It's the same board. We were both typing response emails at the same time! Jason
On 31 May 2012, at 12:55, Bill Petrachenko wrote: > Hello Jason, > > This board sounds interesting although a full 1-GHz would be preferred. Is it > the same board that Francois described or a different board? > > Thanks, > -Bill. > > From: Jason Manley <[email protected]> > To: Bill Petrachenko <[email protected]> > Cc: Dan Werthimer <[email protected]>; Casper <[email protected]> > Sent: Wednesday, May 30, 2012 9:19:48 AM > Subject: Re: [casper] 1-2 GHz sampler > > MeerKAT's going to be using a 10-bit 1.8Gsps monolithic part. You won't quite > get 1GHz bandwidth, but 900 is close. The ADC itself will do 2.2Gsps, but the > external DMUX chip limits us to 1.8Gsps. There's another part with the DMUX > integrated that will go faster, but then you'll have to layout your own ADC > board. > > We're expecting the MeerKAT L-band ADC to be in production in a couple of > months. This part gives some pretty impressive performance. Attached are some > plots kindly provided by a non-CASPER collaborator who's played with it > (Klasie Olivier from CSIR) for the integrated ADC/DMUX version. > > But as you've pointed out, this card won't run at full speed on ROACH-1 due > to clocking limitations on the LVDS pins so we're using ROACH2s for full > speed. > > Jason > > > > > On 30 May 2012, at 14:57, Bill Petrachenko wrote: > > > OK, so it looks like I'll need to pay more attention to interleaving than I > > had hoped. I assume there are no ROACH-compatible boards that use chips > > that clock at 2048-MHz but without interleaving. > > > > Also, we're using a flexible down-converter to select 1-GHz bands anywhere > > in the 2-14-GHz range. At many sites RFI at S-band will be a problem so > > dynamic range is an issue. The chips on the ASIAA, ADC1x3000, and Kat-ADC > > all seem to drop to about ENOB = 6-bits at 2-GHz which is less than ideal. > > Using a 10- or 12-bit sampler would be preferred but it seems no > > ROACH-compatible sampler boards have been designed with 10- or 12-bit > > capability and the interface won't handle the extra bits anyway. Having > > said that though I seem to recall that you implied in your initial email > > that the ASIAA card could be used in the dual sampler mode (assuming a > > 1-GHz bandwidth) if interaced to the ROACH2 and yet the ZDOK connection for > > both ROACH1 and ROACH2 both use a 40 differential pair interface. How do > > you get the extra bandwith with the ROACH2? > > > > Yes, I did pick up that we would need the higher bandwidth filter. However, > > I also noticed that there were some plans to implement shields and heat > > sinks for the Kat-ADC. Has this come to pass or has it become apparent that > > neither are required? > > > > Many thanks, > > -Bill. > > > > From: Dan Werthimer <[email protected]> > > To: Bill Petrachenko <[email protected]> > > Sent: Monday, May 28, 2012 11:21:40 PM > > Subject: Re: [casper] 1-2 GHz sampler > > > > the kat-adc has two different front end fiilter options. > > make sure to order the filter option for high frequency. > > > > dan > > > > On Mon, May 28, 2012 at 7:19 PM, Bill Petrachenko <[email protected]> wrote: > > > Thanks Dan. It sounds like the Kat-ADC is probably best for us. > > > > > > -Bill. > > > > > > ________________________________ > > > From: Dan Werthimer <[email protected]> > > > To: Bill Petrachenko <[email protected]> > > > Cc: Casper <[email protected]> > > > Sent: Monday, May 28, 2012 8:47:45 PM > > > Subject: Re: [casper] 1-2 GHz sampler > > > > > > hi bill, > > > > > > i think all the boards you mention have analog bandwidth out to 2 GHz, > > > so they should work well for your 1-2 GHz band. > > > > > > the asiaa board is the least expensive, but this board does not have > > > programmable > > > attenuators like the Kat-ADC. the asiaa board can be used as a single > > > 5 Gsps ADC, or as a dual 2.5 GHz ADC. > > > we have used the asiaa board as a single 5 gsps adc, and it works quite > > > well. > > > but we have never tested it as a dual adc - perhaps others reading > > > this email can > > > give you advice about using it in dual mode. if you are using roach > > > I, you can't > > > get the 8 bit version of the asiaa board working at the full 5 gsps. > > > if you are using > > > roach II, you can use it at 5 Gsps. > > > > > > best wishes, > > > > > > dan > > > > > > > > > > > > > > > On Thu, May 24, 2012 at 11:30 AM, Bill Petrachenko <[email protected]> > > > wrote: > > >> I'm designing a digital data acquisition system using a ROACH1 board. I > > >> need > > >> to sample two Nyquist zones at 1024-2048 MHz. It appears that in the > > >> Casper > > >> group of products, a pair of ASIAA, ADC1x3000-8, or KatADC boards would > > >> work > > >> well and nicely interfaced to a single ROACH1 board (although the ASIAA > > >> board is not mention explicitly on the web-site). Is there any reason to > > >> choose one board over another? The gain adjustment stage is attractive on > > >> the KatADC but the performance of the ADC1x3000-8 chip seems marginally > > >> better at 2-GHz input frequency. The e2v chip seems less established than > > >> the National chips. Is interleaving or calibration an issue for any of > > >> the > > >> chips? > > >> > > >> I'd be grateful for any opinions on this. > > >> Thanks, -Bill. > > > > > > > > > > > > >
