A GPS time server is a hardware appliance that provides an accurate time reference to a network of computers. By utilizing the Network Time Protocol (NTP), the device ensures that each computer on a network is synchronized to the correct time. Very precise timing information is obtained from the Global Positioning System (GPS) using a GPS antenna and receiver. The timing information is used to synchronize and maintain an internal clock. The clock then acts as a reference for network time clients.
The Need For Accurate Time
PC’s generally utilize low-quality, low-cost real-time clock components. They keep notoriously poor time. A collection of computers set to the same time can have wildly differing times after only a few hours. This can cause real problems for many applications and economic activities.
The Network Time Protocol
The Network Time Protocol (NTP) is a standard protocol for the transfer of time on a computer network. Originally designed by David L. Mills of the University of Delaware back in 1985, it is one of the oldest protocols still in regular use today. The protocol is a hierarchical protocol designed to provide a means of synchronizing client computers to a time server. The highest stratum time server references a very accurate hardware clock such as GPS, GLONASS or Galileo to maintain network time.
Using The Global Positioning System (GPS) For Accurate Time
The Global Positioning System is a satellite based navigation and positioning system operated and maintained by the US government. Three segments make up the system: space, control and user.
The space segment is a satellite system consisting of a constellation of 24 orbiting satellites. They are positioned so that every point on Earth can see at least 4 satellites at any one time. The satellites transmit time and position information to user segments.
The control segment is made up of a number of command stations that ensure correct operation of the system and periodically adjust satellite atomic clocks.
The user segment is the receivers and equipment used to provide time and positioning information based on the satellite transmissions.
GPS provides free-to-air positioning and navigation services. The system is widely used by marine and vehicle navigation systems.
In addition to providing positioning information, the GPS system also provides very accurate time. Each GPS satellite has multiple atomic clocks on board, which supplements GPS signals with very precise time data. Each atomic clocks is periodically adjusted to a master clock based on Earth to maintain synchronization of all the satellites.
GPS receivers decode the satellite signals to provide timing information synchronized to the atomic clocks. This enables equipment to obtain time accurate to billionths of a second without the expense of an atomic clock.
GPS NTP Time Server Applications
Precise time is critical to many applications and activities. Transaction processing, financial trading, data logging, machine monitoring and many other applications all rely on time synchronization. The availability of free-to-air atomic time has led to huge cost savings for companies and applications that rely on precise time. Lower cost hardware has also led to new and innovative applications.
Power companies are placing GPS NTP time servers in power plants and substations. This allows them to locate a power line break by analyzing the exact time of a fault as it propagates through the electrical grid.
Instrumentation often relies on accurate time. Equipment that may be located very far apart may require synchronization in order to act on or monitor linked events. For example, weather stations located in different parts of a country require synchronized instrumentation in order to accurate track weather systems.
Large institutions providing financial services and trading use GPS to very precisely time-stamp transactions. This provides a traceable record of the order of events as they occurred.
GPS Time Server Hardware
Equipment can receive GPS time and positioning information by using an antenna and receiver. The receiver is generally integrated into the equipment. The antenna is usually separate and connected to the receiver using a coax cable.
Ideally, a GPS antenna should be located where it has clear unobstructed view of the sky, such as a rooftop. TimeTools GPS time server receivers operate down to a single satellite in view. This allows an antenna to be positioned in a window or on the side of a building, saving on installation costs. Our receivers also have a high sensitivity mode which, in some circumstances, allows an antenna to be located inside a building with no line of sight to the sky.
Alternative GNSS Systems
There are other Global Navigation Satellite Systems in addition to GPS. The GLONASS system is the Russian equivalent to the GPS system. Beidou is the Chinese system. While the eagerly anticipated European Galileo system comes online in 2019. These systems can be used in combination with each other to provide high-reliability redundant timing.
Network Time Server Appliances
TimeTools T300 GPS NTP Time Server
The T300 is a cost-effective GPS network time server in a 1U high 19 inch rack-mountable enclosure.
The T300 provides an accurate source of time for computer networks of any size and can synchronize any NTP or SNTP compatible system.
The device features a high-sensitivity GPS receiver that can synchronize down to a single satellite in view. This provides cost savings by allowing antenna location on the side of a building or in a window rather than on a rooftop. Also, the high-sensitivity mode, in some circumstances, allows antenna location inside a building.
TimeTools T550 GPS Time Server
The T550 is a Multi-GNSS network time server. It can utilize GPS, GLONASS, Beidou and Galileo satellite systems to provide a high-reliability redundant time reference. The device can synchronize to within a few microseconds of UTC and support up to 100,000 NTP\SNTP clients.
TimeTools T100 GPS Network Time Server
TimeTools T100 is a very cost-effective GPS referenced NTP server in a compact enclosure. It requires 7.5V DC power, which is provided by a supplied AC mains adapter. The T100 provides an accurate source of time for computer networks and can synchronize any NTP or SNTP compatible system.