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| # | Post Title | Result Info | Date | User | Forum |
| Why does data transfer through WiFi become slow? | 11 Relevance | 1 year ago | Rui Zhang | Hardware | |
| If the system has a large amount of survey data, it may affect the data transfer rate. Sometimes a very slow SD card makes the system unresponsive; to the user this can look like a slow/bad network connection. Therefore, it might be useful to clean up the SD card and USB drive. Delete the Geometrics.log file on the USB drive. Clean up the survey data on the SD card: First, make sure that you have all the data that you need off of the SD card. Either download all survey data that you want to keep, or copy all of the contents of the SD card to another drive (perhaps to a PC). Delete all of the data on the SD card, doing one of the following: Use the UI to delete all of the surveys, then use the "Clean old files" button on the Admin page to empty the recycle bin on the SD card. This can be VERY slow, and because the MagArrow has a very simple web interface, the user will get no useful feedback. On a very full SD card, this process might take 30 minutes or so. Or.... Remove the SD card from the MagArrow and after copying any data that the user still hasn't saved to a PC, format it or delete everything on it, then re-insert it. Be careful not to lose the SD card or to let it drop into the inaccessible spaces in the instrument. If you format the SD card, the ExFAT format is preferable. If the customer can't get the data downloaded from the instrument (takes too long or stops), the data can be imported into a survey in Survey Manager, directly from the SD card (or from the PC hard drive to which the SD card data has been copied). Then the SD card can be cleaned up or formatted. With the new version of Survey Manager (you need to update that also, not just the instrument software), the user can import a large survey, including all of the files in subdirectories, by selecting the "acquinfo.txt" file in the root directory of the survey, from the SD card. More details about how to import/export SD card files using Survey Manager can be found in the post below: SD card files conversion | |||||
| Understanding Acquisition Filters in Seismographs - Their Use and how to Filter | 4 Relevance | 2 years ago | Gretchen Schmauder | Software | |
| Low Cut: , 10, 15, 25, 35, 50, 70, 100, 140, 200, 250, 280, 400 Notch: 50, 60, 150, 180 High Cut: 32, 64,125, 250, 500 or 1000 Hz The first recommendation for cases when you are having trouble getting sufficient signal to noise would be to increase your signal via stacking the data with multiple source events or get a more powerful seismic source. This will usually produce better results than the application of filters. Another approach would be acquire data when the noise sources are less present. That may mean collecting data at night when the area is closed or the traffic is less. Early morning can be better for areas where the wind tends to increase during the day. The selection of filters is very site dependent and can depend on a variety of factors as well as the Type of survey being performed. 1) Typically the Notch filters are to remove noise due to electrical power lines (50 or 60 Hz and their harmonic frequencies depending on the country you are in). 2) Low cut filters are generally used for noise due to wind and moving vehicles, but care must be taken not to remove too much bandwidth from generated seismic signal. Often the noise sources have the same frequencies as the seismic data you are interested in and can’t be effectively removed using frequency filtering. 3) High cut filters can be used to remove noise from high frequency vibratory signals such as compressors or airplanes. In general it is best to record the data without any frequency filters and filter in post processing or only on the displayed data in our software. It will be a matter of experimentation to determine the best filters at your site. Modern 24-bit seismographs (Geode, Stratavisor, ES-3000, etc) have a much wider range of signal amplitudes that they can record accurately. This means that they can still accurately record smaller seismic signals even in the presence of larger noise signals. Therefore there is a reduced need for analog filters that are applied prior to digitization of the signals. Digital filters are more flexible and can be more specifically applied to the noise that is recorded rather than the “Broader Brush” of analog filters. Digital filters also have the benefit of being able to go back to the original data if the wrong filter is applied, which is not the case with Analog filters. The general approach in the seismic industry is now to record everything – including the noise – and the filter out what you don’t want later. | |||||
| RE: microSD card type and format | 4 Relevance | 11 months ago | Rui Zhang | Hardware | |
| @georesults The microSD card is used in MagArrow, G-864, MagEx and other soon-to-be-released products. | |||||
| RE: microSD card type and format | 4 Relevance | 11 months ago | Peter McMullen | Hardware | |
| Thanks Rui. But for which Geometrics hardware products? | |||||
| microSD card type and format | 4 Relevance | 11 months ago | Rui Zhang | Hardware | |
| We suggest using microSD cards with specs equivalent to or better than SanDisk Extreme and format it to exFAT. | |||||
