Previous Year Question
Consider the following communication technologies.
Closed-Circuit Television
Radio Frequency Identification
Wireless Local Area Network
Which of the above are considered Short-Range devices/technologies?
1 and 2
2 and 3
1 and 3
1, 2 and 3
Correct Answer: D
Detailed Solution
Closed-Circuit Television (CCTV) transmits video signals to a limited number of designated monitors or recording devices instead of broadcasting them publicly. It is generally used for the surveillance of a building, campus, road or another limited area. The signal may be transmitted through a cable, optical fibre or a short-range wireless link.
Radio Frequency Identification (RFID) uses radio-frequency electromagnetic fields to identify and track tags attached to objects. An RFID system generally consists of a tag, reader and data-processing system. A passive RFID tag does not require a separate power source; it uses energy received from the reader. Its communication range may vary from a few centimetres to several metres according to the frequency, antenna and type of tag.
A Wireless Local Area Network (WLAN) connects devices through wireless communication within a limited geographical area—such as a house, office, school or campus. Wi-Fi is the most commonly used form of WLAN and is generally based on IEEE 802.11 standards. Its range is limited in comparison with a cellular network.