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MagStation, the new MFAM magnetometer base station is available. It's Geometrics’ latest and most advanced magnetometer base station, designed for high-sensitivity, stationary monitoring of the Earth’s Total magnetic field. Please see the product page for details.
MagStation Magnetometer Base Station
Thank you for detailed answer.
I understood that common practice is separate grounding of each module. Also we will definitely try to shield each geophone with a separate ground, but this will require a large amount of preliminary work.
Regarding 50 Hz filtering.
We conducted a small experiment in the field to determine the frequencies of background electrical noise captured by geophones. Having set the minimum possible sampling period for Geod, I recorded 9 consecutive intervals (128 seconds each) of passive observations. This resulted in a Total of 19.2 minutes of continuous background noise recording at 125 Hz sampling rate.
Then I calculated the signal spectrum from each geophone separately (19.2 minutes of recording), and then obtained the average spectrum for all sensors. For example, the figure in the appendix shows the average spectrum from 24 sensors (red curve) versus the spectrum of an individual geophone (blue curve).
In general, I am interested in noise in the 30-50 Hz range. There are no clear peaks at 50 Hz on the frequency response graph. Peaks at 20, 25, 30 Hz are present constantly at any time of the day. In general, the frequency response of passive observation signals increases smoothly with a maximum around 48 Hz.
I mean that filtering in some narrow frequency range in this case will not help much in my understanding.
Thanks again for the advice. We’ll experiment.
Attachment : 24 geophones 19.2 minutes 125 Hz sample rate.jpg
Hello Dears,
I'm new to Geometrics products and interested in MagArrow. I have some questions please. As a geophysicist, I examined the attached data and applied heading compensation to the measured data. My questions are after applying the 4th difference filter (the last panel in the attached figure) which is very important for measuring data noise especially comTing from the drone. I found the range to be very high and exceeding +/- 0.1, even after applying low pass filter to reduces the sampling rate of data from 20 Hz to 10 Hz. I think one of the biggest advantages of the MagArrow is that the sensor is suspended 3 meters below the drone to cancel out the effect of the noise coming from the drone, so I need to explain that.
Attachment : 4th difference.jpg
Secondly, in the attached file of the survey, the range of the Total magnetic field data is about 43,000 nanoTesla, while when calculating the IGRF for that region based on longitude and latitude, I found that the range is about 49,000 nT, which is very far from the measured data? Could you please explain to me the answers to these questions because our goal is to explore minerals and not UXO.
Kind Regards,
Ahmed
The cables between the sensors and the MFAM module are flexible circuit boards, and the length is limited to 20 inches.
It is possible to remove the MFAM module from the Development kit box and then reconnect it using a ribbon cable. That would allow you to extend the MFAM module and sensors away from the Dev Kit box. Our engineers have tested it to 4 meters.
Below are some details about the ribbon cable.
The connector on the MFAM unit is Samtec FSH-110-04-F-DH. Its mating connector is Samtec SFMH-110-02-L-D-WT.
The easiest option for an extender cable between the MFAM and the Dev Kit is a pair of cable assemblies from Samtec www.samtec.com which has male/female mass terminate connectors put onto a ribbon cable. These connectors plug directly into the MFAM I/O connector and also into the Development Kit. We are comfortable with lengths to 10 feet Total. The samtec P/N for this cable is: FFMD-10-T-60.00-01-F-N
The ‘60.00’ number specifies the cable length in inches (which equals 5 feet). We have found that there is generally a 2-4 week lead, time since they are made to order and not an off-the-shelf part.
(There is another solution as well if you want to make adapter boards at each end (Dev Kit and MFAM). The exact Samtec mates for the MFAM / Dev Kit connectors are made in PCB mount connectors only, so if you make simple small adapter board to adapt the samtec connector to another connector of your choice. We've done this with ExpressPCB which is fast and inexpensive. A board set from ExpressPCB is about $70 including shipping. Our Engineering Team has a design and parts list they can send you if you're interested in going this route.)
There is no one right answer to this question. The higher the channel count, the higher the fold (for any given shot interval), and the higher the signal/noise ratio. For land seismic, we generally recommend 24 or higher-fold data. If the shot spacing is equal to the geophone spacing (typical), this means that you must record on at least 48 channels with each shot. In addition, you must have extra channels for electronic rolling. Taken together, this means that for land CDP reflection, you should have a minimum of 72 channels, which will allow you to roll 48 live channels through a Total of 72.
Our cesium-vapor magnetometers do not require periodic calibration in order to maintain the accuracy as described in our published specification when the instrument is operated within specified environmental ranges. Geometrics cesium-vapor magnetometers are manufactured and tested based on the discoveries and the basic designs of Carian Associates (U.S. Patent 3,071,721). This method of Total magnetic field measurement relies upon the measurement of the optical absorption of a particular cesium spectral frequency by the cesium vapor enclosed in a small glass cell. This method is similar to those used in the measurement of atomic emission and absorption frequencies using spectroscopic reference cells. The technique thus relies on well-known fundamental quantum mechanical constants for accurate and precise measurement of the magnetic field. As a result, no adjustments to the sensor are needed in order to correct or maintain its accuracy and Geometrics sensor and sensor driver electronics are designed to either work correctly or to not work at all and to report both the strength of the magnetic field as well as the strength of the electrical signal produced by the working sensor. In this way, the signal strength measurement provides a direct indication of the operational state of the magnetometer while it is running and serves to alert the operator if the magnetometer encounters environmental conditions that are outside of its operating range.
