毕业论文外翻译-移动通信系统的解调技术.docVIP

1 原文 In recent years,our moble communication service swift and violent development,penetrated into social life each aspect,facing the motion user group continually growth and new service emerging one after another incessantly,the mobile communication system must adapt promptly even in advance in the market demand step.But took of a digital modulating technology modulating technique mobile communication system important guarantee.The digital modulation demodulation technolagy holds the extremely important status in the digital communication,the commonly used digital modulation includes:Frequency shift keying(FSK)and phase_shift keying (PSK)and so on. At present has used in the mobile communication system the modulating technology modulating technique being possible to divide into two big kinds:The linear modulating technology and the permanent enveloping modulating technology modulating technique linear modulation techology mainly has:PSK-BPSK、QPSKOQPSK/4-QPSK、QAM、16QAM、64QAM、256QAM.the permanent envelope modulating technology modulating technique mainly has:MSK TFM GMSK. The article in view of the three kind of basicial modulation demodulation technology has carried on the detailed simulation and the analysis,obviously,chooses one kind of modulatinf technology modulating technique is determined according to the channel characteristic and the application.The power efficiency and the frequency spwcturm effciency cannot be satisfactory to both sides generally uneven America.The high frequency specteum efficiency needs to sacrifice certain power effciency to obtain;Similarly,the high power efficiency also needs to sacrifice certain frequency specteum sfficiency.Along with the modulation technique in the unceasing development, the new modulating technology modulating technique mighe being the better frequency spectrum efficiency and the higher power efficiency. FSK and PSK in the numeral moible communication the find application,in which FSk already obtained the use in