ATNF VLBI Wiki

The integration time already setup is shown in the camon window (use /mopra-x in camon to see all bands). If it needs to be reset use: > newcain cycle <sec> - to setup the integration cycle time in secs. Default cycle time has been 10s but mm observers often use ~2sec. For VLBI 5sec may be more appropriate. To see what else òÀÜnewcainòÀÝ can do just type òÀÜnewcainòÀÝ without any parameters and it will give you a list of commands. CAUTION: Please only use òÀÜnewcainòÀÝ if you really understand what you are changing.

attest can be used to set attenuation, focus the receiver and stow the antenna. Run attest by logging into bigrock as observer and running

> attest &

Generally automatic attenuation in vlobs should be turned off. It often gets the wrong value and SDO measurements saturate, giving no Tsys values. Select the òÀÜattenòÀÝ tab in attest.

Coarse attenuators should be set to òÀÜ0 0 0 0òÀÝ for L and S band and òÀÜ1 1 1 1òÀÝ for everything else. To adjust the fine attenuators, check the current settings show in camon (attest does not display the current settings) and choose the appropriate values. Then click òÀÜgoòÀÝ. If the attenuators are set to an appropriate value, the DAS IF selev and offset should be roughly midrange, GTP should be ~1.0-4.0 and SDO should > 0.0 and < 4.9, if the Tsys value seen by vlobs are not be zero.

For the 22 GHz receiver with the quarter-wave plate for circular polarisation the setup has mm-attenuators at òÀÜ 7 4òÀÝ (check in Monica that the C26 levels are below 15 V), the coarse attenuators are set at òÀÜ2 2 2 2òÀÝ and the fine attenuators are adjusted for the right GTP and SDO levels as described above (Aug'08 that was òÀÜ4 1 2 2òÀÝ).

Each frequency has a separate focus setting. To set this, choose the òÀÜfocusòÀÝ tab in attest and move the slide to the correct value and click òÀÜGoòÀÝ.

To stow the antenna exit vlobs and choose the òÀÜstowòÀÝ tab in attest. Then click the òÀÜgoòÀÝ button.

Mopra is run by the program vlobs. This points the antenna, sets up the frequency and logs Tsys.

TCS should not be run at the same time as vlobs. Before starting vlobs for the first time, run

> killtcs

Copy the sched input file from the atnf ftp area for this experiment, e.g. v001a_Mp.com. This needs to be converted into a vlobs file. Normally these should be copied onto bigrock at ~atcaobs/sched_vlbi. atcasched is used to do the conversion. E.g.

> atcasched > @v001a_Mp.com > write > exit

To run vlobs log into bigrock as observer and run òÀÜvlobsòÀÝ. There is a startup bug, it can take dozens of times before it actually starts. If your terminal is full of garbage characters, use the òÀÜresetòÀÝ function of the terminal (middle mouse button on an xterm, or a menu option on fancy terms (e.g. Unsed òÀÜterminalòÀÝ on gnome-terms.

The main vlobs commands are:

Usually Mopra data is recorded remotely to Narrabri, onto cavsi2.

Run cdisko as normal but make the following changes:

• Select Remote Disk Recording in the recording mode selection
• Select the ConfigureòÆÒShow eVLBI settings menu item to get the eVLBI dialog
• Set the following values

Record as normal

At the end of the session (or during as well if required) you need to copy the mopra logs down to Sydney. Log onto any machine in Epping as òÀÜvlbiòÀÝ and run the command mopralog.sh

> mopralog.sh

This will invoke rsync to copy down the logs directory.