Multi-channel PCM signal conversion with channel selection

摘要

A conversion apparatus for converting PCM signals in a system employing two different modulation techniques. In the apparatus, a channel selector (Fig. 3, not shown) generates a channel select signal (SFS) for designating at least one of multiple channels of an input digital signal. A first codec (310) demodulates a signal on a channel designated by the channel select signal, being modulated by a first modulation technique, into an analogue signal to be supplied to a second codec and modulates an analogue signal input from the second codec by the first modulation technique. The second codec (320) demodulates a signal on the channel designated by the channel select signal, being modulated by a second modulation technique, into an analogue signal to be supplied to the first codec and modulates the analogue signal input from the first codec by the second modulation technique. The first and second modulation techniques may be A-law and mu-law. The channel selection facility enables conversion of certain ones only of a multi-channel signal which require conversion.