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The only difference between the standard and SX version is the sensitivity is 4pT/rt-Hz and 20 pT/rt-Hz respectively. Here is an expected response with the magnetometer moving past a generic magnetic projectile: In this case the amplitude is about 1nT in total from peak to peak. The feature itself is quite distinguishable. This is assuming there is no noise in the System. Here is what the data looks like with 4pT/rt-Hz noise: You can see the general structure is still there but there is a little more wiggle on the trace that is associated with the noise of the System. Here is the data with 20 pT/rt-Hz noise: Again, here the structure is clearly visible but the data looks a bit noisier. With some signal processing technique, such as low pass filtering, noises can be further reduced. Please note that in real surveys, detecting 1nT peak-peak anomalies is always a big challenge even with the most sensitive magnetometers due to other noise sources, such as motion noises and environmental noises. Therefore, SX version is in general NOT the limiting factor for conducting surveys. To understand this concept better, you can use the magnetic gradient tool developed by our partner in the UK, Geomatrix Earth Science.

The only difference between the standard and SX version is the sensitivity is 4pT/rt-Hz and 20 pT/rt-Hz respectively. Here is an expected response with the magnetometer moving past a generic magnetic projectile: In this case the amplitude is about 2nT in total from peak to peak. The feature itself is quite distinguishable. This is assuming there is no noise in the System. Here is what the data looks like with 4pT/rt-Hz noise: You can see the general structure is still there but there is a little more wiggle on the trace that is associated with the noise of the System. Here is the data with 20 pT/rt-Hz noise: Again, here the structure is generally there but the data looks quite a bit noisier. So for smaller targets or more subtle anomalies they can be obscured or missed entirely. To understand this concept better, you can use the magnetic gradient tool developed by our partner in the UK, Geomatrix Earth Science.

