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Chapter 2. HISCALE Data File Descriptions and Overview

The HISCALE archive records (level 1) are generated from the Experimental Data Record (EDR) (level 0).  The contents of the HISCALE archive record are given in section 2.3 below, including the record header, RATE block (count rate), PHA (Pulse Height Analysis) block, and MFSA (M and F spectra accumulation) block.

Each record has a record header, and either one of the RATE block, PHA block, or MFSA block.  The RATE block archive file contains only the RATE records (record header + RATE block), and each RATE archive file contains one day of RATE records.  The name of the file is ULAyyddd.RAT where yy is the last two digits of the year, and ddd is the Julian date.  The PHA and MFSA records are put together in one file, ULAyyddd.PHA.  ULAyyddd.PHA also contains one day of MFSA and PHA records.

Full time resolution is maintained in the first processing step (level 0 to level 1).  The procedure called ARCGEN decommutates, decompresses and reformats the HISCALE date and writes RATE records, MSFA records, and PHA records to output files.  The RATE records then serve as input to a procedure LANAVG which forms time averages.  MAGMERGE, applied to AVG or RATE RECORDS, inserts the magnetic field, and computes and inserts the pitch angle information.  Finally, the AVG records, which are written with all data collapsed into the spin one position of the 10 spins reserved for repetitions, can be COMPRESSED (10:1) into more compact records.

Compatibility of data and record representations across different computer systems is accomplished with an I/O package called LANIO.  The archive files are generated at Fundamental Technologies on a VAX/VMS system.  However, since the HISCALE team is comprised of VAX/VMS and Unix users, special I/O routines, HSIO and HSTRANS, have been used to facilitate the conversion of HISCALE archive data from the VAX/VMS to the Unix system.  The diagram below shows the use of HSIO and HSTRANS.

The archive record created with HSIO consists of:
1. A record header of 8 bytes which contains the record size of the file and the number of bytes of data in the record.
2. The archive data, which is a combination of Rate, PHA, and MFSA records.
3. Padding to the record size, with zero bytes.

The record size of the file is the maximum record size passed to or returned from HSIO plus the size of the header (8 bytes). In the case of VMS systems, the file is a fixed-record-length file with this record size. On Unix systems the record structure is software imposed (hence the reference to pseudo-records). The format allows quick access to the data, but since all records are of the same form and size there are no hidden bytes in the file and utilities such as the VMS APPEND command can be used to concatenate files.

Next: Chapter 3

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Updated 5/12/09, T. Hunt-Ward