Bluetooth, as works
Tuesday, May 26, 2009 14:52
Bluetooth devices are usually working at 2.4 GHz in the license, free, available worldwide ISM band radio. The advantage of this volume includes worldwide availability and compatibility. A disadvantage, however, that the devices should be in this band with other HF-auto. This includes automobile security systems, other wireless devices, noise and other sources, such as microwave.
To meet this challenge, Bluetooth employs a fast frequency hopping system and therefore uses shorter packets than other standards of the ISM band. This contributes to the Bluetooth robust and secure.
Frequency Hopping
Frequency Hopping jump is, in principle, the frequency to frequency within the ISM-Funk band. After a Bluetooth device sends or receives a package, and the device (or devices), it is communication with Hop to another frequency before the next packet is sent. This system has three advantages:
1. Allows Bluetooth devices, all available data, the ISM band, and the transmission of a fixed frequency over a short period. This ensures that Bluetooth ISM with restrictions on the amount of transmission frequency.
2. Ensure that each defect will not be long. Each package, which fail to be objective can be again on the next frequency.
3. Provides a basis of security, it is very difficult for a listening device to predict the frequency of use of Bluetooth devices “Next”.
However, the devices should be based on the frequency is as follows. The Bluetooth specification allows these two types. First, a kind master and slave relationship between Bluetooth devices. In addition, it provides that the device uses an algorithm-specific information to calculate the frequency-hop sequence.
A Bluetooth device in the main mode with up to seven slave mode device. For each of the slaves, the master of a Bluetooth device is a unique address and the value of its own internal clock. The information is then to calculate the frequency-hop sequence.
Since the master device and each slave using the same algorithm with the same first entry, the device is more often the next they have agreed.
In lieu of the cable technology, it is no wonder that Bluetooth devices are batteries, such as wireless mouse batteries and mobile phones. The conservation of power, most devices with low power consumption. This helps Bluetooth devices offer a range of approximately 5 – 10 meters.
This area is wide enough for wireless communications, but close enough to avoid too much energy from the power source of the device.
