Integrated PCM Codec
KUL B. OHRI AND MICHAEL J.CALLAHAN, JR., MEMBER,lEEE
Abstract
one-chip
PCM
codec
circuit
has
been
implemented
the
CMOS
process.
The
design uses two separate linear digital-to-analog converters, made with charge
redistribution techniques.
Experimental results show tbe circuit to meet accepted requirements
and operate with very low power requirements.
SINGLE-CHIP CMOS PCM CODEC
THE processing of voice signals in a digital manner is becoming more popular. There
are several contending modulation schemes including pulse-width modulation
(PWM),pulse-amplitude modulation (PAM), delta modulation, and pulse-code modulation
(PCM).
A specific PCM approach [1] has become the standard in
North America. There are two separate types of applications
for this time-division multiplex scheme: transmission and
digital voice switching. Transmission involves sending the
voice data in digital form from one location to another. Since
the transmit and receive circuitry are separated from one
another, some sort of synchronization is implied in this
scheme. Applications of this type are concentrators and channel
banks.
Switching involves only the connection of one voice channel
to another in a digital mamner. This scheme has the transmit
and receive circuitry in close proximity so that clocking and
synchronization may be done by one common circuit. Important
applications of this type are electronic PABX and digital
central offices.
In the system defined by [1], the analog input signal is
sampled at an 8 kHz rate. Fig. 1 shows a 1 kHz input sampled
in this manner. At each of these sampling times, the analog
information is converted into an 8-bit digital word that is
transmitted in serial format at a 1.544 Mbit/s rate.
Fig. 2 shows twenty-four voice channels which are timedivision
multiplexed onto one pair of wires. (For simplicity,
only simplex operation is shown.) Each channel is first bandlimited
to less than 4 kHz by the XMIT tilter, then sampled
and converted to a companded digital code. The 8-bit words
are transmitted serially to a multiplexer.The bit stream of
1.544 Mbits/s is sent to a demultiplexer where the appropriate
A~(lZ=l, 2,
24) channel is connected to the BM(rrz = 1,
24) channel. This selection is done by the main computer,
Original: https://blog.csdn.net/weixin_42502165/article/details/112996226
Author: 有人叫我黑花
Title: a律13折线pcm编码例题_基于MATLAB语音信号的A律13折线PCM编解码的设计与分析
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