zweifrequenz - sendevorrichtung with modulationsphasung exceeded 100 mg / l for a instrumentenlandeanlage

摘要

Two-Frequency Transmitting Apparatus with Tone-Modulation Phasing for an Instrument Landing System Two-frequency transmitting apparatus (S1, S2, LA) for instrument-landing systems is disclosed which is insensitive to so-called DDM distortions caused by reflections of the clearance signal from obstacles (H) located near the runway (RW). This insensitivity is achieved by different phase shifts of the equal modulation frequency (90 Hz and 150 Hz) used for the course and clearance signals. The different phase shifts correspond to a phase shift of a common fundamental frequency (30 Hz). The two-frequency transmitting apparatus can be used to specify a localizer course or a glide path. Fig. 1