Re: [Discuss-gnuradio] Troubled by the pfb channelizer center frequency location

[LD Zhang]

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 5^th one on the list)! Whoo! It would be nice to tell a newcomer about this.

 

LD

 

From: LD Zhang [mailto:address@hidden
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