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Oscillators are a fundamental component within electronic timing systems.  

This page provides an overview to explain some of the differing types.

Oscillators with GPS disciplining as time and frequency sources

Oscillators are electronic devices that generate a recurring waveform (the resonance frequency). This frequency is a counter to measure time and so is used extensively in clocks as a frequency reference source. Quartz crystal is the most widely regarded material to use in oscillator circuits because of its general stability characteristics.

Oscillators fulfil a vital role as they are disciplined by the instrument’s primary time reference source so that in the event of a signal interruption, a properly calibrated time reference signal is maintained.  

The stability characteristics of the oscillator will determine the accuracy of both the time and frequency output of the timing system over time and temperature.  Oscillator choice therefore very much depends upon the required accuracy performance of the timing system when operating without it’s Trusted Time Source for a given period of time or temperature range.  

Operating without a primary timing source as an oscillator disciplining reference is known as Holdover.

Common Oscillator Grades & Options :

TCXO – Temperature Compensated Crystal Oscillator

Temperature can affect oscillator frequency variations leading to inaccuracies. The TCXO uses an electronic circuit to compensate for changes in ambient temperature and so benefits from a higher level of stability than a standard quartz crystal oscillator.

OCXO – Oven Controlled Crystal Oscillator

The crystal is enclosed in a temperature-controlled chamber (oven) which results in a very stable environment, and consequenctly a very stable frequency.

Rubidium Oscillators

Rubidium oscillators make use of the atomic resonance of Rubidium (Rb87) to control the frequency of a quartz crystal oscillator.  

This combination provides an extremely high level of frequency stability over time.

Caesium (or Cesium) Oscillators

Caesium is the primary standard for time and frequency measurements used in atomic clocks because the resonance is exactly in line with the definition of a second as defined by the International System of Units (SI).