Abstract: A method and apparatus for classifying objects in images utilize means for selecting portions of those images which contain objects and means for classifying those objects based upon parameters of the selected portions, which parameters are useful for classifying the objects. The selecting means preferably is a shadow and highlight detector, a statistical window detector and a neural network window detector whose output is combined in a combined cuer. The parameters are determined from the greylevels and positions of pixels using one or more modules which perform certain mathematical operations on this data. Such parameters include edge parameters, smoothness, clutter, presence and characteristics of highlights and shadows, and texture. The invention is particularly useful for classifying objects in sonar images as natural or man-made.

Abstract: A transmit beamformer includes multiple transducers, each responsive to a respective transmit waveform to produce a respective transducer waveform. A transmit waveform generator generates the transmit waveforms, and the transmit waveforms each include multiple frequency components. Progressively higher frequency components of the transmit waveforms are timed to cause corresponding progressively higher frequency components of the transducer waveforms to focus along a line at progressively shorter ranges. In this way, a frequency dependent line focus is achieved.

Abstract: A beamformer control system includes a primary control and secondary controls so that delay and apodization beamformation profiles can be generated on a dynamic and distributed basis with sparsely sampled base delay and apodization data sets first expanded to the final values by the primary control and then further expanded in the secondary controls associated with multi-processing channels of the beamformer systems. The beamformer control system coordinates the transmit and receive beamformer systems preferably using data sets common to all beamformer systems, and by advantageously specifying to all beamformer systems, processing mode trade-offs among the signal nominal center frequency, the range spatial resolution, and the number of beams. The beamformer control system supports multiple simultaneous beam operation, as well as beam-to-beam adjustable frequency and synthetic aperture operations.

Abstract: A dual mode ultrasonic imager system operative in both a two dimensional 2-D) mode and doppler mode, includes a plurality of transducers for receiving analog ultrasonic signals and converting them to analog electrical signals, and an analog to digital (A/D) converter system for converting the analog electrical signals to digital signals for further processing. The A/D converter system includes a digital to analog (D/A) converter for converting the digital signals into analog feedback signals, and an analog summer for receiving the analog electrical signals and combining them with the analog feedback signals. An integrator is selectively coupled to receive an output signal from the analog summer and to generate an integrated analog signal. An A/D converter selectively receives, and converts to an equivalent digital signal, one of the integrated analog signal and an output signal of the analog summer.

Abstract: An optical communication system for ultrasound imaging systems employs a light source and photodetector array in the imaging console. The light source and photodetector array are coupled to each other through an optical fiber passing through the probe. Information from the probe is communicated to the console by an optical modulator, situated in the optical path from source to detector. The ultrasound signals are converted into electrical signals by probe electronics, and these electrical signals serve to alter either the phase or amplitude of optical signals passing through the modulator. Since the light source and photodetectors reside in the imaging console, very little power is dissipated in the probe.

Abstract: A method and apparatus for imaging underwater targets utilizing sidelooking onar. A sonar pulse consisting of a concatenated series of subpulses is transmitted. The echo return is match filtered against each of the subpulses to produce a series of range-doppler maps, each providing information in a different direction. The range-doppler maps are normalized, thresholded, and intersected, thereby yielding data points which describe the target outline. Information as to the target length, width and orientation can be computed from the target outline data.

Abstract: An ultrasonic imaging system provides dynamic focusing by using dynamic group delay in addition to dynamic phase focus. FIFO memory storage capacity in the beamforming circuit is increased to provide improved resolution of the data samples stored therein. These samples are selected by an address counter in response to both the advance of time and the accumulation of a phase advance clock count. After a Read Start signal, indicating the start of a beam, is supplied to the FIFO memory, the FIFO memory address is advanced, on each read instruction, by the number of address locations corresponding to the period of a pipeline channel. In addition, the address is incremented whenever the accumulated count of a phase advance clock exceeds an amount corresponding to the smallest increment of the data stored in the FIFO memory.

