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).

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