FLL Band-Edge Detectors: Literature?


#1

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


#2

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.invalidwrote:

Karlsruhe Institute of Technology (KIT)
Fax: +49 721 608-46071


Muhammad Nazmul I.

Graduate Student
Electrical & Computer Engineering
Wireless Information & Networking Laboratory
Rutgers, USA.


#3

On Mon, Oct 1, 2012 at 12:00 PM, Nazmul I.
removed_email_address@domain.invalid wrote:

On Mon, Oct 1, 2012 at 11:40 AM, Martin B. (CEL) 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 :slight_smile:

Tom


#4

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 :slight_smile:

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


#5

On Tue, Oct 2, 2012 at 9:01 AM, Martin B. (CEL)
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


#6

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