| 摘要 |
<p>A digital circuit and system are described for detecting and smoothing step-functions or discontinuities in the signal representing height information in a photomapping system. The circuit is called a slope limiter. A threshold detection circuit provides a signal when the discontinuity exceeds predetermined values. Signal dividing circuitry then operates to divide the discontinuity signal (which is represented digitally) by a selected factor N. The divided value is then added and subtracted, respectively, to and from the trailing and leading signal values which are on opposite sides of the discontinuity. The result is that the original step-function signal is changed to a staircase signal of multiple steps. The disclosure includes a plurality of slope limiters in tandem so that the steps of a preceding limiter are acted on by a subsequent limiter. Repeated circulation of the digital signals in a circulating system permits repeated division of the steps in a manner which provides a desired degree of slope limiting. The height signal is thus smoothed through the time domain where the discontinuity existed.</p> |
