Abstract: A range control system positioned within a stationary housing comprising: a pulse oscillator for providing a clock signal; and a transmitter receiver circuit that directionally transmits an acoustic pulse signal to a target and receives an echo from the target to provide an amplified echo signal. A timing circuit means is included for providing a range gate signal characterized to start with each clock signal and to have a predetermined duration characterized to provide a time for the acoustic pulse to travel to the target and for the echo to return from the target. An alarm signal is provided to indicate that an echo signal is being received prior to the termination of the range gate signal. A ring blanking gate signal source provides a ring blanking gate signal commencing with each clock signal and having a duration longer than the tailoff ringing of the acoustic pulse. A diode clamp is coupled to the transducer drive circuit echo signal output.

Abstract: A self-calibrating ultrasonic distance sensing method and apparatus are disclosed in which a transducer periodically transmits a pair of bursts of acoustic energy along an acoustic path toward a target object. Echoes of the first acoustic burst in the burst pairs from a reference target at a known distance from the transducer are used for calibration purposes, and echoes of the second acoustic bursts in the pairs are used to determine distance to the target object.

Abstract: An environmental interference detection device, consisting of IC.sub.4, D.sub.5, C.sub.13, R.sub.11, Q.sub.1 and a display unit, in which IC.sub.4 is used for signal phase inversion, D.sub.5 is used for filtering out the negative half wave of the signal, R.sub.11, C.sub.13 form a time delay circuit used to eliminate the sudden outbreak type of signal, and Q.sub.1 is used to drive the display unit. Users of an audio frequency detection device can use the indication of the display unit to adjust the sensitivity of the audio frequency detection device to a proper setting so as to efficiently utilize its monitoring function.

Abstract: An ultrasonic distance sensing method and apparatus are disclosed in which a transducer periodically transmits a pair of bursts of acoustic energy along an acoustic path toward a target object, an echo of the first acoustic burst in each burst pair is used to establish a peak reference level, and an echo of the second burst in each pair is used to determine distance to the target object only if its level exceeds a predetermined fraction of the peak reference level.

Abstract: An ultra-sonic sensor includes a driver circuit outputting a high-frequency driver signal which orders a transmitter to transmit ultra-sonic waves toward a target object. The driver circuit also sends the driver signal to a receiver. The driver signal is superimposed on a receiver signal. The receiver differentiates the receiver signal and compares the differentiated receiver signal level to a threshold level to detect reception of the reflected ultra-sonic wave. The receiver also detects when the transmitter is actively transmitting the ultra-sonic waves toward the object and disables the aforementioned comparison at such times. Accordingly, by comparing the differentiated receiver signal level with the threshold, the influence directly transmitted ultra-sonic waves on detection of the reflected ultra-sonic wave is successfully avoided.

Abstract: The sonic or ultrasonic distance measuring device used for example to measure the filling level in a container comprises an electroacoustic transducer which operates alternately as transmission transducer for the transmission of sonic or ultrasonic pulses and as reception transducer for the reception of the reflected echo pulses. Connected to the transducer is a signal processing circuit which includes an amplifier with controllable gain and a threshold value discriminator. A gain control circuit controls the gain of the amplifier during a predetermined period after the start of each transmission pulse in accordance with a stored function which is fixed in accordance with the dying-down behaviour of the transducer so that the electrical signals originating from the dying-down of the transducer after amplification are smaller than the threshold value of the threshold value discriminator but are as close as possible to said threshold value.

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: An improved method and apparatus for measuring the length of an open pipe includes a sound transducer placed in spaced open air communication with the interior of the pipe at a selected end. A logic circuit is employed with the transducer for producing a square wave sound pulse that is directed at the pipe's selected end. An oscillator provides an ambient temperature modified count in accordance with the time required for the pulse to travel the length of the pipe and return. For compensating for error tending to be introduced because of the spacing of the impedance reflective surface at the far end of the pipe, a standoff device establishes such a distance between the transducer and the selected end of the pipe as to effect an adjustment in the duration of the oscillator count that corrects for the error.

Abstract: In a radar or sonar system wherein the detection of a target is to be accomplished with a constant false alarm rate (CFAR), a circuit is provided for adjusting the input to a comparator which compares the received echo signals against the value of a threshold in order to detect targets of interest. The mean value of the background noise is subtracted from the signal, and the resulting difference is divided by the square root of the variance of background noise. The use of the variance compensates for sweep-to-sweep correlation and non-stationarity (in the statistical sense) as is found in clutter so that the clutter, upon the customary sweep-to-sweep integration of the signal, does not tend to introduce a false echo.

Abstract: A well logging method and apparatus for detecting the first arrival of an acoustic wave in a logging signal under adverse signal conditions. The received acoustic signal is amplified at a fixed gain until clipped at the largest amplitude throughout the logging procedure. This amplified signal is converted RMS to DC level signal and stored in sample and hold means for a period shortly before first arrival of the acoustic wave. The continuing DC level signal and the stored DC level signal are compared to produce a comparator output DC signal when the continuing DC signal has a certain increased magnitude. This certain increased magnitude is used to generate a pulse of given magnitude and duration that is especially suitable in digital data systems.

