Abstract: A method and apparatus for obtaining an accurate measure of the frequency of an applied signal by generating a pair of independent frequency signals wherein one of the independent frequency signals has a frequency value which is indicative of the operating temperature of the counter. The counter has two modes of operation: a calibration mode and a measurement mode. In the calibration mode, an accurate signal having a preselected frequency value is applied to the counter. The frequency of this signal is measured with reference to the other of the pair of independent frequency signals and this measured value is then algebraically combined with a prestored value that is equivalent to the preselected frequency of the applied signals. The combined value represents the necessary normalized correction factor for any measured frequency when the counter is at the corresponding temperature.

Abstract: A method and apparatus utilizing a quartz crystal resonator with an orientation substantially equal to (yxwl) 21.93.degree./33.93.degree. vibrating simultaneously in two thickness modes to provide a stable frequency signal source. By combining a quartz crystal resonator of the above type with either digital or analog compensation, the frequency-temperature deviation of one of the crystal mode frequencies is used as an internal thermometer and the second crystal mode frequency as a reference frequency signal. The frequency signal for the thermometer function is utilized by the compensation network to stabilize the frequency of the reference signal. Additionally, the analog or digital compensation is accomplished by means of either a curve-fitting routine or an interpolation look-up table routine.

Abstract: A method and apparatus utilizing a quartz crystal resonator with an orientation substantially equal to (yxwl) 21.93.degree./33.93.degree. vibrating simultaneously in two thickness modes to accurately measure temperature and unknown frequencies or to provide a stable frequency signal source. By combining a quartz crystal resonator of the above type with either digital or analog compensation, the frequency-temperature deviation of one of the crystal mode frequencies is used as an internal thermometer and the second crystal mode frequency as a reference frequency signal. The frequency signal for the thermometer function is utilized by the compensation network to correct the measurements made with, or to stabilize, the frequency of the reference frequency signal. Additionally, the analog or digital compensation is accomplished by means of either a curve-fitting routine or an interpolation look-up table routine.