ULISS project: 2013 progress report

The ULISS Cryogenic Sapphire Oscillator (CSO) offers unprecedented short-term frequency performances. It was specially designed to be transportable by car in order to test this new technology in different European sites. During the last 18 months, it was used to qualify with success several high stability frequency sources. In February 2013, a new measurement campaign was lead at CNES, Toulouse (France) to qualify the flight model of the frequency synthesis of the PHARAO clock. During the same period we built a second CSO unit based on the same design and conducted new characterisations of frequency stability and environmental sensitivity. Optimisation of the system has led to an improved frequency stability reaching currently better than 1×10^-15 at 10,000 s integration times. Eventually we developed a new low phase noise and high-resolution frequency synthesis delivering 10 GHz, 100 MHz and 9.192 GHz ultra stable signals. In this paper we draw a progress report on the ULISS project, updating performances and describing the latest experiments conducted with our CSO in different sites in Europe.