Here are some data samples produced by stribog the attitude sensor.
The logged files for 16 Apr 2006, 21 Apr 2006 are available at <URL:http://download.savannah.nongnu.org/releases/stribog/25v6-stribog.data.tar.bz2>
When in a car we place the board so that x axis is directed forth, z axis to zenith.
Car generator produces specific magnetic pulses. we looked for a place where this noise is minimal. so we placed our board
The engine worked, but the car didn't move.
The board run magex, so we can see 800Hz magnetic field samples. the data can be extracted into text with magexpon.
Two files has been logged for each position: with the sound system on (*verbous.log) and off (*silent.log). we couldn't find any difference in the noise, even under the rear window, where the speakers are situated.
In the last case (under the back window) the noise is quite low. it may be said the car makes no noise at all. unfortunately, there appear significant vibrations when she runs.
Some graphs made with gnuplot follow (sample frequency 798.4Hz assumed):
magex shows 50Hz cycles in an electrified building.
The cycles are evidently not sinusoidal:
Here some more graphs for magnetic measurements.
The board was mounted under the back chair. on the roof we placed a GPS antenna. the GPS receiver is a Garmin GPS-25. we run multa on stribog, connected the output of the receiver to PORT0 and logged output of the board with conloq. (well, no GPS data shown yet)
In the moving car we see vibrations.
We think they are due to moves of ferromagnetic parts mostly. their amplitude is about 1 degree, which is not so bad.
These are dramatic deviations due to steel bridge construction (we moved over the river).
Such anomalies possibly can be detected by means of z-axis measurements observation.
A smaller bridge
High-voltage line crosses the road
An attempt to obtain the temperature curves of the magnetic sensors:
originally written in Russian report.pdf (205k)
These PDF files are public domain.
A brief report on field tests
Last modified: 03 Apr 2008
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