Abstract: Apparatus for imaging an object underwater. A detector array of operationally independent transducers is deployed in a medium such as water. Each transducer generates an electrical signal across independent first and second electrodes corresponding to impinging acoustic energy. Each of the positions in the detector array is identified in sequence along with the identification of a corresponding pixel position or display position in a display structure. A first multiplexer connects to all the first electrodes and a second multiplexer connects to all the second electrodes to enable the identification circuit to select corresponding electrodes for each detector position. A single amplifier circuit couples the signals from the multiplexer to a circuit for controlling the illumination of a selected display position.

Abstract: An array of acoustic sensors is positioned near the object to be imaged so that an array of detection beams impinge upon the surface of the object. The ambient noise in the ocean which is generated by both natural and manmade phenomena is reflected off of the target object and collected by the acoustic sensors. Each beam corresponds to a single pixel of an image of the object. The amplitude and frequency differences between the signals derived from each beam permit contrast to be developed between the pixels so that an image is formed. A first embodiment utilizes a parabolic or spherical reflector to focus the noise reflected from the object onto one or more sensors. A two dimensional array of sensors is required to produce an image. A second embodiment uses a phased array of acoustic sensors to form an image, with the phased array of sensors being used to generate a large number of scanned beams, each beam corresponding to one pixel of the image.

Abstract: An ultrasonic transducer is provided which has multiple apertures in at least the elevation direction, and preferably in both the elevation and azimuth direction. Each aperture has a selected focal length, with the focal length increasing with the size of the aperture. By transmitting multiple scan lines at a given angle using the different apertures and line splicing received echo signals, resolution is enhanced by utilizing only the portion of each received scan line for which the corresponding elevation aperture is focused. While different controlled elevation apertures may be utilized for transmit and receive, the same aperture is preferably used for both. Additional techniques are discussed for both further enhancing resolution and for mitigating the decrease in frame rate which results from shooting multiple scan lines at a given angle.

Abstract: An apparatus and method for clutter elimination from signals which digitizes a signal to generate n samples of the signals. M basis functions (such as various levels of filters) are fit to the n samples. An i+1 basis function of the m basis functions is iteratively subtracted from each of the n samples, and the difference is stored in an i difference signal until the i+1 difference signal is less than a threshold. In various embodiments, the threshold may be an absolute noise floor (R.sub.O.sup.min) preset by a manufacturer or a user. In other embodiments, the threshold may be based upon an absolute or relative predictor error of the signal once the basis function (filter) has been removed. The i difference signal may be used for performing a frequency estimate of the signal.

Abstract: A method to quantify the distortions caused by near filed variations in the propagation medium of pulse echo imaging systems. By estimating the phase lags induced by the aberrator at each point on the aperture, appropriate electronic delays might be applied to the signals associated with each array element in order to restore the system to focus. The method is capable of estimating the set of aberrating delays in an imaging phased array by using appropriate data from a single two or three dimensional pulse echo scan.

Abstract: For suppressing reflections of an acoustic reception signal at a transmitting/receiving ultrasound transducer, the ultrasound transducer is connected to a compensation circuit which supplies the ultrasound transducer with a compensation transmission signal during reception, which has a waveform similar to the acoustic reception signal, but with a polarity opposite that of the acoustic reception signal. A summing stage is connected in a reception channel of the ultrasound transducer, the summing unit having a first input supplied with a compensated reception signal, formed by a combination of the acoustic reception signal and the compensation transmission signal. A second input of the summing unit is connected to the compensation circuit, which supplies a signal at the second input which removes the contribution made by the compensation transmission signal from the compensated reception signal, so that the output of the summing unit generates a reception signal devoided of the compensation transmission signal.

Abstract: Signal processing apparatus and methods for elimination of undesirable clutter signals from desirable signals. This is performed without the use of filters by subtracting orthonormal basis functions from signal samples until the appropriate degree of clutter removal is achieved. Estimates of frequency information such as Doppler shifts due to fluid flow may thus be achieved with superior discrimination of true flow signals from sources of clutter or artifact, greater sensitivity to low flow rates, minimal computational effort and with fewer samples than the prior art.

