tailieunhanh - Digital Communication I: Modulation and Coding Course-Lecture 7

Another source of error due to filtering effect of the system: Intersymbol. interference (ISI) The techniques to reduce ISI. Pulse shaping to achieve zero ISI at the sampling time. Equalization to combat the filtering effect of the bandpass modulation schemes used in DCS for transmitting information oer channel. MPAM, MPSK, MFSK, MQAM How to detect the transmitted information at the receiver. Coherent detection. Noncoherent detection. | Digital Communications I: Modulation and Coding Course Term 3 - 2008 Catharina Logothetis Lecture 7 Lecture 7 Last time we talked about: Another source of error due to filtering effect of the system: Inter-symbol interference (ISI) The techniques to reduce ISI Pulse shaping to achieve zero ISI at the sampling time Equalization to combat the filtering effect of the channel Lecture 7 Today, we are going to talk about: Some bandpass modulation schemes used in DCS for transmitting information over channel M-PAM, M-PSK, M-FSK, M-QAM How to detect the transmitted information at the receiver Coherent detection Non-coherent detection Lecture 7 Block diagram of a DCS Format Source encode Format Source decode Channel encode Pulse modulate Bandpass modulate Channel decode Demod. Sample Detect Channel Digital modulation Digital demodulation Lecture 7 Bandpass modulation Bandpass modulation: The process of converting a data signal to a sinusoidal waveform where its amplitude, phase or frequency, | Digital Communications I: Modulation and Coding Course Term 3 - 2008 Catharina Logothetis Lecture 7 Lecture 7 Last time we talked about: Another source of error due to filtering effect of the system: Inter-symbol interference (ISI) The techniques to reduce ISI Pulse shaping to achieve zero ISI at the sampling time Equalization to combat the filtering effect of the channel Lecture 7 Today, we are going to talk about: Some bandpass modulation schemes used in DCS for transmitting information over channel M-PAM, M-PSK, M-FSK, M-QAM How to detect the transmitted information at the receiver Coherent detection Non-coherent detection Lecture 7 Block diagram of a DCS Format Source encode Format Source decode Channel encode Pulse modulate Bandpass modulate Channel decode Demod. Sample Detect Channel Digital modulation Digital demodulation Lecture 7 Bandpass modulation Bandpass modulation: The process of converting a data signal to a sinusoidal waveform where its amplitude, phase or frequency, or a combination of them, are varied in accordance with the transmitting data. Bandpass signal: where is the baseband pulse shape with energy . We assume here (otherwise will be stated): is a rectangular pulse shape with unit energy. Gray coding is used for mapping bits to symbols. denotes average symbol energy given by Lecture 7 Demodulation and detection Demodulation: The receiver signal is converted to baseband, filtered and sampled. Detection: Sampled values are used for detection using a decision rule such as the ML detection rule. Decision circuits (ML detector) Lecture 7 Coherent detection Coherent detection requires carrier phase recovery at the receiver and hence, circuits to perform phase estimation. Sources of carrier-phase mismatch at the receiver: Propagation delay causes carrier-phase offset in the received signal. The oscillators at the receiver which generate the carrier signal, are not usually phased locked to the transmitted carrier. Lecture 7 Coherent detection .

• Điện - Điện tử
• digital communication
• multiuser communication
• multicarrier system
• adaptive equalization
• filter channel
• soure coding
• Communication systems
• Digital communication systems