Automotive Electronics Glossary


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ABS: Antilock Braking System; keeps the tires from locking while braking; the car can still be handled without losing control.

ACC: Adaptive Cruise Control; the ACC system scans the area ahead of a car for objects - mainly other cars - and applies the brakes automatically if a collision is likely to occur.

Accumulator: In a computer, the basic work register of the computer. In hydraulics or pneumatics, a device for storing pressurized fluid.

Actuator: A device which performs a mechanical action in response to an input signal, which may be either electric or fluidic.

A/D: Analog-to-Digital converter; an electronic circuit or device that converts an analog input signal into a digital signal.

ADIS: Advanced Driver Information Systems; a combination of infrastructure and in-vehicle displays that communicate information to the driver (emergency and general.)

A/F: Air/Fuel ratio.

Air Induction System: The components through which combustion air is induced into the engine.

Ali-Scout: Siemens' Navigation and Traffic Management System that utilizes in-vehicle electronics/displays, traffic signal based infrared beacons and a central computer.

Alternate Fuel: Fuels other than gasoline, which include methane, ethanol, compressed natural gas, electricity, etc.

Analog Circuit: An electronic circuit which amplifies, reduces or otherwise alters a voltage signal which is a smooth or continuous copy of some physical quantity.

Assembly Language: An abbreviated computer language which humans can use to program computers. Assembly language eventually is converted into machine language so that it can be understood by a computer.

ATIS: Advanced Traveler Information Systems; vehicle features which assist the driver with planning, perception, analysis and decision-making.

ATMS: Advanced Traffic Management Systems; an array of institutional, human, hardware, and software components designed to monitor, control, and manage traffic on streets and highways.

AVC: Automated Vehicle Classification; used in CVO, AVC electronically identifies a vehicle's type. Using this system decreases the amount of time required at border crossings by reducing the amount of paperwork drivers have to process.

AVCS: Advanced Vehicle Control Systems; vehicle systems that automate current functions, such as distance-keeping, lane-changing, ramp merging, etc.

AVI: Advanced Vehicle Identification.

BabySmart: Childseat Presence Orientation Detection (CPOD); pressure sensitive foil with integrated antenna and resonators in the childseat to keep the airbag from firing with full capacity if necessary.

BDC: Bottom Dead Center; in an engine, lowest position of a piston in a cylinder during the stroke.

Bike Carrier: bike carrier gives you easy access to the boot and features detachable and easy to move frame holders.

Bit: A binary digit, the smallest piece of data a computer can manipulate.

Block Diagram: A system diagram that shows all of the major parts and their interconnections.

BSCO: Brake Specific CO; in an engine, the ratio of the rate at which carbon monoxide leaves the exhaust manifold to the brake horsepower.

BSFC: Brake Specific Fuel Consumption; in an engine, the ratio of the rate at which fuel is flowing into the engine to the brake horsepower being generated.

BSHC: Brake Specific HC; in an engine, the ratio of the rate at which hydrocarbons leave the exhaust manifold to the brake horsepower.

BSNO: Brake Specific NOx; in an engine, the ratio of the rate at which oxides of nitrogen leave the exhaust manifold to the brake horsepower.

Byte: Eight bits dealt with together.

CAFE: Corporate Average Fuel Economy; the annual model year fuel economy average for all automobiles produced by an automobile manufacturer.

Capacitor: An electronic device that stores an electrical charge.

Catalyst: A material which speeds up or stimulates a chemical reaction without being significantly chemically altered by the reaction.

Catalytic Converter: A device which enhances certain chemical reactions reducing the levels of undesirable exhaust gases from an engine.

Closed-Loop Fuel Control: In an engine, a mode where input air/fuel ratio is controlled by using an exhaust oxygen sensor as the input reference.

CO: Carbon Monoxide; an undesirable chemical combustion of a hydrocarbon fuel product due to imperfect combustion.

Combinational Logic: Logic circuits whose outputs depend only on the present logic inputs.

Combustion: The burning of the fuel-air mixture in an engine cylinder.

Comparator, Analog: An electronic device that compares the voltages applied to its inputs.

Compression Ratio: In an engine, the ratio of the cylinder volume at BDC to cylinder volume at TDC.

Control Variable: The inputs and outputs which a control system manipulates and measures to keep proper control.

Conversion Efficiency (Catalytic Converter): The efficiency with which undesirable exhaust gases are reduced to acceptable levels or are converted to desirable gases.

Coverage: Commonly known as auto insurance, a plan or policy that assures that a third party company will participate in the expenses in case of damage or theft.

