共查询到20条相似文献，搜索用时 187 毫秒
1.
马立军 《柳州职业技术学院学报》2009,9(1):99-103
提出一种基于虚拟仪器技术的多通道FFT频谱分析仪设计方案,分析虚拟仪器技术在频谱分析仪设计上的主要流程。给出设计的频谱分析仪组成框图和各模块需要完成的功能实现。重点分析传感器模块、采集模块和嵌入式系统等三个关键模块实现原理与设计优化。最后对仪器的总体性能进行测试与分析。结果证明该方案简单实用,具有较高的性价比。 相似文献
2.
3.
在使用波束成型传输数据的蜂窝系统中,为提高下行链路的频谱效率,需要多小区多用户之间协作地产生波束.以多小区多用户下行链路的数学模型为基础,计算了各用户波束发送滤波器、接收滤波器、发送功率三类变量的梯度,使这些变量不断沿梯度方向调整并投影至可行空间,从而提出了一种基于梯度投影的多小区多用户下行协作波束成型传输方案,并分析了该方案需要在相邻小区基站间交互的信息.仿真结果表明,该方案在典型场景与参数配置下可达到约5 bit/（s·Hz·cell）的平均频谱效率性能.因此,多小区多用户之间的有效协作有助于提高蜂窝系统频谱效率性能. 相似文献
4.
5.
《实验室研究与探索》2017,(7)
为实现宽带卫星中频调制解调器性能的快速验证及性能提升,基于EVM(Error Vector Magnitude)误差矢量分析,结合安捷伦的大型精密仪器(如E4438C信号源、E4440A PSA频谱分析仪、16803A数字逻辑分析仪等),设计了基于EVM检测的卫星宽带中频调制解调器测试平台。通过该平台,能直观、实时分析调制、解调器的EVM值。通过EVM分析,给出中频调制、解调器的优化方向,为宽带调制、解调器的研究提供了有力的支撑,促进了宽带卫星通信系统的科研及教学发展,提高了大型仪器的使用效率。 相似文献
6.
《东南大学学报》2016,(3)
研究了基于图的蜂窝覆叠D2D通信调度算法的性能,该调度算法由频率分配与时隙调度2个阶段组成.针对该算法,提出了一种对D2D子系统的平均频谱效率性能进行理论分析的方法.该方法包括3个步骤.首先,对频率分配阶段进行了分析,推导了被分配使用同一频率资源的D2D链路个数的近似公式.其次,对时隙调度阶段进行了分析,推导了每条D2D链路在单个时隙内被调度的概率的近似公式.然后,对D2D子系统的平均频谱效率性能进行了分析,并推导了相应的理论公式.理论分析结果表明,在基于图的调度算法下,D2D子系统的平均频谱效率与D2D链路的归一化广播半径的二阶原点矩成线性反比关系.仿真结果表明该方法能够准确地预测D2D子系统的平均频谱效率性能. 相似文献
7.
《实验室研究与探索》2017,(8)
为了提高矢量网络分析仪的校准效率,提出了一种用于矢量网络分析仪的电子校准系统。该电子校准系统由端口连接组件模块、电子开关模块、校准接口模块和测试适配座组成。端口连接组件将矢量网络分析仪与电子校准系统相连,利用微处理器控制电子开关的通断实现对校准端口、校准类型及测试器件的选择。最后,以85032F校准套件对Agilent E5062A矢量网络分析仪的开路、短路、负载和传输校准实验为例,验证了该电子校准系统校准功能的可行性。效率测试实验表明,使用该电子校准系统比常规校准方法校准效率提高了约70%,比机械式校准方法提高了约50%。此外,该电子校准系统提高了矢量网络分析仪的校准效率,降低了人为操作带来的误差概率。 相似文献
8.
本文设计了一种基于虚拟仪器技术的频谱分析仪,解决了传统频谱分析仪存在的一系列问题。文中阐述了虚拟频谱分析仪主程序及各功能模块的设计与实现,并设计虚拟信号发生器来验证各种功能。 相似文献
9.
基于虚拟仪器模块化的设计思想,设计出一种以FPGA为硬件基础,Lab VIEW为软件核心的多功能虚拟频谱分析仪。重点分析了硬件电路各个模块的设计方案和上位机软件数据处理方法。硬件电路包括对信号的调理、AD采集转换、存储及传输。另外,系统采用AD9288作为模数转换器,通过AD双路并行8位采样模式,可以提高系统的采样率。软件开发平台采用Lab VIEW,对数据进行滤波、加窗、FFT运算处理,并具有数字显示、图形绘制、存储和查看测试数据等功能。经测试该频谱分析仪稳定可靠,可用于高校实验教学中,具有一定实用价值。 相似文献
10.
利用虚拟仪器技术和USB数据采集卡开发一个多功能电子测量仪,可以实现示波器、滤波器、频谱分析仪和波特图分析仪四种常用物理仪器的测量功能.测试结果表明,该电子测量仪不仅能对信号进行正确地滤波处理,还能准确地测量信号的频谱、频率响应特性及信号的波形.并且,该仪器运行稳定,可靠性强,测量精度高,响应速度快,性能可调,可以满足信号的测量需求. 相似文献
11.
设计了光电传感器实现绝对式振动测量,推导了测试系统的振动方程,方程为常系数二阶微分方程。通过激振器产生20Hz~10 kHz连续变化的振动信号,由光电传感器得到振动波形,Lab VIEW频域分析得到被测体的振动频率分布等。结果表明,光电振动测试系统的输出频率与激振器相同。该振动测试方法具有非接触、远距离、抗电磁干扰、测量精度高、频率响应宽、成本低等优点。 相似文献
12.
