Atomic and Quartz Clock Hardware for Communication and Navigation Satellites*

Accurate and stable frequency reference sources are critical for commercial, navigation, military, and scientific space applications. Each piece of flight hardware has requirement-types that are generic such as size, weight, power, and reliability, and requirement-types that are specific to the hardware function. The key requirement-types for frequency reference sources are phase noise and stability. Both are important for satellites, but stability is especially important for navigation satellites. Several levels of frequency references are suitable for space applications. This paper discusses similarities and differences among single distributed oscillators for communications satellites, master oscillator groups for communications systems, and atomic clocks for military and navigation systems.