MONITOR

##
MONITOR

            CLIC\MONITOR delta_time

        This command is used to prepare the atmospheric phase  correction  based
        on  the  total  power  monitor (normally done at 1.3 mm). It process all
        scans in the current index and performs two operations.

        First, it processes the calibration scans to compute the correction fac-
        tors. i.e. the change of path length for a given change in emission tem-
        perature of the atmosphere at the atmospheric monitor frequency (normal-
        ly  1.3  mm,  i.e.  using Receiver 2 data). These correction factors are
        then written in subsequent scans, until a new calibration is found.

        Second, the scans in the current index are grouped in intervals of maxi-
        mum duration `delta_time' (in seconds); source changes will also be used
        to separate intervals. In each interval a straight line is fitted in the
        variation  of atmospheric emission as a function of time; this line will
        be the reference value for the atmospheric correction, i.e. the  correc-
        tion at time t is proportional to the difference between the atmospheric
        emission at time t and the reference at time t. This scheme is  used  to
        avoid  contaminating the correction with total power drifts of non-atmo-
        spheric origin (changes in receiver  noise  and  gain,  and  changes  in
        ground noise).

        MONITOR 0 will use for each scan the average of the atmospheric emission
        as the reference value. This will cause the correction to average to ze-
        ro  in one scan: the average phase is not changed, only the coherence is
        restored leading to an improved amplitude (this is what is done  in  the
        correlator  at the Plateau de Bure to compute the scan-averaged spectral
        and continuum quantities).