●●● ●●●● ●●●●心 ●●●● ●●●●0 Comparing with transmitting baseband signal ●●●● ●●●● ●● directly,to transmit data by modulating a higher frequency carrier wave has the effect on: .1controlling the radiated frequency spectrum. 控制辐射频谱 2more efficient use of the allocated RF bandwidth. 更有效利用射频带宽 3flexibility in accommodating different baseband signal formats.便于采用不同的基带信号格式 7
Comparing with transmitting baseband signal directly, to transmit data by modulating a higher frequency carrier wave has the effect on: ①controlling the radiated frequency spectrum. 控制辐射频谱 ②more efficient use of the allocated RF bandwidth. 更有效利用射频带宽 ③flexibility in accommodating different baseband signal formats.便于采用不同的基带信号格式 7
●●● ●●●● ●●●● ●●●0 ●●●● V(t)=Acos(ot+0) ●●●● ●●●● Amplitude Frequency Phase 幅度 频率 相位 AM FM PM 调幅 调频 调相 Analog modulation (vary continuously) 模拟调制（连续变化） Digital modulation (change in discrete steps) 数字调制（离散阶跃变化） 8
Amplitude Frequency Phase 幅度 频率 相位 Vt A t ( ) cos( ) AM FM PM 调幅 调频 调相 Analog modulation (vary continuously) 模拟调制 (连续变化 ) Digital modulation (change in discrete steps) 数字调制（离散阶跃变化） 8
●● ●●●● ●●●●● In contrast to analog modulation, ●●●● ●●●●0 ●●●● digital modulation has: ●●●色 ●● 与模拟调制相比，数字调制有下面的好处 1more efficient use of the radio spectrum. 更有效利用射频频谱 2usually requires less power.CDMA 通常所需的功率小 3over a fading communications channel. 克服通信信道的衰落 4more compatible with the use of error correcting codes.便于与纠错兼容 Need wider frequency bands. 9
①more efficient use of the radio spectrum. 更有效利用射频频谱 ②usually requires less power. CDMA 通常所需的功率小 ③over a fading communications channel. 克服通信信道的衰落 ④more compatible with the use of error correcting codes.便于与纠错兼容 Need wider frequency bands. In contrast to analog modulation, digital modulation has: 与模拟调制相比，数字调制有下面的好处 9
●●● ●●●● ●●●● ●●●0 ●●●●0 ●●●● ●●●● ●● §9.1 Analog Modulation模拟调制 §9.2 Binary Digital Modulation二进制数字调制 9.3 Error Probabilities for Binary Modulation 二进制调制的出错概率 S 9.4 Effect of Rayleigh Fading on Bit Error Rats 瑞利衰落对误码率的影响 §9.5M-ary Digital ModulationMa维的数字调制 10
§9.1 Analog Modulation模拟调制 §9.2 Binary Digital Modulation二进制数字调制 §9.3 Error Probabilities for Binary Modulation 二进制调制的出错概率 §9.4 Effect of Rayleigh Fading on Bit Error Rats 瑞利衰落对误码率的影响 §9.5 M-ary Digital ModulationM维的数字调制 10
●●● ●●●● 9.1 Analog Modulation ●●●● ●●●● ●●●● ●●●● Basic analog modulation: ●●● ● ● AM(SSB,DSB),FM,PM l.Signal-Sideband Modulation单边带调制 2.DSB-Suppressed Carrier Modulation双边带抑制载波调制 3.DSB-Larger Carrier Modulation双边带大载波调制 4.Envelope Detection of DSB-LC Modulation 双边带大载波调制包络检波 5.Frequency Modulation(FM)频率调制 11
§9.1 Analog Modulation Basic analog modulation: AM (SSB, DSB), FM, PM 1. Signal-Sideband Modulation单边带调制 2. DSB-Suppressed Carrier Modulation双边带抑制载波调制 3. DSB-Larger Carrier Modulation双边带大载波调制 4. Envelope Detection of DSB-LC Modulation 双边带大载波调制包络检波 5. Frequency Modulation (FM)频率调制 11