Bluetooth is a short distance wireless communication protocol:
10m (30 ft) for class 2 or 3 modules (0dBm or 1mW for class 3), 100m (300 ft) for class 1 modules (20dBm or 100mW).

Bluetooth relies on a radio link in the ISM 2,45GHz band. However, this radio link can be subject to great stress. In addition to the traditional fading problems (multiple tracks and absorption by water), much interference can be caused by other products on the ISM band (such as microwave ovens, products using the 802.11b (WiFi) protocol, or other unsynchronized Bluetooth products). To increase the strength of the radio link, frequency-hopping technology is used on the 79 available channels, with 1600 jumps per second. Each channel has a width of 1MHz. These frequency jumps enable limited interference. In addition, since each packet has its own channel, if a packet is badly transmitted, it will be re-transmitted on another channel.
The modulation used is a GFSK (Gaussian Frequency Shift Keying) with a modulation speed of 1Mbit/s.

For further information about Bluetooth Wireless Technology,
please download bluetooth_protocol.pdf (125ko)