Frequency Generating Section (Synthesizer); Digital & Audio Section - Motorola MTP700 Detailed Service Manual

4.1 - 4

Frequency Generating Section (Synthesizer)

The frequency generating section contains the following components:
•
•
•
•
Digital & Audio Section
The digital section includes the RedCap2 host micro-processor which is the controller of
the Digital/RF Board. It controls the operation of the audio and transmitter, receiver, and
synthesizer integrated circuits located in the RF section. It has the serial communication
interface to communicate with the keypad, display and other internal peripherals.
For audio, the RedCap2 contains a Digital Signal Processor (DSP) which performs mod-
ulation and de-modulation functions for the radio. It also performs ACELP speech coding
and Forward Error Correction.
Major components of the digital section are:
•
•
•
•
•
•
•
MTP700 Portable Radio / Detailed Service Manual
TCXO Reference Oscillator.
Main Synthesizer - consists of the WPIC's PLL and the Main Voltage Controlled
Oscillator (VCO).
2nd Local Oscillator (LO) VCO together with the LMX Dual Synthesizer IC.
Transmit PLL - consists of TX VCO together with ESCORT Synthesizer IC.
RedCap2 (microprocessor with DSP embedded)
GCAP3 (DC power supply and audio amplifier circuits)
Serial peripheral interface (SPI)
External host memories (Flash and SRAM)
Keypad block & circuits
LCD (liquid-crystal display) circuits
Bottom connector & side connector interface circuits
TRANSCEIVER 400 MHz