How is mutual interference on 518 kHz among NAVTEX stations avoided?

The correct answer indicates that mutual interference among NAVTEX stations at 518 kHz is effectively managed through a combination of scheduled transmissions on a time-sharing basis, limiting power, and ensuring that station assignment codes are geographically separated.

Time-sharing is crucial because it allows different NAVTEX stations to operate at different times, thus preventing overlap and interference during their broadcasts. This scheduling ensures that when one station is transmitting, others are silent, minimizing the chance of any signal interfering with another.

Limiting transmitter power is also significant for avoiding interference. By ensuring that the signal strength isn't excessively powerful, the reach of each station is confined, reducing the risk of overlapping signals impacting areas where multiple NAVTEX stations might be in proximity.

Finally, the geographical separation of station assignment codes is essential. This means that the codes used by one NAVTEX station are not duplicated by another station within interference range, further reducing the risk of confusion or overlap in communications.

In contrast, options that involve sharing station assignment codes or operating all stations simultaneously, even with limited daytime operations or varying power outputs, would likely lead to greater interference rather than effectively preventing it. Thus, the practices in place establish a structured approach to ensure clarity and reliability in maritime communication.