From: Horiuchi, Shinji <shoriuchi_at_email.protected>
Date: Wed, 16 Oct 2013 14:09:03 +1100

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.

 


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Received on 2013-10-16 14:09:09