Communications: directive radio wave systems and devices (e.g. – Directive – Beacon or receiver
Patent
1997-09-11
2000-08-29
Blum, Theodore M.
Communications: directive radio wave systems and devices (e.g.,
Directive
Beacon or receiver
342404, 342412, G01S 116, G01S 118
Patent
active
061115436
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a method and a device for analysing signals radiated by radio navigation stations, of the "ILS" and "VOR" type, for example, supplying values characteristic of elementary signals constituting the guidance information signals transmitted by said stations.
BACKGROUND OF THE INVENTION
"ILS" type stations comprise three sub-stations: to the runway axis, to a glide path, threshold.
The angular error information is measured from the difference of the depth of modulation (DDM) of two frequencies, 90 Hz and 150 Hz.
Standard or Doppler type "VOR" beacons supply information on the angular error relative to a reference tied to magnetic North. The angular error information is measured from the phase difference between a 30 Hz reference signal and a variable 30 Hz signal.
ILS and VOR beacons conform to international standards and specifications published by the International Civil Aviation Organisation (ICAO), and in particular in the documents known as "appendix 10" and "appendix 8071" volumes 1 and 2.
Radio navigation beacons (or stations) comprise a number of functional units. When associated with and adjusted to each other, these units supply guidance signals to aircraft.
The components of a beacon are as follows: other units, information signals, and radio-frequency signals, known as carrier signals. These L.F. and R.F. signals have pure sinusoidal waveforms, "generator" unit to the transmit antenna(s), one or more types of signals generated by the "generator" unit, the antennas. They are called couplers, nearfield sensors or farfield sensors. The sensors are associated ith a "recombine" unit, distributor and radiator units, for x channels, decide to shut down the station or to switch to a back-up transmitter.
The sensor, monitor and decision unit are responsible for the "monitoring" function monitoring the integrity of the signals transmitted.
The complexity of a system of this kind requires a high level of technical knowledge on the part of personnel responsible for using and maintaining it. This personnel is also required to use many measuring instruments.
Some of the parameters for diagnosing a fault or a variation in the information transmitted by the stations are inaccessible. For example: the phase and the amplitude of SBO signals, the frequency and amplitude error of the various transmitters forming part of the beacon.
Operators must intervene physically on the connections between the functional units, which necessarily interrupts the use of the beacon by aircraft, which reduces the availability of the beacon.
The signals transmitted by the beacons on one channel are made up of a plurality of sources called C+SB, meaning carrier and sidebands, and SBO, meaning sidebands only. These radio sources must be locked to a plurality of frequencies within the same channel. The beacons are typically single-frequency or dual-frequency beacons depending on the number of radio frequencies that they transmit.
The C+SB and SBO signals are generated by forming the product of the radio frequency signals with low frequency signals and a DC component, which constitutes amplitude modulation.
To give one, non-limiting example, the characteristic equation of the guidance signal x(t) radiated by an ILS type beacon can take the following form: sin(2.pi.*f2*t+.PHI.2)+m3 sin(2.pi.*f3*t)+m4 sin(2.pi.*f4*t)]+B*cos(2.pi.*F0*t+.PHI..sub.-- SBO0)*[m1' sin(2.pi.*f1*t)+m2' sin(2.pi.*f2*t+.PHI.2)]+C*cos(2.pi.*F1*t+.PHI..sub.-- CSB1)*[1+m1" sin(2.pi.*f1*t)+m2" sin(2.pi.*f2*t+.PHI.2)+m3" sin(2.pi.*f3*t)+m4" sin(2.pi.*f4*t)]+D*cos(2.pi.*F1*t+.PHI..sub.-- SBO1)*[m1'" sin(2.pi.*f1*t)+m2'" sin(2.pi.*f2*t+.PHI.2)] a phase .PHI..sub.-- CSB0, phase .PHI..sub.-- SBO0, a phase .PHI..sub.-- CSB1, phase .PHI..sub.-- SBO1, Hereinafter, Fn designates a radio frequency signal of any frequency, modulating the radio frequency signals F0, F1 and Fn. Hereinafter, fn designates a low frequency signal of any frequency, f1, generally f1=90 Hz for ILS and 30 Hz for VOR, f2, generally f2=150 Hz for ILS and 9 960 Hz for VOR, and th
REFERENCES:
patent: 3685053 (1972-08-01), Kirkpatrick
patent: 4414632 (1983-11-01), Murrell
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