Nowadays, space has become an important field that affects the military dominance of all countries, and the battlefield in space is controlled by communication satellites. However, military satellite communication has always been the focus of attention in this field because satellites are vulnerable to various attacks from the other side. The following is what I recommend to you, I hope you like it!

On the Interference of Military Satellite Communication

This paper mainly studies the anti-interference problems faced by military satellite communication system, analyzes its interference factors, briefly analyzes the anti-interference technology of satellite communication system, and designs an interference analysis and decision-making system.

Keywords: anti-jamming of satellite communication

Nowadays, space has become an important field that affects the military dominance of all countries, and the battlefield in space is controlled by communication satellites. However, because there is no closed area around the satellite, it can only be exposed to the air from beginning to end, and it is extremely vulnerable to various attacks from the other side. Therefore, the problem of interference and anti-jamming in satellite communication has always been the focus of attention in this field. In the following pages, the author will summarize the interference and anti-interference factors faced by satellite communication at this stage, and put forward his own superficial views on the interference and anti-interference problems.

I. Interference faced by satellite communications

As a special channel, satellite channel is composed of uplink and downlink. The interference to satellite communication system is usually carried out through these two links.

*** 1*** Interference on uplink

It is precisely because communication satellites are exposed in some orbits in the air that they are easily found by the enemy and interfered accordingly. Once the repeater in the uplink is disturbed, all users passing through this repeater will be affected.

***2*** Interference downlink

Because the antenna of the ground station is directional, in order to jam the communication satellite, the jammer must be close to the signal receiving ground station. For military satellites, different kinds of satellites are interfered to varying degrees. For strategic satellites, ground stations in various countries will set certain protective measures to make it difficult for the enemy to get close, so the jamming effect will be greatly reduced. For tactical satellites, the jamming effect will be stronger because they are close to the enemy.

* * * 3 * * Jamming satellites

If the satellite itself is disturbed, the whole satellite communication system will be paralyzed. Because the satellite is close to the earth station and jammer, the relationship between them is obvious, and the satellite antenna covers a wide range. Therefore, even if the antenna pattern is shaped, as long as there is enough EIRP in neighboring countries or high seas, the signals that interfere with the earth station can interfere with the satellites within the coverage of the satellite antenna.

Second, the anti-jamming technology of satellite communication

Because of the different interference sources in satellite communication, the influence on communication system is also different. Therefore, in order to ensure the normal implementation of satellite communication system, comprehensive measures must be taken to confront it.

* * * A * * Spread Packet Spectrum Technology

1. Direct sequence spread spectrum ***DS*** Anti-jamming

The direct sequence spread spectrum signal realizes the spectrum expansion package of the signal through the high bit rate spread spectrum code sequence, so that the power in the unit frequency band is smaller and the power spectrum density of the signal is lower. In this case, communication can make the other party ignore the existence of the signal under the cover of thermal noise and channel noise. At the receiving end, the same spreading code technology is used for despreading, so as to recover the spread packet signal. Because of the irrelevance between the interference signal and the spreading code, the receiver can realize the processing gain of the interference signal when despreading.

2. Frequency hopping anti-jamming

Frequency hopping technology is mainly used in military communication at present, which can effectively avoid interference and give full play to the efficiency of communication. Frequency hopping uses random hopping of carrier frequency to avoid interference in a bandwidth much larger than the signal bandwidth. If the other party wants to completely interfere with the signal, it must interfere with a considerable range in the whole bandwidth.

* * * Two * * vehicle-mounted processing technologies

Anti-jamming applications of spaceborne processing mainly include the following:

1. Frequency hopping on-board processing anti-jamming

The uplink uses frequency hopping anti-jamming signal, which is demodulated on the satellite, and then the data is asynchronous time division multiplexed, remodulated and forwarded on the downlink. According to different system requirements, decoding and recoding technology can be used on the satellite, and frequency hopping technology can be used to protect the downlink after modulation.