Abstract: Coherent light is projected through a scattering medium. The light emerging from the medium is a superposition of a multitude of scattered wavelets, each of which represents a specific scattering path. These wavelets are projected onto a diffuse reflecting surface (the viewing plane of a two-dimensional photodetector array) where they interfere with each other, giving rise to a speckle pattern. By introducing a focused ultrasound pulse into the medium, the position of the scatterers are changed at a known location (probe region) in the medium, and this causes a change in the speckle pattern. By comparing speckle images before and after the scatterers are moved, the light absorption properties of the probe region can be measured even though multiple scattering interferes with direct imaging of the region.

Abstract: A method and apparatus for the generation of a three-dimensional image representing structures detected within a volume. Two dimensional differential phase measurements are made on backscatter signals. Azimuth, elevation and range are calculated over a statistically large number of spatially diverse backscatter returns and used to construct a histogram of backscatter data. The histogram of backscatter data can be processed with standard image processing techniques to produce terrain maps or volumetric models of the volume of water. A system constructed according to the methods of this invention is capable of producing a three-dimensional map of the volume insonified without mechanical array scanning or electronic beam scanning. A combination of two or more volumetric scanning systems can be used to increase the resolution achievable in modelling the volumetric area.

Abstract: A method and apparatus are provided for utilizing a digital front end in a phased array system such as an ultrasonic scanning system to simultaneously perform both digital beam formation and scan conversion. Echo signals from each of the N channels of the array aperture are sampled at selected points along returning echo signals. The samples are preferably used to determine a value for each channel for each pixel utilized in the display by, for example, determining a transmit time for such point. The values for each pixel for the N channels are then summed to obtain the value for the pixel. Alternatively, the samples may be taken at uniform intervals along each channel line and the sample values interpolated to obtain values at Y-boundary crossings or sampling may be taken at times determined so that each sample is at a Y-boundary crossing. The Y-boundary crossing sample values are stored and are then summed to obtain coherently enhanced sample values at the crossings.

Abstract: For reducing speckle in echo signals derived from reflections of pulsed coherent waves, the echo signals are subjected to amplitude and phase/frequency demodulation and the resultant amplitude and phase/frequency data are multiplied to generate an image signal. Selective control of the multiplication process may be provided in accordance with signal amplitude and/or signal-to-noise ratio.

Abstract: A foreground image is overlaid over a background image on a visual display. Specifically, an ultrasound signal is transmitted toward a target to be displayed in two dimensions. Echoes of the ultrasound signal are received from the target. Two-dimesional target data acquired from the received echoes are stored. The two-dimensional target data are presented on the visual display as a background image. Part of the target data are overlaid over the background image as a foreground image on the visual display. The size of the foreground image vis-a-vis the background image is changed by the user to permit better observation of an area of interest. Preferably, the size of the foreground image is changed without changing the area occupied by the foreground image on the visual display, which permits the invention to simulate the action of a magnifying glass. The user moves a cursor on the visual display to the center of an area of interest.

Abstract: A PASS ultrasonic system performs a scan in which phase errors due to aberrations in the sound media are corrected prior to the acquisition of each beam. Phase errors are measured by cross correlating each of a set of reference beams with the desired beam to produce beam forming errors as a function of beam angle. This function is Fourier transformed to produce phase corrections that are employed by the ultrasonic system to offset the phase errors.

Abstract: The invention pertains generally to ultrasonic imaging systems and is more particularly directed to use of such systems for nondestructive testing to measure the thickness of parts, or to examine parts suspected of having internal flaws but where access is often limited to the external surfaces. The invention makes thickness and flaw determinations of substantial accuracy without resulting to use of an expensive ultra high frequency clock to measure time.

Abstract: A method of locating objects in sonar images so that matching algorithms can be used to determine if the same objects appear in two images. Information from the matching algorithms can then be used to upgrade the position of the vehicle and objects recorded in the vehicle's navigation system. Images are improved by normalizing brightness and contrast and then convolving the image with at least one filter. The image is normalized by dividing the image into vertical strips, creating a histogram to represent the grayness values for columns of pixels in each strip and applying an algorithm to each strip to change its grayness value.

