問21
頻出度★☆☆
携帯電話機や家電などで用いられる無線通信の標準化規格である Bluetooth の活用事例はどれか。
平成25年度 秋期 ITパスポート試験 問21
テクノロジ系コンピュータ構成要素 › 入出力デバイス
This question's explanation and your answers so far.
解説
問 21
- ア
正解 Bluetooth is a standardized wireless communication specification that uses radio waves in the 2.4GHz band to connect devices over a short range of roughly a few meters up to about 10 m. It was originally aimed at replacing cable connections with wireless ones, so its typical uses are links between a main unit and its peripherals: a mobile phone and a headset, a PC and a mouse or keyboard, and a game console and its controllers. Once the devices are registered with each other in advance, a process called pairing, one master device can be connected to several slave devices at the same time. Choice ア, wirelessly connecting two controllers to a single home game console, is exactly this kind of one-to-many short-range device connection, so it is a correct example of Bluetooth in use.
Incorrectイ
A car navigation system determines its current position by receiving signals from satellites, which is the mechanism of GPS (Global Positioning System). It receives positioning signals sent one way from satellites tens of thousands of kilometers above the earth, so its purpose, communication distance, and frequency all differ from those of Bluetooth, which handles short-range device-to-device communication.
Incorrectウ
Reading a QR code is an optical process: a camera captures the black-and-white pattern of the two-dimensional code and the image is then analyzed. No data is exchanged by radio waves at all, so it is not wireless communication in the first place and does not qualify as an example of Bluetooth.
Incorrectエ
Reading an IC transit card held over an automatic ticket gate uses contactless IC card (RFID) technology, typified by NFC and FeliCa. It uses the 13.56MHz band, its communication distance is only a few centimeters, and the card itself has no battery and is powered by the electromagnetic waves from the reader. This is proximity communication completed in the instant the card is held over the reader, a different specification from Bluetooth, which pairs devices and keeps them connected over a range of several meters.
ここがポイント
- Bluetooth is a short-range wireless communication specification using the 2.4GHz band (a range of roughly a few meters up to about 10 m); its typical use is to connect a main unit with peripherals (headsets, mice, keyboards, game controllers, and so on) without cables by means of pairing.
- Remember wireless technologies by distinguishing their purpose and range: GPS = receiving positioning signals from satellites; NFC / FeliCa (RFID) = contactless IC cards at a few centimeters; Bluetooth = device-to-device connections at a few meters; wireless LAN (Wi-Fi) = network connections at tens of meters. QR codes are not wireless at all but an optical reading technology.
用語