Meteorological data encoder for measuring atmospheric conditions
AssigneeA.I.R., Inc.
InventorsDavid B. Call, James A. Nolan, Steven J. Lassman
Life of this patent
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Abstract
A radiosonde has a novel and improved measuring circuitry for measuring atmospheric conditions, such as, temperature, humidity and pressure through the direct conversion of resistance and capacitance values into binary numbers. The binary numbers are transmitted in digital form along with calibration coefficients to a remote ground station. The measuring circuitry can be mounted on the same substrate with the pressure transducer, and the electrical connections between the pressure transducer and measuring circuitry are simplified by utilization of an offset diaphragm, pressure cell arrangement.
Claims18
In a radiosonde wherein a transmitter is operative to transmit digital data from a microprocessor to a base station, the improvement comprising:
- a reference resistor;
- at least one variable resistor means whose resistance varies in direct proportion to one of a plurality of sensed meteorological conditions including temperature and humidity, a normally open switch in series with each of said reference resistor and said variable resistor means;
- a capacitor having a fixed time constant connectable to each of said reference resistor and said variable resistor means;
- means for charging said capacitor when each said switch is closed between said capacitor and one of said reference and said variable resistor means, said means for charging said capacitor including a bipolar transistor and control signal means from said microprocessor operative to turn said transistor off to initiate charging of said capacitor;
- comparator means responsive to charging of said capacitor to a predetermined level in order to switch said comparator means to an opposite state;
- and
- time interval measuring means including counter means for generating a binary number as a measurement of the time required to switch said comparator means for transmittal to said base station.
In a radiosonde wherein a transmitter is operative to transmit digital data from a microprocessor to a base station, the improvement comprising:
- a resistance measuring circuit including a reference resistor, at least one variable resistor means whose resistance varies in direct proportion to one of a plurality of sensed meteorological conditions including temperature and relative humidity, a normally open switch in series with each of said reference resistor and said variable resistor means, a capacitor having a fixed time constant connectable to each of said reference resistor and said variable resistor means, means for charging said capacitor when each said switch is closed between said capacitor and one of said reference and said variable resistor means, and comparator means responsive to charging of said capacitor to a predetermined level in order to switch said comparator means to an opposite state;
- time interval measuring means including counter means in said microprocessor for generating a binary number as a measurement of the time required to switch said comparator means;
- and
- a capacitance measuring circuit including a pressure cell having a capacitance which varies with changes in atmospheric pressure, and high and low fixed reference capacitors each in parallel with said pressure cell, switching means in series with each of said pressure cell and said reference capacitors, oscillator circuit means whose input is connected in common to each of said switches, control signal means for sequentially closing each of said switches to charge each said reference capacitor and said pressure cell capacitance in succession, said oscillator circuit means having a period of oscillation proportional to the rate of discharge of each of said reference capacitors and said pressure cell capacitance, and said time interval measuring means operative to generate a binary number representing the period of oscillation of said oscillator circuit means in discharging each said reference capacitor and said pressure cell capacitance in said capacitance measuring circuit.
In a radiosonde wherein a variable capacitance, pressure responsive transducer includes a non-conductive substrate having metal diaphragms hermetically secured to opposite surfaces of said substrate in overlapping spaced relationship to a respective fixed capacitor on said opposite surfaces, the improvement comprising:
- said diaphragms having peripheral boundaries disposed in offset but partially overlapping relation to one another and said plates disposed in offset but partially overlapping relation to one another, a first conductor extending through said substrate electrically interconnecting overlapping portions of said plates, a portion of one of said plates extending along one of said opposite surfaces beyond the peripheral boundary of said diaphragm on the other of sad opposite surfaces, and a second conductor extending from said portion into communication with the other of said opposite surfaces;
- and
- an electronic measuring circuit mounted externally of said transducer including an external lead connecting said electronic measuring circuit to said second conductor.
Dependencies are inferred from the claim text.