Abstract: The train of echoes received in an ultrasound imaging system having an array of ultrasound transducers is shaped and/or focused by first and second programmable beam focusing modules (16-24) in a dynamic receive focus mode. The elemental ultrasound echo signals from a plurality of channels connected to the elements of the transducer array are selectively attenuated and/or phased shifted according to the programs prescribed for the focus zones and combined by each module. The combined echo signals are further processed in conventional fashion (34-38). The modules operates alternately. One module is being programmed, while the other module is combining the elemental echo signals for processing. Each beam focusing module comprises a delay line (56-60) having a plurality of input taps and a cross point switch (52) selectively connecting the channels to the input taps. The module is programmed by selectively closing the individual cross points of the cross point switch. Beam shaping i.e.

Abstract: A phased array sector scanning ultrasonic imaging system produces digitized baseband samples of the received ultrasonic echo signals amplified by a time gain control (TGC) to compensate for dispersion losses in the media in which the ultrasonic signals propagate. A time frequency control filter employs the same TGC control signal to calculate a phase shift correction as well as the coefficients which determine the characteristics of a bandpass filter such that the frequency dependent dispersion losses in the ultrasonic echo signals are compensated.

Abstract: The train of echoes received in an ultrasound imaging system having an array of ultrasound transducers is shaped and/or focused by first and second programmable beam focusing modules (16-24) in a dynamic receive focus mode. The elemental ultrasound echo signals from a plurality of channels connected to the elements of the transducer array are selectively attenuated and/or phased shifted according to the programs prescribed for the focus zones and combined by each module. The combined echo signals are further processed in conventional fashion (34-38). The modules operates alternately. One module is being programmed, while the other module is combining the elemental echo signals for processing. Each beam focusing module comprises a delay line (56-60) having a plurality of input taps and a cross point switch (52) selectively connecting the channels to the input taps. The module is programmed by selectively closing the individual cross points of the cross point switch. Beam shaping i.e.

Abstract: The present invention is generally directed to an apparatus and method of echo identification wherein the sources of echoes generated from interface boundaries in a medium may be more effectively identified in the processing of obtained waveform data to generate higher resolution in the obtained data. The method of the present invention is particularly useful for performing ultrasound reflectometry and medical sonography by obtaining data representative of a medium being studied and suppressing signals from overlapping echo waveforms generated from obstacles adjacent an object under test. More particularly, the method of the invention enables the sources of such echo waveforms to be more effectively identified to yield an indication of the contribution of overlapping echoes to generate higher resolution data signals. The processing includes generating a power spectral estimate of the data which is utilized to obtain a phase estimate thereof.

Abstract: An acoustic device and related method for measuring the shape of an object. The device includes a plurality of transmitters for transmitting acoustic waves at an object to be measured and a plurality receivers for receiving the acoustic waves reflected by the object. A phase detector measures phase data of the reflected acoustic waves, the phase data being processed to calculate a value representing a shape of the object as a function of the phase data. This value is then compared with known reference value to accurately identify the shape of the object.

Abstract: An acoustic receiving array synthesized using a single stationary receiving lement and a rotating target. Echoes from a highly repeatable transmit pulse are digitized and recorded as the target is rotated. Controlled geometry and essentially stationary channel characteristics eliminate the need for adaptive beamforming techniques. Subsequent to acquisition of the desired data set conventional time delay beam-forming and steering techniques for multi-dimensional arrays are used to focus the array at desired locations. Energy level in a time gate is computed and recorded for each image location. Finally a raster image is generated using the thresholded energy levels.

Abstract: A sonar system including an elongated transducer having a fully populated or non-fully populated array of transducer elements. During course of travel of the carrier on which the transducer is mounted, successive acoustic transmissions take place whereupon the transducer elements provide output signals in response to the reflected energy. At least one synthetic aperture beam is formed by combining the element output signals from at least two successive transmissions wherein there is a predetermined gap between the array at a location at which a first transmission takes a location at which a subsequent transmission takes place.

