User`s manual

AMBE-2000™ Vocoder Chip
User’s Manual Version 4.9
DVSI Confidential Proprietary, Subject to Change Page 6
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1. Product Introduction
1.1 General Information
Digital Voice Systems Inc.’s AMBE-2000™ Vocoder Chip is an extremely flexible, high-performance, single chip, speech
compression coder. It provides superior voice quality at low data rates. It provides a real-time, full-duplex implementation of
the standard-setting AMBE

voice compression software algorithm. DVSI’s patented AMBE

voice compression technology
has been proven to outperform CELP, RELP, VSELP, MELP, ECELP, MP-MLQ, LPC-10, and other competitive
technologies. Numerous evaluations have shown its ability to provide performance equal to today’s digital cellular systems at
under half the data rate. The AMBE

voice compression algorithm is used in applications throughout the world, including the
next generation of digital mobile communication systems.
The AMBE-2000™ Vocoder chip provides a high degree of flexibility in selecting the speech and FEC (Forward Error
Correction) data rates. The user can separately select these parameters in 50 bps increments for total rates from 2.0 kbps to 9.6
kbps. Typically for higher error rate channels, the user will apportion a greater percentage of the total bit rate to FEC coding.
The AMBE-2000™ voice coder maintains natural voice quality and speech intelligibility at rates as low as 2.0 kbits/sec. The
AMBE

algorithm’s low complexity allows it to be fully integrated into a low cost, low power integrated circuit, the AMBE-
2000™ Vocoder Chip.
The AMBE-2000™ Vocoder Chip offers similar features to DVSI’s AMBE-1000™ Vocoder Chip allowing it to be
incorporated into systems already designed for the AMBE-1000™ and is interoperable with other DVSI products. The
AMBE-2000™ Vocoder Chip delivers improved performance and enhanced modes such as 4.0 kbps toll quality speech and
convolutional FEC coding. Along with these enhancements the AMBE-2000™ Vocoder Chip employs a control interface
along with the variable data rates and FEC selection.
1.2 Advantages
• Superior Voice Quality
• Low Cost
• No External Memory Required
• Robust to Bit Errors & Background Noise
• Variable Data Rates - 2.0 kbps to 9.6 kbps
• Variable FEC Rates - 50 bps to 7.2 kbps
• Very Low Power (65mW @ 3.3V, 0.11mW Deep Sleep)
• Compact Single Chip Solution: 100 pin TQFP
Features
• High Quality Low Data Rate Speech Coding
• DVSI’s Full Duplex AMBE Voice Coder
• Supports Data Rates of 2.0 kbps to 9.6 kbps in 50 bps increments
• User Selectable Forward Error Correction rates
• Viterbi Decoder (rate 1/4 or more)
• 16 Level Soft Decision Decoding
• Voice Activity Detection (VAD) / Comfort Noise Insertion
• 16 ms Echo Cancellation
• Single and Dual Tone (DTMF) Detection and Generation
• Power-Down Mode
• Minimal algorithmic processing delay