Digital knotmeter and log

Claim 2

Apparatus for measuring the velocity of an object relative to a fluid in which the object is at least partially immersed comprising a pair of confronting transducers coupled to said object along an axis, means for exciting a first of the transducers to propagate signals along said axis toward the second for a predetermined time interval, means for producing a predetermined number of signals following each propagated signal, reversible accumulator means for accumulating said propagated and produced signals during said time interval, means for exciting said seconD transducer to propagate signals toward said first transducer for a second time interval equal to said first time interval, means responsive to each signal propagated toward said first transducer for producing said predetermined number of signals, and means for decrementing the contents of said accumulator once for each signal propagated and produced during said second time interval, whereby the residual contents of said accumulator means represents the relative speed of the object along said axis through the fluid.

Claim 3

The apparatus of claim 1, including means actuated following each of said second time intervals for indicating the contents of said accumulator.

Claim 4

The apparatus of claim 1, further comprising means for accumulating the residual contents of said accumulator over a sequence of said first and second time intervals to provide a measure of distance elapsed by the object through the fluid.

Claim 5

A marine speedometer, comprising a skeg mounted on the hull of a vessel beneath the waterline thereof and aligned parallel to the keel of the vessel, a pair of transducers mounted in spaced confronting relationship on said skeg and in alignment therewith, singaround circuit means connected to said transducers and responsive to a first applied signal for propagating a first series of signals from a first of said transducers toward the second at intervals determined by the propagation time of said signals from the first transducer to the second during said first applied signal, said singaround circuit means being responsive to a second applied signal for propagating a second series of signals from said second transducer toward said first transducer at intervals determined by the propagation time of said signals from the said second transducer to said first transducer during said second applied signal, means responsive to said first applied signal and said first propagation signals for generating a train of a predetermined number of signals following each first signal propagated between said transducers, means responsive to said second applied signal and said second propagated signals for generating a train of said predetermined number of signals following each second signal propagated between said transducers, means for alternately applying said first and said second signal to said singaround circuit means for equal time durations, and reversible accumulator means connected to said singaround circuit means and responsive to said first applied signal for registering the number of propagated and generated signals during said first applied signal, said accumulator means being responsive to said second applied signal for decrementing the contents of said accumulator means once for each propagated and generated signal during said second applied signal.

Claim 6

A marine speedometer, comprising a skeg mounted on the hull of a vessel beneath the waterline thereof and aligned parallel to the keel of the vessel, a pair of transducers mounted in spaced confronting relationship on said skeg and in alignment therewith, singaround circuit means connected to said transducers and responsive to a first applied signal for propagating a first series of signals from a first of said transducers toward the second at intervals determined by the propagation time of said signals from the first transducer to the second during said first applied signal, said singaround circuit means being responsive to a second applied signal for propagating a second series of signals from said second transducer toward said first transducer at intervals determined by the propagation time of said signals from the said second transducer to said first transducer during said second applied signal, means responsive to said first applied signal and said first propagation signals for generating a train of a predetermined number of signals following each first signal propagated between said transducers, means responsive to said second applied signal and said second propagated signals for generating a train of said predetermined number of signals following each second signal propagated between said transducers, means for alternately applying said first and said second signal to said singaround circuit means for equal time durations, and reversible accumulator means connected to said singaround circuit means and responsive to said first applied signal for registering the number of propagated and generated signals during said first applied signal, said accumulator means being responsive to said second applied signal for decrementing the contents of said accumulator means once for each propagated and generated signal during said second applied signal.

Claim 7

The apparatus of claim 4, further comprising a register, means actuated following each second signal for transferring the contents of said accumulator to said register, and indicating means coupled to said register for indicating the speed of the vessel in terms of the contents of said register.

Claim 8

The apparatus of claim 5, further comprising a second register, and means effective following the transfer of the contents of said accumulator to said first register to add the contents of said accumulator to said second register, thereby providing a measure of elapsed distance,

Claim 9

The apparatus of claim 6, in which said addiing means comprises a signal divider to cause the contents of said second register to represent the elapsed distance in predetermined units.