Abstract: An ultrasonic microscope comprises an ultrasonic pulse transmitting/receiving circuit for emitting an ultrasonic to a sample and receiving an echo from it, a scanner for scanning the sample in a direction normal to the direction of emitting the ultrasonic pulse, an extraction circuit for sampling the output signal of the ultrasonic pulse transmitting/receiving circuit at a given duration and at given intervals to extract echo data signals of plural depths in the sample, a first memory for storing B mode image data attained by a single scanning, a second memory for storing, as 3D image data, the B mode image data sequentially read out from the first memory, an image processor for reading out the image data from the second memory for image processing, and a display device for displaying the processed image data as a 2D or 3D image.

Abstract: An ultrasound apparatus has a transducer array which includes a number of individual transducer, each transducer having a channel exclusively associated therewith. In an input stage for the ultrasound apparatus, an analog stage is provided in each channel to which the echo signals for a transducer associated with that channel are supplied. This analog stage concludes with an analog-to-digital converter in each channel. The output of the analog-to-digital converter is connected to a further processing circuit in each channel for the acquisition of Doppler signals of moving target echoes. A combined ultrasound imaging device and Doppler device is thus achieved, which allows the acquisition of Doppler signals with the digital input technology of the ultrasound imaging processing circuit. This permits expansion of digital operating RF input components of imaging devices to include Doppler signal processing.

Abstract: A volume is scanned with a raster scan about a center of rotation using a transmitter/receiver at a selected range while gating a range window on the receiver with a selected range differential. The received signals are then demodulated to obtain signals representative of a property within the volume being scanned such as the density of a tumor. The range is varied until the entire volume has been scanned at all ranges to be displayed. An imaging display is synchronously scanned together with the raster scan to display variations of the property on the display. A second transmitter/receiver with associated equipment may be offset from the first and variations displayed from each of the transmitter/receivers on its separate display. The displays may then be combined stereoscopically to provide a three-dimensional image representative of variations of the property.

Abstract: Imaging apparatus including an array of transmitters for simultaneously transmitting more than two coded signal beams in different directions to cover different regions of a field of view, said beams being modified by objects within said field of view, signal means for providing individual coded signals to respective transmitters, at least one receiver for simultaneously receiving plural coded modified signals derived from the coded signal beams, and a processor for separating the plural coded modified signals of different codes and processing them into an image signal.

Abstract: An ultrasonic imaging arrangement. The arrangement includes a probe having an array of oscillators for emitting ultrasonic waves toward an object to be tomographically imaged, a first converter, a line memory group including a plurality of line memories, a write zoom operation unit, a frame memory, read zoom operation unit and a second converter. Echo signals reflected from the object are converted into digital signals as ultrasonic data. The ultrasonic data are stored in the line memory group, and are stored in the frame memory after processing operations in the write zoom operation unit. The read zoom operation unit then reads the data from the frame memory and, if necessary, processes that data. The second converter converts the processed data into video signals and a tomography image of the object is displayed according to the video signals.

Abstract: Ultrasound imaging apparatus having an array of electro-acoustic transducer rings, means for exciting said transducer rings in sequence so as to cause them to transmit successive pulses of pressure waves along a path at intervals at least equal to the time of transit of the pressure waves to a maximum range and back to the array, dynamically controlled delays respectively coupled to each transducer ring that bring the electrical signals the transducers supply in response to pressure of waves of each pulse that are reflected along a given range into reasonable phase coherence, processing means coupled to the delays so as to provide a composite signal, and a summing memory coupled to receive the composite signal.

Abstract: An ultrasonic imaging apparatus comprises an ultrasonic transducer comprised of a plurality of ultrasonic transducer elements arranged in one direction, a transmission section for driving the ultrasonic transducer to radiate first and second ultrasonic beams from the ultrasonic transducer at a time in their different directions, and a receiver section for processing echo signals which are obtained from the ultrasonic transducer means and for outputting first and second television signals. Television signals are displayed as two lines of raster on a monitor.

