Modern vehicles integrate audio, video and communication systems into a network. This allows for a high quality, compact and ergonomic system, which combines entertainment features with simple operation.
Controls are centralized with hardware, such as CD stackers, and DVD players located remotely.
Communication between components uses a combination of hard wiring and data buses.
With data buses being used, audio messages can be broadcast over the audio system that relate to other vehicle systems. For example, a voice message can say “the park brake is on” or “left rear tire is under inflated”
The system allows for features such as the interruption or replacement of audio entertainment when there is an incoming phone call, or simply muting the audio to allow a hands-free phone conversation.
Audio control functions are usually located on the central control pod or on the component’s head unit. Vehicles can integrate the common audio controls on the steering wheel to allow for safer driving.
The music played on a system usually comes from one of several sources. Magnetically on a cassette tape, optically on a CD or DVD, by radio frequency from radio stations or satellites, or from other portable devices.
The information is decoded or processed by the control unit and outputted to drive speakers located throughout the vehicle.
Another function provided by the body control unit is that of speed dependant volume. The control unit has an input from the vehicle speed sensor, which allows it to gradually increase audio system volume proportionally with road speed. As speed, and therefore engine and road noise increases, the audio volume will increase. As speed decreases the audio volume will decrease.
Viewing screens for onboard TV, DVD and games can be located in the dash, however, if the screen is viewable by the driver it must disable when the vehicle is in motion. Other mounting points are from the roof or integrated into the rear of seat headrests.
Control units can be hard wired, or wireless using an infrared remote control.