Technical Bulletin T-47M5 and 4530 Products 10-14-25
To provide owners and operators of the Tel-Instrument Electronics Corp. T-47/M5 and TS-4530A and T-4530i IFF Test Sets of details on an upcoming problem with the Trimble GPS module which may cause a GPS Roll Over that can affect the GPS stored date (year) acquired utilizing GPS as the time source.
Tel-Instrument engineering has identified an issue related to legacy GPS modules limiting the installed GPS module to properly roll over. Nearly all manufactured GPS receivers may experience the GPS week number rollover occurring every 1,024 weeks - about once every 19.7 years. Therefore, when 19.7 years has passed from the reference date in the systems, the clock time incorporated in GPS will be reset, causing as a result error in the date output of the Trimble GPS module resulting in an incorrect year being displayed. GPS position and time remain unaffected.
This will result in the test sets GPS Year will revert to the last known date and time of its original inception date, typically in 2006 for most manufacturers of GPS modules, including those used in the T-47/M5 and 4530 series of test sets.This issue is related to the actual GPS module and not related to the Test Sets operating system or programming. The certification of the Test Set is unaffected.
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