There are many types of remote controls on the market today. Below is a list and description of the most common types of remote controls and the remote control technology used. Note that there are subcategories for some types of remote control technology.
Infrared, or IR technology is a form of light just outside the visible spectrum of the human eye. When modulated and set to a specific frequency it can be used to send unique bursts of IR light to a device. Each unique infrared code is then interpreted as a specific function by the device being controlled.
Line of sight - Both remote and device being controlled must be in the same room unless a special IR repeater is used. This means that controlling a second device located in a different room, even if it is the same brand and model, will not work. Infrared light does not transmit through walls or solid objects. However, the physical properties of light mean you can bounce the infrared light off objects, or walls in a room. This why you can sometimes point an infrared remote towards the back of a room yet it will still control the device located in the opposite direction. The more reflective the surface, the more infrared light reflection will occur. Think of the infrared remote more like a common flashlight in how the light is transmitted throughout a room. Pointing the remote directly at the device you are controlling has the best accuracy. Since the IR light does spread out during transmission, you can have good results by just pointing in the general direction of the infrared receiving device.
Less Expensive - Infrared IR technology has been used as the main transmission technology in remote controls many years. Since it is an established and accurate technology it is also very common. Therefore many device manufacturers use infrared technology as the primary remote control technology. Using common technology means the components used in infrared remotes are readily available to manufacturers. An infrared remote control circuit is relatively simple for a standard dedicated remote control. Therefore the cost of IR technology is low compared to newer, or more complex technologies such as radio frequency remote controls, or WiFi. One must keep in mind that as with any type of manufacturing there are various quality levels of the components used to manufacture a remote control. These components include the PCB board used, material used for electrical contacts, the remote control IC (Integrated Circuit), and the supporting components like the infrared LED. Higher quality components can mean better performance and longer overall life of the remote control.
Battery life - Typically, battery life for an infrared remote control is much longer than the battery life of a radio frequency or WiFi remote. Battery life will of course depend on the amount of use the remote will have, the circuit design and components used, and whether the infrared remote has options like back-lighting or an LCD display. Note that 'glow keys' which glow in the dark do not affect battery life. They obtain the energy to glow from ambient light in the room. Most dedicated infrared remotes will use between 2 to 4 batteries that are typically either AAA or AA in size. Many remote controls use a single infrared "IR" LED (Light Emitting Diode). This is usually sufficient for use in most environments where distance from remote to device is about 30 to 40 feet (9 to 12 meters). Some remotes are designed with two or more IR LEDs. For these remotes more batteries may be designed into the circuit. These remotes might use 4 AAA batteries, or 4 AA batteries. The purpose of additional LEDs and power is to obtain greater distance of transmission. Since additional IR LEDs require more power, this also means batteries will be consumed faster.
Limited Regulatory Requirements - Infrared transmission devices using very low power, such as an infrared remote control, do not require the same regulatory and interference tests as a radio frequency remote control. This is an advantage if interference is a concern such as medical applications or other environments where interference from alternative technology (like radio frequency remotes) is a concern or hazard. Not having to pass regulatory testing reduces development costs by eliminating costly regulatory tests required of other types of technology.
No Licensing Fees - Simple infrared remote controls typically do not use proprietary technology. So, no licensing fees are required.
Common Devices - Most electronic technology devices controlled by a remote control use infrared technology. This is common for televisions, Satellite receivers, cable boxes, DVRs, most STB devices etc. Infrared technology is also used for controlling mechanical devices such as lifts and motors.
Typical infrared frequencies used by infrared remote controls are: 36KHz, 38KHz to 56KHz, and 455KHz. Some devices use custom infrared IR frequencies.
Radio Frequency (RF)
Radio Frequency or RF technology is a modulated wave form in the radio frequency spectrum. Remote controls using radio frequency technology can transmit unique RF codes to a host device. The host device is required to have a RF receiver capable of recognizing the RF signal from the remote. The device can then decode the signal and perform a specific action.
No line-of-sight required - Remote controls that use Radio Frequency do not require the device being controlled to be within line-of-site. Transmission frequencies used by RF remote controls will penetrate and transmit through many objects such as common house walls. However very thick walls, or walls made with more dense materials such as metal, will limit the distance of any transmission of an RF signal. Boosting the power used by the remote control can increase distance, even though some denser materials. This is a benefit if the device being controlled is not in the same room as the operator, or, if the device being controlled is behind a cabinet or in a closet.Outdoors, with no interfering objects, radio frequency signals can travel very far. Distance will depend on the technology, frequency and power.
Greater Distance - RF signals can typically be transmitted greater distances than infrared IR. With enough power and an appropriate receiver and antenna RF signals can be sent many miles or kilometers. Under 'normal' remote control applications, using similar battery power as an infrared remote, the distance difference may be 30-40 feet for infrared, and 100 feet for RF for same open air line-of-site operation.
Common Devices - RF technology can be used with multiple room viewing applications where a main device such as a satellite dish receiver is located in one room and televisions or monitors are located in another room. An RF remote control can control the main device from any room in a home. Automobile 'key fobs' are RF remote controls that are programmed with a unique RF 'key code' for a specific automobile. Garage door openers typically use radio frequency. Other applications include controlling model cars, airplanes and consumer drones. Long distance switching or gate control will also use RF technology.
