GPS Jamming #2

A few days ago I got a RTL-SDR dongle to play with and I thought to give it a shot and measure the interference levels coming form the raspberry pi camera.

This is what I got around the GPS L1 frequency.

 

Camera off:

Screenshot from 2016-01-24 16-04-05.png

Camera on:

Screenshot from 2016-01-24 15-58-54.png

Notice the 2 peaks at 1,574.996 Mhz of -68db and 1,576.468 Mhz, -70db. They are very close to the GPS L1 frequency of 1575.42 Mhz and I’m sure the are the cause of the interference.

The big issue is that they radiate a long distance around the quad, dropping by about 10db 0.5m away from the quad. The pattern is not uniform, there are gaps where the interference disappears and I assume it’s due to reflections.

Note that changing the resolution and bitrate of the camera doesn’t change anything…

 

Next step – since I can now measure it – is to see how I can eliminate it.

A few options come to mind:

  • tin foil (although last time I tried this there was no change)
  • replace the flex cable with a shielded hdmi cable
  • replace the camera with another one? Not sure if this will change anything
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