The BBC Network Radio Time and Frequency Standard and Its Role in the Provision of the Greenwich Time Signal

The BBC has broadcast the Greenwich Time Signal GTS on its networks since 1924. Up to February 1990 this signal was generated by the Royal Greenwich Observatory RGO in England and the BBC was informed that the RCO was moving its location to Cambridge and might not be able to continue to provide the Greenwich Time Service. The BBC in its role of a public service broadcaster believed that a long tradition of providing a time signal to its listeners should be upheld, and US such decided to seek alternative methods of provision. In parallel with the activity an in-house requirement arose to re-engineer time switch equipment and provide new facilities for digital audio project. As both requirements have a common engineering core, a decision was taken to design and procure a Time and Frequency Standard that could generate the Greenwich Time Signal to the same specification adhered to by the RGO, and provide additional time and frequency facilities. This paper discusses initially the concept of time and time frequency dissemination as used in a broadcast network, and follows on to present the details of an engineering solution to the requirements of BBC Network Radio. Trends in international broadcasting and the commercial telecommunications market place point toward the increased use of digital audio for studio networking and terrestrial links. The synchronization requirements in this field we more stringent than that incurred in analogue distribution. This paper will consider what timing systems are needed in these applications and how these requirements are satisfied in the BBC Time and Frequency Standard. Finally this paper will present a fringe benefit of the BBC Network Radio system. This is the ability to obtain UTC time from the system using a mom dial up method from any location in the world. This facility is currently under evaluation within the BBC and if considered viable will be available to other organizations and companies in the near future.