Traditionally, the SNR of spectra measured by step-scan FT-IR has been poor. We have accepted the penalty because step-scan allowed access to time-resolved spectroscopy on a wide range of time scales. Further, the alternative rapid-scan techniques such as stroboscopic and asynchronous sampling are susceptible to the same noise sources as step-scan. The bottom line is that the SNR of rapid-scan instruments is 1 to 100 times better for the same data collection time.