Apparatus for improved underwater acoustic telemetry utilizing phase coherent communications
First Claim
1. Apparatus for high data rate digital underwater communication over an underwater acoustic channel comprising:
- means including a transmitter at a first location for horizontally transmitting a carrier modulated by a phase coherent stream of data corresponding to symbols;
means including a receiver at a second location for detecting and demodulating said stream to remove channel induced degradations in said stream, said receiver including means for decision feedback equalization, thereby to recover undegradated data in the form of symbols; and
,means for displaying said received symbols, whereby phase coherent communications is established despite an underwater acoustic channel which changes rapidly and ordinarily restricts the data rate.
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Accused Products
Abstract
An underwater acoustic communications system utilizes phase coherent modulation and demodulation in which high data rates are achieved through the use of rapid Doppler removal, a specialized sample timing control technique and decision feedback equalization including feedforward and feedback equalizers. The combined use of these techniques drammatically increases data rates by one and sometimes two orders of magnitude over traditional FSK systems by sucessfully combating fading and multipath problems associated with a rapidly changing underwater acoustic channel that produce intersymbol interference and make timing optimization for the sampling of incomming data impossible.
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Citations
20 Claims
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1. Apparatus for high data rate digital underwater communication over an underwater acoustic channel comprising:
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means including a transmitter at a first location for horizontally transmitting a carrier modulated by a phase coherent stream of data corresponding to symbols; means including a receiver at a second location for detecting and demodulating said stream to remove channel induced degradations in said stream, said receiver including means for decision feedback equalization, thereby to recover undegradated data in the form of symbols; and
,means for displaying said received symbols, whereby phase coherent communications is established despite an underwater acoustic channel which changes rapidly and ordinarily restricts the data rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A high data rate underwater acoustic communications system for transmitting and receiving symbols comprising
means for transmitting and receiving information between two laterally spaced locations, said information being transmitted digitally in phase coherent form, with said data rate exceeding 600 bits per second.
Specification