The Object Of Jtids And Its Interference With Performance Analysis

Joint Tactical Information Distribution System (JTIDS) serving in the U.S. military is a coordinated system of communication, navigation and identification developed by US military for the purpose of suiting the combined operations of the sea, the land and air force. It is a high capacity, excellent privacy, jam-resistant tactical communications system. In the modern war it played a major role, for example, Gulf War, Kosovo War, etc. In modern warfare if the data communication between the fighter or reconnaissance aircraft of enemy is disturbed, we will successfully paralyze the enemy operational system or reduce operational effectiveness, then win the war. So it is useful and necessary to study the Joint Tactical Information Distribution System and methods of effective jamming.The main work includes three parts: 1. The working principle of JTIDS systems, communication technique, structure of information and operating parameters are researched. 2. The model of the data link of the system is built. 3. The evaluation of jamming effectiveness is analyzed.Firstly, the slot structure, communication techniques, the mode of transmission, the types and formats of message, packaging structure, the theory of the most effective jamming and the kinds of jamming are studied. JTIDS system have ability of jam-resistant by adopting a series of techniques of channel coding, direct sequence spreading spectrum, frequency hopping, interleaving and double pulse.Secondly, the key technology of JTIDS-soft spread spectrum, frequency hopping, channel coding, MSK modulation and demodulation is designed. The data link is built based on standard double-pulse package structure of fixed message format, including the modulation of the signal, channel transmission and statistic of the Bit Error Rate. What's more, the performance of the system in the Gaussian white noise channel is evaluated. The results show that DS and FH have a good ability of anti-noise, RS has a strong capability of error correction, and JTIDS system has excellent performance of anti-noise.Finally, because the jamming of frequency tracking and transmit jamming are invalid for JTIDS, then broadband jamming for JTIDS is researched by joining the jamming model into the system. The multitone jamming, noise frequency modulation, line frequency modulation, the combination jamming of sawtooth frequency modulation and pseudo noise sequences MSK modulation are modeled and analyzed to find parameters which affect the jamming effectiveness. The conclusion that the best bandwidth or the number of frequency of jamming is choosed by the ratio of jamming to signal is get. What's more, the jamming effectiveness of these four jamming is compared and analyzed. The conclusion that the comb spectrum broadband jamming is adopted to interfere the JTIDS is proposed.