CPOD: Childseat Presence Orientation Detection; a system that detects the presence and orientation of a childseat on the front passenger seat. Jointly developed with IEE. Also known as BabySmart.

CPU: Central Processing Unit; the calculator portion of a computer.

Cutoff: A transistor operating mode where very little current flows between the collector and emitter.

Custom Wheels: Selection of wheels customized to the owners likeing.

CVO: Commercial Vehicle Operations; the application of ITS technology to commercial vehicles.

D/A (also DAC): Digital-to-Analog Converter; a device that produces a voltage which is proportional to the digit input number.

Damping Coefficient: A parameter that affects a system's time response by controlling the rate at which energy can be added to or removed from the system.

Dead-Reckoning: A technique that calculates the current location of a vehicle by measuring the distance and direction that the vehicle has traveled since leaving a known starting point.

DEKA: Siemens' fuel injector trade name, available in low and high pressure designs.

DEMUX: Demultiplexer, a type of electronic switch used to select one of several output lines.

Diesel: A class of internal combustion engine in which combustion is initiated by the high temperature of the compressed air in the cylinder rather than an electrical spark.

Differential Correction: A technique for overcoming GPS position determination errors; GPS receivers are placed at precisely identified control locations to measure the difference between indicated GPS positions versus actual positions.

Digital Circuits: Electronic circuits whose outputs can change only at specific instances and between a limited number of different voltages.

Diode: A semiconductor device which permits current to flow in only one direction (analogous to a check valve, in fluid handling.)

Display: A device that indicates in human readable form the result of a measurement of some variable.

Drivetrain: The combination of mechanisms connecting the engine to the driven wheels, typically the transmission, driveshaft, and differential in a rear wheel driven vehicle.

Dwell: In an engine, the time allowed for current to build in the primary circuit of the ignition coil for each spark generation.

Dynamometer: A device used to place a load on an engine and measure its performance.

ECU: Electronic Control Unit.

EEGR: Electronic Exhaust Gas Recirculation; a procedure in which a portion of exhaust is introduced into the intake of an engine primarily for NOx reduction.

EGO: Exhaust Gas Oxygen; the concentration of oxygen in the exhaust of an engine. An EGO sensor (also O2 sensor, or oxygen sensor) is used in closed-loop fuel control systems to indicate rich or lean A/F.

Electronic Feedback Carburetor: A fuel metering device in which the air/fuel ratio is controlled by continual variations of the metering rod position or air bypass modulation in response to an electronic control signal.

Electronic Throttle Control (ETC): Acceleration peddle controls the throttle by means of a computer-controlled stepping motor in lieu of a conventional linkage from peddle to throttle.

Electronic Valve Timing (EVT): A system where the opening/closing times and lift of cylinder valves are controlled by computer.

Engine Calibration: The values for all controllable functions including air/fuel, spark advance and EGR at specified operating conditions.

Engine Crankshaft Position: The angular position of the crankshaft relative to a reference point.

Engine Mapping: A procedure of experimentally determining the performance of an engine at selected operating points and recording the results.

Equivalence Ratio: Actual air/fuel ratio divided by the air/fuel ratio at stoichiometry.

Evaporative Emissions: Evaporated fuel from the carburetor or fuel system which mixes with the surrounding air.

FHWA: Federal Highway Administration; branch of the U.S. DOT.

Foot-Pound: A unit of torque corresponding to a force of one pound acting on a one foot level arm.

Frequency Response: A graph of a system's response to a different frequency input signals.

Fuel Injector (Electronic): An electro-mechanical device that precisely meters fuel into an internal combustion engine based on a time electronic input.

Fuel Pressure Regulator: Maintains fuel pressure to fuel injector to help insure proper quantity is delivered to engine.

Gain: The ratio of a system's output magnitude to its input magnitude.

Geodetic Coordinates: A system of geographic position referencing. Angular measurements of latitude and longitude are projected onto a well-defined reference ellipsoid that approximates the earth's irregular shape.

GPS: Global Positioning System; an array of satellites, deployed and maintained by the U.S. Department of Defense, which can be monitored to triangulate an accurate position on the earth's surface.

HC: Hydrocarbon Chemicals, such as gasoline, formed by the union of carbon and hydrogen.

IAFS/IAFM: Integrated Air Fuel System/Integrated Air Fuel Module; complete intake manifold system that includes all fuel and air delivery requirements and many final dress items.

IEEE: Institute of Electrical and Electronics Engineers, Inc.; a professional society and standards-making body.

Ignition Timing: The time of occurrence of ignition measured in degrees of crankshaft rotation relative to TDC.

Immobilizer: Theft-deterrent system that uses a transponder inside the ignition key to electronically enable an operational control unit in the vehicle to start the car.

