Instrument for direct measurement of the velocity of sound in a fluid

Claim 2

An instrument for measuring the velocity of sound in a body of water, said instrument comprising a streamlined structure having a weighted nose section and a streamlined tail section, a first omnidirectional electroacoustic transducer for radiating sound at first frequency into the water surrounding said streamlined structure, said electroacoustic transducer having a sound-radiating surface smoothly blended into outer surface contour of said streamlined structure, a second electroacoustic transducer for radiating acoustic signal bursts of sound at a predetermined frequency which is greater than said first frequency, a sound-reflecting target means rigidly mounted in the path of said second electroacoustic transducer, means for adjusting the distance between said target sand said second electroacoustic transducer, means for driving said second electroacoustic transducer to cause the radiation of acoustic signal bursts of said predetermined frequency, means responsive to the interception of said acoustic signal burst by the target for reactivating said driving means for triggering the next acoustic signal burst, whereby said acoustic signal bursts recur at a repetition rate jointly dependent up on the distance between the target and said second transducer means and upon the velocity of sound in the medium between the target and said second transducer means, means for converting said repetition rate frequency into an alternating-current signal having a frequency representative of said repetition rate, and means driving said first transducer means at said alternating-current frequency.

Claim 3

The invention of claim 1 wherein said target includes a third electroacoustic transducer for converting said acoustic signal bursts of sound into electrical signals, and means for applying said last named electrical signals to control said converting means for establishing said alternating-current signal.

Claim 4

The invention of claim 2 wherein said second and third electroacoustic transducers are mounted side by side on the nose section of said streamlined structure, and said reflecting target is rigidly located at a distance away from said nose section.

Claim 5

The invention of claim 3 wherein said target is mounted on a rigid frame structure fixed to said nose section.

Claim 6

The invention of claim 4 and means in said frame structure for making fine adjustments of the distance to said target.

Claim 7

The invention of claim 5 characterized in that the temperature coefficient of linear expansion of the material of the frame structure is less than the coefficient of expansion of the material of the target structure with respect to said distance.

Claim 8

The invention of claim 1 wherein said target comprises a third electroacoustic transducer operated responsive to the receipt of the predetermined frequency of the acoustic signals generated by said second transducer, said third transducer being rigidly mounted in a spaced-apart relationship with respect to said second electroacoustic transducer means, and mechanical means for adjusting said spaced-apart relationship.

Claim 9

The invention of claim 7 characterized in that said mechanical adjustment means permits a variation in said spaced-apart relationship over a linear distance of approximately one-tenth yard to one-tenth meter.

Claim 10

The invention of claim 7 wherein said second and said third electroacoustic transducers are located on the outside surface of said streamlined structure and along generally the longitudinal axis of said streamlined structure.

Claim 11

The invention of claim 1 wherein said streamlined structure has a generally round cross section, said first electroacoustic transducer being a polarized ceramic of tubular shape blended into a circumferential wall surface of said streamlined structure.

Claim 12

The invention of claim 10 further characterized in that said ceramic tube has an outside diameter lying within the approximate range of 1 1/2 to 2 inches and further characterized in that the frequency of said alternating-current signal lies within the approximate range of 15-30 kHz.

Claim 13

The invention of claim 10 further characterized in that said ceramic tube is made of polarized lead zirconate titanate and the height of the ceramic tube lies within the approximate range of one-half to one-fourth times the diameter of the tube.

Claim 14

An instrument for measuring the velocity of sound in a body of water, said instrument comprising a streamlined structure having a generally round cross section, a weighted nose section, and a streamlined tail section, a first omnidirectional electroacoustic transducer comprising a polarized ceramic of tubular shape for radiating sound at first frequency into the water surrounding said streamlined structure, said electroacoustic transducer having a sound-radiating surface with the outer wall of said tube circumferentially and smoothly blended into the outer surface contour of said streamlined structure, a second electroacoustic transducer for radiating bursts of sound at a predetermined frequency which is greater than said first frequency, a sound-reflecting target means rigidly mounted in the path of said second electroacoustic transducer, means for adjusting the distance between said target and said second electroacoustic transducer, means for driving said second electroacoustic transducer to cause the radiation of acoustic signal bursts of said predetermined frequency means responsive to the interception of said acoustic signal burst by the target for reactivating said driving means for triggering the next acoustic signal bursts, whereby said acoustic signal bursts recur at a repetition rate jointly dependent upon the distance between the target and said second transducer means and upon the velocity of sound in the medium between the target and said second transducer means, means for converting said repetition rate frequency into an alternating-current signal having a frequency representative of said repetition rate, means driving said first transducer means at said alternating current frequency, said nose section comprising a weighted cylindrical body section, said first electroacoustic transducer comprising a tubular element having an outside and inside diameter, said cylindrical body section being reduced in diameter to provide circumferential dimensional clearance for receiving the inside diameter of said first transducer, a circular disk member shaped for rigid coaxial assembly with the cylindrical body section, said circular disk being undercut at its periphery to a depth of reduced diameter having approximately the same dimension as the reduced diameter of said cylindrical body section, said first transducer being secured within the recessed cylindrical space provided by the undercut peripheries, electrical conductor means connected to said first transducer and passing through said disk member, fastening means for securing the axial alignment of said nose subassembly, said first transducer, said disk member, said tail section comprising a generally hollow tapered streamlined housing, electronic circuit means located within said housing, said electronic means including output terminal for providing an oscillating electrical power for driving said first transducer, and means for rigidly securing said tail section housing in axial alignment to the periphery of said disk member, thereby joining said two subassemblies.

