Set the power measurement and zero-calibration interval of the noise cal system.

Arguments:

Time power_dt

The interval between noise-power measurments.

Time zero_dt

The interval between noise-power zero calibrations.

Example:

The following example sets the interval between noise-power measurements to 1 minute, and the interval between zero-calibrations of the measurement system to 10 minutes.

 noise_cal_interval 0:01, 0:10

Context:

Primary calibration of the CBI receivers is achieved by periodically observing calibration sources. Between primary calibrations, changes in receiver gains are deduced by injecting the output of a noise source into the receivers. Since this noise source can itself vary, a power meter is used to monitor its output. By default the power meter is read once per minute, and it's zero-offset is recalibrated every 10 minutes.

Note that with the current power meter, while the zero-calibration process only takes between 15 seconds and a minute, it apparently takes much longer than that for the power meter measurements to settle down.

Also note that although the arguments to the above function allow one to specify subsecond intervals, a minimum interval of 1 minute is enforced, and other values are rounded to the nearest minute. If the interval for zero calibrations is less than or equal to the power-measurement interval, sequential zero calibrations will occur without any intervening power measurements.