POS MV V4 User Guide
POS-GNSS Timing
Copyright © Applanix Corporation, 2009
H-3
Date
GNSS to
UTC Offset
(sec)
Date
TAI to UTC
Offset (sec)
Jan 1, 1996 11 Jan 1, 1996 30
Jul 1, 1997 12 Jul 1, 1997 31
Jan 1, 1999 13 Jan 1, 1999 32
Jan 1, 2006 14 Jan 1, 2006 33
Notes:
1. GNSS and TAI are ahead of UTC time, see
Figure 94.
Figure 94: GNSS. TAI and UTC Time
2. Consult the International Earth Rotation Service (IERS) web
pages for more quantitative information.
GNSS Timing Basics
One Pulse Per Second
The basis for all time and frequency functions is the One Pulse Per Second
(1PPS) signal supplied by the GNSS receiver. This signal is typically a short
logic pulse, one edge of which is adjusted by the receiver to be ‘on time’ with
respect to the one second epoch of UTC. In order to do this, the GNSS
receiver needs to know its position.
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