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From: | Nowlan, Sean |
Subject: | Re: [Discuss-gnuradio] Correlation Estimator Over the Air |
Date: | Wed, 14 Oct 2015 14:43:57 +0000 |
We saw a lot of improvement in the performance of the Correlation Estimator block once we calculated a level for the AGC. In our case, we're looking for a BPSK preamble that is a pseudorandom sequence. The corr_est block is provided with the match-filtered
version of the preamble sequence. So we calculated the average energy per sample of that sequence as K = \frac{ \sum_{i}^{N}(\abs{seq}^2) }{ N }. (Sorry if the LaTeX notation is a bit off). So K is the target level we use in the AGC2 block. This seems to work
pretty well for us.
Sean
From: discuss-gnuradio-bounces+address@hidden <discuss-gnuradio-bounces+address@hidden> on behalf of Washbourne,
Logan <address@hidden>
Sent: Tuesday, October 13, 2015 12:03 PM To: GNURadio Discussion List Subject: Re: [Discuss-gnuradio] Correlation Estimator Over the Air Rich,
Ah, that makes so much sense now. I was modulating all that came out of the costas loop and packing the bits into bytes which essentially means I was undoing the syncing the blocks before it were doing. This morning I tried searching for the preamble in
the binary stream that was output from the constellation decoder and I found it. It was 98 samples in, which confused me, but now that I know I am looking for a tag then that makes perfect sense.
I just tried that same process, looking for the preamble in the binary stream(using matlab) for the over the air program and I still can't find it, but I am going to play around with the AGC block and see if I can't tweak it enough to work.
I really appreciate your help, I finally feel like I'm getting close to my goal.
Logan Washbourne
Electrical Engineering Graduate StudentOn Tue, Oct 13, 2015 at 10:55 AM, Richard Bell
<address@hidden> wrote:
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