Audio And Visual System (For Sedan) Identification Of Noise Source

AudioVisualTelematics. Yaris. Ncp93, 131
Audio Video. Yaris. Ncp93, 131

  1. Radio Description

Audio And Visual System (For Sedan) -- Identification Of Noise Source



Radio Description


  1. Radio frequency band



    1. Radio broadcasts use the radio frequency bands shown in the table below.


      Yaris. Ncp93, 131.Audio Video.Audio And Visual System (For Sedan).Audio And Visual System (For Sedan) Identification Of Noise Source



    2. Yaris. Ncp93, 131.Audio Video.Audio And Visual System (For Sedan).Audio And Visual System (For Sedan) Identification Of Noise Source

  2. Service area

    1. The service areas of AM and FM broadcasts are vastly different. Sometimes an AM broadcast can be received very clearly but an FM stereo cannot. FM stereo has the smallest service area, and is prone to pick up static and other types of interference such as noise.

      Text in Illustration
      *a
      		FM (Stereo)
      *b
      		FM (Monaural)
      *c
      		AM


  3. Radio reception problems

    HINT:
    In addition to static, other problems such as "phasing", "multipath", and "fade out" exist. These problems are not caused by electrical noise, but by the radio signal propagation method itself.



      Yaris. Ncp93, 131.Audio Video.Audio And Visual System (For Sedan).Audio And Visual System (For Sedan) Identification Of Noise Source

    1. Phasing
      AM broadcasts are susceptible to electrical interference and another kind of interference called phasing. Occurring only at night, phasing is the interference created when a vehicle receives 2 radio wave signals from the same transmitter. One signal is reflected off the ionosphere and the other signal is received directly from the transmitter.

      Text in Illustration
      *a
      		Phasing
      *b
      		Ionosphere


      2. Yaris. Ncp93, 131.Audio Video.Audio And Visual System (For Sedan).Audio And Visual System (For Sedan) Identification Of Noise Source

    2. Multipath
      Multipath is a type of interference created when a vehicle receives 2 radio wave signals from the same transmitter. One signal is reflected off buildings or mountains and the other signal is received directly from the transmitter.

      Text in Illustration
      *a
      		Multipath


      3. Yaris. Ncp93, 131.Audio Video.Audio And Visual System (For Sedan).Audio And Visual System (For Sedan) Identification Of Noise Source

    3. Fade out
      Fade out is caused by objects (buildings, mountains, and other such large obstacles) that deflect away part of a signal, resulting in a weaker signal when the object is between the transmitter and vehicle. High frequency radio waves, such as FM broadcasts, are easily deflected by obstructions. Low frequency radio waves, such as AM broadcasts, are less likely to deflect.

      Text in Illustration
      *a
      		Fade Out

  4. Noise problem
    Technicians must have a clear understanding about each customer's noise complaint. Use the following table to diagnose noise problems.

    Radio Frequency
    		Noise Occurrence Condition
    		Presumable Cause
    AM
    		Noise occurs in a specified area
    		Foreign noise
    AM
    		Noise occurs when listening to an intermittent broadcast
    		An identical program transmitted from multiple towers can cause noise where the signals overlap
    AM
    		Noise occurs only at night
    		Signal phasing
    FM
    		Noise occurs while driving in a specified area
    		Multipath resulting from a change in FM frequency