Precision landing system
OwnerEdward W. Heinzerlinginventor
Life of this patent
Estimating the term…
Abstract
An aircraft landing system employs an array of antennas aligned across the runway, and equipment on board the aircraft employs radio interferometry to measure path length differences between the aircraft and selected pairs of the antennas. The antennas each include circuitry for sideband modulation of a basic FM signal so that each antenna radiates a pair of sidebands displaced above and below the basic signal by a respective number of increments. The FM signal can be carried on an X-band carrier of nominally ten GHz, with a frequency deviation of .+-.250 MHz and a modulating frequency of 20 Hz. Further antennas provide taxiing guidance. Data can be communicated on the system.
Claims20
High precision radio interferometry arrangement to guide an aircraft to a runway during a landing maneuver, comprising:
- a plurality of antennas, including a first antenna and a second antenna disposed at respective locations at a predetermined distance along said runway and a predetermined elevation thereabove, and spaced at predetermined distances at opposite sides of the runway;
- a master transmitter associated with the first antenna and which provides same with a frequency modulated signal in which a continuous wave rf carrier at a predetermined center frequency is modulated by a modulating signal having a predetermined modulating frequency and in which the frequency modulated signal has a predetermined frequency deviation, including sideband modulating means providing a pair of sideband signals which track the master transmitter modulated signal in frequency and phase, the pair of sideband signals being disposed symmetrically above and below the master transmitter signal and being separated therefrom by a first frequency offset;
- a slave transmitter associated with said second antenna and providing same with a second pair of frequency modulated sideband signals, including a second sideband modulating means providing said second pair of sideband signals which track the master transmitter modulated signal in frequency and phase, the pair of sideband signals being disposed symmetrically above and below the master transmitter signal and being separated therefrom by a second frequency offset which is unique to said second sideband modulating means;
- synchronizing means for synchronizing said master transmitter and said slave transmitter, so that said sideband carriers and said modulating signal are in synchronism at said transmitters;
- and
- an airborne receiver situated in each of one or more aircraft for receiving the signals emitted by the first and second antennas, including means for demodulating the respective signals to a common frequency, and means for phase-comparing the demodulated signals from the respective antennas and for deriving accurate positioning information for said aircraft.
High precision radio interferometry arrangement to guide an aircraft while on the ground comprising:
- a plurality of antennas, including at least a first antenna and a second antenna disposed at respective first and second locations at said airport;
- a master transmitter associated with the first antenna and which provides same with a frequency modulated signal in which a continuous wave rf carrier at a predetermined center frequency is modulated by a modulating signal having a predetermined modulating frequency and in which the frequency modulated signal has a predetermined frequency deviation, including sideband modulating means providing a pair of sideband signals which track the master transmitter modulated signal in frequency and phase, the pair of sideband signals being disposed symmetrically above and below the master transmitter signal and being separated therefrom by a first frequency offset;
- a slave transmitter associated with said second antenna and providing same with a second pair of frequency modulated sideband signals, including a second sideband modulating means providing said second pair of sideband signals which track the master transmitter modulated signal in frequency and phase, the pair of sideband signals being disposed symmetrically above and below the master transmitter signal and being separated therefrom by a second frequency offset which is unique to said second sideband modulating means;
- synchronizing means for synchronizing said master transmitter and said slave transmitter so that, said sideband signals and said modulating signal are in synchronism at said transmitters;
- and
- a receiver situated in each of one or more aircraft for receiving the signals emitted by the first and second antennas, including means for demodulating the respective signals to a common frequency, and means for phase-comparing and demodulating signals from the respective antennas and for deriving accurate positioning information for said aircraft.
Dependencies are inferred from the claim text.