New miniature ultra-stable oscillators

Due to cost constraints, compactness and stability (thermal, short/mid/long term) requirements, demand for accurate orbitography, positioning, and localization systems, there is a need for new time and frequency references, moving from atomic clocks to piezo devices such as ultra-stable oscillators. Industrialization of recent designs and process control improvements have made possible cost effective solutions which reach very high performance using standard structures and current components. For example, QAS (or BVA 4) crystal performances are now achieved using classical CEPE quartz crystals mounted in an HC 37 holder. The main characteristics at 5 and 10 MHz reached by the use of these crystal resonators in our standard catalogue CFPO1 OCXO are: thermal stability better than 5×10 E -11 from -20 to +60°C; daily ageing less than 2×10 E-11; short term stability better than 3×10 E-13 (Allan variance) from 1s to 30s whilst subjected to a thermal gradient; package style 67×60×40 mm³ (about 0.15 litres); and compatibility with 12/15/24 supply voltage. This paper describes results on this type of device