Communications: directive radio wave systems and devices (e.g. – Directive – Beacon or receiver
Patent
1999-03-24
2000-08-01
Tarcza, Thomas H.
Communications: directive radio wave systems and devices (e.g.,
Directive
Beacon or receiver
342394, G01S 116, G01S 118, G01S 130
Patent
active
060973382
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a glide path transmitter device for the instrument landing system (ILS) with a plurality of antenna radiators by way of which low-frequency modulated high-frequency signals, containing various carrier and side-band components, are emitted, which are superimposed in the Fraunhofer region, where they form a guide signal that can be analysed by aircraft, the phases of the carrier oscillations of the high-frequency signals to be emitted, which form the guide signal, being in fixed relation to one another.
2. Discussion of the Invention
In known systems of this type, especially in a so-called ILS M-type array and B-type array, carrier signals (CSB) and side-band signals (SBO) are emitted by way of antennae A1, A2 and A3 or A1 and A2 in the B-type array arranged at different heights above the ground. The signals are superimposed on one another in the Fraunhofer region where they form guide signals corresponding to the ILS standard, which can be analysed by aircraft. As is well-known, each antenna does not receive just one single signal component, rather a plurality of superimposed signal components has to be fed to some antennae. This is done by generating the required high-frequency signal in a feed network, that is a so-called load distributor, by adding the pure carrier signals (CSB) and side-band signals (SBO) already boosted to the required output power. Phase adjustments, which are necessary for the most precise setting possible of the glide path of the ILS system, especially when setting up the system for the first time, require phase shifters, that must be manually adjusted, arranged in proximity to the antennae. The load distributor is costly and prone to faults.
SUMMARY OF THE INVENTION
The object of the invention is to identify a simpler transmitter device. This object is achieved according to the characterising part of claim 1, in that for each of the high-frequency signals fed to an antenna radiator a separate digitally controlled modulator is provided, which modulates the phase and amplitude of a high-frequency oscillation fed to it according to a pre-determined pattern and feeds the modulated high-frequency signal into the antenna radiator assigned thereto.
In the invention, therefore, the high frequency to be emitted is not generated by a load distributor, rather signals are generated in the modulation that can each be fed directly to a single antenna without a load distributor, that is without complicated and costly superimposition in proximity to the antenna. Only when generating the clearance signal, as is also usual in known systems, is this generally to be fed to two of the three antennae, for which purpose simple power couplers, especially 3dB couplers, can be used. Another advantage is that by influencing the modulators the phase of the signals fed to the antennae can be modified so that manually operated phase shifters can be dispensed with. Influencing the modulators is possible by purely electrical means, thereby also facilitating a remote control and automatic feedback control.
When surveying the glide path with the aid of an aircraft, the invention advantageously allows the necessary adjustment to be performed very rapidly as a function of the survey result and the system requirements, so that the time needed for the survey aircraft and hence the costs of the survey, and the time needed for setting up the system can be reduced, because the necessary adjustments can be performed more quickly due to the absence of manually adjusted phase shifters.
In one embodiment of the invention a modulation signal generator is proposed for generating the pattern fed to the respective modulator, and the modulation signal generator is designed in such a way that it generates the pattern on the basis of at least one wave form digitally stored in a memory. One advantage of this is that digital storage permits fast, accurate calculation of the pattern and facilitates modification.
In one embodiment of the invention it is p
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Kleiber Herbert
Rupprecht Rainer
Stammelbach Jurgen
Airsys Navigation System GmbH
Mull Fred H
Tarcza Thomas H.
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