Channel 0 Noise Spurs at +976.025 kHz of baseband

1

Hello,

I’m using GNU Radio to pull the five KrakenSDR channels individually, and I’m seeing a strong spur/birdie on channel 0 only at +976.025 kHz relative to the tuned center frequency (I tested 433 Mhz, and 915 Mhz, and stepped up 916, 917 and 918, noise was identical in the same location in every band).

It also has spurs/combs at approximately the following frequencies:

  • +/- 16.003 kHz
  • +/- 9.375 kHz
  • +/- 6.628 kHz

And it continues, especially up the spectrum.

image
image1535×896 50.7 KB

A few questions:

  1. Is this a known KrakenSDR artifact?

  2. Does this suggest that something is wrong with my unit, or is this within expected behavior?

  3. Is this from internal calibration/noise source or switching/control circuitry?

  4. Is it safe to notch/blank this narrow spur on channel 0 for downstream visualization/detection?

  5. Would notching channel 0 only cause issues for coherent/DOA processing or calibration?

I am assuming this doesn’t mess with DOA too much (cross-channel coherence is low, mostly < 0.15), but I’d like to know whether this is a normal workaround or whether I should be investigating a hardware issue.?

I’ve attached a spectrum plot showing all five channels. Channel 0 is the blue trace.

Regards,
Aeonik