Data and Time Transfer Using Sonet Radio

The need for precise knowledge of time and frequency has become ubiquitous throughout our society. The areas of astronomy, navigation and high-speed wide-area networks are among a few of the many consumers of this type of information. GPS has the potential to be the most comprehensive source of precise timing information developed to date however, the introduction of Selective Availability has made it difficult for many users lo recover this information from the GPS system with the precision required for todays systems. The system described in this paper is a SONET Radio Data and Time Transfer System. The objective of this system is to provide precise time and frequency information to a variety of end-users using a two-way data and time-transfer system. Although time and frequency transfers have been done for many years, this system is unique in that time and frequency information are embedded into existing communication traffic. This eliminates the need to make the transfer of time and frequency information a dedicated function of the communications system.