Phase locked DRO/CRO for space use

A Dielectric Resonator Oscillator (DRO) or Coaxial Resonator Oscillator (CRO) may be phase locked to a Temperature Compensated Crystal Oscillator (TCXO) to produce small, lightweight, rugged oscillators for use in communications spacecraft. These units combine the long term stability and excellent close-in phase noise of crystal oscillators with the superior phase noise of DRO/CRO's at higher offset frequencies. Further advantages of this technique over other techniques (such as a crystal oscillator followed by a multiplier chain) include smaller mass and volume, lower cost, and higher reliability.