- Wireless systems operating in the 2.4 GHz ISM frequency band and sharing the same environment in an industrial environment are likely to interfere with each other due to simultaneous operation of multiple radios. Bluetooth radio system uses the frequency hopping spread-spectrum (FHSS) and time division duplex (TDD) for transmitting and receiving the packets at 79 different channels at 1,600 hops per/sec in this ISM band. It transmits the packets with a slot time of 625sec on pseudo-randomly selected channel of 1MHz bandwidth. The communicating Bluetooth devices within one network (Piconet) must be properly synchronized so that they can hop together from channel to channel; it is done by using the same channel set as well as the same hopping sequence within that channel set along with the time synchronization within the hopping sequence. The frequency interference (packet collision) between different Bluetooth devices can occur if different Piconets are running in a certain domain at ...