On Fri, Aug 23, 2013 at 01:50:14PM +0200, Bastian Bloessl wrote: > >Only we're not filtering--we're adding a tapering window in time domain. > >At the beginning of the symbol, we can simply multiply the samples with > >the up-ramp of our tapering window (we use a raised cosine flank). > > > >So what happens at the end? We could do the same: Multiply the last few > >samples with the down-ramp. But then we're simply throwing away energy. > >It would be much nicer if the down-ramp came *after* the symbol, during > >the up-ramp of the following symbol. This is achieved by adding samples > >from the beginning of the symbol (think of it as a "cyclic postfix") and > >multiply those with the down-ramp of the tapering window. > > Ah OK, I see, taking the samples from the end is indeed stupid -.- > Thanks for your explanation!
Hi Bastian, just a quick follow-up: Did you have any problems with the rolloff spectrum, or what caused you to change the code? I checked the output, and it seemed correct--although I didn't have the theoretical values here to compare the results to those. MB -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-43790 Fax: +49 721 608-46071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association
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