Radio navigation receiving equipment

Claim 2

A radio navigation system having a physically fixed transmitting station programmed to radiate a first radiofrequency energy signal from a first antenna and a reference radiofrequency signal from a second antenna, including means for commutating energy among the elements of said first antenna to simulate rectilinear radiating source motion at substantially constant velocity, comprising the combination of: receiving means responsive to said first and reference radio signals at a remote mobile station, for generating direction and distance signals, the frequencies of said direction and distance signals being a function of the Doppler shift of said first signal due to said commutation and representing the direction and distance of said mobile station from said transmitting station; and track computing means responsive to said direction and distance signals over a first predetermined range of values of said direction and distance signals, for defining at least a non-radial track with respect to said transmitting station.

Claim 3

Apparatus according to claim 1 in which said track computing means is further defined as also being responsive to said direction and distance signals over a second predetermined range of values of said direction and distance signals, for defining a radial track with respect to said transmitting station.

Claim 4

Apparatus according to claim 2 including means for indicating any departure of said mobile station from said non-radial or said radial tracks.

Claim 5

Apparatus according to claim 3 including means for controlling said track computing means such that, during approach of said mobile station toward said transmitting station, to change from said non-radial to said radial track at a predetermined distance from said transmitting station, said predetermined distance constituting a track inflection point.

Claim 6

Apparatus according to claim 4 in which said track computing means comprises; a first counter responsive to said received distance signal to produce a first analog output signal of amplitude proportional to the frequency of said distance signal, an amplifier for amplifying said first analog output signal by a factor which is a function of the distance from said transmitting station to said inflection point, first selector means responsive to said direction signal for producing a second analog output signal of polarity opposite that of said first analog output signal and having an amplitude proportional during said non-radial track to the frequency of said direction signal, an adder for adding said first and second analog output signals, second selector means for producing a third analog output signal of polarity opposite that of said second analog output signal and with amplitude proportional during said radial track to the frequency of said direction signal, and means responsive to the outputs of said adder and said second selector to change said track from non-radial to radial definition at said inflection point.

Claim 7

Apparatus according to claim 2 in which said defined track is a glide path.

Claim 8

Apparatus according to claim 2 in which said defined track is a runway azimuth approach path.

Claim 9

Apparatus according to claim 6 in which said transmitting station includes a single vertical antenna array of equally spaced elements excited by energy commutated among said elements, two separate receiving antennas spaced in the vertical plane are provided at said mobile station, means operative with one of said receiving antennas for determining the elevation angle of said mobile station, and means operative with both of said receiving antennas for determining the distance of said mobile station.

Claim 10

Apparatus according to claim 6 in which said transmittIng station includes a vertical antenna array of equally spaced elements and a horizontal array of equally spaced elements, means for supplying energy commutated among said elements of both arrays, two separate receiving antennas spaced in the horizontal plane at said mobile station, means operative with one of said receiving antennas for determining the angle of elevation of said mobile station from the frequency of energy radiated by said vertical array, and means operative with both of said receiving antennas for determining the distance of said mobile station from the frequency of energy radiated by said horizontal array.

Claim 11

Apparatus according to claim 6 in which said transmitting station includes; a vertical array of equally spaced elements and two in-line horizontal arrays of equally spaced elements, means for exciting said vertical array with commutated energy, means for exciting both of said horizontal arrays with unidirectionally commutated energy; and said mobile station includes a single receiving antenna associated with means for determining the angle of elevation of said mobile station from the frequency of energy radiated by said vertical array, and means for determining the distance of said mobile station from the frequency of energy radiated by said two horizontal arrays.

Claim 12

Apparatus according to claim 7 in which said transmitting station has two in-line horizontal arrays of equally spaced elements extending normally on either side of the runway, means are included for exciting both of said horizontal arrays with unidirectionally commutated energy; and in which said mobile station includes a single receiving antenna associated with means for determining both distance and bearing of said mobile station from the frequency of energy radiated by both of said arrays.