When "almost" is good enough: a fresh look at DSP clock rates

Traditional DSP mixed-signal coherent test techniques require precise frequency ratios. This paper explores the limits of this requirement to define how closely rates must match ideal ratios to obtain proper results. Both worst-case and typical situations are considered. Worst-case conditions allow errors on the order of one part in 200,000,000,000. While small, this error tolerance allows changes in tester architecture that can simplify the design of DSP test programs.