中频

A coupled line U section improves the port to port isolation and provides the IF-output port.

同时电路中还使用U型耦合线改善了端口之间的隔离度并提供了中频输出端口。

The characteristics of human visual system is used to embed the watermarks which is encrypted into mid-frequency subbands coefficients of Y branch of host image after Y branch of host image is transformed by the multilevel structures wavelet transform in the YIQ pattern space.

该算法利用形式简单的二维离散超混沌系统产生的超混沌序列生成密码对水印图像加密，同时根据人类视觉系统的特性，对宿主图像在YIQ色彩空间中的Y分量进行多级离散小波变换后，将加密后的水印图像嵌入到宿主图像Y分量的DWT中频子带中。

This paper is divided in six chapters, including the medium frequency power supply of thyristors theory, design, regulation strategy, control system, experiments and conclusion.

本文的内容主要分为六章，分别阐述了晶闸管中频感应电源的工作原理、主电路设计、控制策略、控制系统实现、试验结果和结论。

The receiver includes: an LNA and downconverter; complete synthe- sizers and VCOs; direct conversion from IF receiver with variable gain control; quadrature demodulator; I/Q base- band amplifiers; and, on-chip baseband filters.

该接收器包括：一LNA和下变频器；完成桑特- sizers和压控振荡器，从中频可变增益控制直接转换接收器；正交解调器，I / Q基带放大器，以及片上基带滤波器。

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。

This paper studies the technology and properties of 60AT NbRE microalloy point rails heat treatment that rail head was heated by medium frequency induction and cooled by pressure air.

AT尖轨全长热处理采用中频感应加热、压缩空气吹冷淬火，对 6 0AT铌稀土微合金道岔尖轨进行轨头全长欠速淬火工艺及性能的研究。

Inevitably this is content-dependent, but you'll spot benefits on vocal articulations and plosives and pretty much any percussive sounds, plus a more rounded performance with low frequencies.

声音现代，适合一般用途，尤其适合想要增加人声、木吉他以及其他乐器高频的Air，中频很宽广，往高频渐渐收窄，使得麦克风摆位相对容易。

Besides, the amount of accelerating the speed to infer the accelerating mechanism of push-off should not be the only condition to accelerate the gravity center.

动态支撑方式中频幅组合的模式特征本研究首次在周期性兑速项目的步幅、步频与步速关系研究中提出区分定点支撑方式与动态支撑方式的概念。

The scope of the gravity center moving forward combined with the suitable opportunity to push-off on the ice side wards is the premise of acquiring the optimum speed.

通过对不同滑行速度中频幅组合与步速之间的关系分析，比较了动态支撑方式与定点支撑方式中的差异在频幅组合上所表现出的异同性。

At present,the company has a complete of production facilities including middle frequency melting furnaces,strip rolling machines,annealing furnaces,thermal press machine,wire drawing machines,wire perform rings machines and fast quenching strip making machine etc.

公司具有十几年的钎料生产经验，拥有中频冶炼炉、轧带机、退火炉、挤压机、拉丝机、制环机、甩带机等生产设备，具有先进的分析、检测手段和完备的质量保证体系。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。