描述 Description

The Dual-channel ADPCM transcoder is a low power, CMOS device capable of two encoder functions and two decoder functions. Two 64 kbit/s PCM channels are compressed into two 32 kbit/s ADPCM channels, and two 32 kbit/s ADPCM channels are expanded into two 64 kbit/s PCM channels. The 32 kbit/s ADPCM transcoding algorithm utilized conforms to CCITT Recommendation G.721 and ANSI T1.303-1989. The device also supports a 24 kbit/s (three bit word) algorithm (CCITT/G.723).

特性 Features

? Dual channel full duplex transcoder

? 32 kbit/s and 24 kbit/s ADPCM coding,

? compatible to G.721 & and G.723 (1988) and ANSI T1.303-1989

? Low power operation, total 25mW typical

? Asynchronous 4.096 MHz master clock operation

? Transparent ADPCM bypass capability

? Serial interface for both PCM and ADPCM data streams

? ST-BUS interface supported

? Pin selected μ-law or A-law operation

? Pin selected CCITT or sign-magnitude PCM coding

? Single 5 volt power supply

? Optional reset value (CCITT Table 3/G.721) capability

Applications

? Pair gain

? Voice mail systems

? Wireless set base stations