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数字下变频器(DDC,Digital Down Converter)是GSM-R直放站的重要组成部分,它将高速采样的数字中频信号下变频到基带,然后进行抽取,低通滤波。利用FPGA的芯片特性以及先进的软件分析和实现工具,实现了基于FPGA的数字下变频,重点研究了数字下变频器的数控振荡器NCO和多级滤波器的原理和硬件设计仿真,通过FPGA芯片Virtex-4XC4VSX35设计实现了适用于GSM-R直放站的数字下变频器,并对其进行了硬件仿真与验证,结果表明提出的方案正确可行,在工程应用中具有一定的参考价值。 相似文献
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本文简要介绍了传统模拟接收机与数字式接收机在中音频处理方面的区别以及数字式接收机中的中音频处理原理,以Harris公司的HSP=50016数字下变频器(简称DDC)为例,重点介绍了数字下变频器的工作原理和应用。 相似文献
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介绍了应用于数字波束形成天线的数字下变频器的基本结构,描述了利用FPGA设计数字下变频器的原理和方法;分析了实现数控振荡器、数字滤波器等关键组成部分的软件算法及性能,并给出了相应的MATLAB算法仿真结果。 相似文献
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中频数字接收部分是整个雷达和侦察设备的关键组成部分.基于雷达和侦察的数字接收技术包括窄带雷达处理和宽带侦察处理两部分.其中窄带处理包括幅相校正、窄带数字波束形成(DBF)和数字下变频部分,宽带处理包括数字信道化和宽带DBF部分.工程实现中,宽窄带处理在同一片板卡中实现,这样有利于设计和节约成本.最后,实验结果表明了该设计技术的正确性. 相似文献
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介绍一种用FPGA实现的中频数字化接收机数字下变频器,重点介绍了数字下变频器原理、能够降低运算工作量的多相滤波处理结构和分布式算法,给出了设计应用的实例。 相似文献
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低功率业余无线电收发信机是业余无线电爱好者们急需的低功率通信设备.本文介绍了一种低功率SSB收发信机的设计方法及其工作原理.该收发信机提供15 m和20 m两个波段,利用芯片MC1596实现SSB信号的产生及检波,利用芯片NE602完成混频,固定中频为9 MHz.该机体积小、重量轻、成本低、性能好,在低功率业务无线电通信领域中,具有较高的实用价值和广阔的应用前景. 相似文献
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The article presents a new method of SSB modulation which ensures maximum compatibility with AM reception. Theoretically ideal compatibility with AM receivers and theoretically ideal absence of out-of-band radiation are reached by means of application of an envelope with an infinite spectrum. It is shown that the finiteness of the spectrum of the radio signal is ensured as a consequence of the infinity of the spectrum of the envelope. The spectrum width of the proposed radio signal is equal to the spectrum width of the common SSB radio signal. Theoretical inferences are confirmed by the results of experimental tests. The proposed radio signal can be received by common home AM receivers and no other special receivers are necessary. Application of the proposed method of transmission in broadcasting makes it possible to speed up the introduction of SSB broadcasting because the broadcasters will not risk losing their audience and the listeners will not be forced to buy new receivers 相似文献
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《Vehicular Technology, IEEE Transactions on》1986,35(1):22-29
A real zero single sideband (RZ SSB) transceiver is newly proposed for mobile radio services. The necessary transmission bandwidth of RZ SSB is similar to that of a conventional SSB. In this new transceiver, an amplitude limiter, which can remove the amplitude impairment, can be used without degrading the quality of detected output signals in the receiver. Furthermore, since RZ SSB signals possess FM-like characteristics, they can be demodulated with frequency detection as well as product detection. 相似文献
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High speed modems are a means for implementing early 100 percent digital connectivity in the transition to total digital networks. The system parameters for high speed data transmission over FM and SSB microwave radio are calculated. It is shown that radio fading is not necessarily a controlling factor. Other impairments such as noise, level, and phase transients are experienced on long terrestrial circuits. The setup for field measurements and results are presented. Technical and economic network criteria are presented that led to the decision to deploy 1.544 Mbit/s modems on analog microwave radio. 相似文献
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《Vehicular Technology, IEEE Transactions on》1983,32(1):106-120
A technique is described, feedforward signal regeneration (FFSR), to combat the effects of multipath propagation on VHF and UHF pilot tone single sideband (SSB) mobile radio systems. Unlike feedforward automatic gain control (FFAGC), FFSR suppresses both the random amplitude and phase fluctuations in the received signal. Extensive laboratory and field tests have shown that the operation of SSB at UHF frequencies is a viable proposition for both speech and data communication. 相似文献
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数字下变频技术是软件无线电的核心技术之一。本文首先介绍了DDC的组成结构,然后详细分析了DDC各功能模块的工作原理,通过Modelsim完成了DDC其主要模块的仿真和调试,并进行初步系统级验证。在仿真的基础上使用了FPGA开发系统,实测了DDC的性能。 相似文献