| How do you decide what type of strike plate to use for a seismic survey? | 4 Relevance | 2 years ago | Gretchen Schmauder | Application | |
| Below is a series of diagrams that can act as analogies for impacts. If the impulse is enacted rigidly (hard tip hammer, steel plate, etc.), the impulse will look something like the far-left figure. High-amplitude (height of the curve), narrow wavelength (width of the curve). This is because the impacted materials respond rigidly to the impulse, i.e. the hammer rebounds from the plate almost instantaneously. Therefore, as a result of the narrow-wavelength impulse, the transmitted waves will have relatively high-frequency (short wavelength) content. As you use softer and softer impact materials, applying impulses of equal force will appear like the diagrams to the right (smaller amplitude, longer wavelength). The impacted materials are responding less-rigidly to the impulse, so the hammer spends more time on the plate due to the more absorptive nature of the impact. The same amount of energy has been put in (area under the curve), but the amplitude of the input (height of the curve) decreases to compensate for the input duration (width of the curve) caused by the impact absorption of the softer materials. Therefore, as a result of the wide-wavelength impulse, the transmitted waves will have relatively low-frequency (long wavelength) content. Using a more rigid striker plate (like one made of aluminum) on a hard surface can cause the generated wave frequency to be too high at times given the survey goals, so we suggest using a polyethylene plate on a relatively solid material like asphalt. Remember: lower frequency -> deeper signal penetration -> decreased signal resolution. | |||||
| MagArrow Heading Error Compensation Flight FAQ | 3 Relevance | 2 years ago | Gretchen Schmauder | Application | |
| To perform a heading error compensation flight, fly the UAV with MagArrow attached up to 100-150 meters in a low gradient area. Hover the drone in a single spot and rotate it slowly through 360 degrees while logging magnetic data the with MagArrow. By keeping the drone location stationary the mag field will be also be constant. Thus we are only left with the sensor reading as a function of orientation. The MagArrow has two MFAM sensors, and the way they are arranged ensures that when one sensor is in its dead zone the other is at its optimum orientation, and vice versa. The readings from the two sensors are combined to produce one magnetometer reading only. The two sensor readings are weighted such that as one sensor approaches its dead zone it is weighted much less (down to zero in the dead zone) while the optimum oriented sensor is weighted more fully. Thus you get only one magnetometer reading with no dead zones whatsoever. In addition, the weighted averaging of the sensors still does partial heading error cancelling. | |||||
| 1000 Hz Sample rate and Powerline Variations | 3 Relevance | 2 years ago | Gretchen Schmauder | Application | |
| The MFAM Magnetometer samples at 1000 Hz, which in turns captures a lot of unique waveforms. When viewing the data raw, it can therefore appear to be a bit noisy. But a closer examination of the data will reveal a real variation of the magnetic field which is caused caused by the power distribution network. Proper filtering is required to reduce the power line caused variations and reveal the strong signal of interest. It is not obvious that 60 or 50 hertz electromagnetic radiation is real, since in ordinary experience any power line “noise” is electrostatically coupled into a system (think 60 hertz hum on a stereo system) and is a fault that needs to be fixed. In this case however the variation in the magnetic field is induced by the power grid and is real. The magnetometer is simply and dutifully reporting the variation. These power line variations are to some extent present everywhere – even miles from the nearest power line. But obviously being close to power lines will increase the amplitude of the variations a lot. Often on a MagArrow survey the power line variations will be larger at one end of the survey area than the other. Poking in the GPS coordinates at the survey area nearest the larger variations into Google Earth will usually reveal the power lines from an aerial view – even if they are not visible on the ground. After applying a Fourier Frequency Transform on the MFAM data to identify the noise sources, 50 and 60 Hz noise amplitudes are easily observed. Also observable is the likely to be 20.8 Hz Schumann resonance of the third node and some other ultra-low frequency electro magnetic radiation produced naturally by the Earth. Harmonics of 60 Hz are also present. Another common question is “Why is the power line variations not a sine wave like the power line voltage?” Remember that voltages do not make magnetic fields. Only current generates magnetic fields, and the current being drawn is not a sine wave at all. Many loads, for example, only draw current at the voltage peaks. This makes for a non-sinusoidal magnetic field that is rich in harmonics. Also note that most power distribution system use a 3 phase topology. The ripple current in such a system will be 150 or 180 Hz. Thus you will often see large peaks in the power spectrum at these frequencies and their harmonics. | |||||
| 1000 Hz Sample Rate and Powerline Variations | 3 Relevance | 2 years ago | Gretchen Schmauder | MFAM | |
