Infrared (IR) Communication: Basics, Features, and Applications

This tutorial covers Infrared Communication (IrDA) basics, including infrared features, IR network operation, IR spectrum, applications, advantages, and disadvantages.

Introduction

Infrared (IR) devices are used in wireless personal area networks spanning a coverage range of about 30 feet, involving laptops, computers, PDAs, and cellular phones. The infrared frequency range is between 300 GHz and 400 THz, with a wavelength range between 1 mm and 750 nm. “Infra” means below, and “red” refers to red color light. Hence, “Infrared” stands for light with a lower frequency or longer wavelength than red light.

Infrared Features

IR Spectrum

Figure-1: Light Signal Spectrum

Figure-1 depicts the light signal spectrum, including the infrared (IR) spectrum. As shown, the IR spectrum falls between the 300 GHz to 400 THz frequency region. It is further divided into near-infrared, mid-infrared, and far-infrared bands.

Infrared Devices: LED and Laser

Two infrared components are used in IR devices: LED (Light Emitting Diode) and Laser Diode.

• LED: Has a wider transmission beam and is suitable for diffuse mode configuration. It is most commonly used as a transmitting element.
• Laser Diode: Has a more focused beam and is a more efficient optical element, often used in the receiving part of an infrared communication system.

Many infrared devices, such as remote controls, PDAs, and laptops, follow rules defined by IrDA (Infrared Data Association).

How Infrared Communication Network Works

Fig-1: Infrared Communication Network

• Infrared communication has two configuration modes: point-to-point and diffuse communication.
• Point-to-point communication: Both transmitter and receiver infrared devices should be placed in the line of sight of each other without any obstacles in between.
• Diffuse communication: Transmitter and receiver IR devices should be close to each other but do not need to be in the direct line of sight. Most commercial IR products operate efficiently within 15 degrees of each other.
• Infrared detectors operate at a frequency of 38.5 KHz.

Infrared (IR) Advantages

• Security: Communication is point-to-point or line of sight, making it difficult for intruders to intercept data.
• Low Power Consumption: IR devices consume less power, extending battery life.
• Cost-Effective: IR devices are less costly.

Infrared (IR) Disadvantages

• Line of Sight Limitation: Difficult to control devices not in the line of sight.
• Single Device Control: Can control one device at a time.
• Data Transfer Rate: Maximum data transfer rate is about 4 Mbps.
• Stability Required: Devices should remain stable during data transfer.
• Environmental Sensitivity: Hard obstacles (doors, walls), bright sunlight, smoke, dust, and fog affect infrared communication.
• Eye Safety: Although infrared waves are invisible, high-power transmissions can damage eyes.

Infrared Communication Applications

• PDAs
• Phones
• Organizers
• Printers
• Cameras
• Laptops and notebooks
• TV Remote controls
• IR Spectroscopy
• IR Photography

This infrared tutorial is useful for beginners in the infrared communication domain.