Instrument Function > Modulation > ILS-LOC Modulation
ILS-LOC Modulation

ILS-LOC modulation (Instrument Landing System - Localizer) 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-LOC system indicates if the air plane is to the left, right 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 on the left side of the glide path, and the 150 kHz signal is stronger on the right side of 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-LOC test signal:
  • Normal
    Standard localizer/glideslope signal + optional COM/ID tone (can be switched on)
  • 90 Hz
    Suppression of 150 Hz modulation tone
  • 150 Hz
    Suppression of 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 at the rear of the instrument.

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

 


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