On Fri, Nov 22, 2013 at 7:14 PM, Paul B. Huter <paul.b.hu...@gmail.com> wrote: > I am trying to view the spectrum from 0-1MHz recorded at 50M. I used a low > pass filter to only record 0-30MHz. My frequency translating filter is > defined as follows: > > Decimation: 50 > Taps: firdes.low_pass(1, samp_rate, 500000, 100) > Center Frequency: -500000 > Sample Rate: samp_rate > > samp_rate: 50M > > Any ideas? > > Paul B. Huter
Let's take a look at what the frequency_xlating filter does: http://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1freq__xlating__fir__filter__ccc.html It filters a signal at the center frequency you set and then moves that signal to baseband. You've set a sampling rate of 50 Msps and a center frequency of -50 kHz. Which means you want to get the signal at -50 kHz moved to baseband. The output signal will be from -500 kHz to +500 kHz. You should basically be seeing what you would if you set the center frequency to 0 since you're only moving 50 kHz out of 1 MHz of spectrum. What's the exact problem you're facing, then? (Also, once again, you're setting a very tight transition band here that would cause a gigantic filter.) Tom _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
