"As an important pillar of military strategy, aircraft carrier battle group is an effective force to show national strength, support foreign policy, ensure national interests and stop crises and conflicts. Aircraft carrier battle groups can implement force deterrence through rapid deployment; In wartime, it can carry out tactical or strategic nuclear / non nuclear attacks on enemy deep targets at sea and on land. For such a large system, the problem of how to cooperate, how to communicate and how to locate has actually become quite complex.
With the development of national economy and the rapid development of machinery, materials, electronics, power, nuclear energy, communication and other technologies, our navy has developed very rapidly.
Ten years ago, I was on a business trip in a submarine. At that time, a Navy monitor asked a technical expert, "what is the strength of our navy?" Although the expert put it mildly, the core meaning is: no matter how many submarines and warships we have, if we can not form an aircraft carrier battle group, it is difficult to integrate into a maritime group army, and it is difficult to form a frontal battle with an aircraft carrier battle group like the US Army.
As an important pillar of military strategy, aircraft carrier battle group is an effective force to show national strength, support foreign policy, ensure national interests and stop crises and conflicts. Aircraft carrier battle groups can implement force deterrence through rapid deployment; In wartime, it can carry out tactical or strategic nuclear / non nuclear attacks on enemy deep targets at sea and on land.
Aircraft carrier
One to three aircraft carriers. It can range from simple display of force to attacks on various targets. The aircraft carrier also eliminates the need for aircraft to worry about using airports, waterways and airspace of other countries. Aircraft carriers can also provide long-term support from other forces.
Cruiser
One or two missile cruisers. At present, it is a Ticonderoga class cruiser equipped with Aegis system. As the escort center of the aircraft carrier battle group, the cruiser provides a variety of combat capabilities such as air defense, anti-ship and anti submarine. At the same time, it is also the flagship of the whole aircraft carrier battle group. The ship also has Tomahawk cruise missile, which has the ability to strike ground targets from a long distance.
destroyer
Two or three missile destroyers. These destroyers help cruisers in the fleet expand the scope of the defense circle, and are used for air defense, anti submarine and anti-ship operations.
frigate
A frigate.
submarine
One or two attack submarines. Submarines are used to support the fleet's vigilance and operation against surface or underwater targets. It can also use its submarine launched Tomahawk cruise missile to attack land targets.
Supply ship
One to three supply ships.
Today, the attack and defense capabilities of an aircraft carrier battle group are very complex. Generally speaking, fighter planes, attack aircraft, early warning aircraft, anti submarine aircraft or helicopters carried by aircraft carriers are used to attack, defend or search the enemy hundreds of kilometers away from the aircraft carrier. The first task of other combat ships is to protect the operational safety of aircraft carriers.
For such a large system, the problem of how to cooperate, how to communicate and how to locate has actually become quite complex.
We divide the problem into surface and underwater.
On the water surface, the main problem is radar:
We need to find each other's warships, aircraft and other surface equipment in time, and hide ourselves at the same time. This is actually the Navy's radar warfare. Before the missile and artillery clash, the electromagnetic waves clash first.
Naval radar countermeasure
Naval radar countermeasure refers to the use of active and passive methods to implement electronic jamming against the receiving system, display system and automatic tracking system of enemy naval radar. It includes active jamming, passive jamming and combined jamming.
Active jamming
Active jamming technology uses jammers to transmit jamming signals of certain waveforms to disrupt and deceive enemy radars. Active jamming is generally divided into noise jamming and deception jamming.
Noise interference is also called suppression interference. It conceals or engulfs the target echo on the enemy radar fluorescent screen by transmitting high-power noise signals, so that the enemy radar can not work. Deception jamming is to deceive the enemy with jamming signals. Deception jamming allows the enemy radar to see the target, but it can not obtain the accurate information of the target, but can only obtain the distorted parameters such as range, azimuth and velocity. The false echo similar to the real target is displayed on the fluorescent screen of the enemy radar.
At present, the naval radar jammer implementing active jamming can cover the electromagnetic frequency domain below 20 GHz, its response time is 1 ~ 2 seconds, and the clutter jamming power can be as high as megawatt. The most advanced jammer can jam 80 targets at the same time.
Passive jamming
As the name suggests, passive interference is a kind of interference that does not radiate electromagnetic energy. Common passive jamming to radar mainly includes the following two methods:
Launch or drop various chaffs and reflectors made of materials that can reflect electromagnetic waves to form interference with enemy radar. For example, after the explosion and divergence of a single chaff bomb, an air interference cloud of 1000 ~ 3000 square meters can be formed in 3 ~ 5 seconds and can be suspended for 10 minutes, so as to cover the real target (i.e. our ship or shipborne aircraft) that the enemy radar wants to capture or lure the enemy radar to track the false target (i.e. interference cloud).
The stealth design of ship (or shipborne aircraft) shape and structure and the target stealth methods such as coating materials absorbing electromagnetic waves on the surface of ship (or body) are adopted to weaken the reflection of electromagnetic waves from the target, so that it is difficult for enemy radar to find the target. For example, the "Lafayette" class frigate has adopted a series of stealth measures, such as streamlined shape design, superstructure outer wall inclined by 10 °, ship body painted with microwave absorbing paint, which has reduced the radar reflection area of this class of ship by 60% compared with the traditional design and achieved good stealth results.
