Australia Telescope Compact Array

CAinit - Compact Array Initialization

CAinit is a program for initializing the integration cycle parameters for the Australia Telescope Compact Array. It provides several functions, the two most common for the average user are: Restarting the integration clocks and setting integration cycle parameters.

Restarting the integration clocks

After a serious disruption to observing (e.g. loss of LO) it may be necessary to restart the integration clocks.

Setting integration cycle parameters

The following parameters define the Compact Array integration cycle. These are generally not for adjusting by the user, with the exception of cycle period.

Cycle period

This is the length of a single integration cycle. This is typcally set to 10 seconds and the observer uses the averaging flag in SCHED to set it to longer values. For non-mosaicing observations, an averaging of 3 is strongly recommended.

Hold increment

Expert mode only

The hold increment is the quantum of the smallest hold period to be applied. This should always be set to 512ms. The hold number is the number of hold increments required to make up the hold time. The hold time is the time at the start of the cycle for which there is no correlation.

Blank period

Expert mode only

This is the amount of time at the end of the integration cycle that no correlation is performed. It should always be set to 51ms.

LO backoff

Expert mode only

This is the time offset prior to the start of the next integration cycle that the LO phase rotators are set. This time allows them to settle before the next cycle starts. This value should always be set to 45ms.

SWcal

Expert mode only

This is the period of the noise diode switching. It should be 128ms.

Cycle start

Expert mode only

This is the time to start the next cycle. For certain applications, it may be appropriate for the cycle start to be set to a specific time, but most observers will be able to use the default.

Original: dmckay (20-Jan-1995)
Modified: nmckay (9-Oct-1995)