Inductor: A magnetic device that stores energy in a magnetic field produced by flowing current.

Infrared: A communication medium that employs wavelengths longer than those of visible light.

Instrumentation: Apparatus (often electronic) which is used for measurement or control; and for display of measurements or conditions.

Integral Amplifier: A control system component whose voltage output changes at a rate proportional to its input voltage.

Integrated Circuit: A semiconductor device that contains many circuit functions on a single chip.

Interrupts: An efficient method to quickly request a computer's attention to a particular external event.

ISO: International Standards Organization.

ISU: Intelligent Switching Unit; provides integration and functionality in the cockpit module with reduced cost, thanks to a new human-machine interface, impulse coded steering wheel command, integrated low current switches and smart key.

ITS: Intelligent Transportation System; an umbrella term, includes an advanced technology approach to traffic management; original name was IVHS.

IVHS: Intelligent Vehicle Highway System; now referred to as ITS.

Lead Term: A control system component that anticipates future inputs based on the current signal trend.

LED: Light-Emitting Diode.

Limit Cycle: A mode of control system operation in which the controlled variable cycles between extreme limits with the average near the desired value.

Linear Region: A transistor operating mode where the collector current is proportional to the base current.

Logic Circuits: Digital electronic circuits that perform logical operations such as NOT, AND, OR, and combinations of these.

Lookup Table: A table in computer memory that is used to convert an important value into a related value from the table.

MAP: Manifold Absolute Pressure; the absolute pressure in the intake manifold of an engine.

Mass Air Flow Sensor: A device mounted in the engines air induction system that provides an electrical signal representing the instantaneous rate of mass air flow.

Mathematical Model: A mathematical equation or equations which can be used to numerically compute a system's response to a particular input.

Mechatronics: The introduction of electronic controls into mechanical components.

Memory Card: A plug-in computer memory card containing prerecorded information; may function as mass storage for on-board navigation systems; also called IC card and Flash Memory.

Microcomputer: A small computer that uses an integrated circuit which contains a central processing unit and other control electronics.

Multiplexing: A technology that enables more than one signal to be transmitted on the same wire between two or more electronic modules. The advantage of multiplexing is that it reduces wiring in the vehicles, thus reducing cost, weight, and package size of the wire harness.

MUX: Multiplexer; a type of electronic switch used to select one of several input lines.

Navigable Database: A digital streetmap database containing sufficient detail and scope to support driver and vehicle guidance applications.

NO, also NOx: The various oxides of nitrogen.

NVH: Noise and Vibration Harshness.

Op Code: A number which a computer recognizes as an instruction.

Open-Loop Fuel Control: A mode where engine input air/fuel ratio is controlled by measuring the mass of input air and adding the proper mass of fuel to obtain a desired ratio.

Operational Amplifier: A standard analog circuit component with two inputs, one output and a very high voltage gain.

Optimal Damping: The damping which produces the very best time response.

Peripheral: An external input-output device which is connected to a computer.

Phase Shift: A measure of the delay between the time an electrical signal enters a system and the time it shows up at the output.

PPD: Passenger Presence Detection; a sensor system that is able to detect the presence of a passenger. Different systems are known as Infrared Scanning Weight Sensing, Capacitive Measurement.

Proportional Amplifier: A control system component that produces a control output proportional to its input.

Qualitative Analysis: A study that reveals how a system works.

Quantitative Analysis: A study that determines how well a system performs.

QuickScout: An in-vehicle ATIS device that uses the cellular telephone infrastructure to provide a driver with turn-by-turn route guidance, real-time traffic information, and emergency/roadside assistance capabilities. Developed by Siemens.

RAM: Random Access Memory; a type of read/write memory.

Random Error: A measurement error which is neither predictable nor correctable, but contains some statistical nature.

RFID Labels (Radio-Frequency Identification): RFID Labels can be applied or integrated into a product for the purpose of identification and tracking using radio waves. This has been a positive break through as it has improved the efficiency of inventory tracking and management. .

ROM: Read Only Memory; permanent memory used to store permanent programs.

Route Guidance Database: The detailed information required to enable a computer to generate a high quality driving route between two locations; information includes geometry, street names, addresses, speed limits, turn restrictions, one-way restrictions, road levels, and roadway connections.

RPM: Revolutions Per Minute; the speed of rotation of the crankshaft in an engine or other rotation shaft.

SAE: Society of Automotive Engineers.

Sample and Hold: The act of measuring a voltage at a particular time and storing that voltage until a new sample is taken.

Sampling: The act of periodically collecting or providing information about a particular process.

Semiconductor: A material that is neither a good electrical conductor nor a good electric insulator.

