Abstract: An expendable autonomous underwater vehicle is deployed from a trash disposal unit of a submarine into a body of water. The vehicle and one or more launch-aiding components are inserted into the trash disposal in an arrangement that results in safe and reliable deployment from the trash disposal unit. The launch-aiding components keep the vehicle in a predetermined orientation within the trash disposal unit prior to deployment and protect the trash disposal unit from damage. The launch-aiding components also aid the vehicle in ejecting from the trash disposal unit and descending into the body of water to a depth at which the vehicle can begin its autonomous operation. In general, the vehicle must be a safe distance away from the submarine before it begins operation. The launch-aiding components fall away from the vehicle in the body of water as the vehicle descends thereinto.

Abstract: A short baseline navigation system employs the real-time estimation of the positions of multiple cooperative targets. Each target replies with a unique stepped frequency sequence signal that covers the usable frequency band. A processor operates on reply signals received by elements on the tracking platform and develops a coarse time-difference-of-arrival estimate using an algorithm derived herein. The processor also estimates the Doppler shift of received signals, and determines a time-window (or gating) that eliminates the portions of the received signals corrupted by multipath interference. The relative phase differences between the received signals are then used in conjunction with the coarse time-difference-of-arrival estimates for a precise direction-of-arrival estimation.

Abstract: A system of sonar platforms designed for use in moderate depth water is disclosed, with each platform having a plurality of transducer modules mounted thereon. Each transducer module has a plurality of sonar transducers mounted in columns. The transducers are electronically grouped in two groups for sensing of reflected signals, to provide a means of bearing calculation by the phase monopulse method. The transducer modules are identical and interchangeable, so that any module can be mounted in any position on any platform. Each platform is hexagonal, with up to six transducer modules mountable on each platform to provide the desired pattern of sonar coverage for the platform. The platforms can be arranged in any desired pattern to provide the desired sonar coverage of a particular body of water.

Abstract: An undersea release apparatus for positively releasing a connecting link from an underwater device, the apparatus comprising a latching mechanism on the device for latching the connecting link to the device in a latched condition, and for unlatching the connecting link to be free of the device in an unlatched condition. A driving mechanism positively moves the latching mechanism to its unlatched condition. The driving mechanism drives a rotatable cam which retains a pelican hook at a fixed latched position, and positively drives the pelican hook from the latched position to an unlatched position. The apparatus is also provided with an arming function, whereby the rotatable cam is rotated in a direction opposite to that which is effective to unlatch the connecting link, whereby the pelican hook is pivoted back to its first or latched position in which the pelican hook relatches with the connecting link.

Abstract: A system and method for identifying a route for excavation of an underwater trench on the seafloor includes a surface vessel, a plurality of penetrometers and an onboard computer. As the surface vessel plies along a proposed route for the underwater trench, penetrometers are launched from the vessel at selected launch points. Upon impact of a penetrometer with the seafloor, acoustic signals transmitted from the penetrometer during the impact event are analyzed by the onboard computer. From this computer analysis the seafloor at the impact point is classified as being in either a first state indicative of proceeding along the proposed route or a second state necessitating a deviation from the proposed route. Depending on the state of the seafloor and the number of deviations needed, the proposed route is returned to and followed, or a new proposed route is established. Data from the impact events are subsequently compiled to establish an actual route for excavation of the underwater trench.

Abstract: A selectively configurable penetrometer device for impact testing the physical characteristics of the sea floor includes a hollow cylindrical housing which is formed with a recess. A hemispherical nose is engageable with one end of the housing and a removable fin assembly is selectively engageable with the opposite end of the housing. A transponder is engageable in a fluid tight seal with the end of the housing opposite the hemispherical nose to hold the electronic components in the recess of the housing. In the operation of the penetrometer, the transmitter emits a signal of precisely controlled constant frequency, and a remote receiver detects variations in signal receptions during impact of the penetrometer with the sea floor to determine the physical characteristics of the surface of the sea floor. The device can also include weighted spacers which can be selectively inserted into the device between the housing and the hemispherical nose.

Abstract: A signal processing system for determining sea floor composition based on the frequency waveform and Doppler shift transmitted from an acoustic penetrometer includes a hydrophone for receiving the penetrometer waveform. The hydrophone output is digitized and passed to a general purpose computer where it is analyzed by a signal processing program. The signal processing program performs various signal transformations to increase the quality of the input waveform and isolates a penetration event. Additionally, the input signal is converted to an equivalent velocity waveform. A curve fitting algorithm is then used to determine the points within the velocity waveform that mark the initiation and termination of the penetration event that corresponds to the impact of the penetrometer with the sea floor. Once the initiation and termination of the penetration event are known, the velocity waveform is numerically integrated between those two points.

Abstract: A system for acoustically positioning a noisy platform. An array of transponders, adapted to be deployed in a region of water, is provided. A transducer is mounted on the noisy platform and another transducer is mounted on a relatively quiet vehicle tethered to the platform. A first means is provided for transmitting acoustical energy from the transducer on the noisy platform to said array and from said array to said transducer on said vehicle for measuring the distance from said noisy platform to said quiet vehicle via said transponders in said array. A second means is provided for transmitting acoustical energy from the transducer on said vehicle to said array and back to said vehicle for measuring the distance said vehicle is from the transponders in said array. Calculating means is coupled to said first and second means for determining the location of said noisy platform relative to said array.

Abstract: A ranging system employing a limiting constant false alarm rate (CFAR) receiver having reduced recognition time uncertainty, or recognition jitter. The jitter is made proportional to signal-to-noise ratio by providing the receiver with a two-part signal. A conditioning signal is provided to the receiver prior to the time the receiver is expected to sense and respond to a recognition signal for ranging. The conditioning signal has selected strength and duration sufficient to suppress noise to a desired extent in the receiver at the time the recognition signal is received. The combination of strength and frequency of the conditioning signal is selected so as to limit the probability of a false alarm, or undesired recognition of the conditioning signal in the receiver. Receiver modification is not required.