Abstract
A comparison among the cesium clocks of four laboratories remotely located from each other in Japan has been carried on for more than one year using the synchronizing method by the television broadcast.
This paper describes the stability of the comparison via common emission. Since the time dispersion in an ordinary equipement for time comparison was estimated to be larger than that in such passive paths as the atmosphere and coaxial cables, it was expected that better stability of comparison could be attained mainly by improving the equipment. The improvement was brought about by introducing a specially made tuner which has a quartz crystal oscillator as a local one and by realizing better temperature characteristics of the coupling circuit between the TV receiver and the separater of horizontal synchronizing pulse. The frequency stability for one improved equipment was about 1×10-8 τ-1 over the range of the averaging time, τ, from 0.5s to 105s. The time dispersion of the equipment was estimated to be 10ns from the above value.
The frequency stability observed by the comparison of the clocks at National Research Laboratory of Metrology (NRLM) in Itabashi, Tokyo and at Radio Research Laboratories (RRL) in Koganei, Tokyo was about 4× 10-13 τ-1/2 (5 days≤τ≤20 days). The distance from the emission antenna, Tokyo tower, to NRLM is about 11km, that from the antenna to RRL about 21km.
