Abstract: In an ultrasonic detection system that uses frequency-modulation or phase-modulation coding to distinguish emitted bursts from multiple transducers, a receiver associated with a transducer uses peak search, peak buffer, and peak rank stages in one or more receiver signal processing paths to identify valid received ultrasonic signal envelope peaks in correlator outputs. The peak rank stage can support different modes respectively designed to handle one code, two or more codes, or two or more codes with support for Doppler frequency shift detection. Valid peak information (e.g., amplitude and time) can be reported to a central controller and/or stored locally in a fusion stage to generate more intelligent information for targets or obstacles using peaks from multiple bursts.

Abstract: An electronic guidance system for visually impaired persons includes a sensor for detecting the proximity and orientation of an approaching object and a microprocessor that is programmed to translate signals from the sensor into audible signals that are projected by directionally oriented speaker components into the user's ears. The system enables the user to determine the proximity, location, movement and identity of the approaching object.

Abstract: A beam configuration method and a device are provided and can resolve problems that a signal gain is a relatively low and utilization of an antenna array unit is low in a process of implementing omnidirectional coverage of a millimeter wave. A specific solution is as follows: determining whether an included angle between a ray that is perpendicular to a first plane and that extends outward from an electronic device and a ray pointing from the electronic device to a peer device is less than or equal to a preset angle, and when the included angle between the ray that is perpendicular to the first plane and that extends outward from the electronic device and the ray pointing from the electronic device to the peer device is less than or equal to the preset angle, performing end-fire state configuration on antenna array units in the first plane.

Abstract: An intravascular imaging system includes a transducer capable of generating raw data representative of the structure of a patient's vasculature. The system includes an imaging engine for receiving the raw data and generating enhanced data for presentation to a user. The imaging engine includes a coherence filter, an envelope detection module having one or more envelope detectors, and a spatial filter for processing data in various stages. Such stages of processing in the imaging engine act to reduce high frequency noise, generate low frequency data, reduce low frequency noise, and display low frequency data with an improved signal-to-noise ratio. The system can include an image generator for generating an image based on enhanced data and a display for displaying the generated image.

Abstract: A technology is provided for determining a range of a target using multiple analog ramps. A slow ramp voltage level can be identified that indicates an approximate arrival time for a light pulse to be received as a target reflection after propagating towards the target. A slope number associated with the slow ramp voltage level can be identified, wherein the slope number is an integer ranging from 0 to N. An adjusted slope number can be calculated using the slope number and fast ramp information. A coarse range and a fine range of the target can be determined using the adjusted slope number. The range of the target can be calculated by adding the coarse range and the fine range.

Abstract: A method is provided for generating an alarm signal in a vehicle for indicating that the vehicle is in the proximity of an object includes detecting a degree of proximity to the object, calculating a value of the distance (d) between the vehicle and the object, generating the alarm signal at least as an audio signal when the distance (d) is less than a predetermined first threshold value (d1), and generating the alarm signal in the form of a sequence of signal stages as the distance (d) decreases. A system is also provided for generating an alarm signal in a vehicle.

Abstract: A method is disclosed for improving performance of a Sodar system adapted to locate discontinuities in the atmosphere by transmitting pulse compression signals such as plural acoustic chirps. The method comprises transmitting the acoustic chirps, receiving acoustic echoes of the chirps, and processing the acoustic echoes to provide an indication of the discontinuities, wherein the processing includes correcting range or resolution error associated with the acoustic echoes.

Abstract: A capacitive coupling based proximity sensor is disclosed. In some embodiments, a sensor embedded in a mobile device comprises a transmitter configured to transmit a transmit signal and a receiver configured to receive a receive signal via capacitive coupling between the receiver and the transmitter as well as a circuit configured to detect human proximity to the mobile device in the event that the receive signal does not sufficiently match the transmit signal and configured to generate an output signal indicating human proximity to the mobile device that is employed to facilitate an appropriate response.

Abstract: A system and a method for generating a three-dimensional image of a rock formation, compressional velocity VP, shear velocity VS and velocity ratio VP/VS of a rock formation are provided. A first acoustic signal includes a first plurality of pulses. A second acoustic signal from a second source includes a second plurality of pulses. A detected signal returning to the borehole includes a signal generated by a non-linear mixing process from the first and second acoustic signals in a non-linear mixing zone within an intersection volume. The received signal is processed to extract the signal over noise and/or signals resulting from linear interaction and the three dimensional image of is generated.

Abstract: A method and apparatus for an aircraft location system comprising an aircraft structure and a number of acoustic reflectors associated with the aircraft structure. The number of acoustic reflectors is configured to generate first sound signals in response to receiving second sound signals.

Abstract: A human echolocation system emits toward a target a series of sound pulses beginning at a low frequency and progressing stepwise to a high frequency. Echoes of the pulses enable the user to estimate location, distance and dimensions of the target. Target location and distance are estimated based on a stretched echo delay, while target dimensions are estimated based on a musical pitch corresponding to the echo frequency.

Abstract: A sonar array for forming multiple transmit and/or receive acoustic beams by a frequency beamforming technique. In frequency division beamforming, beam steering direction is made a function of frequency by driving (receiving) each element of a uniformly spaced line array by a signal which leads or lags its nearest neighbor by a fixed phase shift, &Dgr;&phgr;. This permits scanning a transmit and/or receive beam through a range of angles by changing its frequency. The same principle can be used to form multiple simultaneous transmit and/or receive beams. This is accomplished by transmitting a wide bandwidth signal and receiving the echoes through a spectrum analyzer. Each frequency bin of the spectrum analyzer then corresponds to a beam pointing in its own unique direction. Advantages of such a sonar system include improved cost, weight, and size versus performance for a variety of systems including ahead looking sonars and bottom mapping sonars.

Abstract: The present invention relates to radars and sonars, and more particularly to a synthetic-band technique of pulse compression making it possible to reach a very high distance resolution. Synthetic band consists in transmitting a waveform pattern consisting of a string of N coherent elementary pulses, linearly frequency-modulated, following one another at a recurrence frequency F.sub.r, of rectangular frequency spectra of elementary band B and of stepped carrier frequencies such that their frequency spectra will link up exactly one ahead of another to form a global spectrum of width N.times.B. On reception, the frequency spectra of the signals received in return for the N elementary pulses of a pattern are extracted by calculation, translated and juxtaposed so as to reconstruct a global frequency spectrum of width N.times.B and then compressed. Pulse compression is thus obtained which is equivalent to that which would result from the transmission of a waveform having a single pulse of frequency band N.times.

Abstract: A personal object or obstacle detector apparatus with enhanced stereo imaging capability includes a sonar system having dual receivers with field lobes positioned based on psychoacoustic considerations such as interaural intensity difference (IID) and interaural time difference (ITD). Receiver field pattern shapes and directions are selected to match the natural IID and ITD associated with human hearing. In one embodiment, dual receivers are used with a common transmitter while another embodiment utilizes two transmitter/receiver pairs with the transmitter and receiver collocated.

Abstract: In a distance measurement to an object, the distance measurement operating according to the FMCW principle, a linear frequency-modulated signal is transmitted and mixed with the signal reflected back from the object, generating a demodulation signal with a frequency proportional to the distance. To determine the distance, at least one estimation signal with an assumed frequency and a variable phase is generated and an estimation error is determined by comparison of the transmitted signal and the estimation signal. The phase of the estimation signal is adaptively varied for the purpose of an error reduction and the frequency of the estimation signal is corrected corresponding to the variation of the phase over time, the distance being determined from the frequency corrected in this manner.

Abstract: A personal object or obstacle detector apparatus comprises a continuous transmission frequency modulation (CTFM) ranging system and an audio output device. The CTFM ranging system transmits a frequency-swept pressure wave, receives a reflected frequency-swept pressure wave from at least one object, and forms an audio signal based upon a frequency difference between the frequency-swept pressure wave and the reflected frequency-swept pressure wave the audio signal having an amplitude dependent upon size of the object. The audio output device produces an acoustic pressure wave in dependence upon the audio signal. In a preferred embodiment, the acoustic pressure wave contains separate tones for each of the objects detected, wherein each tone has a pitch dependent upon the distance from the CTFM ranging system to the corresponding object. Another embodiment utilizes a pair of CTFM ranging systems to produce a stereo auditory map of objects and obstacles.