Hi All,   We are using the Teensy 4.1 as a logger (Adafruit GPS is linked with the Teensy) for the MFAM SX. Below is the code for the Arduino IDE (Teensy), for people who might find it useful, Roi   #include <NativeEthernet.h> #include <SD.h> // ---- NETWORK CONFIGURATION ---- byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; IPAddress ip(192, 168, 2, 10); IPAddress mfamIP(192, 168, 2, 2); uint16_t mfamPort = 1000; EthernetClient client; // ---- PACKET STRUCTURE ---- const int PACKET_SIZE = 1380; const int SAMPLE_SIZE = 32; const int HEADER_SIZE = 16; const int NUM_SAMPLES = 40; const int SD_CHIP_SELECT = BUILTIN_SDCARD; uint8_t buffer[PACKET_SIZE]; int bufferPos = 0; // ---- SD CARD ---- File logFile; bool sdReady = false; unsigned long sampleCount = 0; unsigned long fileStartTime = 0; char filename[32]; // ---- AUXILIARY CHANNEL STORAGE ---- double gyroX = 0, gyroY = 0, gyroZ = 0, gyroT = 0; double accelX = 0, accelY = 0, accelZ = 0, accelT = 0; double compassX = 0, compassY = 0, compassZ = 0, compassT = 0; // ---- GPS FROM ADAFRUIT MODULE ON SERIAL1 (Pin 0 = RX) ---- char gpsBuffer[256]; int gpsBufferPos = 0; char gpsString[128] = ""; char gpsDate[12] = "00/00/00"; char gpsTime[16] = "00:00:00.000"; bool gpsFix = false; uint8_t tsStatus = 0; // ---- OUTPUT CONTROL ---- // Set to 1 to log every sample, 10 for 100Hz, 20 for 50Hz, etc. const int DOWNSAMPLE_FACTOR = 1; // 50 Hz output int downsampleCounter = 0; // How many minutes per file. Set to 10, 20, 60, etc. const int FILE_MINUTES = 10; // ---- LED INDICATOR ---- // Off = starting up // Very slow blink (every 3 sec) = connected and logging // Fast blink (4/sec) = connected but no data arriving // Solid on = no SD card // 3 quick flashes then pause = cannot connect to MFAM const int LED_PIN = 13; unsigned long lastBlinkTime = 0; bool ledState = false; unsigned long lastDataTime = 0; // ---- FUNCTION PROTOTYPES ---- void createNewFile(); void parsePacket(uint8_t* pkt); void parseAuxChannels(uint8_t* sample, uint16_t frameID); void readGPS(); void parseGPRMC(char* sentence); void writeSample(unsigned long timestamp, uint16_t fiducial, double mag1, uint16_t mag1s, double mag2, uint16_t mag2s, uint16_t sysStatus); int16_t toSigned16(uint16_t val); void createNewFile() { static int fileNumber = 0; // On first call, find the next available file number if (fileNumber == 0) { char testName[32]; for (int i = 1; i <= 99999; i++) { snprintf(testName, sizeof(testName), "MFAM_%05d.txt", i); if (!SD.exists(testName)) { fileNumber = i - 1; // Will be incremented below break; } } } fileNumber++; snprintf(filename, sizeof(filename), "MFAM_%05d.txt", fileNumber); logFile = SD.open(filename, FILE_WRITE); if (logFile) { logFile.println("Mag 1,Mag 2,Fid,SysS,Mg1S,Mg2S,Gyro X,Gyro Y,Gyro Z,Gyro T,Accel X,Accel Y,Accel Z,Accel T,CompassX,CompassY,CompassZ,Comp T,Date,Time,TS Status,GPS"); logFile.flush(); fileStartTime = millis(); Serial.print("Logging to: "); Serial.println(filename); } else { Serial.print("ERROR: Could not create "); Serial.println(filename); } } void setup() { Serial.begin(115200); delay(2000); // Start GPS serial port (Adafruit Ultimate GPS defaults to 9600 baud) Serial1.begin(9600); pinMode(LED_PIN, OUTPUT); digitalWrite(LED_PIN, LOW); memset(gpsString, 0, sizeof(gpsString)); // Initialize SD card if (SD.begin(SD_CHIP_SELECT)) { sdReady = true; Serial.println("SD card ready."); } else { Serial.println("WARNING: No SD card found. Serial output only."); digitalWrite(LED_PIN, HIGH); } // Initialize Ethernet Ethernet.begin(mac, ip); if (Ethernet.hardwareStatus() == EthernetNoHardware) { Serial.println("ERROR: No Ethernet hardware found!"); while (true) {} } Serial.print("Teensy IP: "); Serial.println(Ethernet.localIP()); Serial.print("Connecting to MFAM at "); Serial.print(mfamIP); Serial.print(":"); Serial.println(mfamPort); if (client.connect(mfamIP, mfamPort)) { Serial.println("Connected to MFAM!"); } else { Serial.println("Connection failed!"); } Serial.println("Waiting for GPS fix..."); if (sdReady) { createNewFile(); } Serial.println("Mag 1,Mag 2,Fid,SysS,Mg1S,Mg2S,Gyro X,Gyro Y,Gyro Z,Gyro T,Accel X,Accel Y,Accel Z,Accel T,CompassX,CompassY,CompassZ,Comp T,Date,Time,TS Status,GPS"); } void loop() { // Always read GPS data from Serial1 readGPS(); if (!client.connected()) { Serial.println("Disconnected. Reconnecting..."); if (sdReady && logFile) { logFile.flush(); } for (int i = 0; i < 3; i++) { digitalWrite(LED_PIN, HIGH); delay(100); digitalWrite(LED_PIN, LOW); delay(100); } delay(1400); client.connect(mfamIP, mfamPort); if (client.connected()) { lastDataTime = millis(); } return; } while (client.available()) { buffer[bufferPos] = client.read(); bufferPos++; if (bufferPos >= PACKET_SIZE) { parsePacket(buffer); bufferPos = 0; lastDataTime = millis(); } } // LED patterns if (sdReady) { if (millis() - lastDataTime > 3000) { if (millis() - lastBlinkTime > 125) { ledState = !ledState; digitalWrite(LED_PIN, ledState ? HIGH : LOW); lastBlinkTime = millis(); } } else { if (millis() - lastBlinkTime > 1500) { ledState = !ledState; digitalWrite(LED_PIN, ledState ? HIGH : LOW); lastBlinkTime = millis(); } } } // New file every FILE_MINUTES minutes if (sdReady && logFile && (millis() - fileStartTime > (unsigned long)FILE_MINUTES * 60UL * 1000UL)) { logFile.close(); createNewFile(); } } // ---- GPS READING FROM ADAFRUIT MODULE ON SERIAL1 ---- void readGPS() { while (Serial1.available()) { char c = Serial1.read(); if (c == '$') { gpsBufferPos = 0; } if (gpsBufferPos < (int)sizeof(gpsBuffer) - 1) { gpsBuffer[gpsBufferPos] = c; gpsBufferPos++; } if (c == '\n' || c == '\r') { gpsBuffer[gpsBufferPos] = '\0'; if (strncmp(gpsBuffer, "$GPRMC", 6) == 0 || strncmp(gpsBuffer, "$GNRMC", 6) == 0) { // Save full sentence for logging strncpy(gpsString, gpsBuffer, sizeof(gpsString) - 1); gpsString[sizeof(gpsString) - 1] = '\0'; // Remove trailing newline/carriage return int slen = strlen(gpsString); while (slen > 0 && (gpsString[slen - 1] == '\n' || gpsString[slen - 1] == '\r')) { gpsString[slen - 1] = '\0'; slen--; } parseGPRMC(gpsBuffer); } gpsBufferPos = 0; } } } void parseGPRMC(char* sentence) { // $GPRMC,HHMMSS.sss,A,lat,N,lon,W,speed,course,DDMMYY,... char copy[256]; strncpy(copy, sentence, sizeof(copy) - 1); copy[sizeof(copy) - 1] = '\0'; char* token = strtok(copy, ","); int field = 0; while (token != NULL && field < 10) { switch (field) { case 1: // Time if (strlen(token) >= 6) { snprintf(gpsTime, sizeof(gpsTime), "%c%c:%c%c:%s", token[0], token[1], token[2], token[3], token + 4); } break; case 2: // Fix status gpsFix = (token[0] == 'A'); break; case 9: // Date if (strlen(token) >= 6) { snprintf(gpsDate, sizeof(gpsDate), "%c%c/%c%c/%c%c", token[0], token[1], token[2], token[3], token[4], token[5]); } break; } token = strtok(NULL, ","); field++; } // Update GPS bits of tsStatus tsStatus = (tsStatus & 0x0C); // Keep MFAM PPS bits (3,2) tsStatus |= 0x01; // Bit 0: RMC sentence received if (gpsFix) { tsStatus |= 0x02; // Bit 1: GPS fix valid } } // ---- MFAM DATA PARSING ---- int16_t toSigned16(uint16_t val) { if (val > 32767) return (int16_t)(val - 65536); return (int16_t)val; } void parseAuxChannels(uint8_t* sample, uint16_t frameID) { uint8_t auxID = (frameID >> 11) & 0x07; uint16_t aux0 = sample[16] | (sample[17] << 8); uint16_t aux1 = sample[18] | (sample[19] << 8); uint16_t aux2 = sample[20] | (sample[21] << 8); uint16_t aux3 = sample[22] | (sample[23] << 8); switch (auxID) { case 1: compassX = toSigned16(aux0) / 0.01333333; compassY = toSigned16(aux1) / 0.01333333; compassZ = toSigned16(aux2) / 0.01333333; compassT = toSigned16(aux3) / 128.0 + 25.0; break; case 2: gyroX = toSigned16(aux0) / 16.384; gyroY = toSigned16(aux1) / 16.384; gyroZ = toSigned16(aux2) / 16.384; gyroT = toSigned16(aux3) / 512.0 + 23.0; break; case 4: accelX = toSigned16(aux0) / 16384.0; accelY = toSigned16(aux1) / 16384.0; accelZ = toSigned16(aux2) / 16384.0; accelT = toSigned16(aux3) / 512.0 + 23.0; break; default: break; } } void writeSample(unsigned long timestamp, uint16_t fiducial, double mag1, uint16_t mag1s, double mag2, uint16_t mag2s, uint16_t sysStatus) { char tsStr[12]; snprintf(tsStr, sizeof(tsStr), "%d%d%d%d%d%d%d%d", (tsStatus >> 7) & 1, (tsStatus >> 6) & 1, (tsStatus >> 5) & 1, (tsStatus >> 4) & 1, (tsStatus >> 3) & 1, (tsStatus >> 2) & 1, (tsStatus >> 1) & 1, tsStatus & 1); char sysHex[8], m1sHex[8], m2sHex[8]; snprintf(sysHex, sizeof(sysHex), "%04X", sysStatus); snprintf(m1sHex, sizeof(m1sHex), "%04X", mag1s); snprintf(m2sHex, sizeof(m2sHex), "%04X", mag2s); char line[512]; snprintf(line, sizeof(line), "%10.4f,%10.4f,%4d,%s,%s,%s,%10.2f,%10.2f,%10.2f,%5.1f,%8.5f,%8.5f,%8.5f,%5.1f,%8.1f,%8.1f,%8.1f,%5.1f,%s,%s,%s,%s", mag1, mag2, fiducial, sysHex, m1sHex, m2sHex, gyroX, gyroY, gyroZ, gyroT, accelX, accelY, accelZ, accelT, compassX, compassY, compassZ, compassT, gpsDate, gpsTime, tsStr, gpsString); if (sdReady && logFile) { logFile.println(line); if (sampleCount % 1000 == 0) { logFile.flush(); } } if (sampleCount % 500 == 0) { Serial.println(line); } } void parsePacket(uint8_t* pkt) { // Get PPS bits from MFAM System status uint16_t firstSysStatus = pkt[HEADER_SIZE + 2] | (pkt[HEADER_SIZE + 3] << 8); uint8_t mfamPPSbits = (firstSysStatus >> 12) & 0x0C; tsStatus = (tsStatus & 0x03) | mfamPPSbits; for (int i = 0; i < NUM_SAMPLES; i++) { int offset = HEADER_SIZE + (i * SAMPLE_SIZE); uint16_t frameID = pkt[offset] | (pkt[offset + 1] << 8); uint16_t fiducial = frameID & 0x07FF; uint16_t sysStatus = pkt[offset + 2] | (pkt[offset + 3] << 8); uint32_t mag1raw = pkt[offset + 4] | (pkt[offset + 5] << 8) | ((uint32_t)pkt[offset + 6] << 16) | ((uint32_t)pkt[offset + 7] << 24); double mag1 = mag1raw * 0.05 / 1000.0; uint16_t mag1status = pkt[offset + 8] | (pkt[offset + 9] << 8); uint32_t mag2raw = pkt[offset + 10] | (pkt[offset + 11] << 8) | ((uint32_t)pkt[offset + 12] << 16) | ((uint32_t)pkt[offset + 13] << 24); double mag2 = mag2raw * 0.05 / 1000.0; uint16_t mag2status = pkt[offset + 14] | (pkt[offset + 15] << 8); parseAuxChannels(pkt + offset, frameID); sampleCount++; downsampleCounter++; if (downsampleCounter >= DOWNSAMPLE_FACTOR) { downsampleCounter = 0; writeSample(millis(), fiducial, mag1, mag1status, mag2, mag2status, sysStatus); } } }

