Peter T. H. Fisk

Two-way satellite time and frequency transfer networks in Pacific Rim region

A two-way satellite time and frequency transfer (TWSTFT) network in the Pacific Rim region is under construction to contribute to the calculation of the international atomic time (TAI). Four major time and frequency institutes in this region have been conducting long-term TWSTFT experiments. In addition to these institutes, several others in the region are planning to join the network. A new type of time transfer modem for TWSTFT is also described.

Long-term operation and performance of cryogenic sapphire oscillators

Cryogenic sapphire oscillators (CSO) developed at the University of Western Australia (UWA) have now been in operation around the world continuously for many years. Such oscillators, due to their excellent spectral purity are essential for interrogating atomic frequency standards at the limit of quantum projection noise; otherwise aliasing effects will dominate the frequency stability due to the periodic sampling between successive interrogations of the atomic transition. Other applications, which have attracted attention in recent years, include tests on fundamental principles of physics, such as tests of Lorentz invariance. This paper reports on the long-term operation and performance of such oscillators. We compare the long-term drift of some different CSOs. The drift rates turn out to be linear over many years and in the same direction. However, the magnitude seems to vary by more than one order of magnitude between the oscillators, ranging from 1014 per day to a few parts in 1013 per day

Two-way satellite time transfer network in Pacific Rim region

A Two Way Satellite Time Transfer (TWSTT) network in the Pacific rim region is under construction to contribute to the International Atomic Time (TAI). Four major Time and Frequency Institutes in this region have been conducting long term TWSTT experiments. In addition to these institutes, several ones in this region are planning to join this TWSTT network.

Development and applications of a traceable time-transfer system

The National Measurement Institute, Australia (NMIA) has been developing GPS Common View (GPSCV) time-transfer systems since the late 1990s. These provide traceability to UTC(AUS) for laboratory frequency references and network time. We describe our system, including advice on the use of low-cost receivers for GPSCV, summarise our 15 years of providing services based on it and conclude with a summary of current and future developments.