This is an old revision of the document!
ASKAP extensions useful to VLBI are:
|08 9923 7700||MSF - Gemma|
|08 9923 7750||MSF - Shaun Amy|
|08 9923 7766||MSF - Suzy Jackson|
|08 9923 7900||MRO - main site phone|
|08 9923 7961||MRO - control room|
|08 9923 7965||MRO - Electronics room|
|08 9923 7958||MRO - Desk 4|
|08 9923 7950||MRO - Manager|
|08 9923 7979||MRO - 1st Aid|
|08 9923 7929||MRO - Ant29 hut|
|08 9923 7970||MRO - old site hut?|
|08 9923 7973||MRO - Lunch hut?|
From CSIRO phones replace prefix with just 99 and then the 4 digit extension.
In the beginning of VLBI operations at ASKAP 2010-2013, all observations were done on ANT29 (CETCI #1), from an installation in hut29 next to the antenna. Connections were made via direct cabling from the hut to the antenna as needed.
Since the start of 2014, all VLBI equipment has been moved to the shielded room in the main ASKAP control building. Communication with the antennas is via RFoF connections for the RF and 100 MHz reference (for the X-band Rx). Communication with teh antenna is via the standard C&M network (18.104.22.168xx, where xx is the CETCI antenna number).
From May 2014, VLBI operation has moved to antenna Ak32 (CETCI #26).
ASKAP antennas are accessed for VLBI via a VNC session on the Curtin Recorder (cira10) housed in the shielded equipment room at the ASKAP site at MRO. The vlbi recorder is on a 1 Gbps link to the routed CSIRO network. It can now be accessed directly as cira10.atnf.csiro.au, with both ssh or VNC from ATNF networks.
To run the antenna for VLBI, the directory should be set to “askap/run” and commands can be run in separate xterms.
The driver task “askap_drv” needs to run first for communicating with the antenna, and then the other tasks are started. This can be done by:
This starts askap_drv and the antenna gui in one step. It also displays the “askap_drv #n” session is a separate xterm to monitor messages.
This command also loads the correct pointing parameters from the master pointing file antenna_pointing.data in askap/run.
* N.B. If GUI crashes you MUST also kill the message window before restarting!! Otherwise the connection may not be properly established.
For vlbi observing via the schedules you need:
(Older versions such as vlbi_drv and vlbi_drv_new are available but their use is not recommended).
The schedules are in sub-directory askap/sched. To run try:
The main antenna control is run from the gui. Essential commands that can be typed in the command window are:
(Note: if the telescopes is having problem switching the drives, a sequence of drive_off and then drive_on often fixes things)
One can track a source from the gui e.g. for fringe checks.
* During tracking make sure that the “stack” button is decrementing from about 38 to 1 in cycles. You can also monitor this in the askap_drv window.
For debugging problems other useful commands are:
For pointing runs, a “spot” option is available instead of “track”. This does scans in a cross pattern, and tehse can be used to determine pointing offsets, especially for the X-band Rx.
The “scan” option allowas for controlled scans through a source.
The vlbi schedule for askap is a .psn file similar to Parkes. Normally this will have been already generated and copied to cira10. If you need to generate this from the vex file in the vlbi ftp area one needs to run “vex2psn.pl -askap <vexfile>” and scp to cira10 in the area askap/sched. e.g.
in the v252ab area would create the .psn file, Note the _ak in the filename, so as to not confuse with the .psn for Parkes.
In another window in the askap/run area type “vlbi_drv_mk2”. It will ask for the schedule name. It should be provided by full path name e.g. “../sched/v272ab-ak.psn”. Or the schedule name can be provided in the command line (only for the _mk2 version of the driver).
It should then run for the duration of the schedule and the telescope should slew and track at the appropriate times. If a source has set or has not risen the schedule will report “sleep” and will wait till the next scan.
N.B. 1: If you stop vlbi_drv with ^C it can hang the gui and/or crash askap_drv. If you need to stop vlbi_drv best use the “q” command in that window. But q does not always work so ^C can be used if needed.
N.B. 2: If schedule is started early and sources are below horizon, vlbi_drv behavior may be uncertain. Watch closely and restart schedule if necessary.
N.B. 3: Even when vlbi_drv is running, the telescope can be stopped from the gui. If you do that, it is not clear if the schedule picks up ok again. vlbi_drv may need to be restarted.
