All packets may lose when running benchmark example in gr-digital/examples/narrowband

Hi all,

When I was running benchmark example in gr-digital/examples/narrowband,
all packets may lose. The environment is shown below.
Hardware: USRP N210 with WBX
Software: GNU Radio v3.7.2.1-62-g6195ff3c and
UHD_003.006.000-0-g58f4af97

The two USRPs are placed close to each other. The example is run by:
On the TX side: python benchmark_tx.py -f 1.55G -m qpsk -r 200k -M 10
On the RX side: python benchmark_rx.py -f 1.55G -m qpsk -r 200k

Sometimes, all packets could be received. Then I restarted test, nothing
was printed in the terminator on the RX side.
It looks like a random event. I guess there is something wrong with
timing synchronizer in the receive path.
By the way, everything is ok when we do the test with gmsk.

Best regards,
Damon

On Thu, Dec 05, 2013 at 06:47:16PM +0800, Damon wrote:

was printed in the terminator on the RX side.
It looks like a random event. I guess there is something wrong with
timing synchronizer in the receive path.
By the way, everything is ok when we do the test with gmsk.

This can happen, it takes a bit of practice to transmit and receive a
clean signal. There lots of reasons this can go wrong: Interference,
non-linear distortions (wrong gain settings)…
GMSK is a bit more robust in these regards. Nothing to worry about!

MB


Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

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