Abstract: A navigation system extends satellite navigation to divers, underwater vehicles, and surface vessels. The navigation system comprises a location reference unit and a plurality of sub-surface beacon units. The location reference unit includes a receiver to receive navigation signals from earth-orbiting satellites and/or an inertial navigation system. The location reference unit further includes control circuits to communicate with to sub-surface beacon units and to transmit location information to said sub-surface beacon units, and a transceiver to transmit location information to the sub-surface beacon units. The beacon units include control circuits to determine the location of the beacon unit based on location information received from the location reference unit, and a transceiver to receive location information from the location reference unit and to transmit location information to a guided unit to provide navigation assistance to the guided unit.

Abstract: A diver unit computes the direction and distance to a specified target. When the target is obstructed, the diver unit receives navigation assistance data from another diver unit. The navigation assistance data includes direction information that is referenced to a common reference line extending between the two diver units.

Abstract: A navigation system extends satellite navigation to divers, underwater vehicles, and surface vessels. The navigation system comprises a location reference unit and a plurality of sub-surface beacon units. The location reference unit includes a receiver to receive navigation signals from earth-orbiting satellites and/or an inertial navigation system. The location reference unit further includes control circuits to communicate with to sub-surface beacon units and to transmit location information to said sub-surface beacon units, and a transceiver to transmit location information to the sub-surface beacon units. The beacon units include control circuits to determine the location of the beacon unit based on location information received from the location reference unit, and a transceiver to receive location information from the location reference unit and to transmit location information to a guided unit to provide navigation assistance to the guided unit.

Abstract: A navigation system extends satellite navigation to divers, underwater vehicles, and surface vessels. The navigation system comprises a location reference unit and a plurality of sub-surface beacon units. The location reference unit includes a receiver to receive navigation signals from earth-orbiting satellites and/or an inertial navigation system. The location reference unit further includes processing circuits to communicate with to sub-surface beacon units and to transmit location information to said sub-surface beacon units, and a sonar transmitter to transmit location information to the sub-surface beacon units. The beacon units include processing circuits to determine the location of the beacon unit based on location information received from the location reference unit, and a sonar transceiver to receive location information from the location reference unit and to transmit location information to a diver unit to provide navigation assistance to the diver unit.

Abstract: A diver unit computes the direction and distance to a specified target. When the target is obstructed, the diver unit receives navigation assistance data from another diver unit. The navigation assistance data includes direction information that is referenced to a common reference line extending between the two diver units.

Abstract: A navigation system extends satellite navigation to divers. The navigation system comprises a surface unit and a plurality of sub-surface beacon units. The surface unit includes a receiver to receive navigation signals from earth-orbiting satellites, processing circuits to communicate with to sub-surface beacon units and to transmit location information to said sub-surface beacon units, and a sonar transmitter to transmit location information to the sub-surface beacon units. The beacon units include a processing circuits to determine the location of the beacon unit based on location information received from the surface unit, and a sonar transceiver to receive location information from the surface unit while the surface unit is floating on the surface; and to transmit location information to a diver unit to provide navigation assistance to the diver unit.

Abstract: Reflected light from the record in a optical disk player is directed at a string of photo sensitive diodes. Two adjacent diodes of this string of diodes receive light from a selected portion of the track on the disk. The outputs of these two adjacent diodes are summed together to generate the output signal for the optical disk player. The outputs of the two diodes are also subtracted from one another to generate a differential signal for tracking purposes. The magnitude of this differential signal is a measure of the relative magnitudes of the signals on the two adjacent diodes and therefore is one indication of how much of the light from the selected portion of the track reaches each of the diodes. When this differential output becomes larger than a preselected value, decode circuitry responds by changing the combination of adjacent diodes in the string to generate the video output signal and the difference signals.

Abstract: A video recording disk that is optically readable has data represented in a form that permits data track revolutions to be spaced close together without an intervening guardband or with only a narrow guardband. The track revolutions are in two sets that form a parallel spiral or alternating concentric circles so that a track revolution of one set is separated from other track revolutions of the same set by intervening track revolutions of the other set. Binary data is represented on the tracks by deformations or the absence of deformations, and the record is read as destructive interference in a light beam produced at the location of a deformation. Deformations of the first set of tracks have a depth that is appropriate to be read with a wavelength designated lambda 1, and deformations of the second set have a depth to be read by light of a wavelength lambda 2.