Study On The Physical Layer Waveform Jtids System

With the rapid development of information technology, modern warfare has become an information war, the bout of the joint battle and synthetical strength. The information battle has become the focus of the war. The one who can maintain continuous reliable communication in the harsh electric interference environment will win in the war. In order to gain the inititive in the increasingly harsh battlefield environment, it demands a comprehensive control of the battlefield situation and shortens the time of decision making, taking various anti-interference measures, maximizing the combat effectiveness of the mechanized weapons platforms and the cooperative engagement capability of the participating units.In modern battlefield environment, the communication system signals transmission environment is becoming worse, the channel performance is not only subject to additive noise and the impact of the non ideal channel transmission characteristics and also subject to more and more deliberately malignant electromagnetic interference. In this harsh environment, the communication equipments must adopt various effective anti-interference measures to guarantee information transmission, processing, distributing timely, effective and security. Joint Tactical Information Distribution System, called JTIDS, is a coordinated system of navigation,communication,recognition developed by US army for the purpose of suiting the joint operations and getting active in the war. Its physical-layer waveform, which has strong anti-interference ability because of using RS coding,soft spread-spectrum,high-spread frequency hopping,time-hopping etc, is the main information transmission waveform in the modern hi-tech warfare. In order to meet the future needs of high-tech information warfare, it is necessary to carry out a physical-layer of JTIDS waveform in-depth study.The basic principles of the JTIDS, focusing on its network structure,message type and data packet formats, is firstly introduced, thus the overall concept of the system is established.Then the physical layer waveform transmission model of the system is set up analyzing detailedly the key technology of the physical layer waveform, on that basis the influence of a single pulse transmission,dual-Pulse Transmission,CCSK coding and RS coding on the anti-jamming performance is mainly studied in case of Gaussian noise,broadband noise and partial-band interference from the analysis of bit error rate point of view by simulating with Matlab. So the conclusion is that at BER 10?5 a coding gain of about 2.3 dB is brought by the use of RS coding, a CCSK soft spreading gain of about 8 dB is brought, the single-pulse structure underperforms the double-pulse structure by about 3dB in terms of average energy per bit per pulse. Finally from the further improvement of the system performance point of view, three kinds of ways , such as new CCSK codes,orthogonal codes,dual-orthogonal codes, is analyzed and simulated by Matlab, the conclusion is that the system performance with dual-orthogonal codes outperforms that with new CCSK codes and orthogonal codes, but the demodulation complexity is higher than the waveform with new CCSK codes, but lower than the waveform with orthogonal codes.