SU1393058A1 - Absorption gas analyzer - Google Patents

Abstract

The invention can be used to create multi-component portable, gas analyzers. The aim of the invention is to increase the sensitivity by compensating for the noise signal caused by external influences. The absorption gas analyzer contains a radiation source, a modulator, an optoacoustic detector, and a two-channel measurement circuit, which allows you to effectively isolate the useful signal against the background of noise due to measurements at two close frequencies. 2 or

Description

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The invention relates to a technique for the optical absorption analysis of gases and can be used in the construction of multicomponent portable gas analyzers, designed primarily to monitor small atmospheric pollution.

The purpose of the invention is to increase the sensitivity by compensating for the noise signal caused by external influences.

FIG. 1 shows a block diagram of a gas analyzer; in fig. 2 modulator with clock pulse sensors, a slit.

The absorption gas analyzer contains a source of radiation I, a modulator 2, sensors 3, 4 clock pulses, an optical acoustic detector 5, a preamplifier (preamplifier 6, a selective amplifier 7, synchronized filters 8, 9, different polarity

tectors 10, II, balancing resistor 12, adder 13, register- ing device 14.

The gas analyzer operates as follows.

The radiation of a given spectral composition from the source I through the modulator 2 enters the opto-acoustic detector 5, filled with the measured gas mixture. When radiation is absorbed by the component being measured in an optoacoustic detector 5, a signal is generated at the modulation frequency fc. This signal, containing the components of the useful signal and noise, is amplified by the preamplifier 6 and fed to the input of the selective amplifier 7 tuned to the frequency of the useful signal. The signal from the output of the selective amplifier 7, partially filtered from noise, enters two channels: An absorption gas analyzer containing a radiation source arranged in an optical sequence, a modulator with a clock sensor, an optical-acoustic radiation detector, an electronic unit including a preamplifier connected to an optical-acoustic detector and recording device, about tl and 50

measuring and reference, each of /

which contains narrowband synchronization, in order to

increasing the sensitivity due to compensation of the noise signal caused by an external influence, the modulator is equipped with additional sensors of clock pulses, and the electronic unit additionally contains a selective amplifier, two synchronous filters, two different polarity detectors, a balancing resistor and a matrix, while the outputs of the clock sensors are connected to the inputs control of synchronous filters, the inputs of which are interconnected and connected to the output of the selective filter 8 (9) filter bands do not overlap , And the detector 10 (II), and the detectors 10, And different polarities. The synchronous filter 9 of the measuring channel is tuned to the frequency of the useful signal f, which is achieved by applying to its control input clock pulses from sensor 4 with frequency mnfc where w is the number of blades of the modulator, n is the number of links of the synchronous filter. After being rectified by the detector 11, a constant component is produced at its output, due to both the useful signal and the noise.

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lying in the passband of the synchronous filter 9.

To ensure effective com-. The noise frequency of the tuning of the synchronous filter 8 of the compensation channel should be at a minimum value from the frequency f. This condition corresponds to the setting of synchronous filter 8 on the frequency

(pu ± P | e

 what is achieved by feeding

to its control input there are clock pulses from sensor 3 with frequency (sp11) s,. After being rectified by the detector 10, a constant component is produced at its output due to noise, and the polarity of this signal is due to the corresponding switching on of the detector opposite to the polarity of the signal of the measuring channel. After passing the adder I3, the noise components are mutually subtracted, and the recording device 14 captures the useful signal. Resistor 12 allows

to balance the noise components during device setup.

The use of the invention makes it possible to significantly increase the sensitivity of the gas analyzer, especially when operating under conditions of increased noise and vibration effects.

Claims (1)

Invention Formula Absorption gas analyzer containing a radiation source arranged in an optical sequence, a modulator with a sync pulse sensor, an opto-acoustic radiation detector, an electronic unit including a preamplifier connected to an opto-acoustic detector, and a recording device Lhz Editor T. Orlovska ig, 2 I Compiled by O. Golubev Tehred M. Didyk Proofreader M. Sharoshi Order 1542 Circulation 508 VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5 fe 1 Subscription