What does a spectrogram represent in vibration analysis?

A spectrogram is a powerful tool used in vibration analysis that visually represents the frequency content of a signal over time. It displays how the different frequencies in a vibration signal vary, allowing analysts to identify specific frequency components that may indicate mechanical issues such as imbalance, misalignment, or resonance.

In a spectrogram, the horizontal axis typically represents time, while the vertical axis shows frequency. The intensity or color of each point in the spectrogram indicates the amplitude of the signal at that particular frequency and time. This ability to visualize the frequency response enables engineers to analyze the behavior of machinery under different operational conditions and over time.

Option B is correct because it highlights the crucial function of the spectrogram in providing insights into how the vibration characteristics of a system evolve. By understanding the frequency content, analysts can diagnose problems accurately and monitor changes in mechanical performance, making this tool essential in predictive maintenance strategies.