Motorola MTP810 EX, Базовое руководство по обслуживанию

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3 - 2 OVERVIEW
Voice Compression Technology
Voice is converted into a digital bit stream by sampling the voice at high rate and
converting the samples into numbers, which are represented by bits.
Voice compression reduces the number of bits per second while maintaining the
voice at an acceptable quality level. The MTP810 Ex uses a coding technique
called ACELP (Algebraic Code Excited Linear Prediction). The compressed
voice-data bits modulate the RF signal.
Description
Transceiver Description
All the radio circuitry is contained in the Digital/RF Board and the keypad board.
The Digital/RF board is divided into the following sections: digital, frequency
generating, transmitter, and receiver.
Digital Section Description
The digital section includes the Patriot IC that consists of the Mcore risk machine
and the Digital Signal Processor (DSP).
The Mcore is the controller of the Digital/RF Board. It controls the operation of the
transmitter, receiver, audio, and synthesizer integrated circuits located in the RF
section. It communicates with the keypad and display.
The Digital Signal Processor (DSP) performs modulation and de-modulation
functions for the radio. It also performs Forward Error Correction and other
correction algorithms for overcoming channel errors and ACELP speech coding.
It carries out linear 16-bit analog to digital conversions, audio filtering, and level
amplification for the microphone audio input and the received audio output.
The power and audio section is based on the PCAP and includes power supplies,
13-bit CODEC, audio routing, microphone and earpiece amplifiers. PCAP audio
power amplifier is used for the loudspeaker.
Transmitter Path Description
The transmitter circuitry includes a linear class AB Power Amplifier (PA) for the
linear modulation of the MTP810 Ex. It includes a Cartesian Loop to enhance its
transmitter linearity and reduced splattering power into adjacent channels.