EE4512 Analog and Digital Communications Chapter 3Chapter 3Chapter 3Digital Baseband Modulation Digital Baseband Modulation TechniquesTechniquesEE4512 Analog and Digital Communications Chapter 3Chapter 3Chapter 3Digital Baseband Modulation Digital Baseband Modulation TechniquesTechniques••Goals in Communication SystemGoals in Communication SystemDesignDesign••Pages 75Pages 75--7676EE4512 Analog and Digital Communications Chapter 3••Communication System DesignCommunication System DesignSourceSourceandandTransmitterTransmitterChannelChannelNoiseNoiseReceiverReceiverAn information An information sourcesource(voice, music, video, text, signals (voice, music, video, text, signals or images) is or images) is modulatedmodulatedin the in the transmitter transmitter ..SVU Figure 2.1SVU Figure 2.1EE4512 Analog and Digital Communications Chapter 3••Communication System DesignCommunication System DesignSourceSourceandandTransmitterTransmitterChannelChannelNoiseNoiseReceiverReceiverThe output of the transmitter is inputted to the physical The output of the transmitter is inputted to the physical transmission mediumtransmission medium(wires, fiber optics, wireless or (wires, fiber optics, wireless or acoustic) as a acoustic) as a channelchannelwith additive with additive noisenoise..SVU Figure 2.1SVU Figure 2.1EE4512 Analog and Digital Communications Chapter 3••Communication System DesignCommunication System DesignSourceSourceandandTransmitterTransmitterChannelChannelNoiseNoiseReceiverReceiverThe output of the channel is inputted to the The output of the channel is inputted to the receiverreceiverwhich attempts to which attempts to demodulatedemodulatethe signal and the signal and recover recover the the data.data.SVU Figure 2.1SVU Figure 2.1EE4512 Analog and Digital Communications Chapter 3Chapter 2Chapter 2Baseband Modulation and Baseband Modulation and DemodulationDemodulation••Rectangular Pulse AmplitudeRectangular Pulse AmplitudeModulation (PAM)Modulation (PAM)••Pages 60Pages 60--6464EE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)SVU Figure 2.1SVU Figure 2.1Token 0Token 0Token 1Token 1EE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)PseudoPseudo--noise Sequence generator (Token 0) simulates a noise Sequence generator (Token 0) simulates a binary information source, bit rate rbinary information source, bit rate rbb= 1 kb/sec= 1 kb/secEE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)Gaussian Noise generator (Token 1) provides a random Gaussian Noise generator (Token 1) provides a random noise source, mean = 0 V, standard deviation noise source, mean = 0 V, standard deviation σσ= 0.1 V= 0.1 VEE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)SVU Figure 2.1SVU Figure 2.1Sink 9Sink 9Sink 8Sink 8EE4512 Analog and Digital Communications Chapter 3••Output of Binary PAM Transmitter (Token 1, Sink 9)Output of Binary PAM Transmitter (Token 1, Sink 9)•Input of Binary PAM Receiver with AWGN (Token 3, Sink 8)Input of Binary PAM Receiver with AWGN (Token 3, Sink 8)EE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)SVU Figure 2.1SVU Figure 2.1Token 4Token 4Token 2Token 2Token 5Token 5EE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)SystemVue SystemVue Figure 2.1Figure 2.1System Time with a time spacing System Time with a time spacing of 20 of 20 µµsecsecEE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)Pulse Train (Token 2) outputs a narrow (20 Pulse Train (Token 2) outputs a narrow (20 µµsec) sec) sampling control signal at a 1 kHz rate at Tsampling control signal at a 1 kHz rate at Tb b / 2 (180/ 2 (180ºº))System Time specificationEE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)Sample and Hold (Token 4) uses theSample and Hold (Token 4) uses thecontrol signal (180control signal (180ººphase shift)phase shift)to sample the receiver input signal at Tto sample the receiver input signal at Tb b / 2/ 2EE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)Analog Comparator (Token 5) removes the uneven output Analog Comparator (Token 5) removes the uneven output signal levelsignal levelEE4512 Analog and Digital Communications Chapter 3••Rectangular Pulse Amplitude Modulation (PAM)Rectangular Pulse Amplitude Modulation (PAM)SVU Figure 2.1SVU Figure 2.1Sink 6Sink 6Sink 7Sink 7EE4512 Analog and Digital Communications Chapter 3••Input of Binary PAM Receiver with AWGN (Token 3, Sink 8)Input of Binary PAM Receiver with AWGN (Token 3, Sink 8)•Output of Sample and Hold (Token 4, Sink 7)Output of Sample and Hold (Token 4, Sink 7)TTbb/ 2/ 2delaydelayEE4512 Analog and Digital Communications Chapter 3••Output of Sample and Hold (Token 4, Sink 7)Output of Sample and Hold (Token 4, Sink 7)•Output of Analog Comparator (Token 5, Sink 6)Output of Analog Comparator (Token 5, Sink 6)TTbb/ 2/ 2delaydelayTTbb/ 2/ 2delaydelayEE4512 Analog and Digital Communications Chapter 3Chapter 3Chapter 3Digital Baseband Modulation Digital Baseband Modulation TechniquesTechniques••Baseband Modulation UsingBaseband Modulation UsingRectangular Pulses and BinaryRectangular Pulses and BinaryPulse Amplitude ModulationPulse Amplitude Modulation••PagesPages7676--8888EE4512 Analog and Digital Communications Chapter 3••PAM generation of data sequence 0 or 1PAM generation of data sequence 0 or 100011011SVU for S&M Figure 3SVU for S&M Figure 3--55EE4512 Analog and Digital Communications Chapter 3••PAM generation of data sequence 00, 01, 10 and 11PAM generation of data sequence