2. Direct sequence spread spectrum on-board processing anti-jamming

The uplink uses direct sequence spread spectrum anti-jamming signal, and despreads and demodulates it on the satellite. After asynchronous time division multiplexing, the data is remodulated and forwarded in the downlink. According to different system requirements, decoding and recoding technology can be used on the satellite, and direct sequence spread spectrum technology can also be used to protect the downlink.

3. Anti-jamming of hybrid spread spectrum on-board processing

Hybrid spread spectrum mainly uses frequency hopping anti-jamming signals in uplink. After the signal is transmitted to the satellite, it is de-hopped and demodulated on the satellite. Demodulated data is retransmitted in downlink after asynchronous time division multiplexing, remodulation and direct sequence spread spectrum. According to the different requirements of the system, decoding and recoding techniques can also be used on satellites.

4. Anti-jamming technology of vehicle-mounted intelligent AGC

Sman AGC is mainly based on the different characteristics of strong interference and direct sequence spread spectrum communication signal envelope, and realizes the suppression of strong interference through adaptive envelope transformation. When there is no interference in the uplink, it does not envelope the signal, which is equivalent to a linear amplifier; When strong uplink interference is detected, the envelope linear amplification area is shifted to the right, resulting in a zero area, so that most of the interference falls into the zero area and is eliminated, and the small signal part of overlapping enhanced interference is amplified, thereby improving the signal-to-noise ratio of the output.

Anti-jamming technology combining * * * three * * on-board processing and satellite-ground broadband frequency hopping

On the satellite, the uplink signal is de-frequency-hopped and demodulated, the signal is restored to a digital signal, and then re-modulated and frequency-hopped. The anti-interference ability of spaceborne processing transponder is greatly improved.

Third, the interference analysis decision-making system

Each satellite has its own anti-jamming system, and there are many anti-jamming systems on the same satellite. According to the actual situation, interference measures should be taken purposefully to achieve targeted anti-interference and achieve anti-interference effect. However, the effective resources of the system will be sacrificed after anti-jamming measures are adopted. Therefore, it is necessary to establish a satellite communication anti-jamming analysis and decision system to coordinate the anti-jamming system adopted by users in the network.

Signal detection and interception, signal analysis and identification, anti-jamming decision system and instruction issuing system constitute a complete anti-jamming support and decision system for satellite communication.

*** 1*** signal detection and interception: using software radio technology, RF direct sampling, digital down conversion and multi-rate processing are carried out. So as to achieve the purpose of receiving signals entering a satellite communication system or a transponder.

Analysis and discrimination of * * * 2 * * signals: Demodulate various modulation signals by using automatic identification technology of signal modulation mode. In order to complete the demodulation of various modulation signals and identify the enemies and friends of the signals.

* * * 3 * * Anti-jamming decision system: using the results obtained in the first two parts, when the system is interfered by the enemy, analyze the nature of the interference signal and determine the interference types * * * aiming interference, tracking interference and blocking interference * * *; The number and signal strength of the interfered transponders; The number of frequency bands of the interfered transponder; The numb of transponder resource that have not been disturbed. After determining the above contents, we can adopt the corresponding anti-jamming system, release the available frequency bands and frequencies, and decide which radio stations need to adopt anti-jamming means when communicating.

***4*** instruction issuing system: the communication system automatically switches to the corresponding anti-jamming working mode according to the instructions provided by the anti-jamming decision system.

References:

Talking about anti-jamming technology of satellite communication. Shi Weiping. Dual-use technologies and products. 20008+00.

[2] Anti-jamming technology and application of military satellites. Song Yongcheng, Yan Qihua. Electronic technology.2006.8+02

[3] Research on anti-jamming and invulnerability of new generation satellite communication system. Qiu Yonghong, Liang Tao, Yu Yong. Wireless communication technology. Issue 4, 2003.

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