Abstract: A pulse compression signal processor (10) for a laser radar system which utilizes substantially identical negative slope SAW matched filters (30,44) for compressing both the up and down chirps of a bi-directional echo signal (14). The signal processor (10) receives the echo (14) and splits it into two signals (16, 18) for processing by separate negative slope SAW matched filters (30, 44).

Abstract: False target (reverberation, clutter, etc.) detection is suppressed in an echo ranging system (sonar or radar) in which target velocity and range are measured using a composite Doppler invariant-like signal having at least two segments, such as are present in a "rooftop" or "vee" HFM signal, such composite signal having an ambiguity function with two or more ridge lines of different slopes that intersect along the zero-velocity time axis. A bank of matched filters provides a distribution of outputs which has an ambiguity function-like character with intersecting pairs of ridge lines, the intersecting points of said pairs characterizing the range and velocity of the echo returns. This distribution is adjusted so that the intersecting ridge lines of each pair have equal and opposite slopes with respect to the time axis. In particular, fixed reverberators, which would have ridge lines intersecting on the zero-velocity time axis, would be symmetrical about this axis.

Abstract: Target velocity and range are measured with high resolution in an echo ranging system (sonar or radar) using composite Doppler invariant signals consisting of at least two segments, such as "rooftop" or "vee" HFM signals, such composite signals having ambiguity functions that intersect along the zero-velocity time axis with ridge lines slanted in different directions. A single correlator is used for each segment wherein returns from the target are correlated with replicas of each segment of the composite signal to separately transform the Doppler frequency shifts of the target return into outputs whose time relationship provides a frame of reference for high resolution measurement of the velocity of the target. The time relationship measurement is implemented by a set of tapped delay lines and coherent summers which output a coherent correlation-like detection peak in a bin which corresponds to the target's velocity.

Abstract: The difficulty of making Doppler shift velocity measurements in a chirp pulse echo ranging system is overcome by employing a pulse frequency compression filter, suitably a SAW compressor 45, having individual outputs 64, 65, 66, 67 respectively relating to adjacent contiguous frequency bands A, B, C, D, (FIG. 3) each having a bandwidth approximately equal to the chirp frequency swing. Signal detection and processing means 70 senses the occurrence of a compressed pulse on any of the outputs and measures the amplitudes of signals on all the outputs. A computer then computes the Doppler shift from the amplitude ratio of the sensed signals to adjacent frequency bands, determines the target velocity therefrom and uses the result also to correct the range measured by the counter 5.

Abstract: This invention relates to contactless proximity sensing transducers and more particularly concerns a single crystal ultrasonic interferometer comprised of a piezoelectric crystal attached to a Pyrex plate for acoustic impedance matching purposes. When driven at the crystal's resonant frequency, the electrical impedance of the crystal becomes sensitive to the input acoustical impedance of the interferometric path length between the crystal and the target object. By monitoring the crystal impedance at a fixed frequency as target position is varied, the sensor is capable of determining the incremental displacement of the moving target. By monitoring the crystal impedance at a fixed target position as the driving frequency is varied, the sensor is capable of determining the absolute proximity of the target. The geometry of the piezoelectric crystal and the Pyrex plate are used to affect the resolution and frequency response of the sensor.

Abstract: A laser radar system wherein a beam of continuous wave (CW) electromagnetic energy is generated with frequency modulation (FM) and amplitude modulation (AM) being imposed thereon to produce an amplitude and frequency modulated, continuous wave beam of energy. The AM-FM CW beam is transmitted toward a selected target, portions of the transmitted beam being reflected by the target and received along with portions of the transmitted beam reflected by unselected targets and atmospheric clutter. A first signal is produced in response to the frequency modulation on the received beam portions reflected by the selected target, such first signal representing the approximate range of the selected target and substantially resolving the selected target from unselected targets and atmospheric clutter and having a relatively long ambiguous range interval.

