NeoClock
page 10
7. OPERATION
NeoClock picks up long wave signals broadcasting time reference signals.
It is available with two different antenna systems. One picks up the DCF77
signal and the other picks up the France Inter signal.
The DCF77 signal comes from a long wave transmitter that broadcasts time
signals on 77.5 kHz. T
he France Inter signal comes from a long wave transmitter that broadcasts
time signals on 162 kHz.
Both transmitters use a very simple protocol: every minute, the full date and
time are transmitted in 59 bits at a frequency of 1 bit per second. The 60
th
bit
is not emitted and is thus used as a marker for the beginning of the next time
sequence.
In order to achieve the best reception possible, NeoClock features an
original system with two antennas. A sophisticated demodulator system
sends its pulses to the microprocessor of NeoClock for sampling, decoding
and saving.
In order to guarantee the safety of the data, the NeoClock processor
discards any irrelevant data such as hour 27, day 32, month 18, … (these
values can actually appear in the case of electromagnetic disturbances, for
instance). The processor also checks three parity bits for each data string
and the exact timing between all pulses.
If no errors were detected during the checking process, the whole data
sequence is saved to be compared with the following sequence. If no error
is detected at this point, the autonomous quartz clock of NeoClock is
synchronised with the atomic clock as soon as the synchronisation signal is
identified (it corresponds to the zero-second shift).
Содержание NeoClock
Страница 1: ...NEOL NeoClock User s guide Radio controlled clock NEOL S A Version 06 2001 E N G L I S H ...
Страница 2: ......
Страница 26: ...NeoClock page 22 NOTES ...
Страница 28: ...NeoClock page 24 ...