Communication system and method
First Claim
1. A method of preventing effective communication between stations otherwise capable of communicating with each other and located more than a selected distance from each other, at least one of said stations including receiver means responsive to energy transmitted from the other station, comprising the steps of transmitting a first pulse to said stations from a position remote from said stations so that the first pulse arrives at said stations at substantially the same time, transmitting a second pulse from the other station upon receipt of said first pulse, receiving the first pulse at said one station, enabling the receiver means in response to receipt of said first pulse at said one station, and decoupling a portion of the receiver means after receipt of the first pulse at the one station, the time of decoupling being determined by the selected distance and the propagation time of the energy between the stations.
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Accused Products
Abstract
An aircraft collision avoidance system and method involves transmitting a stable reference frequency from a synchronous satellite to aircraft in a region being monitored. Each aircraft in the region receives the reference frequency and transmits a carrier, modulated with the received reference frequency, to other aircraft in a collision avoidance zone. At the other aircraft, an indication of impending collision is provided by measuring the rate of change of the carrier Doppler frequency shift received thereby from the first named aircraft. Sync pulses periodically modulate the reference frequency transmitted from the satellite for aircraft ranging and data control purposes. To limit the collision warning zone relative to each aircraft, the receiver thereof is deactivated at a predetermined time after each sync pulse is received from the satellite.
13 Citations
37 Claims
- 1. A method of preventing effective communication between stations otherwise capable of communicating with each other and located more than a selected distance from each other, at least one of said stations including receiver means responsive to energy transmitted from the other station, comprising the steps of transmitting a first pulse to said stations from a position remote from said stations so that the first pulse arrives at said stations at substantially the same time, transmitting a second pulse from the other station upon receipt of said first pulse, receiving the first pulse at said one station, enabling the receiver means in response to receipt of said first pulse at said one station, and decoupling a portion of the receiver means after receipt of the first pulse at the one station, the time of decoupling being determined by the selected distance and the propagation time of the energy between the stations.
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5. A method of warning the operator of a vehicle of intruding vehicles comprising the steps of:
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transmitting synchronizing signals from a satellite to said vehicles; receiving said synchronizing signals by each of said vehicles; transmitting response signals by each of said vehicles in response to said synchronizing signals; opening a receiving gate in each of said vehicles for said response signal, in response to said synchronizing signals; and
,closing said receiving gate after a predetermined period of time to prevent the passage through said gate of any response signals that are received after said predetermined period of time has passed. - View Dependent Claims (6, 7, 8)
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9. Apparatus for warning the operator of a vehicle of intruding vehicles comprising:
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a satellite, said satellite transmitting synchronizing signals to said vehiclle; receiving means located onboard each of said vehicles for receiving said synchronizing signals; transmitting means located onboard each of said vehicles for transmitting a response signal in response to said synchronizing signal; and receiving gate means located onboard each of said vehicles for receiving response signals from other vehicles, said receiving gate means including a gate for passing said response signals, said gate being open for a predetermined period of time in response to received synchronizing signals to allow the passage of response signals and closed after said predetermined period of time has elapsed to prevent the passage of any response signals received after said predetermined period of time has elapsed. - View Dependent Claims (10, 11, 12)
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13. Apparatus mountable onboard a vehicle for warning the operator of the vehicle of intruding vehicles comprising:
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receiving means receiving synchronizing signals from a satellite; transmitting means for transmitting a response signal in response to said synchronizing signal; and
,receiving gate means for receiving response signals from other vehicles, said receiving gate means including a gate for passing said response signals, said gate being open for a predetermined period of time in response to received synchronizing signals to allow the passage of response signals and closed after said predetermined period of time has elapsed to prevent the passage of any response signals received after said predetermined period of time has elapsed. - View Dependent Claims (14, 15, 16)
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17. A method of warning the operator of a first vehicle of an intruding vehicle comprising the steps of:
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transmitting synchronizing signals from a satellite to said vehicles; receiving said synchronizing signals by each of said vehicles; transmitting response signals by each of said vehicles in response to said synchronizing signals; opening a receiving gate in said first vehicle for said response signal, in response to said synchronizing signals; and
,closing said receiving gate after a predetermined period of time to prevent the passage through said gate of any response signals that are received after said predetermined period of time has passed. - View Dependent Claims (18)
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19. Apparatus for warning the operator of a first vehicle of an intruding vehicle comprising:
