Frequency stability requirements for space communications and tracking systems

Space communications and tracking systems impose stringent requirements on stable frequency sources. "Flicker" (1/f) noise and environmental modulation are two types of oscillator instability affecting typical space systems performance. Examples of several systems are presented with the source requirements for each. Earth satellite systems impose stability requirements of the order of 10
^-10
over periods of seconds to hours depending on the individual experiment. A typical system requires phase noise of less than 5° rms in a receiver of 12 Hz bandwidth at S-band. An example is presented of a spacecraft transponder which must maintain phase noise below 45° peak-to-peak under vibration of 3g peak from 10 Hz to 10 KHz.