SUBSCAN
Keywords: pako

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SUBSCAN

        SUBSCAN xOffset    yOffset
        SUBSCAN xStart     yStart     xEnd       yEnd
        SUBSCAN xAmplitude yAmplitude frequencyX frequencyY xCenter yCenter phiX phi

        NB: this is a protected command (needs privilege).

        Add to user-defined list of subscans and segments for observing mode "DIY";
        compare command DIY. The subscan command has the 3 main variants above,
        depending on the number of parameters:

        2 --> Track subscan with fixed offsets
        4 --> Linear OTF segment (subscan)
        8 --> Lissajous OTF segment (subscan), IMPORTANT: SEE NOTE BELOW

        Option /TYPE allows to enforce that the command is interpreted for one
        the 3 different types, independant of the number of parameters.

        Option /TUNE allows to specify that a Track subscan will be used to "tune"
        an instrument, e.g., NIKA.

        Real :: xOffset     ! x offset fixed-position TRACK subscan
        Real :: yOffset     ! y offset fixed-position TRACK subscan

        Real :: xStart      ! x offset start  of linear OTF  segment
        Real :: yStart      ! y offset start  of linear OTF  segment
        Real :: xEnd        ! x offset end    of linear OTF  segment
        Real :: yEnd        ! y offset end    of linear OTF  segment

        Real :: xAmplitude  ! x amplitude              Lissajous OTF segment
        Real :: yAmplitude  ! y amplitude              Lissajous OTF segment
        Real :: frequencyX  ! frequency    [Hz]  for x Lissajous OTF segment
        Real :: frequencyY  ! frequency    [Hz]  for y Lissajous OTF segment
        Real :: xCenter     ! x center                 Lissajous OTF segment
        Real :: yCenter     ! y center                 Lissajous OTF segment
        Real :: phiX        ! phase offset [rad] for x Lissajous OTF segment
        Real :: phiY        ! phase offset [rad] for y Lissajous OTF segment

        If an asterisk * appears in place of any parameter, the value will
        remain unchanged from the last valid SUBSCAN command.

        NOTES: pako will make its best effort to "guess" the values for
        unspecified parameters based on the values of its internal variables
        after the previous valid SUBSCAN command.
        Each time a SUBSCAN is accepted without error message, a subscan is
        added to the list; even if the command is only "SUBSCAN" by itself!
        Be careful that a parameter in the command line can refer to different
        variables depending on the type of the segment/subscan, e.g., the 1st
        parameter can refer to xOffset, xStart, or xAmplitude.
        These features should be used with special care, e.g., to experiment
        with the DIYLIST and SUBSCAN commands.
        It is recommended to collect all SUBSCAN commands in a paKo script and
        explicitly specify all parameters for each subscan!

        Before START of a DIY subscanlist, you can enter DIYLIST to review
        pako's I-DIY messages listing the subscan currently defined (this
        requires SET LEVEL 2 or lower), e.g.:
        PAKO> set level 2
        PAKO> diy
        I-DIY,  segments #: 1 to 3
        I-DIY,  1 track on at -400.0 -300.0 arcsec projection 10.0 s
        I-DIY,  2 onTheFly -300.0 -200.0 to 330.0 220.0 arcsec projection 66.0 s
        I-DIY,  3 track on at 440.0 330.0 arcsec projection 10.0 s

        IMPORTANT: LISSAJOUS OTF

        During a Lissajous OTF segment, the position offsets
        x and y as a function of time t are:

        x = xCenter + xAmplitude * SIN(2 Pi frequencyX t + phiX)
        y = yCenter + yAmplitude * SIN(2 Pi frequencyY t + phiY)

        SIN is the usual sine function, Pi is the number Pi.

        xAmplitude yAmplitude xCenter yCenter are in angle units ([arc sec])
        frequencyX frequencyY                 are in [Hz]
        phiX       phiY                       are in [rad]

        Note that the possible frequencies are very low,
        typically 0.01 to 0.15 Hz.

        At the start of a Lissajous subscan, paKo will insert a "ramp" along a
        straight line, i.e., a linear OTF segment, increasing the count of
        segments by 2.  This ramp up starts with speed 0 relative to the
        source and joins smoothly with the start position and velocity of the
        Lissajous segment.  The purpose is to avoid a sudden aceleration at
        the start of the Lissajous segment.  Command DIY lists this inserted
        OTF segment as well as the Lisssajous segment.  The inserted ramp up
        segment and the Lissajous segment become part of the same subscan.

        Lissajous curves with large amplitudes or frequencies can reach the
        antenna's speed and acceleration limits for tracking.  Lissajous
        curves can be executed only for elevations less than a maximum, which
        depends on the Lissajous parameters.  For information, this elevation
        condition is shown by pako. Even below the limits, during very fast
        Lissajous curves the tracking errors will be higher, several arc sec,
        than during most other observations.

        DO NOT TRY TO OBSERVE LISSAJOUS ABOVE THIS MAXIMUM ELEVATION.

Subsections

- SUBSCAN /CROFLAG
- SUBSCAN /RAMP
- SUBSCAN /SYSTEM
- SUBSCAN /TOTF
- SUBSCAN /TSUBSCAN
- SUBSCAN /TUNE
- SUBSCAN /TYPE