From: Jamie McCallum <Jamie.McCallum_at_email.protected>
Date: Mon, 21 Oct 2013 11:51:00 +1100

Hi Shinji,
        The quick answer for UTas/AuScope compatibility is that if the VDIF
data format is ok for DiFX, it should be fine for us. I have a question
about the DVP though - With the DDC mode, are you able to select a
subset of the 32 USB/LSB channels to be recorded or will it always
produce a 32 channel stream? I know that the latter is the case for the
DBBC using the Fila10G.
        One other thing with the diskpacks - the Mark5C uses the same diskpacks
as the mark5B systems and the recorded files can be read back on a
mark5B+ using fuseMk5. I was able to record at 2 Gbps onto a single
diskpack (normally rated at 1 Gbps) without problems though this isn't
recommended, especially for long scans. I haven't tried dual-bank mode
with the mark5 units yet, and I'm not sure if the read-back is compatible.
Cheers,
Jamie



On 16/10/13 14:09, Horiuchi, Shinji wrote:
> Dear LBA observers,
>
> At Tidbinbilla we’ve recently installed a new JPL built VLBI digital
> backend called the Deep Space Station VLBI Processor (DVP). The new
> system is adopting CASPER/ROACH and Mark5C, similar to the NRAO/Haystack
> model, and is able record data up to 2Gbps. We succeeded to detect
> fringes for VLBI experiments within DSN at 1 and 2 Gbps recording rates
> using this system. Now JPL wants to remove the existing Mark5A recorder
> at Tid after the next 6 month ‘soaking’ period from now to convert it to
> a Mark5C as a spare across DSN.
>
> Then the questions for you are:
>
> 1)Should the new DVP/Mark5C system be sufficient/compatible to observe
> some of LBA observations at Tid using Mark5A, such as the v271 series
> for Leonid and some others, e.g. for Yuri Kovalev, Oleg Titov, and
> Michael Bietenholz as we did in the past? With the DVP we can record up
> to 2Gbps, so we can increase sensitivity if we establish the use of the
> new system for LBA. We need a fringe test if we decide it’s feasible. In
> that case, can anyone provide us a Mark5C diskpack to be used for LBA?
>
> 2)If we should keep the existing Mark4-DAT & Mark5A backend for LBA
> experiments, is anyone able to provide us an unused Mark5A module? Do
> you think it’s worthwhile?
>
> 3)If none of Mark5C and Mark5A options as mentioned above is possible,
> how bad is living only with the LBA-DR at Tid for the next several
> years? We can record fine up to 512Mbps, which I think the maximum data
> rate for any LBA stations to support. Perhaps only issue for Tid with
> only the LBA-DR is limited number of IFs for experiments that require
> wide frequency ranges.
>
> For your information, attached is a VLBI2010 Receiver Back End
> Comparison written by Bill Petrachenko and distributed earlier this year
> to the IVS community (see the part for ‘JPL DBE’) .
>
> Tips for DVP Data Format: We don’t support Mark5B-emulated data. We
> write VDIF format to the Mark5C disk packs. We can output 16 Complex
> I/Q Channels, or 32 USB/LSB channels. Each data packet contains data
> from all channels. We can record up to 2 Gb/sec on one disk pack.
>
> Any your feedback would be appreciated!
>
> Chris and Cormac, I expect your inputs from correlators perspective.
>
> People from U-Tas, what about the case also for the
> Tid-AuScope/Hobart/Ceduna alone VLBI?
>
> Regards,
>
> Shinji.
>
> ------------------------------------------------------------------------
> *Note:*
> If you received this email in error, please notify the sender
> immediately and delete the email and attachments. This email may contain
> private or sensitive information. Any forwarding or dissemination of
> information, other than by entities directly addressed in this email is
> prohibited. The views expressed in this email do not necessarily reflect
> the views of CDSCC or its business partners. The organisations accept no
> responsibility for any virus that potentially could be transmitted in
> this email, however all email is scanned prior to being transmitted.
Received on 2013-10-21 11:51:24