Research On Telecommand System Of Twice Civil Air Defense Alarm Based On Spread Spectrum

Civil air defense alarm system was a system to dispense antiaircraft alarm sig-nal,hand hostile air attack informational communication to urbanite at wartime.It is a particular informational communication system of the civil air defense depart-ment,and can not be taken place.At the development trend of digitaliza-tion,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 as 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, world renowned chip manufacturer pushout respective products one after another,the kinds of which are too many to statiste. All above these supply favourable technical base and realize condition for the remodel of civil air defense alarm system.The design on twice civil air defense alarm system in this paper adjoint spread spectrum technology and SCM technology based on spread spectrum communication theory to realize remodel of once cvivil air defense alarm system. This paper depend on STANFORD TELECOM corporation's new spread spectrum chip and Intel corporation's 87C196 SCM,designing correlation peripheral interface circuit and software Model Block.First of all, this paper designs the twice civil air defense alarm system's digital spread spectrum communication with STEL-2000A. When the cur-cuit resets,the chip remains accepting state,works in burst mode,and adopts DPSK modulation mode.It proceeds quadrature-sampled intermediate frequency signal after the AD9057 has converted,then down-converses,despreads and demodulates.The demodulated baseband signal will be sended into SCM to dispose through interrupt. If the chip remains sending state,it will take the data spread spectrum and modu-late,then sent forth by AD9768.The chip can be controlled through writing data in theinterior 87 registers.Secondly,this paper designed control system of twice civil air defense alarm system.Because the SCM 's port number was limited and port driving power is feebleness, this design realizes nixie tube's Display drive with keyboard management chip MAX7219 and realizes true time display with DS1302,which can economize SCM I/O port and make circuit connection simplicity. Then this paper presents the software flow, divide the realization of the system into different function modules for the purpose of software maintenance and amendment.The paper also gives an outline of some means of debug and software antijamming measure. Finally,we simply debate the design of system power supply.