查询词典 radio-frequency spectrum

The dynamic performances of the II type and mainframe tripled frequency converter are researched, on the basis of which the experimental mode test of the II type tripled frequency converter is completed and the shell of the mainframe tripled frequency converter is optimized, which has laid the foundation for the following design and improvement.

本文主要针对Ⅱ型三倍频组件和主机三倍频组件的动态性能进行了研究，并在此基础上完成了Ⅱ型三倍频组件的实验模态测试和主机三倍频组件壳体的结构优化，为后续的设计和改进奠定了基础。

to reduce the impact of carrier frequency offset in ofdm system,this thesis designs a new carrier frequency offset estimation scheme for ofdm system.the carrier frequency offset estimation includes acquisition and tracking.we adopt variable step size adaptive algorithm.the acquisition range of the proposed algorithm is as large as one half of the overall signal bandwidth.through this method we can not only avoid the feedback by using forward error correction,but also reduce the times of complex multiplication in order to reduce the power consumption of the system.this algorithm not only has low complexity and fast convergence nut also can improve the demodulation performance of ofdm system.computer simulation illustrates the superior performance of the proposed algorithm with regard to estimation accuracy in both awgn channel and multi—path channel.

摘 要：为了减小正交频分复用系统受频率偏差的影响，在ofdm系统中设计了一种新的载波频偏估计算法。频偏估计包括跟踪和捕获两个阶段，文中采用变步长自适应算法来进行跟踪，这个跟踪算法的捕捉范围是整个信号带宽的一半。通过此方法，不但可以利用前向纠错的方式来避免反馈，而且可以缩减复数乘法的次数以降低计算复杂度和系统功耗。该方法运算复杂度低，并具有较好的收敛性，能改善odfm的解调性能。从计算机的仿真效果可以看出无论是在awgn信道上还是在多径信道上都表现出了卓越的性能。

According to the frequency-domain convolution theorem, we can prove the peak frequency and phase are frequency and phase of the harmonic wave signal.

根据频域卷积定理证明最大峰值点的频率和相位就是信号的实际频率和相位，依据由卷积关系得出的关于幅值的方程求出校正幅值。

Then is the property of fourier transform detally,it contains linar, symmetry,uncover,switch,time-move,frequency-move,time-differentialcoefficient,frequency-differential coefficient,time-intergrate, frequency-intergrate,odd even, theorem of Parseval ,and theorem of convolution,and make testify to some property,some have the example.

接着详细概括了傅立叶变换的性质，即线性、对称性、折叠性、尺度变换性、时移性、频移性、时域微分性、频域微分性、时域积分性、频域积分性、帕塞瓦尔定理、奇偶性及卷积定理等，对某些性质相应的做了推导，并附有适当事例。

Polymorphism was detected for exon 3 of BMP4 gene in four sheep breeds. For exon 3, three genotypes were detected in four sheep breeds. In Small Tail Han, Chinese Merino, Corriedale and South African Mutton Merino sheep, frequency of genotype AA was 0.017, 0.216, 0.115, 0.429, frequency of genotype AB was 0.102, 0.317, 0.269, 0.500, frequency of genotype BB was 0.881, 0.467, 0.616, 0.071, respectively. Sequencing revealed one singlenucleotide mutation C→A at 305 bp of exon 3 of BMP4 gene in genotype BB in comparison to genotype AA, and this mutation resulted in an amino acid change of alanine→aspartic acid.

对于外显子3的引物，在4个绵羊品种中都检测到3种基因型；统计结果表明：小尾寒羊、中国美利奴绵羊、考力代绵羊、南非肉用美利奴绵羊AA基因型频率分别为0.017、0.216、0.115、0.429，AB基因型频率分别为0.102、0.317、0.269、0.500，BB基因型频率分别为0.881、0.467、0.616、0.071；测序结果表明：BB型和AA型相比在BMP4基因外显子3第305位碱基处发生C→A的突变，该突变导致氨基酸由丙氨酸改变为天冬氨酸；BB型小尾寒羊平均产羔数分别比AB型和AA型多0.61只（P.05）和1.01只（P.05）。

In Small Tail Han sheep, Chinese Merino sheep, Corriedale sheep and South African Mutton Merino sheep, frequency of AA genotype was 0.58, 0.98, 0.96, 1.00, frequency of AB genotype was 0.40, 0.02, 0.04, 0.00, frequency of BB genotype was 0.02, 0.00, 0.00, 0.00, respectively. The ewes with mutation homozygous genotype BB or mutation heterozygous genotype AB had 1.45 at 305 bp of exon 3 of BMP4 gene in the BB genotype in comparison to the AA genotype, and this mutation resulted in an amino acid change: alanine—?aspartic acid. The ewes with genotype BB had 0.61 P

结果表明：小尾寒羊、中国美利奴绵羊、考力代绵羊在INHA基因5'调控区发生了1处碱基突变(316C→T)，南非肉用美利奴绵羊没有发生这种突变；小尾寒羊、中国美利奴绵羊、考力代绵羊、南非肉用美利奴绵羊AA基因型频率分别为0.58、0.98、0.96、1.00，AB基因型频率分别为0.40、0.02、0.04、0.00，BB基因型频率分别为0.02、0.00、0.00、0.00；突变纯合型和突变杂合型小尾寒羊平均产羔数分别比野生型多1.45只P

Furthermore, a frequency distribution table can be developed to form a cumulative frequency distribution table which is then used to construct a cumulative frequency polygon or curve.

利用频数分布表亦可再制作出累积频数表，利用累积频数表便可制作累积频数多边形和累积频数曲线。

My company main product 10KW~16000KW's medium frequency power supply for inductionheating and 10kg~50000kg's medium frequency furnace.We also product medium frequency power supply and mechanical device with power needs for consumer special needs etc. such as chain cutter bar's heat treatment device

产品/Product：公司主要生产10KW～16000KW的各种规格中频电源和相配套10kg～50000kg中频感应电炉，以及生产特殊要求的中频感应电源和相配套的机械设备等。

a scheme of channel estimation using cyclic prefix based on the measurement of the low-voltage power line channel model is presented.after obtaining the frequency response of pilot sub-channel under the state of comb-type pilot,the data sub-channel response is obtained by interpolating the frequency response in frequency direction.in the pilot-free data period,the estimation of the channel is carried out by using cyclic prefix in order to improve the performance of system error rate.

摘 要：通过实际测量给出低压电力线的信道模型，在此基础之上提出了利用循环前缀对信道进行估计的方法，即在梳状导频模式时，使用导频获得导频子信道频率响应后，对其在频域方向进行插值得到数据子信道响应，在其后没有导频的序列的数据周期内，使用循环前缀对信道进行估计，从而起到改善系统误比特性能的目的。

Cymometer introduce VHDL language with the frequency of the procedure in detail how to prepare a frequency measurement, how to count the frequency.

详细说明：频率计介绍了用VHDL语言编写的频率计的程序，详细编写了如何测频，如何计数频率。

We got alerted a couple of times while we were down south that HETs were on the way to bring us back up north because things were going to go hot again, but it was just rumors.

南下的途中我们不只一次得到警告说重型装备运输车将拉着我们重新北上，因为局势正在变得重新紧张起来，但这只是谣传。

It's the one where they find the ghost in the salt mine.

这一集是演他们在盐矿找到鬼