Logo PTB
View of the Mainflingen long-wave radio station for transmission of the DCF77 signal: transmitter building (in the back), antenna building (yellow bricks) and antenna masts.

Time dissemination via the Internet

Coordinated Universal Time as realized at PTB, UTC(PTB), is also made available by PTB via the Internet. From two publicly accessible servers, UTC(PTB) can be enquired under the addresses ptbtime1.ptb.de or ptbtime2.ptb.de. Independent of GPS, the server clocks are directly synchronized on two different ways via optical fibres by the atomic clocks of PTB. For control, each server receives UTC(PTB) additionally on a third way from a DCF77 radio-controlled clock. For dissemination of the time, the servers use the “Network Time Protocol“ (NTP). This protocol allows computers to be synchronized in local networks and in world-wide networks, provided they are equipped with suitable software which support NTP. Such software is available for all current operating systems. A list of such programs as well as other information regarding the time service of PTB in the Internet can be found on the WWW pages of the “Server systems” Working Group (Q.42) under Opens internal link in current windowtime synchronization of computers.