t4225b ATMEL Corporation, t4225b Datasheet - Page 12

• Manufacturer Part Number: t4225b
• Description: Low-cost Time-code Receiver
• Manufacturer: ATMEL Corporation

Information on the German Transmitter
Station: DCF 77,
Frequency 77.5 kHz,
Transmitting power 50 kW
Modulation
The carrier amplitude is reduced to 25% at the beginning
of each second for a period of 100 ms (binary zero) or
200 ms (binary one), except the 59th second.
Time-Code Format: (based on
Information of Deutsche Bundespost)
The time-code format consists of 1-minute time frames.
There is no modulation at the beginning of the 59th
T4225B
seconds
12 (16)
Example:19.35 h
20
0
s
21
coding
when
required
5
1
Start Bit
22
10
2
23
15
4
24
minutes
20
8
minutes
Time frame 1 minute
25
( index count 1 second )
25
10
26
Figure 23.
30
20
hours
27
Location: Mainflingen/Germany,
Geographical coordinates: 50 __ 0.1’N, 09 __ 00’E
Time of transmission: permanent
second to indicate the switch over to the next 1-minute
time frame. A time frame contains BCD-coded
information of minutes, hours, calendar day, day of the
week, month and year between the 20th second and 58th
second of the time frame, including the start bit S (200
ms) and parity bits P1, P2 and P3. Furthermore, there are
5 additional bits R (transmission by reserve antenna), A1
(announcement of change-over to summer time), Z1
(during summer time 200 ms, otherwise 100 ms), Z2
(during standard time 200 ms, otherwise 100 ms) and A2
(announcement of leap second) transmitted between the
15th second and 19th second of the time frame.
40
35
28
calendar
day
P1
40
29
day
of
the
week
1
Parity Bit P1
45
30
month
2
31
50
year
4
hours
32
55
8
Parity Bit P2
33
0
Rev. A3, 03-Dec-98
10
34
Time frame
5
20
35
93 7527
10
P2