Add frequency correction (NCO/PLL) capabilities

[SignalWhisperer]

Is your feature request related to a problem?

I'm trying to use URH to debug my client's satcom protocol. The terminals in use are old and do not transmit at a constant power, neither do they transmit right on the expected frequency. For the power, it's acceptable within URH (good SNR), but since it uses QPSK modulation and they are a little bit off of the center frequency, URH is completely unable to decode the QPSK (PSK with 2 bits per symbol) signal.

Describe the solution you'd like

There might already be a way, but I can't find it anywhere. I need a way to add frequency correction (NCO/PLL), ideally from within URH.

Describe alternatives you've considered

I did consider pre-processing the signal before feeding it to URH. This is a lot of extra effort and nullifies the gain of using URH in the first place. It also makes recording live signals useless since you'd need to record it in URH, save it to a file, process the file with the external tool, then load it right back in URH.

Additional context

URH works great for FSK and ASK, but PSK requires the frequency to be corrected through the use of a PLL to prevent rotation of the constellation. URH does not seem to offer any means of frequency compensation and thus any recording of a M-PSK signal is useless within URH if there is any frequency offset.