Observation 1047661: BHUTAN-1 (43591)

Regarding Observation 1047661

Any thoughts on what is causing this striping?

Some things I have already eliminated:

  • FM band reflection/interference (installed FM bandstop filter)
  • Undervoltage (have good power supply and cable, no undervoltage detected anymore)
  • LNA (have tried several LNAs, including the RTL SDR blog wide band)
  • Bad SDR (have swapped out w/ three different brand new RTL SDR v3s)
  • LED lightning (all power to LED lighting has been cut all day)

I don’t see this striping on the 2m birds, just these 70cm ones.

Unfortunately it is most likely either overload/intermod from other nearby transmitters.
400-500 MHz is a commonly used land-mobile band and it’s quite common to find repeaters and other transmitters which may push your LNA+RTLSDR into saturation.

It might be worth having a scan around 400-500 MHz (maybe using something like rtl_power, or GQRX) to see if you can find any obvious strong signals that may be giving you grief. If this is the case, then your only real solution is some kind of band-pass filter, possibly installed between the antenna and the LNA.

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If you have another receiver, it would be good to set-up fully independent of the SDR experiencing the interference. If possible make portable with a battery powered set-up, so it’s not connected to the house wiring. This will allow roaming with the second receiver to do some direction-finding for the Radio Frequency Interference and confirm it’s not something with the power source allowing input through the house wiring.