QSSP_point.h File Reference
Defines a standard sample point.
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#include <QSD/QSD_timetone.h>
Detailed Description
Defines a standard sample point.
- Author:
- JJRussell - russell@slac.stanford.edu
CVS $Id: QSSP_point.h,v 1.2 2011/03/29 00:14:57 russell Exp $
A sample point captures the conditions at either the beginning or ending of a sample. While, as time goes by, there may be different versions of this structure, this basic function remains the sam.e
- This structure is used to uniquely identify an event in both time and sequence. As such, it contains enough information to calculate the absolute time of the event. To do this one needs the GEM clock frequency which can be got in an assumption free fashion by capturing the GEM clock value on two successive timetone/1PPS hacks. The difference in the GPS timetone messages gives one the elapsed seconds and the difference in the GEM clock register values gives how many clock ticks have passed during this period.
- The event sequence number is merely the GEM sequence number extended by watching how many times this sequence counter overflows. (Overflow is defined as going from a given value to a lower value.) While this is an easy enough value to compute, the writer is encouraged to use the value from EDS_fwIxb. This will ensure agreement when readers examine data from different statistics blocks.
- Note:
- This structure exists so that it may passed to a convenience routine (likley within THS) for easy filling.
