DPSK demod parameters question

GNU Radio
1

HI list!

I am working with DPSK mod and demod blocks. I would like to know if
anyone
knows what is the meaning of the parameters in DPSK demod. I’ve looked
for
them but I havent found anything.

The parameters are:
FLL Bandwidth
Phase Loop Bandwith
Timing bandwith
Omega relative limit

What do these parameters refer to?? Thanks in advance.

Att
Javier M.

2

On Wed, Jul 11, 2012 at 10:07:09AM +0200, Martin B. (CEL) wrote:

What is confusing is the ‘omega’ parameter, I must admit, because it’s
not actually connected (it doesn’t do anything). Now if you think about
a PSK Rx for a second, you /might/ expect an AGC, and I’m guessing
that’s where that parameter went. But as I said, ignore that.

Ahh, the shame. Omega was part of the clock recovery, not the AGC.

But in the GRC block, it still doesn’t do anything.

MB

–
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

3

On Tue, Jul 10, 2012 at 11:40:00AM -0500, Javier M. Suarez wrote:

I am working with DPSK mod and demod blocks. I would like to know if anyone
knows what is the meaning of the parameters in DPSK demod. I’ve looked for them
but I havent found anything.

Hi Javier,

assuming you know how a PSK receiver works:

The parameters are:
FLL Bandwidth
Phase Loop Bandwith
Timing bandwith
Omega relative limit

This block does everything from complex samples to bits.
The 3 bandwidths set the parameters for frequency, clock and phase
recovery (Tom explained the bw parameter quite well here:
http://gnuradio.squarespace.com/blog/2011/8/13/control-loop-gain-values.html)

What is confusing is the ‘omega’ parameter, I must admit, because it’s
not actually connected (it doesn’t do anything). Now if you think about
a PSK Rx for a second, you /might/ expect an AGC, and I’m guessing
that’s where that parameter went. But as I said, ignore that.

About finding that stuff: the FLL is actually documented quite well
(check e.g.
http://gnuradio.org/doc/doxygen/classdigital__fll__band__edge__cc.html,
which is the 3rd result for a ‘gnuradio fll’ google search on my end),
but it’s not filed under ‘synchronization’, so perhaps that’s where you
went wrong.

MB

–
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