Lamplight Stabilization for GPS Rb Atomic Clocks via rf-Power Control.

Recent evidence indicates that the signal-in-space user-range-error (SIS-URE) for GPS is strongly influenced by the satellite atomic clock's Rb lamplight intensity jumps. Following a proposal by Bloom and Bell, we have implemented rf-power control of an rf-discharge lamp of the type employed in Rb atomic frequency standards (RAFS). Since Rb lamplight intensity jumps are mapped onto the clock's output frequency via the light-shift effect, stabilization of the Rb light emitted by the lamp has the potential to significantly improve the RAFS' long-term frequency-stability, and hence the GPS SIS-URE. Here, we not only demonstrate that rf-power control of the discharge-lamp is possible, but that by employing such control the fluctuations in Rb lamplight intensity can be reduced by orders of magnitude providing a pathway for significant improvement in global navigation satellite systems.