An indicator on which signals caused by targets appear as vertical deflections on a horizontal range trace. By means of a calibrated scale the approximate range of any target can be read instantly. Approximate azimuth and/or elevation data may be obtained by observing the direction of the antenna when a signal is at maximum intensity. Much more accurate azimuth and elevation data can be obtained by means of pip matching on a modified form of "A" scope. (See PIP MATCHING). It is possible also to get an estimate of the size of targets from an "A" scope. This type scope is often used for tuning up sets and is the basic display in many. The vertical defection shown above at the start of the trace is caused by the transmission of the radar pulses.