As previously mentioned, a key advantage of the technique is that it increases the speed of data collection because a single square wave can provide amplitude information for a series of higher harmonics. Therefore, a single square input experiment produces several data points on the plot of amplitude ratio vs. frequency, whereas with a sinusoidal perturbation, each frequency experiment produces only one data point. Consistent with the observations of Shen and Rees, The number of usable harmonics in the FT-CSFR method is influenced by the quality of the square waves produced by the mass flow controllers and the detector's sampling rate.