Time Synchronisation For Computer Networks

TimeTools provides a wide range of PC time synchronisation devices based on radio and GPS atomic clock technology that can ensure reliable accurate time on Microsoft Windows 7, 2008 R2, XP, VMware or Linux/Unix machines. We also provide dedicated network time servers that can ensure the correct time on a large number of network time clients.

By utilising GPS or radio external time references our timing products can synchronise a single PC or a complete network of devices.

GPS Time Synchronisation

The GPS system is a constellation of 24 orbiting satellites primarily intended for navigation and positioning. However, in order to provide precise positioning information, each satellite has a very precise atomic clock installed. These very precise clocks can be used by ground-based receivers to obtain accurate timing information.

By utilising a well-located GPS antenna, a timing receiver can provide a consistent supply of accurate time stamps to a host computer. The timing receiver can communicate accurate time to a host computer via a serial or USB interface. Driver software installed on the computer can then read time stamps from the receiver and very precisely adjust the operating systems time so that it coincides with the correct time.

NTP Time Server - TimeTools SC Series

GPS Time Synchronisation Appliance

 

The LC2750 GPS Time Server utilises GPS atomic clock technology for precise computer system time synchronisation.

More on LC2750 GPS Time Reference.

Computer Interfaces

RS232 serial interfaces are a preferred means of communicating timing information between references and PC’s. Serial interfaces consist of data transmission lines and control lines. The data transmission lines convey alpha-numeric characters between a device and host. The control lines indicate status information, such as ‘Clear To Send’ (CTS) and ‘Ready To Send’ (RTS).

The serial data transmission lines can be used to transfer actual character-based time and date information to a host PC. However, due to buffering of characters, the data lines alone cannot be used to convey accurate time. However, RS232 input control lines are connected to hardware interrupts and can be used to provide highly accurate event timing. These control lines can be used by a PC to obtain a precise time stamp. Thus, by using the data transmission lines in conjunction with the control lines, precise time stamps can be accumulated by a host computer.

USB interfaces can be used for timing but are essentially software based and have an inherent processing delay. This inevitably means that they are not as accurate as RS232 serial interfaces for timing purposes.

Network Time

By far the most widely used means of disseminating time around a computer network is the Network Time Protocol (NTP). NTP provides a means of transmitting accurate time stamps from a time server to time clients. Typically, a GPS synchronised NTP server maintains an accurate source of time for an entire network. Clients then periodically request time from the server in order to synchronise their internal real-time clock. Clients can typically sync their clocks to with a few milliseconds of the correct time.

TimeTools SR series of stratum 1 network time servers obtain very accurate time from external time references, such as GPS and LF radio. The devices utilise the supplied timing information to precisely synchronise a computers internal real-time clock.

NTP Server - TimeTools SR Series

SR Series NTP Server Appliance

 

SR Series GPS NTP Server can utilise GPS or LF radio references and sync many thousands of clients.

Digital Clocks

Many other network devices can utilise the NTP protocol, including CCTV systems, routers, telephone systems and digital clocks. TimeTools digital wall clocks can utilise the NTP protocol over a network to provide a synchronised time display. The clocks synchronise to a master clock NTP server so that multiple display all show the same correct time.