set
Phase plot is showing some sinusoidal output. Attached are the two phase
Sam,
algorithm is trying to track. Also noise will affect if somewhat as it
tries to keep a lock. The fact that it looks like it’s actually
oscillating is interesting. Have you tried to reduce the loop
bandwidth to see how that affects things?
Tom
Thanks Tom,
Currently, I am tracking a simulated signal (although I am getting zero
BER
through USRPs as well). There is currently no additive noise. Reducing
loop
bandwidth by a factor of 4 gives nice plots, as tracking become good by
reducing noise bandwidth. But, steady state value of 24 reaches after
approximately 9000samlples. That means my loop is taking 9000/4 symbols
to
get lock? And after that it 'll produce desired output. Am i doing
something wrong? Something I am missing?
Attached are the snapshots of new phase plots.
–
Best Regards,
Sam
On Mon, Apr 15, 2013 at 12:25 AM, Sam mite [email protected]
wrote:
varying different parameters I want to observe the lock time/symbols
max rate dev = 1.5
You’re going to see some movement, plus or minus, around the closest
Thanks Tom,
–
Best Regards,
Sam
Sam,
No, I don’t think that you are doing something wrong here. But those
figures you’ve posted look like the circuit is under-damped. It should
be critically damped, so it’d be interesting to see what’s going wrong
inside of the algorithm. I’ve looked at it with this in mind, but I
can’t see that anything is being done differently than the normal
control loops that we use, and the parameters should be set to be
critically damped.
This sounds like something we can develop and discuss on the signal
processing wiki page. Would you be able to start something here?
There’s already a section for Synchronization. Maybe just create a new
page off that for discussing this particular algorithm/block.
(for signing up to post on the wiki:
http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#How-can-I-post-on-this-wiki-use-the-bug-tracker)
Thanks!
Tom