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北京邮电学院电信工程系王德隽教授、赵振纲讲师等研制的《数字多频记发器信号收、发系统》,于1987年4月11日通过院级评审。多频记发器,用于市话局间,长话局间,长、市话局间传送记发信号。国内目前实用的多频信号发、收系统主要采用模拟电路技术。这种系统的主要缺点是所需滤波器数量多、体积庞大,而且性能指标不易全面达到国标或 CCITT 有关建议。特别是可靠性及抗单频干扰
Beijing Institute of Posts and Telecommunications Department of Telecommunications Professor Wang Dejun, Zhao Zhenlin Lecturer and other research and development of “digital multi-frequency signal transceiver system, hair,” in April 11, 1987 through the hospital-level review. Multi-frequency generator, for the local telephone exchanges, long-distance office, long, local office to send and send signals. At present, the practical multi-frequency signal transmitter and receiver system mainly adopts analog circuit technology. The main disadvantage of this system is the number of filters required, bulky, and performance indicators are not fully meet the national standard or CCITT related recommendations. Especially the reliability and anti-single-frequency interference