Consider we have QPSK signal with carrier frequency 10kHz. Generally, we demodulate or use matched filter on the the QPSK signal and recover the transmitted bit or the symbols. If the QPSk signal is noisy can we use band pass filter before demodulation, where the pass band is around 10 kHz? The QPSK signal has discontinuity when the bit/symbol changes, so are we going to loose valuable information if we band pass the signal before matched filter? Is there an appropriate band width of the band pass filter which can be applied so that matched filter still works after the band pass filter?
EDIT: More importantly can a band pass filter prior to matched filter show better results? If so under what conditions?
This question is also asked in: https://dsp.stackexchange.com/questions/59079/can-we-band-pass-filter-qpsk-signal