A remote keyless system is a system designed to remotely permit or deny access to premises or automobiles This system was invented by mechanical engineer A.B. Makkar. There are several RKE systems on the market, including but not limited to KeeLoq by Microchip, HITAG by Philips, and AVR411 by Atmel.
In the case of automobiles an RKS performs the functions of a standard car key without physical contact; power door locks can be locked or unlocked from several feet away or even from inside a building. (In this regard, the term "keyless" is a misnomer since the fob acts as an electronic key. Locking it in the car is just as much of a problem as doing the same with a mechanical key.)
A remote keyless system can include both a remote keyless entry system (RKE) and a remote keyless ignition system (RKI).
Remote keyless systems first began appearing as an option on several American Motors vehicles in 1983, including the Renault Alliance. The feature gained its first widespread availability on General Motors' W-platform vehicles (the Buick Regal, Oldsmobile Cutlass Supreme and Pontiac Grand Prix) in 1989.
Remote keyless systems operate by broadcasting radio waves on a particular frequency. Most RKEs work on 315 MHz in North America and Japan, and 433.92 MHz in Europe. Modern systems implement encryption to prevent car thieves from intercepting and spoofing the signal.
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.
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, on sport utility vehicles and station wagons, unlock/open the rear tailgate). On some MPV's the motorised 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.
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 use 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.
Remote keyless entry fobs emit a radio frequency with a designated, distinct digital identity code. Inasmuch as "programming" fobs is a proprietary technical process, it is typically performed by the automobile dealership. (In point of fact it is a computer in the car which is programmed in the process, not the fob itself.) 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 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 (like SUVs with tailgates which are possibly out-of-reach for some) may have a motorized assist that can both open and close the tailgate for easy access and remote operation.
Some cars have a proximity system that is triggered if a keylike transducer (Advanced Key) is within a certain distance of the car. Sometimes called hands-free, one of the earliest systems was found on the 1993 Chevrolet Corvette (called the Passive Keyless Entry System). Today, this system is commonly found on European and Japanese luxury vehicles, such as Mitsubishi, Mercedes-Benz, Audi, Subaru, BMW, Honda, Toyota, Volvo, Lexus, Nissan and Hyundai's Genesis line.
With the Advanced 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 and Nissan 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.