Crystal oven

About: Crystal oven is a research topic. Over the lifetime, 955 publications have been published within this topic receiving 10380 citations. The topic is also known as: oven-controlled crystal oscillator & OCXO.

Frequency aiding method and system for navigation satellite receiver with crystal oscillator frequency hysteresis

Abstract: A method and apparatus for estimating oscillator signal variation due to temperature and for providing an estimated frequency to a GPS receiver in order to assist the GPS receiver to acquire the signals quickly is disclosed. A temperature sensor is closely thermally coupled with the crystal oscillator in the GPS receiver and during GPS tracking mode, when the error in the oscillator signal is known with precision, outer bounds of TCXO frequency at given temperatures are maintained, which may correspond to rising and falling temperature conditions. During acquisition mode, an estimated frequency value is provided to the GPS receiver based on a determined average of these bounds. Optionally, an uncertainty factor associated with the frequency estimated may also be provided. The two bounds take into account the hysteresis effects of the oscillator signal drift due to temperature so that a more accurate initial frequency estimate can be provided to the GPS receiver, thus reducing its average time to first fix.

Low power temperature-controlled frequency-stabilized oscillator

Abstract: A quartz crystal resonator is situated in an enclosure whose interior is substantially a vacuum. A heating element is attached to the crystal surface. A sensor is attached to the crystal enclosure, and may be sandwiched between the crystal enclosure and the circuit board to which the crystal enclosure is attached. A control system converts the sensed temperature into a series of variable width pulses applied to the resonator heating element. Thus, the sensor, control unit and heating element comprise a temperature feedback control system which allows the crystal to operate at or very near its desired temperature. Further, the crystal enclosure may be substantially surrounded by an external material insulator. The external material insulator maximizes thermal resistance between the sensor and the environment in comparison to the thermal resistance between the crystal and the sensor. This choice of relative thermal resistances enables the temperature feedback control system to more closely emulate a closed-loop system possessing the advantages of accuracy and responsiveness. In an especially preferred embodiment, an integrated circuit from a switching power supply may be used in a novel manner to perform certain of the functions in the temperature feedback control loop.

Fast warm-up oven controlled piezoelectric oscillator

Abstract: A process and apparatus are disclosed for heating a piezoelectric crystal sonator by infrared radiation.

The influence of pressure and humidity on the medium and long-term frequency stability of quartz oscillators

Abstract: It is shown that the medium-term frequency stability of four different 5-MHz oscillators controlled by two different types of AT-cut resonators is sensitive to changes in atmospheric moisture and possibly pressure. Stabilizing the pressure and humidity, in addition to the normal parameters in an otherwise controlled laboratory setting, improves the frequency stability for measurement times in the region of hours to days. The mechanism by which fluctuations in moisture and possibly pressure bring about frequency changes is speculated upon, noting that the effect could be due to changes in the thermal gradients, changes in the dielectric constants, or residual leakage between critical circuit elements. A simple test is introduced to determine the relative importance of thermal gradients within air-enclosed ovens. >