Standard Telephones and Cables Public Limited Company

Britoil Public Ltd. Co.

Standard Telephone and Cables Ltd. Co.

Kenneth S Darton

Johnathan P Larsen

Jonathan P Larsen

An array of acousto-electric transducers 1,2, e.g. a hydrophone streamer, is calibrated by disconnecting the common ground wire 17, to which all the transducer shields 14 are connected, from ground and connecting it instead to a local oscillator 18. Test signals from the oscillator are capacitively coupled into each transducer via the inherent capacitances of the insulated lead throughs 15, 16 in the transducer shields 14.

Remote calibration of acoustic transducer array

An arrangement for digital multiplexing onto a common highway a plurality of analogue input signals which are physically spaced apart over a distance. m time division multiplexing units 5a each have for each of n separate analogue signals n single channel pulse coding means 6 the outputs of which are time division multiplexed at a common outlet 12. Each multiplexing unit 5a also has a timing circuit 7 which can be either free running or locked to the similar timing circuit of a succeeding unit (5b). Each unit has (m-1) bypass connections 15, 16, 17 so that the multiplexed outlets of succeeding units are fed in parallel to a group multiplexer. The timing circuits, being cascaded, ensure that propagation delays for the digital signals from each of the n analogue inputs are obviated.

Distributed digital signal multiplexing

A magnetic angular position sensor having a ferrofluid filled spherical chamber in a cylindrical housing, within which floats a body comprising a buoyant core carrying a magnet which aligns itself and the body with the earth's magnetic field, and carrying an odd number of small permanent magnets. Hall effect devices are located in recesses in the ends of the housing. The housing also carries a calibration solenoid.

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Bishops Stortford, United Kingdom

Kenneth S Darton