Hi all Thanks for all this feedback, it has been very useful and informative. At the moment we don't have a specific array in mind. At SARAO we are busy in the initial design stages of a new correlator with both the F- and X-Engines implemented on a GPU. We are hoping that the short software compile times will make it relatively easy to deploy a correlator to an array with an arbitrary number of antennas very quickly.
The main "time to science" bottleneck when it comes to the backend that I can see will be the digitiser(conventional GPU servers don't have FMC connectors!). To be able to deploy our new system anywhere, we would need a readily available ADC board that receives data from the ADC and outputs it as SPEAD formatted ethernet streams. We have no plans to implement something like this at the moment as MeerKAT already has digitisers but I want to know the options available for when we have these discussions with other correlator teams. Thanks to Dan for the note on the inability of the ZCU111 to sync with other boards, I was unaware of this and it is a useful thing to keep in mind. Is the ZCU216 being casperised? SNAP2 looks like it could be quite versatile and if I remember correctly, it has already been casperised? Although as Jack says, 100 GbE may be the way to go in the future, 40 GbE seems to be disappearing. Additionally SNAP2 does not have FMC+ which could be an issue for the higher bandwidth facilities. However plain old FMC itself does give you lots of options. SNAP still seems to be the best choice for a wide variety of applications at the moment considering it has already been casperised and deployed. But I will also watch out for more information on the board mentioned by Lincoln. I have heard murmurings of the need for such a board. Gareth Callanan Digital Signal Processing Engineer South African Radio Astronomy Observatory(SARAO) On Mon, Oct 26, 2020 at 8:32 PM Dan Werthimer <d...@ssl.berkeley.edu> wrote: > > hi gareth, > > can you tell us a bit more about your project? > sample rate? number of ADC bits? number of ADC's? ADC analog bandwidth > ? > then people might be able to provide better advice. > > some random thoughts: > > you probably know the SNAP board has a ZDOC connector on it, > so the old CASPER ZDOC ADC's can plug into SNAP (except for the dual ZDOC > 64 ADC board), > see ADC list at > https://github.com/casper-astro/casper-hardware#casper-hardware > but casper doesn't have all the yellow blocks for all of these ADC boards > to run on SNAP - > you might need to do some yellow block development, depending on which ADC > board you want. > > if this is for a correlator, and you want to use an RFSOC board, make sure > that board > can sync with other RFSOC boards so all the boards sample at the same > phase. > the 8 input ZCU111 board can not sync with other boards, but the ZCU216 > can. > i think most of the newer commercial RFSOC boards can sync. > mitch has evaluated several of RFSOC boards and has tested a few boards > for sync capabiltity. > > if you want a cheap 4 Gsps dual 12 bit RFSOC board, xilinx has a $2K RFSOC > education board > they said they could make this board available at high quantities to > casper collaborators. > > there's a quad 15 Gsps 4 bit FMC ADC board developed by jonathan > weintroub's group and rick_raffanti. > wei liu is working on a yellow block for this board. > and there's a single 15 Gsps 4 bit board developed by ASIAA. > > there is a dual ~5Gsps, or single ~10Gsps ~12 bit TI ADC board developed > by JPL. > there's a dual 10.6 Gsps ~10 bit AD ADC board under development at GBO. > > best wishes, > > dan > > > Dan Werthimer > Marilyn and Watson Alberts Chair > Astronomy Dept and Space Sciences Lab > University of California, Berkeley > > > On Mon, Oct 26, 2020 at 5:50 AM Gareth Callanan <gcalla...@ska.ac.za> > wrote: > >> Hi Casper Community >> >> Now that roach2 has been deprecated, I have been wondering where the >> CASPER community is heading in terms of future ADC work. >> >> As far as I can tell there are three options available: >> >> 1. SNAP boards - The SNAP boards seem to support the largest number >> of options 12 x 250 Msps/ 6 x 500 MSps or 3 x 1000 Msps. SNAP is used by >> HERA, but I don't think it is used anywhere else. >> 2. SKARAB and the SKARAB ADC - The SKARAB ADC can sample at up to 3 >> GSps. From what I can tell, it does not seem to be widely used. I imagine >> it would be quite an expensive configuration. >> 3. ZCU111 RFSoC - The ZCU111 RFSoC seems to be a good board for >> experimentation, but if we wanted to build a many antenna array (N > 100), >> XIlinx may not be quite able/willing to provide us with that many dev >> boards. >> >> Alternatively, maybe there is some cheap FMC ADC out there that could >> make everyone happy? (Although then we would need to find an FMC carrier >> card) >> >> From the options available, it seems to me that SNAP is the board that is >> most likely to be deployed in a large array, and the ZCU111 board is what >> is most likely to be used in labs/small arrays. >> >> Is that a correct read of what is available? Or are there other projects >> in the works? >> >> We have cheap COTS options for building X/F-Engines. As far as I can >> tell, an easily accessible ADC board is the main bottleneck to quickly >> prototyping/building a correlator. >> >> Gareth Callanan >> Digital Signal Processing Engineer >> South African Radio Astronomy Observatory(SARAO) >> >> -- >> You received this message because you are subscribed to the Google Groups >> "casper@lists.berkeley.edu" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to casper+unsubscr...@lists.berkeley.edu. >> To view this discussion on the web visit >> https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CA%2B1nFZTu1S3E%3DaH_KtvPE722UdW49HD0b3YeB07mZbGSGT_7Vw%40mail.gmail.com >> <https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CA%2B1nFZTu1S3E%3DaH_KtvPE722UdW49HD0b3YeB07mZbGSGT_7Vw%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups " > casper@lists.berkeley.edu" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to casper+unsubscr...@lists.berkeley.edu. > To view this discussion on the web visit > https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAGHS_vF6a5wGUy1%2Bp2MPPWO52uyBxouqDSZZ58tWcCpuw0D1qA%40mail.gmail.com > <https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAGHS_vF6a5wGUy1%2Bp2MPPWO52uyBxouqDSZZ58tWcCpuw0D1qA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "casper@lists.berkeley.edu" group. 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