SVM - Selector & Vocoder Module

SVM (Selector & Vocoder Module) is the basis for the SVBS, and each SVM contains 15 vocoders. The SVMs are mainly responsible for the conversion between 64kb/s coding and QCELP coding. They are the center of voice data processing in the BSC. They support voice channels in soft handoff by means of multi-channel backward packet service data selecting function. They take part in backward outer-loop power control by means of backward FER statistics and adjustment of backward SNR threshold. Modularized design is employed on the hardware, and state-of-the-art technologies are adopted on the basis of careful analysis and studies. Product upgrading and development potentials, as well as various factors such as thermal design and electromagnetic compatibility design have been taken into consideration from the selection of components to PCB arrangement, so as to ensure the board reliability.

Basic Structure and Functions of SVM

The functions of SVM are briefly described as follows:

Main control unit:

Performs the control of SVE and data interface; implements selector and power control functions; fault detection and reporting;

Data interface unit:

Provides a packet data interface for the communication within the BSS system;

HW interface unit:

 Implements clock conversion and provides code flow data channel for SVE;

SVE:

Implements QCELP conversion, with 15 vocoders;

Clock, power supply and rest circuit:

 Implements clock and board reset of the main control unit, and provides all types of power supplies, including 5V, 3.3V and 2.5V.