現(xiàn)代通信原理課件chapterone(文件)
【正文】 he digital receiver. And showed that if the rate of information R(bits/s) was less than C,the BER would approach zero. 33 In analog system, the optimum system might be defined as the one that achieves the largest signaltonoise ratio at the receiver output, subject to design constraints such as channel bandwidth and transmitted power. Nyquist showed that if a pulse represents one bit of data, noninterfering pulse could be sent over a channel no faster than 2B pulses/s, where B is the channel bandwidth in hertz. That is now known as the dimensionality theorem. Channel Capacity 34 Example SA13: A puter user plans to buy a higherspeed modem for sending data over his or her analog telephone line. The telephone line has a signaltonoise ratio(SNR) of 25dB and passes audio frequencies over the range, from 300 to 3200Hz, Calculate the maximum data rate that could be sent over the telephone line when there are on errors at the receiving end. Solution: In the term of a power ratio, the SNR=10(25/10)=, the bandwidth is B=3200300= 2900 Hz， we get: Channel Capacity ? ? sbi t sNSBC /24097)(l og29001l og22 ????????? ??Problem: Can a And a 35 Problems: , , , , Reading: page 12, 167。 (4) Waveforms Introduction 6 1 Jimes （ 1864） 2 Heinrich Hertz （ 1887） 3 Claude (1948) Introduction 7 Perspective of munication Wire opticfiber and works wireless 1G2G3GB3G WLAN。 mon application。 Chapter One 4 What is a munication system? Communication systems is used to transmit information. Introduction 5 Key conceptions or words (1) Information。 MIMO and MIMOOFDM, UWB, optic –wireless munication Introduction 8 What must be considered when you design a munication system? 1. Selection of the informationbearing waveform 2. Bandwidth and power of the waveform 3. Effect of system noise on the received informa
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