Instrument Function > Modulation > ILS-GS Modulation
ILS-GS Modulation

ILS-GS modulation (Instrument Landing System - Glide Slope) is available for the basic unit (R&S SMA + frequency option R&S SMA-B10x) equipped with option R&S SMA-K25.

ILS systems provide information relating to the position of the air plane relative to the runway during landing. The ILS-GS system indicates if the air plane is above, below or on the glide path. The carrier is modulated by a 90 Hz and a 150 Hz tone and sent to a separate directional antenna system. The antenna array is arranged so that the 90 Hz signal is stronger above of the glide path, and the 150 Hz signal is stronger below the glide path. The information on position is provided after demodulation of the signals by evaluating the difference in depth of modulation (DDM).

Three different modes are offered for the ILS-GS test signal:
  • Norm
    Standard localizer/glideslope signal
  • 90 Hz
    Suppression of the 150 Hz modulation tone
  • 150 Hz
    Suppression of the 90 Hz modulation tone

An external signal can be added to the internal signal (EXT AM = EXT (MOD AM)). The external signal is input via the AM EXT connector.

The ILS-GS signal is output at the LF OUT connector at the front of the instrument.

 


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