An Interactive Computer Approach to Tolerance Analysis

An interactive technique for statistical tolerance analysis has been developed for a computer with graphic display. The computer program called TAP provides for random perturbation of parameter values, repeated evaluation of system performance, and display of distribution histograms. The interactive capability of the program enables the designer to introduce modifications to the system so that the relative effects of these changes can be quickly evaluated with the graphic display. The program has been implemented on a computer facility consisting of a CDC 3300 digital computer, an ITT digital display scope, and an EAI 8800 analog computer. Two applications are discussed to illustrate the adaptability of the technique to either linear or nonlinear problems. The digital simulation of an active circuit is used to show how the interaction with graphic display saves time in evaluating alternative designs. A hybrid simulation of an equalizer for a digital transmission system illustrates that complex time domain problems can be economically analyzed using TAP. In addition, it is shown how TAP is used to measure the reproducibility of an analog simulation.