Stealth Communication Systems Research And Implementation Of Some Of The Key Technologies

Under the background of the current information, to improve the equipment,system and network in a complex electromagnetic environment of comprehensive combat effectiveness, should consider the stealth communication system’s ability to the anti-interference characteristic and the anti-intercept characteristic from the perspective of electronic. And the data link is one of the key technologies in the stealth communication system, because of its strong ability to the anti-interference characteristic and the anti-intercept characteristic, has become the focus research in the world at present.Through the survey found, mostly existing data link using coding, modulation, spread spectrum and frequency hopping technology to improve the ability to the anti-interference characteristic and the anti-intercept characteristic. For example, the US military’s Link16 data link has used RS coding technique to improve the anti-interference characteristic and with spread spectrum, high-speed frequency hopping technology to improve the ability to the confidentiality and the anti-intercept characteristic. But Link16’s biggest drawback is that the bandwidth is limited,it’s transmission rate has only three kinds of 28.8 Kbps,57.6 Kbps and 115.2 Kbps, and when the transfer of non-coding freedom message, the maximum transmission rate is only 238Kbps, that can not meet the needs of large-capacity data transmission. Noticed the Turbo code has advantage of high transmission rate, and can be based on user level to set different transmission rate, decoding performance close to the shannon limit, etc. The article uses the Turbo code instead of the link 16’s RS code, and combined with digital modulation, spread spectrum and frequency hopping technology to build a new stealth communication system,also select the system’s Turbo code technology and frequency hopping technology as a research object of this paper.First of all,on the basis of researching the stealth communication system, this paper set up a new stealth communication system combined with Turbo codes, digital modulation, frequency hopping and spread spectrum technology; Secondly, analyzing and summarizing the stealth communication system’s communication performance characterization parameters are communication performance and communication distance, and stealth performance characterization parameters are detecting distance and intercept probability. On this basis,depth study of the Turbo code’s encode and decode structure and the structure of frequency hopping. Through quantitative simulation analysis it is concluded that communication performance and stealth performance has a relationship of mutual coupling. Specific performance: Turbo code must increase the transmission power to improve the stealth communication system’s communication performance, but increasing the transmission power has reduced the system’s the ability of anti-interception, restricted stealth performance. And frequency hopping as the first choice of the intercept technology, there is no doubt of its effect on the stealth performance, but because the dehopping is in real time, Whether or not has completed the frequency hopping synchronization,it will dehopping, and thus, affect the system bit error rate, restricted the communication performance; Finally, according to the requirements of the transmitter stealth communication system design,this paper has designed and implemented Turbo code’s encoder module and transmitting terminal’s frequency synthesizer in frequency hopping’s module in the FPGA platform.