hello Im having problems with MagArrow II data recording, and i'd love some help or advice.The issue definatly is a problem with the SD connection. Im having no troble connecting to the sensor's WIFI, but when heading to the "Data" page I get the massage "Unable to load servays. Verify that the SD card is insrted correctly. [...]" Indeed in Systemtest page i get a "SD card: Failed" test. Im aware of the SD's spring load mechanism, and tried many times in different configurations, including trying with different SD cards, updating the MagArrow software, but to no avail. The System just wont recognise any SD 🙁 Anyone had a similare problem? Any tips or suggestions?I'd love to get the sensor working again

Some of the Geometrics magnetometers include a feature, called the "File Cleanup Utility", that removes files that are no longer useful from storage on the instrument. The feature's accessible from the "Support" link in the Settings page in MagNav. You might be reading this post because that page directed you to read this post before using the utility. [This feature is not the same as the feature in MagNav to delete all of a survey's data. That feature removes information only from the database on the Android tablet, and doesn't remove any data in the instrument]. How do I use this feature? If this is the first time you've used this feature, please read the rest of this post before proceeding. Make sure that you're connected via WiFi to the instrument Go to the Settings page in MagNav Select the "Support" link. If your instrument supports this feature, the support page will include a link to "Delete project storage". Tap it. You should see a list of projects, with a name and a "Delete project" button for each project. This feature cleans up the data for all of the surveys in a project. Delete any projects for which you don't want to keep the in-instrument data. You can delete the data for all of the projects that you see, but there's no harm in leaving the files for projects that you're still using. Some projects will show a name similar to this: [c3bd]. These are early projects, in which the user-assigned name was not used in the instrument storage. It's OK to remove the data for these projects. Why do I need to do this? The magnetometers that use MagNav first store data on the instrument, and then sync (or download) the data to MagNav. Some instruments, for which this technical approach makes the instrument more reliable - MagEx, e.g. - do this automatically. Other instruments, such as those that allow disconnected acquisition (e.g. MagStation), store the data until the user re-connects to the instrument and manually starts the sync process. The data stored in the instrument is not of any use once it's been downloaded, but because deletion is slow and for other technical reasons, it's left on the file System in the instrument. As it accumulates, it could eventually interfere with the performance of the instrument and should therefore be deleted. Will this delete any data in the database in MagNav? No, this feature doesn't remove or change any data in the database in MagNav. When should I use this feature? Here are a few guidelines: Run this utility after deleting an entire project. Run this utility after completing a long field survey. Run this utility while doing other instrument maintenance. Run this utility after you've collected "a lot" of data. Run this utility when you have the impression that the instrument is unresponsive or is behaving sluggishly. Will anything bad happen if I forget to do this? Probably not any time soon; the storage Systems on the instrument are large and quite efficient. Geometrics tests instruments with amounts of data consistent with several years of regular use, and which show no performance issues relating to file storage performance. But don't let it go forever; follow the guidelines above. Can I delete data for projects that I'm still using? Yes, you can, as long as the data has already been synced to the instrument (that happens manually with MagStation and automatically with the other instruments). Once the data has been synced and is visible in MagNav, its presence in the instrument storage is no longer needed.

