DiX wrote:
The problem is I have to use relatively high bit rate on these tx and rx
paths. The demic rate should be <=16, and interp rate <=32. When I run the
code with decim rate = 16 interp rate = 32, I keep receiving uO. My
questions are : what's the max rate the USRP can support in this case? and
is there any fatal fault in my graph design?
Hi Di,
uO means that the USRP is overrunning, in other words your host machine
cannot keep up with the incoming data rate.
The USRP cannot keep up with more than 8Msps due to the USB bus
limitation with 32-bit complex. You will get overruns if you try
anything more than this. Let's take the case of a single
daughterboard... you will not be able to use a decimation rate lower
than 8 (64Msps/8 = 8Msps).
The first thing to do, is to check to see if your machine can keep up
with 8Msps. Run "./usrp/host/apps/test_usrp_standard_rx -D 8" and see
if you get any uO. If not, keep increasing the decimation until you get
no uO.
Since you're using two RX chains, with a decimation rate of 8, you'd be
generating 16Msps since each chain generates 8Msps. Therefore, when you
say "decim rate should be <=16" ... <=16 is not possible, only =16.
With decim=16 you're generating 4Msps per chain, for a total of 8Msps.
- George
_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
