On Disciplined Oscillators for Traceable Frequency and Time in Metrology and Financial Sectors

Abstract

Laboratory sources for standard frequency, one pulse-per-second (1pps) ticks, and time-of-day information which receive external time signals to control their built-in oscillators are widely used wherever accurate and stable frequency and time optionally with universal synchronization are required. Nowadays, such devices mostly apply the signals received from the Global Positioning System (GPS), but also signals from alternative Global Navigation Satellite Systems (GNSS), e.g. the European Galileo, or from low frequency transmitters, e.g. WWVB in the U.S. or the German DCF77, are used. The first parts of our paper deal with traceability of measurements of frequency and time pulses to Coordinated Universal Time (UTC) and particularly to UTC(PTB), its realization by the Physikalisch-Technische Bundesanstalt (PTB), using a disciplined oscillator (DO) with standard frequency and 1pps outputs. For this purpose, the role of PTB’s weekly published Time Service Bulletin (TSB) is discussed in detail. The metrological steps for establishing and maintaining traceability are described and uncertainty contributions for both aspects, frequency and time pulses, are discussed. In the last part we discuss how to possibly meet financial sector regulations according to the European MiFID II. We present a procedure as a component for the assessment to provide accurate time through telecommunication networks using e.g. the Network Time Protocol (NTP). Our procedure checks outputs of an NTP server to validate that its 1pps output signal, which is considered as the device’s time reference point, is in accordance with specific requirements and that the provided time-of-day via NTP corresponds to local legal time (modulo integer hours).