at Table 5.2-5 Bluetooth technical parameters master transmissions take place during even numbered Characteristic Value Comment clock phases and slave transmissions during odd num- bered phases. Transmission frequency depends on the Frequency band 2.4 to 2.483 GHz May differ in some clock phase, and if a device makes a three or five slot countries transmission (slave two in the diagram), the intermediate Frequency hopping 79 1-MHz channels May differ in some frequencies that would have been used if only single slots spread spectrum from 2402 to countries were transmitted are omitted (f4 and f5 in this case). (FHSS) 2480 MHz Note that transmissions do not take up a whole slot. Hop rate 1600 hops per Typically, a single-slot transmission burst lasts 366 mi- second croseconds, leaving 259 microseconds for changing the frequency of the synthesizer, phase locked loop settling Channel bandwidth 1 MHz 20 dB down at edges time, and for switching the transceiver between transmit Modulation Gaussian frequency and receive modes. shift keying (GFSK) There are two different types of wireless links associ- ated with a Bluetooth connection. An asynchronous Filter BT = 0.5 Gaussian Filter bandwidth connectionless link (ACL) is used for packet data transfer = 500 kHz while a synchronous connection oriented link (SCO) is primarily for voice. There are two major differences be- Nominal modulation Nominal deviation tween the two link types. When an SCO link is established index = 0.32 = 160 kHz between a master and a slave, transmissions take place on Symbol rate 1 Mbps dedicated slots with a constant interval between them. Transmitter maximum power Also, unlike an ACL link, transmitted frames are not re- peated in the case of an error in reception. Both of these Class 1 100 mW Power control conditions are necessary because voice is a continuous required real-time process whose data rate cannot be randomly Class 2 2.5 mW Must be at least 0.25 varied without affecting intelligibility. On the other hand, packet data transmission can u