[Discuss-gnuradio] Troubled by the pfb channelizer center frequency location
Dear Group, I am learning to do the pfb channelizer using the now famous example on the documentation page at: http://gnuradio.org/doc/doxygen/page_pfb.html The example is at the end of the page, where a 9-subchannels are pulled out of the original 9 kHz bandwidth signal. The original signals' tones are at [freqs = [-4070, -3050, -2030, -1010, 10, 1020, 2040, 3060, 4080] The original signal bandwidth should be from -4500 to 4500 Hz. According to my understanding the first channel signal should be centered at -70 Hz, since the 9 channels' centers should be at [-4000, -3000, ..., 3000, 4000]. But the output plot from the example shows that the first tone is at slightly greater than 0 Hz frequency. I don't know what is going on here? LD ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Troubled by the pfb channelizer center frequency location
I guess I got it! The default channel map is such that the first channel is the UN-fftshifted frequency location which is at 10 Hz (the 5th one on the list)! Whoo! It would be nice to tell a newcomer about this. LD From: LD Zhang [mailto:ldz10...@gmail.com] Sent: Wednesday, May 15, 2013 4:16 PM To: discuss-gnuradio Discussion Group Subject: Troubled by the pfb channelizer center frequency location Dear Group, I am learning to do the pfb channelizer using the now famous example on the documentation page at: http://gnuradio.org/doc/doxygen/page_pfb.html The example is at the end of the page, where a 9-subchannels are pulled out of the original 9 kHz bandwidth signal. The original signals' tones are at [freqs = [-4070, -3050, -2030, -1010, 10, 1020, 2040, 3060, 4080] The original signal bandwidth should be from -4500 to 4500 Hz. According to my understanding the first channel signal should be centered at -70 Hz, since the 9 channels' centers should be at [-4000, -3000, ..., 3000, 4000]. But the output plot from the example shows that the first tone is at slightly greater than 0 Hz frequency. I don't know what is going on here? LD ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Troubled by the pfb channelizer center frequency location
On Thu, May 16, 2013 at 12:26 AM, LD Zhang wrote: > I guess I got it! The default channel map is such that the first channel is > the UN-fftshifted frequency location which is at 10 Hz (the 5th one on the > list)! Whoo! It would be nice to tell a newcomer about this. > > LD > Glad you got it working. You could have read the documentation on the block, though: http://gnuradio.org/doc/doxygen/classgr_1_1filter_1_1pfb__channelizer__ccf.html Look at the 'set_channel_map' function. It explains the channel mapping; and how to change it. Tom > > From: LD Zhang [mailto:ldz10...@gmail.com] > Sent: Wednesday, May 15, 2013 4:16 PM > To: discuss-gnuradio Discussion Group > Subject: Troubled by the pfb channelizer center frequency location > > > > Dear Group, > > I am learning to do the pfb channelizer using the now famous example on the > documentation page at: > > http://gnuradio.org/doc/doxygen/page_pfb.html > > The example is at the end of the page, where a 9-subchannels are pulled out > of the original 9 kHz bandwidth signal. The original signals' tones are at > > [freqs = [-4070, -3050, -2030, -1010, 10, 1020, 2040, 3060, 4080] > > The original signal bandwidth should be from -4500 to 4500 Hz. > > > > According to my understanding the first channel signal should be centered at > -70 Hz, since the 9 channels' centers should be at [-4000, -3000, ..., 3000, > 4000]. > > But the output plot from the example shows that the first tone is at > slightly greater than 0 Hz frequency. > > I don't know what is going on here? > > LD > > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
