[casper] 2 input fft

[Danny Price]

G'day all

Does anyone have experience with using a 2^1 simultaneous input FFT? The 
fft_wideband_real block has a minimum of 4 inputs; has anyone ever 
modified this or built a 2 input version?

The reason I ask is that we would like to make a 0-200MHz spectrometer; 
the initial plan was clocking the ROACH at 200MHz => ADC at 800MHz, then 
dropping two of the four ADC samples. We're after high spectral 
resolution and would like to pack four spectrometers onto one board. Any 
advice?

Thanks
Danny