查询词典 modulation

Laser technique ; modulation-free laser frequency locking ; acousto-optic modulation ; molecular absorption line

激光技术；无调制锁频；声光调制；分子吸收线

But, in the natural and artificial signal, a lot of signal phases don\'tvary linearly with time, for example, we usually use chirp signal in the radar technology,frequency step signal, linear modulation component of the ground echo in the SARtechnology, linear modulation component of the moving target echo, linear modulationcomponent while the airborn radar detecting the moving target, etc.

在自然界和人工信号中，许多信号的相位变化并不是随时间一次方变化，如雷达技术中常用的线性调频信号，频率步进信号，另外，SAR 技术中，地面回波所含有的线性调频分量，ISAR技术中，运动目标的回波所含有的线性调频分量，机载雷达探测运动目标时的线性调频分量，等等；傅里叶变换对此类信号分析所得的结果是信号在不同频率点上的能量分布，即信号在基函数上的投影。

Integrating trellis-coded modulation with threaded algebraic space–time block code, trellis-coded modulation space-time block code is presented, which has the advantage of full-diversity and small detection delay. Based on TCM pre-processing, the minimum distance between different codeword matrixes of the TCMST block code is maximized, so the average bit error rate of the TCMST block code is lower than that of the TAST block code at the same signal noise ratio.

TCMST分组码具有满发送分集度和检测延迟小等优点；由于采用了TCM预处理，使得不同TCMST分组码码字矩阵间的最小距离达到了最大化，因此在相同信噪比情况下，TCMST分组码具有比TAST分组码更低的平均误比特率。

It is a combination of the pulse amplitude modulation and frequency modulation types.

该仪器系统是由脉冲幅度调制和频率调制两种遥测系统复合组成的。

Amplitude modulation: The form of modulation.

调幅：调制的一种形式。

Frequency modulation minimizes noise and provides greater fidelity than amplitude modulation, which is the older method of broadcasting.

调频最大程度的减小噪音，并且比调幅的保真度高，调幅是一种较老的传播方法。

The performance of 2-level pulse amplitude modulation and analogue pulse width modulation system based on self-error-correction code was analyzed.

基于自纠错码的二级脉冲幅度调制与脉冲宽度调制光纤传输技术，对系统中的接收机灵敏度进行了分析。

The modulation that function of modulation of in-house AM, FM, PM, FSK makes the instrument can go to the lavatory is undee, and need not sole modulation source.

内部AM、FM、PM、FSK调制性能使仪器能够便利的调制波形，而无需零丁的调制源。

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。

In the last new years , as the demands of wireless communication system grows rapidly , the bands of microwave frequency had been saturated with various communication applications . To achieve wider spectrum for high-speed and high-capacity transmission , bands of millimeter-wave frequency are the solution of this problem . The advantage of MMW wireless communication systems is wider bandwidth comparing with microwave communication systems . To utilize the spectrum efficiently , many methods of complexly digital modulation is proposed . The more complex modulation , the higher linearity is required , and more various phase of signals are required to accomplish process of modulation . Therefore high-linearity and quadrature-phase modulator and demodulator are the emphasis of this thesis . For high level of integration , high performance and low cost , this chip is fabricated by the complementary oxide semi-conductor 0.13um process . A compact size of direct down-conversion and direct up conversion circuits will be presented in this thesis .

近年来随著无线通讯产业的蓬勃发展，微波频带已经趋近於饱和，为了追求更宽的频谱来达到更快传输速率及高资料容量的传输，宽频的毫米波频段提供了解决此问题的途径，毫米波无线通讯系统提供了相对於微波通讯系统宽频的优点，且为了更有效的使用频谱，各种不同且复杂的数位调变方式及方法被发表出来，越复杂的调变方式其所需的线性度越高，且需要更多不同的相位讯号来完成调变的过程，因此高线性度及四相位的调变及解调器将是此篇论文的研究重点，为了达到高整合性，高效能，及低成本的电路设计，我门利用互补式金氧半导体制程来完成此电路设计，因此一小面积的直接降频(Direct down-conversion)及直接升频(direct up-conversion)电路将在文中介绍。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。