Motorola GM Series, Руководство по установке

Страница: 27 / 36

Operation of a Conventional Ignition System 2-3
1.4 Induced Noise
Induced noise enters the radio through the proximity of radio wiring to other wiring in the vehicle.
Electrical currents through the standard vehicular wiring can induce undesirable noise signals into
the radio cabling. Communication is degraded simply because the wiring provides a transformer-
type coupling action without any actual physical connection. Induced noise can degrade both
transmit and receive performance of a mobile radio.
2.0 Operation of a Conventional Ignition System
2.1 Introduction
To effectively reduce ignition interference in a vehicle, it is well to understand the operation of an
automobile ignition system.
Ignition is necessary in a gasoline engine to ignite the gasoline vapor and the air mixture in its
cylinders. The system is made up of the battery, distributor, breaker points, coil, condenser, and
spark plugs. The battery is the only electrical source of power in an automobile, so the lower battery
voltage must be stepped up to the high voltage necessary to arc across the spark plug electrodes.
This arc ignites the gas mixture.
2.2 Sources of Ignition Interference
In the conventional ignition system ( Figure 2-2 Typical Vehicular Ignition System, Simplified
Schematic Diagram) a mechanical circuit breaker (the cam and points in the distributor) opens the
primary circuit of the ignition coil, and high voltage is developed at the secondary. This high voltage
is synchronized and applied to each spark plug by the distributor.