振动监测系统的可调增益技术与实现

文章设计了一种具有可调增益功能的振动监测系统。首先从监测层和测量层两个方面提出了振动监测系统的整体框架,之后给出了硬件系统和软件系统的设计方法及软件实现代码,利用控制芯片和可调增益放大器,在监测系统中整合了一套可根据采集信号幅值大小调整增益的数据采集装置;利用模拟信号发生器对不加增益和设置可调增益之后的两种信号进行了对比分析,并在汽轮发电机组实际工况下进行了振动信号采集。结果表明,具备可调增益功能的振动监测系统可有效提高采集信号的信噪比,提高汽轮发电机组的振动监测能力。     

随钻测量中工具面角的模拟解算

针对井眼轨迹的测量问题,根据测量仪器的输出信号与钻具姿态信息存在一定的三角函数关系,提出了一种工具面角模拟解算方法.分析了工具面角数字计算方法及其误差,基于模拟函数发生器构造了一种新颖的反正切函数求解电路,可以直接获取工具面角.对不同井斜角和工具面角的情况下进行了试验测试,数据分析表明,该方法可行,并具有较高的精度,可用于快速的姿态参数解算.     

Uniform sampling of periodic signals using successive conversions

This paper presents a new approach to the generation of uniform sampling signals which is based on multiple signal conversions: from pulse to digital, then from digital to analog and afterwards from analog back to pulse. It is shown that a conventional analog-to-frequency converter is suitable to be used as a controllable pulse generator providing for equidistant sampling pulses the frequency of which is proportional to the sampled signal frequency. This paper describes two methods for designing fast response, jitter-free sampling-time generators allowing accurate, uniform sampling of periodic signals. The prototypes have been built and tested     

高频医学断层成像系统的硬件设计

详细论述了高频医学电阻抗断层成像(EIT)系统设计的关键技术,其中包括激励信号源、电压控制电流源、模拟开关阵列以及信号解调等环节。设计了基于数字信号处理器(DSP)的主从式数据采集系统。PC机作为主控机,进行可视控制、图像重建、实时显示等操作;DSP实现电极选通、数据采集并与PC机进行数据通信。该系统具有数据采集速度快、使用灵活、可扩展性强的特点。     

Synthesising gene clock with toggle switch and oscillator

The usefulness of a genetic clock lies in its role to stimulate a sequence of logic reactions for sequential biological circuits. A clock signal is a periodic square wave, its amplitude alternates at a steady frequency between fixed minimal and maximal levels. Transition between the minimum and the maximum is instantaneous for an ideal square wave; however, the function is unrealisable in physical bio‐systems. This research develops a new genetic clock generator based on a genetic oscillator, in which, a sine wave generator is adopted as a signal oscillator. It is shown that combination of a genetic oscillator with a toggle switch is able to generate clock signals forming an efficient way to generate a near square wave. In silico study confirms the proposed idea.Inspec keywords: genetics, oscillators, biological techniques, square‐wave generators, switchesOther keywords: toggle switch, genetic clock, logic reaction sequence, sequential biological circuits, clock signal, periodic square wave, physical biosystem, genetic clock generator, sine wave generator, signal oscillator, genetic oscillator     

Data compression using the deconvolution algorithm CLEAN

We describe an application of the nonlinear deconvolution algorithm CLEAN in which a priori knowledge of the point-spread function allows transmission of nonredundant information. We refer to this as CLEAN compression. The point-spread function is viewed as a redundancy function. The data set may be regarded as a convolution of the nonredundant information with the redundancy function. Since the nonredundant data is a small subset of the overall data set, images or telecommunication messages may be transmitted over narrowband channels using CLEAN. Effective analog data compression is maximized; the analog signal may be significantly compressed with CLEAN even before any additional compression or digital encoding algorithms are applied.©1994 John Wiley & Sons Inc     

调相信号的数字化解调

通过单周期正弦波曲线模型的滑动拟合法,获得正弦序列的瞬时频率信息,使用对瞬时频率的积分运算,实现了正弦载波相位调制信号波形的精确解调.在调制信号是方波的情况下,给出了相位解调的仿真结果和其它参数的波动情况;在1个实测调相曲线波形上进行的解调分析,给出了相位调制波形的解调结果;在调制信号也是正弦波的情况下,给出了解调失真的计算方法和结果.本方法用于评价载波为正弦波的调相信号时,具有准确度高、分辨力高的特点,可用于调相信号源及其解调设备的指标评价和计量测试.     

