Crystal resonators as frequency substandards

Methods for the measurement of the resonant frequency of a piezo-electric quartz vibrator are considered, and advantages are shown to be gained by using the phase/frequency response rather than the amplitude/frequency response to determine the resonance point. Equipment is described which can determine the resonant frequency of 100-kc/s quartz vibrators to ± 1 part in 108, provided that the damping of the vibrator is sufficiently low (Q-factor greater than 100 000), The equipment operates only over a narrow frequency range 100 kc/s ± 10 c/s, and has been useful for crystal resonator development studies. It is concluded, also, that quartz resonators may usefully supplement the oscillator units of a large frequency-standard installation.