PGC digital demodulation circuit based on gd32f103zet6

Abstract

The invention discloses a phase generated carrier (PGC) digital demodulation circuit based on a GD32F103ZET6 digital processing chip. The PGC digital demodulation circuit comprises the components of the GD32F103ZET6 digital processing chip, a zero crossing detection circuit, an external expansion RAM circuit, an AD conversion circuit, a DDS signal waveform generating circuit, a carrier differential operation amplifier circuit and an interference signal operation amplifier circuit. According to the PGC digital demodulation circuit, the end of the carrier differential operation amplifier circuit and the end of the interference signal operation amplifier circuit are provided with operational amplifier chips; and the end of the carrier signal is also provided with a differential amplifier chip so that an original signal is amplified without distortion. Firstly acquisition of two signals in an A / D format is changed to acquisition of one signal, and the other signal is input into a single-chip microcomputer through the zero crossing detection circuit. Then the signal is acquired through modulation of the single-chip microcomputer. The PGC digital demodulation circuit has advantages of high sampling precision, high DC drift, high interference resistance, simple structure, high working stability, etc.

Description

technical field [0001] The invention relates to the digital signal demodulation technology in the optical fiber sensing technology, in particular to a PGC digital demodulation circuit based on GD32F103ZET6. 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 demodulati...

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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. At the same time, 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 noises may be introduced into the PGC analog demodulation circuit, which are different from useful signals. 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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