Occasional maintenance of the instrument at Geometrics facility should be performed when the instrument's internal diagnostics indicate substandard performance as described in the operator's manual.
Please contact Geometrics Support for technical advice and additional information pertaining to your specific model.
Overview
The MagEx instrument and the MagNav app both display information about the state of the instrument's battery. Battery state and reporting exist in bands according to percentage of remaining battery capacity:
30% or higher:The instrument has good remaining capacity.The LED on the instrument's power switch glows a solid green.MagNav displays the battery percentage or voltage in black text on a white background.
Between 20% and 30%:The instrument has capacity to survey for additional time, but if you will be surveying a significant amount more, start thinking about changing the battery.The LED on the power switch is blue.MagNav displays the battery percentage with a blue background.
Between 5% and 20%:You can continue to survey, but the battery is running low and you should consider changing the battery soon.The LED on the power switch is red.MagNav displays the battery percentage with a red background, and periodically notifies you that the battery is running low.
Below 5%:The battery is running low, and the instrument may turn off at any time in order to preserve battery health. You should change the battery as soon as possible.
Temperature-related effects:Battery performance also changes as the temperature of the battery changes; as the temperature of a battery falls, the voltage it supplies also decreases, and the Total energysupplied by the battery decreases. This means that in cold weather a battery will not last as long as in hot weather.
The battery percentages reported in the instrument are adjusted for the effect of temperature; at a given battery voltage a cold battery will display a higher percentage than a warm battery will report.
The effects of colder temperatures are not normally permanent; as a battery warms up, its output voltage and energy return to higher levels.
Notes about the calculation:The MagEx instrument includes 2 batteries, and each battery includes 3 separate cells. Battery percentages are calculated from only one battery in the instrument - either the single battery if only one is connected, or from the better battery if two batteries are connected.
Reported battery percentage is an estimate, based on measurements of the behavior of healthy batteries in instruments in the field and in the lab. Battery performance may change as a battery ages and as the temperature changes.
The best practice for batteries is to use 2 healthy, fully charged batteries, and replace them both when the percentage falls below 20%.
Clarification regarding Geometrics standard magnetometers
SX versions and the US Govt. export regulations
In this brief review magnetometer specifications are given in terms of both nT/sq-rt-Hz RMS and in Peak-to-Peak (P-P) noise values as both forms are often used to describe instrument performance.
The US Government specifies that an export license is required for magnetometers that have a sensitivity of better than (noise level less than) 0.02nT/sq-rt-Hz RMS. Obtaining an export license is not difficult but it does require approximately 6-8 weeks. Not all geophysical applications require export license sensitivity and so we offer SX models that have a noise floor of 0.02nT/sq-rt-Hz RMS. Compare this with our G-858 Magnetometer at 0.008nT/sq-rt-Hz RMS and our G-882 Marine Magnetometer at 0.004nT/sq-rt-Hz RMS.
What does SX performance mean in the survey results? When the sensor is deployed at some distance from the “source” such as in above the shoulder mounting for geological surveys (G-859SX) or at some distance (several meters) from the seafloor for G-882SX surveys, the distance from the source provides some natural filtering of the near surface response. This means that surveys not focused on small target detection (20mm ordnance rounds) where the sensor is deployed very close to the ground (<1m), SX performance is more than adequate.
Let us consider the G-858 man-portable model. Under low noise laboratory conditions at a sample rate of 10 samples per second, the G-858SX will show approximately 0.125 nT of noise (peak-to-peak) compared to a standard G-858 of about 0.05nT P-P. To understand the significance of this, the natural earth background noise due to geomagnetic micro-pulsations is about 0.02nT/sq-rt-Hz (about 0.125 nT peak-to-peak) at the quietest of times. Micro-pulsation amplitudes of 1 or 2 nT are common and, during active periods, they may be larger than 10 nT.
Any magnetometer will produce a record of the combination of the background noise (micro-pulsations, diurnal drifts, etc) and its own internal noise. If the various noise components are not correlated with each other they will add as the square root of the sum of their squared amplitudes. In the case of the G-858SX, the combination of instrument noise and background micro-pulsations will be:
√(0.125nT^2 + 0.125^2) = 0.18nT.
For the standard G-858, this combination will be:
√(0.05nT^2 + 0.125^2) = 0.13nT.
That is, the SX model will exhibit about 30% more noise amplitude compared to the standard model if the atmospheric noise is typical. Unless the survey measurements are referenced to a high performance base station magnetometer equipped with a very accurate clock, the user will not be able to detect any difference between SX and standard performance. If such base station data were available, the greatest difference that would be seen should be no greater than about 0.05nT P-P in the average peak-to-peak amplitude. Such small differences cannot be seen or even detected in the Total field contour maps made for exploration surveys which are typically contoured at 1nT or more.
