Line-Encoding Standards
Line encoding is the technique used to insert electrical pulses on a medium—in this case, copper twisted pair—so that the receiver can interpret this accurately. The three standard line-coding techniques used in xDSL technologies are as follows:
Discrete Multi-Tone (DTM)
Quadrature Amplitude Modulation (QAM) (discussed in Chapters 4 and 5)
Carrierless Amplitude/Phase (CAP) Modulation
Discrete Multi-Tone
DMT is a method of coding information (line coding) to be transmitted over the physical phone line. The information is split into a number of subchannels, each characterized by the same bandwidth requirements but packaged to be transmitted at different frequencies. This technique has a number of advantages such as channel ...
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