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The deployment of modern, high precision weapon systems and their effectiveness depend to a large degree on a timely and accurate identification of all targets ­ both friendly and hostile. This presentation introduces the basic concepts and operations of the Identification Friend or Foe (IFF) systems currently deployed in major US and NATO combatants. The directly related commercial aircraft identification equipment is the Air Traffic Control Radar Beacon System (ATCRBS) or the Secondary Surveillance Radar (SSR). These two systems share the same operating philosophy, waveforms, and frequencies.

1937, radio recognition identification friend-or-foe (IFF) system, the Model XAE, which met an urgent operational requirement to allow discrimination of friendly units from enemy units. 1958, the FAA had established the Air Traffic Control Radar Beacon System (ATCRBS), which is essentially the civilian version of the Mark X. The International Civil Air Organization later adopted the ATCRBS, making the Mark X the basis of the world's air traffic control system. 1960, It was the first IFF system to use cryptographic techniques to prevent deception where an enemy appears as a friend by using a captured transponder.

 Identification, Friend or Foe (IFF): is a cryptographic identification system designed for command and control, that enables military, and national interrogation systems to distinguish friendly aircrafts, vehicles or forces, and to determine their bearing and range from the interrogator.

Modern IFF systems are basically Question/Answer systems.  An interrogator system sends out a coded radio signal that asks any number of queries, including: Who are you?  The interrogator system is frequently associated with a primary radar installation, but it may also be installed aboard a ship or another airplane.  The interrogation code or challenge is received by an electronic system known as a transponder that is aboard the target aircraft.  If the transponder receives the proper electronic code from an interrogator, it automatically transmits the requested identification back to the interrogating radar.  The IFF system is also known as secondary radar Because it was developed and used as an adjunct to the primary echo-type detection radar.

 Each vehicle is provided with: o a radiation transmitter o a receiver with a detector to detect radiation transmitted by other vehicles.  Steps: 1.Each transmitter can transmit a first coded signal which can be detected by the receivers in other vehicles. 2.The receivers provide an unblocking signal after the first coded signal is correctly identified. 3.The unblocking signal clears a radiation transmission path in the vehicle. 4.This path containing a reflector which reflects the received signal back to the source of the transmission. 5.The reflector adds a further predetermined code to the signal reflected from the reflector with each vehicle having another detector for detecting a reflected signal and a device to identify the further predetermined code.