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a satellite , said satellite transmitting synchronizing signals to said vehicles; receiving means located onboard each of said vehicles for receiving said synchronizing signals; transmitting means located onboard each of said vehicles for transmitting a response signal in response to said synchronizing signal; and receiving gate means located onboard said first vehicle for receiving response signals from an intruding vehicle, said receiving gate means including a gate for passing said response signals, said gate being open for a predetermined period of time in response to received synchronizing signals to allow the passage of response signals and closed after said predetermined period of time has elapsed to prevent the passage of any response signals received after said predetermined period of time has elapsed. - View Dependent Claims (20)
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21. Apparatus mountable onboard a first vehicle for warning the operator of the vehicle of an intruding vehicle comprising:
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receiving means receiving synchronizing signals from a satellite; transmitting means for transmitting a response signal in response to said synchronizing signal; and
,receiving gate means for receiving response signals from an intruding vehicle, said receiving gate means including a gate for passing said response signals, said gate being open for a predetermined period of time in response to received synchronizing signals to allow the passage of response signals and closed after said predetermined period of time has elapsed to prevent the passage of any response signals received after said predetermined period of time has elapsed. - View Dependent Claims (22)
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- 23. A method of signalling only between stations within a predetermined distance of each other comprising the steps of transmitting a radio wave having a synchronizing signal modulated thereon from a point via line-of-sight communication links to each of the stations, said point and stations being positioned so that the synchronizing signal is effectively received at each station at substantially the same time, in response to receipt of the synchronizing signal at each station initiating line-of-sight transmission of second radio waves between the stations, and responding at one of said stations to said second waves only for a predetermined time interval after receipt of the signal at said one station, said interval being initiated by receipt at said one station of the synchronizing signal, said time interval being determined by the propagation velocity of said waves between the stations and the predetermined distance.
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26. A method of signalling only between stations within a predetermined distance of each other comprising the steps of transmitting a wave having a synchronizing signal modulated thereon from a point to each of the stations in such a manner that the synchronizing signal is effectively received at each station at substantially the same time, in response to receipt of the synchronizing signal at each station initiating line-of-sight transmission of second waves between the stations, and responding at one of said stations to said second waves only for a predetermined time interval after receipt of the signal at said one station, said interal being initiated by receipt at said one station of the synchronizing signal, said time interval being determined by the propagation velocity of said waves between the stations and the predetermined distance.
- 27. In a cooperative vehicle warning method for enabling vehicles only within a predetermined distance of each other to communicate with each other, the steps of transmitting a radio wave having a synchronizing signal modulated thereon from a point via line-of-sight communication links to each of the vehicles, said point and vehicles being positioned so that the synchronizing signal is effectively received at each station at substantially the same time, in response to receipt of the synchronizing signal at each vehicle initiating line-of-sight transmission of second radio waves between the vehicles, in response to receipt of the synchronizing signal at one vehicle enabling a receiver at the one vehicle to become responsive to the second radio waves transmitted from other vehicles, and in response to the passage of a predetermined elapsed time interval after receipt of the synchronizing signal at said one vehicle preventing the receiver at said one vehicle from being responsive to the second radio waves transmitted from other vehicles, said time interval being determined by the propagation velocity of radio waves between the vehicles and the predetermined distance.
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30. In a cooperative vehicle warning method for enabling vehicles only within a predetermined distance of each other to communicate with each other, the steps of transmitting a radio wave having a synchronizing signal modulated thereon from a point to each of the vehicles in such a manner that the synchronizing signal is effectively received at each station at substantially the same time, in response to receipt of the synchronizing signal at each vehicle initiating line-of-sight transmission of second radio waves between the vehicles, in response to receipt of the synchronizing signal at one vehicle enabling a receiver at the one vehicle to become responsive to the second radio waves transmitted from other vehicles, and in response to the passage of a predetermined elapsed time interval after receipt of the synchronizing signal at said one vehicle preventing the receiver at said one vehicle from being responsive to the second radio waves transmitted from other vehicles, said time interval being determined by the propagation velocity of radio waves between the vehicles and the predetermined distance.
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31. Apparatus adapted to be mounted on a vehicle in a cooperative vehicle warning system for enabling vehicles only within a predetermined distance of each other to communicate with each other, said system including means for transmitting a first radio wave having a synchronizing signal modulated thereon from a point to each of the vehicles in such a manner that the synchronizing signal is received at each of the vehicles at substantially the same time, the apparatus on the vehicle comprising:
- means for receiving the first radio wave, means for receiving via a line-of-sight communication link a second radio wave transmitted from another vehicle, the second radio wave being transmitted from the another vehicle in response to receipt at the another vehicle of the synchronizing signal, means responsive to receipt of the synchronizing signal for initiating transmission of a radio wave to the another vehicle, and means responsive to receipt of the synchronizing signal for enabling the receiving means for the second radio wave only for a predetermined elapsed time interval after receipt of the synchronizing signal, said time interval being determined by the propagation velocity of radio waves between the vehicles and the predetermined distance.
