# FLL Band-Edge Detectors: Literature? **URL:** \ **Category:** GNU Radio\ **Created:** [October 1, 2012, 5:41pm UTC](https://www.ruby-forum.com/t/fll-band-edge-detectors-literature/223356 "2012-10-01T17:41:38Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![aris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/258eb7/32.png) [@aris](https://www.ruby-forum.com/u/aris)\ **Post date:** [October 1, 2012, 5:41pm UTC](https://www.ruby-forum.com/t/fll-band-edge-detectors-literature/223356/1 "2012-10-01T17:41:38Z")
Hi, is there any literature that goes with the FLL synch blocks in gr-digital? Ironically, Google always points me to the GR source files when I search for ‘fll band edge’ related topics. M – Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin B. 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 ---
**Author:** ![Martin\_BSSCEL](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/73ab20/32.png) [@Martin\_BSSCEL](https://www.ruby-forum.com/u/Martin_BSSCEL)\ **Post date:** [October 1, 2012, 6:02pm UTC](https://www.ruby-forum.com/t/fll-band-edge-detectors-literature/223356/2 "2012-10-01T18:02:06Z")
Hello, Frederic Harris’s “Multirate Signal Processing: for communication systems” has a section on FLL band edge sync. I think that the GR-digital code was designed based on these algorithms. Tom or other GNUradio block designers can verify it. Thanks, Nazmul On Mon, Oct 1, 2012 at 11:40 AM, Martin B. (CEL) [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote: > Karlsruhe Institute of Technology (KIT) > Fax: +49 721 608-46071 – Muhammad Nazmul I. Graduate Student Electrical & Computer Engineering Wireless Information & Networking Laboratory Rutgers, USA. ---
**Author:** ![Martin\_BSSCEL](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/73ab20/32.png) [@Martin\_BSSCEL](https://www.ruby-forum.com/u/Martin_BSSCEL)\ **Post date:** [October 1, 2012, 11:18pm UTC](https://www.ruby-forum.com/t/fll-band-edge-detectors-literature/223356/3 "2012-10-01T23:18:55Z")
On Mon, Oct 1, 2012 at 12:00 PM, Nazmul I. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > On Mon, Oct 1, 2012 at 11:40 AM, Martin B. (CEL) [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > wrote: > > > Hi, > > > > is there any literature that goes with the FLL synch blocks in > > gr-digital? Ironically, Google always points me to the GR source files > > when I search for ‘fll band edge’ related topics. > > > > M Martin, 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 🙂 Tom ---
**Author:** ![Martin\_BSSCEL](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/73ab20/32.png) [@Martin\_BSSCEL](https://www.ruby-forum.com/u/Martin_BSSCEL)\ **Post date:** [October 2, 2012, 3:02pm UTC](https://www.ruby-forum.com/t/fll-band-edge-detectors-literature/223356/4 "2012-10-02T15:02:12Z")
On Mon, Oct 01, 2012 at 05:17:33PM -0400, Tom R. wrote: > 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 B. 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 ---
**Author:** ![Martin\_BSSCEL](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/73ab20/32.png) [@Martin\_BSSCEL](https://www.ruby-forum.com/u/Martin_BSSCEL)\ **Post date:** [October 2, 2012, 3:40pm UTC](https://www.ruby-forum.com/t/fll-band-edge-detectors-literature/223356/5 "2012-10-02T15:40:47Z")
On Tue, Oct 2, 2012 at 9:01 AM, Martin B. (CEL) [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > For specific constellations, you could use a Costas loop with a wider > > - The paper “Let’s Assume the System is Synchronized” is a good > > [1] In general, Fred Harris books and papers are more fun to read, > though. Yeah, Mengali’s great, but dense and mathematical. harris provides a more big-picture, system’s oriented look at the problems. Tom ---
**Author:** ![aftab](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c57346/32.png) [@aftab](https://www.ruby-forum.com/u/aftab)\ **Post date:** [March 17, 2019, 4:15pm UTC](https://www.ruby-forum.com/t/fll-band-edge-detectors-literature/223356/6 "2019-03-17T16:15:59Z")
Hi, I recently got a chance to read Wireless Communications from the Ground Up - An SDR Perspective by Qasim Chaudhari which contains a detailed description on band edge filters for FLL and timing purposes. The way he explains things makes it really easy to grasp the whole idea of any topic. PhD Student Aftab Ahmad Communications, Signal Processing, and Networking Center at Istanbul Medipol University School of Engineering and Natural Sciences Istanbul Medipol University Kavacik Mah., Ekinciler Cad., No:19, Beykoz, 34810, Istanbul