Patent US 4,092,567

A diamond marker generator circuit generates a diamond-shaped marker making a spot or point on a curve of an input signal being measured. Despite changes in the display or sweep rate of the input signal, the marker's size is kept constant, and its intensity or contrast is maintained at a constant level relative to the intensity of the curve. One marker is generated above the curve to mark a current point of interest to a user. One or more markers are generated below the curve to mark previous points of interest.