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Presented is a study of application of open-ended coaxial probe for in-line measurements of moisture content of pharmaceutical powders during mixing processes. The procedure utilizes a multivariate calibration technique relating the moisture content to the spectrum (1-19 GHz) of a density independent function derived from the permittivity epsi' and the loss factor epsi" of the powder samples...
In this paper, we present an autocalibration procedure for tri-axial MEMS accelerometers, which allows increasing the accuracy of this kind of micro-sensors. This makes them usable for the analysis of the human movement. The procedure is based on the constancy of the module of the accelerometer output in static condition, and it is formulated and resolved as a non linear least squares problem. The...
This paper presents the concept of reconfigurable sensing channel characteristics inverse model in auto-calibration measurement systems, particularly for water quality measuring systems. The inverse model implementation is supported on an advanced FPGA reconfigurable embedded control and acquisition system (CompactRIO). Model blocks, such as polynomial and neuronal, are on-line updated (reconfigured)...
In this paper a general purpose multi-sensor data acquisition module with broadcasting capabilities and a field programmable logic array (FPGA) at its core is presented. The system, through its FPGA core, has the ability to directly measure sensor impedance and implements a 4th-order multivariable polynomial regression (MPR) to model and compensate both each sensor nonlinear characteristic and the...
This paper presents a digital capacitor error-averaging calibration technique for pipelined analog-to-digital converters (ADCs). The scheme utilizes a 1.5b/stage digital calibration algorithm and extends it to assess capacitor ratio-mismatches. This is accomplished by using an algorithm similar to analogue capacitor error-averaging (Song, 1988) which is performed in the digital domain. This calibration...
A method to correct for gain errors in each channel of a parallel delta-sigma (PiDeltaSigma) converters in real-time is presented. The calibration technique requires an additional channel that is linearly dependant on PiDeltaSigma channels used. By introducing the redundancy in a system, the adaptive LMS algorithm can be used to correct for gain errors within the channels. Using a 16-channel PiDeltaSigma...
Thermographic devices which are able to acquire images, such as infrared line scanners, are becoming increasingly popular. One of the major issues when working with this kind of devices is accurate spatial calibration, necessary in order to extract metric information from images. In this work, a spatial calibration procedure for infrared line scanners is proposed. The proposed procedure is based on...
A traceable current source for the calibration of low-current meters (picoamperemeters, electrometers) in the 100 fA-100 pA current range is here presented. It is based on a low-frequency trapezoidal wave generator, measured with a sampling voltmeter, which charges and discharges a gas-dielectric capacitor. The generated current is traceable to units of voltage, capacitance and time. The source is...
The increasing diffusion of pollutant measuring units which are installed over wide areas along with the short calibration interval of several sensors for pollutant quantities requires new calibration infrastructures to be developed. This paper describes an attempt to develop an innovative calibration system which is based on traveling standards and which does not require a unit to be removed from...
This paper deals with the problem of the regression of measured quantities when measurement uncertainty affects both the regressed quantity and the independent variables. A new criterion is given, based on an enhanced full least-squares (FLS) method. The approach shares with the FLS similar metrological foundations, but it differs in that the propagation of the measurement uncertainty is performed...
Sensor measurement systems rely upon knowledge of the functional dynamics between system states and the measured outputs. Errors in sensor measurements come from a variety of source. While there are well known techniques to compensate for those that result from such issues as noise and sensor accuracy limitations, other types of errors, such as those that are more deterministic, can result in biases...
This paper presents a measurement setup which enables power amplifier characterization driven by radio frequency modulated signals. Incident and reflected absolutes waves at both ports of the device under test can be measured even in a source pull or load pull environment. The structure and the calibration procedure of the setup are explained. Measurements examples are shown and then used in order...
Self-calibration methods for long-term monitoring of non-electrical quantities are presented in the paper. There have been discussed the self-calibration methods of measurement channels containing integrated ratiometric output sensors and ratiometric output sensors with strong attenuation (bridge circuits). It has been shown that under certain system solutions this type sensors make measurement results...
A growing number of measurements in commercial and industrial sector needs to refer to the traceability to the national (and also international) standards. Since the Internet-enabled metrology is rapidly developing in the recent years, it offers new possibilities for calibration services. In the same time these services must provide the overall security of the calibration data from the point of acquisition...
Transient disturbances are, probably, the most dangerous and virtually harmful disturbances in the electric power networks. They are also the most difficult to detect, due to their transient nature and random occurrence, and, in most cases, their extremely short duration. These same reasons make testing and calibrating the instruments employed for their detection a very difficult task, since the test...
In the electrical measurement practice, the measurements of the quantities related to the safety and preventive maintenance of the electrical distribution system are very important. Due to the potential risk caused by wrong measurements, it is necessary to assess the status of the employed measurement system at all times, and assure the measurement traceability too. This means to calibrate the instrument...
Recent developments for biosensors have been mainly focused on miniaturization and exploratory use of new materials. It should be emphasized that the absence of an "in-situ self-calibration/diagnosis technique" that is not connected to an external apparatus is a key obstacle to the realization of a biosensor for continuous use with minimum attendance. To address this deficiency, a needle-type...
In this paper, we proposed a visual position calibration method using colored rectangle signboards for a mobile robot which is designed to work in a room environment. The rectangle signboards are placed in several known positions. By calculate the vanishing points in the image of the signboard, it is possible to obtain the relative direction and distance between the signboard and the robot by a single...
Barkhausen emission is well known phenomena used in non-destructive testing techniques of ferromagnetic materials. Weaknesses of the methods based on Barkhausen emission are related to difficulties of ensuring measurement reproducibility because of specimen influence upon measurement channel. In this paper we propose method of sensor calibration prior to measurement. To implement sensor calibration...
Sensor calibration plays an important role in instrument development and accuracy. This paper presents a method to calibrate current and voltage sensors specially dedicated to power quality measurements which can significantly reduce the distortions introduced by the sensors. The first approach to sensor calibration is based on the response of sensors to DC values imposed by a calibrator. The second...
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