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IR Remote |
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IR Remote is a hand held, wireless device used to operate audio, video and other electronic equipment within a room using light signals in the infrared (IR) range. Infrared light requires line of sight to its destination. Low-end remotes use only one transmitter at the end of the unit and have to be aimed directly at the equipment. High-quality remotes have three or four powerful IR transmitters set at different angles to shower the room with signals.
IR Remote is a simple, cheap device that can be connected to any serial port to control most components that have infrared remote controls. A remote control is an electronic device used for the remote operation of a machine. Most control remote for electronic appliances use a near infrared diode to emit a beam of light that reaches the device.
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This light is invisible to the human eye but carries signals that are detected by the appliance, as well as by the sensor of a digital camera. Since a
long time the consumer electronics industry has been employing IR remote control to control television, VCR's and many other products.
This same technic is popular in industrial and office applications like to control your personal computer to eliminate expensive keypads and cables. It is easier to use the infrared light than cables who always crossing each other. We humans cannot see infrared light because the wavelength of infrared light is below the visible spectrum but some animals can see it and use it as a target for killing the prey. Because we do not see light we use it for remote control purposes. In remote controls the light source is a led but around us there are many objects who are emitting infrared light. The brightest source is the sun. In fact everything that radiates heat is also emitting light like flames,light bulbs,and even our body.
The only hardware you need for decoding infrared signals is an infrared receiver. There are two main principles of IR remote control using a modulated beam at a frequency about 40kHz or the second is an non-modulated beam of infrared light and has a restricted range. Three typical layers are used by IR remote controls. The names used for these layers has not been standardized. But we can call it the infrared, the modulation and the serial data.
The infrared layers is the means of transmission. We cannot see infrared light because the wavelength is too long to see. Although you cannot see the infrared beam, it behaves the same as light, so if you cannot see the target device, you cannot control it with a IR remote control. To control applications through opaque materials, radio frequency signals are used. The modulation layer refers to the fact that each burst of infrared signal is often modulated at a frequency between 32.75 kHz and 56.8 kHz. This is done to diminish the effects of ambient light. This layer, however, is optional. Some infrared formats
do not modulate their outputs, sending pulses of unmodulated infrared light instead. This is done to extend the IR remote control’s battery life and to reduce the cost of the IR remote control device. IR remote control units communicate using light waves in the Infra Red spectrum. The physical communication layer is formed by the emmiter that emits the signal and a receiver that receives the signal.
The light waves are modulated by the emitter at a frequency of 40 KHz. This is done in order to cut out other sources of IR such as electric lamps, etc. In home theater applications, IR amplifiers, also known as "IR blasters," are commonly used to distribute signals to all the components, which is essential when they reside behind a closed cabinet door. A small sensor, placed at the TV or other convenient location for the user to aim at, is wired to the amplifier. The amplifier has ports for several emitters that are wired to, and pasted directly over, the IR sensors in the equipment.
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