Daytime Protocol

Abstract: The invention discloses an embedded-type high-precision network time server system which is composed of a clock source switch-on module, a clock source decoding module, a microsecond time counting module, a time information register module, a network time server port module, a network time server module, a system storage module and a system remote access module. The embedded-type high-precision network time server system is capable of automatically choosing global position system signals, range instrument group (IRIG-B) codes or big dipper signals as system external time reference signals according to signal quality, and microsecond-level time is produced through constant temperature crystal oscillator in the interior of the embedded-type high-precision network time server system, system reference time source precision is improved, and at the same time network time protocol (NTP), simple network time protocol (SNTP) and daytime protocol (daytime) are provided for carrying out time calibration to other clients in the network. In addition, system network addresses can be further inquired reversely and set by the embedded-type high-precision network time server system through remote manners, and network management difficulties can be reduced. The embedded-type high-precision network time server system is capable of achieving network time timing service with o.1 millisecond-level error and making up defects that the traditional time server time reference signals are difficult to change, low in time precision and inconvenient to manage.

Abstract: Responding to an increased demand for reliable, accurate time on the Internet and Milnet, the U.S. Naval Observatory Time Service has established the network time servers, tick.usno.navy.mil and tock.usno.navy.mil. The system clocks of these HP9000/747i industrial work stations are synchronized to within a few tens of microseconds of USNO Master Clock 2 using VMEbus IRIG-B interfaces. Redundant time code is available from a VMEbus GPS receiver. UTC(USNO) is provided over the network via a number of protocols, including the Network Time Protocol (NTP) (DARPA Network Working Group Report RFC-1305), the Daytime Protocol (RFC-867), and the Time protocol (RFC-868). Access to USNO network time services is presently open and unrestricted. An overview of USNO time services and results of LAN and WAN time synchronization tests will be presented.