In modern combat conditions, it is important not only to detect a target but also to correctly determine its affiliation. Identification errors can lead to the engagement of one’s own forces, which in military practice is called friendly fire. That is precisely why special identification systems are applied in military equipment, which make it possible to quickly determine whether an object belongs to one’s own units.
One such technology is the «friend-or-foe» system. In international military practice, it is known as IFF (Identification Friend or Foe). Such systems are used in military aviation, air defense, unmanned platforms, and other types of equipment where it is important to quickly identify objects in the air or on the ground.
The «Friend-or-Foe» System: Purpose and Operating Principle
The «friend-or-foe» system is intended for the automatic identification of objects on the battlefield. Its main task is to determine whether a target belongs to one’s own forces or to the enemy.
The operating principle is based on the exchange of radio signals between the detection system and the equipment on board the platform. A radar or another system sends an interrogation signal, after which a transponder on board an aircraft, drone, or another object transmits a response signal.
If the response contains the correct identification code, the system identifies the object as «friend». In the case of no response or the receipt of an incorrect signal, the target can be marked as unknown or potentially hostile.
In modern systems, the identification process occurs automatically and is integrated into general systems for managing combat operations.
How the «Friend-or-Foe» System Works in Military Communication Systems
In most cases, the «friend-or-foe» system is integrated into radar complexes and military communication systems. When a radar or another system detects an object, it automatically transmits an interrogation signal in a defined radio-frequency band.
A transponder on board the equipment receives this signal and forms a response signal with encoded data. After this, the identification system analyzes the received signal and determines the affiliation of the object.
Such technologies are widely used in modern military communication networks and control systems, where it is important to ensure the rapid exchange of information between different units.
Interrogation and Response Signals in the «Friend-or-Foe» System
Identification systems use two main types of signals — the interrogation signal and the response signal. The interrogation signal is formed by the radar system or another detection asset. After receiving this signal, the transponder forms a response signal with encoded information.
Response codes can change depending on the operating mode of the system. In modern military systems, complex encryption algorithms are applied, which makes it possible to protect signals from interception or spoofing.
Thanks to such a principle of signal exchange, the system can quickly determine the affiliation of an object even in a difficult combat situation.
Using the «Friend-or-Foe» System in Air Defense, Aviation, and Ground Equipment
The «friend-or-foe» system is most widely used in air defense systems and military aviation. In such systems, identification makes it possible to determine the affiliation of aerial targets and prevent the engagement of one’s own aircraft or drones.
In military aviation, transponders are installed on board aircraft and transmit response signals to radar interrogations. Such systems can also be used in unmanned platforms and some types of ground equipment.
The issue of correctly identifying objects is also connected with the operation of electronic warfare assets. In some cases, the active use of EW can affect the operation of communication or identification systems. More about this can be read in the article: «Electronic friendly fire: how to avoid the negative impact of EW on one’s own military units», which examines situations where electronic systems can affect the operation of one’s own equipment.
Limitations of the «Friend-or-Foe» System in Combat Conditions
Despite its effectiveness, the «friend-or-foe» system has certain limitations. One of the factors is the dependence on the stability of communication channels and the serviceability of transponders.
In a difficult electromagnetic environment, radio signals can experience interference or losses. This is especially relevant in zones of active operation of electronic warfare assets.
The correct configuration of the system is also an important factor. Errors in the configuration or the use of outdated identification codes can lead to the incorrect determination of an object.
Protecting the «Friend-or-Foe» System From Signal Spoofing
One of the main tasks of modern identification systems is protection from signal spoofing. For this, cryptographic algorithms and the regular changing of identification codes are used.
Such mechanisms complicate the possibility of interception or imitation of signals by the enemy. In modern systems, additional signal verification mechanisms and a multi-level authorization system can also be used.
The stability of signal transmission in such systems largely depends on the characteristics of the radio equipment and antennas.
One example of antennas used in the radio systems of drones and other military platforms is the quadrifilar NR17 antenna. It is a type of antenna with a circular radiation pattern, which ensures uniform signal reception from different directions. Such antennas are used in the communication systems of unmanned platforms, receiving radio modules, and other radio-frequency complexes.
The antenna can be applied as a separate element of a radio system or as part of a larger equipment complex, where it is important to ensure stable signal reception regardless of the position of the equipment in space. Thanks to their design, quadrifilar antennas are well suited for systems where an object can change orientation during movement or flight.
Conclusions
The «friend-or-foe» system is an important element of modern military infrastructure, which makes it possible to quickly identify objects on the battlefield and reduce the risk of engaging one’s own units.
The operating principle of such a system is based on the exchange of interrogation and response signals between detection systems and transponders on equipment. This makes it possible to automatically determine the affiliation of objects and integrate identification into systems for managing combat operations.
The effectiveness of such systems depends on the stability of communication channels, the protection of signals, and correct integration into military equipment.