Abstract: An ultrasonic wave signal having its frequency varied continuously is transmitted from an ultrasonic wave transmitter toward a moving body. The wave reflected from the moving body is received by an ultrasonic wave receiver, and the resulting signal is frequency-demodulated to obtain a signal representing a frequency variation. A signal representing the feature of the moving body is produced with use of a signal representing the frequency variation of the transmitted ultrasonic wave and the signal representing the frequency variation of the received ultrasonic wave.

Abstract: The receiver (3') of a laser range finder operating on the pulse propagation and including a transmitter unit (1) and a first receiver unit (2) is sampled by a spike pulse (5) derived from the transmitter pulse in such a way as to produce a low-frequency representation (10). The non-linearity of the phase modulation of this spike pulse, which is detrimental in very accurate measurements taken over long distances, is eliminated in that the oscillations of high-frequency oscillator (8) are supplied to a second receiver unit (2') in which they are scanned by the same spike pulse (5) and are then also suitably transformed into a low-frequency representation (10'). A counter (12) then counts the low-frequency zero-passages of the oscillator, beginning with the onset of the low-frequency cycle, thereby eliminating all errors (FIG. 1).

Abstract: The data selection circuit includes a multiplexer circuit which receives a plurality of inputs and individually connects each of the inputs to an output line. The multiplexer is sequenced by signals from a timing circuit which causes inputs having a higher signal level to be connected to the multiplexer output for a greater length of time. The data selection circuit is particularly suitable for enhancing the image on a CRT of a continuous tone frequency modulated sonar system.

Abstract: A continuous transmission FM sonar avoids target ambiguities while utiliz the entire transmitted bandwidth for echo analysis. The sonar is characterized by digital generation of direct and quadrature versions of the transmitted frequency sweep, and balanced modulators responsive thereto to effect complex demodulation of the returned signals prior to analysis, as by a fast fourier transform frequency analyzer for target detection.

Abstract: A device for producing a varying frequency sine wave synthesized so that frequency is swept linearly with time for use in a continuous transmission FM sonar. A crystal clock, divider and a 16 bit digital output sweep counter produce 2.sup.16 counts for each sweep period T.sub.s. The 2.sup.16 counts are applied to a 16 bit digital to analog converter to provide a highly linear voltage ramp (the smoothed result of 2.sup.16 steps). The ramp is converted to a proportional frequency which is applied to a 5 bit digital counter to access a read only memory programmed to provide a digital output representing points along a sine wave. The memory output is applied to a digital to analog converter to produce a voltage output that is a 32 stepped approximation of a sinewave at a frequency which increases betweeen f.sub.1 and f.sub.2 with the linearity of the ramp voltage. A filter smoothes the output.

Abstract: A method of and apparatus for locating an object by stress wave energy reflection in which the wave energy is transmitted as a beam by transmitting transducer elements, and is scanned through successive sectors of a field of view by imposing differential transmission delays on transmitting signals fed to the elements by means of a delay line. Indicator signals are developed in receiving channels connected respectively to receiving transducers providing binaural characteristics, and transducer providing monaural characteristics but collectively covering the field. An indicator means comprises any, or any combination, of audible means, visual means or tactile means the two latter providing coordinate displays.

Abstract: A method of locating an object by wave energy reflection and an apparatus therefor in which receiving outer transducers provide directional receptivities represented by polar lobes diverging on opposite sides of a reference axis and an inner receiving transducer provide a directional receptivity represented by a narrower polar lobe centered on the reference axis. The signals received from the outer transducers are operated upon in channels of the receiver to modulate them with a frequency swept local signal derived from the transmitted signal and develop indicator signals of difference frequency between the transmitted and received frequencies and which represent the range of the object. The outer signals are displayed binaurally, to enable the user to achieve firstly approximate directional sensing by binaural effect, and thereafter more accurate directional sensing by the use of signals developed in a central channel and derived from the inner transducer or outer transducers simulating an inner transducer.

