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Re: [Discuss-gnuradio] FLL Band-Edge Detectors: Literature?
From: |
Martin Braun (CEL) |
Subject: |
Re: [Discuss-gnuradio] FLL Band-Edge Detectors: Literature? |
Date: |
Tue, 2 Oct 2012 15:01:14 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Oct 01, 2012 at 05:17:33PM -0400, Tom Rondeau wrote:
> Yes, harris' book is the best to start with. There is another paper
> from him called "Let's Assume the System is Synchronized" that also
> goes over it. I'm not sure if he's published a paper that discusses
> the specifics of the filter derivation, yet, though. It's based on the
> derivative of the half cosine waveform of the RRC filter rolloff. The
> system behaves much better this way than just generating any random
> band edge filter.
>
> In theory, this should work for any signal using an RRC pulse shaping.
> For specific constellations, you could use a Costas loop with a wider
> lock in bandwidth to handle the frequency offset.
>
> Oh, and I might be the only one who calls this the "FLL band edge
> filter" specifically to point out that this is only one possible
> implementation of an FLL for coarse frequency tracking. Other
> algorithms are welcome :)
Thanks for these pointers. For future reference (and the mailing list
archives):
* The paper "Let's Assume the System is Synchronized" is a good
introduction and provides a great and simple explanation.
* Harris' book "Multirate Signal Processing: for communication systems"
is the more complete version, down to polyphase implementation
details.
* I should have realized this is a way to implement an ML Frequency
correction for RRC spectra without a-priori knowledge. This is more
generally derived in "Synchronization techniques for digital
receivers" by Mengali/D'Andrea[1], and probably many other places.
M
[1] In general, Fred Harris books and papers are more fun to read,
though.
--
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)
Dipl.-Ing. Martin Braun
Research Associate
Kaiserstraße 12
Building 05.01
76131 Karlsruhe
Phone: +49 721 608-43790
Fax: +49 721 608-46071
www.cel.kit.edu
KIT -- University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association
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