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CLIC\SOLVE RF_PASSBAND [da] [dp] [/PLOT] [/SPECTRUM] [/RESET]
CLIC\SOLVE RF_PASSBAND [/IGNORE a1 a2 ...]
Solve for passband calibration curves, by fitting it to the amplitudes
and phases. The current index should contain calibration observations of
strong continuum sources (RF passband calibrator). The behaviour of this
command depends on the current mode of RF passband calibration (Frequen-
cy, Channel -- deprecated, or Spectrum). A baseband should have been se-
lected beforehand (see SET BBAND).
- For frequency-dependent RF passabnd calibration (SET RF_PASSBAND
FREQUENCY, recommended): the resolution is normally done using all
the spectral subbands plotted together, as a function of intermedi-
ate frequency. It should be done separately for each baseband and
sideband (if applicable). A single frequency-dependent polynomial is
fitted, a high degree might be necessary for the phase, if band
edges are used (up to 50 is feasible).
- For channel dependent RF passband calibration (SET RF_PASSBAND CHAN-
(i) For continuum, the data itself is directly stored as calibration
values (this gives a channel-dependent passband curve). In addition
a polynomial is fitted and optionally plotted (this gives a frequen-
cy-dependent passband curve).
(ii) For spectral subbands, polynomials are fitted and optionally
plotted, as a channel-dependent passband curve.
The degrees for polynomials are 'da' for amplitude, 'dp' for phase (de-
faults 0 and 1). Command STORE should be used next to store the fitted
function in the header of source observations. Both channel dependent
and frequency dependent curves can be stored; Use command SET RF_PASS-
BAND FREQUENCY|CHANNEL to apply one or the other.
Option /SPECTRUM supersedes any polynomial given and does use the data
points plotted to derive a bandpass solution. It will factorize the
gains per antenna if SET RF ANTENNA is selected. The bandpass solution
will then be computed by linear interpolation of these data points.
Option /PLOT will plot the polynomial fits over the data. Option /RESET
will reset polynoms in memory.
Option /IGNORE works only in ANTENNA mode. Antennas selected after op-
tion will be ignored in the factorization. This is useful for basebands
of the narrow-correlator when more than 6 antennas were used (with