[daip] problem with POSSM
Leonia Kogan
lkogan at aoc.nrao.edu
Tue Aug 27 10:19:56 EDT 2002
Denise,
The CQ table was invented to make a correction for possible reduction
of the amplitude as a result of preaveraging at the correlator.
If the fringe rate is big then the amplitude of the signal can be
partially self averaged during the vector averaging at the correlator.
Lets consider that time averaging at the correlator is 1sec and
fringe rate is 0.1 Hz then the averaging at the correlator will reduce the
amplitude at the (pi*0.1*1 / sin(pi*0.1*1) = 1.0166 times (if the box weighting
is used at the correlator). Having known the fringe rate (after FRING) we can
make the correction of the amplitude reduction,
if we know the parameters of the correlator averaging.
-------------------------------------------------------
These parameters are stored at the CQ table: time averaging, weighting function,
and.....
In real life (at least for VLBA) the residual fringe rate is too small to have
a sence making this correction.
I have compared your CQ table with a correct one and found huge numbers at
the column FILTER and zeros!!! at two lines of the TIME_AVG column.
The last one is an obvious error.
The table is created under control of the parameter DELCOR at the FITLD.
S drujeskim privetom
Leonia
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