Sensor: An energy conversion device that measures some physical quantity and converts it to an electrical quantity.

Sequential Logic: Logic circuits whose output depends on the particular sequence of the input logic signals.

SI Engine: Abbreviation for spark ignition, internal combustion engine.

SIR Sensor: Supplemental inflatable restraint sensor.

Signal Processing: The alteration of an electrical signal by electronic circuitry; used to reduce the effects of systematic and random errors.

Skid: A condition in which the tires are sliding over the road surface rather than rolling; usually associated with braking or turning.

Slip: The ratio of the angular speed of the driving element to the angular speed of the driven element of a torque converter; also, the condition in which a driven tire loses traction so that the driving torque does not produce vehicle motion.

"Smart" Air Bag: System that intelligently adjusts the vehicle restraints to optimize occupant protection.

Smart CardTMSiemens' trade name for passive entry and ignition.

Smart Key: Electronically coded key used both to enter and start the vehicle.

Software: The computer program instructions used to tell a computer what to do.

Solenoid: An electrically charged coil of insulated wire which produces a magnetic field within the coil.

Spark Advance: The number of degrees of crankshaft rotation before TDC where the spark plug is fired (see ignition timing.)

Spark Timing: The process of firing the spark plug at the proper moment to ignite the combustible mixture in the engine cylinders.

Speed-Density: A method of calculating the inducted mass airflow of an internal-combustion engine-based MAP RPM, and mapped volumetric efficiency at a constant temperature.

Spread Spectrum: Type of radio transmission; reduces interference and jamming, and allows multiple user communications; originally developed by the military.

Stoichiometry: The theoretical air/fuel ratio for perfect combustion; it enables exactly all of the fuel to burn using exactly all of the oxygen in the air.

System: A collection of interacting parts.

Systematic Error: A measurement error in an instrumentation system which is predictable and correctable.

Tail lights: Part of the rear end of the vehicle which produces light when braking and indicating.

TBFI: Throttle-Body-Fuel Injector; a fuel metering actuator in which the air/fuel ratio is controlled by injecting precisely controlled amounts of fuel into the air stream entering the intake manifold.

TDC: Top Dead Center; the highest point of the piston during its stroke.

Tetrastar: Autonomous route guidance system from Siemens; uses GPS and gyroscope. Gives driver turn-by-turn vehicle route guidance.

Throttle Angle: The angle between the throttle plate and a reference line; engine speed increases as the angle increases.

Torque Converter: A form of fluid coupling used to transmit torque from the power plant to the rest of the drive train.

Torque: The twisting force of the crankshaft or other driving shaft.

Transfer Function: A mathematical equation which, when graphed, produces a system's frequency response plot.

Transistor: An active semiconductor device that operates like a current valve.

Transponder: Batteryless electronic code memory which transmits and receives low frequency messages upon activation by an external electromagnetic field.

Transport Delay: The time required for a given mass of fuel and air to travel from the intake manifold through the engine to the EGO sensor in the exhaust manifold.

Turn-By-Turn Route Guidance: A method of providing route guidance by sequentially delivering upcoming maneuver information to the driver visually and/or audibly as the route is driven.

Used Cars:Term to describe secondhand or preowned cars.Often bought at authorised car dealers.

User Services: Services available to users (drivers) of an ITS equipped roadway, as set forth by ITS America. The 29 services are arranged in 7 groups as follows:

  1. Travel and Transportation Management
    - En-Route Driver Information; Route Guidance; Traveler Services Information; Traffic Control; Incident Management; and Emissions Testing and Mitigation
  2. Travel Demand Management
    - Pre-Trip Travel Information; Ride Matching and Reservation; Demand Management; and Operations
  3. Public Transportation Operations
    - Public Transportation Management; En-Route Transit Information; Personalized Public Transit; and Public Travel Security
  4. Electronic Payment
    - Electronic Payment Services
  5. Commercial Vehicle Operations
    - Commercial Vehicle Electronic Clearance; Automated Roadside Safety Inspection; On-Board Safety Monitoring; Commercial Vehicle Administrative Processes; Hazardous Materials Incident Response; and Commercial Fleet Management
  6. Emergency Management
    - Emergency Notification and Personal Security; and Emergency Vehicle Management
  7. Advanced Vehicle Control and Safety Systems
    - Longitudinal Collision Avoidance; Lateral Collision Avoidance; Intersection Collision Avoidance; Vision Enhancement for Crash Avoidance; Safety Readiness; Pre-Crash Restraint Deployment; and Automated Highway Systems

Volumetric Efficiency: The pumping efficiency of the engine as air is drawn into the cylinders.