US 5,311,194 AGranted

GPS precision approach and landing system for aircraft

AssigneeNAVSYS Corporation

InventorAlison K. Brown

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Abstract

A GPS precision approach and landing system for aircraft employs a fixed ground facility and a single satellite navigation receiver on board the aircraft. The fixed ground facility includes a reference receiver that measures differential corrections to the satellite code and carrier measurements and a pseudolite that is employed to transmit these corrections to a broadband GPS receiver on board the aircraft and to provide an additional code and carrier measurement to assist in the navigation solution. The pseudolite signal is broadcast at a frequency offset from the L1 GPS frequency in order to prevent interference with the satellite navigation system. The broadband GPS receiver on board the aircraft is capable of making phase coherent measurements from the GPS satellites, the pseudolite signal, and the GLONASS satellites. These phase coherent measurements are combined to form a precise differential carrier ranging (DCR) solution that is used to provide three-dimensional position guidance of the aircraft throughout a precision approach and landing procedure.

Claims13

Dependent claims

A GPS precision approach and landing system for aircraft, the system comprising:

a pseudolite positioned at a fixed location on the ground, the pseudolite being operative for transmitting a pseudolite signal, the pseudolite signal including an assigned PRN code modulated on an L-band carrier signal having a frequency that is removed from an L1 GPS satellite frequency, the pseudolite signal being synchronized with GPS time by means of a GPS timing signal;
a GPS reference receiver positioned at a fixed location on the ground and coupled to the pseudolite, the GPS reference receiver being operative for tracking GPS satellite and pseudolite signals and for computing differential GPS correction information comprising both pseudo-range and carrier-range correction information from reference information defining the position of the GPS reference receiver;
the pseudolite being further operative for transmitting the computed differential GPS correction information computed by the GPS reference receiver to an aircraft performing a precision approach and landing procedure;
the GPS precision approach and landing system further comprising a single receiver positioned on the aircraft, said single receiver comprising a broadband GPS receiver operative for receiving the computed differential GPS correction information transmitted by the pseudolite and for performing phase coherent measurements of L1 GPS satellite signals and L-band pseudolite signals to determine the three-dimensional position of the aircraft with respect to an approach path associated with the precision approach and landing procedure.

1 more element

A method employing GPS satellites for determining the three-dimensional position of an aircraft performing a precision approach and landing, the method comprising:

providing a pseudolite positioned at a fixed location on the ground for transmitting a pseudolite signal, including an assigned PRN code, modulated on an L-band carrier signal having a frequency that is removed from an L1 GPS satellite frequency, the pseudolite signal being synchronized with GPS time;
providing a GPS reference receiver positioned at a fixed location on the ground, the GPS reference receiver being operative for tracking GPS satellite and pseudolite signals and for computing differential GPS correction information comprising both pseudo-range and carrier-range correction information from reference information defining the position of the GPS reference receiver;
transmitting, by means of the pseudolite, the computed differential GPS correction information computed by the GPS reference receiver to said aircraft;
providing a single receiver on said aircraft, said single receiver being a broadband GPS receiver operative for receiving the computed differential GPS correction information transmitted by the pseudolite and for performing phase coherent measurements of L1 GPS satellite signals and L-band pseudolite signals to determine the three-dimensional position of said aircraft.

1 more element

Dependencies are inferred from the claim text.