Challenges and Countermeasures of the hottest airb

Challenges and Countermeasures of airborne target detection and positioning technology

in the field of military aviation, it is an effective way to improve the combat effectiveness of aircraft by strengthening avionics system. The importance of many detection methods led by radar makes it one of the most attractive technologies in the field of avionics. For a considerable period of time in the future, radar technology, infrared and photoelectric detection technology will still play an important role in combat aircraft

airborne

radar, which has a history of more than 60 years, is still difficult to achieve by other detection means such as infrared and laser, regardless of its long-distance detection ability or all-weather characteristics. Infrared, laser and other detection means have their special advantages in the concealment, accuracy and resolution of detection, as well as the ability to work and survive in the harsh electronic warfare environment. It can be predicted that the airborne target detection and positioning in the 21st century will develop in the direction of comprehensive application of various detection means, mainly radar detection means, supplemented by infrared and laser detection means

challenges

the stealth technology of military aircraft makes detection more difficult

military aircraft with good stealth characteristics, such as F-117 and B-2, have been in service in the 1980s and 1990s. And they have been put into use in NATO's air strikes against the Federal Republic of Yugoslavia. The F-22 and JSF with stealth capability will also be incorporated into combat forces at the beginning and middle of this century. At the same time, Russia and Europe are also actively developing stealth aircraft. Not only the stealth improvement of active fighters is under way, but also the stealth ship and stealth vehicle technology are being developed

● delay the discovery time of the other party's radar, so that its air defense system has no time to make an effective response

● reduce the coverage area of the other party's radar, and increase the gap in the air defense area

● force the radar of the other party to increase the transmission power, so as to enhance the detection advantage of electronic reconnaissance (ESM) system

● reduce the interference power required by stealth aircraft to cover itself

● strengthen the effect of bait jamming tactics

2. High performance silicone and monomers: the progress of silicone high temperature resistance and high insulation electronic warfare technology poses a great threat to the detection means

the continuous progress of radar and photoelectric technology will inevitably promote its opposite - electronic warfare technology to be more perfect and effective. The integrated electronic warfare system (iNews) developed by the United States for the F-22 integrates many previous discrete systems and equipment into a highly integrated system with multiple functions such as radar threat warning, missile attack warning, electronic reconnaissance, jamming release, etc. INews fully adopts modular structure and software control, which is easy to refit on other combat aircraft. Compared with the advanced self defense Jammer (ASPJ) currently in service, iNews has many improvements. First, its coverage frequency is far beyond the range of 2 to 18 gigahertz, extending to millimeter wave, infrared and visible light; Secondly, it will integrate with avionics system to a greater extent to realize data exchange and resource sharing. On the F-22 aircraft, the data processing part of iNews has been integrated into the general integrated processor (CIP) of the aircraft. In the design scheme of JSF, the degree of integration has been further improved

we should find a new way to identify targets effectively, accurately and in real time as soon as possible.

the combat environment of modern battlefield is very complex, with many countries participating in the war, many types of weapons participating in the war, and the battle front is intertwined. Therefore, there are often cases of accidental injury to our own side or the middle party. It can not only find the target, but also further identify the target. At present, this problem has not been well solved

the development of weapon system puts forward higher requirements for detection system

the multi-target attack and rapid mobility of the new generation of weapons require that the corresponding detection system can find, identify and track multiple targets at the same time, and make a rapid response to the changes of battlefield situation, so as to ensure that the weapon system is provided with all the required carrier and target parameters. For example, the range of advanced medium range air-to-air missiles (such as aim-120 of the United States, Micah of France, R-77 of Russia) with the ability to ignore after launch is more than 60 kilometers. Therefore, the radar is required to ensure that its service life of the target to be attacked is at least 100 kilometers under the condition of scanning while tracking (TWS). Targets such as stealth aircraft and cruise missiles with hundreds of times reduced radar cross-sectional area (RCS) and the unpredictable electronic warfare environment undoubtedly pose great challenges to detection methods

in the future, with the countermeasures that Volvo rear plate spring project is promoting as planned

pulse Doppler radar is more mature

after nearly 30 years of development, pulse Doppler (PD) radar technology has been very mature. The country that has mastered the production capacity of PD radar has developed from the United States in the 1960s to France, Britain, Russia, Sweden, Italy, Israel and other countries. PD radar system with down looking target capability has become the basic system of modern airborne fire control radar and airborne early warning radar. In recent years, this radar system is more compatible with other radar systems, such as the combination with synthetic aperture radar system to form a new generation of airborne fire control radar. It not only has good air-to-air combat capability, but also has high-resolution mapping capability, providing target positioning capability for precision strike

active phased array technology is becoming practical.

