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相片传真通信过程中,寄生信号往往对弱传真信号或记录图片低电平(黑、灰)处造成干扰。出现干扰时,往往图像信号不稳、信噪比下降、干扰花纹或斑点不规则。对低频寄生信号干扰,可在记录图片上数出干扰条纹,根据经验公式f(?)=MN/60(Hz)估计干扰频率,判断干扰源。上式中 M 为一条扫描线内的干扰条纹数,N 为滚筒每分钟转数,f_r 为干扰频率。而较高频率(高于200Hz)的寄生信号干扰,则很难用此法估计干扰频率。但此时干扰图形往往有明显的特征可寻,多数情况以不规则的条纹、花纹为主,
Photo fax communication process, the parasitic signals tend to weak fax signal or record picture low (black, gray) at the interference. In the event of interference, often the image signal is unstable, the signal to noise ratio is reduced, interference pattern or irregular spots. For low-frequency parasitic signal interference, interference patterns can be counted on the recorded pictures and the interference source can be judged according to the empirical formula f (?) = MN / 60 (Hz) to estimate the interference frequency. Where M is the number of interference fringes in a scan line, N is the revolutions per minute of the drum, and f_r is the interference frequency. The higher frequency (higher than 200Hz) parasitic signal interference, it is difficult to estimate the interference frequency using this method. However, the interference pattern often has obvious features to be found at this time. In most cases, irregular stripes and patterns are the main features.