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