Technique for plotting a variable-width signal in a fixed-width plot area

Abstract

A data acquisition device permits plotting of cylinder firing cycles, of varying-frequency, on a fixed-plot area of a CRT screen. Each cylinder firing cycle is sampled, at a constant sample rate, and consecutive sets of sample points, each containing a fixed number of sample points, is generated. On the basis of a unique data reduction technique triggered after the collection of each consecutive sample-point set, certain of the sample points considered superfluous are deleted from the set and the remaining appended to a temporary buffer. The sample-points in the temporary buffer further undergo reduction of the sample points when certain conditions occur, such as buffer full, at which time certain ones are discarded and others are kept. At the end of a cylinder firing cycle, the remaining points are further reduced and a final-set is generated, representative of a full cylinder firing waveform, consisting of sample points equal in number to the plot-width of the CRT screen.