AIPS HELP file for DOUVCOMP in 31DEC18
As of Wed Sep 19 17:07:25 2018
Type: Adverb (Logical: <= 0 is false, > 0 is true)
Use: Instructs tape reading programs to write visibility data to disk
in AIPS compressed format. This format has one correlator value
(2 numbers) per floating word, magic value blanking, and a
single weight per visibility record. This may result in a
significant reduction in disk usage (up to a factor of 3). This
comes at a cost - the data must be compressed and uncompressed
as they are used which requires a multiply for every datum.
There is only one weight for all IFs and polarizations which
probably does not represent reality (even if all spectral
channels do have the same weight). Furthermore, the full
dynamic range of the numbers is 1 in 32768 which means that one
bad value can turn all the rest of the numbers into pure 0.
Null value: false (-1)