When CLASS was re-written in Fortran 90, it was decided to split
On-The-Fly spectra into one observation each2. This
eases spectra handling from the user side, but, of course,
multiplies the number of observations in a single file (typically by
a factor ). The increasing number of observations
(especially with the OTF acquisition schemes) and number of channels
of the back-ends produces larger and larger files. CLASS has thus
been revised with new file types and optimized with a faster
algorithm in order to ensure a maximal data rate from the software
side. We will expose here this new algorithm, and show that the
major limitation for
writing CLASS large files is currently on the hardware side.
Keywords: On-The-Fly, CLASS file format, data rate, user and system times.
Related documents: IRAM memo 2005-1: Improved OTF support