A Long History of Tracking Time and Synchronization
The precision time, frequency, and synchronization industry began in ancient times with the need for knowing precise time throughout an extended geographic area for observance of religious rituals, warfare, navigation of ships, and ground travel. In most recent history, precise time forged the industrial revolution when it became the control mechanism for world train travel and industry machinery. Only a few decades ago, keeping a relatively accurate time-scale was only possible in limited geographic areas. But with the advent of the GPS satellite navigation system and its on-board master atomic clocks, it is now possible to disseminate precise time (and frequency) to the entire world, synchronizing its users to an accuracy of better than 100 billionth of a second. As a result, the need for precision time and frequency has touched almost every aspect of our lives. In the commercial sector for example, it is the heart of our high-tech society, giving rise to our new world of broadband communications and interconnectivity as well as navigation/positioning capabilities for civil and individual users; and there is no end in sight for applications. In the governmental/military communities, it is the engine that fuels the new military technologies of precise navigation, weapons targeting, and secure communications, command, and operational control.
The Industry Today
The precision time/frequency/synchronization industry today makes use of the GPS system by extracting mainly its precise time capability from the highly accurate and stable atomic clocks on-board each satellite. This is done by using GPS timing receivers and electronically coupling its signals to steer precision oscillators to stay on track in both frequency and resultant time. These sync systems in turn become the heart of the next level system, which use its outputs to generate a host of frequencies and signal framing rates to synchronize the network terminals and its users. For example, sync systems used in cell phone base-stations provide the source for the transmission frequencies that carry the data between cell-sites and the cell phone users, distribute UTC time, and synchronize all the stations in the network so the user’s conversation is seamlessly transferred from one cell site to the next. The biggest users of these precision sync technologies are all the communications related industries, government/military services, and public utilities.