This paper describes an experiment designed to transfer ments have been conducted [I], [2] previously using satelaccurate time between two widely separated clocks using a VHF satellite Satellite, ATS-1. The experiment used atomic oscillators to maintain accurate time at each station, and the synchronization was accomplished by measuring the round-trip delay times between the stations. The goal of the experiment was to evaluate a V H F system, because of the low-cost ground equipment involved, in contrast to microwave systems. The paper discusses the results and the various factors that contributed to the timing errors. lites with microwave transponders. The present experiment transP'"'der* The &elbte used was the NASA Applications T=h""l"gy was conducted with the ATS-1 VHF transponder. Although the microwave frequency region is ideal from the point of system has an advantage in that relatively simple and lowclocks was achieved to within a few microseconds. view of avoiding atmospheric signal distortion, the VHF cost ground equipment may be used. Synchronization ofthe Manuscript

An experiment performed in late 1967 is reported which investigated the synchronization of widely separated clocks. One-way VHF timing signals were relayed to remote clocks from a reference clock by means of a transponder on a geostationary satellite. The problem of synchronizing clocks using one-way transmission reduces to the problem of predicting the radio propagation delay. The accuracy of predicting the delay was 10 MS or 60 ~.rs depending on the method used. This technique may offer an alternative to transporting atomic standards to geodetic and spacecraft tracking stations around the world in fulfillment of their clock synchronization requirements.

No abstract

Several technology surveys concerning millimeter-wave (MMW) measurement needs and capabilities have been conducted by the National Bureau of Standards (NBS), Boulder Laboratories, and others. The results of some of these studies are summarized. Current MMW standards and calibration capabilities at NBS are reviewed. The lack of national standards in certain frequency bands may lead to problems with the specification, acceptance testing, and calibration of some components and systems.