Robust low-frequency spread-spectrum navigation system
First Claim
Patent Images
1. A method comprising:
- providing a plurality of radiolocation transmitters for a desired coverage area;
locking the plurality of radiolocation transmitters to a common timing reference;
transmitting a radiolocation signal, using a hybrid spread spectrum waveform that combines a direct sequence modulation with a frequency hopping, a time hopping, or a time gating protocol, from each of the plurality of radiolocation transmitters; and
sequentially turning off or reducing output power for a first radiolocation transmitter of the plurality of radiolocation transmitters in an inverse pulse time sequence that turns off or reduces the output power of the first radiolocation transmitter for a minority portion of a total data-cycle period and applies a standard output power for a majority portion of the total data-cycle period.
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Abstract
Methods and apparatus are described for a navigation system. A process includes providing a plurality of transmitters distributed throughout a desired coverage area; locking the plurality of transmitters to a common timing reference; transmitting a signal from each of the plurality of transmitters. An apparatus includes a plurality of transmitters distributed throughout a desired coverage area; wherein each of the plurality of transmitters comprises a packet generator; and wherein the plurality of transmitters are locked to a common timing reference.
68 Citations
41 Claims
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1. A method comprising:
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providing a plurality of radiolocation transmitters for a desired coverage area; locking the plurality of radiolocation transmitters to a common timing reference; transmitting a radiolocation signal, using a hybrid spread spectrum waveform that combines a direct sequence modulation with a frequency hopping, a time hopping, or a time gating protocol, from each of the plurality of radiolocation transmitters; and sequentially turning off or reducing output power for a first radiolocation transmitter of the plurality of radiolocation transmitters in an inverse pulse time sequence that turns off or reduces the output power of the first radiolocation transmitter for a minority portion of a total data-cycle period and applies a standard output power for a majority portion of the total data-cycle period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 36, 37)
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15. A method comprising:
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providing a plurality of radiolocation transmitters for a desired coverage area; locking the plurality of radiolocation transmitters to a common timing reference; transmitting a radiolocation signal, using a spread-spectrum waveform, from each of the plurality of radiolocation transmitters; turning off or reducing an output power of a first radiolocation transmitter of the plurality of radiolocation transmitters during a first time period; resuming standard output power for the first radiolocation transmitter during a second time period; turning off or reducing an output power of a second radiolocation transmitter of the plurality of radiolocation transmitters during the second time period; and sequentially turning off or reducing output power for the first radiolocation transmitter in an inverse pulse time sequence that turns off or reduces the output power of the first radiolocation transmitter for a minority portion of a total data-cycle period and applies the standard output power for a majority portion of the total data-cycle period; where during the first time period, the first radiolocation transmitter is turned off or has its output power reduced while multiple other radiolocation transmitters of the plurality of radiolocation transmitters transmit at a standard output power to allow a radiolocation receiver to acquire a fix with the multiple other radiolocation transmitters. - View Dependent Claims (16, 17, 18, 19)
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20. A method comprising:
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providing a plurality of radiolocation transmitters for a desired coverage area; locking the plurality of radiolocation transmitters to a common timing reference; transmitting a ground wave radiolocation signal, using a spread-spectrum waveform, from each of the plurality of radiolocation transmitters; and sequentially turning off or reducing output power for a first radiolocation transmitter of the plurality of radiolocation transmitters in an inverse pulse time sequence that turns off or reduces the output power of the first radiolocation transmitter for a minority portion of a total data-cycle period and applies a standard output power for a majority portion of the total data-cycle period. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 38)
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31. A method comprising:
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providing a plurality of radiolocation transmitters for a desired coverage area; locking the plurality of radiolocation transmitters to a common timing reference; transmitting a radiolocation signal, using a frequency hopping protocol and a spread-spectrum waveform, from each of the plurality of radiolocation transmitters; and sequentially turning off or reducing output power for a first radiolocation transmitter of the plurality of radiolocation transmitters in an inverse pulse time sequence that turns off or reduces the output power of the first radiolocation transmitter for a minority portion of a total data-cycle period and applies a standard output power for a majority portion of the total data-cycle period. - View Dependent Claims (32, 33, 34, 35, 39)
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40. A method comprising:
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providing a plurality of radiolocation transmitters for a desired coverage area; locking the plurality of radiolocation transmitters to a common timing reference; and transmitting a radiolocation signal, using a hybrid spread spectrum waveform that combines a direct sequence modulation with a frequency hopping, a time hopping, or a time gating protocol, from each of the plurality of radiolocation transmitters; where the act of transmitting the radiolocation signal comprises splitting the radiolocation signal into an 80-90 kHz band and a 110-120 kHz band.
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41. A method comprising:
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providing a plurality of radiolocation transmitters for a desired coverage area; locking the plurality of radiolocation transmitters to a common timing reference; and transmitting a ground wave radiolocation signal, using a spread-spectrum waveform, from each of the plurality of radiolocation transmitters; where the act of transmitting the radiolocation signal comprises splitting the radiolocation signal into an 80-90 kHz band and a 110-120 kHz band.
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Specification