Developments of rubidium frequency standards at Neuchatel Observatory

The paper describes developments of novel miniaturized rubidium frequency standards. Two variants stem from the same principal design based upon a magnetron cavity. (1) a very small industrial unit for standard commercial applications. The overall volume of this model is only 0.251 with a mass of 470 g and power consumption of 8 W. This unit is close to industrialization, (2) a rugged spaceborne oscillator designed for operation on various spacecrafts or missions. This model was developed in the framework of ESA´s In-Orbit Technology Demonstration Program. Two units, outcome from the present development, will constitute the main time reference for the Russian RADIOASTRON I space VLBI satellite. For this particular application the short time stability and temperature sensitivity are very important. The measured short time stability is σy=4·10^-12·τ- ^1/2 with 1.6·10^-10 temperature sensitivity over the whole operating range -20°C to 65°C