| The MFAM Magnetometer samples at 1000 Hz, which in turns captures a lot of unique waveforms. When viewing the data raw, it can therefore appear to be a bit noisy. But a closer examination of the data will reveal a real variation of the magnetic field which is caused caused by the power distribution network. Proper filtering is required to reduce the power line caused variations and reveal the strong signal of interest. It is not obvious that 60 or 50 hertz electromagnetic radiation is real, since in ordinary experience any power line “noise” is electrostatically coupled into a system (think 60 hertz hum on a stereo system) and is a fault that needs to be fixed. In this case however the variation in the magnetic field is induced by the power grid and is real. The magnetometer is simply and dutifully reporting the variation. These power line variations are to some extent present everywhere – even miles from the nearest power line. But obviously being close to power lines will increase the amplitude of the variations a lot. Often on a MagArrow survey the power line variations will be larger at one end of the survey area than the other. Poking in the GPS coordinates at the survey area nearest the larger variations into Google Earth will usually reveal the power lines from an aerial view – even if they are not visible on the ground. After applying a Fourier Frequency Transform on the MFAM data to identify the noise sources, 50 and 60 Hz noise amplitudes are easily observed. Also observable is the likely to be 20.8 Hz Schumann resonance of the third node and some other ultra-low frequency electro magnetic radiation produced naturally by the Earth. Harmonics of 60 Hz are also present. Another common question is “Why is the power line variations not a sine wave like the power line voltage?” Remember that voltages do not make magnetic fields. Only current generates magnetic fields, and the current being drawn is not a sine wave at all. Many loads, for example, only draw current at the voltage peaks. This makes for a non-sinusoidal magnetic field that is rich in harmonics. Also note that most power distribution system use a 3 phase topology. The ripple current in such a system will be 150 or 180 Hz. Thus you will often see large peaks in the power spectrum at these frequencies and their harmonics. | |||||
| How to bulk process MagArrow magdata files? | 3 Relevance | 1 year ago | Rui Zhang | Software | |
| If you have many .magdata files to convert, it is more convenient to use the command-based MagArrowConverter, instead of the Windows-based Survey Manager. The MagArrowConverter installation file can be downloaded from this link: Attachment : MagArrowConverterInstaller-2.2.129.0.zip To use the MagArrowConverter: Run “MagArrowConverterInstaller.exe” to install the converter. It is recommended NOT to install the converter on the default C:\Program Files\ directory since some computer may not allow users to create files in this directory. Open Windows Command (“cmd”) and enter the directory where the converter is installed. Type MagArrowConverter and press Enter key. A short instruction of how to use the converter will be printed out. If you run it from a different directory, Type the full path, e.g. "C:\ Geometrics\MagArrowConverter\MagArrowConverter" (assuming the program is installed in C:\ Geometrics\MagArrowConverter\ directory). Note that to change the installation directory, you will have to un-installed the program first and then re-install and set up the directory. A typical example command: …\MagArrowConverter Type=MA1 format=csv1 input=”C:\test\test.magdata” output=”C:\test\test.csv” decimation=10 A new csv file with sample rate of 10Hz will be created in C:\test directory from test.magdata file. After you become familiar with MagArrowConverter command, you can write a simple Batch Script to bulk process MagArrow .magdata files. An example batch code which searches for .magdata files in "C:\MagArrowData" folder and converts all files to .csv files at 10Hz is attached below. Attachment : batch example.zip | |||||
| How to change screen brightness on Panasonic Toughpads | 2 Relevance | 2 years ago | Magnetics SW | MetalMapper | |
| To change the screen brightness on a MetalMapperII Panasonic Toughpad: 1) If you want to Type easily, plug a keyboard into the USB socket in the side of the toughpad. Otherwise, use the screen keypad. 2) Open a terminal window (using the Applications menu). 3) Type the following command: sudo bash -c "echo 892 > /sys/class/backlight/intel_backlight/brightness" You will need to enter a password, which is the default password for the standard user. To set different levels, replace the number 892 with other numbers. 892 is the maximum number allowed; lower numbers will result in a dimmer screen. The change should take place immediately. Then close the terminal window and return to normal use. | |||||
| What are the system requirements for SCS Seismodule Software? | 2 Relevance | 2 years ago | Gretchen Schmauder | Software | |
