Special Communication System

1、Wireless Beyond Visual Range Communication (1)Meteor Trails Burst Communication

The first generation of MBC (Meteor Burst Communication) system including the five equipment types from HX-101A to HX-101E was developed by School of Telecommunications Engineering of Xidian University, and got the National Science Conference Award in 1978 and the second prize of Scientific Research Award of electronics industry ministry in 1983. Since the late nineties, two generations of MBC have been studied by the School. Based on adaptive broadband transmission technology the latest generation of MBC system has great performance to guarantee the requirements of the emergency communications.

As a strategic communication system, MBC system can work steadily over long distance under severe conditions such as nuclear explosion, earthquake, etc. In military applications it is developed for the Minimum Essential Emergency Communications Network. In additional, it can be useful in a number of civilian applications, especially remote sensing where it can provide inexpensive communication techniques for hydrometeorological data collection, polar exploration, Natural disaster warning, etc.

  (2)High capacity MIMO-OFDM communication system integrating microwave and scattering technologies

Meeting the microwave BVR large capacity demands, this system has achieved reliable transmission in a 4 transmit and 4 receive antennas MIMO and OFDM system with a spectral efficiency of 2-8 bps/Hz and been accepted by national ministries. The technical index has reached domestic advanced level. It has obtained 2 national invention patent grants and 17 patent applications.

The system has several advantages including large capacity, good mobility, large coverage area,and anti-nuclear explosion, etc. In civilian applications, it can be widely used in the industrial departments such as electric power, oil, mining, and water conservancy as scheduling system. It can also be used for the forest fire prevention, emergency rescue and disaster relief as emergency communication system. In additional, in military applications, it has been used to establish strategic and campaign communication route. 2、Satellite covert communications and onboard switching

By using key techniques such as M-ary spread spectrum, significant achievements have been obtained in satellite covert communications. A satellite covert communication prototype was developed and tested through the real satellite link. It successfully passed the authoritative department inspection and appraisal of achievement of technology, and the research is in the leading domestic level.

An onboard switching architecture based on orthogonal time-division multiplexing ( OTDM ) non-regenerative on-board processing was proposed, and it supports on-board processing and switching with a very low complexity. An integrated anti-jamming satellite communication system prototype based on this architecture was successfully developed. It passed the acceptance test and technical achievement appraisal organized by the Ministry of Aeronautics and Astronautics and the Ministry of Industry and Information separately. This achievement is recognized as the international initiative technology, and it has reached the leading domestic, international advanced level.

It is acknowledged by authoritative experts that the invention opens up new roads for the wide application of on-board processing and switching in satellite communications. Four national invention patents, more than 10 SCI indexed papers, and 50 EI indexed papers have been published.. The research results can find wide applications in satellite payloads and other applications.

Satellite covert communication prototype

Satellite communication prototype based on OTDM non-regenerative on-board processing3、Wireless Laser Communication System

Wireless laser communication (WLC) system is a point-to-point directional communication system, which is based on the laser-beam’s line-of-sight propagation in space. At present, a series of prototype of wireless laser communication link system have been realized, which adopt a lot of advanced techniques such as double transmit diversity, large aperture aspherical len receiving antenna, large photosensitive surface photodetector. Moreover, using burst transfer technique combining with ARQ, reliable full-duplex information transmission based on IEEE802.3 MAC frame and TCP/IP protocol has been accomplished. The research achievement can be used in wireless broadband access, links between mobile communication network base stations, emergency communication instead of fiber cable, military communication, etc.











The type C prototype experimenting in communication at a distance of 10 kilometers

4、HF Communication System (1) HF Automated Frequency Selection Communication System

This system has implemented the functionality of real-time dynamic automated best working frequency selection and assignment within the whole HF frequency range, and the transmission of voice and data. The system has not only solved the difficult problem of mobile communication frequency selection for XX system, but also provided a fast and reliable way to ensure smooth communication coordination in XX system.

The system involves several techniques such as long-term HF frequency prediction, automatic link establishment (ALE), modulator/demodulator (MODEM). The system has several functions: frequency management, voice and data transmission.

Currently, the HF automated frequency selection communication module has been widely installed in the XX system. As one of the HF frequency selection communication equipments, the system has been used in the communication support and guarantee for almost all the visit missions of XXXX fleet since 1999, as well as in many important military exercises, including the current Chinese naval fleet escort mission in the Gulf of Aden.

This project passed the technical evaluation organized by the CDNH (Communication Department of Navy Headquarters) in 1999, and won the Military Second-Class Science and Technology Progress Prize awarded by the General Staff of PLA.

(2) Frequency Management System of **HF Communication

This system is part of the XX Project, which is led by the NO.7 Research Institute of CETC(China Electronics Technology Group Corporation). Our university is responsible for the research and development of the automated frequency selection communication module. The tasks of this module include the establishment of frequency management link between the detection transmitter (coast BS) and the detection receiver (BS on board), adaptive link establishment, and the transmission of frequency management data. The system has passed the technical model evaluation and has been formally installed in the XX system since 2006.