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 Kaiserstraße 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-Württemberg and National Laboratory of the Helmholtz Association
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