| The OS software requirements are provided which each release of the software when filling out the ECR/ECO. Those requirements depend on the version released. Over the last 25 years these requirements have changed. The software only supports Windows. We do not support Linux. The last version of the SCS software support all 32-bit and 64-bit of Windows since Windows 7. Windows servers are excluded, since they have not been tested, but should work. The hardware requirements are more complicated as it depends on the Type of seismic survey, number of channels and software product SCS (SGOS, MGOS, ESOS, ...), SAS and options. It also depends how many network cards are needed, sample rate, and record length. For small systems, SCS will require at a minimum 512MB of free memory. For large systems up to a Maximum of 2GB of free memory. The CPU follow the same pattern. Any CPU since Pentium 90, if supported by the OS, will work for small systems. A bigger survey system and continuous recording software may need i5 or i7 Type CPU. An SSD drive may also be needed. See SCS software license agreement. | |||||
| How fast do seismic waves travel and what controls this? | 2 Relevance | 2 years ago | Gretchen Schmauder | General Seismograph Info | |
| Different Types of seismic waves travel at different velocities through any given material. In addition, different materials have different seismic properties, meaning that any one wave Type can have a wide range of velocities, depending on the material properties. For instance, the p-wave velocity of shale can range from 800-3,700 m/s. Granite can range from 4,800-6,700 m/s. Because of this, by themselves, seismic velocities alone are not particularly diagnostic with regard to rock Type. Ultimately, seismic velocity depends on the density and elastic properties of the material, whatever its composition. Specifically, Compressional-wave velocity depends on the “incompressibility” of the material, as embodied in the bulk modulus. The higher the bulk modulus, the less compressible the material, and the higher the p-wave velocity. Sound travels through water about four times faster than it does through air. Similarly, shear-wave velocity depends on the rigidity of the material, or the resistance to shear. The higher the shear modulus, the higher the s-wave velocity. Mathematically, where K = bulk modulus µ = shear modulus ρ = density Note that Vp depends on both the bulk and shear modulus, while Vs depends only on the shear modulus. This observation implies two things: Shear waves always travel slower than compressional waves through a given material. Materials with zero rigidity – i.e., fluids – do not carry shear waves at all. Therefore, the absence or presence of groundwater has no effect on the shear wave velocity. It is interesting to note that, in general, seismic velocity increases with density – denser rocks tend to be much harder and faster. Yet in the above equations, density is in the denominator. This is known as the “velocity-density paradox”, the answer to which can be found in the fact that the elastic moduli tend to increase with density as well, and at a faster rate. | |||||
| Use and Care of G-857/G-858/G-859 Batteries | 2 Relevance | 2 years ago | Gretchen Schmauder | Hardware | |
| The batteries used in the portable magnetometer instruments are lead-acid gelled electrolyte batteries. The choice of this Type of battery was dictated by their non-magnetic internal construction. We “magnetically compensate” these batteries to further reduce their magnetic signature. We do this with bucking coils which are mounted against the battery surfaces and then an external wrap applied. The batteries should be charged using the charger furnished with the instrument. These chargers are fully automatic and designed to do the best job of charging and maintaining the batteries for long life. All of the chargers are equipped with lights indicating when the battery is being charged and when the charging cycle is completed. The battery packs will provide the most operating cycles when they are fully charged after each use. The number of operating cycles can vary from 250 cycles to above 1000 cycles depending on how deep the discharge was and how soon the battery is charged after use. A 30% discharge per cycle may result in a lifetime of 1000 cycles or more, whereas a 100% discharge per cycle can result in only 250 cycles. As a rule the magnetometer will shut down when the battery is discharged to about 20% of full voltage. This is to ensure proper shutdown of the instrument. It is very important to recharge the battery as soon as possible after use so the maximum life can be expected from the pack. If the discharged pack is left to charge “when we get back from the field” the pack can suffer from “sulphation”. This is a high-resistance buildup in the battery which may render the battery unusable. If a battery of this Type must be stored for an extended period, it must be stored in a fully-charged condition. If such a battery is stored discharged and subject to below-freezing conditions, it is likely to freeze and be subsequently unusable. All Lead-Acid batteries must be maintained when in storage. This means that the user must recharge each pack at least once a month. Lead Acid batteries will self-discharge due to stray internal resistances, causing very small drain currents. Thus the maintenance requirement for monthly recharging is critical to long battery life. Do not leave the charger on all the time during storage. Also it is very important to use discharge the batteries on a regular basis otherwise the lifespan will be severely shortened. For more information contact our Support Department. | |||||
| Choosing the Right Lithium Polymer Battery for your MagArrow | 2 Relevance | 2 years ago | Gretchen Schmauder | Hardware | |
