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LISSAJOUS
LISSAJOUS xAmplitude yAmplitude
/CENTER xCenter yCenter
/FREQUENCY frequencyX frequencyY
/PHASES phiX phiY
/TOTF tOtf
/SYSTEM system
additionally for NIKA:
/FOCUS f1 f2 [... f18] [direction]
/POINTING [yes|no]
/TUNE xOffsetT yOffsetT
/TTUNE tTune
Specify an On-The-Fly (OTF) map with a Lissajous curve in 1 subscan.
LISSAJOUS is at this time (2014-11-10) supported only for GISMO and NIKA
Real :: xAmplitude ! amplitude for x-offsets
Real :: yAmplitude ! amplitude for y-offsets
Real :: xCenter ! center x-offset
Real :: yCenter ! center y-offset
Real :: frequencyX ! frequency [Hz] for x
Real :: frequencyY ! frequency [Hz] for y
Real :: phiX ! phase offset [rad] for x
Real :: phiY ! phase offset [rad] for y
Real :: tOtf ! time [s]
Character :: systemName ! name of system, one of:
! PROJECTION
! TRUEHORIZON
Real :: f1 f2 [... f18] ! focus offset [mm] during each Lissajous cur
Character :: direction ! direction of focus offsets, one of:
! X
! Y
! Z
Real :: xOffsetT ! x-offset for tune subscan
Real :: yOffsetT ! y-offset for tune subscan
Real :: tTune ! time [s] for tune subscan
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 acceleration at
the start of the Lissajous 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
Gildas manager
2023-06-01