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Based on the communication network Direct3D visual simulation engine design and implementationtheVisual Simulation (Visual Simulation) is used to realize 3 d space information visualization technology, it has a realistic Simulation effect and convenient operation method, can well satisfy the new plane avionics system design requirements.This paper designs and realizes an Direct3D based on the communication network visual simulation engine.First, in this paper the characteristics of the visual simulation and the programming essentials Direct3D brief analysis of selection, and expounds the main reason for the Direct3D. Secondly, put forward the visual simulation software, the total design project of the simulation software program and the software module partition the working process of the analysis of the various modules, explore the main functions and the relations among them. And then, based on the communication network of Direct3D visual simulation is the key technology of engine are analyzed and the study, introduces solutions discrete event simulation, Direct3D resource management and animation optimization and the mouse control technology, the key technology of the method. Finally, this essay discusses the Direct3D based on the communication network visual simulation software realization method, and in a more complex switched communication network as an example, the visual simulation, and the performance of the program was tested

A Low-Cost and Low-Power CMOS Receiver Front-End for MB-OFDM Ultra-Wideband Systems要该文全文，更换别的论文，或要中英文对照都可以找我Mahim Ranjan, Member, IEEE, and Lawrence E. Larson, Fellow, IEEE0Abstract—This paper presents an RF receiver front-end for MB-OFDM-based ultra-wideband (UWB) systems. The receiver occupies only 0.35 in a 0.18 CMOS process and consists of a low-noise amplifier, downconverter and a bandpass filter. There are no on-chip inductors and the receiver requires no off-chip matching components. The measured receiver gain is 21 dB, noise figure is less than 6.6 dB, input IIP3 is 5.6 dBm, and the receiver consumes 19.5 mA from a 2.3 V supply. The receivercovers all the MB-OFDM bands from 3.1 to 8 GHz.Index Terms—CMOS, distortion, OFDM, receiver, ultra wideband, UWB.I. INTRODUCTIONULTRA-WIDEBAND (UWB)multi-band orthogonal frequency-division multiplexing (MB-OFDM) systems have been proposed as an emerging solution to wireless communicationapplications requiring high data rates (up to 480 Mb/s) over short distances. In one proposed version [1], the carrier, with a bandwidth of 528 MHz, can hop to one of 14 channels（2904+528n,n=123…14）, divided into four groups of three channels and one group of two channels. This representative time-frequency interleaving for a Group 1-only systemis depicted in Fig. 1. Design of a receiver for such a systempresents many challenges due to the wide bandwidth of the RF front-end. However, to assure the widest possible adoption, RF portions of these systems should consume little DC power and die area, and be implemented in a standard CMOS process. These last requirements argue against the use of on-chip inductors wherever possible.Since theUWBfront-end intrinsically possesses a wide bandwidth, it is open to reception of undesired narrowband signals such as 802.11 a/b/g and the recently proposedWiMAX [2] systems, as shown in Fig. 2. Although OFDM systems are less susceptible to relatively narrowband jammers, nonlinearities in the receiver can result in jammer cross-modulation with wideband input signals, resulting in reduced signal-to-noise ratio (SNR) and a degradation in system performance [3]. In addition, received wideband signals (from other UWB transmitters) can intermodulate and the resulting products can land in a desired channel. Since the system is inherently wideband, harmonic distortion of a single unwanted UWB transmitter can also produce in-band distortion products and reduce the SNR. For the system to successfully operate in such a hostile environment, the linearity specifications of the receiver need to include these distortion effects. Fig. 1. Representative time-frequency interleaving pattern of a Group 1MB-OFDM signal [1]. Fig. 2. Representative spectrum at an MB-OFDM receiver antenna.This paper describes a UWB heterodyne receiver front-end that is designed to minimize the effects of wideband jammers from a variety of undesired sources [4]. In addition, the receiver is designed to minimize silicon area, so on-chip inductors are not employed. The receiver architecture is presented in Section II. Specifications for the receiver are derived in Section III. Detailed block design is presented in Sections IV–VI. Layout and packaging of the chip is discussed in Section VII. Measured results are presented in Section VIII, followed by a conclusion in Section IX.II. RECEIVER ARCHITECTUREWhen it comes to designing a low-power and low-cost receiver, the traditional choice is a direct conversion architecture. However, a direct conversion UWBreceiver, while attractive for power consumption and simplicity of its local oscillator (LO) scheme [5], [6], has a well-known problem of time-varying DC offset and sensitivity to narrowband jammers. A DC offset at the output of the receiver can degrade the SNR of the digitized baseband signal. In addition, it can introduce second-order distortion in the baseband signal, which further degrades the SNR. A Low-Cost and Low-Power CMOS Receiver Front-End for MB-OFDM Ultra-Wideband SystemsMahim Ranjan, Member, IEEE, and Lawrence E. Larson, Fellow, IEEE0Abstract—This paper presents an RF receiver front-end for MB-OFDM-based ultra-wideband (UWB) systems. The receiver occupies only 0.35 in a 0.18 CMOS process and consists of a low-noise amplifier, downconverter and a bandpass filter. There are no on-chip inductors and the receiver requires no off-chip matching components. The measured receiver gain is 21 dB, noise figure is less than 6.6 dB, input IIP3 is 5.6 dBm, and the receiver consumes 19.5 mA from a 2.3 V supply. The receivercovers all the MB-OFDM bands from 3.1 to 8 GHz.Index Terms—CMOS, distortion, OFDM, receiver, ultra wideband, UWB.I. INTRODUCTIONULTRA-WIDEBAND (UWB)multi-band orthogonal frequency-division multiplexing (MB-OFDM) systems have been proposed as an emerging solution to wireless communicationapplications requiring high data rates (up to 480 Mb/s) over short distances. In one proposed version [1], the carrier, with a bandwidth of 528 MHz, can hop to one of 14 channels（2904+528n,n=123…14）, divided into four groups of three channels and one group of two channels. This representative time-frequency interleaving for a Group 1-only systemis depicted in Fig. 1. Design of a receiver for such a systempresents many challenges due to the wide bandwidth of the RF front-end. However, to assure the widest possible adoption, RF portions of these systems should consume little DC power and die area, and be implemented in a standard CMOS process. These last requirements argue against the use of on-chip inductors wherever possible.Since theUWBfront-end intrinsically possesses a wide bandwidth, it is open to reception of undesired narrowband signals such as 802.11 a/b/g and the recently proposedWiMAX [2] systems, as shown in Fig. 2. Although OFDM systems are less susceptible to relatively narrowband jammers, nonlinearities in the receiver can result in jammer cross-modulation with wideband input signals, resulting in reduced signal-to-noise ratio (SNR) and a degradation in system performance [3]. In addition, received wideband signals (from other UWB transmitters) can intermodulate and the resulting products can land in a desired channel. Since the system is inherently wideband, harmonic distortion of a single unwanted UWB transmitter can also produce in-band distortion products and reduce the SNR. For the system to successfully operate in such a hostile environment, the linearity specifications of the receiver need to include these distortion effects. .........................

