In a quartz barometer untilizing the temperature dependence of the resistance of a quartz oscillator at resonance, the present invention is directed to provide a circuit which compensates for the temperature change of the resistance at resonance by connecting a temperature-dependent resistor in series with a quartz oscillator thereby enabling said quartz barometer to measure gas pressure much more accurately.
A pressure or vacuum gauge measures pressure of gas within a chamber. A quartz oscillator is disposed within the chamber for undergoing oscillation having a frequency dependent on a body temperature thereof. A constant heat source is disposed in spaced relation to or directly on the temperature-dependent quartz oscillator for heating the same to hold the body temperature thereof which is dependent on the pressure of surrounding gas. The oscillating frequency of the quartz oscillator is converted into a signal indicative of the pressure of the gas.
The present invention deals with a quartz-type gas pressure gauge which utilizes resonance of a quartz vibrator that changes depending upon the pressure, wherein the quartz vibrator is of the type of tuning fork obtained from a Z-plate of quartz crystal that is cut at an angle of greater than 1.degree.50' with respect to the Y-axis, in order to prevent the occurrence of erroneous measurement that will be caused by the change of ambient temperature particularly in low pressure regions.
The invention refers to a measurement device for measuring air pressure by means of a pressure sensor that can be excited to natural oscillations. In order to eliminate the influence of relative humidity on the air pressure to be measured, it is suggested that a humidity sensor be used, preferably in the form of a condensor with a humidity sensitive polymer as a dielectric, and that the identified pressure values be corrected for the influence of the humidity.
An accumulating altimeter includes a programmable accumulator which selectively accumulates altitude changes from a reference altitude in accordance with accumulation thresholds. Altitude changes in the direction of interest, e.g. altitude gains, are accumulated once a non-opposing accumulation threshold has been reached. Opposing altitude changes which are less than an opposing accumulation threshold are used to offset non-opposing changes. Opposing altitude changes which are equal to or greater than the opposing accumulation threshold are used to re-establish the reference altitude, whereafter accumulation of non-opposing altitude changes resume after the non-opposing accumulation threshold has been reached.
A space vehicle includes a temperature sensitive oscillator carried by a housing. The temperature sensitive oscillator includes a radiation hardened inverting gain circuit, such as a comparator, able to withstand radiation in an ambient space environment, and a thermistor connected to the radiation hardened inverting gain circuit so that an output frequency of the temperature sensitive oscillator varies based upon a temperature of the thermistor. Also, a frequency counter is preferably connected to the temperature sensitive oscillator for generating a digital output signal representative of a sensed temperature. The sensed temperature may be used by one or more electronic circuits connected to the frequency counter.
