This work began in 1994 with a contract to survey the extent and effect of velocity errors in the US Army XM-21 passive remote FT-IR detection system. It was proposed in that survey that digital signal processing was the key to better FT-IR spectrometers. In particular, the use of synchronized sampling of the laser and infrared channels was proposed. A method of processing these data that would eliminate the effects of velocity errors was also proposed, but it was computationally intensive. As usual, Manning Applied Technology moved with the deadly speed of a wounded sloth. In the years 1993 to 1995, step-scan systems which used extensive digital signal processing were built. These systems had a subtle flaw in that critical timing was shared between a personal computer (PC) and a digital signal processor (DSP). The flaw only affected very sensitive measurements such as polymer stretching. In studying these step-scan systems it was realized that all of the timing functions in a signal processing system should be tied to one clock. It had been realized much earlier that that instrument complexity, control and signal processing alike, can be shifted from electronic hardware to software.#