I have set up a G-882 System here at Geometrics and am receiving data and sending commands using TeraTerm (any terminal emulation program should work). When in normal use mode the Digital add on board sits in front of the G-882 and parses and acts on all commands coming in. There are two versions of the Digital Add On board, which are the GP120 and the GP140. The GP140 is a newer version of the Digital Add ON board. It is the GP140 Digital board that outputs all S/N (and other) information. I first set up with the GP140 board (the newer version). I find that the ""RESET" command does work - i.e. it goes into BYPASS mode for a couple seconds, then output the S/N and configuration information, and reverts to normal operation with the digital depth and altimeter information. But it only works every other time I send it. The first time nothing happens. Then I send it again and it works. This appears to be a bug in the GP140. For some commands the first command after power up or reset are ignored. The second time (and subsequent commands) are executed. The work around seems to be sending the RESET command twice. I also tried an older G-882 with the GP120 Digital board. The Reset (and other commands worked first time and every time. BTW, the Digital Board version is in the second line with the S/N information that is sent on power up or Reset. Some questions: 1) My configuration is one G-882 connected to a PC through the white junction box. Is this your configuration, or do you have concatenated G-882's? 2) Can you get the G-882 to accept any commands (like going into Bypass Mode)? I'm wondering if there is a open link in the command line from the PC to the Digital board.

