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1. In the end , implementation of if digital receiver unit of tdrss user transponder by the method of fpga and dsp cooperation design are completed successfully , which leads to good ds - ss if receiver design for the signal whose carrier frequency is 3mhz , pseudorandom code rate is 3mchips / s , data rate is 10kbps , frequency offset is no more 1khz , and modulation mode is bpsk
   最后，完成了該中頻數(shù)字接收機設(shè)計，并對其進行調(diào)試和測試。測試結(jié)果表明，該接收機能對載頻為3mhz ，頻偏不大于1khz ，偽隨機碼速率為3mchips / s ，信息碼速率為10kbps ， bpsk調(diào)制的直接序列擴頻中頻信號進行接收，基本滿足設(shè)計要求。
2. Abstract : by comparing the channel capacities hetwem orthogonal space - time block coding and multi - antenna array system over rayleigh fading channel , some capacity loss for orthogonal space - time block coding is obtained , which is a function of the code rate , the rank of channel matrix and the number of transmitter and receive antennas , although the system of orthogonal space - time block codes is simple and easy to implemented . if is also shown that there is no capacity loss only if both the code rate and the channel matrix rank are all one
   文摘:在研究瑞利衰落條件下正交空時分組編碼信道容量的基礎(chǔ)上，將其與多發(fā)送多接收天線系統(tǒng)的信道容量進行了比較.比較結(jié)果表明，正交空時分組碼雖編碼簡單，易于實現(xiàn)，但在信道容量方面存在較大的損失，損失的程度與編碼碼率、信道矩陣的秩及收發(fā)天線數(shù)等因素有關(guān).進一步研究表明只有當編碼碼率和信道矩陣的秩都為1時，才沒有信道容量的損失
3. One important feature of radio signals ’ is that the signals are easy to catch and to disturb . in order to disturb the radio signals , parameters , including code rate , modulation , protocol , protection methods and channel coding , about satellite ’ s signals should be known . so , it is possible to receive the data from satellites and obtain lots of information from it , and even to destroy the undesired information
   衛(wèi)星通信系統(tǒng)的遙控遙測信息都是通過無線信道傳遞,而無線電信號的一個很重要的特性就是發(fā)射易被接收、易被干擾,實現(xiàn)干擾的前提是對衛(wèi)星信號參數(shù)的極大了解,這包括明確信號的碼速率、調(diào)制方式、所用協(xié)議、保密措施及信道編碼等,因此,通過接收衛(wèi)星數(shù)據(jù)以獲取大量的未知信息,甚至破壞掉對己的不利信息就成為可能。
4. Optical multi ? wavelength networks have attracted much research interest recently and have been developing quickly due to their large bandwidth , their transparence of transmission code rate , data format and mode of modulation , their excellent possibility to upgrade , their simple and feasible management and powerful existence
   其巨大的傳輸容量和對傳輸碼事、數(shù)據(jù)格式及調(diào)制方式具有的透明性，良好的可擴展性，網(wǎng)絡(luò)運行和管理的簡單易行，強大的生存性使其發(fā)展越來越迅速，成為當今的研究熱點。
5. Ds signal is twice modulated with the rapid pseudorandom noise sequence and the carrier . so it appears cyclostationary . in the field of spectral correlation , ds signals appears its characteristic as fallows : for the amplitude of spectral correlation , the information of carrier frequency and pn code rate are contained on the spectrum frequency equal to zero sheet , and also the pn code rate is contained on the sheet of spectrum frequency equal to carrier frequency ; for the phase of spectral correlation , the information of carrier initial phase is contained on the sheet of cyclic frequency equal to double carrier frequency
   Ds信號是經(jīng)過高速偽隨機序列和正弦載波二次調(diào)制的寬帶信號,因此具有周期平穩(wěn)特性,它在譜相關(guān)域表現(xiàn)為:幅頻特性在譜頻率等于零截面切片上包含了載頻和偽碼速率信息特征,在譜頻率等于載頻截面切片上包含了偽碼速率信息特征;相頻特性在循環(huán)頻率等于兩倍載頻截面切片上包含了載波初相信息特征。