Which type of intrusion detection device is least likely to produce false alarms?

The least likely type of intrusion detection device to produce false alarms is a passive sensor. Passive sensors operate by monitoring and analyzing data from the environment without actively interacting with it. They typically rely on established patterns of normal behavior and are thus more adept at discerning between legitimate activity and potential intrusions.

Since passive sensors do not generate alerts based on their own active observations and are often designed to recognize specific behaviors or signatures, they tend to have a lower rate of false positives. This approach allows them to focus on interpreting genuine suspicious activity rather than reacting to every change in the environment, which can be a common issue with active sensors that may initiate alarms based on minor disturbances.

In contrast, devices such as active sensors, which actively probe for intrusions, can more easily generate false alarms due to their sensitivity to even the slightest changes in the monitored environment. Hybrid sensors combine the functionality of both types, which can also lead to more complexities and a higher chance of false alarms. Signal-based sensors may also be prone to false positives, especially in noisy environments where distinguishing between legitimate signals and noise can be challenging.

Thus, the operational design of passive sensors allows for a more precise and less intrusive detection method, leading to a reduction in false alarm rates.