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传送PCM信号所需要的带宽,在基带传送时为传送速率的0.5～1倍(BT=O.5～1)。对于PAL电视信号的传送,若取样频率为3f_(?)=13.3MHz(f_(?)为彩色副载波频率)、量化比特数为8时,传送速率为106.4MHz,需要有60～100MHz的传送带宽。这一数值与直接以模拟信号形式进行基带传送时的6MHz带宽相比,为其10～20倍。这正是数字传送方式发展缓慢的原因之一,从而促进技术人员研究如何压缩频带,设法消除电视信号中信息的冗余成分,以节省传送频带。
The bandwidth required to transmit the PCM signal is 0.5 to 1 times the transfer rate (BT = 0.5 to 1) at the time of baseband transmission. For the PAL television signal transmission, if the sampling frequency is 3f _ (?) = 13.3MHz (f_ (?) Is the color subcarrier frequency), the transmission rate is 106.4MHz when the number of quantization bits is 8, bandwidth. This value is 10 to 20 times larger than the 6 MHz bandwidth when transmitting baseband directly in the form of an analog signal. This is one of the reasons for the slow development of the digital transmission method, thereby facilitating the technical staff to study how to compress the frequency band and try to eliminate the redundant information in the television signal so as to save the transmission band.