Note that the system use “automount”. Currently it is configured with two data disks /mnt/raid_0 and /mnt/raid_1. You may need to “cd” into the directories before they seem visible.
Before recording data the directory should be created in /mnt/raid_0 e.g “mkdir v272ab” and then cd to that area before starting the recording program px14_record (similar to vsib_record). To run a quick check one can use e.g.
N.B. For the X-band Rx on Ak32 (since May 2014) you may have to use “-v 18” to get the rms values between 1000 and 2000 counts.
Correct operation can be checked by running fauto with say “-n 512 -tint 1” on one of the recorded files.
Real-time fringe-checking is done for all LBA setups and will be the primary means of verifying correct operation. It is run centrally for all telescopes.
For production recording longer files should be run and an output name should be given e.g.
will create the default 1 min length files for 12 hours.
NOTE 1: To stop px14_record it is recommended to use ESC rather than ^C.
NOTE 2: When restarting make sure you use all the correct parameters e.g. the “-invert” option. Best to use up-arrow and edit the previous line appropriately.
NOTE 3: The PX14400 kernel driver sometimes gives errors like “failed to allocate DMA buffer”, and needs to be restarted. This can only be done as root. The command then is “/etc/init.d/px14400 restart” (the available commands are: stop, start, restart).
The H-maser controls the timing for vlbi in the askap shielded room. It is possible to monitor and control the H-maser via a VNC. Check with the vlbi group or Peter Mirtschin before attempting any adjustments on the H-maser.
The 1pps from the H-maser has glitched occasionally, most likely due to power cycling of the site, even though the H-maser is on 2 levels of UPS. If fringes are not found, the H-maser can be re-synched remotely.
The difference of the 1pps from the H-maser and the 1pps from the GPS (the ntp server in the main comms rack) can be monitored with a local timer-counter, but this can only be done manually.
The ATDC computer provides a station clock. It is synched to the GPS and the 5 MHz reference from the H-maser. It counts its own 1pps and this can be used to synch the samplers. This clock is displayed on the station and the tick-phase is monitored and logged.
BUT it has been playing up recently (March 2012) and it should be checked out before used.
The sampler in the VLBI computer expects a 64 MHz IF at 288 MHz (256-320 MHz. It uses a 128 MHz sampling clock provided by a SML 01 synthesiser (output level at 5 dBm), locked to a 10 MHz external reference from the H-maser. Make sure that “ext ref” is showing.
The LO for the L-band is provided by an Agilent at the antenna pedestal. This is locked to a 10 MHz external reference from the H-maser. Output RF level needed is 11 dBm. Again “ext ref” MUST be showing.
These filters are inside the conversion box and cannot be easily swapped. If both 18cm and 21cm are used in one session, the wide filter MUST be used.
The X-band Rx has a fixed 1st LO at 7.1 GHz, locked to a 100 MHz reference signal for the H-maser. This is housed in the Rx box with the feed.
The 2nd LO is provided by the L-band system conversion equipment, as detailed above.
The Agilent providing the L-band LO is setup to remember its last state and recover to that on power-up.
The Agilent synthesiser can be controlled via Ethernet. It required the installation of a local ethernet switch at the antenna pedestal and the use of an ethernet-to-GPIB dongle.
The software to control the synthesiser is called locontrol.pl and takes options on the command line i.e.
The -lfreq and -xfreq commands report the LO that has been setup and also if the band is inverted or not. The only inverted band at present is when lfreq is around 1.6 GHz. If the band is inverted do not forget to set the -invert option in px14_record.
It is prudent to sent a “status” command every time setup changes are made.
Other options are:
These should be used with CAUTION.
The antenna status can be monitored via Monica, running at the ATCA.
To get to Monica, an ssh tunnel is needed, from within a screen session, logged on as vlbi. The command for the tunnel (e.g from hydra) is:
ssh -R 8051:monhost-nar:8051 vlbi@cira10
To setup (or reconnect) to the screen session run the following
ssh vlbi@hydra screen -ls
If no sockets are found then run
screen ssh -R 8051:monhost-nar:8051 vlbi@cira10 ^a d (Control-a d)
this leaves the screen session detached so you can log off and leave it.
If the output of
screen -ls lists one (or more) sessions then you can reattach using
if, for example, the ssh tunnel has closed you need to restart. Detach with “^a d” when done
Monica also enables monitoring via the LBA web monitoring page at