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Re: [Discuss-gnuradio] Very low packet loss rate for the discontinuous B

From: Alex Zhang
Subject: Re: [Discuss-gnuradio] Very low packet loss rate for the discontinuous BPSK communications- the analysis and looking for solution
Date: Thu, 7 Mar 2013 00:16:00 -0600

Besides the tips mentioned in the previous mails, I am wondering if the carrier recovery can performed by adding proper preamble fore the burst mode bpsk communication. 
Several books mentioned that but did not provide more details;

for example:

Radio System Design for Telecommunication 

 By Roger L. Freeman
page 417.

Satellite Communication
 By Dharma Raj Cheruku
page 138

Especially the latter book, a preamble with 352 bits are used as carrier recovery, which is much faster than the my current FLL.
I am wondering if any guy who have similar implementation.

On Wed, Mar 6, 2013 at 7:08 AM, Tom Rondeau <address@hidden> wrote:
On Wed, Mar 6, 2013 at 6:42 AM, Sreeraj Rajendran
<address@hidden> wrote:
>>>I don't believe this problem can be solved by adjusting the loop
>>> bandwidth.
> Acquisition time is roughly inversely proportional to loop_bw and error
> variance is proportional to loop_bw. So there is always a tradeoff between
> acquisition time and tracking performance. You should try adjusting loop_bw
> (http://www.trondeau.com/blog/2011/8/13/control-loop-gain-values.html).
>>>Applying faster tracking algorithm may solve this problem, but I think it
>>> takes long time to develop for a new guy.
> If you have a good understanding of the algorithm, its really easy to
> prototype the alogorithm in GRC or  by using gnuradio python-block coding
> support. "gr_modtool" is always there to make block coding easier.
> -Sreeraj

Also hand tune to make sure the frequencies of the transmitter and
receiver are as close as you can get them. The slowest loop in this
chain is the frequency lock loop, so overcome that by hand and see
what happens.


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