Re: [Discuss-gnuradio] Changing interp rate dynamically?

[Eric Blossom]

On Fri, Sep 14, 2007 at 01:16:58PM -0400, Michael Dickens wrote:
> I've created an "analog repeater" that's just:
> 
> usrp source -> amp -> usrp sink
> 
> and I'd like to control the "bandwidth" that's repeated  
> dynamically ... on the fly via a GUI slider.  I have created all of  
> this, and on init everything works just fine.  But the moment I  
> change the bandwidth value to -anything-, including the original  
> values, the TX stops.
> 
> I'm also displaying the output of the 'amp' on a waterfall scope, so  
> I can see that the USRP source is generating data all of this time.   
> It seems like the decim rate of the source is being changed properly.
> 
> I've tracked this down through Python and C++, and everything looks  
> OK .. nothing else is touched in the process of setting the sink's  
> interp rate.  In usrp_standard_tx::set_interp_rate, an FPGA register  
> is changed to reflect the new interp rate; I haven't tried tracking  
> down that side of things, since I've never investigated FPGA code and  
> really don't have time to right now.
> 
> Hence the question for folks who hopefully know better: Can the  
> interp rate be changed dynamically ... after its original init?  I  
> should think this would be OK, but obviously it's not working for  
> me.  Thanks in advance! - MLD

Hmmm, I would expect it to work.  
Changing the decimation on the fly definitely works.
Can't say that I've tried changing the interpolation on the fly.

Eric