Pulsed, pseudo random position fixing radio navigation method and system and the like
First Claim
1. A method of rendering multi-station radio-frequency pulse navigation relatively insensitive to inband interference, that comprises, transmitting groups of radio-frequency pulses from each station with a group repetition rate selected to enable transmission of a pulse group from each station with sufficient time between each pulse group that signals from two or more of the stations cannot overlap in time anywhere in the navigation coverage area;
- pseudo-randomly pulse-position modulating pulses within groups in accordance with a predetermined code and over a sufficiently large number of groups to insure that the resulting pseudo-random pulse sequence contains a sufficiently large number of pulses that adequate skywave-groundwave rejection of the transmitted pulse groups occurs everywhere the same are received in said navigation coverage area.
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Accused Products
Abstract
This disclosure is concerned with a technique and apparatus for reducing CW and other inband interference in a broad bandwidth RF pulse navigation system to inobtrusive noise through the use of pulse-position random modulation, including, where desired, superimposed random phase modulation, with signal-random modulation code cross-correlation in reception.
43 Citations
29 Claims
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1. A method of rendering multi-station radio-frequency pulse navigation relatively insensitive to inband interference, that comprises, transmitting groups of radio-frequency pulses from each station with a group repetition rate selected to enable transmission of a pulse group from each station with sufficient time between each pulse group that signals from two or more of the stations cannot overlap in time anywhere in the navigation coverage area;
- pseudo-randomly pulse-position modulating pulses within groups in accordance with a predetermined code and over a sufficiently large number of groups to insure that the resulting pseudo-random pulse sequence contains a sufficiently large number of pulses that adequate skywave-groundwave rejection of the transmitted pulse groups occurs everywhere the same are received in said navigation coverage area.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus for rendering multi-station radio-frequency pulse navigation relatively insensitive to inband interference, that comprises, a plurality of transmitter stations for transmitting groups of radio-frequency pulses from each transmitter station with a group repetition rate selected to enable transmission of a pulse group from each station with sufficient time between each pulse group that signals from two or more of the stations cannot overlap in time anywhere in the navigation coverage area of the plurality of stations;
- and means for effectively pseudo-randomly pulse-position modulating pulses within pulse groups at said stations in accordance with a predetermined code and over a sufficiently large number of groups to insure that the resulting pseudo-random pulse sequence contains a sufficiently large number of pulses that adequate skywave-groundwave rejection of the transmitted pulse groups occurs everywhere the same are received in said navigation coverage area.
- View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
- 22. For use with multi-station radio-frequency pulse navigation apparatus adapted to be relatively insensitive to inband interference and wherein groups of radio-frequency pulses are transmitted from each station with a group repetition rate selected to enable transmission of a pulse group from each station with sufficient time between each pulse group that signals from two or more of the stations cannot overlap in time anywhere in the navigation coverage area, and the pulses within said groups are pseudo-randomly pulse-position modulated in accordance with a predetermined code and over a sufficiently large number of groups to insure that the resulting pseudo-random pulse sequence contains a sufficiently large number of pulses that adequate skywave-groundwave rejection of the transmitted pulse groups occurs everywhere the same are received in said navigation coverage area, apparatus for reception of the transmitted pulses within said navigation coverage area comprising, means for receiving the transmitted pulses, means for cross-correlating the received signals with said predetermined code of pulse-position modulation, and means for transforming any inband interference and the like into random noise.
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27. For use with multi-station radio-frequency pulse apparatus adapted to be relatively insensitive to inband interference and wherein groups of radio-frequency pulses are transmitted from each station with a group repetition rate selected to enable transmission of a pulse group from each station with sufficient time between each pulse group that signals from two or more of the stations cannot overlap in time anywhere in the navigation coverage area, and the pulses within said groups are pseudo-randomly pulse-position modulated in accordance with a predetermined code and over a sufficiently large number of groups to insure that the resulting pseudo-random pulse sequence contains a sufficiently large number of pulses that adequate skywave-groundwave rejection of the transmitted pulse groups occurs everywhere the same are received in said navigation coverage area, a method of reception of the transmitted pulses within said navigation coverage area comprising, receiving said transmitted pulses, cross-correlating the received signals with said predetermined code of pulse-position modulation, and transforming any inband interference and the like into random noise.
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28. A method of rendering radio-frequency pulse transmissions relatively insensitive to inband interference, that comprises, transmitting groups of radio-frequency pulses with group repetition rates selected with sufficient time between each group that signals cannot overlap in time anywhere in the desired coverage area;
- pseudo-randomly pulse-position modulating pulses within groups in accordance with a predetermined code and over a sufficiently large number of groups to insure that the resulting pseudo-random pulse sequence contains a sufficiently large number of pulses that adequate skywave-groundwave rejection of the transmitted pulse groups occurs everywhere the same are received in said coverage area.
- View Dependent Claims (29)
Specification