Sunday, November 16, 2014

Beaglebone Black & RTL Dongles Used Drive Testing Power Line Noise

So I've already mentioned before that I wanted to use some very inexpensive equipment to perform some Drive Testing experiments.  Basically I want to measure Noise Floor in 4 Ham Radio Bands (50 Mhz, 144 Mhz, 222 Mhz, and 432 Mhz) while I drive all around Town.  While this is happening I want to record GeoLocation for each reading logged, and plot on a map where the worst areas are, so that I can then return to those areas and try to hunt down the sources of the noise.

NOTE: all that's really left is to calibrate the NF measurements (obviously -78db and -34db reading aren't valid, but a little calibration and it'll be good to go)

I have the basic's of this system working now!  I haven't actually done any drive testing yet, but I intend to very soon.

My experiments so far from home are very encouraging!

I've built a little Web interface which displays things like:

  • System Load (of the beaglebone black)
  • Disk space usage (of the beaglebone black for a mounted SD card which I store logged data to.
  • There is a basic control panel which lets me start/stop the GPS, and Various attached RTL dongles.  This process also moves logs to archive them when these processes are stopped.
  • There areas in the web UI which show me GPS data logged, RTL Noise Floor measurements as they are made (live).
  • There is a Google Map API which plots the Lat/Long and Noise Floor measurements for the recorded data.  This allows me to then return to areas where Noise measurements where high.
My current GPS has a fair amount of 'drift' however it doesn't seem to exceed about 50 feet from the actual position.  And for my initial test runs of this this is perfectly acceptable.  Since this is still proof of concept. This gps only cost about $38.00 USD.  So nice and cheap.

I have a Jackson Labs "FURY" GPS which cost me $380.00 some years ago, and is WAY more accurate.  I intend to use that eventually.  That should be FAIRLY simple!  I just need to get a snap-on Serial Port for the Beaglebone black, or a USB/Serial port to connect it up.  And 'gpsd' should work with it just fine.

Anyway I wanted to post that I've been busily working on this the past week or so.  And today I can report I have 100% success on getting everything functional enough to begin actual drive testing within a week or so.

I'll post some video's of what I have currently running, as well as some still photo's of how it all is connected up soon.





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