On 10/26/2020 10:38 AM, Jack Hickish wrote:
Hi Gareth,
On Mon, 26 Oct 2020 at 12:49, Gareth Callanan <[email protected]
<mailto:[email protected]>> 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.
These are also used by a few other Berkeley and Berkeley-adjacent
projects -- Breakthrough @ Parkes, the ATA. There also used by Caltech
in the DSA. Possibly some other folk have them
I've been working with a loosely-organised group of folks on weekend
"hackfests" (remotely) at the ATA for the last several weekends, and there
is now preliminary support in Gnu Radio for SNAP boards thanks to one
of the team members. But in addition to that, we're developing
tooling to allow USRPs to be used for some of the work at ATA, and
getting GPU support working in Gnu Radio as part of that work.
Now the USRPs we're using (N320 and N321) can sample at a maximum of
250Msps, with two channels per unit.
The team has done interferometry observations of many of the "usual
suspects" (Virgo A, Cass. A, Cygnus A, etc) mostly as a way of
calibrating the precise antenna positions, to allow uture precision
synthesis imaging projects.
My focus was on debugging my SDR-based pulsar code, and making sure it
produced filterbank files compatible with "the usual tooling".
We made parallel observations using both a SNAP board and USRPs.
1. 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.
2. 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.
At the ATA we're pursuing a system using the HTG ZRF16 RFSoC platform.
There are a bunch of Commercial RFSoC platforms, at various price points.
The SKA-Low project was once looking at building a custom RFSoC
platform. They also already have the Kintex Ultrascale iTPM which has
32 onboard ADC channels.
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)
For the Caltech LWA352 system we're using a SNAP2 (dual FMC) with a
custom ADC card. I believe a few people are experimenting with fast
ADCs on FMC carriers with the VCU118/128. There are _lots_ of
commercial platforms which would support FMC ADCs. The Institute of
Automation (designers of the SNAP2) have a variety of FMC ADCs they
use on their projects with various combinations of number-of-inputs
and bandwidth / sample rate.
Personally I think most deployments in the future will be on platforms
which support 100G, so I can't imagine there will be a huge number of
SNAPs used in the coming years.
Just my random musings,
Jack
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 "[email protected]
<mailto:[email protected]>" group.
To unsubscribe from this group and stop receiving emails from it,
send an email to [email protected]
<mailto:[email protected]>.
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 "[email protected]" group.
To unsubscribe from this group and stop receiving emails from it, send
an email to [email protected]
<mailto:[email protected]>.
To view this discussion on the web visit
https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAG1GKSkz1K6DtBP_C_1B6HOTx4D0crCb21O1SKM3k8ps2U_r%3DQ%40mail.gmail.com
<https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAG1GKSkz1K6DtBP_C_1B6HOTx4D0crCb21O1SKM3k8ps2U_r%3DQ%40mail.gmail.com?utm_medium=email&utm_source=footer>.
--
You received this message because you are subscribed to the Google Groups
"[email protected]" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion on the web visit
https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/5F96FCDD.1090904%40gmail.com.