Abstract: A method and apparatus is disclosed for use of a linear frequency chirp in a transmitter/receiver (14/16) having a correlator to synthesize a narrow beamwidth pattern from otherwise broadbeam transducers when there is relative velocity between the transmitter/receiver (14/16) and the target. The chirp is so produced in a generator (20) in bandwidth, B, and time, T, as to produce a time-bandwidth product, TB, that is increased for a narrower angle. A replica of the chirp produced in a generator (26) is time delayed and Doppler shifted for use as a reference in receiver (16) for correlation of received chirps from targets. This reference is Doppler shifted to select targets preferentially, thereby to not only synthesize a narrow beam but also aim the beam in azimuth and elevation.

Abstract: A method and apparatus is disclosed for determining the manner by which an initial injection of wave energy is modified by a medium under test using a time delay spectrometer (TDS) and a fast Fourier transform (FFT). A switch allows either the time delay spectrum or an energy-time curve to be displayed. A differentiator at the input of the FFT corrects for inverse square loss of energy through the medium, i.e., compensates for spherical expansion of energy. Different arrangements of the TDS adapt the system to a medium having variable time delay, or adapt the system for measurement of harmonic distortion through the medium.

Abstract: A propeller modulation enhancement and display system which suppresses hull cho and displays propeller modulation of a return sonar signal in real time. The real-time operation is obtained through the use of a multichannel frequency spectrum analyzer having a plurality of narrow bandpass filters covering the frequency of interest. Suppression of the hull echo is obtained through the use of a narrow band-reject filter having a variable center frequency. The filter precedes the multichannel frequency spectrum analyzer.

Abstract: A target location system comprising a signal transmitter including a pair of signal transmitter transducers arranged in spaced apart relationship and means for driving the transducers with transmitter pulse signals at the frequencies Fo and Fo+Fb respectively which are arranged to increase progressively in frequency during each pulse to Fo+.DELTA.f and Fo+Fb+.DELTA.f respectively where .DELTA.f is equal to or less than Fb, and an echo signal receiver comprising receiving transducer means feeding a filter bank, the filter bank comprising a plurality of filters which cover in aggregate a predetermined frequency band, each filter being adapted to cover one slot or section of the band whereby the bearing of a target from which an echo signal of a transmitter pulse signal is received, is indicated in accordance with the slot or slots in which the echo signal is received.

Abstract: A target location system comprising a signal transmitter arrangement for transmitting pulses the frequency of which increase progressively during each pulse period from a frequency f to a frequency f+.DELTA.

Abstract: A method of and apparatus for locating an object by stress wave energy reflection in which the wave energy is transmitted as a beam by transmitting transducer elements, and is scanned through successive sectors of a field of view by imposing differential transmission delays on transmitting signals fed to the elements by means of a delay line. Indicator signals are developed in receiving channels connected respectively to receiving transducers providing binaural characteristics, and transducer providing monaural characteristics but collectively covering the field. An indicator means comprises any, or any combination, of audible means, visual means or tactile means the two latter providing coordinate displays.

Abstract: Linear frequency modulation having a large time-bandwidth product and an remely linear frequency versus time waveform, is provided by a feedback technique utilizing a linear ramp voltage generator whose output is summed with a correction voltage to drive a voltage controlled oscillator to output the LFM waveform. Part of the LFM waveform is fed back through a digital discriminator for error signal generation and comparison with a preset value associated with the output slope linearity, thus yielding the basis for generating the correction voltage.

Abstract: A sonar array for forming multiple transmit and/or receive acoustic beams by a frequency beamforming technique. In frequency division beamforming, beam steering direction is made a function of frequency by driving (receiving) each element of a uniformly spaced line array by a signal which leads or lags its nearest neighbor by a fixed phase shift, ??. This permits scanning a transmit and/or receive beam through a range of angles by changing its frequency. The same principle can be used to form multiple simultaneous transmit and/or receive beams. This is accomplished by transmitting a wide bandwidth signal and receiving the echoes through a spectrum analyzer. Each frequency bin of the spectrum analyzer then corresponds to a beam pointing in its own unique direction. Advantages of such a sonar system include improved cost, weight, and size versus performance for a variety of systems including ahead looking sonars and bottom mapping sonars.