How does an operator determine when the target moves off the axis in a single-lobe scanning system?

In a single-lobe scanning system, the determination of whether a target has moved off-axis is primarily indicated by a decrease in the strength of the reflected signals. When the target is within the designated detection axis, the echoes or reflections received are typically strong and consistent. As the target begins to move away from this axis, the angle of incidence changes, which causes the reflected signals to weaken due to the geometry of the reflection process and the overall gain of the system.

When the target moves off-axis, the less direct path of the reflected signal, combined with potential interference and scattering, typically leads to a noticeable drop in signal strength. This decrease signals that the target is no longer optimally positioned to return signals back to the system's sensor. Therefore, tracking changes in signal strength is a reliable method for operators to assess the position of a target in a scanning system, making it the correct answer in this context.

The other factors such as observing the target's speed, a change in target location, or an increase in signal noise may provide some insights or context but are not definitive indicators of off-axis movement in the same direct manner that signal strength is. These factors may also cause misleading interpretations without the clear correlation that signal strength provides in assessing position relative to