop on completion of the file acquisitions down DN 31 then up UP 31 the programmable oscillator 5 0 1 It is the users responsibility to manage th
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