[Discuss-gnuradio] Re: analysis_filterbank question

[Markus Feldmann]

feldmaus schrieb:
> First i post a clipping from the api docu about the analysis filterbank:
> 00043     def __init__(self, mpoints, taps=None):
> 00044         """
> 00045         Takes M complex streams in, produces single complex stream out
> 00046         that runs at M times the input sample rate
> 00047 
> 00048         @param mpoints: number of freq bins/interpolation factor/subbands
> 00049         @param taps:    filter taps for subband filter
> 00050 
> 00051         The channel spacing is equal to the input sample rate.
> 00052         The total bandwidth and output sample rate are equal the input
> 00053         sample rate * nchannels.
> 00054 
> 00055         Output stream to frequency mapping:
> 00056         
> 00057           channel zero is at zero frequency.
> 00058 
> 00059           if mpoints is odd:
> 00060             
> 00061             Channels with increasing positive frequencies come from
> 00062             channels 1 through (N-1)/2.
> 00063 
> 00064             Channel (N+1)/2 is the maximum negative frequency, and
> 00065             frequency increases through N-1 which is one channel lower
> 00066             than the zero frequency.
I am now working on a Report, it would be nice if some of the developers
explain what they mean with <channels 1 through (N-1)/2> ?
What means <Channel (N+1)/2 is the maximum negative frequency> ?

Does this formula above also valid with a bandpass_filter ?

Or how should the algorithmus be for a bandpass ?

Regards markus