The transmission of data or voice information over infrared (IR) light. Infrared data transmission is often used to connect laptops or Personal Digital Assistants (PDAs) to peripherals (such as printers) or to desktop computers for synchronizing work files.
The most popular computer industry standard for infrared transmission is the IrDA Data standard developed by the Infrared Data Association (IrDA).
IR is light that is beyond the red end of the visible spectrum. Wavelengths in the range of 770 to 1400 nanometers are called the near infrared region of the electromagnetic spectrum, while longer wavelengths are called the far infrared. An IR transducer consists of a driver and an IR emitter that can both transmit and receive infrared transmissions. The transducer is connected to an encoder/decoder that interfaces with the computer or peripheral’s universal asynchronous receiver-transmitter (UART) for asynchronous serial transmission between the devices.
IrDA devices that use the IrDA Data protocol suite initiate a connection using the discovery functions of the Infrared Link Management Protocol (IrLMP) and establish the primary and secondary stations using the Infrared Link Access Protocol (IrLAP). The secondary station then adjusts its data speed to match the primary station and establishes a serial communication link.
Remember that IrDA devices have severe distance limitations and require a direct line of sight between them in order to communicate, and that outdoor communication can be adversely affected by fog and other bad weather.