Position indicating system
First Claim
1. A position indicating system including a population of simultaneously participating movable stations, each station knowing its geographic position through the reception of signals from a plurality of geometrically distributed transmitters having known positions, each participating station having a transmitter for the emission in a common radio channel, of signals indicating its own geographic position, memory means being arranged for the memorization of received information from other participating stations, wherein each movable station hasa) a time base common to all of said movable stations, said time base being accurately controlled by time signals from said plurality of geometrically distributed transmitters, and defining time blocks which are standardized, enumerable and form a common, accurate, repeating maximal frame of known length,b) means for occupying a free time block in each maximal frame and for autonomously transmitting therein of a position signal in the common radio channel.
1 Assignment
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Reexamination
Accused Products
Abstract
A plurality of movable objects, such as aircraft, are provided with GPS receivers, enabling the individual determination of longitude and latitude. Further, the receiver also receives a very precise time base from the GPS satellites. This very precise time base is used to enable all of the plurality of movable objects to transmit in a predetermined radio frequency their identities and positions in precisely determined time blocks. By limiting the range of the frequencies used by the movable objects to transmit, the range of receivability is limited, such that the system may be implemented as a worldwide overlapping mosaic. The transmissions of each movable object may be received by all of the plurality of movable objects, as well as by air traffic monitoring centers on the ground.
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Citations
13 Claims
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1. A position indicating system including a population of simultaneously participating movable stations, each station knowing its geographic position through the reception of signals from a plurality of geometrically distributed transmitters having known positions, each participating station having a transmitter for the emission in a common radio channel, of signals indicating its own geographic position, memory means being arranged for the memorization of received information from other participating stations, wherein each movable station has
a) a time base common to all of said movable stations, said time base being accurately controlled by time signals from said plurality of geometrically distributed transmitters, and defining time blocks which are standardized, enumerable and form a common, accurate, repeating maximal frame of known length, b) means for occupying a free time block in each maximal frame and for autonomously transmitting therein of a position signal in the common radio channel.
- 10. A positioning station for a position indicating system comprising a GNSS signal receiver arranged to deliver a geographic position at the station, and a transceiver for transmitting said geographic position in a radio channel, a communication processor (5) connected to said satellite signal receiver (4), and to said transceiver, said radio channel being of a frequency having a physically limited range, said communication processor comprising a time base (13), a time synchronization connection between the time base and the satellite receiver, a microprocessor (10), a RAM memory (11) for collecting position signals received by the transceiver in time blocks determined by the time base, a program memory (12), a data bus (14), an address bus (15), means for accounting of position messages received from neighbouring stations and taken from said RAM memory, and means for transmitting in an autonomous mode own position signals to said transceiver of their transmission in time blocks unoccupied by other stations.
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13. A position indicating system including a first population of movable stations and a second population of geographically fixed stations with known geographic locations, each participating station having a receiver for receiving signals from a plurality of satellites provided for determining geographic location, and means for calculating therefrom a geographic location, said satellite signals being provided with time jitters limiting precision of said determined location,
a) each said fixed station having access to a time base common to all said fixed stations, said time base defining time blocks forming a common, accurate, and repeating maximal frame, b) each said fixed station having means for occupying a time block in each maximal frame not occupied by another station, a transmitter for transmitting in said time block in a common radio channel whose frequency is such that its range of detection is substantially limited to the line of sight, and means for transmitting by said transmitter in said time block of information comprising longitude and latitude information, and correction information obtained by comparing its known geographic position to said calculated location, said correction information comprising compensation for said jitter and for varying atmospheric conditions of reception of satellite signals at the location of the fixed station, c) each said movable station having a receiver for receiving signals in said time blocks of said common radio channel, means for comparing its own geographic location as determined from said satellite signals to geographic location information received in said time slots from a plurality of fixed stations and for selecting one thereof, and compensating its calculated geographic location using said correction information received from said selected fixed station.
Specification