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From: | Einar Thorsrud |
Subject: | Re: [Discuss-gnuradio] GNU Radio and USRP baseband demodulation/decoding |
Date: | Thu, 05 Feb 2009 19:59:55 +0100 |
User-agent: | Thunderbird 2.0.0.19 (Macintosh/20081209) |
Johnathan Corgan wrote:
Carrier recovery/synchronization can be done with a Costas loop, which will track out any residual carrier resulting from not being tuned to exactly the center frequency of your passband. For symbol timing, there is a resampling block implementing the Muller and Muller algorithm. This will track the "center of the bit" and fractionally resample to 1 sample per symbol. This is a common enough combination that there is a combined block to do both with less CPU consumption and better SNR (gr.mpsk_receiver_cc).
I have been studying digital-bert example files, and will try to do something similar. However I have a follow up questions. How will the synchronization and carrier recovery function on my baseband signal as there really is no carrier left after the down conversion? My specific signal is down converted from 5.8 GHz to baseband from an RF front end, which is not controlled by GNU Radio at all. Would the blocks you mentioned function with the baseband signal if the center frequency is specified to be 0 Hz?
Welcome to GNU Radio!
Thank you! :) -- Einar Thorsrud
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