Claim 15

An instrument for measuring the velocity of sound in a body of water, said instrument comprising a streamlined structure having a generally round cross section, a weighted nose section, and a streamlined tail section, a first omnidirectional electroacoustic transducer comprising a polarized ceramic of tubular shape for radiating sound at first frequency into the water surrounding said streamlined structure, said electroacoustic transducer having a sound-radiating surface with the outer wall of said tube circumferentially and smoothly blended into the outer surface contour of said streamlined structure, a second electroacoustic transducer for radiating bursts of sound at a predetermined frequency which is greater than said first frequency, a sound-reflecting target means rigidly mounted in the path of said second electroacoustic transducer, means for adjusting the distance between said target and said second electroacoustic transducer, means for driving said second electroacoustic transducer to cause the radiation of acoustic signal bursts of said predetermined frequency means responsive to the interception of said acoustic signal burst by the target for reactivating said driving means for triggering the next acoustic signal bursts, whereby said acoustic signal bursts recur at a repetition rate jointly dependent upon the distance between the target and said second transducer means and upon the velocity of sound in the medium between the target and said second transducer means, means for converting said repetition rate frequency into an alternating-current signal having a frequency representative of said repetition rate, means driving said first transducer means at said alternating current frequency, said nose section comprising a weighted cylindrical body section, said first electroacoustic transducer comprising a tubular element having an outside and inside diameter, said cylindrical body section being reduced in diameter to provide circumferential dimensional clearance for receiving the inside diameter of said first transducer, a circular disk member shaped for rigid coaxial assembly with the cylindrical body section, said circular disk being undercut at its periphery to a depth of reduced diameter having approximately the same dimension as the reduced diameter of said cylindrical body section, said first transducer being secured within the recessed cylindrical space provided by the undercut peripheries, electrical conductor means connected to said first transducer and passing through said disk member, fastening means for securing the axial alignment of said nose subassembly, said first transducer, said disk member, said tail section comprising a generally hollow tapered streamlined housing, electronic circuit means located within said housing, said electronic means including output terminal for providing an oscillating electrical power for driving said first transducer, and means for rigidly securing said tail section housing in axial alignment to the periphery of said disk member, thereby joining said two subassemblies.

Claim 16

A free-falling instrument for measuring the velocity of sound in a body of water, said instrument comprising velocity-sensor means for instantaneously converting the speed of sound in the body of water into a first electrical quantity, pressure-sensor means for instantaneously converting the water pressure acting on said free-falling instrument into a second electrical quantity, means for converting said first electrical quantity to a first oscillatory electrical signal of frequency f1, means for converting said second electrical quantity to a second oscillatory electrical signal oF frequency f1, which is widely separated from the frequency f1, means for combining the two oscillatory electrical signals so that the lower frequency signal modulates the higher frequency signal, electroacoustic-transducer means for converting said modulated electrical signals to corresponding acoustic signals which are radiated outwardly into said body of water, and means for applying said modulated electrical signal to said electroacoustic-transducer means.

Claim 17

A free-falling instrument for measuring the velocity of sound in a body of water, said instrument comprising velocity-sensor means for instantaneously converting the speed of sound in the body of water into a first electrical quantity, pressure-sensor means for instantaneously converting the water pressure acting on said free-falling instrument into a second electrical quantity, means for converting said first electrical quantity to a first oscillatory electrical signal of frequency f1, means for converting said second electrical quantity to a second oscillatory electrical signal oF frequency f1, which is widely separated from the frequency f1, means for combining the two oscillatory electrical signals so that the lower frequency signal modulates the higher frequency signal, electroacoustic-transducer means for converting said modulated electrical signals to corresponding acoustic signals which are radiated outwardly into said body of water, and means for applying said modulated electrical signal to said electroacoustic-transducer means.

