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Re: [Discuss-gnuradio] a report on dqpsk modulation in gnuradio
From: |
Stefan Brüns |
Subject: |
Re: [Discuss-gnuradio] a report on dqpsk modulation in gnuradio |
Date: |
Tue, 09 Dec 2008 17:25:11 +0100 |
User-agent: |
KMail/1.9.9 |
Hi,
just a different suggestion - have you tried to determine if there is a
frequency offset between the receiving and the sending USRP? I did some tests
with the digital/benchmark_?x.py / qpsk code before the recent changes, but
for me it worked quite well when I adjusted the center frequency of the
transmitter or the receiver by their respective offset, eg:
./benchmark_tx -f 2.40001e9 ...
./benchmark_rx -f 2.4e9 ...
To measure the offset, I built simple flowgraph with a constant value as a
signal source, which gives just a carrier, which should be (in an ideal
world) at the selected center frequency, visible e.g. in usrp_fft.py
Hope this helps,
Stefan
--
Stefan Brüns / Bergstraße 21 / 52062 Aachen
mailto:lurch at gmx.li http://www.kawo1.rwth-aachen.de/~lurchi/
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