Monitoring the calibration

Once cycling, the EARLY program will start to collect data, displaying the data as it gets it. You should also be very wary if you get any warning messages, such as:

WARNING: Not all antennas/IFs will be calibrated
11CD
22CD
33CD
44CD
55CD
66CD
Waiting for CAOBS to start

etc.

This may be what you want but, in general, we like to check early normal calibration on both frequencies. If the EARLY program can't find all the auto-correlations it expects for 2 frequency, 6 antenna operation, it will warn you, but still proceed with the calibration. If you are using the recommended FULL_128_2 correlator configuration file, you should not see any warning messages at this stage.

You can also keep track of the data collection using VIS. A set of sample commands to give a good display are:

VIS$>$hist 20m ; sel ab,cd ; d-t ; scale d

which gives, respectively, 20 minutes of history, showing the cross-products as delay versus time, with auto-scaling. Obviously, you might want to reset things first with a reset command.

Figure K.3 shows a sample VIS display

Figure K.3: Example of a vis delay plot during early/normal calibration.