Gabe H. Iyanu, He Wang, Zachary Warren, Michael Huang, and James C. Camparo, The Aerospace Corporation

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Abstract:

To help satellite operators and system engineers understand and resolve flight clock issues, we have built a GPS atomic flightclock simulation and test station in The Aerospace Corporation’s Physical Sciences Laboratories (PSL). Our test station currently has one GPS-IIF flight rubidium atomic frequency standard (RAFS) sitting on a chiller-controlled thermal baseplate and housed in a vacuum chamber. With this testbed we can simulate normal and extreme space flight environments, and collect all telemetry outputs from the RAFS, including those related to clock health. Additionally, we can measure the output frequency of the GPS atomic clock and estimate the clock’s performance. As reported in our previous works, such a laboratory-based atomic flight-clock simulation and test station has proven to be very useful in helping better understand the satellite clock’s operational characteristics and in investigating on-orbit constellation timekeeping issues. In this paper we first describe our GPS flight clock simulation and test station and the measurement methods, and then present examples of the latest experimental results obtained using the test station to study the RAFS clock’s frequency characteristics at various baseplate temperatures, the clock’s intrinsic temperature coefficients and input voltage dependence under simulated space operational conditions.