Abstract: A method and apparatus for processing ultrasonic echo signals employ intermediate storage and representation of the echo signals in the form of image vectors, such storage and representation proceeding independently of the scanning technique utilized to generate the image vectors, such that switching among various scanning techniques is permitted. The full length of each image vector is written into an image memory in column fashion, the stored vectors being read out as image signals in a format suitable for specific types of representation, such as on a television monitor, the format instructions being contained in a memory or generated by an arithmetic unit. Upon read out from the image memory, the geometric form of the ultrasonic scan is reconstructed in a position and form corresponding to the actual scan, and the ultrasonic echo signals are similarly represented at their true positions.

Abstract: Apparatus (and method) for parts sorting and the like wherein parts and the like are transported into an interaction region and irradiated with wave energy which interacts with the parts and the like to provide wave energy that emits from the interaction region. The positions of the parts and the like as they move through the interaction region are detected at spaced locations along the path of travel therethrough. The wave energy that emits from the interaction region is sensed to derive a characteristic of the parts and the like at each of the spaced locations to provide signals from which the characteristic can be determined. The signals are analyzed for each spaced location to derive data representative of the characteristic which serves as the basis for sorting.

Abstract: A system to measure geometric and electromagnetic characteristics of objects. Wave energy of a single frequency (or very narrow band of frequencies) is directed upon an object which reflects (or otherwise interacts with) the wave energy. The reflected wave energy is sensed by many spatially spaced sensors to provide electric signals whose amplitude and phase components are combined to give a quantity from which geometric and/or electromagnetic characteristics of the object can be ascertained.

Abstract: A multielement acoustic transducer comprising a metal plating which is formed by plating the convex surface of a low-melting metal having a plurality of convex semispherical holes and then fusing and removing the low-melting metal, the metal plating being used as a base electrode, a piezoelectric material which is formed on the base electrode, and a top electrode which is formed on the piezoelectric material, the piezoelectric material functioning as concave transducer elements.

Abstract: A bidimensional imaging system by echoes including a transmitting array and a receiving array. The transmitting array includes a row of transmitters (E.sub.1, E.sub.2, . . . , E.sub.i, E.sub.N) parallel to a direction Oz and the receiving array includes a row of receivers in a direction Ox. All the transmitters simultaneously transmit signals with different codes. The signals received are demodulated and the real and imaginary components of these signals are applied to two multiplexing circuits (61.1, 61.2). After modulation the multiplexed signals are applied to a Fourier transformation circuit (63), which sequentially supplies reception channels V.sub.k (.theta..sub.k) for the direction referenced by angle .theta..sub.k and which are stored in memories (66.1, 66.2). Other memories (70.1, 70.2) contain signals S.sub.i (.phi..sub.i) transmitted in an angular direction referenced by .phi..sub.i. The two pairs of memories (66.1, 66.2 and 70.1, 70.

Abstract: A method and apparatus are described for holographically generating visual representations of acoustical characteristics of sound sources. A planar array has a lattice of microphone receiving points are disposed such that evanescent wave energy from the sources is detected along with propagating wave energy. The microphone outputs are sampled, resolved into phase and amplitude components, digitized and subjected to fast Fourier transform operations to provide computer graphic display means with holographic reconstruction parameters corresponding to the sources under analysis.

Abstract: A system for detection by an echo containing transmission and reception sources for detection by acoustic waves in particular. A circular base with N columns T.sub.1, T.sub.2, -T.sub.i,-T.sub.N of electroacoustic transducers. To each column such as T.sub.i corresponds a transmission at the frequency f.sub.i. A switch makes it possible to change from transmission to reception. The signals received are applied to a channel forming device. For each channel such as V.sub.k the signals are filtered at frequencies f.sub.1, f.sub.2, -f.sub.N, which are applied to time offset circuits taking into account the base geometry and the channel direction. The signals obtained such as d.sub.i.k are applied to a display device which supplies the range, direction and speed of the targets detected. This is particularly applicable to underwater surveillance by sonar or radar.