Hello all, I'm currently working on a software project to integrate some Maggy's more effectively into our System. I see that when the magnetometer starts up it outputs it's serial number as well as some other useful information. I'd like to know if there is a serial command I can send that will initiate that information? A reset command for instance. I've read the manual and it suggests that I can simply send 'Reset' via a serial console but have tried it multiple times and have not been able to receive that initial startup string when I try it. Am I missing something? Or is there a terminator that I'm missing? I know it's possible as the digital console software can live reset the Maggy while it's sending data (same as what I want to achieve) so any help you could offer would be very gratefully accepted. For your information I've used multiple serial console softwares none of which have worked

Hi Anton, We are not aware of any special grounding schemes for a large number of modules. In dealing with EMI interference, our experience is that you need to individually ground each Geode - how you do it depends on the conditions you are in, but generally a Metal stake with a wire to the grounding post is the best you can do. Sometimes adding a little water to the soil around the stake can help. We have seen a majority of this type of noise occur in highly resistive environments (dry sands or hard rock), and grounding can help. If you are able to orient the lines perpendicular to the transmission lines that can also help. In general, with high voltage lines, the emanating field (50 or 60Hz) is likely coupling into the spread cable. Each geophone pair in the spread cable is a big antenna, but the pairs are twisted so any signal induce in one will also be induced (in varying degrees) into its neighboring wire. This will lead to a common mode voltage at the input to each Geode channel. So it would depend upon the common mode rejection (CMR) of the Geode’s input amplifier to reject this common mode signal. But the CMR of an amplifier is finite, and if the common mode signal is large, the common mode range of a given channel can be exceeded leading to the 50 or 60 signal being amplified by the front end differentially resulting in a lot of noise. This can happen even with very good CMR. Also any unevenness in the spread cable pair twists will result in a differential signal which will be amplified by the System. We would also suggest trying the lower gain setting, in case the front end is being over driven. You may need a bigger source to overcome the loss of amplification, but if you can get data, even with substantial 50 60z noise, a post processing 50 or 60Hz filter may be able to clean up the record enough to be useable. We haven’t tried this, but if everything else failed then this might be worth trying: It is possible that the noise is being induced in to the coils of the geophones. If that’s the case, then putting a metal can over the affected geophones might help. Note that the cans might have to be grounded with a metal stake driven into the earth.

Hello, guys.I need to ask some questions about grounding technique for Geode seismographs. Current territory that we need to investigate has strong electromagnetic pollution from nearbuy high voltage power line. When using 48 to 96 geophones many channels experiencing strong EMI interference in wide spectrum. So I want to ask the forum society for some advices on the grounding technique of Geode modules. Because in documentation there is only a mention of "grounding plug" on the side of boxes. But there is no advices on how to properly ground 4 or more modules, distanced 240 meters from one another. Even more when soil has different properties along streamer line (moisture etc). On geometrics.com could not find any instructions on rightful grounding technique. Maybe there is exist some sort of special grounding schemes for large number of modules in use. As I understand the better way is to have star topology for grounding (with one common rode point for several devices) when using spreaded device System. Because in other cases ground potential for different modules will vary. Maybe I asking a silly quastion but EMI problem anyway exist on long receivers arrays. That ruins noise/signal ratio and etc. Thanks.

