Meinberg GPS167PC - Manual (Page 8)

8
DCF77 Emulation
The GPS167PC satellite controlled clock generates TTL level time marks (active
HIGH) which are compatible with the time marks spread by the German long wave
transmitter DCF77. This long wave transmitter installed in Mainflingen near Frank-
furt/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, the clock generates
time marks representing its local time as configured by the user, including announce-
ment of changes in daylight saving and announcement of leap seconds. The coding
sheme is given below:
M Start of Minute (0)
R RF Transmission via secondary antenna (0)
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 (1)
P1, P2, P3 Even parity bits
Time marks start at the beginning of a 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. The DCF
emulation output is enabled immediately after power-up.