NAVTEX broadcasts typically achieve maximum transmitting range at what time?

NAVTEX broadcasts typically achieve maximum transmitting range at what time?

• A. Middle of the night
• B. Early afternoon
• C. Sunrise
• D. Mid-morning

Answer: (A)

The main factor is how low-frequency NAVTEX signals propagate. NAVTEX uses a very low frequency around 490–518 kHz, so its range depends on ionospheric conditions and atmospheric noise. During the day, the D-layer in the ionosphere absorbs MF signals and noise from human activity is higher, which shortens the practical range. At night, that absorption diminishes and the ionosphere can support longer skywave propagation, while overall noise is reduced, allowing the signal to be received farther away. So the maximum transmitting range typically occurs in the middle of the night.

The main factor is how low-frequency NAVTEX signals propagate. NAVTEX uses a very low frequency around 490–518 kHz, so its range depends on ionospheric conditions and atmospheric noise. During the day, the D-layer in the ionosphere absorbs MF signals and noise from human activity is higher, which shortens the practical range. At night, that absorption diminishes and the ionosphere can support longer skywave propagation, while overall noise is reduced, allowing the signal to be received farther away. So the maximum transmitting range typically occurs in the middle of the night.