Here are a few additional details relating to the measurement of elevation: GNSS AccuracyAccuracy depends on multiple aspects of the GNSS System: among them are clock accuracy, atmospheric effects, and satellite geometry. Satellite geometry"Satellite geometry" refers to how the currently visible satellites are distributed in the sky - close to each other or scattered around. The best satellite geometry includes satellites that are near the axes on which you hope to locate your receiver; for example, to locate your receiver on the East/West axis, it's helpful to have good reception from satellites low in the sky in the East and in the West. If you also have satellites that are low in the sky near the South and North horizons, you will have good accuracy on the horizontal (latitude/longitude) plane. It's best to have satellites scattered around the sky, overhead as well as near the horizon all around. HDOPMagArrow records HDOP, a standard measure of satellite geometry's effect on horizontal (or latitude/longitude) accuracy. A smaller number (less than 1.0 is very good) indicates that the visible satellites are in good positions to contribute to accuracy. Vertical AccuracyThe reason that GNSS Systems aren't as accurate on the vertical axis as on the horizontal axes is that no satellites are visible in a full half of that axis: the half that is below the horizon. Consequently, vertical accuracy is on average about half that of horizontal accuracy; calculated offset from true elevation is on average about twice that as on the horizontal axes. While on average HDOP can therefore be used to estimate VDOP (the similar measurement of the effect of satellite geometry on the vertical axis), that estimate is only a rule of thumb; it is possible to have an excellent HDOP, reflecting very good horizontal satellite geometry, while having poor vertical satellite geometry. In those cases, good HDOP does not indicate good VDOP. Keeping in mind that possibility, a combination of good HDOP and many satellites in view usually indicates good VDOP. Practical effects Some data processing techniques (upward continuation, for example) can include elevation as an input. Customers who are considering using GNSS elevation in those techniques should conduct a careful analysis of their data and develop test routines to verify that all their data meet the requirements of the technique and its application to a particular survey. Some customers who require very accurate elevation data incorporate LIDAR data and drone elevation data into their analyses.

Attachment : MagMap_W11.pdf It has been reported that the MagMap software does not work with some versions of Windows 11. The following error is shown: C:\Program Files (x86)\MagMap\olch3d32.dll is not intended for use with Windows or contains an error. Try reinstalling the program from the original installation media or contact your System administrator or software vendor. Error Status: 0xc000000d Solution: There's a setting in the Windows Security that needs to be changed. See attached.

Hello, we have 2 MFAM Systems with 2 OPMs each, and would like to measure in sync. We saw that we can add a 1 PPS pulse as sync trigger when GPS is not available. But on Software side, MagView can only read from one System, and we could not figure out how to open 2 MagView instances on the same computer. (We would not like to use 2 computers...). Is there an easy way how we can achieve this? Thanks in advance.

1. Make sure the MagArrow top cover (the curved side) is facing up and under a clear sky. 2. It may take up to 20 minutes for the GPS to lock during the initial power up. Afterwards, the GPS stores the location information for a while (~40 minutes for MagArrow I and ~ 2 hours for MagArrow II) without the power so that it can lock much faster than 20 minutes (~2-3minutes) during subsequent powerups. 3. If the powerup locking time is significantly longer or intermittent GPS dropouts are observed during flight: MagArrow I will need to be sent back to Geometrics for repair. MagArrow II customers may choose to unscrew the external helical antenna (or attach the external helical antenna) and check whether the longer-than-normal locking time or the intermittent issue goes away. MagArrow II has an independent internal and external antenna design. When the external helical antenna is attached (unattached), the System switches to the external (internal) antenna automatically.

Can I do refraction on pavement? It is exceedingly difficult to do this, because the pavement is generally has a much higher velocity that the materials below it. It is generally not recommended. Can I do refraction on a hillside? Yes. The slope of the surface is not relevant (at least in theory, although there may be obviously practical limits). Can I survey in the rain? Rain won’t hurt the seismographs. If you are using a StrataVisor or SmartSeis and it starts raining, they should be fine as long as they are kept vertical, with the screen pointing up. But acquiring data in the rain should be avoided, especially if there is lightning. Even in the absence of lightening, rain can be a significant source of noise, especially those raindrops striking the geophones directly. Obviously, the harder the rain, the more noise. If waiting the rain out is impractical, shielding the geophones themselves can reduce the noise significantly. If for some reason the seismic System must be left on the ground during an electrical storm, it is advisable to disconnect the trigger and geophone cables from the seismograph.

The de facto "standard" for high-resolution reflection is 40-Hz geophones. The 40-Hz cutoff will filter out much of the ground roll, allowing you to use the maximum gain even at near offsets, and taking advantage of the full dynamic range of the recording System.