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SOLVE AMPLITUDE
CLIC\SOLVE AMPLITUDE [/PLOT] [/BREAK kind time [kind time ...]
[/POLYNOMIAL [degree]] [/WEIGHT]
*** THIS HELP HAS NOT BEEN UPDATED FOR THE NGRX ***
This command fits a mathematical function into the measured amplitude of
the sources in the current index (presumably calibrators). This data must
have been selected and plotted in axes : SET X TIME and SET Y AMPLITUDE
for the baselines and bands of interest, specified by the corresponding
SET commands. The calibration function is kept in memory. Command STORE
AMPLITUDE should be used next to store this function in the header of
source observations, after a change in the index to select the appropriate
scans.
SOLVE AMPLITUDE internally and temporarily resets SET AMPLITUDE to SCALED.
In antenna mode (selected by SET AMPLITUDE ANTENNA), the averaged phase
and amplitude closures are computed, as well as their standard deviations.
The phase closures should be close to zero, while the amplitude closures
should be close to 100%. Strong deviations of amplitude closures from 100%
are an indication of amplitude loss on long baselines, due to phase decor-
relation during the time averaging. The fit then shows strong systematic
errors; if this occurs, baseline based calibration of the amplitudes might
be preferred.
Option /PLOT will plot the fitted curve over the data.
Fitted curves may be of two kinds:
- Cubic splines (the default). By default knots are regularly spaced
with an interval between knots set by the SET STEP command. Addition-
al knots may be introduced with the option "/BREAK kind time [kind
time ...]" which introduces a break at abscissa 'time'; 'kind' is an
integer in the range 0-3; 0 means that a discontinuity will be
present, 1 that the first derivative will be discontinuous, and so on.
Several breaks may be introduced. The program will detect an error if
too many breaks are introduced, compared to the density of data
points.
- Polynomial curves may be used instead. For this the option is: /POLY-
NOMIAL [degree] indicating the degree of the polynomial (default 0).
Normally the data points are all assigned the same weight for the fit.
With option /WEIGHT, the data points are weighted according to their er-
rors.
Gildas manager
2011-04-01