Kirisun TM840 - Product Features and Operation; Control Panel Overview

TM840 Service Manual
Figure 0-3 IF Processing Circuit
3.1.3 Frequency Generation Unit(FGU)
Figure 3.5 Frequency Generation Unit Diagram
Frequency generation unit(FGU) is composed of VCO and PLL. It is the core module of the TX-RX system. When
transmitting, it provides accurate carrier frequency, while receiving, it provides stable local oscillator signal. It has direct
influence on system performance.
（1）Working Principle of PLL
Benchmark crystal generates a 12.8MHz frequency, then it goes into frequency divider of the PLL chip to create a reference
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