查询词典 radio frequency

The paper investigates both block-type pilot linear minimum mean square error algorithm and IEEE802.16 OFDM channel estimation analysis. Simulation results confirm the block-type pilot structure is more suitable for IEEE802.16 system. An optimal pilot setting algorithm, based on space frequency domain, is explored and the pilot chart is presented. The proposed algorithm finds its application in MIMO-OFDM. Simulation results show the algorithm presents a good approximation to the perfect channel state information curve, with about 2dB difference in SNR. The simulation results also demonstrate the algorithm achieves fairly high stability in the environment of fast fading, performance of the proposed algorithm is better that of pilot training channel estimation.3. Taking into account the characteristics of IEEE802.16 OFDM system, OFDM system simulation platform is constructed in Matlab, exploiting simulink as a tool. OFDM modulation and demodulation simulation system are configured on LabVIEW platform. All the system signal processing is simulated, including defining system parameters, designing modulation model, and verifying all the proposed algorithms under different environments, such as white Gaussian noise, multi-path fading, with or without guard interval etc. Bit error performance is evaluated. The research provides valid theoretical basis for practical OFDM system performance evaluation.4. Taking advantage of software radio, the paper designs a hardware platform with both 256-IFFT/FFT and 512-IFFT/FFT OFDM schemes co-existing in one platform. You can predetermine one from the two schemes to carry out almost the same model function with different system performance and parameter setting.5. Referring to IEEE802.16 standard, the paper proposes a design method for generating signals and frames suitable for laboratory investigations implemented in laboratory environment.6. Based on 6701evm digital evaluation card, combined with analogy front-end, the paper designs a DSP software model to deal with baseband signal processing. An overall OFDM scheme, with modulation and demodulation function, is accomplished.

讨论分析了MIMO-OFDM中一种基于空频域的最优导频设置算法，给出了导频图案，通过仿真实验表明，该算法与理想的信道状态信息曲线非常接近，信噪比差距约在2dB左右，并且在快衰落条件下具有较好的稳定性，其性能要优于基于前导训练的信道估计方法。3、根据IEEE802.16OFDM系统特点，论文分别在Matlab中应用Simulink工具构建OFDM系统仿真平台、在LabVIEW平台上实现了OFDM调制解调仿真系统，模拟了整个系统的信号流程，进行了OFDM仿真系统参数的选择和调制模块的仿真设计、论证各算法性能，并根据各种不同的条件：例如高斯噪声、多径衰落、有无保护间隔等，对系统的误码特性进行了评估，为正确评价实际OFDM系统的性能提供了有效的理论依据。4、论文以软件无线电思想作为指导，提出了以256点IFFT／FFT为核心和以512点IFFT／FFT为核心的两种OFDM算法模式并存于同一个硬件平台、且可预选的方案，它们在参数选取和性能指标上有所差异，均实现了相似的模块和功能。5、论文参考IEEE 802.16无线网络标准的参数设置，针对本设计系统的应用环境和系统硬件的性能速率，提出了一种应用于实验室环境的信号结构、帧格式等参数设计。6、论文基于TI公司的6701evm数字评估板卡，结合模拟前端搭建数字中频平台，设计了基带处理的DSP软件模块并进行系统调试，基本实现了一套完整的OFDM调制解调方案。

Once you are there, set your radio channel to the directed frequency and begin gathering information.

当你到达那里时，把你的无线电信道调整到指定频率然后开始收集情报。

However, for the wireless mobile communication systems, the radio channel is frequency selective and time-varying.

对于无线通信系统，无线信道不仅是频率选择性的，而且是时变的。

In a multipath radio channel, frequency selective fading can result in large variation in the received power of each carrier.

在一个多路径收音机频道中，选择的时尚频率能造成每个运送者的被一般承认力量的大变化。

In engine room radio jamming field intensity, when the frequency range is 0.15-1000MHz is not bigger than 120dB.

机房内无线电干扰场强，在频率范围为0.15—1000MHz时不大于120dB。

The radio knife is high frequency power equipment based on the theory that electricity concentrates on the skin. It can directly cut the tissue, homeostasis and cauterize. The safety requirement of this equipment is very strict because unsafe operation will burn the tissue, cause temporal unaware hurt and even endanger the patient's life.

高频电刀是利用高频电流的&集肤效应&原理，使高频电流对人体组织直接进行切割、止血或烧灼的一种高频大功率电器设备，故其安全性要求极为严格，一旦出现安全问题，将出现灼伤，还可能造成一些暂时难以觉察的影响，甚至导致生命危险。

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工程方面-主要承接以下业务：智能大厦、智能小区弱电系统集成总包工程、综合布线系统工程、计算机网络系统集成工程、计算机机房工程、接地、防雷工程、防盗报警、闭路监控系统工程、公共广播、背景音乐系统工程、（机关、学校、工厂及卡拉OK）多功能厅音视、频及会议系统、灯光音响系统工程、门禁IC卡、电动门、可视对讲门铃系统工程、停车场自动收费系统工程、远程电话、电视会议系统工程、公司立足于广东、面向全国，主要客户包括银行、税务、邮电、铁路、公司、国家机关、物业公司等。

Just hook up this transmitter, then tune in your portable radio to your desired frequency and listen to your heart's content!

刚刚接上这发射机，然后调重弹在您的便携式无线电至您想要的频率，并听取你的心的内容！

Furthermore, they continuously transmit radio signals of low power and ultra high frequency. They are also equipped with atomic clocks. When GPS receivers intend to calculate its GPS position on the earth, they will receive the signals from satellites, calculate transmission time with a pre-stored ephemeri, and then calculate the distances between themselves and at least four GPS satellites with the method of trilateration.

所有的卫星架有原子钟，当GPS接收器要找出自己目前在地球表面上的位置时，会接收各卫星的讯号，并依储存的星历表计算传送时间，再利用三边测量法订出自己与至少四颗GPS卫星之间的精确距离，即可算出所在位置。

According to the invention, at least two radiocommunication systems overlap spatially and the radio interface in a radiocommunication system comprises at least a first and a second frequency band.

本发明的出发点在于，至少有两个无线通信系统在空间上重叠，而且在一个无线通信系统中无线电接口包括至少第一和第二频带。

I am accused of being overreligious," she said in her quiet, frank manner,"but that does not prevent me thinking the children very cruel who obstinately commit such suicide.""

客人们在卡罗利娜·埃凯家里，举止就文雅一些，因为卡罗利娜的母亲治家很严厉。

Designed by French fashion house Herm è s, this elegant uniform was manufactured in our home, Hong Kong, and was the first without a hat.

由著名品牌 Herm è s 设计，这件高贵的制服是香港本土制造，是我们第一套不配帽子的制服。