A head unit, sometimes referred to as a "deck", is a component of a stereo system either in a vehicle

Vehicle

A vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....

 or home cinema system which provides a unified hardware interface for the various components of an electronic media system. An antiquated name for a head unit is a receiver

Receiver (radio)

A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...

; this article focuses on vehicular applications.

The head unit is the centerpiece of the car's sound system. Typically located in the center of the dashboard

Dashboard

A dashboard is a control panel placed in front of the driver of an automobile, housing instrumentation and controls for operation of the vehicle....

, modern head units are densely integrated electronic packages housed in detachable face plates. As high-end head units are common targets for theft, many head units are typically integrated into the vehicle's alarm system.

Head units give the user control over the vehicle's entertainment media: AM/FM radio, satellite radio

Satellite radio

Satellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...

, CDs, cassette tapes (although these are now uncommon), MP3

MP3

MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...

, GPS navigation, Bluetooth

Bluetooth

Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...

, etc. Many audio-only head units afford the user precise control over detailed audio functions such as volume, band, frequency, speaker balance, speaker fade, bass, treble, EQ

Equalization

Equalization, is the process of adjusting the balance between frequency components within an electronic signal. The most well known use of equalization is in sound recording and reproduction but there are many other applications in electronics and telecommunications. The circuit or equipment used...

 and so on.

Several OEM

OEM

OEM means the original manufacturer of a component for a product, which may be resold by another company.OEM may also refer to:-Computing:* OEM font, or OEM-US, the original character set of the IBM PC, circa 1981...

s such as General Motors are integrating more advanced systems into vehicle's head units such that they can control vehicular functions such as door chimes and even offer vehicle data such as trouble warnings and odometer information; such a head unit thus serves as a secondary instrument panel.

In as much as head units are a central part of a car's decor, they vary as widely in aesthetics as they do in functionality; in this regard they are analogous to skin

Skin (computing)

In computing, a skin is a custom graphical appearance achieved by the use of a graphical user interface that can be applied to specific software and websites to suit the purpose, topic, or tastes of different users....

s.

With the advent of GPS and DVD

DVD

A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

s head units with video monitors have come on the market. Such features raise design, safety, and ergonomic issues.

The most standard sizes in vehicles are Single DIN ISO 7736

ISO 7736

International standard ISO 7736 defines a standard size for car audio head units. The standard was originally established by the German standards body Deutsches Institut für Normung as DIN 75490, and is therefore commonly referred to as the "DIN car radio size"...

 (178x53 mm) in Europe, South America and Australasia and Double DIN

ISO 7736

International standard ISO 7736 defines a standard size for car audio head units. The standard was originally established by the German standards body Deutsches Institut für Normung as DIN 75490, and is therefore commonly referred to as the "DIN car radio size"...

(178x106 mm) in Japan, the UK and North America.

External links

• MPT 1362 UK code of practice for the installation of mobile radio and ancillary equipment in land based vehicles. Federation of Communications Services Industry, November 2005.