Final answer:
The localizer and glideslope systems use radio navigation signals to guide aircraft laterally and vertically during landing, with the localizer using VHF signals and the glideslope using UHF signals to indicate aircraft position relative to the runway.
Step-by-step explanation:
The basic operating principle of the localizer and glideslope systems lies in radio navigation technology used to guide aircraft during the approach and landing phase of flight. The localizer provides lateral guidance to the runway's centerline, while the glideslope offers vertical guidance to ensure the aircraft is on the correct descent path. Localizer signals are transmitted on a very high frequency (VHF) and consist of a pair of directional signals. One signal modulates at 90 Hz and the other at 150 Hz; the receiver on the aircraft interprets the difference in these modulations to determine the position relative to the runway's centerline. If the plane is to the left of center, the 90 Hz modulation is stronger; if it's to the right, the 150 Hz is stronger.
The glideslope, on the other hand, transmits two UHF signals at similar frequency modulations, but they are oriented in a vertical plane. As the aircraft approaches the optimal glide path, it will receive an equal amount of both frequencies; deviations above or below the glide path result in the dominance of one frequency over the other. This provides pilots with real-time feedback on altitude and descent rate needed to make a safe landing.