Method and apparatus for calibrating a scan convertor

Abstract

An oscilloscope includes a digitizing camera mounted thereon for recording waveforms on the oscilloscope screen. The digitized signals representing the waveforms are stored in the computer. In the calibration process a plurality of baselines substantially equidistant from one another are scanned on the screen and thereafter a plurality of sine waves are scanned. The phase differences between each sine wave and an associated ideal sine wave are determined and are used to create a map which associates each point on a waveform of interest appearing on the oscillosope screen with a time value that corrects for nonlinearities in the horizontal axis which are injected by the optics, nonlinear voltages, etc. Another map is created utilizing the baseline scan which corrects for such nonlinearities in the vertical axis. A data waveform of interest appearing on the scope is mapped from its physical location on the target, using the time and voltage maps, onto a record which is corrected for nonlinearities and gain errors.