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authorGary E. Miller <gem@rellim.com>2019-05-27 15:03:32 -0700
committerGary E. Miller <gem@rellim.com>2019-05-27 15:03:32 -0700
commit6de94e9274c0ccd76927b5043fe159dc269b0aa1 (patch)
treed7af27aaeb03b5f633de8d6eb91b557d0e3af0f0 /www/gpsd-time-service-howto.adoc
parent4bc6a54b1f337674777181b80026e992b47ca4cd (diff)
parent0402eb81691882b4d693f9009f1f7369b205fa1d (diff)
downloadgpsd-6de94e9274c0ccd76927b5043fe159dc269b0aa1.tar.gz
Merge branch 'master' of ssh://git.sv.gnu.org/srv/git/gpsd
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@@ -137,12 +137,13 @@ second and the following subframe broadcast.
GPS date and time are subject to a rollover problem in the 10-bit week
number counter, which will re-zero every 1024 weeks (roughly every 19.6
-years). The last rollover (and the first since GPS went live in 1980)
-was in Aug-1999; the next will fall in Apr-2019. The new "CNAV" data
+years). The first rollover since GPS went live in 1980 was in Aug-1999,
+followed by Apr-2019, the next will be in Nov-2038 (the 32-bit and POSIX
+issues will probably be more important by then). The new "CNAV" data
format extends the week number to 13 bits, with the first rollover
occurring in Jan-2137, but this is only used with some newly added GPS
signals, and is unlikely to be usable in most consumer-grade receivers
-prior to the 2019 rollover.
+currently.
For accurate time reporting, therefore, a GPS requires a supplemental
time references sufficient to identify the current rollover period,