VC-20™ Vocoder Board

Introduction

The Digital Voice Systems, Inc. (DVSI) VC-20™ family of vocoder boards implement DVSI’s proprietary IMBE™ or AMBE® voice compression technology.

The VC-20™ provides full-duplex real-time voice compression complete on one board. This total package design makes it perfect for low risk prototype development and also reduces system integration time. The VC-20™ vocoder board is an ideal low volume manufacturing solution.

The VC-20™ vocoder board digitizes analog speech using an on-board A/D converter. This digitized speech is then encoded by DVSI’s latest voice compression algorithms and converted into a serial data bit stream. This digital data can be output to a modem or similar device.

Simultaneously, the VC-20™ vocoder board receives a data bit stream from the modem or similar device. This received data is processed by the decoder and reconstructed into digitized speech which is then converted into an analog signal using the on-board D/A converter. The encoder and decoder are fully asynchronous.

The VC-20™ vocoder board can also be used in a stand-alone loop-back mode by providing its own channel clock and framing signals. This provides an effective method to evaluate voice quality without connecting across a channel interface.

The board is designed to be configured with different algorithms to operate with one of the following international communications program:

• Inmarsat M
• Inmarsat Mini - M
• OPTUS
• APCO Project 25
• FAA NexCom

Features

• DVSI IMBE™/AMBE® Voice Coder
• Real-Time, Full-Duplex
• Available Data Rates - 2.4kbps to 9.6kbps
• High Quality Analog Interface
• DTMF Tone Processing
• Echo Cancellation
• Watch-Dog Timer
• Self-Test Loop-Back Mode
• Voice Activation/Comfort Noise Insertion
• Soft-Decision Decoding
• Superior Voice Quality
• Robust to Bit Errors & Background Noise
• Low Power
• Compact
• Low Cost
• Uses a Single DSP

Technical Specifications: