Abstract: From a first aspect this invention provides a missing pulse detector for determining the true termination time of a sequence of pulses in a signal of an assumed predetermined length having a rising edge and a trailing edge which may include pulses which do not reach a predetermined threshold, the detector including a counter connected to count pulses exceeding said threshold, up to a predetermined number, an oscillator for producing pulses at twice the frequency of the pulses in the signal and an enabling circuit for allowing pulses from the oscillator to pass to the counter only after the termination of a sequence of threshold-exceeding pulses from the signal.

Abstract: The device comprises at least two ultrasonic transducers emitting focused radiation and a circuit making it possible to measure the difference between the sampled signals supplied by these two transducers. This difference is cancelled out when the probe faces the object.Application to metrology and the position control of objects.

Abstract: An apparatus for detecting the position of an object with an ultrasonic wave includes a timing control circuit generating first and second timing signal trains, the interval of the first timing signal trains being set to be shorter than that of the second; an ultrasonic wave pulse generator circuit generating first and second ultrasonic wave pulses in synchronism with the first and second timing signal trains, the first ultrasonic wave pulses covering a short distance range to the object and the second ultrasonic wave pulses covering a long distance range to the object, the width of the first ultrasonic wave pulse being set to be shorter than that of the second. An ultrasonic wave pulse transmitter transmits alternately the first and second ultrasonic wave pulses; a receiver receives the reflected first and second ultrasonic wave pulses from the object; and a discriminator circuit discriminates the reflected first and second ultrasonic wave pulses from the receiver.

Abstract: A method for synthesizing arbitrary broadband signals for a parametric ar which computes the input waveform needed to a parametric array source to obtain a received signal of a prescribed waveform. The method uses Fourier transform and the inverse transform of digitized received signal in order to make computation in either the frequency domain or the time domain depending upon the computational simplicity in a particular domain. The method uses a iterative process to obtain the received signal very close to the received signal of the desired waveform.

Abstract: A depthsounder for selectively measuring either bottom depth or the depth of any fish located beneath a vessel. When operating in a depth mode, the depthsounder automatically adjusts the gain of its receiver to minimize interference and provide a filtered display of bottom depth. When operating in a fish finding mode, the depthsounder likewise automatically adjusts the gain of its receiver to minimize interference in its detection of fish. In addition, the depthsounder suitably processes any return pulses to distinguish those produced by fish from those produced by other objects in the water. When fish are detected, the depthsounder provides a visual display of their depth and an aural alarm whose repetition rate is proportional to the number and size of the fish.

Abstract: An acoustic distance measuring system for detecting a small change in position of a remote object and changing the state of a relay. An acoustic transmitter and receiver are connected by an amplifier circuit which is induced into oscillation when a portion of the transmitted acoustic signal is reflected by a remote surface back to the receiver, forming an external feedback path, said oscillations occurring only in alternate half wavelengths of feedback path length, in which the reflected waves are generally in phase with the transmitted waves. A detector circuit responsive to the amplifier oscillations provides an output which is used to change the state of a relay.

Abstract: A frequency control system with a phase-locked loop for automatically adjusting the frequency of an alternating signal and an external signal derived coherently therefrom to the variant zero phase-shift frequency of a phase shifter adapted to receive the external signal, the control system comprising: a phase shifter responsive to the external signal for introducing a frequency sensitive bipolar phase-shift to the external signal to produce a phase shifted external signal thereat, the phase shifter introducing zero phase-shift at a drift-prone frequency, f.sub.o ; an alternating signal source for generating the alternating signal of adjustable frequency covering a range of frequencies including frequency, f.sub.

Abstract: A distance R to be measured is derived by measuring the spacing x.sub.m between a fixed transmitter Tx and a movable receiver Rx, and comparing this with the reference spacing x.sub.ref between a fixed transmitter Tx' and receiver Rx. Each spacing is measured by passing a large number of pulses sequentially from receiver to transmitter through a coupling medium, the receipt of one pulse triggering transmission of the next. The spacing is derived from the time T taken to pass n pulses; preferably n is fixed and T is measured.

Abstract: A device for the transit time measurement of electric, electromagnetic or oustic signals, particularly supersonic signals, of at least one predetermined frequency range, having a signal transmitter for the sending of measurement signals to an object and a signal receiver for the receiving of the measurement signals reflected by the object which have a substantially predetermined frequency corresponding to the frequency of the other signals sent and having a time measuring device for determining the transit time of the measurement signals between the signal transmitter and/or receiver and an object, from which the distance of the object from the signal transmitter and/or the signal receiver can be derived. A signal generator is provided both at least to trigger the signal transmitter and to control the signal receiver, and a filter stage for the tuning of the signal receiver in accordance with the reception frequency and for filtering out external frequencies is connected with the signal generator.

Abstract: A digital sonar system including a redundant receiver channel is arranged to operate substantially simultaneously in both F.M. and C.W. modes. Upon failure of one receiver channel the system reverts to a single mode or alternate modes on alternate cycles.

Abstract: Probe method and means are disclosed for guiding and positioning a robot-actuated tool, such as a gripper or a welding head, through at least one transceiver for generating and sensing focused shockwaves, the probe being associated with the tool for relative movement with respect to the object or objects being sensed, without physically contacting the same.

Abstract: An echo tracker/range finder or altimeter in which the pulse repetition frequency (PFR) of a predetermined plurality of transmitted pulses is adjusted so that echo pulses received from a reflecting object are positioned between transmitted pulses and divide their interpulse time interval into two time intervals having a predetermined ratio with respect to each other. The thus-adjusted PRF is related to the range of the reflecting object. More specifically, the invention provides a means whereby the arrival time of a plurality of echo pulses is defined as the time at which a composite echo pulse formed of a sum of the individual echo pulses has the highest amplitude. This arrival time is determined by dividing an interpulse time interval between adjacent transmitted pulses into a predetermined plurality of corresponding time increments.

Abstract: Flow of viscous molten metal (12) to thin sections (48) of mold cavities (14) is difficult to attain thus resulting in inferior molded products. This problem is solved herein by generating waves (20) in the molten metal (12), sensing the waves (20) in the molten metal (12) at a thin section (48) of the mold cavity (14) spaced from the generating position of the waves (20), and controlling the generating responsive to the waves (20) sensed. Basically, a control circuit (56) increases the amplitude, and/or changes the frequency, of the waves (20) generated, if the waves (20) sensed are not sufficiently strong. The invention is useful for flowing other liquids besides molten metal in other cavities than in molds, although this is its prime contemplated use.

Abstract: A navigation aid for determining berthing data comprises distance detecting units embodying sonar transducers which are spaced apart along the length of a jetty a short distance behind the berthing line. The units are operative to provide signals indicative of the distance from the berthing line of correspondingly spaced sections of the ship, and a microcomputer selects two out of three of these signals and processes them to determine the distance from the berthing line of nominal bow and stern sections of the ship, the nominal measuring points being different from the actual measuring points at which the transducers are positioned. The microcomputer also processes the selected signals to determine the velocity of the bow and stern sections relative to the berthing line, and controls a jetty display of the determined distance and velocity data in addition to local and remote indications/recordal thereof.

Abstract: 1.

Abstract: An ultrasonic centering apparatus, wherein it comprises at least one ultrasonic transducer placed within an enclosure, said transducer transmitting at least one ultrasonic wave, means for collecting the different ultrasonic echos from the walls of said enclosure, means for measuring the time gap separating the reception of the different echos and means for displacing the transducer or transducers until the different echos are received at the same time by said echo receiving means.A particular application of the invention is to the centering of inspection equipment in the tubes of nuclear reactor vessels.