Reinforcement of RADAR target
Rapid target identification
Extension of secondary RADAR coverage area (up to 200 miles)
Transmission of altitude and other data
The components of the secondary surveillance RADAR are as follows:
Interrogator on the ground
Transponder in an aircraft
Display on an ATC RADAR scope
When the word RADAR is used, it refers to a primary RADAR system. Primary RADAR
differs from secondary surveillance RADAR in that primary RADAR displays reflected
signals and does not display signals that have been transmitted by an airborne
transponder. The two systems work together and are displayed on the scope at the
same time (see Figure 5-21).
Figure 5-21 -- Components of the secondary RADAR.