You do not need to use throttles when using a UHD sink/source,
because the device provides timing for the flowgraph.
Remove the throttles and try again. If you still see the failure
I'd say you are not achieving symbol sync.
-John
On 04/08/2012 01:58 PM, Huzaifa Zafar wrote:
Dear all,
I am working with 3 people on a project involving GNU Radio and
USRP1. We have tried to implement a simple point to point digital
communication system in GRC involving DQPSK modulation. Using a
vector source we are sending a finite stream of zeros and ones
(the vector source has Repeat set to yes). On the receiver side,
what we receive is really very strange: The same stream of zeros
and ones, but with extra zeros in between our actual data. For
example, we send three ones and three zeros, but what we receive
is a one followed by seven zeros, another one followed by seven
zeros, another one followed by seven zeros, and then a zero
followed by seven zeros e.t.c. We tried to experiment more by
using the 'KEEP 1 in N' block and the 'DECIMATING FIR FILTER', but
things are not working out the way they should.
I am also attaching a snapshot of the .grc file for your
reference. Please tell us the reason why these extra zeros are
present between our data bits, and the way to combat this
effect (remember that the decimating fir filter and keep 1 in
N block are not showing the desired output). Any kind of help
is appreciated in advance.
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