In the time and frequency transfer and dissemination field, it is important to provide cost effective remote frequency calibration services with an uncertainty of around 10-12 for end users. It is also required to develop ultra precise transfer methods with an order of 10-15 or better uncertainty for the comparison between ultra stable frequency standards which are under developing. This study shows two methods using optical fiber networks to satisfy these demands. First, it is an economical remote calibration method using existing synchronous optical fiber communication networks. The measured frequency stability (the Allan deviation) of the transmission clock is 2×10-13 for an averaging time of one day. The result indicates the method is promising for the simple remote frequency calibration service. Second, it is an ultra precise two-way optical fiber time and frequency transfer method using a newly proposed bi-directional optical amplifier. In this method, wavelength division multiplexing (WDM) signals are transmitted along a single optical fiber. The preliminary measured frequency stability is less than 10-15 (τ=10 4 s) for a 100-km-long fiber with the bi-directional amplifier. It suggests that the method has capability for improving International Atomic Time (TAI) and Coordinated Universal Time (UTC).

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This paper aims at the total design of synchronizing clock phase quality in a master‐slave synchronization network and studies the clock path phase errors. In master‐slave synchronization, reference clock distribution paths are a major source of phase errors. It is useful to examine the phase errors using Time Interval Error (TIE), specified in units of time. In this paper, the TIE of clock paths containing multiplexers, digital transmission lines and digital synchronous terminals is analyzed. Then measurements taken for multiplexers are presented by varying a stuffing ratio. Field data taken for a 7‐link clock path, the longest effective link path in Japan, shows that in practice a TIE of less than 100 ns over a 102 – 103 s measurement period is measured, which agrees well with theoretical data.

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