Spectrogram is there.
P.51 of the manual states (When on RTA screen)
Spectrogram Mode
Press the Fn key to access the Spectrogram or to return to the RTA.
The Spectrogram presents a visual representation of the spectrum of frequencies in the signal as they vary with time. The amount of energy is displayed using colour from dark blue low level to red peak level. The screen presents an 8 second window to give you a history of the changes over time.