Research On Security And Guard System For The Transmission Of Digital TV Signal

In recent years, the events of illegally attacking video network of digital TVoften occurred. Events such as the attack on the digital TV video network carried outby Falun Gong cult of Jilin Province attacked the attack on Sinosat II satellite carriedout by Taiwan and other overseas Falun Gong cult and so on bring baneful influenceto the country and society. Research on digital TV signal’s transmission securitysystem has great theoretical significance and practical value on ensuring safebroadcast and that decisions can be carried out without fail.This paper studies video network prevention technologies so as to realize thedigital TV content security and proposes a new security and prevention systemarchitecture for digital TV signal’s transmission. In order to reduce the amount ofembedded watermark data, we propose an image wavelet domain watermarkingalgorithm based on the compressed watermark information. Concerning with thecharacteristics of digital TV video compression, a novel video watermarkingembedded method is proposed and proved to have good effort through practical tests.The main research content of this thesis is manifested in the following threeaspects:(1) An image wavelet domain watermarking algorithm based on compressedwatermark information is proposed. The watermark image is concentrated throughthe refining process and skeleton scaling technology so that the amount of watermarkdata embedded is reduced. The compressed watermark is embedded into the lowfrequency approximation system LL3after three scales wavelet decomposition of theimage and can be extracted through the inverse process. Simulation experimentsshow that the embedded watermark in the algorithm has good invisibility and strongrobustness. The watermark can still be extracted after filtering attack, noise attack,image compression attack, shear attack and other attacks.(2) A new video watermark method is proposed. For digital TV video, a newvideo watermark is compressed and embedded into the unchanged areas of I frame of the video GOP. This method only consumes calculating resources in theembedding process and does not incur extra expense during the transmission andbroadcast process of digital TV video stream. Such method does not increase theamount of computation in the decoding process and hence is more suitable forterminals with weak computing abilities such as STB. Since the region embeddedwatermark is the unchanged areas of I frame, all subsequent frames decode accordingto this I frame in the GOP and therefore we can detect watermark in all subsequentframes. Through simulation experiments, we prove that the algorithm ensures thatthe embedded watermark has good invisibility and balances the requirement betweenthe invisibility and the calculating expense.(3) We propose a novel security and guard architecture for the transmission ofdigital TV signal. From the digital TV signal source perspective, the architectureadopts the composite watermark technology which utilizes strong robust watermarkand fragile digital watermark. The architecture can distinguish the legitimate signalfrom the illegal signal and provides effective security and guard technologies for thesignal flow. In the architecture no blind spots safety detection is realized in the wholedigital video network. When detecting illegal attacks, the architecture can cut off theillegal source in real time, accurately locate the accident network position and alarmautomatically. Furthermore, the digital TV security classification and disposalplatform established in the thesis can realize the all-weather real-time emergencyresponse. Finally, in the practical environment of a particular scope of a prefecture-level city, a secure and guard system and related simulations are built up and realized.It is proved that utilizing digital watermark technology to secure all processes ofvideo networks is effective and practical.