Ultrasonic sensing system

Claim 2

An ultrasonic sensing system for measuring a given parameter, said system comprising: a sensor having an acoustic resonance frequency which varies as a predetermined, relatively continuous function of said parameter; signal coupling means, including at least one electroacoustic transducer, for applying acoustic energy to said sensor and for detecting acoustic energy present in said sensor; an electrical pulse generator interconnected with said signal coupling means for applying single interrogating pulses to said sensor, each such pulse having a duration which is in the order of T/2 where T is the period of the nominal resonance frequency of said sensor; and means interconnected with said signal coupling means and operative following an interrogating pulse for determining the frequency of ringing induced in said sensor by the pulse, the frequency so determined being indicative of the value of said parameter.

Claim 3

A system as set forth in claim 1 wherein the same transducer is employed for applying acoustic energy to and detecting acoustic energy in said sensor.

Claim 4

A system as set forth in claim 2 wherein said transducer is coupled to said sensor through a lead-in providing a delay which is substantially longer than the nominal resonance period T.

Claim 5

A system as set forth in claim 1 the resonance frequency of said sensor varies as a function of temperature whereby the frequency determined by said frequency determining means is indicative of the temperature of said sensor.

Claim 6

A system as set forth in claim 1 wherein the frequency determined by said frequency determining means is indicative of the modulus of elasticity of the material of said sensor.

Claim 7

A system as set forth in claim 1 wherein said frequency determining meAns comprises timing means for measuring the period of the frequency of ringing.

Claim 8

A system as set forth in claim 1 wherein said frequency determining means includes a gate circuit for selectively passing signals from said transducer and a delay circuit for opening said gate only after a predetermined delay following an interrogating pulse.

Claim 9

A system as set forth in claim 7 where the delay provided by said delay circuit includes a portion permitting transient effects in the ringing induced by an interrogating pulse to die out.

Claim 10

A system as set forth in claim 8 wherein said transducer is coupled to said sensor through a lead-in providing a delay which is substantially longer than the nominal resonance period T and wherein the delay provided by said delay circuit includes a portion permitting said interrogating pulse to reach said sensor through said lead-in and for signals returned from said sensor to reach said transducer through said lead-in.

Claim 11

An ultrasonic sensing system for measuring a given parameter, said system comprising: a sensor having an acoustic resonance frequency which varies around a nominal value as a predetermined, relatively continuous function of said parameter; an electroacoustic transducer for applying acoustic energy to said sensor and for detecting acoustic energy present in said sensor; an electrical pulse generator interconnected with said transducer for applying single interrogating pulses to said sensor, each such pulse having a duration which is in the order of T/2 where T is the period of the nominal resonance frequency of said sensor; and timing means interconnected with said transducer and operative after a predetermined delay following an interrogating pulse for measuring the interval required for a predetermined number of cycles of ringing induced in said sensor by the pulse, the interval so measured being indicative of the value of said parameter.

Claim 12

An ultrasonic sensing system for measuring a given parameter, said system comprising: a sensor having an acoustic resonance frequency which varies around a nominal value as a predetermined, relatively continuous function of said parameter; an electroacoustic transducer for applying acoustic energy to said sensor and for detecting acoustic energy present in said sensor; an electrical pulse generator interconnected with said transducer for applying single interrogating pulses to said sensor, each such pulse having a duration which is in the order of T/2 where T is the period of the nominal resonance frequency of said sensor; and timing means interconnected with said transducer and operative after a predetermined delay following an interrogating pulse for measuring the interval required for a predetermined number of cycles of ringing induced in said sensor by the pulse, the interval so measured being indicative of the value of said parameter.