X
X
L
L
D
D
C
C
M
M
A
A
N
N
.
.
d
d
o
o
c
c
3
3
-
-
2
2
9
9
R
R
E
E
V
V
E
E
assuming the entry time was 2:00 a.m.. The sequence upon exit from DST is:
01:59:58
01:59:59
01:00:00
01:00:01
assuming the exit time was 2:00 a.m..
If the DST function is enabled or disabled when DST is already in effect, the display will take several
seconds to respond. Each time zone transitions into and out of Daylight Saving Time independently.
This means that if the current time zone just entered DST and the time zone offset is then changed by
means of keypad Function 01 to a time zone in which the local time of the transition has not yet
occurred, the standard time for that zone will be displayed. If the original time zone setting is restored,
its time will remain in DST.
3-167 reserved
3-168 KEYPAD FUNCTION 68 - YEAR ENTRY (GPS EPOCH MANAGEMENT)
The GPS week number sent from the satellites has only 10 bits of precision, so that 1024 weeks from
January 6, 1980 (GPS week 0) it rolls back to 0. To correctly calculate calendar dates after this roll
point, firmware keeps track of the current year so that it can construct an absolute, non-rolling week
number since January 6, 1980.
The firmware has the current year embedded in code, and will properly handle dates through the year
2015. In addition, as the clock advances to each new year, the current year is updated and used in
future calendar calculations, thus calculations beyond 2015 are handled properly. No user intervention
is required as long as the current year saved in non-volatile memory is intact, and so long as the clock
runs locked to GPS at least once each 5 years to allow the year to be updated. If after 2015, the
current year saved in non-volatile memory is lost, or the clock is not locked to GPS within 5 years of
the last year saved in non-volatile memory, then Function 68 can be used to manually enter the current
year. Years prior to 1996 are not accepted, and entering a future year may cause incorrect calendar
date calculations.
To request the current year setting via Keypad Function 68, perform the following steps.
Press "FUNC/ENTR" "6" "8" and the display will show:
Set current year
\
_1996
The year displayed will be the year saved in non-volatile memory used in the calendar calculations. To
change it, enter the current year, then press "FUNC/ENTR". The display will prompt with:
Save year?
No
To save, use the up arrow key to change "No" to "Yes", then press "FUNC/ENTR".
Summary of Contents for 151-600
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