Benefits Of An Ultra Stable Oscillator For Long Coherent Integration

This paper analyzes the benefits of using a precise oscillator during very weak signal acquisition in a static GPS receiver. It is well known that the optimal solution for acquiring weak signals is by extending coherent integration. The major limiting factor, even in the aided case, is the instability of the receiver's local oscillator. This research, to eliminate the local oscillator's instability issue, tests a precise oscillator in a static receiver and focuses on answering the following questions: (i) what else limits the length of coherent integration? (ii) what happens if integration occurs over hundreds of seconds? (iii) how do indoor position results look as a function of increasing coherent integration time? and (iv) what other benefits, other than sensitivity improvement, can one attain from long coherent integration? These questions are addressed by performing experiments using real GPS data collected using an ultra stable oscillator exhibiting Allan deviations of the order of 10(-13) over 1 second, namely the BVA (Boitier a Vieillissement Ameliore) technology based oscillator from Oscilloquartz.