What must happen to a video signal to observe the composite triple beat (CBT) on a spectrum analyzer?

To accurately observe the composite triple beat (CBT) on a spectrum analyzer, a video signal must be synchronized. Synchronization is essential because it allows the spectrum analyzer to correctly interpret the timing and pattern of the signal being analyzed. When the signal is synchronized, it aligns the various components of the video signal, ensuring that the frequency and phase relationships can be accurately displayed, which is vital for identifying phenomena such as the CBT.

In contrast, simply turning off the signal would not produce any meaningful output on the spectrum analyzer, as there would be no signal to analyze. Amplifying or adjusting the signal might enhance or modify its characteristics, but without the critical step of synchronization, it would not produce or allow for the observation of the CBT phenomenon.