Oven-controlled crystal oscillators (OCXOs) are used in applications where a very high degree of frequency stability is required. Sometimes these oscillators may even be referred to as temperature-stabilized crystal oscillators, or just crystal ovens.
While crystal oscillators show a high degree of stability even when the outside temperature is varied over a significant range, for some applications even higher levels of temperature stability are required. In these applications, OCXOs may provide the required solution.