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Re: [Discuss-gnuradio] time to reconfigure a block in flowgraph


From: Steve Mcmahon
Subject: Re: [Discuss-gnuradio] time to reconfigure a block in flowgraph
Date: Fri, 17 Dec 2010 10:28:01 -0800 (PST)

Hello Martin Braun:

I'm not sure what you mean. There is no set_center_freq() method in 
gr_sig_source_c.

When you say the best way to implement frequency hopping is to "use a larger 
bandwidth and do the tuning digitally", you mean to do the tuning in software 
in the Python flowgraph using Gnuradio blocks?

Thanks.

Steve McMahon


--- On Fri, 12/17/10, Martin Braun <address@hidden> wrote:

> From: Martin Braun <address@hidden>
> Subject: Re: [Discuss-gnuradio] time to reconfigure a block in flowgraph
> To: address@hidden
> Date: Friday, December 17, 2010, 3:36 AM
> On Thu, Dec 16, 2010 at 05:32:23PM
> -0800, Steve Mcmahon wrote:
> > Hello:
> > 
> > I need some help on a timing issue.
> > 
> > I have a timer running on a separate thread which
> changes parameters in my flow graph every 100ms or 200ms.
> When I change the frequency of my Signal Source by using
> gr.sig_source_c.set_frequency(), the timer thread is still
> able to fire every 100ms or 200ms and change the tone
> frequency every cycle. However, when I try to also change
> the center frequency in the timer thread with
> usrp2.sink_32fc.set_center_freq(), it cannot keep up and
> often takes more than 100ms or 200ms.
> > 
> > How long do functions such as
> usrp2.sink_32fc.set_center_freq() take to execute? Do I need
> to to gr.lock() and gr.unlock() my flowgraph before changing
> these kind of parameters? How can I change parameters every
> 100ms?
> 
> Not the most general answer you can get, but if you want to
> do *precise*
> retuning (e.g. for frequency hopping) to my best knowledge
> the way to go
> is to use a larger bandwidth and do the tuning digitally.
> You don't have
> to use lock() for retuning the usrp (just as you don't have
> to do so for
> calling set_center_freq() on the sig_source).
> 
> Cheers,
> MB
> 
> -- 
> Karlsruhe Institute of Technology (KIT)
> Communications Engineering Lab (CEL)
> 
> Dipl.-Ing. Martin Braun
> Research Associate
> 
> Kaiserstra├če 12
> Building 05.01
> 76131 Karlsruhe
> 
> Phone: +49 721 608-3790
> Fax: +49 721 608-6071
> www.cel.kit.edu
> 
> KIT -- University of the State of Baden-W├╝rttemberg and
> National Laboratory of the Helmholtz Association
> 
> 
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