written 5.6 years ago by |
1) IrDA:
IrDA is a serial half duplex, line of sight based wireless technology for data communications between devices
The remote control of TV ,VCD players etc. works on infrared data communication principal.
Infrared communication technique uses infrared waves of the electromagnetic spectrum for transmitting the data.
Range from contact to at least 1 meter and can be extended to 2 meters.
Bi-directional point-to-point communication .
Data transmission from 9600 b/s with primary speed/cost steps of 115 kb/s an maximum speed up to 16 Mb/s.
Data packets are protected using a CRC.
2) Wifi
Wi-Fi is a technology for wireless local area networking with devices based on the IEEE 802.11 standards.
Wi-Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that successfully complete interoperability certification testing.
Devices that can use Wi-Fi technology include personal computers, video-game consoles, phones and tablets, digital cameras, smart TVs, digital audio players and modern printers.
Wi-Fi compatible devices can connect to the Internet via a WLAN and a wireless access point. Such an access point (or hotspot) has a range of about 20 meters (66 feet) indoors and a greater range outdoors.
Hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres achieved by using multiple overlapping access points.
Wi-Fi most commonly uses the 2.4 gigahertz (12 cm) UHF and 5.8 gigahertz (5 cm) SHF ISM radio bands.
Anyone within range with a wireless modem can attempt to access the network; because of this, Wi-Fi is more vulnerable to attack (called eavesdropping) than wired networks.