Real-time spectrum analyzer including frequency mask gate and method of operating the same

Abstract

A real-time spectrum analyzer for measuring time domain data sampled from an input signal includes a processing unit and a density histogram memory unit. The processing unit includes an FFT engine, a frequency mask detector and a frequency mask gate. The FFT engine performs FFTs on the sampled time domain data to provide FFT spectra, each FFT spectrum including multiple FFT points. The frequency mask detector determines whether each FFT point in each spectrum meets a trigger condition, and generates gate control signals corresponding to the FFT spectra based on the determinations. The frequency mask gate receives the FFT spectra and the gate control signals, and outputs only select FFT spectra that contain at least one FFT point that meets the trigger condition in response to the corresponding gate control signal. The density histogram memory unit stores the select FFT spectra for generating in a density histogram.