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•+12V | Any power source which inevitably
is connected to the positive terminal of the battery as opposed
to "ground" which is connected to the negative terminal. |
|
•Accessory | Referred to as the power supply
that is available when the key is in "accessory" or "on" position.
This connection will lose power during engine cranking. |
|
•Audio Mute | A feature that is enabled by a common
connection between two devices allowing a signal to be made
to the audio output device to briefly mute it's output. This
is used when products such as navigation devices need to advise
the driver of an instruction. An "audio mute" feature supported
by the headunit or other device in the audio system can mute
the audio briefly so the verbal instruction emitted by the
navigation device can be heard. |
|
•Band Pass | In a crossover, any pass band output
which has filtering at both a lower and an upper limit. A
midrange output is a good example where low frequencies and
high frequencies are filtered. |
| •Bus Translators | Devices that convert one type of communication protocol to another to allow interplay of unrelated devices. For example, a translator may be used to allow a factory headunit normally intended to operate a factory CD Changer to instead be able to operate and play an aftermarket satellite radio receiver. Some models will even allow Artist Name and Song Title to appear on the factory radio screens if they are equipped to display text. This allows for an easy customer interface to the satellite radio device without adding additional controls or displays to the dashboard.
|
|
•Crossover | A device that separates a broad
spectrum of sound into individual groups of frequencies or
"pass bands", for better clarity and so as not to damage task-specific
speakers. A three-way crossover, for instance would typically
separate lows, midrange and high frequencies. A "passive"
crossover operates with no external power. These are found
on speaker level connections following amplification and would
separate the audio outputs for a woofer, a midrange and a
tweeter. An "active" crossover is an electronic device, powered
by the electrical system (in this case a car battery) and
is usually a pre-amp device meaning that it divides the frequencies
prior to amplification. Separate outputs from an active crossover
are sent to individual amplifiers. |
|
•DIN | (Deutsche Industry Norm) A set of
industry standards originally devised in Europe for defining
sizes, shapes and connector types among many electrical items.
DIN is most commonly referred to in mobile electronics as
a headunit size. A "single DIN" sized headunit has a face
approximately 2-inches tall by 7-inches wide. Ford as well
as European and Japanese vehicles are the most common users
of these sizes for factory-installed headunits. "Double-DIN"
is commonly used with many Japanese carmakers as well as newer
GM vehicles. |
|
•Distribution Block | A device for dividing larger power
and ground cables into smaller individually fused lines for
multiple sources. |
|
•DMM | (Digital Multi-Meter) A multi-function
device used for testing voltage, amperage and resistance with
a digital display. |
|
•EIA Color Codes |
(Electronic Industry Association) Color Codes are universal
codes developed to standardize aftermarket wire colors for
various common wire functions:
RED (+12V) Ignition/Accessory
power. On when ignition is on or in accessory.
YELLOW (+12V) Memory. Always
on even with ignition off. Keeps clock/radio memory.
BLACK Ground (-)
BLUE (+12V) Power Antenna.
Antenna rises when radio is turned on. Also may be used
for amp remote turn-on if there is not an extra wire for
remote turn-on.
BLUE/WHITE (+12V) Power Amp
turn-on. If there is no wire for remote turn-on, use power
antenna lead.
ORANGE (+12V) Illumination.
ORANGE/WHITE Dimmer.
GREY (+) Right Front Speaker.
GREY/BLACK (-) Right Front
Speaker.
WHITE (+) Left Front Speaker.
WHITE/BLACK (-) Left Front Speaker.
PURPLE (+) Right Rear Speaker.
PURPLE/BLACK (-) Right Rear
Speaker.
GREEN (+) Left Rear Speaker.
GREEN/BLACK (-) Left Rear Speaker. |
|
•Engine Noise | Typically the noise described as
a "whining" tone audible in the speakers of the sound system
that rises in pitch with increased engine RPM. This is typically
the result of a poor ground in one of the system components
resulting in a "ground loop". |
|
•FM Modulator | A device that converts an audio signal into a FM carrier signal and modulates it to a specific frequency so that standard FM tuners can tune into the broadcast. Connected through the vehicle antenna system, it is a closed system and operates only on the headunit it is connected to. Commonly used to add CD changers and other audio devices to existing OEM factory audio systems. The only requirement is a working FM tuner and the necessary hardware to integrate into the antenna cabling.
|
| •FM Transmitter | A device that converts an audio signal into a FM carrier signal and modulates it to a specific frequency so that standard FM tuners can tune into the broadcast. As a transmitter though, this device has the ability to transmit the signal wirelessly to nearby FM receivers. The FCC limits the amount of output power so the range is confined to within a vehicle. It is popular for adding devices easily and without installation concerns to existing OEM factory audio systems. The only requirement is a working FM tuner and a free FM frequency not being used in the immediate area.
|
|
•Ground | In vehicles, "ground" is anything
with an electrical connection to the negative terminal of
the battery. This is not only wiring but it includes the entire
metal chassis of the car and anything connected to it that
is electrically conductive. |
|
•Ground Loop | A common problem in vehicles in
which multiple components which are interconnected via cables
and derive their "ground" connections for power at different
points in the car. The interconnect cables which attempt to
simply use ground to shield the sensitive low current audio
signals end up transferring power to the poorer grounded component,
thus inducing noise into the system via radiation. |
|
•Ground Loop Isolator | When no alternative correction can
be found, this device can sometimes isolate and eliminate
"ground loops" between components using transformers to decouple
the ground connection between them without eliminating the
ground shield aspect. |
|
•Ground Plane | An electrically conductive surface
that serves as the near-field reflection point for an antenna.
