What characteristic of Link 16 ensures communication remains secure against jamming?

The characteristic of Link 16 that ensures communication remains secure against jamming is frequency hopping. This technique allows the system to rapidly switch between different frequency channels during transmission, making it much more difficult for jammers to effectively target and disrupt the communication link.

By frequently changing frequencies, Link 16 communications enhance resilience against electronic warfare tactics. If a jammer targets a specific frequency, it may only disrupt communication temporarily, as the transmission will quickly hop to another channel. This method increases the robustness and reliability of communications, an essential feature for military operations where situational awareness and command and control are critical.

The other characteristics listed do not provide the same level of protection against jamming. For instance, signal strength is important for maintaining a good connection but does not mitigate the risk of interference from jamming. Static channel allocation would make a communication system more predictable and vulnerable to interception and jamming, while a constant data rate does not inherently add security against attempts to disrupt signals. Therefore, frequency hopping is the key feature that enhances security in the face of potential jamming attacks.