l2a - LORAL archive to ascii file

Documentation for the MAXIMA archive extraction program:

Usage: l2a infile [outfile]
Files: asciiout.par (or other file specifying output parameters).
Input information: parameter file name, start time, stop time.

l2a extracts data from the input file and writes it to the output file. If the output file is not specified, the name is taken to be the input file name up to the first period/dot, with the extension ".dat". It begins by reading the input file header to find the descriptions of the stored parameters. It then makes sure that there is a valid frame counter.

Next it asks for the name of the file describing the needed output parameters, and reads that file. The file specifies the size of maximum output record in bytes, the number of channels, and then lists the parameters associated with each channel, and what format it should be written in. The header record (which records the start sample number (counted as number of sample/frame times the frame counter), the number of samples output, and the universal time at start of the file in digital hours) will be padded with null characters to the maximum record size. The output records are composed of a line with the listed channels, a status number (set to 0 for good data), and a newline to terminate the record.

Unlike l2b, l2a implements the parameter mask (in some of its output formats). For the "u" format and all of the non-decimal formats, the parameter is masked as indicated in the parameter descriptions. The current formats are,

i - this interprets the input data as an unsigned 2 byte integer in the range 0 to 65535. It shifts the center of the range to 0 by subtracting 32768, and outputs it as a signed integer in the range -32768 to 32767. This is appropriate for data collected by the DAS A/D converter.
d - this interprets the input data as a signed 2 byte integer, and outputs it as a signed integer. This is appropriate for the ACS data that comes through the SIM.
u - this interprets the input data as an unsigned 2 byte integer and prints it out as an unsigned integer. This is the first of four ways appropriate for viewing digital words.
x - this interprets the input data as an unsigned 2 byte integer and prints it out as an unsigned hexidecimal integer. This is appropriate for viewing digital words.
o - this interprets the input data as an unsigned 2 byte integer and prints it out as an unsigned octal integer. This is appropriate for viewing digital words.
b - this interprets the input data as an unsigned 2 byte integer and prints it out as an unsigned binary integer. This is effectively displaying the raw bits as they were received in the telemetry stream.

Finally, l2a asks for the start time and stop time for the extracted data segment. The default day is that of the start time of the file, and the user can give one of three formats:

days:hours:minutes:seconds
hours:minutes:seconds
digital hours

Days, hours, and minutes are integers. Digital hours and seconds are real numbers.

At this point l2a finds the beginning of the data segment, displays a note that it has found the beginning and extracts data. If there are discontinuties in the frame counter, diagnostic messages are printed. When the frame counter is bad, or if there are missing frames, the data is recorded as all 0's and the status number is set to 2.

Check the source code directory for documentation on the source code. This directory is currently: //garbo.berkeley.edu/lange/users/wilbanks/max/loral/source

author: Thor Wilbanks

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