Identification Friend Or Foe
In telecommunications, identification, friend or foe (IFF) is an identification system designed for command and control. It enables military and national (civilian-located ATC) interrogation systems to identify aircraft, vehicles or forces as friendly and to determine their bearing and range from the interrogator.
IFF was first developed during World War II. The term is something of a misnomer, as IFF can positively identify friendly targets but not hostile ones. If an IFF interrogation receives no reply or an invalid reply, the object cannot be identified as friendly but is not positively identified as a foe.
There are many reasons for friendly aircraft not to reply to IFF, such as battle damage or equipment failure, loss of encryption keys, and wrong encryption keys. Terrain-hugging aircraft are very often poor candidates for microwave line-of-sight systems such as the IFF system. Microwaves cannot penetrate terrain, and very often atmospheric effects (referred to as anomalous propagation) cause timing, range, and azimuth issues.
Read more about Identification Friend Or Foe: Historical, Method of Operation, Modes
Famous quotes containing the words friend and/or foe:
“... possibly there is no needful occupation which is wholly unbeautiful. The beauty of work depends upon the way we meet it—whether we arm ourselves each morning to attack it as an enemy that must be vanquished before night comes, or whether we open our eyes with the sunrise to welcome it as an approaching friend who will keep us delightful company all day, and who will make us feel, at evening, that the day was well worth its fatigues.”
—Lucy Larcom (1824–1893)
“In the morning glad I see
My foe outstretch’d beneath the tree.”
—William Blake (1757–1827)