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From: | Bastian Bloessl |
Subject: | Re: [Discuss-gnuradio] diminishing returns with increasing frequency offset |
Date: | Thu, 24 Mar 2016 18:12:36 +0100 |
Hi,
Following your notation you would have to decrease ‘a'. Think of a moving average, implemented with a FIR filter, which averages over a certain time window. If you double the sample rate, you have to double the length of the filter to average over the same time window. Another thing you could try is multiplying the output of the subtract block by 2, when switching to 8MHz. This way, the input of the MM block would have the same amplitude (and amplitude matters). Apart from that I don’t see any obvious problems. Unfortunately, I’m not in the office to test your 8MHz flow graph :-/
After the subtract block you should have a signal that is centered around 0 and the chip sequences should be clearly visible. (The problem is that the trigger doesn’t work for the phase.)
Thanks for the pull request. I just replied on github. In brief, I would prefer to keep the transceiver as simple as possible to provide an easy to use base that can be easily adapted to ones needs. I think there are many aspects/paramters that can be studied, but I’m afraid it would make the code much more complicated if we introduce options for all of them. (Replacing the MM Clock Recovery with something more robust would, of course, still be a good idea in my opinion.) Best, Bastian
-- Dipl.-Inform. Bastian Bloessl Distributed Embedded Systems Group University of Paderborn, Germany |
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