Motorola Commercial Series Informations sur les services - Page 9

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Également pour Motorola Commercial Series : Manuel d'utilisation de base (16 pages), Informations sur les services (46 pages), Manuel de l'utilisateur (18 pages), Manuel d'utilisation de base (12 pages), Informations sur les services (30 pages)

1.0

This Chapter provides a detailed theory of operation for the VHF circuits in the radio. Schematic

diagrams and board layout diagrams are included in Chapter 4 in this Section of the manual.

2.0

The VHF receiver covers the range of 136-162 MHz and provides switchable IF bandwidth for use

with 20/25/30 kHz or 12.5 kHz channel spacing systems. The receiver is divided into two major

blocks, as shown in Figure 2-1.

■

Front End

■

Back End

RX from

Antenna Switch

Preselector

Filter

Amp

First LO

from Synthesizer

Recovered Audio

RSSI

Figure 2-1 VHF Receiver Block Diagram

THEORY OF OPERATION

Interstage

Crystal

Filter

1st Mixer

Inj Filter

Ceramic

Resonator

Demodulator

12.5kHzFilter

Chapter 2

Amp

Filter

BW_SEL

Cer Fltr

Switching