A secondary radar system is a cooperative target
identification system in which the interrogator transmits an encoded signal
to a target. The signal transmitted by the secondary radar is intercepted and received by the target. The
target has a transponder on board that interprets the encoded
signal and transmits an encoded reply back to the interrogator.
The secondary radar system receives and interprets the
target's encoded signal.
The identification friend or foe (IFF) system is
a good example of a secondary radar system
that is in wide use in the military environment.
deal of valuable information can be provided to the secondary
radar by the target's transponder. The transponder provides
an identifying code to the secondary radar that
then uses the code and an associated database system to
look up aircraft origin and destination, flight number, aircraft type,
and even the numbers of personnel on board. This type
of information is clearly not available from a primary radar
Secondary radar systems are also known as secondary
surveillance radar (SSR).
Other topics in our resources on Radar related to Secondary Radar include: