Audio System: Description

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

Fig 1: Identifying Radio Band Frequencies & Types

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

LF: Low frequency MF: Medium Frequency HF: High Frequency VHF: Very High Frequency

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.

Fig 2: Identifying Frequency Service Ranges

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. 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".

   Fig 3: Identifying Cause Of Fading

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Multipath

   One type of interference caused by the bouncing 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.

   Fig 4: Identifying Cause Of Multipathing

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. 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".

   Fig 5: Identifying Cause Of Fade Out

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Raise the cassette door with your finger.
2. Next, using a pencil or like object, push in the guide.
3. Using a cleaning pen or cotton applicator soaked in cleaner, clean the head surface, pinch rollers and capstans.
   Fig 6: Locating Head, Pinch Rollers & Capstans

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. What is AVC-LAN?

   AVC-LAN is the abbreviation, which stands for Audio Visual Communication-Local Area Network.

   This is a unified standard co-developed by 6 audio manufactures associated with Toyota Motor Corporation.

   The Unified standard covers signals, such as audio signal, visual signal, signal for switch indication and communication signal.

2. Objectives

   Recently the car audio system has been rapidly developed and functions have been changed drastically. The conventional system has been switched to the multi-media type such as a navigation system. At the same time the level of customers needs to audio system has been heightened. This lies behind this standardization.

   The concrete objectives are explained below.

   • When products by different manufacturers were combined together, there used to be a case that malfunction occurred such as sound did not come out. This problem has been resolved by standardization of signals.
   • Various types of after market products have been able to add or replace freely.
   • Thanks to the above (2), each manufacturer has become able to concentrate on developing products in their strongest field. This has enabled many types of products provided inexpensively.
   • Conventionally, a new product developed by a manufacturer could not be used due to a lack of compatibility with other manufacturers products. Thanks to this new standard, users can enjoy compatible products provided for them timely.

     The above descriptions are the objectives to introduce AVC-LAN. By this standardization, development of new products will no longer cause systematic errors. Thus, this is a very effective standard for a product in the future.