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32. A cooperative vehicle warning system for enabling vehicles only within a predetermined distance of each other to communicate with each other comprising means for transmitting a first radio wave having a synchronizing signal modulated thereon from a point via line-of-sight communication links to each of the vehicles, said point and vehicles being positioned so that the synchronizing signal is received at each of the vehicles at substantially the same time, apparatus on one of the vehicles comprising:
- means for receiving the first radio wave, means for receiving via a line-of-sight link a second radio wave transmitted from another vehicle;
apparatus on the another vehicle including means for transmitting the second radio wave in response to receipt at the another vehicle of the synchronizing signal;
the apparatus on the one vehicle further including;
means responsive to receipt of the synchronizing signal for initiating transmission of a radio wave to the another vehicle, and means responsive to receipt of the synchronizing signal for enabling the receiving means for the second radio wave only for a predetermined elapsed time interval after receipt of the synchronizing signal, said time interval being determined by the propagation velocity of said waves between the vehicles and the predetermined distance. - View Dependent Claims (33, 34)
- means for receiving the first radio wave, means for receiving via a line-of-sight link a second radio wave transmitted from another vehicle;
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35. A cooperative vehicle warning system for enabling vehicles only within a predetermined distance of each other to communicate with each other comprising means for transmitting a first wave having a synchronizing signal modulated thereon from a point to each of the vehicles in such a manner that the synchronizing signal is received at each of the vehicles at substantially the same time, apparatus on one of the vehicles comprising:
- means for receiving the first wave, means for receiving via a line-of-sight link a second wave transmitted from another vehicle;
apparatus on the another vehicle including means for transmitting the second wave in response to receipt at the another vehicle of the synchronizing signal;
the apparatus on the one vehicle further including;
means responsive to receipt of the synchronizing signal for initiating transmission of a wave to the another vehicle, and means responsive to receipt of the synchronizing signal for enabling the receiving means for the second wave only for a predetermined elapsed time interval after receipt of the synchronizing signal, said time interval being determined by the propagation velocity of said waves between the vehicles and the predetermined distance.
- means for receiving the first wave, means for receiving via a line-of-sight link a second wave transmitted from another vehicle;
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36. Apparatus at a station in a communication system with a vehicle within only a predetermined distance of the station, said system including means for transmitting a first radio wave having a synchronizing signal modulated thereon from a point to the station and vehicles in such a manner that the synchronizing signal is received at the station and vehicle at substantially the same time, the apparatus at the station comprising:
- means for receiving the first radio wave, means for receiving via a line-of-sight communication link a second radio wave transmitted from the vehicle, the second radio wave transmitted from the vehicle being initiated on the vehicle in response to receipt at the vehicle of the synchronizing signal, means responsive to receipt of the synchronizing signal for initiating transmission of a radio wave to the vehicle, and means responsive to receipt of the synchronizing signal for enabling the receiving means for the second radio wave only for a predetermined elapsed time interval after receipt of the synchronizing signal, said time interval being determined by the propagation velocity of said waves between the station and vehicle and the predetermined distance.
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37. A communication system between a station and a vehicle within only a predetermined distance of the station comprising means for transmitting a first radio wave having a synchronizing signal modulated thereon from a point via line-of-sight communication links to the station and vehicles, said point, station and vehicles being positioned so that the synchronizing signal is received at the station and vehicles at substantially the same time;
- apparatus at the station comprising;
means for receiving the first radio wave, means for receiving via line-of-sight link a second radio wave transmitted from a vehicle;
apparatus on the vehicle including means for initiating transmission of the second radio wave in response to receipt at the vehicle of the synchronizing signal;
said station further including;
means responsive to receipt of the synchronizing signal for initiating transmission of a radio wave to the vehicle, and means responsive to receipt of the synchronizing signal for enabling the receiving means for the second radio wave only for a predetermined elapsed time interval after receipt of the synchronizing signal, said time interval being determined by the propagation velocity of said waves between the station, vehicle and the predetermined distance.
- apparatus at the station comprising;
Specification