共查询到19条相似文献,搜索用时 122 毫秒
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概述了模拟信号数字化转换技术的现状和中频信号数字化技术的重要性,主要介绍了中频信号数字化传输系统的实现原理、关键芯片和典型应用电路,并提供了对电路主要环节链路噪声的优化控制方法,可以给初始参与模拟中频数字化设计的人员提供一定的技术参考。 相似文献
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本文主要介绍一种中频信号数字化传输设备.该设备将用户的中频模拟数据信号经数字化处理后通过光纤进行远距离传输,并在接收端还原成模拟数据信号和用户的终端设备进行通信.本套设备克服了传统的模拟设备在传输过程中接收灵敏度低、成本高、动态增益小、不易控制等缺点. 相似文献
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大规模集成电路的发展使得数字中频采样收发机的实现成为现实。本文使用宽带中频数字化方案,利用FPGA中的IP核把经过AD转换后的中频信号通过数字下变频处理为基带信号,并利用Matlab中的Dspbuilder提供的IP核得到了总体的仿真结果。该接收系统用于WCDMA移动通信网络的基站体系中,能很好地实现手机信号覆盖和传输。 相似文献
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文中结合雷达中频信号数字化课题的具体要求,在讨论数字中频的理论算法和工程实现方案的基础上,设计了基于软件无线电思想的雷达中频数字化硬件平台。针对软件无线电的中频数字化技术进行探讨,深入研究了有关信号采样和数字正交的理论,探讨了实现数字正交采样相干检波的高精度算法,设计了基于软件无线电思想的中频数字化硬件系统,主要包括信号采集电路设计、中频数字化电路设计、逻辑控制电路设计和系统自检电路设计四个部分。此外,本方案还可在无雷达回波数据的情况下进行系统自检,大大提高了系统的可调试性和可靠性。 相似文献
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本文主要从数字化光纤传输系统发射端设备和接收端设备的组建、数字光端机的选用、光缆传输线路的设计、一次切换和二次切换信号传输链路应用情况、系统安全可靠性保障、系统技术维护等方面,论述和总结了扬州电视台现场直播信号数字化光纤传输系统组建与应用情况。 相似文献
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中频脉中压缩信号数字化直接产生技术研究 总被引:2,自引:0,他引:2
该文提出了一种脉冲压缩中频信号数字化产生方法及硬件实现方案,对其中的一些关键问题做出了定量分析;在此基础上完成了一套波形产生器,可产生6种中频15MHz、带宽1MHz、时宽等于或小于300s的线性调频、非线性调频信号。测试表明其谐波与杂散均优于-68dB,完全达到工程应用要求。 相似文献
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We have developed a CMOS A/D converter for I/Q demodulation with an analog mirror signal suppression filter in the sampling unit. The circuit directly converts a modulated 30 MHz IF signal to digitized I and Q values in the base band with an accuracy of more than 10 b. The output data rate is 2 MHz and the power consumption is 270 mW. By placing the I/Q split mirror suppression filter on the analog side, we can get a highly integrated system solution for a coherent receiver. The circuit uses multiple sampling, that gives the input values to the filter. The sizes of the sampling capacitors determine the coefficients for the filter multiplications. The sampled charges are then added in order to get the filter additions. This total charge is then converted to digital form in a single conversion. By requiring the filter to block DC, the filter subtraction becomes a part of the active offset reduction using correlated double sampling. Careful layout and very simple circuit solutions make the design possible 相似文献
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针对宽带雷达线性调频信号产生,采用FPGA电路和宽带DAC电路直接产生50 MHz~550 MHz 的线性调频中频信号。将中频信号上变频到2 GHz~2. 5 GHz 的射频频段,再经过2 倍频获得4 GHz~5 GHz的宽频带线性调频信号。为进一步提高射频输出信号的幅度/相位特性,采用幅/相预失真校准方法,并精心设计信号产生系统的中频电路和射频电路,进行了实验研究与分析。对实际系统的测试结果表明,系统产生LFM信号的带外杂散优于-55 dB,带内起伏小于依2 dB,且系统稳定、可靠。 相似文献
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基于无线局域网(Wireless Local Area Networks,WLAN)的正交频分复用(Orthogonal Frequency DivisionMultiplexing,OFDM)信号,提出了一种低成本、小体积的接收机设计方案。采用零中频下变频技术,简化了接收机电路结构,并且通过对影响接收性能关键技术指标的分析,证明该设计能够满足OFDM信号接收解调要求。介绍了一种宽带全直流耦合驱动电路的设计方法,为下变频电路和采样电路间的提供可靠连接,解决含直流宽带信号传输中普遍存在的直流漂移和增益稳定问题。通过实际测试结果验证了接收方案的正确性和工程实用性。 相似文献
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《Solid-State Circuits, IEEE Journal of》1968,3(4):408-416
A direct-coupled monolithic IF amplifier that incorporates an active gain control stage and exhibits a power gain of 50 dB and an AGC range of 60 dB at 50 MHz is described. This circuit has negligible change in either input or output admittance, and has excellent signal linearity over the full range of gain control. Experimental and theoretical analyses are made of the large signal response, stability, available gain, and noise behavior of the circuit. An application to color television is discussed in which the functions of the 45-MHz IF amplifier and the dc-AGC circuitry are fabricated on a single die. 相似文献
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A multichannel coherent subcarrier multiplexing (SCM) system using standard distributed-feedback lasers is discussed. A simple phase noise canceling circuit yields excellent quality FM video transmission (SNR=56 dB), even though the 50-MHz IF linewidth exceeds the 30-MHz signal bandwidth 相似文献
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Susheel K. Verma Girja Shankar Deepak Singh 《Journal of Infrared, Millimeter and Terahertz Waves》1994,15(3):559-566
A balanced upconverter circuit has been developed in planar transmission line configuration using NEC GaAs beam lead Schottky barrier diodes. RF power output of +1.6 dBm SSB is obtained at Ka-band when up converter is driven by +17 dBm IF and +20 dBm LO signal. 相似文献
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介绍了一种GPS中频信号生成器的设计,利用了Xilinx公司的microblaze软核技术,生成器的核心部分在一块FPGA内部实现.降低了电路设计的复杂性以及实现成本,并且使得系统更具灵活性和扩展性.将详细描述生成器核心部分中microblaze系统的搭建以及关键逻辑电路的设计,最后给出生成器输出中频信号的频谱分析结果,并使用GPS接收机对上变频后的信号进行了接收测试. 相似文献
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This paper considers the use of time compression multiplexing (TCM) for telephone loop communications. The analysis treats TCM transmission degradations in general, and applies the results to telephone speech transmission. To gain an understanding of the nature of TCM degradations, transmission through a linear, time invariant network and demultiplexing is considered. The channel signals are then assumed to be wide-sense stationary random processes, and expressions for the spectral properties of the TCM distortion and interchannel crosstalk are determined. To accurately evaluate the performance of a TCM system, a practical and economical equalizer is proposed. It is designed to meet speech transmission requirements for the telephone loop plant. A worst case application is chosen to evaluate the system performance. The evaluation of the TCM transmission performance utilizes both the random signal model and a computer simulation using digitized speech. The random signal analysis shows that the spectra of the distortion and crosstalk are significant for human speech. Results of the digitized speech simulation demonstrate that the subjective effect of the signal distortion is not severe, but the crosstalk is somewhat intelligible and more severe than expected. 相似文献