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.
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