Which of the following test instruments is used to display spurious signals and/or intermodulation distortion products generated by an SSB transmitter?
Why A spectrum analyzer displays amplitude versus frequency, so every signal a transmitter puts out shows up as a separate peak at its own frequency. Spurious emissions, harmonics, and the third- and fifth-order intermodulation products of a two-tone SSB test appear as sidebands beside the wanted signal, and their level can be read directly in dB below PEP. An oscilloscope, by contrast, works in the time domain and can only show gross envelope flat-topping, not which frequencies are present.
Watch out A network analyzer is the closest tempting choice, but it injects its own known signal to measure a device's gain, loss, phase, and impedance (S-parameters); it characterizes circuits, not the unwanted output of a transmitter. A logic analyzer looks at digital bit streams.
Spurs and IMD are a frequency-domain problem, so use the frequency-domain instrument: the spectrum analyzer.