the new system is the driving force to improve the detection ability of radar. Phased array technology is a new radar technology that is developing in recent years. Compared with single pulse, pulse compression, synthetic aperture and pulse Doppler, it has a deeper and broader impact on radar performance. The development of phased array technology is based on the comprehensive achievements of antenna array technology, microwave technology, signal and data processing technology, microelectronics technology and other disciplines. In the 1980s, the phased array system with passive feeders has been preliminarily applied. The F-22 active phased array fire control radar is a more advanced phased array radar. From the beginning of this century, active phased array technology will be widely used in the field of airborne radar. This radar has the following characteristics:

● fast scanning speed: the mechanical scanning speed of the antenna is generally difficult to exceed 100 degrees/second. It usually takes several seconds to more than ten seconds to cover a space with an azimuth of 120 degrees and a pitch of 10 degrees. For phased array radar, the scanning speed is only limited by the number of target echoes, and its scanning speed can be in milliseconds, or even microseconds

● simultaneous and multifunctional: that is, the active phased array can complete more than one radar function at the same time. It can use a part of the aperture (array element) to complete one function, and use another array element to complete other functions. You can also use the method of time division to alternately use the same face to complete multiple functions

● low probability of being intercepted: in the current extremely severe electronic interference environment, it is very necessary for any electronic equipment to contact the enemy secretly and silently. The amplitude and phase of the aperture field of the active phased array radar can be controlled at will, which can make the zero value of the antenna sidelobe point to the enemy jamming source, so that it cannot receive the radar signal of effective strength, so it cannot implement effective jamming. In addition, the active phased array is easy to manage the transmission power and increase the electromagnetic concealment

● the radar itself has a small cross-sectional area: when designing stealth aircraft, all features that may be found by enemy detectors, such as heat, sound, light, electromagnetic and other factors, should be limited. The electromagnetic reflection characteristics of radar are the key restricted objects. Therefore, all factors that can cause radar electromagnetic reflection on the aircraft should be eliminated or limited one by one. Research and experiments show that the radar antenna and rotating support of the nose are reflectors with large RCS, and the stealth effect will be greatly weakened. By using active phased array and specially designed radome, this unwanted reflection will be minimized

● good reliability: since the signal transmission and reception are composed of hundreds of independent receiving/transmitting and radiation units, a few unit failures have little impact on the system performance. The test shows that 10% of the units fail, which has no significant impact on the system performance and does not need immediate maintenance; When 30% failure occurs, the system gain decreases by about 3 dB, and the basic working performance can still be maintained. This "perfect degradation" feature is very necessary for combat aircraft. Secondly, due to the elimination of centralized high-power transmitter and antenna mechanical servo system, various reliability problems caused by high-power and motion system no longer exist

synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR) technology are widely used in space/surface high-resolution detection and recognition.

SAR can provide ground mapping images under all-weather conditions with high resolution. At present, it has begun to equip reconnaissance aircraft, bombers and fighter planes. SAR can work day and night, and can penetrate dust, smoke, mist and battlefield camouflage. This ability is not possessed by electro-optical and infrared sensors. SAR has a longer distance working ability than electro-optic sensor. Ground reconnaissance and mapping can be carried out outside the enemy defense area. Traditionally, ISAR is mainly used to identify naval ships. In recent years, ISAR technology is being developed for the detection and identification of military targets such as ground vehicles, missile launchers and combat weapons

detection technology of low observability targets

stealth and anti stealth are the unity of opposites. The emergence of stealth aircraft has brought challenges to the detection system. The radar is required to improve the sensitivity of detecting low observability targets. According to the original experimental method of radar work, if the RCS of the target is reduced by an order of magnitude, the performance of the radar must be improved by 4 orders of magnitude to maintain the original detection range of the radar. Facing such challenges, the development of detection technology for low observability targets has become a hot topic. Adopt lower frequency band again and develop higher millimeter wave frequency band; Adopt data fusion technology of multi band detection system; The use of multistatic and radar group detection technology are some of the current efforts. However, due to some technical reasons, such as the required physical size is too large, the weight is too heavy, and the cost is too high, the above technology is still difficult to be fully used in airborne conditions in a short period of time

survival and working ability in electronic warfare environment

any electronic equipment in modern war should be able to work in the harsh electronic interference environment. The jamming system controlled by computer can quickly measure the intercepted radar signal parameters, and adaptively control the frequency, transmission power and signal waveform of the jamming system. In the face of this threat, the radar must make a rapid response, and the computer selects the best countermeasure scheme. Improving the anti-jamming ability of radar through the improvement of software is a widely used technical means at present. The adoption of active phased array technology, through adaptive control of radar power and beam pointing, will also have an important impact on improving the survival and working ability of radar in electronic warfare environment. But radar is an active sensor after all. It must transmit signals with a certain power level to make it easy to be detected and countered. Reducing the startup time of the radar can reduce the vulnerability of the radar to electronic interference. Therefore, it is necessary to look for the least transmitted pulse and the most