A.2.2 Communication Range The Bluetooth communication range is approximately 10 meters. The actual communication range differs depending on the surrounding radio wave environment, objects of interference, and the setup location. Make sure to sufficiently test the communication range when setting up a network. A.2.3 Bluetooth Frequency Bluetooth operates at a frequency of 2.4GHz. This frequency can also be used by IEEE802.11b/g wireless LAN and microwave devices. Bluetooth uses a frequency hopping method.
If a specific frequency is being used by another device and causing interference, Bluetooth technology will quickly move to a different frequency to minimize cross-talk that could prevent communication. The master device generates this frequency shifting pattern which is then followed by the slave device. A.2.4 Standby Mode When Bluetooth communication is occurring, it is in “Active Mode”. It is in “Standby Mode” when no communication is occurring. This standby mode consists of several patterns. The master device sets which standby mode to move to and how long after communication has ended to move to that mode.
A.2.5 Security Bluetooth is able to secure high level security functions due to the following points. ❏ Frequency Hopping • Bluetooth is constantly moving between frequencies. Since its pattern of frequency shifting is known only by the master and slave devices, any devices that are attempting to intercept communications cannot follow these changes. ❏ Authentication • When Bluetooth is used, authentication occurs between the host and slave devices. Data passing between authenticated devices is encrypted prior to transmission, making it difficult to intercept and decrypt.
❏ Short communication range • Bluetooth transmission strength is relatively weak and the radio wave dispersal distance short. This reduces the danger of the radio waves traveling too far and being intercepted. A-8 About Bluetooth Rev. A