The implementation of a digital sine wave oscillator using theTMS320C25: distortion reduction and applications

The implementation of a digital sine wave oscillator using the TMS320C25 digital signal processor (DSP) is described. The system is implemented with the Dalanco Spry model 25 DSP board, and a software system is designed whereby an IBM PC host computer provides control of the waveform generator functions and parameters. Waveforms are generated using the lookup-table (LUT) method. The methods of direct LUT and linear interpolation of missing samples are implemented and compared with a method that uses a trigonometric identity to reduce the harmonic distortion of the sine wave by effectively increasing the table length of the direct LUT method. The results of an experiment performed in the digital domain are presented without consideration of the problem of analog reconstruction. The oscillator can produce a sine wave without the nonuniform sampling distortion associated with fractional addressing, over the range of 7.2 Hz to 58.8 kHz, with a resolution of 7.2 Hz using 384 data words. The trigonometric identity method uses less data memory than other methods for the same distortion levels. Waveforms for the sum of two sine waves, a frequency swept sine wave, amplitude modulation (AM), and frequency modulation (FM) signals are shown as applications of the waveform generator     

A Technique for Synthesizing Digital Filters

In designing digital systems, one often faces the task of replacing a given analog filter by an equivalent digital filter. This paper proposes a method for synthesizing such digital filters in the time domain. It is assumed that the pulsed transfer function of the digital filter is a ratio of two rational polynomials. The coefficients are then determined by least-square fitting the digital filter to the analog filter's sampled input and output data. The resulting equations for computing the coefficients are linear. It is shown that the digital filter is essentially related to the analog filter, the sampling time, and the power spectrum of the signal being processed. If the signal is band-limited and the sampling frequency is sufficiently high, the digital filter can then be simply approximated by the Z transform of the analog filter multiplied by the sampling period.     

调频信号的数字化解调

介绍一种用3参数正弦波拟合算法实现的、绝对收敛的4参数最小二乘正弦波拟合算法，给出了其收敛区间、绝对收敛判据以及实现过程，在此基础上讨论实现正弦载波的调频信号的精确解调问题，使用一个周期的正弦波曲线模型的滑动拟合法，实现了频率调制信号波形的精确解调，在调制信号是方波的情况下，给出了频率解调的仿真结果和其它参数的波动情况；在1个实测调频曲线波形上进行的解调分析，给出了频率调制波形的解调结果，同时，在调制信号也是正弦波的情况下，给出了解调失真的计算方法和结果。本方法是评价载波为正弦波的调频信号的一种优良方法，准确度高、分辨力强，可用于调频信号源及其解调设备的指标评价和计量测试。     

应用于边带调制PDH激光稳频的信号源设计

基于直接数字频率合成芯片AD9959、锁相环芯片ADF4351,结合开源电子平台Arduino（基于微处理器ATmega328）,建立参考到同一个外部频率参考的多路信号源,能够输出频率为0 Hz～4.4 GHz的正弦波,频率、相位、幅度可以通过USB端口和控制面板灵活控制,通过混频和叠加等手段,产生边带调制PDH激光稳频需要的调制信号和解调信号。该信号源集成度高、成本低且能在实验室条件下替代商品仪器应用于边带调制PDH激光稳频等实验,解决了限制边带调制PDH激光稳频推广应用的一个重要障碍。     

高g值加速计和压电式力传感器的动态校准

本提出一种高g值加速度计的动态校准方法和装置,其最大加速度峰值超过100000g。这套装置还可以对压电式力传感器进行动态校准。中给出两个加速度计加速度峰值的二十余次实验结果,以及加速度计与力传感器的冲击响应实验曲线。同时,还求出它们的动态数学模型（包括差分模型、传递函数、频率特性）和动态性能指标。此外,还讨论了本的4个创新点。     

A computer-controlled eight-channel pulse generator

An eight-channel pulse generator able to generate signal transitions synchronized to an internal 10-MHz clock or an external clock is described. The time intervals between transitions can be programmed arbitrarily with a time resolution of one clock period. The generator is realized as a PC add-in board.     

Evaluation of the design requirements for the electrical part oftransmission-type optical smoke detector to improve its thresholdstability to slowly varying influences

The output signal sensitivity to optical component contamination and other slowly varying parasitic influences in the transmission-type smoke detector is analyzed. The analysis carried out the new topology characterized by the selective feedback loop incorporating the optical part of the detector. Depending on the loop gain frequency shaping in the electrical part of the loop, dual-stability enhancement of the input threshold level can be achieved. The stable dc output signal can be preserved by the high dc loop gain value, as an option to the standard serial filter dc rejection. The detector passband gain stability is achieved by the high loop gain selectivity, eliminating feedback at very low or passband frequencies. The proposed topology can be easily adopted to both digital and low-cost analog detector designs. The special case of the threshold sensitivity neutralization through the cancellation of the output dc signal sensitivity and passband gain sensitivity is considered, too, as an option suitable for low-cost detectors. In addition to the described linear settlement, two nonlinear solutions are presented, the first of them based on the foregoing linear circuit analysis. Despite its nonlinear nature, this alternative solution is not troublesome for analog implementation, since the nonlinear function required is realized by the standard variable gain amplifier. Another nonlinear method requires logarithmic function implementation, so that its suitability depends on the particular design requirements     

