A frequency and timing subsystem for the ORION mobile unit

Abstract

A mobile surveying instrument in support of the crustal dynamics program measures the length and direction of the distance between sites on the Earth's surface using VLBI techniques operating at microwave frequencies and extragalactic radio sources. The frequency and timing subsystem uses as a frequency standard the hydrogen maser. An important part of the subsystem is a sophisticated automatic system to monitor frequency stability and accumulated clock error.