rding to the Bluetooth frequency-hop- ping protocol. The blocks in Figure 5.2-17 are general and Center frequency Radiated power various transmitter and receiver configurations are (MHz) (mean EIRP) adopted by different manufacturers. The Gaussian low- (dBm) pass filter block before the modulator, for example, may Every 20 MHz from be implemented digitally as part of a complex signal I/Q 5180 to 5320 modulation unit or it may be a discrete element filter whose output is applied to the frequency control line of Every 20 MHz from a VCO. Similarly, the receiver may be one of several 5500 to 5680 types. If a superheterodyne configuration is chosen, the filter at the output of the downconverter will be CHAPTER 5.2 Short-range wireless applications and technologies Figure 5.2-16 Bluetooth scatternet. a bandpass type. A direct conversion receiver will use low in Table 5.2-5. A transmission burst may occur within pass filters in complex I and Q outputs of the down- a duration of one, three, or five consecutive slots on one converter. While different manufacturers employ a vari- hop channel. As mentioned, transmissions are always ety of methods to implement the Bluetooth radio, all between the piconet master and a slave, or several slaves must comply with the same strictly defined Bluetooth in the case of a broadcast, or point-to-multipoint trans- specification, and therefore the actual configuration used mission. All slaves in the piconet have an internal timer in a particular chipset should be of little concern to the synchronized to the master device timer, and the state of end user. this timer determines the transmission hop frequency of The Bluetooth protocol has a fixed-time slot of 625 the master and that of the response of a designated slave. microseconds, which is the inverse of the hop rate given Figure 5.2-18 shows a sequence of transmissions between a master and two slaves. Slots are numbered according to the state, or phase, of the master clock, which is copied to each slave when it joins the piconet. Note th