GNU Radio GFSK Modulation and Demodulation

Question

I'm brand new to DSP and I'm experimenting with GFSK modulation to eventually output the signal using ultrasound. Could someone please explain why this set up doesn't work.

I'm receiving a serialized protocol buffer on the ZMQ Pull source and I'm expecting that if I just modulate then demodulate the signal I will get the same protobuf sent, back in the process that sent it (ZMQ push source sending it back). But that ends up not being the case and the byte pattern received after demodulating is off. Could someone explain why my set up doesn't work, Thank you again.

Flowgraph of GFSK mod/demod

Answer 1

You can either use pack instead of repack or you can use repack , but change the endianness from LSB to MSB.

This demo shows both approaches: