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Re: [Discuss-gnuradio] continuous data collection?
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] continuous data collection? |
Date: |
Sun, 26 Feb 2006 17:00:40 -0800 |
User-agent: |
Mutt/1.5.9i |
On Sun, Feb 26, 2006 at 11:23:08AM -0500, Clark Pope wrote:
> I've been collecting snapshots through my DBS and USRP to do DBPSK and
> DQPSK bit error rate testing. I'm not able to get the BER below about 1e-5.
> It seems that slips are occuring spontaneously in the data even though no
> over/underflow is reported during the collection.
What are you using as your input signal? How's the level/gain? What
is the avg peak signal level you are seeing from the USRP? What
decimation rate are you using? Are you running some kind of symbol
tracking algorithm?
> Questions:
> 1. Has anyone successfully done long term collections without any slips?
Yes. I've run the gsmk2 code at 500k bit/sec with no FEC and no
errors for many (10's ?) seconds at a time.
> 2. Are the O/U flags sticky?, i.e. if I don't see an under or overflow
> reported then I can be sure the fifos were okay?
You're building from CVS, right? There was a xrun reporting
problem that was fixed a couple of months ago.
Yes, they are sticky. They are checked and cleared at about 10 Hz.
> I've done BERs from 1 Mbaud to 11 Mbaud all with the same frequency of
> slips so it does not appear to be speed related.
Eric