Abstract: A network over which a medium is transferred. The network includes S core rings. Each core ring can be modeled as a set of nodes interconnected by links, where S is greater than or equal to 4 and is an integer, each said core ring having at least N nodes, where N is greater than or equal to 4 and is an integer. Each node/link is configurable in terms of directing the medium from a given source toward a given destination, and where each of the core rings is directly connected by means of k spanning links, where k is greater than or equal to 2, so as to comprise a spanning ring to at least a second and a third of the other core rings. The combinations of core rings spanned by each core ring is such that there is a path comprised of links and nodes from each node on any core ring to any other node on any other core ring. A method for transferring a medium.

Abstract: A network over which a medium is transferred. The network includes S core rings. Each core ring can be modeled as a set of nodes interconnected by links, where S is greater than or equal to 4 and is an integer, each said core ring having at least N nodes, where N is greater than or equal to 4 and is an integer. Each node/link is configurable in terms of directing the medium from a given source toward a given destination, and where each of the core rings is directly connected by means of k spanning links, where k is greater than or equal to 2, so as to comprise a spanning ring to at least a second and a third of the other core rings. The combinations of core rings spanned by each core ring is such that there is a path comprised of links and nodes from each node on any core ring to any other node on any other core ring. A method for transferring a medium.

Abstract: A method for eliminating false detections at the water column boundary in side scan sonar images is provided. Each image is filtered by computing the median greylevel value of a pixel and its four adjacent pixels to produce a median image. The median image is filtered with a first linear filter to produce an edge image. The edge image is then filtered with a second linear filter to produce an edge-smoothed image. The edge of the image is detected by searching each row of the edge-smoothed image for the maximum greylevel. A transition region is defined between the detected edge and a preselected right boundary and the average greylevels over the rows and columns in this transition region is computed. The sonar image is then normalized by computing the image mean grayness level of each pixel in the image.

Abstract: An automatic method for finding mines in side scan sonar images using a two-stage detection/discrimination process is provided. This method improves the discrimination process by specialized processing of regions of interest found in the detection process to increase the probability of correctly identifying highlight and shadow regions associated with mine images. Features specifically selected for their ability to discriminate mines are then extracted from these areas for use in the Bayesian discriminator.

Abstract: A time delay-phase shift combination beamformer for applications where the required time delays for time delaying the received signal to achieve coherency exceed the reciprocal of the incoming signal's bandwidth, and having a time delay stage for coarse beamforming at a particular range and first beam direction and a phase shift stage for fine beam steering in a second direction at the particular range.

Abstract: Individual elements of a sonar receiver transducer provide output signals in response to the receipt of acoustic energy and signals are processed to form one or more receiver beams for display. Each element output is provided to a preamplifier to which is applied a time varied gain function. The output signal of at least one of the preamplifiers is additionally provided to an adaptive time varied gain circuit which generates an error signal for correction of the time varied gain function applied to the preamplifiers.

Abstract: A square law detection circuit for energy signals such as sonar signals wherein the signal processing eliminates the side lobe detection of false targets by eliminating the side lobes themselves without significant energy degradation of the main lobe of the beam pattern associated with the sonar equipment.

Abstract: Sonar apapratus which forms concentric hollow conical receiver beams having a common cone axis which is at a predetermined angle relative to the direction of travel of the apparatus as opposed to being coincident with it. A target indication received by a conical beam defines a circle upon which the target might lie. Multiple transmissions and detection of the target in other beams result in intersecting the circles to thereby limit the location of the target to one of two possible points, and one of which may be disregarded depending upon the operational mission.

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.