Bluetooth devices typically operate at a 2.4GHz license-free, globally available ISM radio frequency. The benefits of this band include all-world availability and compatibility. Disadvantages However, to do this, the devices must share their band with other HF emitters. This includes, other noise sources (such as microwaves), automotive security systems and other wireless devices.
To overcome this challenge, Bluetooth takes a high-speed frequency hopping method, packets are shorter than other standards in the ISM band. This scheme helps to make Bluetooth communication more robust and secure.
Frequency hopping
Frequency hopping basically jumps out of frequency. to frequencies within the ISM radio band. Rear Bluetooth devices send and receive packets. It also communicates with one or more devices. Jump to another frequency before the next packet arrives I posted. This scheme has three advantages:
1. Allow the Bluetooth device to use all available ISM bands in the short term, but never transmit from a fixed frequency. This helps to guarantee that Bluetooth complies with the ISM limits. transmission amount per frequency.
2. Ensure that there is no interference. It will last a long time. Packages that do not arrive safely can be resent to that destination frequency.
3. provides the following basic levels of security: Listening devices are very difficult to predict the frequency used by Bluetooth devices.
However, the connected device must agree to this. How often to use it next? specification Bluetooth guarantees this in two ways. First, it defines the master-slave type relationship between Bluetooth devices. Then specify the algorithm. However, it uses device-specific information. calculation of frequency hopping sequences.
Bluetooth devices that operate in master mode In Slave mode, it can communicate with up to 7 configured devices. For each of the master slaves, Bluetooth devices broadcast their own address and the value of their own internal clock. Or the information sent will be used in the calculation of the frequency hopping sequence.
Slave device and master device Devices use the same algorithm with the same initial input, connected devices always arrive at the next agreed-upon frequency.
As an alternative to cable technology, are Bluetooth devices usually battery-powered? Yes, powered like a wireless mouse or battery-powered cell phone. Most devices to save electricity operate on low power. This helps to conserve the power.
The range of the device is about 5–10 meters. This range is sufficient for wireless communication. But close enough not to draw too much current from the device power supply.
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