CODER AND DECODER

PURPOSE:To decrease the scale of the hardware by using the common a filter, an analog-digital converter and a digital-analog converter depending on the broad band coding and the pulse code modulation coding. CONSTITUTION:When the titled coder/decoder acts like a coder, a switch 17 is thrown to a terminal 28 and a switch 19 is thrown to a terminal 29 by a switching control signal B of the PCM coding rule, a signal passing through a pre- filter 15, the analog-digital converter 16 and a band pass filter 21 is inputted to a linear pulse code modulating code-nonlinear pulse code modulation code converter and its output is outputted to a digital output terminal 10. In acting the coder/encoder like a decoder, a switch 31 is thrown to a terminal 44 and a switch 33 is thrown to a terminal 45, a pulse code modulation code inputted from a terminal 11 is inputted to a nonlinear pulse code modulation code-linear pulse code converter 46, its output is inputted to a band pass filter 39, from which an output is given through a digital-analog converter 42 and a post-filter 43.