Remote keyless system
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A keyless entry system is an electronic lock that controls access to a building or vehicle without using a traditional mechanical key. The term keyless entry system originally meant a lock controlled by a keypad located at or near the driver's door, that required pressing a predetermined (or self-programmed) numeric code for entry. These systems, having evolved into a hidden touch-activated keypad, are still available on certain Ford or Lincoln models.
The term remote keyless system (RKS), also called keyless entry or remote central locking, refers to a lock that uses an electronic remote control as a key which is activated by a handheld device or automatically by proximity.
Widely used in automobiles, an RKS performs the functions of a standard car key without physical contact. When within a few yards of the car, pressing a button on the remote can lock or unlock the doors, and may perform other functions. A remote keyless system can include both a remote keyless entry system (RKE), which unlocks the doors, and a remote keyless ignition system (RKI), which starts the engine.
Remote keyless systems first began appearing on the French made Renault Fuego in 1982, and as an option on several American Motors vehicles in 1983, including the Renault Alliance. The feature gained its first widespread availability in the U.S. on several General Motors vehicles in 1989.
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Keyless remotes contain a short-range radio transmitter, and must be within a certain range, usually 5–20 meters (15–60 ft), of the car to work. When a button is pushed, it sends a coded signal by radio waves to a receiver unit in the car, which locks or unlocks the door. Most RKEs operate at a frequency of 315 MHz for North America-made cars and at 433.92 MHz for European, Japanese and Asian cars. Modern systems implement encryption to prevent car thieves from intercepting and spoofing the signal. Earlier systems used infrared instead of radio signals to unlock the vehicle, such as systems found on Mercedes-Benz, BMW and other manufacturers.
The system signals that it has either locked or unlocked the car usually through some fairly discreet combination of flashing vehicle lamps, a distinctive sound other than the horn, or some usage of the horn itself. A typical setup on cars is to have the horn or other sound chirp twice to signify that the car has been unlocked, and chirp once to indicate the car has been locked. For example, Toyota, Scion, and Lexus use a chirp system to signify the car being locked/unlocked. While two beeps means that driver's door is unlocked, four beeps means all doors are unlocked. One long beep is for the trunk or power tailgate. One short beep signifies that the car is locked and alarm is set.
The functions of a remote keyless entry system are contained on a key fob or built into the ignition key handle itself. Buttons are dedicated to locking or unlocking the doors and opening the trunk or tailgate. On some minivans, the power sliding doors can be opened/closed remotely. Some cars will also close any open windows and roof when remotely locking the car. Some remote keyless fobs also feature a red panic button which activates the car alarm as a standard feature.
Some cars' engines with remote keyless ignition systems can be started by the push of a button on the key fob.
On cars where the trunk release is electronically operated, it can be triggered to open by a button on the remote. Conventionally, the trunk springs open with the help of hydraulic struts or torsion springs, and thereafter must be lowered manually. Premium models, such as SUVs and estates with tailgates, may have a motorized assist that can both open and close the tailgate for easy access and remote operation.
For offices, or residences, the system can also be coupled with the security system, garage door opener or remotely activated lighting devices.
The operating range of keyless remotes varies widely between manufacturers. E.g., Ford uses 20 m for Europe and North America and 5m for Japan and other markets where the transmitted power restrictions are much greater. The range is either measured from the skin of the car or from a nominal central point. The range around the vehicle is not linear as corner pillars and small window apertures attenuate the signal, hence reducing its range.
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Remote keyless entry fobs emit a radio frequency with a designated, distinct digital identity code. In as much as "programming" fobs is a proprietary technical process, it is typically performed by the automobile manufacturer. In general, the procedure is to put the car computer in 'programming mode'. This usually entails engaging the power in the car several times while holding a button or lever. It may also include opening doors, or removing fuses. The procedure varies amongst various makes, models, and years. Once in 'programming mode' one or more of the fob buttons is depressed to send the digital identity code to the car's onboard computer. The computer saves the code and the car is then taken out of programming mode.
As RKS fobs have become more prevalent in the automobile industry a secondary market of unprogrammed devices have sprung up. Some web sites sell steps to program fobs for individual models of cars as well as accessory kits to remotely activate other car devices.
On early keyless entry remotes, the remotes can be individually programmed by the user, by pressing a button on the remote, and starting the vehicle. However, newer keyless entry remotes require dealership or locksmith programming via a computer. The Infrared keyless entry systems offered user programming, though radio frequency keyless entry systems mostly require dealer programming.
Smart key 
Some cars have a proximity system that is triggered if a keylike transducer is within a certain distance of the car. Sometimes called hands-free or advanced key, one of the earliest systems was found on the 1993 Chevrolet Corvette (called the Passive Keyless Entry System) and in Mercedes-Benz vehicles from 1998. Today, this system is commonly found on a variety of vehicles.
With the smart key system, a vehicle can be unlocked without the driver needing to physically push a button on the key fob to lock or unlock the car and is also able to start or stop the ignition without physically having to insert the key and turning the ignition. Instead, as you approach the vehicle, the vehicle senses that the key (located in a pocket, purse, etc.) is approaching the vehicle. When inside the car's required distance there are two methods typically used by auto manufacturers to unlock the doors:
- Method 1 — Once the keyholder is in the car's "bubble" (the required distance from the vehicle for the key to be recognized) the car will automatically unlock the driver's door.
- Method 2 — Once inside the car's "bubble" the car doesn't unlock the door unless the keyholder touches one of the sensors located behind the door handles. As others attempt to get in, the system senses that the driver is within the "bubble" and as they touch the sensors behind their door handles, the car will unlock their door.
In certain vehicles, there are also various functions built into the transmitter to perform various tasks. For instance, pressing the unlock button twice and keeping the button depressed on the second push allows the keyholder to roll down certain pre-programmed windows and/or the sunroof. Other functions range from turning on the headlights and various electronic equipment (factory or aftermarket). On some Toyota, Nissan and Hyundai vehicles, the system prevents the driver or passenger from accidentally locking the keys in the car, via the sensor that detects whether the keyholder is within the "bubble" area outside the vehicle.
A security key system is embedded into most modern vehicle's keys. A small chip rests on the vehicle's key or under the plastic key cover. When any key is inserted into the ignition, the ignition is coded. The key sends its security code to the ignition, which also has its own security code, and if the security codes match, the vehicle will start when the key is turned. However, if the key codes do NOT match, the vehicle will NOT start when the key is turned. Some early examples of this technology include Chrysler Corporation's Sentry Key System, or General Motors's PASSKey System. Some security keys can be programmed by the user, though most of these keys have to be programmed by a dealership or locksmith via a computer. You cannot have these keys copied at any hardware store or auto parts store.
See also 
- Job, Ann. "Driving Without Car Keys". MSN Autos. Retrieved 27 February 2012.
- "1980-1985 RENAULT Fuego Turbo". Octane. Retrieved 27 February 2012.