Claim 10

In combination with an object at least partially immersed in a fluid and an acoustic flowmeter mounted on said object, said flowmeter being of the type comprising a reversible accumulator, singaround transceiver means coupled to said accumulator for producing signals at a first rate determined by the rate of propagation of sonic signals through the fluid from a first Transducer on the object to a second transducer on the object and at a second rate determined by the rate of propagation of sonic signals from said second transducer to said first transducer, said signals being propagated for equal times in said opposite directions and added in the accumulator while propagated in one direction and subtracted from the accumulator while propagated in the opposite direction, that improvement comprising means for producing a train comprising an equal number of signals following each propagated signal and proceding the next, and means for adding or subtracting those produced signals following propagated signals to or from said accumulator during said equal times according as said propagated signals are added or subtracted, respectively whereby the contents of said accumulator following a pair of said equal times represents the relative velocity of said object in said fluid along the line between said transducers more accurately than would the difference between the signals actually propagated during said equal time intervals.

Claim 11

In combination with an object at least partially immersed in a fluid and an acoustic flowmeter mounted on said object, said flowmeter being of the type comprising a reversible accumulator, singaround transceiver means coupled to said accumulator for producing signals at a first rate determined by the rate of propagation of sonic signals through the fluid from a first Transducer on the object to a second transducer on the object and at a second rate determined by the rate of propagation of sonic signals from said second transducer to said first transducer, said signals being propagated for equal times in said opposite directions and added in the accumulator while propagated in one direction and subtracted from the accumulator while propagated in the opposite direction, that improvement comprising means for producing a train comprising an equal number of signals following each propagated signal and proceding the next, and means for adding or subtracting those produced signals following propagated signals to or from said accumulator during said equal times according as said propagated signals are added or subtracted, respectively whereby the contents of said accumulator following a pair of said equal times represents the relative velocity of said object in said fluid along the line between said transducers more accurately than would the difference between the signals actually propagated during said equal time intervals.

Claim 12

In combination with an acoustic flowmeter comprising a singaround circuit producing a first series of signals propagated at a first rate in a first direction in a fluid in which the flowmeter is at least partially immersed, each succeeding said signal being responsive to its preceding signal, and a second series of signals propagated at a second rate in a second sense in a direction opposite said first direction in said fluid, in which said first and second rates are determined by the relative velocity of the flowmeter in the fluid along a line parallel to said opposite directions, a relaxation oscillator responsive to each signal propagated through said medium to produce a signal train, a counter controlled by said signal train to disable said oscillator prior to the shortest time between propagated pulses, an accumulator, means for incrementing said accumulator for a first predetermined time in response to each of said first propagated signals and each signal produced by said oscillator during said first time, and means for decrementing said accumulator for a second time equal to said first time in response to each of said second propagated signals and each signal produced by said oscillator during said second time.

Claim 13

In combination with an acoustic flowmeter comprising a singaround circuit producing a first series of signals propagated at a first rate in a first direction in a fluid in which the flowmeter is at least partially immersed, each succeeding said signal being responsive to its preceding signal, and a second series of signals propagated at a second rate in a second sense in a direction opposite said first direction in said fluid, in which said first and second rates are determined by the relative velocity of the flowmeter in the fluid along a line parallel to said opposite directions, a relaxation oscillator responsive to each signal propagated through said medium to produce a signal train, a counter controlled by said signal train to disable said oscillator prior to the shortest time between propagated pulses, an accumulator, means for incrementing said accumulator for a first predetermined time in response to each of said first propagated signals and each signal produced by said oscillator during said first time, and means for decrementing said accumulator for a second time equal to said first time in response to each of said second propagated signals and each signal produced by said oscillator during said second time.

Claim 14

The apparatus of claim 9, further comprising a register, a speed indicator controlled by the contents of said register, and means for copying the contents of said accumulator into said register at the end of each second time.