[Discuss-gnuradio] Designing a good receiver

[Mike Clark]

This comes from a discussion over on the USRP-users mailing list, but
I felt it would be more appropriate to post here. Over on that list,
someone was asking about problems they were having consistently
receiving data on their USRP. My background is in CS, not RF comms, so
please forgive me as I'm sure the answer will be fairly standard :)

Anyways, the question I have is, is there a general procedure one can
follow to design a decent receiver in gnuradio? For example, I have a
project that I'm using for experimentation where my receiver looks
like this: USRP Source -> GMSK Demod -> Packet Decoder -> File Sink.
This works well when I have the USRPs cabled together and even when I
have antennas with line of sight (I haven't checked max distance).
When I don't have line of sight, however, I stop receiving packets.
Are there any other gnuradio blocks I can add in to my setup which
will help get better performance when there is no line of sight? I
haven't tested it, but my guess is that when there is no line of
sight, there must be a frequency shift or something of that nature
happening which ruins the connection.

Mike