I'm struggling with something pretty basic. I am trying to achieve near theoretical performance detection of a rectangular (no RRC) QPSK signal at 2 or 4 sps. I have an existing solution that uses a discrete FIR filter followed by a Gardner timing recovery loop. The taps of the FIR filter are a box car function. It works quite well and implementation loss is negligible.
However, I'd like to achieve the same thing using the stock PFB clock sync. For the life of me I can't figure out the proper specification of nfilts, and taps.
Given a signal with rectangular pulse shape at 'sps', can someone spell out the taps and nfilt i need to enter into PFB clock sync for a properly matched filter bank?
-John