Combined interference
Combined jamming is the combination of the above various jamming. Not only several active jamming can be combined properly, but also active jamming and passive jamming can be combined to give full play to the best jamming effect. For example, the effective power of American an / alq99d and an / alq99e jammers is up to 10 kW, which can effectively jam all marine radars working in the frequency domain of 30 MHz ~ 18 GHz and the distance range of 200 ~ 300 km, such as early warning, altimetry, guidance, monitoring, gun aiming and guidance; They were used together with a variety of passive jamming equipment with excellent performance, such as an / ale43 shipborne aircraft chaff cutting and dropping device, an / ale40 chaff and tracer projectile launcher, and achieved good results in the Gulf War. The task of naval radar anti reconnaissance radar anti reconnaissance is to make our radar signal not or difficult to be intercepted and recognized by the enemy reconnaissance receiver, and it is not easy to be copied even if it is recognized by the enemy. The methods of naval radar anti reconnaissance mainly include:
Hide the main radar in peacetime, use it only in wartime, and try to shorten the startup time of shipborne radar.
In radar signal design, pseudo noise signals that are not easy to be recognized by enemy reconnaissance receiver shall be used, including pulse frequency modulation signal, in pulse pseudo-random coding signal and pseudo-random repetition frequency signal.
Low probability of interception technology is adopted. This technology can reduce the ratio of the operating range of the enemy reconnaissance receiver to the operating range of our radar (i.e. interception probability), so that the enemy reconnaissance receiver can not intercept our radar signal beyond the operating range of our radar detection target. For example, pilot navigation and sea search radar in the Netherlands is such a low probability of interception radar. The radar adopts FM continuous wave transmission mode. Although its output power is only 1 MW ~ 1 W, its operating range is roughly the same as that of conventional radar, and has excellent characteristics of "Silence" or "concealment" with low interception probability.
Frequency agility method is adopted. Random fast frequency hopping is an important and effective means of radar anti reconnaissance. The number of pulses required for frequency aiming of modern jammers is decreasing. By the early 1990s, the performance level of jammers has been improved to complete frequency guidance within 1 ~ 3 pulses. However, as long as the frequency hopping speed of the radar is fast enough (such as inter pulse frequency hopping) and the frequency hopping range is wide enough, it is very difficult for the jammer to reconnaissance and track the radar.
Adopt bistatic or multistatic working system or passive positioning mode. When the bistatic or multistatic working system is adopted, since the transmitting and receiving bases of our radar are divided into two places, the enemy reconnaissance receiver can only intercept and track the signals from our radar transmitting station, but it can neither reconnaissance nor jamming the radar receiving station on the ship. If our radar transmitting station is set up in a satellite or air flying shipborne aircraft or a closely guarded rear naval base, it will undoubtedly greatly enhance the anti reconnaissance and anti anti-jamming capabilities of our radar transmitting station. The passive location method is to determine the parameters of the target by inducing the enemy target to start the jammer or using the electromagnetic signal radiated by the target itself, so as to prevent our radar from being reconnaissance.
Naval Radar Counter countermeasure
Radar anti-jamming is radar anti-jamming. The technical measures can be divided into two categories: one is to eliminate the enemy's interference as much as possible, weaken it and improve the useful signal level before it enters our radar receiver; The other is to use the difference in waveform, spectrum and other structures between jamming signal and useful signal after enemy jamming enters our radar receiver, so as to suppress jamming and extract enemy target information from jamming background. Naval Radar Counter countermeasures mainly include:
Power confrontation. The simplest way to improve radar anti-jamming capability is to increase the transmission energy as much as possible. When the peak power is certain, in order to obtain higher average transmission power, pulse compression method is needed, that is, transmitting wide pulse signal, and outputting narrow pulse signal after receiving and processing echo. This not only increases the radar range, but also improves the radar resolution. This method has certain anti deception. The shipborne empar phased array radar being developed in Italy. Active jamming capability.
Monopulse angle tracking. Monopulse radar can determine the angular position of the detected signal source according to the information extracted from a single pulse echo, so it makes many radar countermeasure technologies for jamming beam sequential scanning radar almost completely ineffective.
Pulse repetition rate agility. This is a radar anti-jamming technology used to reduce the jamming efficiency of false targets at short range. The radar whose pulse repetition rate changes or jitters can jitter the non-human periodic external reflection echo and the periodic reflection echo signal sent by the electronic jamming system, so as to identify these signals as false targets. Unless the periodic characteristics of pulse repetition frequency jitter of radar can be determined in advance or its own position is between the radar to be interfered and the protected real target, it is difficult for electronic jamming system to make false target jamming effective.
