Digital Voice Systems VC-20 User manual

The VC-20™ family of vocoder boards offer a
variety of software algorithms. The VC-20™ can
be configured to inter-operate with one of the
following international communication systems.
·Imarsat M
·Imarsat Mini-M
·OPTUS
·APCO Project 25
·FAA NexCom
Each VC-20™ Vocoder board delivers excellent
voice quality that is robust to bit errors and
background noise. The low power,compactboard
design also features:
·Real-Time, Full-Duplex Voice processing
·Analog and Digital Interface
·DTMF Tone Processing
·Echo Cancellation
·Self-Test Loop-Back Mode
·Voice Activation/Comfort Noise Insertion
·Soft-Decision Decoding
The Speech Compression Specialists
Digital Voice Systems, Inc.
Westford, MA 01886
Web site: www.dvsinc.com
Digital Voice Systems, Inc.
Tel: [phone]
234 Littleton Road
Fax: [phone]
VC-20™ Vocoder Board
The Digital Voice Systems, Inc. (DVSI) VC-20™ vocoder board is the
ideal platform for testing, evaluating and implementing DVSI’s voice
compression technology. The VC-20™ Vocoder Board is a full-duplex
real-time voice compression solution that is perfect for low risk
prototype development and small volume manufacturing. The VC-
20™’s single board design also reduces system integration time.
The VC-20™ can be equipped with one of DVSI’s standard-setting
voice compression implementations. These patented software
algorithms have been proven in numerous evaluations to out perform
CELP and other competitive technologies. DVSI’s voice compression
software is used in applications throughout the world, including
satellite applications and the next generation of digital mobile
communication systems.
TheVC-20™ vocoder board uses an on-board A/D converter todigitize
the analog speech input. The digitized speech is then encoded by
the DVSI voice compression algorithm and converted into a serial
data bit stream. This digital data is then available for output to a
modem or similar device.
Simultaneously, the VC-20™ vocoder board receives a data bit stream
from the modem or similar device. The data received is processed
by the decoder, reconstructed into digitized speech and then
converted into an analog signal using an on-board D/A converter.
The encoder and decoder are fully asynchronous.
Connecting two boards together allows for simulation, testing and
operation across various channel conditions. The VC-20™ vocoder
board can also be used in a stand-alone loop-back mode by providing
itsownchannelclockandframingsignals. Thisisaneffectivemethod
to evaluate voice quality without connecting to a channel interface.
The VC-20™ offers a number of advanced features, including
automatic Voice/Silence detection (VAD), adaptive comfort noise
generation, DTMF detection and signaling, and echo cancellation.
These features are designed into the entire line of VC-20™ boards,
insuring that each vocoder board delivers superior voice quality at
a low data rate. With outstanding robustness to both acoustic
background noise and limited channel errors, the VC-20™ delivers
optimum voice comprehension even under extreme conditions.
DVSI’s dedicated staff combine years of experience in vocoder
technology, with expertise in Digital Signal Processing, computer
software generation and hardware development. For more
information regarding our high-quality low-data-rate voice
compression, contact DVSI today.
IMBE is a trademark of Digital Voice Systems, Inc., AMBE is a registered trademark of Digital Voice Systems, Inc., © Copyright Digital Voice Systems, Inc. 2003 All Rights Reserved.
Analog Input/Output:
Type Single-ended
Input Impedance 600 ohm
Output Impedance low, drives 600 ohm load
Sensitivity 0 dBm0 = 0 dBm
Sinusoidal Overload +3.17 dBm0
Nominal Level -23 dBm0
Dynamic Range +/- 10 dB
Noise Level -72 dBm0
Bandwidth (Output) 20 – 3700 Hz.
Digital Interface: TTL compatible
Power Requirements: 2.0 W @ 5V digital
0.2 W @ +/- 5V analog
Physical Size: 4.75” x 4.0” (3U height)
Male Connector: DIN 41612 (96-pin)
Specifications subject to change.
Technical Specifications