Effect of laser pumping power on the SRS-CARS signal in compressed hydrogen

In the context of developing the diagnostics of hydrogen in gas mixtures by means of coherent anti-Stokes Raman scattering (CARS) in combination with biharmonic laser pumping by means of stimulated Raman scattering (SRS), the effect of laser pumping power on the SRS-CARS signal in compressed hydrogen has been studied. It is established that an increase in the pumping power at the input of the SRS generator leads to a shift of the CARS signal intensity maximum measured as a function of the gas pressure in the cell. This behavior is probably explained by changes in the positions of energy levels, which are caused by a significant modification of populations in the SRS process at high laser pumping powers.     

An analog core memory for pulse-width modulated signal

This paper describes the results of studies on an analog core memory with the aim of applying them to the process controllers. The analog information is stored as the flux level of the square-loop magnetic core. The "write-in" and "read-out" of flux level are achieved by the pulse-width modulation techniques. The storage errors are introduced by the deviations from the ideal square-loop characteristics. However, improvements of stability and linearity are obtained by the following methods: 1) negative dc bias ampere-turn is applied to the square-loop magnetic core, 2) two magnetic cores are connected in the push-pull circuit configuration, 3) the pulse-width modulated (PWM) signal is employed as the "write-in" and "read-out" signal. The experimental results of this device show that the accuracy of analog information storage is better than 0.5 percent at the cycle-time of 1 ms. The PWM signal has both analog and digital characteristics and is suitable for the sequential analog arithmetic computation. An analog-digital hybrid computing control system is outlined to show how these devices can be utilized.     

基于比例阀门的升降速度控制方法研究

提出了一种新的航空升降速度标准信号自动产生方法.从控制方面,采用硅压阻模拟、石英数字双传感器,分别作为过程控制传感器和基准压力传感器,保证系统升降速度的准确度.采用双闭环控制方案,模拟闭环采用电路设计实现,数字闭环通过计算机、数字传感器和软件实现.控制执行部件采用一对比例电磁阀门.控制电路设计采用了模拟电路PID和数字PID控制结合的串级控制方案,对实现升降速度和压力信号变化的微分电路进行了设计.实验证明,该装置升降速度的输出准确度优于0.2%F.S,控制范围为0～200 m/s.     

EVM可控的数字调制信号的产生方法研究

针对数字信号发生器检定装置和信号分析仪期间核查缺乏产生EVM值可控的数字信号标准装置的情况,在理论推导加性高斯白噪声环境下的EVM与SNR之间的解析关系基础上,提出了基于噪声发生器和数字信号发生器的EVM值可设置的数字调制信号产生系统方案。对系统输出的BPSK信号和64QAM信号展开重复性和稳定性测试,测试结果表明,尽管理论设置值与实际值之间存在一定的差距,但并不影响任意EVM值数字调制信号产生系统的稳定输出,其重复性和稳定完全可满足数字信号发生器校准装置或者矢量信号分析仪的期间核查的需要。     

深水通讯节点中基于脉冲采样的高能效SPWM发生系统设计

近年来,深水探测中水下通讯节点的小型化、低功耗成为设计的难点。在水声通信中,普遍使用正弦脉宽调制(Sinusoidal Pulse Width Modulation, SPWM)信号驱动功率放大器进行工作。传统SPWM产生系统电路复杂度高,针对SPWM生成原理和电路实现,提出基于脉冲采样的SPWM生成方法,并进行性能分析;基于数字处理器设计了高能效SPWM发生系统,在保证SPWM信息损失较小的同时,减小硬件电路面积。实验结果表明,提出的高能效脉冲采样法与SPWM发生系统可以满足工程应用。     

Electronic influences on an infrared detector signal: nonlinearity and amplification

For mercury-cadmium-telluride detectors, frequently used in Fourier transform IR spectroscopy, the recorded signal is a nonlinear function of the light intensity. This behavior depends on a series resistor in the electronic circuit and thus the illumination of the detector. This nonlinearity must be accounted for to avoid spectroscopic errors. The results of theoretically calculating the effect permit a correction that can be applied, with corresponding lower accuracy, even after a phase correction. Also the use of the amplification stages does influence the phase of the signal electronically. For an accurate nonlinearity correction, compensation of the amplification of the analog signal is advisable.