Display enhancement technique for video moving trace display

Abstract

A system providing a substantially gapless continuous line display of an analog signal as a function of time on a television monitor. The input is digitized and each level of quantization corresponds to one of the raster display lines to give proper vertical deflection. During each line of raster scan an oscillator and counter sequence the input address to a memory through a desired number of horizontal sampling positions, requiring an address of the order of 8 bits. Each address gives an output of several bits giving in digital form the instantaneous y coordinate of the signal. This is digitally compared with the digitized associated raster line number in a first digital comparator. This is also stored in a register strobed from the above-mentioned counter just before each change of address. The raster line number and the stored previous output are digitally compared in a second digital comparator. If the line number is less than the current trace deflection but greater than the previous deflection, a first AND gate provides an output signal at that instant. Similarly, if the line number is greater than the current trace deflection but less than the previous deflection, a second AND gate provides an output signal. If the current deflection is equal to the line count, this also provides a signal. An OR gate receives these signals, and any one of them will provide a trace-brightening signal at the output of the OR gate. The 'equal output' signal is delayed by a time corresponding to 1/2 the horizontal sampling interval to improve the horizontal resolution.