It should be remembered that the amplitude of the geomagnetic micro-pulsations in the frequency range from 5hz to 10hz is not constant; i.e., at most times they will be greater than 0.125nT and occasionally less than this value. Their intensity is governed by the average intensity of the instantaneous global thunderstorm activity and sunspot activity.
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.
This is most likely due to the fact that land surveys are typically much closer to the ground (therefore closer to targets). Two spatially separated magnetic anomalies can be resolved on the ground but not several meters above the ground, as shown in the simulation plot below. The simulation is for two targets, separated by 4m, located at z= -2m, y=3m, x= 0m and z=-2m, y=7m, x=0m. The Total magnetic signal on the x=0 plane from the two targets are plotted in 2D as a function of y and z (with z=0 being on the ground).
For land magnetometer surveys, z = 0.5m or less. If we draw a line at z = 0.5m (survey line), it is clear that there will be 2 peaks in the sensor reading along y direction as long as the magnetometer has a high enough sample rate. Therefore, the two targets can be resolved.
For MagArrow surveys, if the above ground level (AGL) is >3m, the two targets cannot be resolved no matter how high the sample rate is.
This simulation also indicates a rule of thumb about the linespacing in MagArrow surveys. The linespacing should be about 1-2 times the AGL. Less than the AGL will not produce any higher resolution map.
The simulation plot provides customers with a general idea of how fast the magnetic signal decays as a function of distance from the target. The signal falls as 1/R^3.
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.
Total field magnetometers like the optically pumped cesium magnetometer are passive devices, they do not send out waves or pulses. They measure distortions in the earth’s normally homogenous magnetic field and can sense distortions due to ferrous objects at great distances.
The basic rule of thumb is that one ton (1000 Kg) of steel or iron will give us a 1nT anomaly at 100 ft. or 30m. Since the amount of distortion falls off as the cube with distance (compare a metal detector which falls off as the inverse 6th power!) and is linear with mass, every time we cut the distance in half, we can see 1/8th the mass. Therefore, we can sense 250 lbs. (100kg) at 50 feet (15m), or 30lbs (15kg) at 25 feet (8m), or 4lbs (2kg) at 12 feet (4m).
However this is not the whole story. The factors given above are for induced magnetic fields only. Many targets also have remnant or permanent magnetic effects (meaning they have become magnetized either in production or by the earth’s field) and can therefore have larger anomalies by a factor of 3 or 5 or more. Also many hollow objects like barrels or other tubular structures appear as though they are solid due to self-shielding from the earth’s field, and thus have much larger anomalies than their mass would predict alone. Pipes fall off as the inverse square and are thus detectable at even greater distances. Please see our Applications Manual for Portable Magnetometers for more information.
1. Establish WIFI connection between your PC and the MagStation.
2. Open a web browser and Type in .
Attachment : image.png
3. Click "Delete project storage" or "Download survey data" to delete or down raw data from micro-SD card. We recommend deleting raw data files after 700 hours data collection.
4. The downloaded survey data is in .magdata format. To convert it to CSV, open Survey Manager and create a new MagStation project. Inside the project, create a new survey. Select the survey name, click "Import Data" and then choose the .magdata file. After successful import, click "Export CSV".
Hello, I wanted to try our MagEditor software, but it didn't accept any of the files I converted to 10 Hz, 20 Hz, 50 Hz, 100 Hz, and 1000 Hz CSV formats from Survey Manager. What's the reason and how can I fix it? My operating system is Windows 11 Home Single, and my computer specifications are:Processor: Intel(R) Core(TM) i9-14900HX (2.20 GHz)Installed RAM: 32.0 GB (usable: 31.6 GB)System Type: 64-bit operating system, x64-based processor.
________Install 4ea new AA battery.
________Install dummy blasting cap to “CAP” of HVB. Make sure a wire touch the pencil lead. See attached picture.
Connect the Bendix trigger connector to the Seismograph.
Press “ARM” button (and keep pressing “ARM” button thru all test finished) and observe LED on the “READY”. It takes around 1-2 second after pressing “ARM”.
_____________”READY” LED on around 1-2 second after pressing “ARM” switch.
Make sure wearing safety glasses to protect your eyes for next test.
_____________Wear safety glasses.
Press “FIRE” button while pressing “ARM” switch. Observe dummy led cap sparks and “READY” LED off, and trigger the Seismic unit.
_____________Dummy led blasting cap sparks
______________”READY” LED off.
______________Trigger the Seismic unit
After firing the cap, “READY” LED lit on again within 5 seconds later
______________Within 5 seconds after firing, the “READY” LED on again.
Pressing “FIRE” again. You may adjust dummy led blasting cap to see sparks.
______________Fire works again.
______________Trigger works again
Continue firing HVB 5 times.
______________It works 5 times.