Spread Spectrum telemetry
First Claim
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1. A spread spectrum telemetry apparatus, comprising:
- a transceiver for transmitting and receiving signals;
a plurality of addressable transponders in a seismic cable;
means for forming a code of digital bits of a data word for transmission to the addressable transponders;
said plurality of addressable transponders comprising means responsive to the code transmitted from said transceiver.
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Abstract
Transponders in or with a shallow water seismic cable emit acoustic signals for acoustic ranging on command from a transceiver aboard a seismic exploration vessel. The acoustic ranging data together with navigational data cna be used to identify cable location. The transponders are activated by individual identifying digital codes. Each such digital code is a data word of suitable length composed of a distinctive frequency sent in bursts for a specific time for successive pairs of bits, or di-bits, in the data word. The time spacing between sending the frequency bursts is also used to carry other di-bits of the data word.
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Citations
16 Claims
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1. A spread spectrum telemetry apparatus, comprising:
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a transceiver for transmitting and receiving signals;
a plurality of addressable transponders in a seismic cable;means for forming a code of digital bits of a data word for transmission to the addressable transponders; said plurality of addressable transponders comprising means responsive to the code transmitted from said transceiver. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A spread spectrum telemetry transmitter, for transmitting signals to a plurality of addressable transponders in a seismic cable, comprising:
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means for forming a code of digital bits of a data word composed of a distinctive frequency burst for such bits for transmission; and means for forming a code of further digital bits of the data word composed of a distinctive time spacing between such discrete frequency bursts. - View Dependent Claims (11, 12)
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13. A spread spectrum telemetry transponder in a seismic cable, comprising:
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means responsive to a code of digital bits of a received data word composed of a distinct frequency burst for such bits; and means responsive to a code of digital bits of the received data word composed of a distinctive time spacing between the discrete frequency bursts. - View Dependent Claims (14, 15, 16)
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Specification