US3742503A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air traffic control systems
Assignee: SECR DEFENCE
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Filing: 1971-05-19
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Granted: 1973-06-26
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Expires: 1991-05-19
Abstract
Abstract An air traffic headway control system comprises a ground transmitter located en route and a receiver in each aircraft. The transmitter transmits cyclic sequences of distinctive signals whose timing is controlled by a highly stable master oscillator. These are received in the aircraft which also has a stable oscillator synchronized to the master oscillator of the transmitter. Reference pulses which are timed with respect to the stable oscillator are generated in the receiver and a comparison is made between the timing of the reference pulses and the time of reception of the sequences of distinctive signals to provide an indication of the position of the aircraft in the lane. A perturbation is applied to the timing of the beginning of each sequence which represents the desired motion of the aircraft. The receiver also includes means for controlling the speed of the aircraft in accordance with its indicated position so as to maintain or correct its position. The means for making the comparison in timing preferably includes a correlation detector.
Inventors
- 👤 A Stratton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 04:09
CPC Classifications
G; G01; G01S; G01S11/00; G01S11/02; G01S11/08
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
198 words
An air traffic headway control system comprising; transmitter apparatus at a fixed ground station, said transmitter apparatus including a first stable oscillator and means for transmitting cyclic sequences of distinctive signals at times determined with respect to the first stable oscillator, each sequence beginning with a predetermined, distinctive signal and comprising a plurality of distinctive signal transitions in a predetermined sequence; receiver apparatus in each aircraft using the system, said receiver apparatus including a second stable oscillator, means for receiving the said sequences of distinctive signals, means for generating reference pulses at times determined with respect to the second stable oscillator, and comparison means for measuring differences between the timing of the reference pulses and the time of reception of a transition in each of the said sequences of distinctive signals; and perturbation means in one of said transmitter and receiver apparatus for causing displacements in the relative timing of the transmitted signals and the receiver reference pulses, said perturbation means including means operative to increase said displacements in successive sequences in a predetermined manner related to the desired progress of the aircraft, and for resetting and restarting said displacements from zero after a predetermined number of sequences.
Claim 2
Dependent Claim
198 words
An air traffic headway control system comprising; transmitter apparatus at a fixed ground station, said transmitter apparatus including a first stable oscillator and means for transmitting cyclic sequences of distinctive signals at times determined with respect to the first stable oscillator, each sequence beginning with a predetermined, distinctive signal and comprising a plurality of distinctive signal transitions in a predetermined sequence; receiver apparatus in each aircraft using the system, said receiver apparatus including a second stable oscillator, means for receiving the said sequences of distinctive signals, means for generating reference pulses at times determined with respect to the second stable oscillator, and comparison means for measuring differences between the timing of the reference pulses and the time of reception of a transition in each of the said sequences of distinctive signals; and perturbation means in one of said transmitter and receiver apparatus for causing displacements in the relative timing of the transmitted signals and the receiver reference pulses, said perturbation means including means operative to increase said displacements in successive sequences in a predetermined manner related to the desired progress of the aircraft, and for resetting and restarting said displacements from zero after a predetermined number of sequences.
Claim 3
Dependent Claim
118 words
Transmitter apparatus for an air traffic headway control system, including a first stable oscillatoR, means for transmitting cyclic sequences of distinctive signals at times determined with respect to the first stable oscillator, each sequence beginning with a predetermined distinctive signal and comprising a plurality of distinctive signal transitions in a predetermined sequence, and perturbation means for causing displacements in the timing, with respect to the first stable oscillator, of the beginning and the transitions of the sequences, said perturbation means including means operative to increase said displacements in successive sequences in a predetermined manner related to the desired progress of the aircraft and to reset and restart said displacements from a zero after a predetermined number of sequences.
Claim 4
Dependent Claim
118 words
Transmitter apparatus for an air traffic headway control system, including a first stable oscillatoR, means for transmitting cyclic sequences of distinctive signals at times determined with respect to the first stable oscillator, each sequence beginning with a predetermined distinctive signal and comprising a plurality of distinctive signal transitions in a predetermined sequence, and perturbation means for causing displacements in the timing, with respect to the first stable oscillator, of the beginning and the transitions of the sequences, said perturbation means including means operative to increase said displacements in successive sequences in a predetermined manner related to the desired progress of the aircraft and to reset and restart said displacements from a zero after a predetermined number of sequences.
Claim 5
Dependent Claim
36 words
Transmitter apparatus as claimed in claim 2 wherein the perturbation means is constructed to cause the said time displacements to be increased by like successive terms of an arithmetic progression, over a predetermined number of sequences.
Claim 6
Dependent Claim
120 words
Receiver apparatus for an air traffic headway control system, including a stable oscillator, receiver means for receiving signals transmitted from a ground station, means for measuring the time delay td between the occurrence of a pulse at the output of the stable oscillator and the reception of a first distinctive signal from the ground station, means for generating a reference pulse at a time delayed, by a time dependent on the measured time td, after the reception of the said first distinctive signal, and means for deriving a control signal dependent on the timing relative to the reference pulse of the reception of a distinctive feature of the signals transmitted from the ground station and received by the receiver means.
Claim 7
Dependent Claim
120 words
Receiver apparatus for an air traffic headway control system, including a stable oscillator, receiver means for receiving signals transmitted from a ground station, means for measuring the time delay td between the occurrence of a pulse at the output of the stable oscillator and the reception of a first distinctive signal from the ground station, means for generating a reference pulse at a time delayed, by a time dependent on the measured time td, after the reception of the said first distinctive signal, and means for deriving a control signal dependent on the timing relative to the reference pulse of the reception of a distinctive feature of the signals transmitted from the ground station and received by the receiver means.
Claim 8
Dependent Claim
93 words
Receiver apparatus as claimed in claim 4 and wherein the said means for deriving the control signal includes a local oscillator controlled by the reference pulses so that it oscillates for the duration of each reference pulse, a multiplicative signal mixer connected to mix the signal of the local oscillator with modulation components of selected ones of the received distinctive signals so as to derive beat frequency signals therefrom, and a comparison means connected to produce an output representing the difference in magnitude and sign between selected ones of the beat frequency signals.
Claim 9
Dependent Claim
34 words
Receiver apparatus as claimed in claim 5, and also including means for measuring the Doppler frequency shift in the received signals and deriving from it a signal representing the relative velocity of the aircraft.
References Cited (Backward Citations)
US3336591A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |