Folks I am implementing the ROACH "polyphase" method w/ pfb_fir and fft_wideband_real.
In simulation, nothing seems to come out: all zeros...Do these fft blocks simulate correctly? Question on FFT Say we have 4 input streams, that is, 4 lines of data of one data stream divided into 4 busses that are decimated by 4. So sample rate of whole stream is 512MHz, and sample rate of each decimated stream is 128MHz. This is the normal output from the 4x MKID ADC, where the data is divided into 4 streams. We connect these streams to FFT inputs, assuming a 4K FFT. What will the sample rate of each bin be? Will it be 128MHz/ 4096, or is there more delay and some time domain data is missed? Also, what does sync_out do? I assume it is high for valid FFT coef. data output, but is there any way to trigger on the start of a new FFT coef. set? I guess we have to make a counter to count bins, and hope the counter stays in sync w/ FFT output? Also, what is difference between "simultaneous streams" and "simultaneous inputs" when setting up the FFT? Tim Madden
