Bluetooth devices will usually operate at 2.4 GHZ within the license free, globally obtainable ISM radio band. The benefit to this band consists of worldwide availability and compatibility. A disadvantage to this nevertheless, is that the devices ought to share this band with other RF emitters. This consists of automobile security systems, other wireless devices, and other noise sources, for instance microwaves.
To overcome this challenge, Bluetooth employs a fast frequency hopping scheme and for that reason uses shorter packets than other standards within the ISM band. This scheme helps to create Bluetooth communication a lot more robust and much more secure.
Frequency hopping Frequency hopping is basically jumping from frequency to frequency within the ISM radio band. After a bluetooth device sends or receives a packet, it and the device (or devices) it's communicating with hop to an additional frequency just before the next packet is sent. This scheme offers 3 benefits: 1. Enables Bluetooth devices to make use of the entirety of the available ISM band, although by no means transmitting from a fixed frequency for additional than a short time period. This helps insure that Bluetooth conforms to the ISM restrictions on the transmission quantity per frequency. 2. Ensures that any interference won't last long. Any packet that does not arrive safely to its destination might be resent to the next frequency. 3. Supplies a base level of security as it is pretty difficult for an eavesdropping device to predict which frequency the Bluetooth devices will use next.
The connected devices nevertheless, need to agree upon the frequency they will use next. The specification in Bluetooth ensures this in two methods. 1st, it defines a master and slave type relationship between bluetooth devices. Next, it specifies an algorithm that uses device specific info when calculating the frequency hop sequences.
A Bluetooth device that operates in master mode can communicate with up to seven devices which are set in slave mode. To each of the slaves, the master Bluetooth device will send its own unique address and also the value of its own internal clock. The details sent is then utilized to calculate the frequency hop sequences.
Due to the fact the master device and every of the slave devices use the same algorithm with the identical initial input, the connected devices will generally arrive together at the next frequency that they have agreed upon.
As a replacement for cable technology, it is no wonder that Bluetooth devices are generally battery powered, like wireless mice and battery powered cell phones. To conserve the power, most devices operate in low power. This helps to give Bluetooth devices a range of around 5 - 10 meters.
This range is far sufficient for wireless communication but close sufficient to steer clear of drawing too a lot power from the power source of the device.
Author Resource:
The InterBluetooth.co.uk site gives information on bluetooth and bluetooth vs wifi .
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