So, does this mean that when I give a PFB size of 16384 and taps of 2, the module actually takes in 32768 samples, multiplies the window function, rearranges them as 2 16384 samples, adds them and sends it to the FFT as a single input stream, where the FFT happens for this number of samples? Right ?
Also, in the biplex fft block (not 2x or 4x), just the biplex fft, I'm able to set the "number of inputs" as 1 (ie 2^0) but still the block shows me two inputs in0 and in1. Can I simply connect a constant 0 block to the input I don't want to use ? Is there a more elegant way of doing a fft for a single input stream with only one input ? Thanks ! On Mon, Dec 14, 2015 at 9:08 PM, Rachel Domagalski <[email protected]> wrote: > The variable PFBsize is the same as your FFT size. The number of taps > determines the number of filter coefficients in the PFB, which is > TotalTaps*2^PFBsize. See the wiki page for reference: > https://casper.berkeley.edu/wiki/The_Polyphase_Filter_Bank_Technique#The_Math_Behind_the_PFB > > On Mon, Dec 14, 2015 at 6:16 AM, Mugundhan vijayaraghavan < > [email protected]> wrote: > >> Hello again, >> >> One other question: >> Is there a relation between the taps of the PFB FIR and the number of >> input streams to the FFT_Biplex module ? >> >> Size of PFB: (2?)PFBSizeThe number of channels in the PFB (this should >> also be the size of the FFT which follows).Total Number of Taps:TotalTapsThe >> number of taps in the PFB FIR filter. Each tap uses 2 real multiplier cores >> and requires buffering the real and imaginary streams for 2*P**F**B**S* >> *i**z**e* samples.Windowing FunctionWindowTypeWhich windowing function >> to use (this allows trading passband ripple for steepness of rolloff, >> etc).Number >> of Simultaneous Inputs: (2?)n_inputsThe number of parallel time samples >> which are presented to the FFT core each clock. The number of output ports >> are set to this same value. >> >> From the above tab in the blockumentation I see that *number of >> simultaneous inputs* is the parallel time samples presented to the fft >> core. >> >> Does this mean say, I have a 16384 PFB size, setting the taps as two, >> this would give me 2 8192 sample streams, so now, will these 2 8192 sample >> streams be the input of the subsequent FFT core ? I.e the number of inputs >> must be 1 and the number of input streams must be 2 ? >> >> Kindly clarify ! >> >> Mugundhan Vijayaraghavan >> Junior Research Fellow >> Indian Institute of Astrophysics >> -- >> the giver of moksha >> > > -- the giver of moksha
