Bluetooth operates in the 2.4 GHz ISM band, specifically between 2.402 GHz and 2.480 GHz.
Here's a breakdown:
- Frequency Range: The core operational range for Bluetooth is 2.402 GHz to 2.480 GHz.
- ISM Band: This range falls within the globally available Industrial, Scientific, and Medical (ISM) 2.4 GHz radio frequency band. This band is unlicensed, allowing for widespread use but still subject to regulations.
- Guard Bands: Bluetooth specifications include guard bands to minimize interference with other technologies. These bands extend the total frequency range to 2.400 GHz to 2.4835 GHz, including a 2 MHz guard band at the lower end and a 3.5 MHz guard band at the upper end.
- Global Usage: The 2.4 GHz ISM band's near-universal availability makes Bluetooth a globally interoperable technology.
- FHSS (Frequency-Hopping Spread Spectrum): Bluetooth utilizes FHSS to further reduce interference and improve security. This involves rapidly switching between different frequencies within the 2.402 GHz to 2.480 GHz range. The number of channels used depends on the Bluetooth version and regulatory domain, but it typically uses 79 channels spaced 1 MHz apart.
In summary, Bluetooth operates within a specific slice of the 2.4 GHz ISM band, leveraging frequency-hopping techniques to coexist with other wireless technologies.
