AUDIO AND VISUAL SYSTEM SYSTEM DESCRIPTION


  1. RADIO WAVE BAND

    The radio wave bands used in radio broadcasting are as follows:

    A01KF4K

  2. SERVICE AREA

    A01KFZWE01
    Text in Illustration
    *a FM (Stereo)
    *b FM (Monaural)
    *c AM

    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 can be received 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.

  3. RECEPTION PROBLEMS

    Tech Tips

    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.


    1. A01KFQZE01
      Text in Illustration
      *a Fading
      *b Ionosphere

      Fading

      Besides electrical interference, AM broadcasts are also susceptible to other types of interference, especially 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".

    2. A01KFZTE01
      Text in Illustration
      *a Multipath

      Multipath

      One type of interference caused by the bounce of radio waves off of obstructions is called "multipath". Multipath occurs when a signal from the broadcast transmitter antenna bounces off buildings and mountains and interferes with the signal that is received directly.

    3. A01KEWVE01
      Text in Illustration
      *a Fade Out

      Fade Out

      Because FM radio waves are of higher frequencies than AM radio waves, they bounce off buildings, mountains, and other obstructions. For this reason, FM signals often seem to gradually disappear or fade away as the vehicle goes behind a building or other obstruction. This is called "fade out".

  4. NOISE PROBLEMS


    1. Questionnaire for noise:

      It is very important for noise troubleshooting to have good understanding of the claims from the customers, so make the best use of following questionnaire and diagnose the problem accurately.

      Radio wave Noise occurs at a specific place. Strong possibility of foreign noise.

      AM

      (MW)

      SW

      LW

      		 Noise occurs when listening to faint broadcasting. There is a case that the same program is broadcasted from each local station and that may be the case you are listening different station if the program is the same.

      FM

      (UKW)

      		 Noise occurs only at night. Strong possibility of the beat from a distant broadcasting.
      Noise occurs while driving and at a specific place. Strong possibility of multipath noise and fading noise caused by the changes of FM waves.

      Tech Tips

      In the case that the noise occurrence condition does not meet any of the above questionnaire, check based on the "Reception problems".

      Refer to above descriptions for multipath and fading.