Abstract: An acoustic imaging system enabling images in two dimensions to be obtained. The system contains an array formed by M transmitter transducers E.sub.1, E.sub.2, . . . E.sub.M, supplying separable coded signals of the same frequency and a reception array with at least one line of hydrophones, H.sub.1, H.sub.2, . . . H.sub.N. The signals such as h.sub.i received by each of the hydrophones are applied to processing circuits such as D.sub.ik supplying signals x.sub.ik and y.sub.ik, which are multiplexed in circuits MX and MY in a given order, placed on a carrier and applied to an analog Fourier transform device with filters dispersive to acoustic waves. After detection, the system supplies a line of images.

Abstract: In an echo sounder including a cathode-ray tube display device for providing a visual display in the form of a succession of image frames each composed of a series of image lines extending in a first direction on the display and spaced apart in a second direction on the display, with each line being composed of a plurality of image points, and a memory having a number of addressable memory locations equal to at least the number of image points in each frame, with a representation of each image point being stored at a respective memory location, the memory is an addressable read-write random access memory, and the device includes circuitry connected for causing each memory location address to consist of a first part identifying the location of one image line in the second direction on the display and a second part identifying the location of one image point along any line in the first direction on the display, an address counter producing an output representing the address part corresponding to one direction,

Abstract: Pixel data stored in a display memory of an ultrasonic scanning system is updated in response to new pixel data generated from a reflected ultrasonic wave and stored pixel data. A lookup table of pixel values is provided in a second memory, and the second memory is addressed using the new pixel data and the stored pixel data. The value stored in the second memory at the address is then used to update the display memory.

Abstract: An imaging sonar system is disclosed comprising a transmitter, a receiver, and a rotatable transducer coupled with the transmitter and receiver for generating sound waves and for detecting echoes therefrom. Drive means are provided for rotating the rotatable transducer. Transducer position sensing means are provided for sensing the rotary position of the transducer. Analog to digital converter means are coupled with the receiver for converting receiver emitted signals into digital form. Serial access memory means are provided entering into storage receiver emitted signal data in digital form at a preselected rate and for withdrawing from storage receiver emitted signal data at a rate different than the predetermined rate. Write and read control means are also provided for respectively entering digital data into and recalling digital data from the memory.

Abstract: A scan converter is disclosed for use in a sector scan type ultrasound imaging system in which ultrasound echo signals return from targets along a plurality of radial scan lines distributed in a sector field with a substantially equal tangential angular increment with respect to a reference line. The scan converter comprises a sampling circuit which samples the echo signals at a speed inversely proportional to the cosine of the angle of deflection of the radial scan lines with respect to the reference line so that the sampled points align themselves in lateral lines perpendicular to the reference line. The sampled echo signals are converted into digital echo data and stored in a random access memory in the direction of its columns. The stored data are retrieved serially in the direction of the rows and fed into an interpolator for making interpolations between the successively retrieved echo data.

Abstract: A conical acoustic lens in conjunction with a ring of transducer elements located on a circle disposed above the lens is utilized to form a plurality of radial beams for imaging a target area beneath the apparatus. The transducers may occupy the fully 360.degree. of the circle or a sector less than 360.degree. in which the case the apparatus may be rotated to give full 360.degree. coverage.

Abstract: A contour map underwater ultrasonic image system simultaneously uses a la time-bandwidth product signal waveforms for extremely fine range resolution, and an image memory organized as a three-dimensional data base of object reflectivity. The transmitted waveform is a pseudo-random coded signal. A plurality of correlator receivers produce a time-compressed pulse for each angular resolution cell. An image memory receives the output of the correlator receivers and builds up a three-dimensional data base of echoes in the form of a set of contour lines for each range cell. Standard computer-graphic techniques are used to accept the three-dimensional data base and generate displays to assist an operator in identifying the object.