CONFIRMATION STEP 1: RECEPTION CONDITION SYMPTOM (EXAMPLE)[RADIO]

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Symptom

Antenna signal condition

Source

Only a buzzing sound from the speakers

•  There is no radio station broadcasting.

•  Signals from the antenna to the audio unit are not transmitted.

•  Electric noise caused by the operation of internal circuit from audio unit itself

•  Atmosphere noise

A buzzing or crunching sound and normal sound produced at the same time from the speakers

•  Though signals are transmitted from the antenna to the audio unit, electrical noise from other sources is larger.

•  Electrical noise caused by the operation of electrical components on the vehicle

•  Electrical noise from high tension wires, transformer substation (factory), electrical feeder line (street car), or motorcycle.

A thumping sound and normal sound produced at the same time from the speakers (FM only)

•  Noise occurs due to radio wave environment at specific places (e.g. in valleys between buildings). Noise varies when the vehicle itself or surrounding vehicles move. (FM only)

•  Interference between direct and reflected waves of FM signals causes noise (Multipass noise).

Symptom	Antenna signal condition	Source
Only a buzzing sound from the speakers	• There is no radio station broadcasting. • Signals from the antenna to the audio unit are not transmitted.	• Electric noise caused by the operation of internal circuit from audio unit itself • Atmosphere noise
A buzzing or crunching sound and normal sound produced at the same time from the speakers	• Though signals are transmitted from the antenna to the audio unit, electrical noise from other sources is larger.	• Electrical noise caused by the operation of electrical components on the vehicle • Electrical noise from high tension wires, transformer substation (factory), electrical feeder line (street car), or motorcycle.
A thumping sound and normal sound produced at the same time from the speakers (FM only)	• Noise occurs due to radio wave environment at specific places (e.g. in valleys between buildings). Noise varies when the vehicle itself or surrounding vehicles move. (FM only)	• Interference between direct and reflected waves of FM signals causes noise (Multipass noise).