Embedded System for Impedance Measurement (original) (raw)
Related papers
Impedance measuring system based on a dsPIC
2010
This paper describes a device based on a dsPIC (Digital Signal Peripheral Interface Controller) as a processing unit, capable of making impedance measurements at multiple frequencies. A DDS (Direct Digital Synthesizer) stimulates the measurement circuit composed by the reference impedance and the unknown impedance. The voltage across the impedances is amplified by programmable gain instrumentation amplifiers and then digitized by analog to digital converters. To measure the impedance, a seven-parameter sine-fitting algorithm is used to estimate the sine signals across the impedances. The dsPIC is connected through RS-232 to a computer where the user can view the measurement results.
Implementation of DSP based algorithms for impedance measurements
ICSPC 2007 Proceedings - 2007 IEEE International Conference on Signal Processing and Communications, 2007
In this paper, two DSP based algorithms are implemented for impedance measurements. The algorithms (the sevenparameter sine-fitting algorithm and the ellipse fitting algorithm) are implemented and tested in a commercial DSP kit. The complete system is used to compare the algorithms by measuring 105 different impedances, using the four-wire impedance measurement method. The strategic selection of appropriate reference impedances, intrinsic to the impedance measurement method, is also described. The results of each algorithm are compared in terms of speed and accuracy. This is the ground work for a portable DSP based impedance measurement device to be implemented in specifically designed hardware.
DSPIC-Based Impedance Measuring Instrument
Metrology and Measurement Systems, 2011
An implemented impedance measuring instrument is described in this paper. The device uses a dsPIC (Digital Signal Peripheral Interface Controller) as a processing unit, and a DDS (Direct Digital Synthesizer) to stimulate the measurement circuit composed by the reference impedance and the unknown impedance. The voltages across the impedances are amplified by programmable gain instrumentation amplifiers and then digitized by analog to digital converters. The impedance is measured by applying a seven-parameter sine-fitting algorithm to estimate the sine signal parameters. The dsPIC communicates through RS-232 or USB with a computer, where the measurement results can be analyzed. The device also has an LCD to display the measurement results.
Application of compensation techniques in a dsPIC based impedance measuring system
2011 IEEE EUROCON - International Conference on Computer as a Tool, 2011
A dsPIC (Digital Signal Peripheral Interface Controller) based impedance measuring system was developed and implemented. The system measures the impedance's amplitude and phase at the desired frequency using a sine-fitting algorithm running on the dsPIC and the results are sent to a personal computer using an USB or RS-232 connection. The measurement results are also shown in an LCD included in the device. This paper describes the system and details the OPEN and SHORT compensation techniques used to correct the measurements obtained with the device.
Comparison of Three Impedance Analysers Implemented on FPGA Circuits
2015
— In this paper, we present three different methods we have developed for the design of an electrical impedance analyser implemented on an FPGA board. We describe in the first part the general principle of the methods: Ratiometric Measurement, Feedback Voltage Control and Adaptive Parametric Modelisation. In order to test and to compare the performances of each approach, the Hardware In the Loop strategy has been used. We present the steps from the mixed simulation using Matlab DSP Builder, which leads to the FPGA implementation. We investigate the limits and advantages for each method. The impedance analysis results of a model of an audio piezo transducer (7 kHz) are presented. The amplitude accuracy is less than 3 % and the analysis duration from 5 kHz to 10 kHz is about 54.5 ms for the first two methods.
A broad-bandwidth mixed analog/digital integrated circuit for the measurement of complex impedance
IEEE Journal of Solid-State Circuits, 1993
A broad-bandwidth measuring system for complex impedances is presented. The measuring principle, based on synchronous detection, is worked out mathematically. The final circuit is realized as a mixed analog/digital BiCMOS integrated circuit. The output of the IC is a modulated 100-kHz frequency and RS232. The phase accuracy of the system is 0.07' at 20 MHz and is mainly determined by parameter deviation of transistors that share the same IC. The circuit enables measurement of a capacitance of up to 100 pF with an accuracy of k l pF, in parallel with a conductance of up to 100 mS. Apart from the impedance measuring circuit, the IC can process signals from other sensors, such as for temperature or pH. The design criteria for the IC are derived from the primary application in a sensor for water content and ionic concentration measurements in soil or other agricultural substrates.
Colloids and Surfaces B-biointerfaces, 1992
A broad bandwidth measuring system for complex impedances is presented. The measuring principle, based on synchronous detection, is worked out mathematical. The final circuit is realized as a mixed analog/digital BiCMOS integrated circuit. The output of the IC is a modulated 100 kHz frequency and RS232. The phase accuracy requirement of the system is mainly determined by parameter deviation of transistors which share the same IC. The phase accuracy of the circuit is according to PSPICE simulations 0.07° at 20 MHz. This enables to measure a capacitance of 100 pF, in parallel with a conductance of 100 mS, with an accuracy of ± 1 pF. The requirements are based on the application of the IC in a sensor for water content and ionic concentration measurements ments in soil or other agricultural substrates.
Design of a Portable Low-Cost Impedance Analyzer
Proceedings of the 10th International Joint Conference on Biomedical Engineering Systems and Technologies, 2017
Impedance analyzers available in the market are mostly bulky and often very expensive. In this paper, a low-cost, portable impedance analyzer is designed and implemented. The design utilizes the well-known, impedance network analyzer chip AD5933 and is capable of measuring a spectrum of impedances in the range 5 Hz to 100 kHz from 10 Ω to 100 kΩ. Its specifications allow it to be used in agriculture for monitoring the bio-impedance of fruits in different stages of their lives, especially during the growth period while maintaining low-cost.