[Discuss-gnuradio] GMSK receiver question, USRP tuning?

[George Nychis]

Hi all,

I'm using benchmark_tx.py to transmit a GMSK sequence at 10MHz.  As some 
of you know, I'm trying to debug my own GMSK m-block receiver.

If I use test_usrp_standard_rx -F 10000000 (not the in-band receiver) to 
capture the incoming signal and plot it, I get the graph on the top, and 
if I dump the data coming out of the usrp1_source_c block when running 
benchmark_rx.py -f 10000000, i get the bottom graph:
http://www.andrew.cmu.edu/user/gnychis/std_gmsk.png

I can successfully decode the transmission with my receiver using the 
data output from usrp1_source_c and benchmark_rx.py ... however I cannot 
decode it using the samples from test_usrp_standard_rx.

So I'm wondering, what is benchmark_rx.py tuning on the USRP differently 
than test_usrp_standard_rx?  Of course, my goal is to duplicate this 
action because my in-band code is also dumping data similar to the top 
graph.

Thanks!
George