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.
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