Abstract: A flowmeter system and method comprising device defining a path for the flow of a fluid medium therethrough, first and second spaced apart transducers disposed along said flow path for generating acoustic compression waves (energy) in the flow medium between the transducers with increased transmission times and occurring immediately following the cessation of transmission of the other transducer, and circuitry means for measuring the phase difference in the received acoustic compression waves relative to that transmitted and for producing sum and difference voltage signals dependent upon the sum and differences of the two measured phase differences, the length of time for the generation of energy in the fluid being long enough to allow the energy to equilibrate and to allow more time after initiation of transmission before measurement of the phase difference and the purpose of having the second transmitter generate energy immediately following the cessation of the generation of the prior transducer is to swam

Abstract: The disclosed circuitry for integrating an analog voltage signal with respect to time, t, while simultaneously dividing the integral by time, t, is valuable for use in medical pulmonary analyzers and includes a ramp generator for developing a voltage level proportional to time, a duty cycle modulator for generating an inverted time signal, 1/t, a multiplier for multiplying the analog voltage signal, V, by the inverted time signal, 1/t, followed by an integrator to produce the required output of 1/t .intg.V dt.

Abstract: A flowmeter system having circuitry defining a path for confining the flow of a fluid medium therethrough, first and second transducers disposed along said flow path for generating and receiving acoustic compression waves in the fluid medium between the transducers, a phase lock loop receiver/transmitter system including a voltage controlled oscillator for adjusting the frequency of the acoustic compression waves to maintain the compression wave length constant, a phase detector for measuring the phase difference of the received acoustic compression waves relative to that transmitted and for producing a sum signal proportional to the sum of the measured phase differences to vary the output of said voltage controlled oscillator, circuitry for producing a difference signal proportional to the difference of the measured phase differences representing the direction and magnitude of the flow of the fluid medium as well as changes in its composition and an active filter in the loop for increasing the loop gain of t

Abstract: A flowmeter system having a device defining a path for confining the flow of a fluid medium therethrough, first and second transducers disposed along said flow path for generating and receiving acoustic compression waves in the fluid medium between the transducers, a phase lock loop transmit/receive system including a voltage controlled oscillator for adjusting the frequency of the acoustic compression waves to maintain the compression wave length constant, a phase detector for measuring the phase difference of the received acoustic compression waves relative to that transmitted and for producing a sum signal proportional to the sum of the measured phase differences to vary the output of said voltage controlled oscillator, circuitry for producing a difference signal proportional to the difference of the measured phased differences representing the direction and magnitude of the flow of the fluid medium as well as changes in its composition, and circuitry for adjusting the phase of the transmit signal during i

Abstract: A high speed temperature controlled, microcircuit electrometer comprising a preamplifier with a very high resistance feedback resistor and temperature sensor on a substrate which is temperature controlled by a thermo-electric module on which the substrate is mounted and which is held within a very small temperature range by temperature control circuitry. The preamplifier, feedback resistor, temperature sensor and thermo-electric module are all enclosed in a hermetically sealed, dry gas environment, maintained at an essentially constant temperature, to reduce the effects of hostile environments, such as temperature changes, vibration, contamination, and humidity. This electrometer operates at high speed and is highly responsive to small current values such as ion currents generated by ionized gas molecules in a mass spectrometer.

Abstract: A flowmeter system for measuring the flow and changes in the velocity of sound due to changes in composition or temperature of a fluid medium in a flow tube including transducers which generate acoustic compression waves in the fluid medium, phase lock loop transmitter/receiver circuitry including device for measuring the difference in phase of the acoustic compression waves transmitted upstream relative to that received and for measuring the phase difference of the acoustic compression waves transmitted downstream relative to that received and producing a sum signal dependent upon the sum of the two measured phase differences, device for producing a difference signal proportional to the difference of the two measured phase differences which provides an output signal representing the direction and magnitude of the measured flow device for automatically adjusting the frequency of the acoustic compression waves so that their wave lengths remains constant, said means for automatically adjusting the frequency inc

Abstract: A flowmeter for accurately determining the rate of flow of a gas substantially independent of its molecular composition and also for determining a measure of the velocity of sound in that gas. The gas flows through a transducer assembly. Disposed in the transducer are two cylindrical transducers each capable of producing or responding to acoustic compressions in the gas. The transducers are alternately switched between transmitting and receiving with one transducer at a given instant being used to transmit and the other to receive. The phase difference between the transmitted and the received signal for two successive transmit-receive cycles are stored with the difference between two successive stored phase differences indicating the magnitude and the direction of fluid flow and the sum of the stored phase differences providing a measurement of the velocity sound in that gas.