FM Radio Interference?

Regarding Observation 4704538

What’s going on here? I have an FM BPF and am still getting FM radio interference on my ground station.

Currently, I have the BPF behind the LNA, I have tried swapping them and it makes no difference. Any advice is appreciated

1 Like

If you are using a LNA, then your receiver gain is set way too high, which will exacerbate the intermod issue.
A ‘nominal’ starting point for a system with a LNA out front is ~30db of gain, but it depends on your situation. The ‘Setting the gain’ guide can help find a suitable optimal gain value: Omnidirectional Station How To - SatNOGS Wiki


BPF should be definitely before the LNA.

  1. It is necessary to check the settings, as vk5qi proposed.
  2. Also, what is behind, the total scheme? It might be the second BPF is necassary.