AGC loop and digital mods

Eric,

Here’s a brief write-up on the tests I ran for the AGC loops. It looks
like
the feedforward has a slight advantage over most of the test cases.

I thought I’d email this to the listserv in case anyone is interested in
the
digital modulations. Basically, we’re working on getting stable DBPSK
and
DQPSK modulators into the code base. The AGC loops seems to be producing
problems, much of which is caused by driving the Costas loop crazy at
the
next stage of the receiver. Future work will include creating a
non-coherent
receiver for the differential modulations to take out the Costas loop.

Tom

On Mon, Sep 25, 2006 at 11:35:33PM -0400, Tom R. wrote:

receiver for the differential modulations to take out the Costas loop.

Tom

Hi Tom, thanks for making the measurements and writing them up.

I’ll be merging the results of all this work into the trunk tomorrow.
Thanks to Tom for all the effort he’s put into sorting out the DBPSK
and DQPSK. And thanks to Matt for suggesting the feed forward AGC.

Eric

The feedforward AGC system in DttSP is more complex in that it is two
track (fast and “user set”). I believe I already mentioned this so I
won’t go over it again. But let me reiterate one important feature of
our work. One of the things that was important to its success as a
feedforward agc was to respond to a level change 3 times constants early
in a simple predictive system. The 3 time constants varied depending
on the changing speed of the agc as set by the user.

Bob

‘Eric B.’ wrote:

DQPSK modulators into the code base. The AGC loops seems to be producing
I’ll be merging the results of all this work into the trunk tomorrow.
Thanks to Tom for all the effort he’s put into sorting out the DBPSK
and DQPSK. And thanks to Matt for suggesting the feed forward AGC.

Eric


Robert W. McGwier, Ph.D.
Center for Communications Research
805 Bunn Drive
Princeton, NJ 08540
(609)-924-4600
(sig required by employer)

On Wed, Sep 27, 2006 at 01:44:34PM -0400, Robert W McGwier wrote:

The feedforward AGC system in DttSP is more complex in that it is two
track (fast and “user set”). I believe I already mentioned this so I
won’t go over it again. But let me reiterate one important feature of
our work. One of the things that was important to its success as a
feedforward agc was to respond to a level change 3 times constants early
in a simple predictive system. The 3 time constants varied depending
on the changing speed of the agc as set by the user.

Bob

Thanks!

BTW, what’s the link to the current/svn/cvs DttSP code?

Eric

svn co svn://206.216.146.154/svn/repos_sdr_dttsp/trunk dttsp

‘Eric B.’ wrote:

Bob
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