Is there any good matrial avialable for data specific DSP? I have gone through some great DSP intros for beginners in python but all of them revolve around the characteristics of audio signal
With SDR, you actually create / process the signals that carry your data over the RF medium.
Therefore, to an extent, "freshman level theory" is all you are stuck with if you have to write an end-to-end SDR system.
But, you could keep the book (or, a book) as a reference for points you don't understand when going through something like GNU Radio's PSK Demodulation resources for example.
I am not sure what your expectation is from SDR, but taking the comment (about SS7) as a starting point, it's not like the SDR has an API which you use to simply "send data". Although, I am sure that you could add that layer too once you have your basic DSP dataflow set up.
The beauty of SDR is that you take full control of every building block from transmission to reception. So, there is nothing stopping you from writing a Phase Locked Loop (which you are going to need) from first principles or use one of the existing ones (or here).
But you still have to have some awareness of what is the "loop bandwidth" for example, in the case of the PLL.
Hope this helps