A system and method are provided for making time domain measurements of a wideband periodic radio frequency (RF) signal using a narrowband measurement instrument operating in a frequency domain. The method includes receiving the periodic RF signal at a single port corresponding to a receiver of the measurement instrument; determining a complex absolute signal having amplitudes and phases of spectral components of the periodic RF signal over an entire bandwidth of the periodic RF signal in the frequency domain; and reconstructing a time domain signal corresponding to the periodic RF signal by transforming the complex absolute signal from the frequency domain to the time domain.