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RE: [Discuss-gnuradio] GNU Radio and USRP baseband demodulation/decoding
From: |
Tachwali, Yahia |
Subject: |
RE: [Discuss-gnuradio] GNU Radio and USRP baseband demodulation/decoding |
Date: |
Thu, 5 Feb 2009 21:49:03 -0600 |
Hello Einar,
Knowing your modulation type can simplify your symbol and carrier
synchronization design. However, if your are not restricted with certain
modulation type and you just want to use an arbitrary modulation to get you
going then I suggest to use differential coding such as D-BPSK which does not
require coherent detection (no carrier synchronization is required) and that
can simplify your design.
I hope that help a little. If you are really after symbol synchronization, I
have read several publications by Dr.F.Harris and Dr.C.Dick but they tend to do
their implementations in FPGA.
Kind regards,
Yahia Tachwali
________________________________________
From: address@hidden address@hidden On Behalf Of Einar Thorsrud address@hidden
Sent: Thursday, February 05, 2009 5:42 AM
To: address@hidden
Subject: [Discuss-gnuradio] GNU Radio and USRP baseband demodulation/decoding
Hi all,
I am trying to use the USRP with the LFRX daughterboard to receive a
baseband signal coming from an external RF-frontend (the signal is
originally 2-PSK passband). I am a GNU Radio novice, and have some
difficulties understanding how to synchronize to and decode the
NRZI-coded baseband signal. I suppose ones the synchronization is done
the actual decoding will be easy.
I find it difficult to understand the process of synchronizing, what I
would like to see is some kind of guide or feedback on how to pick
exactly the correct number of samples for each symbol, enabling the
decoding of the signal symbol for symbol.
What would be the correct approach to solve this problem?
(I am in fact also having similar problems understanding this using the
OSSIE SDR system, so it may be a more general lack of understanding on
my behalf)
--
Einar Thorsrud
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