Additional comment about the “spur” / DC spike:
I also read through this post, dealing with the “spur” / DC spike of the PlutoSDR oscillator and SATNOGS_LO_OFFSET parameter.
It seems like, that some of my parameters are not set correctly. The standard value of the SATNOGS_LO_OFFSET is 100e3 and shall be well within the sample-rate. Currently, I am using a sample-rate of 2e6 and the standard lo-offset (100e3). Therefore, the DC spike is present on the wider waterfalls.
I will change for both setups (UHF, S-Band), running with a sample-rate of 2 MHz, the lo-offset to 5e5 (0.5 MHz), which should solve this issue - similar to sample-rate = 8e6 and lo-offset=2e6 as stated in the post.
Often the sample-rate and bandwidth are assigned with the same value, e.g. both 2e6. Do they need to by equal or can they be different?
Nevertheless, this will not fix the off-center frequency.
Cheers,
Alex, oe3ala