Software - Geometrics Forum

How to bulk process MagArrow magdata files?

Rui Zhang — Thu, 21 Nov 2024 15:40:09 +0000

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 MagArrow product link under firmware/software download:

https://www.geometrics.com/product/magarrow/

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.

Why are there more columns than headers in CSV data files?

Rui Zhang — Wed, 09 Oct 2024 01:16:29 +0000

Every second, the NMEA strings, delimited by single quotation marks, are included as separate columns. The strings also contains commas. Therefore, there will be more columns if you use comma as the only delimiter.

The correct import setting should be comma-separated, with single quotation marks as string delimiters. All of those "extra" columns will be revealed as the original RMC and GGA NMEA strings.

For a low-noise MagArrow, how to check whether it is set to the low-noise mode or the low-heading mode?

Rui Zhang — Fri, 09 Aug 2024 16:47:38 +0000

If you purchase a low-noise MagArrow (I or II), the factory default is the low-noise mode.

You can also look up the current running mode by loading the following website (in Instrument Status) after connecting to the MagArrow:

192.168.1.1/systemtest.cgi

To switch to a different mode, please download the special software below and follow the instructions in the readme file:

Please note that even in the low-noise mode, the heading effect is typically only ~20% worse than that in the low-heading mode. For most applications, you don't need to switch to the low-heading mode.

Software Update April 8, 2024 - Anomalous Behavior in the GPS

Gretchen Schmauder — Thu, 11 Apr 2024 22:42:27 +0000

What does different Sensor Modes represent?

Rui Zhang — Wed, 13 Sep 2023 19:45:50 +0000

There are 3 different Sensor Modes: Heating, Locking and Normal.

Heating and Locking are stages during startup. Heating means the Cs cell is warming up and Locking indicates the laser locking (frequency/wavelength stabilizing) stage.

In room temperature, Heating should take less than 5 minutes and Locking less than 10 minutes.

If the startup time takes much longer than expected, please check the error code displayed on http://192.168.1.1/status.cgi (and click “Detailed Instrument Status”).

How to convert MagArrow SD card files to CSV (or GDB) files?

Rui Zhang — Tue, 22 Aug 2023 01:37:20 +0000

In case that the WIFI connection fails after your survey and you cannot download .magdata files via WIFI, you can remove the SD card from the MagArrow and copy raw survey data to your PC. To convert raw files to CSV files, please follow instructions below:

The instruction for the latest survey manager can be found here:

https://www.geometrics.com/wp-content/uploads/wpforo/attachments/72/147-MagArrow-SD-card-Data-Conversion-latest.pdf

The instruction for earlier version of survey managers can be found here:

https://www.geometrics.com/wp-content/uploads/wpforo/attachments/72/37-MagArrow-SD-card-Data-Conversion.pdf

Geometrics preliminary MagArrow and MagEx data processing program download

Rui Zhang — Fri, 04 Aug 2023 22:41:28 +0000

The zipped files can be downloaded here:

After unzip, please keep all files and folders!

Before you run the program, please download and install the LabView Runtime (free, 64-bit 2020 SP1) first:
https://www.ni.com/en-us/support/downloads/software-products/download.labview-runtime.html#369642

The user guide is located in the folder.

It is worth mentioning that the data processing program provides 2 methods of suppressing the survey noise:
1. Through frequency filtering and line levelling (Survey Data Noise Reduction).
2. Heading effect compensation (Heading Error Compensation).

In general, to perform the heading error compensation, you need to collect heading effect calibration data (Instruction included in the folder).
It is possible that the calibration data can be obtained from the survey data itself.
If you have trouble processing your data, please share some of your data with Geometrics and we can provide help, especially in generating the calibration file.

If the trial version expires, please replace the configuration file inside the Config Files folder with the new one below:

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Importing Raw Data From the MagArrow

Gretchen Schmauder — Fri, 21 Jul 2023 17:43:29 +0000

Raw Data

MagArrow data is imported into Survey Manager in the form of .MAGDATA files, downloaded from the MagArrow. The .MAGDATA file contains measurements from different sensors inside the MagArrow: 1000Hz magnetometer readings; accelerometer, gyro, compass, temperature readings; and GPS info.

MFAM assigns a fiducial number, or “FID” to each magnetometer reading, in a cycle from 1 to 1000 that repeats every second. In the instrument, the magnetometer readings and the GPS sentence data are synchronized so that the “FID-1” magnetometer record is matched with the GPS location and timing information. Exports to CSV and Geosoft file formats
1000Hz un-filtered export
The 1000Hz export provides the original raw magnetometer data plus some simple interpolations: • Magnetometer reading: The raw magnetic field values are exported without application of a filter. • Auxiliary sensors: Gyro, accelerometer, and temperature are acquired once per every 5 magnetometer readings, and are reported only when acquired. Compass readings are acquired one per every 10 magnetometer readings and are reported only when acquired. • GPS NMEA sentence: Reported with the associated FID-1 mag record. A few individual fields from the GPS are also broken out from the GPS sentence and reported separately, without interpolation. • Interpolated GPS fields: Time, date, latitude, longitude, and track (course over ground) are linearly interpolated between GPS readings.
Decimated exports
Each of the exports at frequencies from 10 Hz to 100 Hz is a decimation – data are filtered by a low-pass filter and then down-sampled to the target sample rate. Each low-pass filter (a different one for each decimation) is a symmetric finite impulse response (or FIR) filter, with the following design goals: • -3dB attenuation at 0.75 * Nyquist frequency (e.g., the -3dB point for the 10Hz decimation is 3.75Hz) • Significant attenuation of 50Hz and 60Hz signals. • Reasonably flat response in the pass band.
Linear phase (or zero phase, or constant group delay) filters.
These filters are not Kalman filters. The filters are applied to fields in the decimations as follows: • Magnetometer readings: Magnetometer readings are decimated: the FIR is applied, then the data are down-sampled to the target rate. • Aux sensors: Aux sensors are first up-sampled to 1000Hz by linear interpolation of values between individual readings (which occur once every 5 mag readings for gyro, accelerometer, and temperature, and once every 10 mag readings for compass). Then these 1000Hz values are decimated in the same process as the magnetometer readings. • Latitude and longitude are first up-sampled to 1000Hz by linear interpolation of values between successive GPS data (once per second), then these 1000 Hz values are decimated in the same process as the magnetometer readings. • Time, date, and track are linearly interpolated as in the raw, unfiltered 1000Hz export.
Merging filtered and unfiltered data.
Some of the values in an individual line of data are filtered: mag readings, aux sensors, etc. Other measurements are not filtered: time and date, GPS sentences, record counters, and the simple interpolated fields. These two sets of values – filtered and unfiltered, must be reported in individual lines that contain values of both types. The question “How should the two sets of values be matched?” is addressed as follows:
A decimation filter has a center. For example, a single filter result that weighs 499 individual measurements running from record number 752 to record number 1250 (in DSP terms, it is the result of the convolution of 499 input values with 499 filter weights), is centered on record number 1001. The result is the “filtered value of record 1001”. In a single line along with this value should be the other filtered results centered on record number 1001 plus the unfiltered raw and interpolated values that were recorded as part of the original, raw record 1001. The down-sampling part of decimation involves keeping some results and discarding others; down-sampling from 1000Hz to 100Hz includes discarding 9 out of 10 results. During exports, Survey Manager keeps the “FID 1” record, because it includes the original GPS information, then discards the next 9 records (if it’s a 100Hz decimation), and then repeats the pattern, each time starting with FID 1.
If you have questions about the MagArrow decimations, please contact your Geometrics account manager.