Which component is essential for ensuring signals can be viewed simultaneously in dual-trace oscilloscopes?

In dual-trace oscilloscopes, the ability to observe two signals on the same screen simultaneously relies on the use of dual probes. Dual probes allow the user to connect each channel of the oscilloscope to a different signal source. This setup is essential for comparing and analyzing the behavior of two distinct signals at once, such as observing different phases of waveforms or assessing the timing relationship between two signals.

Using a single probe would not enable simultaneous viewing of both signals, as it can only measure one signal at a time. While other components, like a mixing module or a signal generator, play roles in specific functions within an oscilloscope or in signal testing, they do not directly facilitate dual-channel signal observation. Thus, dual probes are key for the functionality required to leverage the full capability of dual-trace oscilloscopes effectively.