怎么还有括号啊？？？？？？伊诺公司的mVrms等于时0.906 calculatedusing,它等于mVrms当测量传感器0.929阻抗和情绪智商。使用。由此可见,这两种方法都提供类似的结果。实测有效值的输出电压、噪声,是mVrms 0.85伊诺公司。该值非常接近分析计算。图7显示输出噪声的依赖从RT,可以看出 最小的噪声性能为选定的价值。Avalue 10亩用于实时保证正确偏OPA657and噪声性能提供了类似的比更高的价值。最后,输出噪声功率谱密度和细胞输出噪声电压anE4401B-ESA频谱分析仪测量从安捷伦。图8 showsthe的测量数据在ento2连续的线比较 使用与模拟压电激励的表达在dashedline。可以看出,分析模型approximatesclosely实测性能

The Eno is equal to 0.906 mVrms when it is calculated using (23) and it is equal to 0.929 mVrms when the measured transducer impedance and Eq. (17) is used. As can be seen, both methods provide similar results. The measured rms output noise voltage, Eno, is 0.85 mVrms. 运用（23）计算法，Eno 等于0.906 毫伏方均根；而当使用测定的换能器阻抗及方程（17）来计算，Eno 是等于0.929毫伏方均根。显然，这两种计算方式的结果大同小异；输出杂音电压的测定均方根，Eno是0.85毫伏方均根。This value is very close to the analytically calculated. Fig. 7 shows the dependence of output noise voltage from RT, as can be seen the noise performance is minimal for the selected value. A value of 10 MU for RT assures correct biasing of OPA657 and provides similar noise performance than higher values. 这个值与分析法计算的值很接近。图7显示对来自无线电信（RT）的输出杂音电压的依赖，其中可以观察到选定值的杂音性能极小。10微波单元的RT就可确保OPA657的正确偏置磁，并提供与较高值相同的杂音性能。Finally, the output noise power spectral density and the rms output noise voltage has been measured with an E4401B-ESA spectrum analyzer from Agilent. Fig. 8 shows the measured values of ento2 in continuous line compared with the analytically obtained using expression (7) in dashed line. As can be seen, the analytical model approximates closely the measured performance最后，通过使用美国安捷伦的E4401B-ESA型光谱分析仪来测量功率谱密度及输出杂音电压均方根。图8显示ento2的测定值实线和利用（7）表现分析法得出的短划线，两者之间的比较。由此来看，分析模型近似测量的性能。