From: <stingay_at_email.protected>
Date: Thu, 15 Jun 2006 11:51:47 +1000 (EST)

Dear All,

I largely agree with all of the technical comments that Chris made in his
last email, regarding the difficulties with PCFS at the ATNF antennas. He
is much more aware of the underlying issues than I am. I am aware of the
details of some of the issues and this alone is enough to tell me that
using the PCFS for the ATNF antennas would be very difficult.

Ultimately I defer to Chris on these issues, since he has been working on
them for a long time.

However, I would like to encourage Simon and Jamie to scope out the issues
for themselves and investigate the feasibility of using PCFS at the ATNF
antennas. I think it would be an excellent thing for Jamie to spend some
time at the ATCA, Mopra, and Parkes and talk to Euan, Dion, and Simon(?)
about these issues. A report back to the vlbiobs group would be extremely
useful.

If it were only the Tsys logging that was solved using PCFS, then this
would be highly useful in itself. Personally, I think that antenna
control will be so difficult that it is not worth the effort.

However, like I say, I'd like to see Simon and Jamie scope it out and
report back on what they think is possible. If the ARC money is for these
activities, let's use it.

Cheers, Steven

##=====================================================##
Dr Steven Tingay stingay_at_astro.<!--nospam-->swin.edu.au
Swinburne SKA Project Leader
Associate Professor

Centre for Astrophysics and Supercomputing
Swinburne University of Technology
Mail No H39
P.O. Box 218, Hawthorn, Vic. 3122, Australia

ph: +61 3 9214 8758
fax: +61 3 9214 8797

http://astronomy.swin.edu.au/ska
##=====================================================##

On Thu, 15 Jun 2006, Tasso Tzioumis wrote:

>>>
>>> Hi All,
>>>
>>> Yesterday we spent a lot of time discussing the issue of logs
>>> and calibration data and the decision that was arrived at was to try
>>> and fix the messy system currently in place. I'd like to make an
>>> impassioned plea to instead use these resources to properly implement
>>> PCFS
>>> control at Parkes, Mopra (and the ATCA if possible).
>>>
>>> The executive summary (for those without the time to read a long
>>> email) - it will make our operations more reliable and for a small
>>> effort it will dramatically improve our user support (and bring us
>>> into the 1990s).
>>>
>>> Here is the long-winded _lots_ of reasons why I think we should do this :
>>>
>>> - The PCFS was designed to run VLBI experiments; control the antenna,
>>> recorder and ancillary hardware and log system information such as
>>> Tsys,
>>> weather etc.
>>>
>>> Whenever I go to ATCA, Mopra, Parkes for other types of observing,
>>> one
>>> piece of software controls the telescope and observing hardware
>>> (correlator or whatever). No other user group would accept such
>>> a cobbled together, anachronistic and archaic observing
>>> system - why
>>> should we?
>>>
>>> - The PCFS is the _world_ standard for VLBI observing - the EVN uses
>>> it at all its telescopes, the geodetic community, even NASA!
>>>
>>> - If we can make the PCFS control the antennas, recorder, log the
>>> Tsys and weather then we have the unthinkable - one log from
>>> each telescope all in the same standard format.
>>>
>>> At the moment we have a situation where an ATNF student supervised
>>> by one of the members of this group, has been waiting months to
>>> get the basic information they need to calibrate their data. No
>>> wonder we only get proposals from black-belt VLBI experts,
>>> who else
>>> has any chance of being able to reduce their data without Herculean
>>> effort?
>>>
>>> - As part of the ARC e-research grant, Jamie is currently working on
>>> software to enable the PCFS to operate the disk-based recorders.
>>> This system is compatible with disko. I think that we should
>>> aim
>>> to view disko as being equivalent to the S2 front panels -
>>> something that you can use to control the recorder if necessary,
>>> but generally best left untouched during an experiment (so that
>>> the recorder commands are logged by the PCFS). I'm pretty
>>> sure it
>>> should also be possible (although perhaps a little messy) to have
>>> commands/comments entered into disko logged by the PCFS (if thats
>>> what people _really_ want).
>>>
>>> So how do we achieve this? Perhaps I'm being naive and lack vital
>>> knowledge about the detailed operation at some telescopes, but I think
>>> there are fairly simple solutions that would only take a couple of days
>>> for people with the right expertise.
>>>
>>> To control the antenna using the PCFS all you need is a program running
>>> on some machine at the observatory that can do three things
>>> - communicate with the PCFS via a standard TCP/IP socket
>>> - slew the antenna to a location in RA/Dec (you may also want to be
>>> able to control the antenna drives)
>>> - determine whether the antenna is at that location or not
>>> Once you have that in place it is a matter of a few minutes work to
>>> modify the antcn.c stub program in the PCFS. If this can't be done at
>>> the ATCA, why not, the control systems have just been rewritten and this
>>> is a piece of basic functionality?
>>>
>>> At the ATNF sites the system temperatures are automatically logged
>>> into files somewhere on some machine. To get that information into
>>> the PCFS you need another simple program that when requested reads the
>>> most recent value from that file (you might have a simple client
>>> program on the machine where the Tsys information is logged say) and
>>> writes it to the log. The weather information can be done the same way
>>> (as it is at Hobart).
>>>
>>> The antenna control in particular I see as being very useful in the
>>> near future. At slow slewing antennas like Parkes, during a phase
>>> reference experiment you might spend as much as 50% of the time
>>> slewing between sources. We are currently disk limited and so if we
>>> can reliably know when we are onsource we can significantly increase
>>> the duration, or number of experiments we do by not recording when
>>> offsource. This will also save network bandwidth when we move to real
>>> eVLBI.
>>>
>>> Finding the people with the time and expertise to do these types of
>>> jobs is always difficult, but given the importance of this UTas will
>>> help with this as part of the e-research project. Phil, John, if you
>>> can identify the appropriate people at Parkes & Mopra and arrange for
>>> them to have a couple of days to work on this, we can send Jamie up to
>>> work with them on the PCFS and implementation side. How does that
>>> sound to everyone?
>>>
>>> --
>>> Regards
>>>
>>> Simon
>>> --
>>> Simon Ellingsen : Senior Lecturer Physics & Astronomy, University of
>>> Tasmania
>>> email : Simon.Ellingsen_at_utas.<!--nospam-->edu.au
>>> WWW : http://www-ra.phys.utas.edu.au/~sellings
>>> Phone : 6226 7588 ; Area Code : +61 3
>>> (International)
>>> 6278 8636 (Home), 6226 2410 (Fax) 03 (Australia)
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Received on 2006-06-15 11:52:14