Which signal is considered the weakest that produces a visible output in a receiver?

The Minimum Detectable Signal is considered the weakest signal that can produce a visible output in a receiver because it represents the threshold level at which the signal can be reliably detected above the background noise. This metric helps engineers and technicians determine the sensitivity and effectiveness of a receiver.

When a signal is at or above this threshold, the receiver can process it and provide a recognizable output, allowing for proper communication or data transmission. If the signal were any weaker, the noise would mask it, making detection impossible. Understanding this concept is crucial in fields such as radar and communication systems, where reliability and clarity of the signal are paramount.

In contrast, other options like Signal-to-Noise Ratio reflect the quality of the signal relative to the level of background noise, the Maximum Desired Signal could refer to the strongest signal level that a receiver can handle before distortion occurs, and Medium Density Signal may not directly pertain to detection clarity or visibility and lacks a standard definition in this context.