hi ross, we never got our roach1 design working at 5 Gsps, although we never tried. our design goal was 3 Gsps.
if you don't need a lot of spectral channels, you could probably fit into roach1 a decimate by 16 design, and clock the fpga at 5 GHz / 16. if you need a lot of spectral channels, you'll need roach2 instead of roach1. warning: it will take some time and advice by people skilled at plan ahead to get the clock rate up to 5 GHz / 16. make sure you choose the version of the adc that decimates by 16 if you want to clock at that high rate. best wishes, dan On Tue, Feb 12, 2013 at 1:02 PM, Ross Williamson < [email protected]> wrote: > Hi Glenn, > > Thanks, I was being a tad blase regarding Nyquist/sampling rates. I think > if we can operate at 2.5GHz BW on each channel using the ROACH-I then we > should be fine - at least as a good proof of concept. > > Ross > > On Tue, Feb 12, 2013 at 12:58 PM, G Jones <[email protected]> wrote: > >> Hi Ross, >> One point to clarify, the 5000 refers to the samping rate, not the >> total bandwidth. So a single ADC1X5000 demux 1:2 will give you 5000 >> Msps at 4 bits per sample, allowing you to sample signals up to 2.5 >> GHz bandwidth. With a single board, you'd need to put the board in the >> mode that instead acts as two ADCs each providing 2500 Msps at 4 bits >> per sample, hence you'd be able to correlate two signals each of up to >> 1.25 GHz bandwidth. With two ADC cards, you could correlate two 2.5 >> GHz BW signals. >> >> Glenn >> >> On Tue, Feb 12, 2013 at 3:53 PM, Ross Williamson >> <[email protected]> wrote: >> > Hi All, >> > >> > I'm new to CASPER/ROACH boards and so apologies if this is obvious. We >> are >> > hoping to build a simple 2-channel correlator with a fairly high >> bandwidth. >> > We are in the process of ordering a ROACH-1 board and I was thinking of >> also >> > purchasing the ADC1X5000-8 ADC - A few questions: >> > >> > 1) Should I even be looking at an ADC1X5000-8 for use as a correlator? >> > 2) I believe I need the DMUX 1:2 version to work with ROACH-1 board - is >> > that correct? >> > 3) I should be able to run 2 channels at 2.5GHz 4bits with a single >> board - >> > correct? >> > 4) If I wanted to could I purchase another ADC1X5000-8 and try and run >> with >> > 5GHz bandwidth on each channel using the ROACH-1? >> > >> > Best regards, >> > >> > Ross >> > >> > -- >> > Ross Williamson >> > Research Scientist - Sub-mm Group >> > California Institute of Technology >> > 626-395-2647 (office) >> > 312-504-3051 (Cell) >> > > > > -- > Ross Williamson > Research Scientist - Sub-mm Group > California Institute of Technology > 626-395-2647 (office) > 312-504-3051 (Cell) >
