hertz and 3,400 hertz, corresponding to a bandwidth of 3,400 - 300 = 3,100 hertz. The spectral efficiency or modulation efficiency is 56,000/3,100 {{=}} 18.1 (bit/s)/Hz downstream, and 48,000/3,100 {{=}} 15.5 (bit/s)/Hz upstream.

Upper Bound

An upper bound for the attainable modulation efficiency is given by the Nyquist rate or Hartley's law as follows: For a signaling alphabet with M alternative symbols, each symbol represents N = log₂ M

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