Research On The Qingdao Civil Air Defense Alarm Key Technology Based On Spread Spectrum

Civil air defense alarm system was a system to dispense antiaircraft alarm signal, handhostile air attack informational communication to urbanite at wartime. It is a particular informational communication system of the civil air defense department, and can not be taken place. At the development trend of digitalization, unitization, integration of civil air defense communication, the civil air defense alarm system is developing too. for adaptation to the require of both future war and peaceful dual, and enhancing civil air defense communication system's directing automation. In recent years, development of different kinds of communication, technology infuses new clearly energy into communication, especially spread spectrum communication, because of its strongly interference-free feature, invisibility best, realizable code division multiple access and antimultipath wane and so on merit, gets extensive use at wireless region; the corresponding spread spectrum chips emerge sa the times and get boom, which provides advantage to realization of the circuit of spread spectrum communication. At the same time, in company with the advance of electronics level, the single chip microcomputer has a great development, All above these supply favourable technical base and realize condition for the remodel of civil air defense alarm system.In this paper, pseudo-random sequence the most critical technology in spread spectrum communication was discussed deeply. By analyzing, comparing and improving prime number sequence, m-sequence and Gold-sequence, a kind of appropriate improve m-sequence has been selected. Single-chip memory can't satisfy requirement, because digit procreanted by pseudo-random sequence is too long, so we must select appropriate chip to expand memory power of system in order to achieve the requirements of siren. The key chip of the system, that is CC1100, The Circuits of both transmitting side and receiving side has been designed, the communication protocol of both sides has been improved. Thus enhancing the security and the reliability of the civil air defense alarming system.