Abstract: A sonar device for use on a boat to indicate the depth of water on a digital display, including a transducer positioned in the water to transmit bursts of sound energy and for receiving echo energy reflected from the bottom, at least one variable gain receiver stage for amplifying the echo signals received by the transducer, a microprocessor for processing the amplified received signals to supply appropriate control signals to the digital display to indicate depth as a function of time required to receive echo signals, a means of controlling the gain of the receiver stage including a means with the microprocessor of supplying a plurality of paralleled output digital signals indicative of the required gain, means for converting the digital signal output to an analog gain control signal, and circuit means for applying the voltage gain control signal to the sonar receiver.

Abstract: A well-logging method and apparatus in which a fast real time portion of a logging signal is sequentially sampled at discrete times. These sampled segments are stored and then are clocked out of storage over an expanded time period.The rms amplitude portion of the logging signal occurring prior to the compression wave part of the logging signal (the nominal noise level) may be used for AGC regulation of an amplifier which amplifies the time-expanded output.A similar development of an rms value can be used for establishing a threshold level for a peak detector, which level is set slightly higher than such rms value. The first three successive samples greater than the threshold level detected by the detector are presumed to be the first three samples of the compression wave. This presumed compression wave is recorded and convolved against the expanded-time digital form of the logging signal to locate the compression wave in a second received signal and, later, the similarly appearing "shear" wave.

Abstract: A bistatic, Doppler sonar that having a plurality of receiver channels det intrusion in an insonified water zone processes return signals in a plurality of discrete up Doppler and down Doppler frequencies to effect short and long term averaging of return energy and short and long term averaging of return energy slope prior to sampling and comparison to generate a multiple bit binary word that is periodically updated and read out in parallel form to detection logic. The detection logic utilizes parallel sets of shift register memories and comparators to detect when rates of occurrence of energy, slope, and stroke conditions exceed predetermined rates, and utilizes a plurality of levels of coincidence gates to detect predetermined combinations of such conditions that will produce an alarm initiating signal.

Abstract: An oscillator generates a fixed frequency ultrasonic output signal. After wer amplification this signal drives a transmitting transducer which projects an ultrasonic beam into water. Reflected signals are received by a receiving transducer and AGC preamplified. A chopper multiplies the received signal with the transmitted signal and generates an output signal if a target exists. To determine whether the target is a swimmer, this output signal is band pass filtered and amplified and then fed both to an automatic alarm and to a set of headphones. A human operator listening to the headphone output classifies the target and determines exact bearing.

Abstract: There is described a digital sonar receiver having a novel beamformer, own doppler nullifier (O.D.N.), and adaptive time varied gain controller. The beamformer interrogates a multi-element transducer by utilizing an interleaved sampling scheme which samples the elements in the transducer array sequentially, in such a fashion that continuous, uniformly spaced samples are obtained. The samples are subsequently converted into digital format, weighed and summed. The O.D.N. eliminates the own ship's doppler effect on the beam output signal resulting in a half beam output signal representative of the target doppler. The O.D.N. offsets the frequency of the beam output signal and a digital generated signal representative of the own ship's doppler. The O.D.N. multiplies these two offsetted signals resulting in a signal lying in each of the sum and difference frequency bands for which the signal lying in the difference frequency band corresponds to the target doppler.

Abstract: An improved echo ranging system is disclosed which features improved circuitry for discrimination of received reflected pulses from noise. Discrimination is performed by comparison of the input pulses to a time-varying threshold voltage wherein the threshold function varies in accordance with the predicted attenuation of the transmitted echo signal over its path. In this way, variable gain elements used to amplify the received signal prior to comparison it with a fixed threshold height can be eliminated, thus rendering the circuitry less complicated, expensive, and calibration free.

Abstract: An echo-sounding receiver circuit comprising first and second receiver channels and an AND gate enabled by simultaneous outputs from both receiver channels is disclosed. The first receiver channel includes an echo stacking circuit, an echo selection circuit, and a tracking window circuit for establishing a measuring range or window whose timing is determined in part by detection of the first primary target echo in a sounding period and whose duration is established by the tracking window circuit. The second receiver channel includes a tracking threshold circuit and a second echo selection circuit for detecting the first echo that exceeds an amplitude determined by the amplitude of the preceding primary target echo. Upon detection of a primary echo by the second channel during the window established by the first channel, the AND gate supplies an output signal to a recording instrument or other utilization device.

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Abstract: An ultrasonic filling position limit switch having disposed in the container at the full level thereof, at least one ultrasonic transducer for sending out ultrasonic pulses and for receiving echo pulses reflected off the opposite container wall. An amplifier of the electric output signals of the transducer is connected to a threshold limit switch which provides an output signal when the amplifier output signal exceeds a predetermined threshold value. The amplifier output is fed back to an amplifier control input by means of an amplifier control circuit which seeks to maintain the amplifier output signal at an adjustable constant nominal value. A control device blocks the control circuit for the duration of time in each sending period required for the sending out of the ultrasonic sending pulses and for receiving the echo pulses.