Infrared &

Radio Transmission

Infrared Transmission

• Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light

• Employed in short-range communication among computer peripherals and personal digital assistants and electronic devices

• Uses infrared light-emitting diodes

• Receiver uses a silicon photodiode to convert the infrared radiation to an electric current

• Responds only to the rapidly pulsing signal created by the transmitter, and filters out slowly changing infrared radiation from ambient light

Propagation

Uses

• Short Range Communication

• Indoor use

Advantages

• Simple Circuit• Cheap• Low Power Consumption• No Licenses Needed• Higher Security• Simple Shielding• Portable

Disadvantages

• Works ONLY on Line-of-Sight (LOS) Mode

• Short Range

• Blocked by common materials: people, walls, etc

• Low bandwidth

• Speed is comparatively slow

Examples

• Remote Control

• Mobile Phones

Radio Transmission

• Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light

Propagation

• Radio waves travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space

• Information is carried by systematically changing (modulating) some property of the radiated waves, such as amplitude, frequency, phase, or pulse width

Uses

• Audio• Telephony• Video• Navigation• Radar• Data (Digital Radio)• Radio control

Advantages

• Simple Circuit

• Cheap

• No Licenses Needed

• High Speed/Bandwidth

• Covers Large Areas (Penetrates through walls)

Disadvantages

• Limited number of free frequency bands

• Shielding is difficult

• Interference with other electrical devices

• Greater Power Consumption

• Limited Spectrum of Frequency

Examples

• FM Channels

• Walkie Talkies