system_time [ATSC Semantics]

system_time, which also might be called ATSC Seconds, is a 32-bit field that gives the number of GPS seconds that have elapsed since January 6, 1980. system_time is transmitted in the System Time table and is referenced as the start time for events in Event Information table listings.

While system_time is a count of GPS seconds, the number of seconds is directly relatable to Universal Coordinated Time (UTC) and can be converted to GPS time by adding the GPS_UTC_offset value which also transmitted in the System Time table.