I don't know if it is relevant at all.
If I read right the SDR can have a GPS sync for precision control of the ADC clock, maybe just maybe its is trying to do that loop in the background without a gps sync which might, might cause the ADC clock to wander a little.
I did swap out ntpd for chronyd but i did not take the time to set it up for GPS PPS sync, as I was and am not sure if the open web rx software needs to control any of that.
This is ntp sync status:
Code:
210 Number of sources = 4
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
^+ 159-196-3-239.9fc403.mel> 2 10 377 180 +1231us[+1231us] +/- 34ms
^* time.cloudflare.com 3 10 377 775 -4621us[-6698us] +/- 14ms
^+ bitburger.simonrumble.com 1 10 277 14 -2577us[-2577us] +/- 21ms
^+ 14-202-65-230.tpgi.com.au 1 10 377 308 -3799us[-3799us] +/- 26ms
Reference ID : A29FC87B (time.cloudflare.com)
Stratum : 4
Ref time (UTC) : Sat May 17 01:10:44 2025
System time : 0.001697727 seconds slow of NTP time
Last offset : -0.002077176 seconds
RMS offset : 0.002063389 seconds
Frequency : 6.657 ppm fast
Residual freq : +0.001 ppm
Skew : 0.111 ppm
Root delay : 0.025742332 seconds
Root dispersion : 0.003906695 seconds
Update interval : 1040.1 seconds
Leap status : Normal
As you can chrony picked the stratum 3 source not the 1's.
also a note on bandwidth. the water fall seems to an average take 100KiB/s / per user.
and to date we have used 1.13GiB upload and 159MiB download with respect to the modem.
here is a pic of the MW band last night. I didn't know that there were still that many stations.

I've never heard 621 as good.