9
DCF77 emulation
The GPS163xHS satellite controlled clock generates time marks which are compati-
ble with the time marks spread by the German long wave transmitter DCF77. If
configured in GPSMON32, these time marks are available as pulse outputs. In
addition, an AM-modulated carrier frequency of 77.5kHz is available via a BNC-
connector in the front panel. This signal can be used as a replacement for a DCF77-
antenna.
The long wave transmitter installed in Mainflingen near Frankfurt/Germany transmits
the reference time of the Federal Republic of Germany: time of day, date of month and
day of week in BCD coded second pulses. Once every minute the complete time
information is transmitted. However, GPS163xHS generates time marks representing its
local time as configured by the user, including announcement of changes in daylight
saving and announcement of leap seconds. The coding sheme is given below:
M
Start of Minute (0.1 s)
R
RF Transmission via secondary antenna
A1
Announcement of a change in daylight saving
Z1, Z2
Time zone identification
Z1, Z2 = 0, 1:
Daylight saving disabled
Z1, Z2 = 1, 0:
Daylight saving enabled
A2
Announcement of a leap second
S
Start of time code information
P1, P2, P3
Even parity bits
0
10
20
30
40
50
R
M
1
4
2
1
20
10
8
4
2
1
P
2
2
0
1
0
8
4
2
1
2
4
8
10
1
2
4
8
10
2
0
4
0
8
0
P
3
A1
Z1
Z2
A2
S
1
2
4
8
1
0
2
0
4
0
P
1
Minute
(reserved)
Hour
Day of Month
Day of Week
Year of the Century
Month of Year
Time marks start at the beginning of new second. If a binary "0" is to be transmitted,
the length of the corresponding time mark is 100 msec, if a binary "1" is transmitted,
the time mark has a length of 200 msec. The information on the current date and time
as well as some parity and status bits can be decoded from the time marks of the 15th
up to the 58th second every minute. The absence of any time mark at the 59th second
of a minute signals that a new minute will begin with the next time mark.
