Advanced bridge instrument for the measurement of the phase noise and of the short-term frequency stability of ultra-stable quartz resonators

This article reports on the advances in the characterization of an instrument intended to test 5 MHz and 10 MHz crystal resonators packaged in HC40 enclosure, that used for the high-stability space resonators. Improvements concern the design of new double ovens, the reduction of the residual carrier, a lower drift, and a modified calibration process. The instrument sensitivity, that is, the background phase noise converted into Allan deviation, is of 10^-14.