Decoding the particular DCF-77 Radio stations Time Sign


The DCF-77 radio stations time transmitting is made use of by several NTP server and also PC pcs to offer accurate synchronisation of energy critical software. This write-up describes how a DCF-77 moment signal will be decoded simply by NTP server and pcs to provide an accurate timing guide.

The DCF-77 Moment Transmitter.

The DCF-77 moment signal can be a long-wave radio stations time sign broadcast coming from Mainflingen, around Frankfurt, Philippines. The radio stations signal will be maintained simply by T-Systems, any sub-division regarding Deuche Telephony, and has been doing operation given that 1959. The DCF-77 sign is created from really accurate atomic clocks located on the German Countrywide Physics Clinical. When decoded, it gives you a very accurate timing guide for clocks and also computer timing products.

DCF-77 Moment Code.

Moment and time information will be transmitted continually, repeated each minute. The info is transmitted as a possible amplitude modulated, pulse-width coded info signal. Each info bit will be transmitted together pulse every second. The info transmitted contains the existing time and also date, step second signal, daylight conserving time signal, transmitter identifier and also parity parts.

The duration of each and every transmitted heart beat is decoded as follows: a next mark using a duration regarding 100 milliseconds will be decoded being a binary no; a next mark using a duration regarding 200 milliseconds will be decoded being a binary a single.

Transmitted Info.

Time and also date details is introduced in BCD (Binary Coded Decimal) format which is encoded as follows: bits 0-14 are usually unused, yet may offer future position information; bit 15 indicates usage of backup transmitter; tad 16 (A3), suggests the headline of sunlight saving modify; bit 18 (Z1), indicates sunlight saving is at use (CEST); tad 18 (Z2), suggests standard moment (CET); tad 19 (A2), announces any leap next; bit 20, indicates start of energy information; parts 21-27, BCD encoded moments; bit twenty eight (P1), parity tad covers parts 21-27; parts 29-34, BDC encoded hrs; bit thirty five (P2), parity tad covers parts 29-34; parts 36-41, BCD encoded evening of calendar month; bits 42-44, BCD encoded evening of few days; bits 45-49, BCD encoded month with the year; parts 50-57, BCD encoded yr; bit 58 (P3), parity tad covers parts 36-57.

The DCF-77 info bits 1-14 are often unused simply by any decoding algorithm and may even provide position information inside future broadcasts. Enough time zone parts Z1 and also Z2 reveal current sunlight saving moment status. When CET time will be broadcast, Z1 will be zero and also Z2 will be one, regarding CEST moment, Z1 will be one and also Z2 will be zero. The particular daylight conserving change headline bit, A3, indicates a great imminent modify to or perhaps from CET. The step second headline bit suggests the upcoming insertion of your leap next. The a few parity parts P1-P3 go with the earlier information to a even variety of ones (also parity).