外文翻譯--- - 傳感器和傳感器激勵(lì)和測(cè)量技術(shù)-全文預(yù)覽
【正文】 hase error, which is the need for correction. In addition, the DSP also need to deal with some plex mathematical calculations, this may require external memory to store the original data of the ADC, which would further increase costs. Address the abovementioned analysis of the issue of lowfrequency sensor solutions AD5933 / 4 device, it will by the main processing module are integrated into one chip. The core of the chip, including three main modules: the frequency of scanning for the direct digital synthesizer (DDS) waveform generator。s industrial and instrumentation applications involving sensor. The function of the sensor system is to monitor changes, and then this data back to the main controller. For a simple voltage or current measurement sensors may be resistance in nature. However, some sensor system may be inductive or capacitive in nature, that is to say, the frequency range of the sensor resistance change is nonlinear. Impedance sensors such typical example is the proximity sensor a campaign for the detection of the relative distance of objects。 and, finally, to the ADC data for 1024 point Discrete Fourier Transform (DFT) calculations of the DSP engine. The results of DFT calculations to provide a real part (R) and an imaginary part (I) data, which can easily calculate the impedance. Using the following formula is easy to calculate the impedance amplitude and phase: In order to determine the actual value of the real impedance Z (ω), is typically required to perform frequency scanning. Can calculate the impedance of each frequency point, which can draw a relationship between frequency and amplitude curves. So it is easy to measure 100 Ω ~ 20 MΩ resistance within the scope. The system allows users to set up a 2 V peaktopeak (PKPK) of the sinusoidal signal as an external frequency source excitation load. Output range can be set to 1V, 500 mV and 200 mV. Frequency resolution can be 27 bit ( Hz). The realization of the frequency of scanning: In order to achieve the frequency of scanning, the user must first set up the required frequency of scanning conditions: the need for a start frequency, frequency interval and sweep points. Then the need for a start mand to start scanning. Frequency points in each scan, ADC pleted the first 1024 samples, and then calculating the DFT in order to provide the waveform of the real and imaginary parts of the data. The real and imaginary parts of the data through the I2C interface in the form of two 16 bit words available to the user. DSPchip processing unit user does not have the advantage of plex mathematical calculations, and need not store ADC raw data, only two 16 bit data. Therefore, it allows the DSP to choose cheaper solutions, as greatly reduce the processing power of the final requirements.Without calibration of the system as a result can only use the typical value of sensitivity and offset the output voltage is converted to pressure, the pressure measured will have a margin of error as shown in Figure . This initial error without calibration by the following ponents: error: As the pressure in the entire range of vertical shift to maintain a constant, so the proliferation and laser conditioning converter changes the amendment would have offset error. sensitivity of error, resulting in errors in direct proportion to the size and pressure: If the device is higher than the ty
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