As one of the most important components of the wideband wireless access technique, orthogonal frequency division multiplexing （OFDM） has a high usage rate of spectrum and combats inter-symbol interference （ISI） in multi-path fading channel. However, when there are frequency offsets during the signal transmission, the inter-carrier interference （ICI） is introduced, which significantly degrades the performance. The existing ICI self-cancellation schemes such as PCC-OFDM are not optimum to minimize the interference considering both noise and ICI. In this paper, a new metric named S1NR （signal-to-interference- and-noise ratio） is proposed. We discuss the optimization issue when a constant frequency offset exists and in time-varying channels. The optimum weighting-coefficient-pair （OWCP） is obtained, which maximizes SINR theoretically through the alternant iteration algorithm. Simulations show that the performance of OWCP-OFDM is better than that of PCC-OFDM, especially when the frequency offset is large. Although the ICI self-cancellation scheme suffers bandwidth inefficiency, from the simulation results we can also see that the performance of OWCP-OFDM is much better than that of the standard OFDM systems with the same bandwidth efficiency when a frequency offset exists. Moreover, since the redundant modulation provides the capability to suppress ICI as well as a receiving SNR gain, it can be considered as exchanging the bandwidth for SNR. 相似文献
13.
Dynamic response of functional virtual prototyping of motorcycle under combined excitations 总被引：1，自引：0，他引：1
This paper developed 3D product models of motorcycle and engine by UGNX as well as virtual prototyping by ADAMS program with road roughness generated by MATLAB. Under the straight-line running condition, the dynamic responses of motorcycle multibody system to both road and engine excitations were compared with those to only road excitation in terms of vertical acceleration response, amplitude frequency response and power spectral density. The comparisons of simulation data showed that the response due to flat road excitation was around 20 Hz, while that to the combined excitations was in a wide frequency band, of which the major components focused on 10 Hz, 15 Hz, 35 Hz ,70 Hz, 100 Hz and even higher frequencies, reflecting the characteristics of engine excitation based on its unbalanced inertia force and torque. It is concluded that the high fidelity virtual prototyping can simulate the dynamics of motorcycle product well in investigating the vibration and ride comfort performance. 相似文献
14.
陈海燕 《泰州职业技术学院学报》2004,4(1):4-6
探讨和比较载波通讯中采用的各种门限扩展解调器，分析和比较锁相环门限扩展解调器、频率负反馈解调器、尖峰噪声抵消法解调器、跟踪滤波器解调器的基本原理及实现方法。 相似文献
15.
CDMA扩频通信中m序列与Gold序列的比较及应用 总被引：1，自引：0，他引：1
吴海红 《喀什师范学院学报》2010,31(3):39-43
m序列和Gold序列是CDMA扩频通信中两种常用的伪随机序列.就这两种序列的性质、生成原理进行了详细的分析研究,然后用表格及Matlab仿真的结果将这两种序列的主要性能进行了比较,最后在比较的基础上分析了它们在CDMA扩频通信中的典型应用. 相似文献
16.
As a result of the ever-growing list of course technologies and software programs, higher education faculty and administration often debate which new tools are most valuable to students. This article investigates whether the use of an online textbook supplemental program (MindTap®) has a positive influence on student performance. The impact of goal achievement orientations is also discussed and factored into the analysis, as it provides insight into the motivations that drive the usage of online supplemental course materials. Results found that usage of MindTap® is positively predicted by a mastery approach goal orientation. More importantly, it was shown that usage of MindTap® positively predicts student performance, above and beyond the impact of age, gender, SAT score and goal achievement orientation. 相似文献
17.
This study compared the statistical properties of four job analysis task survey response scale types: criticality, difficulty in learning, importance, and frequency. We used nine job analysis studies spanning two fields, medical imaging and allied health professionals, to compare the job analysis scales in terms of variability and interrater agreement. Results showed that frequency scales using absolute anchors had greater between-task variability and higher interrater agreement for all nine studies. This may have occurred due to what has been described by past research as self-presentation bias. In this case, an aggregate base percentage of respondents always responded that tasks in their domain are highly critical, highly important, and easy to learn. These results showed that frequency scales with absolute anchors yielded data with better statistical performance than other more subjective scales. These properties do not answer the question of whether a scale matches an exam's purpose, which is the most important consideration for job analyses. They do, however, suggest that, if statistics are a primary deciding factor, strong consideration should be given to using frequency scales with absolute anchors. 相似文献
18.
随着计算机技术的发展以及国际互联网络的普及,在线考试已经成为一种重要的考试方式。本文简要介绍了一个在线考试系统的系统分析、基本功能和系统设计。 相似文献
19.
Johanna Vuori 《Tertiary Education and Management》2013,19(4):316-327
This paper examines how institutional positioning has emerged in the meaning-making activities between Finnish higher education institutions and the Ministry of Education and Culture. The study is based on a qualitative analysis of the performance agreement documents of all higher education institutions filed with the ministry for contract periods 2010–2012 and 2013–2016. The results show that, in the first cycle, higher education institutions used profiling vocabulary in vastly different ways, and their lists of priority areas were quite wide ranging. By the second cycle, profiling statements had become more specific and structurally more alike, but the lists of priority areas continued to have a wide scope. As a response, the Ministry has consistently demanded and rewarded more focused profiling efforts and used the concepts of profiling to support other steering measures. 相似文献
20.
名词化隐喻（Nominalization）是创造语法隐喻最有力的方式。研究名词化隐喻在各种语篇中的体现和功能十分重要。名词化隐喻在农业科技英语中的运用十分广泛,具有语篇正式功能、语篇衔接功能和语篇简洁功能。 相似文献