Have you ever wondered how your TV remote works? How is that you are able to switch channels being seated at a place? It is always so fascinating to learn about the devices you use in daily life, isn’t it?
The link between the TV and the remote is the infrared rays. If there is any obstacle in the path of this IR rays, the instrument does not function.
How is Infrared used in communication?
Infrared (IR) communication allows devices to communicate with each other in a short-range. Infrared or IR as the name goes falls into a band of the electromagnetic spectrum with its wavelength lying between 700 nanometres to 100 micrometers. IR is not visible to the human eye and can provide effective communication over a short-range. This IR technology no more exists in present-day smartphone technology.
The above images show an IR LED (left) and IR Photosensor (right) which are present at the transmitter and receivers of an IR communication module.
Not all the IR waves will be received by the receiver. Whenever an IR wave is sent by the transmitter it is modulated prior transmission. Modulation is a process wherein a pattern is assigned to the signal prior to transmission. The same pattern is used at the receiver to demodulate the wave and understand the message that was received.
A common modulation scheme used in IR communication is called the 38 kHz modulation. There are very few natural sources that have the regularity of a 38 kHz signal, so an IR transmitter sending data at that frequency would be unique when compared with the ambient IR. 38 kHz modulated IR data is the most commonly used but however any other frequencies can also be used as well.
When you hit a key on your remote, the transmitting IR LED will blink very quickly for a fraction of a second, transmitting encoded data to your appliance.
Infrared communication in mobiles
Pic courtesy: file saves
IR communication played a very important role during the early years of the 21st century. IR communication was used in mobile phones for transmission of audio/video/documents using IR ports present in the mobile phones. The phones consisted of IR transceivers and an IR port to establish communication. As we already know that IR communication is the line of sight communication and hence the two devices have to be brought together such that the ports faced each other to ensure data transmission. The setup for IR communication can be seen in the figure. When a user wishes to transmit the data, he points the IR port of his device towards the port of the recipient device and enables the transmission by using the application to interface the IR port in his device. Once the data transmission is complete the communication link is deactivated and the user is notified about the data received.
Although radio-based Wi-Fi and Bluetooth technologies have taken over IR technology in mobile phones, but still IR technology finds its application in providing low cost and low power communication in devices/appliances used by us in our day to day life.
The only doubt in your mind at this moment would be about the applications of IR, right?
Let’s see the applications of IR.