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US 6,687,188 B2Granted
Underwater telemetry apparatus and method
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorTsih Yang
Life of this patent
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AssigneeThe United States of America as represented by the Secretary of the Navy
InventorTsih Yang
Estimating the term…
An apparatus for phase coherent underwater communications includes a transmitter; a receiver, including a processor for jointly performing coherent diversity combining, carrier recovery, channel equalization and synchronization; and an antenna array that includes a plurality of antenna sub-arrays for alternately transmitting a signal generated by the transmitter and for receiving an incoming signal. Each of the antenna sub-arrays includes a plurality of underwater sensors positioned such that each of the sensors is spaced at about one half the wavelength of the receiver/transmitter operating frequency from any adjacent sensor in the same sub-array. At least one of the sub-arrays has a centerpoint vertically spaced apart from a centerpoint of an adjacent sub-array at a distance about equal to or larger than a vertical correlation length of a received signal. The individual sub-arrays are beamformed, e.g. using a plane-wave delay-and-sum (or phase-steering) method. The outputs of the sub-array beamforming are used as inputs to a diversity-combining algorithm. Although a total of many elements of underwater sensors are used physically, the communications algorithm (the channel equalizer) sees effectively only a small number of channels. This reduces the required processing time by orders of magnitude.
A phase coherent underwater communications channel antenna array, comprising:
An apparatus for phase coherent underwater communications, comprising:
A method for conducting underwater communications, comprising the steps of:
Dependencies are inferred from the claim text.