The radar display has the important purpose of visually presenting the output of radar receiver in a form such that an operator could accurately detect the presence of a target and extract information about its location. When the display is connected directly to the output of the radar receiver without further processed the ouput is called ‘raw video’. When the receiver output is processed by a detector it is called synthetic video or processed video.
Types of Displays:
A Scope:
A deflection modulated rectangular display in which vertical deflection is proportional to amplitude of receiver output and horizontal deflection is proportional to range.
D Scope:
An intensity modulated rectangular display with azimuth angle indicated in the horizontal direction and the range indicated in the vertical direction. It is used in military radar.
C Scope:
A two angle intensity modulated rectangular display with azimuth angle in the horizontal direction and the elevation angle in the vertical direction.
E Scope Display:
An intensity modulated rectangular display with range indicated in the horizontal coordinate and elevation angle in the vertical coordinate.
Plan Position Indicator (PPI):
An intensity modulated circular display in which echo signals from the reflecting objects are exposed with range and azimuth angle shown in polar coordinates.
Range Height Indicator (RHI):
An intensity modulated rectangular display with height of the target or altitude of the target along vertical axis and range along horizontal axis.
The cathode ray tube displays were used in early stages of the radar, the deflection modulated CRT, such as A Scope display in which a target is indicated by deflection of the electron beam was commonly used. The other type of CRT called intensity modulated CRT in which an echo is indicated by intensifying the electron beam and presenting a display on the CRT was also in use.