A ground plane may consist of a natural (e.g., Earth or sea)
surface or an artificial surface such as the roof of a motor
vehicle. |
|
•Headunit | In vehicles, this is the common
term for the source unit which is the system master control.
Headunits typically include the AM/FM tuner, a cassette or
CD player, volume controls as well as tone, balance and fader
controls. |
|
•High Pass | An output of a crossover that has
filtering for low frequencies to prevent them from either
damaging an upper frequency speaker or from being audible
when not desired. |
|
•Ignition | Referred to as power wires which
are only "hot" when the key is in the "ignition" position. |
|
•ISO Mount | (International Standards Organization)
mount means that the product has been designed to conform
to standard mounting holes in the sides that line up with
participating automotive suppliers for easy installation.
Most Japanese car companies observe this standard allowing
installation of aftermarket products to use the same mounting
hardware as the original equipment. It also usually means
that the cosmetic trim ring for the aftermarket headunit is
removable allowing the factory trim ring or bezel to serve
as the cosmetic finish. ISO standards evolved from the development
of the DIN initiatives. |
|
•Line Level | Common inter-connect electrical
current used to send pre-amplified audio signals from one
component to another. This is the current seen in RCA cables
as well as other component interconnect audio cables. While
typically fixed at 500mV and a high impedance of 10K ohms
in home applications, for vehicles it can range from 200mV
up to 8V and have impedances anywhere from 4ohms up to 10K
or more. Higher voltages are considered premium as they have
been developed to counter the many noise producing elements
in vehicles. For this reason, most amplifiers have variable
input buffers to correctly match them to the appropriate voltage
level. |
|
•Low Pass | An output of a crossover that has
filtering for high frequencies to prevent them from being
audible when not desired. |
|
•MECP | (Mobile Electronics Certified Professionals)
A program developed and maintained by the Consumer Electronics
Association to educate, train and certify mobile electronics
installers and salespeople in the advanced theory and applied
principles of today's electronic and automotive industry products.
|
|
•Noise Suppressor | A device designed to attempt to
reduce the amount of noise audible in an audio system. Usually,
with good installation practices, these devices are unnecessary. |
|
•OEM | (Original Equipment Manufacturer)
A manufacturer who produces products which are installed at
the automobile factory. |
| •Plug and Play Receiver | A term used for a portable Satellite Radio device that can easily be removed and docked in additional locations for listening such as homes, offices, boats, etc. Consisting of a main unit and multiple cradles. The cradles tailor the device to the desired environment handling all of the connections necessary to integrate into home or mobile audio systems and using the appropriate antennas.
|
|
•Radiated Noise | Noise that enters an audio component
through radiated means. A common occurrence for this is where
audio patch cables run alongside high current power wires.
The proximity of the wires allows the electrical field around
the power wire to enter the pathway of the audio wire and
ride along it to the connected components, often audible as
engine noise or buzzing coming from the speakers. |
|
•Relay | An electromagnetic device used for
a multitude of functions including switching large amounts
of current, reversing polarity in electrical systems or acting
as simple triggers when signaled to do so. |
|
•Remote Turn-On | A trigger used to signal components
mounted in out of reach locations to power themselves on.
This is typically a +12V connection and is activated by a
headunit or some other master control device. A good example
is a power antenna, which is signaled through a remote turn-on
wire from the headunit when it is powered on. |
|
•Speaker Level | This is a reference to the electrical
current present on the outputs of amplifiers connected to
speakers. It is not fixed and varies with the size of the
amplifier. The amplifier may be external or internal such
as in a headunit that can be connected directly to speakers.
The importance of this is for adding greater amplification
to existing OEM headunits which are not equipped with the
typical RCA outputs most amplifiers require. Many aftermarket
amplifiers have "speaker level" inputs along with the RCA
inputs allowing them to be easily incorporated into OEM systems.
Additionally, many companies also offer adaptors that will
convert the higher speaker level outputs down to RCA line
level so amplifiers without speaker level inputs can be used.
|
|
•Test Light | A simple handheld probe which uses
a 12 volt bulb that lights when it's two conductors are connected
to +12 volts and ground. It typically is characterized by
a sharply pointed handheld probe containing the bulb with
a 2-3-foot cord ending in an alligator clip. Test lights used
to be a common method for testing for the presence of voltage
and polarity on wires in the past but should be avoided as
a probe now as they can easily damage expensive microprocessors
prevalent in modern automobiles. A DMM (Digital Multi-Meter)
is a much better choice |
| •VOM | (Volt-Ohm Meter) An analog device
used to test and measure voltage and resistance. Some models
also feature current measurement capability as well. |
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