| 摘要 |
Apparatus and method for use in instrument landing system (ILS) localizer and/or glide-slope receivers for deriving course deviation information are described. Specifically, a detected incoming ILS (localizer or glide-slope) signal is first filtered in order to extract appropriate 90 and 150 Hz navigation tones therefrom. Thereafter, two streams of timing pulses are generated; the first stream is phase-locked to the 90 Hz navigation tone and the second stream is phase-locked to the 150 Hz navigation tone. The peak amplitude of the 90 Hz navigation tone is sampled in response to the occurrence of a particular timing pulse occurring in the first pulse stream and the peak amplitude of the 150 Hz navigation tone is sampled in response to the occurrence of a particular timing pulse occurring in the second pulse stream. The sampled values of both navigation tones are then combined to obtain the difference therebetween which, in turn, is used to produce a signal which represents the actual localizer or glide-slope course deviation.
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