Claim 18

The invention of claim 14 and a receiving hydrophone for converting said acoustic signals into electrical signals, means for separating said frequencies f1 and f2 from said electrical signals, and means for simultaneously recording said separated frequencies as a function of time.

Claim 19

An instrument for measuring the velocity of sound in a body of water, said instrument comprising a hull having a positive buoyancy, whereby said instrument rises to the surface when launched from a submerged submarine, said instrument further comprising a velocity-sensor means for instantaneously converting the speed of sound in the body of water into a first electrical quantity, pressure-sensor means for instantaneously converting the water pressure acting on said free-rising instrument into a second electrical quantity, means for converting said first electrical quantity to a first oscillatory electrical signal of frequency f1, means for converting said second electrical quantity to a second oscillatory electrical signal of frequency f2, which is widely separated from the frequency f1, means for combining the two oscillatory electrical signals so that the lower frequency signal modulates the higher frequency signal, electroacoustic transducer means for converting said modulated electrical signals to corresponding acoustic signals which are radiated outwardly into said body of water, and means for applying said modulated electrical signal to said electroacoustic transducer means.

Claim 20

An instrument for measuring the velocity of sound in a body of water, said instrument comprising a hull having a positive buoyancy, whereby said instrument rises to the surface when launched from a submerged submarine, said instrument further comprising a velocity-sensor means for instantaneously converting the speed of sound in the body of water into a first electrical quantity, pressure-sensor means for instantaneously converting the water pressure acting on said free-rising instrument into a second electrical quantity, means for converting said first electrical quantity to a first oscillatory electrical signal of frequency f1, means for converting said second electrical quantity to a second oscillatory electrical signal of frequency f2, which is widely separated from the frequency f1, means for combining the two oscillatory electrical signals so that the lower frequency signal modulates the higher frequency signal, electroacoustic transducer means for converting said modulated electrical signals to corresponding acoustic signals which are radiated outwardly into said body of water, and means for applying said modulated electrical signal to said electroacoustic transducer means.

Claim 21

The instrument of claim 14 and calibrating means associated with said instrument for adjusting a critical distance associated with said velocity-sensor means, said critical distance extending between an electroacoustic transducer and a target on said instrument, said calibrating means comprising a body of water in which the velocity of sound is accurately known, means for reading the velocity of sound as measured by the instrument being calibrated, and means for adjusting the critical distance until the velocity of sound as measured by the instrument agrees with the known velocity of sound.

Claim 22

An instrument for measuring the velocity of sound in a body of water, said instrument comprising a streamlined structure having a weighted nose section and a streamlined tail section, a first omnidirectional electroacoustic transducer for radiating sound at a first frequency into the water surrounding said streamlined structure, said electroacoustic transducer having a sound-radiating surface smoothly blended into the outer surface contour of said streamlined structure, a second electroacoustic transducer for radiating bursts of sound at a predetermined frequency more than 10 times greater than said first frequency, a sound-reflecting target means rigidly mounted in the path of said second electroacoustic transducer, means for adjusting the distance between said target and said second electroacoustic transducer, means for driving said second electroacoustic transducer to cause the radiation of acoustic signal bursts of said predetermined frequency, means responsive to the interception of said acoustic signal burst by the target for reactivating said driving means for triggering the next acoustic signal burst, whereby said acoustic signal bursts recur at a repetition rate jointly dependent upon the distance between the target and said second transducer means and upon the velocity of sound in the medium between the target and said second transducer means, means for converting said rEpetition-rate frequency into an alternating-current signal having a frequency representative of said repetition rate, and means driving said first transducer means at said alternating-current frequency.

Claim 23

An instrument for measuring the velocity of sound in a body of water, said instrument comprising a streamlined structure having a weighted nose section and a streamlined tail section, a first omnidirectional electroacoustic transducer for radiating sound at a first frequency into the water surrounding said streamlined structure, said electroacoustic transducer having a sound-radiating surface smoothly blended into the outer surface contour of said streamlined structure, a second electroacoustic transducer for radiating bursts of sound at a predetermined frequency more than 10 times greater than said first frequency, a sound-reflecting target means rigidly mounted in the path of said second electroacoustic transducer, means for adjusting the distance between said target and said second electroacoustic transducer, means for driving said second electroacoustic transducer to cause the radiation of acoustic signal bursts of said predetermined frequency, means responsive to the interception of said acoustic signal burst by the target for reactivating said driving means for triggering the next acoustic signal burst, whereby said acoustic signal bursts recur at a repetition rate jointly dependent upon the distance between the target and said second transducer means and upon the velocity of sound in the medium between the target and said second transducer means, means for converting said rEpetition-rate frequency into an alternating-current signal having a frequency representative of said repetition rate, and means driving said first transducer means at said alternating-current frequency.