Protection Performance Evaluation And Analysis Of The Computer Interference

The computer system in the running status could radiate theelectromagnetic waves to outside which come from the host computer orperpheral devices and could carry the significant informations.Theseinformations may be intercepted by the aerial and analyzed by the means ofsignal processing for reproduction.So it is a work paid high attention thatavoiding the electromagnetic information leakage of the computers and ensuringthe security of the computer in the normal operating state.The computercountermeasuresset is a kind of device dedicated to avoid the electromagneticinformation leakage from computer.According to the principle of electronic countermeasure,it radiates thesynchronized interference signal with the computer,when the computer isrunning,in order to disguise the radiated electromagnetic information. Thispaper has mainly analyzed and researched sorts of computer countermeasuresset,and illustrate their virtues and defects through experimental data. And thenaiming at the special algorithm of one kind of computercountermeasuresset,which is used to product the pseudorandom sequence，weoptimize the algorithm to improve the protective properties.The main jobs of thepaper are illustrated as follow.First,explaining the different principles and work modes of various computercountermeasuresset,and illustrating the different kinds of computercountermeasuressets could be used in different occasions by comparison.Itprovides some special points and indicates to test and estimate the variouscomputer countermeasuressets.Second,testing the characters of electromagnetic pectrum radiated by allkinds of computer components when they are running,and analyzing theprinciple of computer electromagnetic information leakage.Then,according tothe related standards of GJB151A/152A,the thesis explains the main spectrumand frequency points on which the computer system products theelectromagnetic information leakage.At the same time it provides the basis for the key protective point of computer countermeasuresset.Third,establishing the experimental platform and settling the the method totest working performance of the computer countermeasuresset.Because the keypoints of various computer countermeasuressets are different,this paper hastested the frequency domain character of the noise computer countermeasuressetand the time domain character of the relative computer countermeasuressetrespectively.And it evaluate the advantages and defects about the two kinds ofcomputer countermeasuressets through the experimental data.Fourth,proposing a method that optimizes the producting pseudorandomsequence algorithm,according to the disadvantages of the current computercoherent countermeasuresset which produces the pseudorandom sequence.Thenew algorithm is made by the VC++6.0development environment on theWindows XP operating system.That prolongs the pseudorandomsequence’s.period which is produced by the coherent countermeasuresset,andimproves the randomness.For this sake, the protective character of the computercountermeasuresset is promoted.