![]() ![]() This forms by superimposing the individual signals the required signal in space. A load distributor (Antenna Distribution Unit, ADU) divides the RF by amount and Phase to a sophisticated system on the individual antennas, each for CSB and SBO according to different laws. The basic ILS signals (COD and SBO) are fed into the up to 21 dipoles via a high-frequency load distributor that feeds the transmitting antenna. Where k is the relative level of the SBO signal relative to the CSB signal, and f is the relative phase of the SBO signal to the CSB signal, and Again, the mathematical formula:ĭ(t) = k cos(ωt + f i) (2) In this SBO signal, the 150Hz NF signal becomes out of phase and the 90Hz AF signal in-phase modulated relative to the COD signal. In addition, a signal with suppressed carrier (SBO, Side Bands Only) is generated. M90 and M150 are the modulation factors, those at which LLZ = 0.2 is to be set. Where ω caris the angular frequency of the carrier and ω fundthe angular frequency of theģ0 Hz fundamental frequency. Mathematically, it can be described as follows: This signal is called CSB (Carrier and Side Bands). The carrier oscillation in the localizer frequency range is 108.00 MHz to 111.975 MHz modulated with a 90Hz and a 150Hz tone signal. The modulation type of all ILS transmitters is the good old amplitude modulation (AM). The infographic below describes the system architecture of an Instrument Landing System.įig1. Instrument Landing System ILS ILS System Overview This article uses the following abbreviations: ![]() This article requires an advanced knowledge of mathematics. This article describes signals and operation of an Instrument Landing System ILS, Distance Measuring Equipment DME and a VHF Omnidirectional Range (VOR). ![]()
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