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Signal Information

The 60 kHz AM signal is transmitted with a signal level of more than 10mV/m at 100km. The time information
is BCD coded within an 'One Minute Time Frame'. The carrier amplitude is switched off at the beginning 
of each second. Reducing the amplitude for 100 ms means binary zero, reducing it for 200 ms means binary one.
The transmitted data includes 5 bits for parity check. But the amplitude for the parity check bits is reduced for 200 ms
in case of a binary zero and for 300 ms in case of a binary one. At the beginning of the next time frame the amplitude 
is reduced for a duration of 500 ms.
Picture of the signal

- 100 ms = Binary '0'
- 200 ms = Binary '1' or Parity - Binary '0'
- 300 ms = Parity - Binary '1'
- 500 ms = minute marker
 
 
 
 

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BCD Time Code

Bit  Meaning  Bit  Meaning 
1  minute marker - switch over to the next time frame  53  Minute identifier (every time '0') 
2..17  carry *(DUT) information - not used  54  Set to '1' during the last hour before *BST change 
18..25  Year 55  Paritybit 'Year' 
26..30  Month 56  Paritybit 'Day+Month' 
31..36  Day of month 57  Paritybit 'Day of week' 
37..39  Day of week 58  Paritybit 'Hour+Month' 
40..45  Hour 59  *BST (=1) 
46..52  Minute 60  Minute identifier (every time '0') 

 

*DUT  = difference between atomic and astronomical time 
*BST  = British Summer Time 
Green - Original time information (BCD code)
Red  - Parity bit in connection with data bits (year, .., .., ..) provides an odd number of 1s


 
 
 

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BCD Code Example

Year  Month 
Second  18  19  20  21  22  23  24  25  26  27  28  29  30 
received Frame(ms)  100  100  100  100  100  200  100  200  100  100  200  200  200 
Bit Value  0  0  0  0  0  1 0  1 0  0  1 1 1
Information  2005  July 

Explanation :
Year = 0*80 + 0*40 + 0*20 + 0*10 + 0*8 + 1*4 + 0*2 + 1*1 = 5 + 2000 = 2005
Month = 0*10 + 0*8 + 1*4 + 1*2 + 1*1 = 7 = July
 
 
 
 
 

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