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US 6,470,757 B2Granted
Ultrasonic flow velocity measuring method
AssigneesHak Soo Chang, Chang Min Tech Co., Ltd.
InventorHak Soo Chang
Life of this patent
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Abstract
An ultrasonic flow velocity measuring method using a transit time difference of continuous sine waves without transmitting/receiving an ultrasonic pulse comprises steps of amplitude-modulating a continuous ultrasonic sine wave carrier into a lower frequency and transiting the amplitude-modulated signal, whenever the ultrasonic transit time is measured; demodulating the amplitude-modulated signal; detecting or discriminating the amplitude-modulated signal from the demodulated signal and measuring a time interval from the moment that the ultrasonic sine wave is amplitude-modulated till the amplitude-modulated signal is demodulated.
Claims10
A method for measuring a flow velocity of a fluid comprising:
- transmitting a first amplitude modulated signal from a first tranducer disposed on one side of a flow of the fluid to a second tranducer disposed on an opposite side of the flow of the fluid at an angle α from the first transducer relative to the
- flow, the first amplitude modulated signal including a first sine wave having an ultrasonic carrier frequency ƒc amplitude modulated by a second sine wave having a frequency ƒm that is less than ƒc for at least a first portion of the second sine wave;
- demodulating the first amplitude modulated signal received by the second transceiver to obtain a first demodulated signal having the frequency ƒm;
- determining a first transit time for the first amplitude signal, the first transit time being equivalent to a time period between a moment that a voltage potential of the second sine wave passes a zero potential during the first portion of the second sine wave and a moment that a voltage potential of the first demodulated signal passes the zero potential during a corresponding portion of the first demodulated signal;
- transiting a second amplitude modulated signal from the second transducer to the first transducer, the second amplitude modulated signal including the first sine wave modulated by the second wave for at least a second portion of the second sine wave;
- demodulating the second amplitude modulated signal as received by the first transceiver to obtain a second demodulated signal having the frequency ƒm;
- determining a second transit time for the second amplitude signal, the second transit time being equivalent to a time period between a moment that a voltage potential of the second sine wave passes the zero potential during the second portion and a moment that a voltage potential of the second demodulated signal passes the zero potential during a corresponding portion of the second demodulated signal;
- and
- determining a flow velocity of the fluid based on the first and second transit times.
6 more elements
An apparatus for a flow velocity of a fluid comprising:
- a first transducer disposed on one side of a flow of the fluid and being adapted to transmit a first amplitude modulated signal and receive a second amplitude modulated signal, the first amplitude modulated signal including a first sine wave having an ultrasonic carrier frequency ƒc amplitude modulated by a second sine wave having a frequency ƒm less than ƒc for at least a first portion of the second sine wave and the second amplitude modulated signal including the first sine wave modulated by the second sine wave for at least a second portion of the second sine wave;
- a second transducer disposed on an opposite side of the flow of the fluid at an angle α from the first transducer relative to the flow and being adapted to receive the first amplitude modulated signal and transmit the second amplitude modulated signal;
- a demodulator in electrical communication with the first and second transducer and being adapted to:
- demodulate the first amplitude modulated signal as received by the second transducer to generate a first demodulated signal;
- and
- demodulate the second amplitude modulated signal as received by the first transducer to generate a second demodulated signal;
- a mechanism for determining a first transit time for the first amplitude signal, the first transit time being equivalent to a time period between a moment that a voltage potential of the second sine wave passes a zero potential during the first portion of the second sine wave and a moment that a voltage potential of the first demodulated signal passes the zero potential during a corresponding portion of the first demodulated signal;
- a mechanism for determining a second transit time for the second amplitude signal, the second transit time being equivalent to a time period between a moment that the voltage potential of the second sine wave passes the zero potential during the second portion of the second sine wave and a moment that a voltage potential of the second demodulated signal passes the zero potential during a corresponding portion of the second demodulated signal;
- and a mechanism for determining a flow velocity of the fluid based at least on the first and second transit times.
6 more elements
Dependencies are inferred from the claim text.