数字信号

a kind of design project of multifunction electric power quality gauged instrument based on virtual instrument is put forward in this article.this system integrates virtual instrument programming and power electronics together,to realize diverse signals of current electric power quality field allin one.the integrated signal generator unit which carries out the collection of high speed digital data,d/ a conversion and analog output in four channels,unsymmetrical synchro control fifo etc.by fpga are introduced,the flow of electric power system various signal which generates by vc programming is elaborated,and the structural design of signal amplification unit is analysed.the experiment text result shows that this gauged instrument has attained current advanced high grade of accuracy and it will accelerate the steps of electric power quality calibration because of its accuracy and versatility.

摘 要：提出一种基于虚拟仪器技术的多功能电能质量标定仪的设计方案，采用虚拟仪器编程技术和电力电子技术相结合实现集目前电能质量领域的多样信号于一体。介绍采用fpga实现高速数字量采集、d/a转换及4通道模拟量输出、非对称同步控制fifo等的集成信号发生单元，阐述利用vc编程实现的电力系统多样信号的产生流程，分析信号放大单元的结构设计。实验测试结果表明该标定仪达到目前先进的高精度等级，由于其准确性和多功能性将加快电能质量标定的步伐。

According to the demand of high magnetic field power supply, reference is increased with a set ramp rate and stops at a set stable value, so reference system is composed of digital setting and digit to analog converting circuit. But the stability of reference is mostly guaranteed by the performance of D/A circuit, so D/A circuit is particularly studied in reference system. The scheme of D/A circuit, the selection of DAC and its voltage reference, hardware anti-jamming design and PCB design are discussed in detail, and software of remote control and PLC are discussed in brief. Zero-flux DC current transformer well satisfies the demands of the high stability of Load current detection unit, so the principle of zero-flux DC current transformer is analyzed; in the mean time a project which detects the long term stability is designed. During 8 hours, analog signal which is detected with high precision digit multimeter is recorded in computer at 1HZ frequency by GPIB communication. The drift error source and related parameters are explained in the compare-amplify part. Detailed subtraction circuit is designed; also amplifier chip and periphery components are selected and verified according to the theory of error analysis.

根据强磁场电源的需求，参考源应按照软件设定的斜率逐渐上升到设定稳态值，则参考源系统应由数字给定和数模转换电路两大部分组成，而参考源的稳定度主要依靠完成数模转换功能的模拟电路的性能来保证，因此本文对参考源系统的研究以数模转换电路为重点，分别从电路方案的确定、数模转换芯片及其基准电压源的选取和验证、电路板硬件抗干扰和PCB设计几方面进行了论述，然后对数字给定部分的远控组态和PLC程序设计作了简要介绍；采用零磁通原理的直流电流转换器很好地满足了对负载电流检测单元高稳定度的需求，本文详细分析了零磁通检测的原理，并在选定此种类型电流转换器的基础上设计了一套检测长期稳定度的方案，8小时内以1秒为采样周期，通过计算机Labview程序和高精度数字电压表的GPIB通讯，将被高精度数字电压表数字化后的模拟信号采样值连续记录至计算机中；比较放大环节简要阐述了漂移产生的原因和相关参数指标，确定了具体的减法电路形式，并根据误差分析理论对运算放大器和外围元器件进行了选取和验证。

C. electric parameters measurement. The means and conditions to reestablish the signal without distortion are also given. At last, this paper discusses the theoretical basis for power, RMS and harmonics phase measurements of power system directly from the Harr wavelet matrix transform data associated with each sampling voltage and current element pair.

本文针对电力系统特点，分析了非均匀采样的数字频谱结构及非均匀采样周期信号的数字谱表达式，并讨论了非均匀采样对交流电量参数测量的影响，给出了非均匀采样无失真恢复信号的方法和条件。

The image watermarking is permuted to reduce the relativity of original pixels, so the error bits of the extracted watermarking are dispersed as well. Therefore the resistance to crop attack is improved significantly.

对数字水印信号进行置乱分散了原始水印信号的相关性，在遭到剪切攻击时可以将错误码元尽可能分散，因此有效地提高了数字水印算法的抗剪切攻击性能。

The image watermarking is permuted to reduce the relativityof original pixels, so the error bits of the extracted watermarkingare dispersed as well. Therefore the resistance to crop attack isimproved significantly.

对数字水印信号进行置乱分散了原始水印信号的相关性，在遭到剪切攻击时可以将错误码元尽可能分散，因此有效地提高了数字水印算法的抗剪切攻击性能。

The A to D converter converts the analog signal to a digital file or signal.

A 转换器传输到D转换器（模拟转换器转换到数字转换器）将模拟信号转换到数字文件或信号。

MD are analog sensors, the digitizing happens when the electrons are passed through the analog to digital converter. The A to D converter converts the analog signal to a digital file or signal.

CD 属于模拟传感器，当电子从模拟转换传输到数字转换器时实现数字化。A/D转换器将模拟信号转换到数字文件或信号。

Make signal be called binary system numeral to make for the make of binary system signal, the binary system make and is divided into a binary system to move key to control(2 ASK), the binary system Pin move key to control(2 FSK), the binary system mutually move key to control(2 PSK) with bad cent the binary system mutually move key to control(2 DPSK) etc. variety basic type, this topic main is numeral the frequency make and call Pin to move key to control.

调制信号为二进制信号的调制称为二进制数字调制，二进制调制又分为二进制幅移键控（2ASK）、二进制频移键控（2FSK）、二进制相移键控（2PSK）和差分二进制相移键控（2DPSK）等多种基本的类型，本课题主要是数字频率调制又称频移键控。

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。

Secondly, we study on the integration of digital signals of acceleration sensors. We proposed a scheme that processes the discrete time signals by two-pass filter and digital integrator.

其次，针对加速度传感器信号积分的需要，研究了使用数字积分解决该问题的可行性；提出了信号经双通滤波后再使用数字积分器进行积分的方案。

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。