subject: How Bluetooth Works [print this page] Bluetooth devices will usually operate at 2.4 GHZ in the license free, worldwide available ISM radio band. The benefit to this band includes worldwide availability and compatibility. A drawback to this is that the devices must share this band with other RF emitters. This includes car protection systems, other wireless devices, and other noise sources , for example microwaves. To triumph over this challenge, Bluetooth employs a fast frequency hopping scheme and so uses shorter packets than other standards inside the ISM band. This plan helps to make Bluetooth communication tougher and safer. Frequency hopping Frequency hopping is largely jumping from frequency to frequency in the ISM radio band. After a bluetooth device sends or receives a packet, it and the device ( or devices ) it's talking with hop to another frequency before the following packet is sent. This plan offers 3 advantages : one. Permits Bluetooth devices to use the totality of the available ISM band, while never broadcasting from a fixed frequency for at least a brief period of time. This helps insure that Bluetooth conforms to the ISM limitations on the transmission quantity per frequency. Two. Guarantees that any interference will not last long.
Any packet that doesn't arrive safely to its destination can be resent to the next frequency. Three. Offers a base amount of security as it's extremely hard for an eavesdropping device to foretell which frequency the Bluetooth devices will use next. The connected devices must agree upon the frequency they are going to use next. The blueprint in Bluetooth makes sure this in 2 ways.
First, it outlines an excellent and slave type relationship between bluetooth devices.
Next, it mentions an algorithm that uses device precise info when figuring out the frequency hop sequences. A Bluetooth device that operates in master mode can communicate with up to 7 devices that are set in slave mode.
To every one of the slaves, the master Bluetooth device will send its own unique address and the value of its own internal clock. The data sent is then used to work out the frequency hop sequences. As the master device and each one of the slave devices use the same algorithm with the same first input, the connected devices will always arrive together at the following frequency that they have agreed on.
As a replacement for wire technology, it's small wonder that Bluetooth devices are usually battery powered, like wireless mice and battery powered cell telephones. To preserve the power, most devices operate in low power. This helps to give Bluetooth devices a variety of around five - ten meters. This range is far enough for wireless communication but close enough to avoid drawing too much power from the power source of the gizmo.
