Digital modulation and demodulation laser dust monitor and monitoring method

Abstract

The invention provides a digital modulation and demodulation laser dust monitor and a monitoring method. The monitor includes: a digital processing unit, which generates a digital modulation signal and sends it to a digital-to-analog conversion drive circuit; a digital-to-analog conversion drive circuit, which converts the digital modulation signal into an analog signal to drive a laser diode; The modulated laser is generated under the drive of the light source; the light source collimator mirror filters the modulated laser, and the filtered laser is irradiated on the dust particles and hits the detector; the detector generates a photoelectric signal and sends it to the amplifier circuit; the amplifier circuit amplifies the photoelectric signal and sends it to the detector. To the analog-to-digital conversion circuit; the analog-to-digital conversion circuit converts the amplified photoelectric signal into a digital quantity and then sends it to the digital processing unit; the digital processing unit demodulates and filters the digital quantity of the photoelectric signal to obtain the photoelectric signal strength, and calculates the photoelectric signal strength The product with the scattering coefficient of the dust particles gives the dust concentration value.

Description

technical field [0001] The invention relates to the technical field of laser dust monitoring, in particular to a digital modulation and demodulation laser dust monitor and a monitoring method. Background technique [0002] The dust monitor is based on the principle of laser forward scattering method. Dust particles are proportional to the intensity of scattered light under the irradiation of measured modulated light, so the more dust, the stronger the scattered light. Since the scattered light of the dust in the laser dust meter is very weak, in order to amplify the weak signal with high precision, to suppress the interference of ambient light and the drift of the photoelectric sensor, it is necessary to modulate the photoelectric signal to suppress the interference of ambient light, the drift of the photoelectric sensor, and the laser light source. Drift and drift of the system itself. Laser dust detectors generally use analog circuits to realize signal modulation and dem...

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Problems solved by technology

[0004] Moreover, the inventors found that the structure of the analog circuit is complicated, and the precision of the electronic components is very high, it is easy to introduce noise, there are many drift links, and it is difficult to debug and maintain the circuit.

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