Performance of the new master oscillator and phase reference system at FLASH

The master oscillator (MO) and phase reference system at FLASH must provide several RF reference frequencies to widely spread locations with low phase noise and small long term phase drifts. The phase noise requirement of the 1300 MHz reference is of the order of 0.1 deg. while the short and medium term phase stability are of of the order of 0.1 deg. and 1 deg. respectively. The frequency distribution system employs a temperature stabilized coaxial line for RF power distribution and a fiber optic system for the monitoring of phase drifts. Presented are the the concept, design and performance measured in the accelerator environment.