Radio Frequency Technology:
Typical radio frequencies used in consumer and some industrial RF remote controls are 27MHz, 433MHz, 2.4GHz. There are also custom proprietary types of RF technology used for controlling consumer and industrial electronics. Some of these include Bluetooth, Zigbee, Z-Wave, and other proprietary technologies.
Wired Remote Controls
Some applications require that the remote control be physically wired to the device it is controlling. Control commands are sent from the remote control to the device through the attached wire. Some remote controls can be designed such that the wire can be disconnected and the remote can then be used with infrared or radio frequency signals.
No interference - Since the communication is over a wired connection there will be no interference or blocking of signals from walls or other objects.
One-to-one control - Since the wired remote is plugged into only one device there are no stray signals to accidentally interfere with or control another device. While there are programming methods to limit multi-device control used with IR and RF remote control technologies (like car key fobs), a wired remote will only control the connected device.
Methods of connecting to a wired remote control can be USB, RS-232, TTL using multiple types of standard connectors, or hard wired (not removable).
Other Remote Control Technologies
WiFi technology has been used as a method of transmitting a control signal over a wifi network, or beyond (Internet). While Wifi uses radio frequency technology, Wifi remotes are more complex than standard RF remote controls. A Wifi remote needs to be capable of logging on to a Wifi network and typically communicating using a Wifi protocol.
Using a remote control, or remote-control-like device (such as a smartphone) with WiFi capabilities allows for connecting to a WiFi network and therefore communicating with any device also connected to the same network. Control can be inside a home or business, or, over the Internet. Communication with another device set up on the network will need to be preprogrammed and the controlled device will also be required to be connected to the same WiFi network.
Combination - IR, RF, WiFi and wired
Combination Technology remote controls take several of the typical control technologies and combine them into a single remote control. This is usually done for very specific applications. For consumer devices there are 'repeater' systems available that will see an infrared code from a remote control, and then repeat the same signal through the repeater device (through a wall or cabinet) and then convert the signal back into IR to transmit to the device. Some of these repeater devices can also be used with RF remote so that the receiver is located behind a cabinet. In these applications it might be advantageous to have a remote control that will transmit IR signals to line-of-site devices in a room, but also transmit RF signals to devices in another room or located behind a cabinet yet connected to an RF to IR repeater.
REMOTE CONTROL TYPE SUBCATEGORY
Dedicated Remote Control
A dedicated remote control is a remote control that is programmed to control a single specific device, or several specific devices. Under normal operations the functionality of the remote does not change. It is 'dedicated' to the specific devices. When you purchase a television for example, it may come with a dedicated remote control that will only control the television you purchased.
Universal Library or Universal Device Remote Control (Universal Remote Control)
Many people wind up with multiple dedicated remote controls for multiple devices in their home entertainment room. TV, Cable, SAT, Tuner, etc. remote controls that come with the electronic and entertainment equipment they purchase. One method of reducing the number of remote controls one has to use to control the equipment is to use a 'library' remote, also called a Universal Remote Control or URC. A library remote is preprogrammed with most common equipment infrared codes. Using several different methods various brands and models are selected on the library remote. So, TV codes are the TV infrared codes that match your television model and will control the major functions like volume and channel. Usually only standard functions are included, so less used functions are only available by using the remote control that came with the television. These Universal Library remotes are also good if you happen to lose, or break the original remote. You can at least control most major functions. Keep in mind that typical library universal remotes are one time programmed and not updateable (though some can be updated). An older library remotes may not contain the infrared codes for a newer device. Some major brands will reuse infrared codes so a "power on" command may be the same "power on" command across multiple models of the same brand.Some Universal Remote Controls also include a learning function (see below).
Learning Remote Control
A learning remote control serves a similar purpose as the above described Universal Remote Control or Library remote but the main feature is the ability of the remote to 'learn' the infrared codes from an original remote control. Using the original remote you will teach the learning remote the infrared codes. These infrared codes are stored in memory on the learning remote for later use. Most learning remotes use a technology that ensures the memory is saved whenever you change the batteries. Some learning remote controls also come with a pre-stored 'library' of infrared codes and these are selected using the same methods used with standard URC or library remote controls. To use the learning feature one must have the original remote, or, use a URC/library remote to teach the codes. Most learning remote controls are designed to learn infrared codes from standard infrared remote controls that are sold with standard consumer devices. There are technical limits however so the learning feature may not work with all infrared remotes. Keep in mind the learning technology needs to ensure it is learning a real infrared code and not some stray light from a light bulb or the sun. These technical filters are sometimes set to ignore IR light outside typical infrared signals used with consumer devices. For the most part however they are designed for consumers using typical consumer infrared controlled devices.
Programmable Remote Control
Programmable remote controls can be infrared, radio frequency, Wifi or a combination. Programmable typically means that someone using the remote can program it either with codes to control devices or create more elaborate functions such as macros. Macros are multiple functions linked together and activated with a single press of a button on the remote. Programmable remotes can be programmed via a computer using RS-232 or USB communication, or via BlueTooth, Wifi or other wireless communication protocols. Macros can sometimes be programmed directly on the remote control, or, programmed on a computer and then loaded as a file into the remote control.