Evaluation and Preliminary Results of the New USNO PPS Timing Receiver

Abstract : The U.S. Naval Observatory (USNO) is tasked to provide the Global Positioning System (GPS) with a reliable and stable reference to UTC(USN0). This is accomplished using GPS Precise Positioning Service (PPS) timing receivers with a UTC(USN0) reference input. The USNO monitors GPS Time from all available healthy satellites. On a daily basis, the GPS Time correction, based on the entire constellation with respect to UTC(USNO), is determined and provided to the GPS Master Control Station (MCS) 2nd Satellite Operations Squadron (2 SOPS) at Schriever AFB in Colorado. The USNO s GPS PPS operations have been limited to a single-channel receivel; which only allows tracking of one satellite at a time. Since February 2000, the USNO has been evaluating a 12-channel GPS PPS timing receiver, based on the GPS Monitor Station receiver. The unit is capable of tracking P(Y)-code and removes the effects of Selective Availability (SA). This paper describes the various tests conducted, the receiver s performance, and expected improvements to the USNO GPS PPS operations.