Abstract: A network node apparatus is disclosed for the capture, storage and replay of video data at separate respective nodes of a communications network arranged to operably couple the node apparatus. The node apparatus may include a video capture node operable to capture video data and to transmit captured data via the communications network to a video storage node. The video storage node is arranged to store captured video data, and to transmit stored data via the communications network to a video replay node which renders an image therefrom. The video storage node transmits video data to the video replay node only if the content of a transmit buffer therein matches or exceeds a predetermined lower content value and the content of a receive buffer in the replay node does not exceed a predetermined upper content value.

Abstract: A network node apparatus is disclosed for the capture, storage and replay of video data at separate respective nodes of a communications network arranged to operably couple the node apparatus. The node apparatus may include a video capture node operable to capture video data and to transmit captured data via the communications network to a video storage node. The video storage node is arranged to store captured video data, and to transmit stored data via the communications network to a video replay node which renders an image therefrom. The video storage node transmits video data to the video replay node only if the content of a transmit buffer therein matches or exceeds a predetermined lower content value and the content of a receive buffer in the replay node does not exceed a predetermined upper content value.

Abstract: The present invention provides an optical filter including a substrate having a plurality of layers of materials stacked upon it each of which layers is formed from one or both of: a first material having a first index of refraction; and, a second material having a second index of refraction being less than the first index of refraction; wherein the plurality of layers of materials include a first layer and a second layer each formed from an inhomogeneous mixture of said first material and said second material; and a third layer formed from the first material being stacked in between the first layer and the second layer; wherein the optical thickness of each of said first and said second layers is greater than the optical thickness of said third layer.

Abstract: An apparatus for towing behind an underwater vehicle has a body and a yoke pivotally connected to the body at a pivot point and having a tether remote from the pivot point by which the apparatus us towed. The yoke has wings which generate a resultant force on the body when the apparatus is towed. By varying the orientation of the yoke relative to the body, the magnitude of the resultant force may be varied. The resultant force tends to reduce the displacement of the tether relative to the pivot point in at least one plane, thereby generating a force to counter the buoyancy of the apparatus, and so stabilize the apparatus when it is being towed.

Abstract: There is disclosed an actuator (5) having an actuator chamber (6) and actuator piston (9) therein defining an extend chamber (10) and a retract chamber (7) separated from the extend chamber by the actuator piston. A first fluid pump (A) is in fluid communication with the extend chamber and the retract chamber and is arranged to transfer therebetween volumes of fluid substantially equal in magnitude to changes in the volume of the retract chamber resulting from movement of the actuator piston within the actuator chamber. A second pump B connected to the extend chamber and to an accumulator (17) allows the differential volume between the extend and retract chambers to be displaced into the accumulator at a pressure. Stored accumulator fluid pressure enables pump B to be back-driven so that it behaves as a motor whenever the pressure in conduit 15 is less than in conduit 16. A pre-charge (20) unit pressurises the system until full mass counterbalance of the suspended load is achieved.