AOTF Driver Used For Wheat Quality Detecting Device And Spectral Analysis Technology

China is a large agricultural country. Recently near infrared spectroscopy technology is replacing traditional chemical methods and becoming the standard agricultural measurement method due to its non-contact, non-destruction, and rapid automation. AOTF spectrometer has obvious advantages Compared to the mechanically-tuned spectrometer, AOTF spectrometer has obvious advantages of no internal moving parts, scanning speed, high resolution and high signal to noise ratio. In the foreign country, currently AOTF spectrometer has been commercialized, but the price is expensive. In china, the AOTF spectrometer is still in the experimental stage, there is a certain distance from market stage. In the AOTF near-infrared spectrometer system, a stable RF signal source is of significant importance.Therefore, the main contents of this thesis include the following items:1. Design of the DDS circuit. According to the principle of the AOTF, a RF signal sourse circuit based on the DDS is designed, including the filter circuit and the power amplification circuit. Comparing two frequency synthesis schemes, the PLL and the DDS, the DDS is employed for this thesis. A passive 150MHz lowpass filter and a 1W power amplification circuit are designed.2. Design of the computer programming for the system according to the DDS chip timing. Through the SPI interface, the communication between the MCU and the DDS chip enables the transmission of frequency and waveform data, and the conversion of the frequency.3. Design of the power amplifier. A two-stage cascade amplifier circuit is designed to amplify the power of the small signal from the DDS output. The InGap amplifier chip RFGA2054 is used for the amplitude amplification. The RF power field effect transistor MW6S04N is used for the power amplification. This amplifier circuit outputs a 80-150MHz/1W RF signal to drive the AOTF module.4. The wheat spectrum is experimental analyzed. In this thesis, wheat is used as the experimental subject. The true value of wheat protein is measured by the national standard method and the wheat spectral data is analyzed by the spectral analysis technology. Four data preprocessing methods are compared for optimization.