Re: [Patch-gnuradio] gr_rotator fix/optimization

[Robert McGwier]

In DttSP,  the correction is done every dsp blocksize which is O(1024) 
where the constant is a small number < 5.

We have measured in a laboratory that the carrier phase noise < -125 dBc 
at 1 kHz.  We could not do better than this in the Flex 5000 system 
because there were other things that limited the phase noise to this level.

Bob



Matt Ettus wrote:
> Dan Halperin wrote:
> > I ran some quick trials and found that C takes around 18k (I was
> > surprised it was this fast, actually!) iterations for the phaser
> > amplitude to be off by 0.1%. So K around a hundred or a thousand should
> > be good.
>
> 0.1% is -60dBc.  After 100K interations, it will be 0.55%  ( 0.999 ^
> (100K/18K) ), which is only 45dB down.  On the other hand, if we do the
> correction every 1000 points, the error will be -85 dBc   ( 0.999 ^
> (1K/18K) ).
>
> Thanks for investigating this!
>
> Matt
>
>
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