Chip Scale Atomic Clocks: Benefits to Airborne GNSS Navigation Performance

Abstract

Currently available atomic clocks are too large, power hungry and costly for use onboard GNSS receivers. Chip Scale Atomic Clocks (CSACs) are a promising new technology that is expected to be commercially available in a few years time. These devices are highly-stable atomic clocks in a small, low power and low cost package that may replace less-stable crystal oscillators in GNSS receivers. Previous studies have shown that integrating an atomic clock with a GNSS receiver gives improved navigation performance. This paper presents a study into the expected level of navigation performance that may be achieved with CSACs. A theoretical CSAC error model is constructed based on published performance. The application considered in this study is "clock coasting" in airborne GPS navigation. The results show that "clock coasting" with CSACs results in an improved Dilution of Precision (DOP) for up to 55 minutes under low satellite visibility or poor geometry, compared to a typical crystal oscillator. Results also show that good navigation performance (PDOP < 6) can be achieved for up to 80 minutes in four-satellite navigation with CSAC.