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为了实现计算机视频泄漏信号的实时采集,设计了以USB2.0为双向传输通道的泄漏信息采集系统。针对视频图像场消隐期间无有效数据的特点,输入通道中外设以场为单位分块传输实时泄漏截获数据至主机。输出通道中主机将计算出的行、场同步信号通过USB传输至外设,外设由此产生高精度同步信号;该过程在输入通道的块间隙间进行,从而实现了实时双向数据传输。实验采集了行周期为15.625kHz、场频为50Hz的CCD视频信号和行周期为31.656kHz、场频为60Hz的计算机显示器视频信号,截获图像显示稳定,证明本系统方案切实可行。
In order to realize real-time acquisition of computer video leakage signal, a leakage information acquisition system designed with USB2.0 as bidirectional transmission channel was designed. According to the characteristic that there is no valid data during blanking of the video image field, the peripherals in the input channel transmit the real-time leakage interception data to the host in units of fields. The output channel of the host will be calculated by the line, the vertical synchronization signal transmitted to the peripheral USB, peripherals which produce high-precision synchronization signal; the process of input channel block interval between, in order to achieve real-time two-way data transmission. Experiments collected CCD video signals with a row period of 15.625 kHz and a field frequency of 50 Hz, and computer monitor video signals with a line period of 31.656 kHz and a field frequency of 60 Hz. The intercepted images showed a stable display, which proves that the system solution is feasible.