Environmental sensitivities of quartz oscillators.

The frequency, amplitude, and noise of the output signal of a quartz oscillator are affected by a large number of environmental effects. The physical basis for the sensitivity of precision oscillators to temperature, humidity, pressure, acceleration and vibration, magnetic field, electric field, load, and radiation is examined. The sensitivity of quartz oscillators to radiation is a very complex topic and poorly understood. Therefore, only a few general results are mentioned. The sensitivity to most external influences often varies significantly both from one oscillator type to another and from one unit of a given type to another. For a given unit, the sensitivity to one parameter often depends on the value of other parameters and on history. Representative sensitivity to the above parameters is given.

Sensitivity of quartz oscillators to the environment: characterization methods and pitfalls.

The advantages and disadvantages of characterizing a complete quartz crystal oscillator or characterizing only the quartz resonator by using a passive phase bridge are discussed. Measurements of temperature sensitivities, including quasistatic or dynamic thermal conditions, are presented. One important point is how to measure the real temperature of the device under test (quartz crystal, for instance) rather than the temperature of the probe. Methods for measuring acceleration and pressure sensitivities are presented, and spurious effects of temperature changes are considered. Problems are discussed in connection with the measurement of the sensitivity to magnetic fields, and to electric fields. Methods used for measuring these sensitivities and the many pitfalls that can be encountered are the focus of the investigation.