High-speed high-precision impedance data acquisition system based on FFT and CORDIC algorithms

Abstract

The invention discloses a high-speed high-precision impedance data acquisition system based on FFT and CORDIC algorithms, and belongs to the field of electrical impedance imaging. An FPGA controls a DAC to generate a sine excitation signal, the sine excitation signal is input into an analog switch array after passing through a constant current source, an excitation current is injected into an EIT sensor under the control of the FPGA and is sent into an instrument amplifier, a band-pass filter and a fixed gain amplifier through the analog switch array to obtain an analog signal; and the analog signal is sent to a pre-sampling ADC and four high-precision ADCs at the same time; and the signal passing through the pre-sampling ADC is fed back to the amplifier for the control instrument, and gain adjustment is carried out to complete dynamic gain tracking. Then, the FPGA generates four kinds of control clock signals to drive the high-precision ADC to perform parallel acquisition; and finally, a broadband mode correction algorithm or a narrowband mode correction algorithm is used to correct gain mismatch errors and time phase mismatch errors in the four groups of parallel sampling data, amplitude demodulation is completed, and inversion imaging is carried out. The requirements of the biomedicine field on the signal-to-noise ratio and the sampling rate of the electrical impedance imaging system are considered.

Description

technical field [0001] The invention belongs to the field of electrical impedance imaging, and relates to the application of parallel sampling technology in electrical impedance imaging systems, specifically a method based on FFT (fast Fourier transform, fast Fourier transform) and CORDIC algorithm (CoordinateRotation Digital Computer, coordinate rotation digital calculation method) High-speed and high-precision impedance data acquisition system. Background technique [0002] Electrical Impedance Tomography (EIT) is a technology that reconstructs the distribution of conductivity in the imaging region by measuring the voltage value at the boundary of the imaging region. In the EIT system, the number of unknown quantities is usually much greater than the measured quantity , which leads to pathological EIT imaging. In order to alleviate the pathological state of the EIT system, the signal-to-noise ratio of the system is generally increased. [0003] However, the low signal-to-...

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Problems solved by technology

[0003] However, the lower signal-to-noise ratio will lead to the presence of artifacts in the EIT imaging image, which will interfere with the measurement of the instrument

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