IFF (Identification Friend or Foe)

Also Identification Friend or Foe, abbreviated as IFF. It is an electronic system used for identifying military or civilian objects. However, it doesn't necessarily have to be flying objects only.

This electronic system operates on the basis of radio signals, thanks to which it is possible to determine which objects on the battlefield are allied and which belong to the enemy. The device consists of two parts: an interrogator, which can either be onboard the object or a network of ground radar antennas. The second part of the device is a transponder, which has the logical task of responding to the signal to determine which side the object belongs to.

The IFF system was developed during World War II, where battlefields were often very chaotic, and it was necessary to recognize to which side an object belonged. An interesting fact is that the name of the device is not entirely accurate. The radar is only capable of identifying friendly objects that are equipped with the same or compatible system. However, if the interrogator receives an incorrect or no response, the object is not marked as friendly, and it is not precisely identified as hostile either.

Positive identification occurs when the interrogator of one object (e.g., an aircraft) sends an encoded signal, which prompts the transponder of the target object to respond. The encoded signal must match according to a specific cryptographic key; in that case, the target object is marked as friendly. Since World War II, the development of these devices has, of course, advanced to a completely different level and can determine with much greater accuracy to which side an object belongs. Currently used systems in Western countries include, for example, Mark (Mk) XII, AN/APX-111, and AN/APX-113.