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Re: [Discuss-gnuradio] strange receiver behaviour with UHD

From: Per Zetterberg
Subject: Re: [Discuss-gnuradio] strange receiver behaviour with UHD
Date: Tue, 28 Sep 2010 15:53:00 +0200

On Tue, 2010-09-28 at 15:15 +0200, Patrik Eliardsson wrote:
> Dear List,
> We have made a test program using a source and a file sink (see fg.jpg) where 
> we are receiving a fixed number of samples (with UHD and USRP2 and WBX-card) 
> from an AWGN-generator (constant power -19dB).  If we plot the abs value of 
> the received signal we always see a "spike" in the 10 first samples (see 
> fig1) before the abs value settles to a more expected value. Sometimes 
> (seldom) there is no "spike" but the result is still not as expected, the 
> received data starts at a higher level and slopes down during a quite long 
> time before settling to a stable level (see fig 2).
> Have we missed something or why does this "spike" occur? Is there some 
> initialization time in the hardware that we need to take into consideration 
> before we start to receive samples (recv) after setting all parameters?
> Br,
> Patrik 
> _______________________________________________ Discuss-gnuradio mailing list 
> address@hidden http://lists.gnu.org/mailman/listinfo/discuss-gnuradio

I see also some kind of transient spur the 1000-2000 first samples when
using XCVR2450 (I have mentioned this before on the list :-). Next time
I have a basic dB connected I will check if this behavior is observed
also there. I always discard the 1000-2000 samples to avoid the problem.


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