Thank you Martin. Knowing that there is no fundamental reason that this setup would not work, led me to investigate a different section of my code & I discovered that I was running with a usrp decimation too low for my system & a wav file with too high a sample rate.
As for the short int wav file, I'm writing this code so that a number of students, who don't use anything but matlab, will have access to the usrp board for their various experiments. I can cut out the FIR filter if I desire & require a compatible input wav file sampling rate... I was just trying to make it flexible to input wav files of varying sample rates. I have a competing desire to make it efficient, as I my be running this on a 333 mHz PC-104 board. So, its a tradeoff. That said, it works beautifully now. Thanks again. Justin On Fri, May 15, 2009 at 3:56 AM, Martin Braun <[email protected]>wrote: > On Wed, May 13, 2009 at 04:25:39PM -0400, Justin G. Eskesen wrote: > > P.S. I've tried both wavfile_source & file_source & neither work. I'm > aware of > > the -1.0 to 1.0 normalization in wavfile_* & have commented that portion > of the > > code out. If I get this to work, I'll write a wavfile_source & sink that > do no > > rescaling & take shorts because I'm doing too many unecessary > conversions. > > For the start, it probably would have been better to put in a > gr.multiply_const_ff() after the filter with a value of something like > 20000. In the setup you mentioned, reading shorts from the WAV file > would not have helped, since you're using a float FIR afterwards, and a > short FIR would introduce too much quantization noise. > > I've tried pretty much exactly the same setup before (but with the > multiplier) and it worked. Also, for debugging, I recommend using a > file_sink (not a wavfile_sink) instead of the USRP and check the sample > values in that file scale well in the DAC range. Actually, if you /did/ > pipe it to WAV or audio, it should /not/ work, since they rely on data > being between -1 and 1. > > Should you do ever do write a short wavfile_* and also want to support 8 > Bit, remember that scales differently. > > Hope this was what you wanted. > MB > > > -- > Dipl.-Ing. Martin Braun Phone: +49-(0)721-608 3790 > Institut fuer Nachrichtentechnik Fax: +49-(0)721-608 6071 > Universitaet Karlsruhe (TH) http://www.int.uni-karlsruhe.de/ > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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