METHOD OF PREVENTING UNAUTHORISED USE OF AIRCRAFT Russian patent published in 2012 - IPC G08G5/00 B60R25/00 

FIELD: physics.

SUBSTANCE: in the method, during unauthorised operation of aircraft, a harmonic oscillation is generated on-board the aircraft at carrier frequency ω_c, and then phase-shift keyed with a pseudorandom sequence which is the identification number of the aircraft. The generated composite phase-shift keyed signal undergoes frequency conversion using a first heterodyne frequency ω_r1. Voltage of the first intermediate frequency, which is equal to the sum ω_pr1=ω_c+ω_r1 is picked up, power amplified and broadcast at frequency ω₁=ω_pr1=ω_r2. The phase-shift keyed signal at frequency ω₁ is received at the air-traffic control station. A harmonic oscillation at carrier frequency ω_c is generated at the air-traffic control station and then phase-shift keyed with a modulating code which displays commands for reconfiguration of the on-board equipment of the aircraft. A composite phase-shift keyed signal at frequency ω₁ is then received on-board the aircraft. Low-frequency voltage which is proportional to the modulating code is picked up and then used to reconfigure the on-board equipment of the aircraft. Heterodyne frequencies ω_r1 and ω_r2 are separated by a second intermediate frequency value ω_r2-ω_r1=ω_pr2.

EFFECT: high reliability of duplex radio communication between air-traffic control stations and aircraft.

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