The global positioning system (GPS) is composed of a network of satellites that orbit the earth at an altitude of about 11,625 miles. Each satellite is equipped with up to four atomic clocks which measure time by counting oscillations of a certain type of
This timing information is obtained by GPS receivers which require precise time to compute their distance to each satellite and ultimately their position on earth. GPS clocks utilize the same technology to determine accurate time. Contrary to ordinary GPS receivers which focus on making
positioning information available to the user, GPS clocks focus on making timing information available at precise intervals.
PresenTense Time Client allows you to synchronize to GPS clocks and ordinary GPS receivers via the industry standard NMEA 0183 protocol, turning your PC into an accurate time client on your local area network. A typical network time synchronization scenario using GPS
technology is depicted in the diagram shown below.
The above situation depicts a portable GPS receiver being used with PresenTense Time Server and PresenTense Time Clients. In certain applications, it is desirable to only synchronize one device so PresenTense Time Client can also be used in the following situation.
In order to be compatible with PresenTense Time Client, GPS receivers must emit NMEA sentence at one or two second intervals. Special support is included for the Garmin GPS 2 Plus, the Garmin 38 and Globalsat BU-353 GPS receivers.
See also Local GPS Receivers