| The MagArrow uses a 3 cell Lithium Polymer battery to power the MagArrow during surveys. The two main requirements for the battery are that it must fit into the battery compartment, and it must be nonmagnetic. Non-Magnetic Batteries: Some Types of Lithium Polymer batteries are extremely magnetic. This is because the cell-to-cell connections are made with nickel strips (nickel is extremely magnetic). This makes them unsuitable for use in the MagArrow since they will interfere with the background magnetic field that is being measured. Whether or not the batteries are magnetic is not something that appears on the data sheet, so it is important to choose batteries of a particular construction form factor that in practice has been shown to have a very low magnetic signature. Examples of this battery Type will be shown below. There are many brand names for this battery Type, and the brand names seems to change frequently. Evaluating the Magnetic Properties of a Battery: Batteries should be measured for magnetic signature before using them. This is especially true when trying a new battery brand just to be sure the battery is not going to affect the survey data. To perform this test you will need to start a survey with a stationary MagArrow pointing north-south on a nonmagnetic platform (wooden sawhorses, cardboard box, etc). Hold the battery to be tested immediately over the battery compartment and rotate it in all orientations. Download the data and look for variations in the magnetic field that correlate with the battery rotation. There shouldn't be any correlation above 1 nT peak to peak. Make sure the operator is nonmagnetic when doing this test (shoes, belts, watches, cell phones, keys, etc. can all corrupt the results). Battery Size and Shape: The correct batteries are rectangular in shape and measure roughly 105x34x24mm. They are made from 3 flat cells stacked up measuring 11.1 volts nominal. They should be between 1800 and 2200 mAh (milliamp-hour). Higher capacity batteries will not physically fit in the battery compartment. Lower capacity batteries will work, but with a reduced run time. One 1800 mAh battery will run the MagArrow for about two hours. The MagArrow power connector is XT-60 so the battery must match. There are other power connector Types, but XT-60 is commonly used. The 4-pin balance port connector is a JST-XH4 connector (though this is standard on most batteries). Where to Find Batteries: If you are in an area that doesn't have strict controls on shipping Lithium Polymer batteries, then Amazon.com is a good source. Another good source is hobby stores, or anyplace that sells radio-controlled toy cars, boats, or airplanes. This is typically where this style of battery is used the most. What do the Battery Specifications Mean? 3S: This means it is a stack of three Li-Po cells Voltage: A fully charged 3 cell Li-Po battery measures 12.6 volts. A depleted battery will measure 9.6 volts. Thus, the voltage for this battery is typically labeled as 11.1 volt (the average of 12.6 and 9.6 volts. 35C (or any other "C" value): This is a rating on how much current can be safely drawn from the battery. To get the value in amps, take the milliamp-hour rating and divide by 1000 (to get amp-hours), and then multiply by the "C" value. For a 2200 mAh battery with a 35C rating multiply the 2.2 amp-hour capacity (2200 mAh / 1000) times the C value of 35, which gives a maximum discharge current of 77 amps. The MagArrow draws about 0.6 amps, so any C value is fine - even if is down to 0.5. Battery Chargers: Most battery chargers being sold now are universal chargers which support a variety of rechargeable battery chemistries and output connectors. They come in many sizes and shapes, but most of them operate identically because the internal circuitry is the same. Most chargers will charge at a much faster rate than the MagArrow discharges them, so you technically only need two batteries in the field. A nice feature to look for is the ability to power the charger off 12V as well as with AC power. This will allow charging in the field off a car battery. Be sure to charge in batteries in "Balanced Charge" mode using the battery balance JST-XH connector. This allows more charge current into cells that are more deeply discharged than the others and ensures that the battery gets all three cells completely charged. Battery Safety: Lithium Polymer batteries are small and light but store a tremendous amount of energy inside. This is good for running equipment for long periods of time between charges, but it also means that if something goes wrong and it releases all its energy at once it can be a serious fire hazard. Never charge a lithium battery unattended, charge only in a fireproof location. Batteries that are swollen or damaged should not be used. Dispose of these per local regulations. Be sure to follow all regulations for shipping or hand carrying Li-Po batteries. This may include packaging and labeling requirements, limiting the number of batteries, and discharging the batteries to 30% capacity before shipping. Do not discharge the battery below 9.6 volts (3.2 volts per cell). This damages the battery and could result in destructive decomposition and fire. If a battery that is discharged below a safe level is placed on the battery charger it will refuse to charge it. Batteries that are discharged below 9.6V should be removed from service and disposed of according to local regulations. To download a copy of this document as a PDF, click here. Some example batteries are shown below: | |||||
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