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 <d...@ssl.berkeley.edu> To: Bill Petrachenko <wtpe...@yahoo.ca> 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 <wtpe...@yahoo.ca> wrote: > Thanks Dan. It sounds like the Kat-ADC is probably best for us. > > -Bill. > > ________________________________ > From: Dan Werthimer <d...@ssl.berkeley.edu> > To: Bill Petrachenko <wtpe...@yahoo.ca> > Cc: Casper <Casper@lists.berkeley.edu> > 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 <wtpe...@yahoo.ca> 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. > >
