A microprocessor-based dual slope phase meter

A dual-slope phase meter has been designed and tested to investigate its limitations. The design does not require a time standard; it offers good resolution, relative simplicity, low sensitivity to changes of internal circuit parameters, and microprocessor compatibility. The idea is based on a single-slope approach demonstrated by W.T. Davis (1986), but several disadvantages of the system have been eliminated. The main problem with the system, relating to the error due to the finite time of sampling, is discussed     

Linearized invariant conductance and capacitance meter for liquids

We consider an automatic conductance and capacitance meter for liquids with linear readout. Two variable resistors are used for balancing the circuit. Translated from Izmeritel'naya Tekhnika, No. 9, pp. 44–45, September, 1996.     

A microprocessor-based digital flickermeter

A flickermeter is an instrument able to simulate and measure the human optical sensation caused by illumination variations due to small-amplitude, low-frequency changes of mains power supply voltage. A flickermeter that has been designed, constructed, and found to meet the internationally agreed performance specifications set out by the IEC (International Electrotechnical Commission) is described. The system, already in commercial service, has been implemented around a microprocessor and presents a full range of I/O interfaces for possible applications in a variety of operational environments. Several unique and demanding design obstacles are related, along with experiences in achieving their solutions. Particular attention is directed to the matter of a nonlinear-phase filter design, task that required a novel Darwinian evolutionary approach which exploits non-equispaced frequency sampling in order to simultaneously satisfy both harsh step response and frequency response accuracy constraints     

A microprocessor-based gamma-ray spectrometer with gain stabilized single-channel analyzers

The design and performance of a self-contained microprocessor-based gamma-ray spectrometer for use in geophysical measurements using nuclear techniques is described. The instrument uses single-channel analyzers which are inherently simpler and faster than the Wilkinson or successive approximation ADC. A novel technique of gain stabilization together with a simple means of energy calibration has been developed. The modular design of the equipment makes it suitable for multidetector usage, required in a number of nucleonic gauges for the quantitative measurement of chemical constituents.     

A microprocessor-based on-line optical transfer function (OTF)measurement system

The development of a microprocessor-based optoelectronic system for the measurement of the optical transfer function (OTF) is considered. The method used is based on the edge image analysis. The edge intensity distribution data are stored in the microprocessor, and the computation of OTF from these data is made using the process software. The present technique avoids the differentiation and makes a clever use of edge data as such. The practical difficulty of instrumentation of the FFT technique for the required Fourier transformation has been avoided by the use of Walsh block expansion of the function to be Fourier transformed. The details of the programming as well as some experimental results using standard lens are also reported     

A high performance, variable capacitance accelerometer

A variable capacitance acceleration sensor is described. Manufactured using silicon microfabrication techniques, the sensor uses a midplane, flat plate suspension, gas damping, and overrange stops. The sensor is assembled from three silicon wafers, using anodic bonds to inlays of borosilicate glass. Typical sensor properties are 7-pF active capacitance, 3-pF tare capacitance, a response of 0.05 pF/G, a resonance frequency of 3.4 kHz, and damping 0.7 critical. It is concluded that this sensor, with appropriate electronics, forms an accelerometer with an order-of-magnitude greater sensitivity-bandwidth product than a comparable piezoresistive accelerometer, and with extraordinary shock resistance     

A capacitance ultrasonic transducer for high-temperature applications

This paper introduces a novel ultrasonic capacitance transducer for operation at elevated gas temperatures of several hundred degrees Celsius. The transducer design is based on a metallic membrane foil and a backplate made of an electrically conducting substrate coated with an insulation layer. Guidelines are given for selecting suitable materials for the membrane foil, the backplate substrate, and the coating. Manufacturing techniques applied for fabrication of different transducer types are described in detail. Transducers tested were composed of titanium substrates with insulation layers of silicon nitride or of silicon substrates with silicon oxide coatings. Experimental setup and test procedures are described. Results of transducer characterization and performance tests at elevated temperatures are presented and discussed. Transducer functionality is proven for air temperatures of up to 500 degrees C.     

A heat meter of finite thickness

The two-dimensional steady-state problem is solved for a heat meter of finite thickness. Corrections to the heat meter readings are estimated.Notation q_o unperturbed heat flux - q_H heat flux recorded by heat meter - heat-transfer coefficient - thermal conductivity - thickness of heat meter - R radius of heat meter - J_o, J₁ zero- and first-order Besael functions - T₁, T₂ temperature distributions of semi-infinite wall and heat meter - T_o temperature distribution of wall in the absence of heat meter Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 5, pp. 835–842, November, 1979.     

A digital frequency independent phase meter

A digital, frequency-independent phase meter is described. It makes use of pulses derived from the multiplication of the frequency of the reference input signal as its clock pulses instead of conventional crystal controlled clock generators. Advantages of the meter include simplicity and the elimination of gating error. The main source of error for this circuit is harmonic distortion of the input signals     

一种精密电容测试系统设计

该文介绍一种基于自动平衡电桥的精密电容测试系统设计方法,通过对激励信号与自动平衡电桥输出信号进行鉴相分析,给出被测电容值的计算方法。为使鉴相器处于最佳工作点,得到精度更高的电容值测量结果,系统对自动平衡电桥输出信号进行反馈,并根据反馈结果,结合标准电阻选择与程控放大器对信号进行调理。最后,在1 MHz的测试频率下对系统的电容测试精度进行验证,得出设计的电容测试系统具有较高的测试精度。