Radar Warning Receiver is an instrument used to detect the presence of any airborne or ground based radar. This system can be mounted on variety of platforms i.e Aircraft, Naval Ships, Ground Systems etc. The warning can then be used manually or automatically, to evade the detected threat. Depending on the RWR system, it can be as simple as detecting the presence specific radar band. For more critical situations, RWR systems are often capable of classifying the source of the radar by the signal’s strength, phase, and waveform type, such as pulsed power wave or continuous wave with amplitude modulation or frequency modulation. The information about the signal’s strength and waveform can then be used to estimate the most probable type of threat the detected.
Radio waves originated by radars have a wide range of frequency bands. The frequency used by airborne and ground based platforms may be different to detect a similar target. More-ever there are other parameters i.e Pulsed Signals, Continuous Waveform, Amplitude which are task and system specific. An aircraft was several antennas onboard that are used to detect the presence of radar waves in the surroundings. These antennas scan periodically full range of frequency bandwidths to detect the specific frequency present around the system. The resonance of the source frequency with the one in the antenna of RWR creates audio signals, which are different with respect the to amplitude, direction of origin, waveform shape etc. These signals provide the pilot situational awareness and helps him to deviate the threats.
The noise tones are fed into the headphones of aircraft pilot, if changes to continuous beep, means his aircraft has been locked and is being tracked by a radar which may fire a missile to down the hostile. RWR integrated with onboard systems can provide estimated distance of radar battery or airborne system along with the location on MFDs in the cockpit. Autonomous missile and radar jamming techniques may be applied to safeguard own-self. RWR on modern platforms provides 360* of coverage.
Apart from general purpose RWR integrated within the aerial systems, there are also special purpose RWR pods available for SEAD operations in which there are plenty of tracking and fire-control radars along with SAMs. In such scenarios, detection of multiple frequencies and jamming them is a necessity to avoid tracking which can result in the form of firing of SAM and costing life of pilot as well as machine. i.e The AN/ASQ-213 HARM targeting system is a targeting pod mounted to the side of an F-16 aircraft that enables the aircraft to track the location of hostile radar systems that can then be engaged with AGM-88 HARM or other air-to-surface weapons. These special purpose RWR pods help in firing of Anti-Radiation Missiles. More-ever they also help the pilot to do excessive maneuvers and specifically jam the fire control radar of an air defense system if a SAM has been fired.
Examples of RWR systems in service of PAF
BM/KJ-8602 RWR is being co-produced in collaboration with M/s CEIEC China and is designed to provide the pilot with real time and unambiguous threat warning over 360 degrees thus reducing vulnerability of the combat aircraft to radar associated weapons. Currently two different models of RWR are available i.e. BM/KJ-8602 RWR and BM/KJ-8602A RWR. PAC also provides the life cycle maintenance of these two RWR models to PAF.
Appended below are salient features of the system
- Multi-signal Capability.
- Integration with Chaff/Flare Dispensers.
- High MTBF.
- User Programmable Threat Library.
- Built in Self-Test.
F-16 Fighting Falcon
The Loral AN/ALR-56A RWR is designed to detect incoming radar signals, identify, and characterize these signals to a specific threat, and alert the aircrew through the TEWS display. The AN/ALR-56 system features four external antennae mounted on each fin tip and on both wingtips, with a fifth blade-shaped antenna underneath the forward fuselage. The solid state ALR-56 is based on a digitally controlled dual channel receiver that scans from 6-20 GHz, while changes in the threat can be accommodated by software modifications.