A fast and high-precision measurement of distorted power based ondigital filtering techniques

A rapid high-precision measurement of distorted power is described. The measurement is based on digital filtering techniques. The convergence conditions of two previous sampling algorithms are derived, and their frequency responses are analyzed. An adjustable window used for measuring distorted power is also proposed. It is demonstrated that the sampling algorithm using the window leads to significant savings in measuring and computing time, and high accuracy can be obtained     

Error analysis of digital phase measurement of distorted waves

An analysis of errors associated with the digital measurement of phase angle between two signals, one of which may be distorted by a harmonic, is presented. All the results were found by running a simulation program on a VAX 11/780 computer. The results are very useful for the users of the phase meters. This technique may introduce large errors for some particular types of input waves. The main purpose of this work is to explain how large the error could be under certain conditions on the input waves     

Calculation of spectral parameters and filtration of periodic digital signals

We consider algorithms for calculation of the parameters of the spectrum of periodic digital signal with increased resolution. We propose a filtration method based on determination of the spectrum of the digital input signal with subsequent recovery of the filtered signal.Translated from Izmeritel'naya Tekhnika, No. 10, pp. 58–60, October, 1995.     

Real-time integration and differentiation of analog signals bymeans of digital filtering

A novel filter design method for broadband recursive digital integrators and differentiators is presented. The performance of the digital infinite-impulse response (IIR) filters designed with the method is compared with that of finite-impulse response (FIR) filters and that of classical numerical integration and differentiation. The common conviction that IIR filters with excellent amplitude characteristics always have poor phase behavior is refuted. It is shown that it is possible to design easily realizable IIR integrators and differentiators with an arbitrarily small amplitude and phase error. While there is no FIR alternative for IIR integrators, both FIR and IIR methods give competitive results for differentiators     

Phase angle measurement between two sinusoidal signals

An algorithm for measurement of the phase angle between two sinusoidal signals is introduced. The algorithm is based on the least-squares method (LSM) and uses digitized samples of two input signals. The algorithm allows the magnitude and phase of the two signals to be determined simultaneously. The key parameters that affect the performance of the algorithm are illustrated, and computer simulation results are presented     

A digital method of frequency measurement for harmonic signals

Conclusions A new method and an algorithm are described for determining the frequency or period of a harmonic signal no matter what the period of the signal. The principle can be used in digital measuring systems, particularly at low and infralow frequencies.Translated from Izmeritel'naya Tekhnika, No. 11, pp. 71–73, November, 1973.     

基于自适应滤波的带宽测量方法研究

用自适应滤波(AF)算法替换带宽测量算法NEPRI中固有的往返时间(RTT)值的测量算法,提出了测量网络带宽的AF-NEPRI算法.采用AF-NEPRI算法测量链路可用带宽时,首先数据发送端发送不同速率的探测包,然后采用自适应滤波算法测量数据包的RTT值,通过相邻数据包的RTT差值计算带宽估测参数,最后估测链路可用带宽...     

New digital multimeter for accurate measurement of synchronously sampled AC signals

An approach to the design of a digital multimeter based on the use of dual-slope ADC is described in this paper. Based on this approach, a new technique for algorithm design is developed. The main advantage of this approach is the determination of all electric values in electric utilities by the same algorithm. The algorithm has high accuracy and a regular structure. Measurements of voltage and current are made in successive periods by a stroboscopic technique (synchronous undersampling). The assumed stationarity of the electric utilities is validated by measurements with an experimental setup, consisting of a fast high-precision sigma-delta ADC. The necessary synchronization is reached by software measurements of the frequency of the measured signal. Assuming stationarity of the observed system (electric utilities) in the stated 1-s interval, it is proved that precise digital processing can be achieved without using a sample-and-hold circuit. The suggested measuring system was simulated, realized in a practical setup, and tested. The obtained results completely confirmed the starting postulates. A processing precision of 0.01% was achieved.     

Optically-supplied voltage transducer for distorted signals inhigh-voltage systems

A new approach to the implementation of a measurement transducer for high-voltage (HV) electric power systems is presented. The power supply for the HV section of the measurement system, together with the required galvanic isolation, is obtained by means of an innovative energy transfer technique from the low-voltage to the HV section. The energy transfer apparatus is based on conversion of the optical power generated by a laser source into the electrical power needed to supply the measurement circuit. The structure of the insulated transducer is based on a capacitive divider and two electrically isolated signal conditioning sections. The proposed solution allowed for designing and developing a novel and high-performance HV transducer for in-field applications. A prototype version of the transducer was constructed following these new design criteria, and the experimental results confirmed a measurement bandwidth as wide as 5 kHz within a 0.5 accuracy class     

Reconstruction of nonlinearly distorted signals with regularized inverse characteristics

A signal distorted by a system having static, invertible, nonlinear characteristics can be exactly restored in the absence of noise. In this case, the inverse of the characteristics can be used. When noise is superimposed to the distorted signal, the inverse characteristics may not be proper because the noise is strongly amplified. This noise has to be suppressed in the reconstructed signal, which can be accomplished only at the price of bias. This article presents a method to compensate the effect of static nonlinearities in the presence of noise. This method is based on Tikhonov's regularization operators and provides a compromise between noisy and biased estimates.     