Moving target display, moving target detection and their compatibility with frequency agility. Moving target display is a technology that uses the Doppler frequency shift of moving target echo signal to eliminate the interference of fixed target echo, so that the moving target can be detected or displayed. Moving target detection is a technology developed on the basis of moving target display. It can separate useful targets and clutter in frequency domain and reduce the interference of background clutter. These two technologies are effective measures against passive interference. However, in modern radar countermeasures, chaff jamming and aiming noise FM jamming are often used at the same time, which requires the use of moving target display (or moving target detection) and frequency agility to resist the above two kinds of jamming. At present, more typical compatibility modes have been studied: pulse group frequency agility? Intra group moving target detection; Random frequency agility? Co frequency moving target display; Four pulse system; Intra pulse diversity - pulse group moving target detection, etc.
Ultra low sidelobe antenna, sidelobe blanking and sidelobe cancellation. The ultra-low sidelobe antenna is designed to minimize the probability of radar detection in the sidelobe direction. The radar with ultra-low sidelobe antenna can implement spatial selection to limit the interference to the main lobe range; In other angle ranges, the radar can work normally and measure the angle information of the jammer, and then use the multi station positioning technology to measure the distance data of the jammer. Sidelobe blanking is also a technology to deal with sidelobe interference. It uses an auxiliary antenna whose gain is less than the main lobe gain of the main antenna and greater than the side lobe gain of the main antenna. Compare the output signals of the receivers of the main and auxiliary antennas: if the signal of the receiver of the main antenna is large, it is the signal when the antenna is aligned with the target, which enters the signal analysis circuit through gating; If the signal of the auxiliary antenna receiver is large, it is the signal entering from the side lobe. It is not gated and cannot reach the signal analysis circuit. However, the above sidelobe blanking technology can not deal with continuous wave or noise interference, so it is necessary to use sidelobe cancellation technology. The method is to detect the signals in the main and auxiliary receivers. If the signal power level of the auxiliary antenna receiver is large, cancellation processing shall be carried out, that is, the amplitude and phase of the interference signal shall be adjusted in a closed loop through the cancellation feedback circuit to minimize the interference signal in the main receiver channel.
Phased array system. Because the phased array antenna is composed of independent radiation units or subarrays, it can obtain the best adaptive antenna pattern in the electronic countermeasure environment. The digital beamforming receiver of phased array radar is a device that uses digital technology to realize instantaneous multi beam and real-time adaptive processing. While forming instantaneous multi beam, it can adaptively zero the interference source and obtain the performance of ultra-high resolution and ultra-low sidelobe. Therefore, it can deal with advanced comprehensive electronic interference very effectively. In addition, the waveform and locking time of phased array radar can be adjusted according to the requirements of clutter environment. Therefore, phased array is undoubtedly an excellent anti antibody system for naval radar.
Radar reconnaissance is a kind of electronic reconnaissance. The mission of naval radar reconnaissance is to use the electronic support measures and equipment of naval ships and shipborne aircraft, such as various radar reconnaissance receivers, to detect the electromagnetic radiation signals of potential threat radars at sea in peacetime, and find out their technical parameters, such as radar frequency and azimuth, so as to provide tactical basis for countermeasures and jamming in wartime; In wartime, it assists the satellite borne and airborne electronic support measures and equipment to carry out panoramic monitoring of the sea and air, find out the type, quantity, configuration, deployment and changes of various enemy electronic equipment, give an alarm through threat identification, and guide the shipborne anti radiation missile to carry out a destructive attack on the enemy's radar (together with its ship or aircraft).
The above mission is facing increasing challenges in the following aspects:
The unusual complexity and density of modern electromagnetic environment. For example, during the Gulf War, the U.S. military tested the electromagnetic signal of theater electronic warfare and found that the signal environment density was as high as 1.2 million to 1.5 million pulses per second. In addition, radar signals, communication signals and other electrical signals are usually mixed in electromagnetic radiation signals.
Contemporary naval operations mainly occur in the offshore environment, which is a high noise environment. The electromagnetic signals transmitted offshore not only include signals from friendly forces or Chinese cubic forces, but also various civil and military signals from the ground, sea and air.
The continuous enhancement of electronic anti reconnaissance and anti countermeasure (jamming) characteristics of enemy radar in system and technology increases the complexity and difficulty of naval radar reconnaissance.
Under the bad weather and propagation conditions in the theater or when there is enemy electronic jamming, naval radar reconnaissance will become more difficult. Therefore, the naval radar reconnaissance receiver must have high sensitivity, interception probability and strong sorting and processing ability to analyze and identify the real threat signals and judge their types and threat levels; In addition, we should also determine the nature and action intention of the target and determine the measures we should take according to its quantity, work situation and distribution situation.
At present, the world's advanced naval radar reconnaissance receiver has an interception probability of up to 100%, and can intercept electromagnetic waves with complex signal modulation in the frequency range of 0.5 ~ 40 GHz. The air interception distance is greater than the radar detection distance, the sea interception distance is greater than the sight distance, and the fastest signal interception time is tens of nanoseconds.
The development of naval radar electronic warfare focuses on the development of naval radar anti countermeasure technology, mainly including: automatic reconnaissance and warning; Phased array radar; Over the horizon radar and dual
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