The Network Time Protocol (NTP) was developed to provide a way of synchronising Internet clients to an accurate network time reference. NTP allows the time on client computers to be set to within a fraction of the correct time. The NTP protocol is a suite of programs designed specifically for time synchronisation purposes. The application source code is freely downloadable from the NTP website. Originally developed for the Linux operating system, NTP has since been ported to Microsoft Windows platforms. By interfacing an accurate reference clock to the NTP software distribution, you can provide a stratum 1 NTP server.
This article describes how to utilise a low-cost GPS receiver in combination with the NTP software distribution to provide an accurate stratum 1 NTP server timing reference. The NTP source code can be obtained from the NTP website and must be compiled on the local machine. The downloadable NTP tar file extracts to a directory where scripts are available to make compilation and configuration very straight-forward.
Many Linux distributions provide pre-installed versions of the software. To set up and install a stratum 1 time server a stable external timing reference is required. The NTP software provides a large number of reference clock drivers that can be utilised to interface with a range of hardware timing references. Dedicated hardware timing devices can be prohibitively expensive. However, the popularity of GPS navigation devices has reduced the cost of GPS technology.
Low-cost GPS receivers are now readily available from around $100. Many GPS receivers have a RS232 serial communications port, which can easily be connected to a PC. Most GPS receivers utilise the NMEA communications protocol which provides time and location information each second.
The timing information can be utilised by the NTP software as an accurate timing reference to provide a stratum 1 NTP server. The NTP software needs to be compiled with the NMEA reference clock driver to interface with the GPS receiver. Once compiled the application must be configured to utilise the correct serial port.
When correctly installed and configured, the NTP application will provide your network with an accurate, stable timing reference. A NTP server can be utilised to synchronise time on most computer operating systems and network infrastructure. Any network device that has an integrated NTP client can be configured to synchronise time with the NTP server. Generally, clients only need the IP address of the NTP server for synchronisation.
With a NTP server, you can synchronise almost any device on your network.
D. Evans is an experienced technical author to the computer time synchronisation and telecommunications industries. David provides a freelance technical authoring resource to many computer timing solutions providers. Click here for more detailed information about NTP servers.
