To run a VLBI experiment, a number of independent programs need to be run. This include a program to control the telescope and IF setup, controlling the DAS and the LBADR disk recorder.
The DAS is controlled by a gui. Log onto the machine running the DAS control and run
> das1 & > das2 &
A gui is needed to control each DA individually. For each experiment determine which DAS profile is needed (the wiki guesses the profile, but this is not guaranteed to be correct).
File→Loadmenu item, then selecting the correct profile in the file browser.
Monitor IF Level status bar. The this should be roughly mid range. If it goes of of range the DAS gui will complain (see below) and the attenuation (or catie gain at ATCA) will need to be adjusted.
Note: If the control buttons are greyed out, it might be that a lock file still exists (either the DAS crashed without removing this, or another DAS process is still running). If you are sure there is not another DAS process running, remove the lock file by hand.
The LBADR is a disk based recorder based around a standard PC. Data is recorded usually to external Xserve RAIDs, but can also be recorded to removable IDE disks or internal disks.
There is no need to shutdown the host PC to change Xraid disks. The following steps are needed to swap disks
> df | grep xraid > umount /data/xraid0
(for example, do all mounted disks)
> mount /data/xraid0
> /etc/init.d/recorder_server restart
Recording is make by a program called
vsib_record on the LBADR, which is controlled by a Tk gui
cdisko2. Ssh as vlbi onto the LBADR recorder and run:
Fill in the following fields, based on the notes on the experiment wiki:
Scheduled startbutton, click “Now + 1m” then set the start time to the recording start time. If starting the recorder late, or when changing disk partition during an experiment do not use the scheduled start.
To determine the correct channel selection, choose either 1-4 or 1-8 for 4 or 8 channel setups (as per the wiki). For other selections, the wiki should give the channel selection required.
The Xraid disks are “sliced” into 2 or 3 sections (due to limits in the Linux kernel). The slices can record 6.5 hrs of data at 512 Mbps or 13 hrs at 256 Mbps. Normally record 6 (or 12) hours to a single slide. However always set the duration to be longer than the indented recording time in case you are late doing the change. If possible try and change disks during slew time.
To actually do a disk change, while recording
Scheduled startis turned off
The cdisko manual is at http://www-ra.phys.utas.edu.au/~jstevens/vsib/vsib_control_31.html
|Default Recorder||DAS control|
If remote, add “-ext”, e.g cavsi1-ext