[Discuss-gnuradio] Problem with 8-bit option and dropped samples
From:
Lisa Creer
Subject:
[Discuss-gnuradio] Problem with 8-bit option and dropped samples
Date:
Mon, 20 Aug 2007 23:15:36 -0400
I'm testing the -8 option in various example programs, and haven't been
successful in receiving valid data. The following test resulted
in a very brief, flat line being displayed, then absolutely no data
showed on the graph, but the program continued to run.
./usrp_fft.py -f 100M -d 4 -8
format = 0x288
set_format = True
I decided to try decimating by 4 without specifying the 8-bit option,
and I received the 'uO' indicating that samples were dropped from the
USRP to host, but data was displayed on the graph, and it was 16MHz
wide. What's going on?
./usrp_fft.py -f 92.7M -d 4
uOuOuOuOuOuOuOuOuOu
I've also written a data capture script that simply writes data from
the USRP to a file, and when I use the usrp.source_s () function (after
using make_format, set_format) I get a few initial non-zero bytes, but
the rest of the data file is zeroed out.
Any idea what is happening here? I'm wondering if my signal is so weak,
that the 8-bit option is truncating all the data off. When running
usrp_wfm_rcv.py I can only get one strong FM radio station.
Other questions are:
Is the 'uO' the only indication that samples have been dropped?
Does the number of 'uO's correspond to the number of samples dropped?
What are the buffer sizes?