我国首次利用光同步数字传输设备（SDH）进行超长距离数字图像信号传输获得成功，并开始用于公众通信网。光同步数字传输设备在长距离传输电视图像时，由低频抖动所引起的信号相位变化可能会对数字图像造成损伤，采用SDH设备传输数字图象目前只有极少数发达国家进行过尝试。此? For the first time in China, the use of optical synchronous digital transmission equipment (SDH) for long-distance transmission of digital image signals was successful and began to be used in public communication networks. Optical synchronization digital transmission equipment in the long-distance transmission of television images, the signal phase changes caused by low-frequency jitter may cause damage to digital images, the use of SDH equipment to transmit digital images At present, only a few developed countries have tried. this?