OBD - Refer to On Board Diagnostics
OBD-II - Refer to Second Generation On Board Diagnostics
Object Exchange Profile (OBEX) - This is a profile, also known as Infra-red OBEX (IrOBEX), that facilitates the exchange of files between devices. Which allows Bluetooth exchange of what is typically Infra-red exchangeable content (such as contacts or calendar entries on a PDA type device).
Object Push Profile (OPP) - This profile must be "pushed" via Bluetooth to transfer content (such as address books, pictures, or other stored information) into other Bluetooth devices. The exchange must be initiated and accepted by the users, it is not just automatic whenever two Bluetooth devices are within range of one another.
Occupational Safety and Health Act (OSHA) - The United States governmental agency that establishes and enforces safety standards in the workplace.
Octave - A measured musical interval between two tones when the ratio between the frequencies of the tone is 2:1 (double or half of the other) “Oct” is a prefix meaning “eight”. In music, there are 8 steps, tones, or “notes” within an octave. For notes spaced an octave apart, human ear hears them as being essentially the same. That’s why, in music, notes spaced an octave apart have the same name; “A”, “B”, “C”, etc.
OE – Refer to Original Equipment
OEM - Refer to Original Equipment Manufacturer
OFC - Refer to Oxygen Free Copper
Off Axis - Veering away from the imaginary line (axis) directly in front of the receiving end of a microphone. Measured as degrees of an angle. (For example, a sound coming from directly behind the microphone is said to be 180 degrees off-axis.)
Ohm (W) - The unit of electric resistance and impedance. One ohm is the resistance value through which one volt will maintain a current of one ampere.
Ohm’s Law - Current in a circuit is directly proportional to the voltage, and inversely proportional to resistance. It also includes the relationships of watts to amps, volts and ohms.
Open Circuit - A circuit containing a switch, filament, voice coil, etc., which is not intact and current cannot current flow through.
Optical Input - A digital output that transmits pulses of light through an optically conductive cable from a compatible Optical Output
Optical Output - A digital output that transmits pulses of light through an optically conductive cable from a compatible Optical Input.
On Board Diagnostics (OBD) - Is an automotive term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle subsystems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. Also refer to OBD-II.
Order - Used to describe the quality, nature, or importance of something. In audio order is used to refer to the point of a crossover filter or the type of a subwoofer enclosure. In mathematics order is the degree of complexity of an equation, expression, etc., as denoted by an ordinal number. In distribution order is a request (something) to be made, supplied, or served.
Organic Vapor (OV) - Harmful vapors for inhalation. Typically filtered with charcoal respirator cartridges in an OSHA approved respirator mask.
Oscillator - A device that produces an alternating current or pulsating current or voltage electronically.
Oscilloscope - A measurement tool that can display a signal waveform while simultaneous measuring the featuring the frequency and voltage of the signal. Among other uses, this tool is very useful in setting up the gain position on amplifiers to avoid prematurely clipping the waveform coming out of the amplifier.
OSHA - Refer to Occupational Safety and Health Act
Out of Phase - Being or happening in (or out of) synchrony or harmony. In audio this refers to the wave of a speaker or subwoofer. The wave travel of the speaker is not in phase which can cause cancellation of other speakers. This can also mean that a speaker or subwoofers polarity is reversed, placing the speaker out of phase.
Output - In audio the high-level (speaker) or line-level (RCA) signals sent from one system component to another, or the high-level signal from an amplifier to the system speakers. In security any wire on a security system designed to produce a signal intended to be wired to some outside circuit or device. Siren wires, flashing light wires, and door locks are all outputs.
OV - Refer to Organic Vapor
Override Switch - A switch that provides a secondary means to disarm or override a security system in the event the primary means is unavailable. This switch is also often used for valet or other security programming functions. Refer to Emergency Override.
Oversampling - Doubling or quadrupling (or by even a higher factor of 2 squared) the sampling frequency during the digital to analog process to obtain a high frequency for digital filtering.
Oxygen Free Copper (OFC) - Oxygen-free high thermal conductivity (OFHC) copper is a group of wrought high conductivity copper alloys that have been electrolytically refined to reduce the level of oxygen to .001% or below. This is the most commonly used and most reliable type of wire in car audio, as opposed to Cooper Clad Aluminum (CCA).