Audio System - Toyota Celica 2005 Repair Manual

BE−90

AUDIO SYSTEM

DESCRIPTION
1. RADIO WAVE BAND
The radio wave bands used in radio broadcasting are as follows:
Frequency
Designation
Radio wave
Modulation method
LF: Low frequency MF: Medium Frequency HF: High Frequency VHF: Very High Frequency
FM (Stereo)
FM (Monaural)
AM
Fading
Ionosphere
2005 CELICA (RM1131U)
BODY ELECTRICAL
30 kHz
300 kHz
LF
Amplitude modulation
2.
There are great differences in the size of the service area for AM
and FM monaural. Sometimes FM stereo broadcasts cannot be
received even through AM comes in very clearly.
Not only does FM stereo have the smallest service area, but it
also picks up static and other types of interference ("noise")
easily.
BE2818
3.
Besides the problem of static, there are also the problems
called "fading", "multipath" and "fade out". These problems are
caused not by electrical noise but by the nature of the radio
waves themselves.
BE2819
− AUDIO SYSTEM
3 MHz
MF
AM
SERVICE AREA
RECEPTION PROBLEMS
Fading
S
Besides electrical interference, AM broadcasts are
also susceptible to other types of interference, es-
pecially at night. This is because AM radio waves
bounce off the ionosphere at night. These radio
waves then interfere with the signals from the same
transmitter that reach the vehicle's antenna directly.
This type of interference is called "fading".
2264
30 MHz
VHF
HF
FM
Frequency modulation
BE2FE−03
300 MHz