GSM-R频段接收机前端设计与仿真-通信与信息系统业毕业论文.docx

AB AB STRACT ABSTRACT：GSM·R Communication system is designed for the application of the railway di百tal wireless communications，the differences between GSMGSM-R systems lies only in the frequency distribution and overlapping．GSM-R system adopts the same frequency aS the GSM network，from which the same frequency and adjacent channel interference hamper the development of GSM-R Seriously．As a private network,GSM-R system needs well signal-receiving，SO a good signal receiver plays all important part in GSM—R communication and network construction． Based on the analysis and study of previous researches and characteristics of GSM—R receiver performance and structure，in this paper a superheterodyne receiver front-end with double-conversion SOlution is put forward and simulated．In this SOlution,the signals will be processed at RF,1砒IF2nd IF,and through this procession，an excellent gain distribution can be achieved，quality of signal reception can be improved as well． In this procession，the antenna transfer the weak electromagnetic signals into electric signals，after passing the band-pass filter,the signals enter two low—noise amplifiers to be amplified,and later the enlarged signals will be sent to the two mixers for down conversion．The Primary mixer with a relatively higla IF call suppress the enantiomorphism frequency signals and make channel selection easily, and double-conversion、析nl a lower IF output facilitates the follow-up disposal．In the Paper all the key modules of the front-end are simulated．Through analysis and researching on the low-noise amplifiers，mixers and filters，combining with the basis of the principle， each module circuit of the front—end of the receiver is determined．Through the modular design of the modules and systems，reunification is achieved． When designing the low noise amplifier(LNA)，a detailed analysis of the RF amplifier noise performance and the introduction of simulation model are discussed． The compromise between the input impedance matching