1. Closed-circuit Television
2. Radio Frequency Identification
3. Wireless Local Area Network
Which of the above are considered Short-Range devices/technologies?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Ans: d
Explanation:
Wireless devices that transmit low power levels and operate over distances of up to a few hundred meters are Short Range Devices (SRD). They mostly use Radio frequencies to operate in a small area. Short range communications as the systems providing wireless connectivity within a local sphere of interaction.
Short Range Devices (SRD) are radio devices that offer a low risk of interference with other radio services, usually because their transmitted power, and hence their range, is low. The definition ‘Short Range Device’ may be applied to many different types of wireless equipment, including various forms of:
- Access control (including door and gate openers)
- Alarms and movement detectors
- Closed-circuit television (CCTV)
- Cordless audio devices, including wireless microphones
- Industrial control
- Local Area Networks
- Medical implants
- Metering devices
- Remote control
- Radio frequency identification (RFID)
- Road Transport Telematics
- Telemetry.
They have a low effective radiated power (ERP) of typically 25-100 mW and thus do not interfere with other radio services. The frequencies used by these devices are called SRD frequencies. Other SRD wireless technologies include Bluetooth, Wi-Fi, near-field communication (NFC), ultra-wideband (UWB).
Hence, option d is correct.
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