The capacity of PCM voiceband channels

It is theoretically shown that the capacity of a voiceband channel operating through a digital network is at least 56 kbps (for a 3.5 kHz baseband bandwidth). The capacity may actually be higher but how close one can come to 64 kbps, the limit imposed by the digital network itself, is unknown. The t...

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Bibliographic Details
Main Authors: Kalet, I., Mazo, J.E., Saltzberg, B.R.
Format: Conference Proceeding
Language:English
Subjects:
Amplitude modulation
Bandwidth
Baseband
Detectors
Phase change materials
Pulse generation
Pulse modulation
Pulse width modulation converters
Sampling methods
Signal generators
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Summary:It is theoretically shown that the capacity of a voiceband channel operating through a digital network is at least 56 kbps (for a 3.5 kHz baseband bandwidth). The capacity may actually be higher but how close one can come to 64 kbps, the limit imposed by the digital network itself, is unknown. The transmission method is based on generating nonuniformly pulsed PAM (pulse amplitude modulation) signals which at the network sampling instants go through one of the slicing levels of the A/D converter of the network. To accomplish this, both the slicing levels and the sampling clock times must be known. This is a hard practical problem and one can only conjecture if a reasonable solution will be possible. The signal may be recovered using a Viterbi detector to reduce intersymbol interference effects, but at present, the number of states required for this detector is very large.< >
DOI:10.1109/ICC.1993.397316