Reading raw HDS scan files

In the first implementation of optional raw data output in CONSTRICTOR, NPOI raw data of a scan was written into a single HDS formatted file. However, long scans (e.g. scans for atmospheric studies exceed 30 minutes) and the advent of the 6-way fringe engine made the current logic necessary, which is as follows. Scans will be divided into sub-scans, which have an additional extension after the scan number, identifiying the sequence number. Sub-scan files can still be read individually, but the standard procedure is to read and concatenate at least the time stamps and delay line metrology data from all sub-scans, and then to read the fringe data individually.


Procedure to read raw time and delay data from one or more sub-scan files specified by file_spec. Example: get_rawdata,'2001-10-25.raw.013'. Note that one does not include the sub-scan extension, as the procedure itself checks how many sub-scan files are present on disk. The data from all files found is read and concatenated. If there is only one sub-scan file, it will be left open. If no file is specified, it is assumed that a file is open, in which case the time and delay data of just this file will be read. The file will be left open.
Read the bin count data for the specified spectrometer. A raw HDS file must be open. The spectrometer number, i.e. the output beam, is stored in a common block for shared reference.
This standard procedure to read any kind of NPOI standard data files can be used to read a single raw file if the full filename is specified. All spectrometers will be read, and therefore the cautionary notes as to the spectrometer index in bincounts apply. The file will be left open.