Hi Martin, Thanks for the answer and my apologies for the guessing work.
I reviewed my test code and it turns out that, as you say and as I was expecting, gr_delay works fine. A custom block I built is the one to blame for the misbehavior I'm seeing. I'll work on my custom block and eventually post another question in case I can't figure out by myself the problem. Thanks, Carlos. On Mon, Feb 22, 2010 at 1:51 PM, Martin Braun <[email protected]> wrote: > On Mon, Feb 22, 2010 at 10:42:08AM +0100, Carlos Aviles wrote: >> gr_delay is intended to delay the input of the signal by n samples. >> I've been doing some testing with that block and I have observed that >> the delay is applied to the chunk of data that the block receives as >> input (on my case that was some 8000 samples) and applied again to the >> next chunk. >> >> I see two problems with that. >> >> - I'm not able to apply the delay once (to the very beginning of the >> signal). This is actually a very trivial problem that could be solved >> building a custom block. >> - If the delay I want to apply is larger than the size of the data >> that the block receives (say a delay of 10000 samples when the block >> receives the data in chunks of 8000 samples), the signal is set to 0 >> as if applying an infinite delay. > > If you'd have pasted some code, the diagnosis would have been a bit > simpler, but I'll give it a try: > > gr_delay works as you explained. If you set delay to N, the first N-1 > outputs will be zero, after that, everything will work as expected. > Of course, you must send at least N items before you get anything at > the output. > > Concerning your second point: what do you mean by chunk size? Are you > talking about what GNU Radio passes between blocks? If so, ignore that, > GNU Radio will do the right thing. Or have you set itemsize to 8000 * > gr.sizeof_gr_float? In that case, remember you have to pass 800000000 > samples (in blocks of 8000 samples each) through gr_delay before you've > reached a delay of 10000. > > Please post your questions such that the answer requires less guesswork. > > 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 > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