基于数字锁相的应变放大测量

为解决数据采集现场噪声大,布线安装困难的情况,将数字锁相应用于高精度的应变放大测量中.由于锁相放大在干扰较大的应用现场是最易于实现高精度检测的方法之一,因此在模拟锁相的基础上推出对应变桥路的数字锁相放大检测原理,并根据此原理利用AD8231放大器和C8051F061单片机设计了一个实用的数字锁相测量系统,该系统的分辨率和精度大为提高,有效地降低了现场测试中干扰与布线的难度.     

自适应互补滤波水下高度测量技术

针对传统利用GPS、温度、声呐、压力等手段,对水下高度测量容易受洋流、太阳辐射、季节变化等海洋环境干扰因素的影响而导致测量局限性、精度低的问题,设计一种基于自适应互补滤波的水下高度测量系统。该系统以IMU为信息采集单元,搭建以FPGA+DSP为架构的信息处理解算平台,结合自适应补偿系数的互补滤波算法,在低通滤波环节加入PI控制器,依据加速度计测得的姿态数据判断水下弹体的运动情况,实时调整PI参数,实现水下系统的高度测量。试验结果表明:该水下高度测量系统操作方便、独立性实时性好、测量精度高,具有一定的工程应用价值。     

Statistical-uncertainty-based adaptive filtering of lidar signals

An adaptive filter signal processing technique is developed to overcome the problem of Raman lidar water-vapor mixing ratio (the ratio of the water-vapor density to the dry-air density) with a highly variable statistical uncertainty that increases with decreasing photomultiplier-tube signal strength and masks the true desired water-vapor structure. The technique, applied to horizontal scans, assumes only statistical horizontal homogeneity. The result is a variable spatial resolution water-vapor signal with a constant variance out to a range limit set by a specified signal-to-noise ratio. The technique was applied to Raman water-vapor lidar data obtained at a coastal pier site together with in situ instruments located 320 m from the lidar. The micrometeorological humidity data were used to calibrate the ratio of the lidar gains of the H(2)O and the N(2) photomultiplier tubes and set the water-vapor mixing ratio variance for the adaptive filter. For the coastal experiment the effective limit of the lidar range was found to be approximately 200 m for a maximum noise-to-signal variance ratio of 0.1 with the implemented data-reduction procedure. The technique can be adapted to off-horizontal scans with a small reduction in the constraints and is also applicable to other remote-sensing devices that exhibit the same inherent range-dependent signal-to-noise ratio problem.     

Phase reconstruction of modulated ultrasonic signals and new measurement technique of flow velocity

Streaming fluid modulates the ultrasound as well in phase as in amplitude. The complex bandpass sampling separates the phase and the amplitude information. Because of unknown zero phase adjustment point of the receiving sensor, the demodulated phase signal has to be reconstructed. The reconstruction is based on the analysis of the density distribution function of the phase angle. To determine the transit time of the structures between two ultrasonic barriers two methods can be used. The maximum of the cross-correlation function corresponds to the transit time. The other way is to add the demodulated signal of both barriers. In the spectrum of the added signals after a filtering a cosine function can be determined. The frequency of this function is directly proportional to the transit time.     

Approximation methods of recovering input signals distorted by nonlinear dynamic systems

A contemporary measurement task is considered: recovery of an input signal to a means of measurement, for which algorithms are given.Research supported by the Russian Fundamental Research Fund.Translated from Izmeritel'naya Tekhnika, No. 11, pp. 3–7, November, 1995.     

连续太赫兹波数字全息相衬成像

太赫兹波具有独特的低能性、高穿透性、惧水性等成像特性,将其应用于相衬成像能够反映物体的内部结构和更加丰富全面的生物信息,在生物医学检测等领域具有重要的应用。其中,太赫兹波数字全息成像是一种可以给出定量的振幅和相位信息的非接触、全场相衬成像方法,是太赫兹成像技术领域的重要研究方向之一。本文基于连续太赫兹源,从离轴式和同轴式数字全息成像的相衬成像原理、光路系统和再现算法多个方面,介绍了相关技术的研究现状,分析了太赫兹源、再现算法等因素对成像分辨率的影响,并对太赫兹数字全息的发展趋势进行了展望。     

Microprocessor multimeters based on digital processing of the instantaneous values of signals

A microprocessor multimeter is proposed capable of carrying out a wide range of functions by means of software based on digital processing of the codes of the instantaneous values of the signals in accordance with certain algorithms. An estimate of its errors is given.Translated from Izmeritel'naya Tekhnika, No. 9, pp. 53–55, September, 1995.