Helicopter navigation system

Claim 2

A navigation system for a helicopter having a body provided with rotor blades turning about an axis of a rotor shaft, comprising: two antennas carried by said blades at points remote from said axis for receiving electromagnetic waves radiated by a beacon of predetermined location; processing means on said body including two generators of local oscillations, two mixers for respectively heterodyning received waves from said antennas with said local oscillations to produce two intermediate-frequency signals, nonlinear impedance means connected to said mixers for multiplying said intermediate-frequency signals with each other to produce a resulting signal, and detector means connected to said impedance means for deriving a phase-modulated output signal from said resulting signal; evaluation means connected to said detector means for correlating said output signal with a set of spatial coordinates; and integrating display means connected to said evaluation means for indicating the spatial coordinates associated with said output signal.

Claim 3

A navigation system as defined in claim 1 wherein said generators are local oscillators of different operating frequencies.

Claim 4

A navigation system as defined in claim 2 wherein said detector means includes a further mixer connected to said local oscillators for deriving therefrom a demodulating frequency constituting the mean of said operating frequencies.

Claim 5

A navigation system as defined in claim 3 wherein said mixers and said local oscillators are mounted on said blades, said detector means including a stationary nonlinear element connected to said further mixer and to said nonlinear impedance means through respective slip rings on said rotor shaft.

Claim 6

A navigation system as defined in claim 3 wherein said antennas are joined to said two mixers by respective connectors introducing a phaseshift of π/4 between said received waves.

Claim 7

A navigation system as defined in claim 3 wherein said evaluation means comprises a light source connected to said detector means for receiving therefrom said output signal, and a light modulator positioned for illumination by said light source, said light modulator having a light-transmissivity pattern substantially conforming to the phase modulation of said output signal.

Claim 8

A navigation system as defined in claim 6 wherein said integrating display means comprises a photoelectric transducer positioned for illumination by way of said light modulator.

Claim 9

A navigation system as defined in claim 6 wherein said light modulator comprises a rotatable disc driven by said rotor shaft in synchronism with said rotor blades.

Claim 10

A navigation system as defined in claim 8 wherein said disc has a surface divided into a multiplicity of parallel zones whose light transmissivity varies according to a periodic law from one zone to the next while being constant along each zone.

Claim 11

An airborne navigation system installed aboard a helicopter for obtaining positional information with reference to a beacon radiating electromagnetic waves, said helicopter having a body provided with rotor blades turning about an axis of a rotor shaft, comprising: two antennas carried by said blades at points remote from said axis for receiving electromagnetic waves radiated by said beacon; processing means connected to said antennas for deriving from the received waves an output signal with a direct-current component and with a phase modulation due to the rotation of said antennas about said axis; evaluation means connected to said processing means for correlating said output signal with a set of spatial coordinates, said evaluation means including a source of light modulated in intensity by said output signal and a rotary light modulator positioned for illumination by light from said source, said light modulator being synchronized with said rotor shaft and having a light-transmissivity pattern substantially conforming to the phase modulation of said output signal; and integrating display means connected to said evaluation means for indicating said position-defining values on a two-dimensional luminous field.

Claim 12

An airborne navigation system installed aboard a helicopter for obtaining positional information with reference to a beacon radiating electromagnetic waves, said helicopter having a body provided with rotor blades turning about an axis of a rotor shaft, comprising: two antennas carried by said blades at points remote from said axis for receiving electromagnetic waves radiated by said beacon; processing means connected to said antennas for deriving from the received waves an output signal with a direct-current component and with a phase modulation due to the rotation of said antennas about said axis; evaluation means connected to said processing means for correlating said output signal with a set of spatial coordinates, said evaluation means including a source of light modulated in intensity by said output signal and a rotary light modulator positioned for illumination by light from said source, said light modulator being synchronized with said rotor shaft and having a light-transmissivity pattern substantially conforming to the phase modulation of said output signal; and integrating display means connected to said evaluation means for indicating said position-defining values on a two-dimensional luminous field.

Claim 13

A navigation system as defined in claim 10 wherein said integrating display means comprises a photoelectric transducer positioned for illumination by said light modulator.

Claim 14

A navigation system as defined in claim 11 wherein said light modulator is a rotatable disc driven by said rotor shaft, said disc having a surface divided into a multiplicity of parallel zones whose light transmissivity varies according to a periodic law from one zone to the next while being constant along each zone.

Claim 15

A navigation system as defined in claim 10 wherein said processing means has two inputs joined to said antennas by respective connectors introducing a phaseshift between said received waves.