You are probably using an odd interpolation ratio. You need to use an even rate in order to get a flat passband.
The WBX does not have adjustable filtering. Matt On Wed, Feb 13, 2013 at 10:42 PM, Ralph A. Schmid, dk5ras <ra...@schmid.xxx>wrote: > Hi, > > I use an USRP1 together with gnuradio/GRC and would like to transmit an > OFDM > signal, abt. 1 MHz bandwidth at 433 MHz. The FFT display block within GRC > shows the power mask as expected, a flat line over the bandwidth, and steep > drops at both ends. What a real spectrum analyzer at the output shows is > something totally different, like a Gaussian distribution of the emitted > energy, with highest amplitude in the center, bandwidth as configured, but > the amplitude is dropping continuously towards the ends for about 70 dB or > so. Adjusting the channel bandwidth in the sink block has no influence, > maybe the WBX anyway does not support adjustable filtering?! > > Even the simplest possible setup, like random source, OFDM modulator and > URSP, shows this behavior. > > What am I doing wrong? > > Btw., the spectrum analyzer is a professional device and out of any doubt > :) > LTE, DAB and DVB-T is shown as expected. > > Ralph. > > > -- > > Ralph A. Schmid > Mondstr. 10 > 90762 Fürth > +49-171-3631223 > ra...@schmid.xxx > http://www.bclog.de/ > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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