If you take a look at the pocket correlator design (tutorial 4), you'll find that it does four inputs of 400MHz bandwidth (800Msps). I think it has 4-tap PFBs with 1024 channels by default, which fits into a ROACH-1. If you forfeit two of the inputs, you should be able to get at least twice the channel resolution. If there's BRAM left over, you should be able to get even more.
Jason On 29 Aug 2012, at 11:19, Tom Kuiper wrote: > Thanks for that, Jason! It is very timely. The reason I went down this path > is because I have a spectrometer design, by Joseph Trinh, which takes a > slightly different approach to bram access and so I could not use the > katcp_wrapper which I'd been using with your 16K spectrometer. He'd offered > to modify it but I thought it cool to try the file access I/O. I think as a > result of this exchange, I'll ask Joseph to modify his design and I'll start > using pyro. > > I hope he can squeeze it into a ROACH-1. He's got a 2x1024 spectrometer > design for me now but had to drop the PFBs because of insufficient resources. > I'm asking him to try 2x512 with PFBs. Does anyone already have something > like that? > > Next time around we'll use ROACH-2 but at the time we placed the orders we > weren't sure that the support for that would evolve fast enough to meet our > deadline (next month). > > Cheers > > Tom > > On 08/29/2012 01:09 AM, Jason Manley wrote: >> On 29 Aug 2012, at 02:44, Adam Barta wrote: >> >>> You could also try an ssh port forward to the katcp port ssh -vNL >>> 7147:roach:7147 gateway >>> Then use the katcp interface to read / write the registers. There is a >>> katcp_wrapper.py in the corr library >>> >> I would like to re-inforce this suggestion if you need SSH tunnelling >> through a firewall. A general word of warning to the CASPER community, which >> we also explained at the recent workshop... >> >> MeerKAT will not be supporting filesystem-level access in future boards >> (quite possibly starting with ROACH-2 already) and so, unless someone else >> in the collaboration picks it up, you'll be on your own if you write custom >> software to run on the PPC/BORPH because new platforms might not even run >> BORPH at all. There are a number of reasons for this decision, one being >> that we've run into performance limitations with BORPH, but also that it's a >> big overhead to port and debug and to keep it running reliably. >> >> The only interface supported by SKA-SA will be through KATCP. So if you >> start using the KATCP interface now, you'll have a transparent upgrade path >> to future boards. I'd suggest you don't worry yourself too much with the >> low-level detail... this is part of what CASPER tries to abstract away to >> ease your life as an instrument designer. >> >> If you don't want to write your own KATCP interface (and who does?!), >> consider using one of the existing ones. The best developed ones are in c >> (which includes a command-line executable for a single-line, ipython-like >> interactive experience from the shell prompt if you just want to call a >> shell script with a bunch of commands), available at >> https://github.com/ska-sa/katcp_devel, or a number of CASPER collaborators >> are using the python wrapper from corr if you want to build a higher-level >> GUI application. You can find a one-page getting started guide here: >> https://casper.berkeley.edu/wiki/Corr >> >> Jason >> >> > > > -- > I or me? http://www.oxforddictionaries.com/page/145 > >
