Andreas Sikstrom writes:
>I'm searching for information about the radio transmitter DC-77 in Germany
>which sends out time info.

>Email reply, please!


>// Andreas

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Time info transmitter in GERMANY:

Station Name :                  DCF 77.5kHz
Frequency :                     77.5KHz
Transmitting Power :            50kW
Radio Station :                 Mainflingen
Geograpical Coordinates :       50°01'N,09°00'E
Time of Transmission :          permanent

Modulation : 
The carrier amplitude is reduced to 25% at the beginning of each second
for 100ms (binary zero) or 200ms (binary one) duration excepting the 
59th second.

Time Code Format:
It consists of 1 minute time frames. No modulation at the beginning of
the 59th second serves to recognize 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
the 58th second of the time frame, including the start bit S (200ms) and
the parity bits P1, P2 and P3. Further there are 4 additional bits R
(transmission by reserve antenna), A (announcement of change-over to the
summer time), Z1 (during the summer time 200ms, otherwise 100ms) and Z2
(during standard time 200ms, otherwise 100ms) transmitted between the 15th
second and the 18th second of the time frame. More details are shown in
the following table:

time frame of 1 minute:

second          description     
------------------------------------------------
0...14          coding when required
15              R  = reserve antenna
16              A  = announcement to summer time
17              Z1 = summer time
18              Z2 = standard time
19              reserved
20              S  = start bit
21              1  minutes
22              2  minutes
23              4  minutes
24              8  minutes
25              10 minutes
26              20 minutes
27              40 minutes
28              P1 parity
29              1  hours
30              2  hours
31              4  hours
32              8  hours
33              10 hours
34              20 hours
35              P2 parity
36              1  calendar day
37              2  calendar day
38              4  calendar day
39              8  calendar day
40              10 calendar day
41              20 calendar day
42              1  day of week
43              2  day of week
44              4  day of week
45              1  month
46              2  month
47              4  month
48              8  month
49              10 month
50              1  year
51              2  year
52              4  year
53              8  year
54              10 year
55              20 year
56              40 year
57              80 year
58              P3 parity
59              uncoded

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Time info transmitter in the USA:

Station Name :                  WWVB 60kHz
Frequency :                     60kHz
Transmitting Power :            10kW
Radio Station :                 Fort Collins
Geograpical Coordinates :       40°40'N,105°03'W
Time of Transmission :          permanent

--------------------------------------------------------------------------
Time info transmitter in GREAT BRITAIN:

Station Name :                  MSF 60kHz
Frequency :                     60kHz
Transmitting Power :            50kW
Radio Station :                 Teddington,Middlesex
Geograpical Coordinates :       52°22'N,01°11'W
Time of Transmission :          permanent, excepting
                                the first tuesday of
                                each month from 10.00h
                                to 14.00h

--------------------------------------------------------------------------
Time info transmitter in SWITZERLAND :

Station Name :                  HBG 75kHz
Frequency :                     75kHz
Transmitting Power :            20kW
Radio Station :                 Neuchatel
Geograpical Coordinates :       46°24'N,06°15'E
Time of Transmission :          permanent

--------------------------------------------------------------------------

If you are going to design your one receiver I recommend following IC:

U4221B-A from TELEFUNKEN electronic (TEMIC)

It's a bipolar integrated straight through receiver circuit in the
frequency range of 60..80kHz. The device is designed for radio controlled
clock application.

Features:

* low power consumption
* very high sensitivity
* high selectivity by quartz resonator
* stop function available
* only a few external components necessary
* digitized serial output signal
* package: SO16
* supply 2.4V ... 5.5V
* current consumtion max. 40uA (!) in stop mode 0.2 uA (!!!)
* field strenght output indicates input level < 5uV
* power on/off input to stop the receiver

To receive the DCF77.5kHz you need only following design:

        ferrite antenna L, tuned to 77.5kHz with C
        ======        
       +-[##]-+---------------*VCC            
       | L    |    -------- 
       +--||--+---| 1    16|--*VCC
       | C        |        |
       +----------| 2    15|--|GND
                  |        |
       GND|-------| 3    14|------<---- PON = Power On
            220nf |        |                  H=on,L=off
       GND|---||--| 4    13|------>---- TSO = Serial Out; 
             47nf |        |
       GND|---||--| 5    12|------>---- FSI = Field Strenght 
           77.5KHz|        |                  H=Input > 5uV
          +--|Q|--| 6    11|--|GND
          |       |        |
          | GND|--| 7    10|-nc
          |       |        |
          +-------| 8     9|--*VCC
                   --------
                   U4221B-A                   

It's easy, isn't it ? And it works very fine ...


-- 
  Ingolf Pohl                                 
  Kiel, Germany