CPFSK grc block question problem with data types

GNU Radio
1

Hello all,

I am having the following trouble with data types:

I have the following flowgraph working to record FM broadcasts:
{USRP2 source -> LPF -> FM Demod -> File Sink}

Next, I am making another program to transmit the stored FM broadcast
audio to my handheld radio which expects FSK modulation. So I would like
to do the following:
{File source -> CPFSK mod -> LPF -> USRP sink}

The problem is that the grc CPFSK block expects bytes. This means that
the recorded file has to have bytes, but the FM demod only outputs
complex or float data types. Is there a gnu radio function (or grc
block) that converts floats to bytes? Or is there a way to store the
audio data as bytes in my first program?

Thanks in advance for your help,
Mike

2

The CPFSK block expects digitally encoded data as bits. The file sink
will give you raw demodulated samples. You need to determine what format
your handheld radio expects to see before you can re-encode your saved
data appropriately. FSK describes a digital modulation scheme but says
nothing about the packet or stream format the radio expects.

–n