Digital Voice Systems AMBE-20X0 HDK, Руководство пользователя

Страница: 13 / 45

AMBE-20x0™-HDK Development Board
User’s Manual
(Preliminary)
Page 5
DVSI Confidential Proprietary
Section 1 – Introduction
Voice Activation Detection (VAD)
The Voice Activation Detection (VAD) algorithm along with the Comfort Noise Insertion (CNI) feature of
the AMBE-2000™ chip performs useful functions in systems trying to convert periods of silence, that
exist in normal conversation, to savings in system bandwidth or power. . For more information
regarding the VAD, refer to the AMBE-2000 User’s Manual.
Comfort Noise Insertion (CNI)
The synthesis of a Comfort Noise frame by the decoder is not dependant on VAD being enabled. The
decoder will produce a comfort noise frame if it receives an in-band silence frame (produced only by an
encoder with VAD enabled). . For more information regarding the CNI, refer to the AMBE-2000 User’s
Manual.
Echo Cancellation
The AMBE-2000™ Vocoder Chip employs an adaptive echo cancellation algorithm to cancel echoes of
the decoder output present at the encoder input. . Only the linear portion of the echo is cancelled, so
circuits should be designed to minimize non-linearity’s. For more information regarding the Echo
canceller, refer to the AMBE-2000 User’s Manual included on the AMBE-20x0™ HDK software CD.
What’s Included with the HDK
The AMBE-20x0™ HDK is a complete package solution. The development kit includes the following
items
HDK evaluation board
Power Adapter (120v AC to 5 V DC)
Handset with cord
Documentation CD
The documentation CD contains the AMBE-2000™ User’s Manual, program code for the on board
microprocessor (MSP430) (see Note) and the XILINX Programmable Logic Device and a program
executable for interfacing with a PC, as well as a full set of schematics and reference circuit designs.
Note: The development tools for the MSP430 MCU are widely available and easily obtained from Texas
Instruments and various sources on the web. This gives designers an opportunity to recompile the code
to test other configurations. The main tool tree is a port of the GNU GCC for the MSP430. This allows for
a robust development environment free of cost.