Explanation: A spectrum analyzer displays the amplitude of signals across a range of frequencies. This makes it the ideal tool for detecting and measuring *spurious signals* – unintended emissions like harmonics, parasitic oscillations, or broadband noise that fall outside an amateur station's authorized bandwidth. FCC regulations (Part 97) have strict limits on these unwanted emissions, and a spectrum analyzer allows an operator to ensure compliance and troubleshoot sources of interference. While a spectrum analyzer *can* show the bandwidth of an FM signal (related to deviation), or display carrier presence, or hint at AM sidebands, other instruments are generally more accurate or practical for those specific measurements. For example, an oscilloscope is better for AM percentage, and a frequency counter is simpler for carrier frequency. The spectrum analyzer's distinct advantage lies in its ability to visualize the *entire spectral output*, making it indispensable for identifying and mitigating unwanted signals.