These pages describe three programs used with LORAL system archives:
The LORAL system archives the data in binary files. These files have a format made up of a main header, a set of parameter description blocks, and data stored in data blocks with individual headers. Given the basic format structure, it is possible to decode the file to determine when it was acquired, and what data was archived.
The main header information includes the number of parameters, and the size of each parameter description block. Each parameter description block defines that parameter, including its name, where it can be found in the the data blocks, and so on.
Each data block has a header that includes a time stamp that corresponds to the time at which the computer decoded that telemetry data. Typically, there are a small integer number of frames stored in a single data block. The data is grouped together by parameter, rather than by frame.
All three of the "extraction" programs descibed here can read a file and determine the parameters archived, whether there is a 2 or 4 byte frame counter, and when the file started and stopped. Beyond that they differ in that:
Both l2a and l2b select the parameters to extract by reading a short file that lists the default/fixed record size, the number of parameters to extract, and the list of parameters including the desired format of output. The first line of the file and the end of the file (after the list of parameters) is ignored, so that these files can be thoroughly commented/identified. Examples should be in the original binary directory, although users will probably want to keep their working copy(ies) in the directory(ies) with the archives being investigated.
author Thor Wilbanks
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