A pgc digital demodulation circuit based on mcu

Abstract

The invention discloses an MCU-based PGC digital demodulation circuit, which includes an STM32F108xG digital processing chip, a power supply circuit, an operational amplifier circuit, a differential drive circuit, a first AD acquisition circuit, a second AD acquisition circuit, a DDS signal waveform generation circuit, and a differential operation circuit. Amplifying circuit and interference signal operational amplifier circuit. Among them, diodes are used at both ends of the positive and negative poles of the power supply circuit ±15V in the present invention, which avoids burning the whole circuit when the positive and negative poles of the power supply are reversely connected. First, the two-way signals are changed into differential input through differential drive, input into the A / D acquisition circuit, and then input into the single-chip microcomputer through A / D processing. The invention has high sampling accuracy, small DC drift, strong anti-interference ability, and structure Simple, stable work and other advantages.

Description

technical field [0001] The invention belongs to the technical field of signal demodulation and relates to a PGC digital demodulation circuit based on STM32F103x8. Background technique [0002] Phase-generated carrier technology (PGC) is a very popular technology in optical fiber sensing technology. It has the characteristics of simple demodulation structure and small hardware requirements. [0003] Chinese invention patent application 201110302332.1 is based on the phase generation carrier demodulation optical fiber underwater long-distance pipeline leak detection device, which uses the PGC analog circuit demodulation method to demodulate the signal detected by the optical fiber sensing system. There are a series of such demodulation methods Problems: (1) The temperature drift of the analog circuit module chip will cause the DC drift of the output signal, and this DC drift is difficult to fundamentally eliminate; (2) PGC demodulation is implemented in the form of an analog c...

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Problems solved by technology

[0003] Chinese invention patent application 201110302332.1 is based on the phase generation carrier demodulation optical fiber underwater long-distance pipeline leak detection device, which uses the PGC analog circuit demodulation method to demodulate the signal detected by the optical fiber sensing system. There are a series of such demodulation methods Problems: (1) The temperature drift of the analog circuit module chip will cause the DC drift of the output signal, and this DC drift is difficult to fundamentally eliminate; (2) PGC demodulation is implemented in the form of an analog circuit, which cannot give full play to the technology. The advantages of arraying, while the system performance is greatly affected by the characteristic parameters of resistors and capacitors, the stability is poor, and the circuit is large in size and inconvenient to configure; (3) New noise may be introduced into the PGC analog demodulation circuit, which is different from the useful signal. Aliasing and amplification form noise accumulation and are difficult to separate, which is not conducive to the extraction of detection signals; (4) The interference noise in the PGC analog demodulation circuit is large, which has a great impact on the detection signal, resulting in low positioning accuracy of the detection system

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