SU1547517A1 - Gas analyzer - Google Patents

Description

(46) 06.23.91. Bul & 23

(21) 4400347/25

(22) 03/31/88

(71) Institute of Physics, Academy of Sciences of the BSSR

(72) VB Dunaev (53) 535.36 (088.8)

(56) Copyright certificate of the USSR 1114150, cl. G 01 N 21/61, 1984.

USSR author's certificate number 1267884, -kl. G Ol N 21/61, 1986,

(54) GAS ANALYZER. (57) The invention relates to analytical instrumentation and can be used to control the selection of dew-industrial enterprises and motor vehicles to the atmosphere as well as to control technological processes associated with the release of gaseous substances. The aim of the invention is to improve the accuracy of measurement. niy The gas analyzer contains an optically coupled radiation source, a modulator, a working and a reference cell, a light flux focusing system, a radiation receiver whose output is connected to a variable gain amplifier connected in series, a synchronous filter, a synchronous detector and a recorder, a feedback circuit - with output of the amplifier, a power latch and a storage unit to the control input of the amplifier with an adjustable transmission coefficient, as well as a clock generator connected to by turns - outputs with modulator, synchronous filter and synchronous detector. In the gas analyzer, the amplification of the working and reference signals, their normalization by the sum signal, eliminating the influence of the power level, the radiation source on the measurement result, occurs in the common amplifying path, g of which is normalized by adjusting the gain of the amplifier by the sum signal, which eliminates measurement error due to the temporal instability of the gain of the amplifying path, and allows a 3-fold or more increase in measurement accuracy. 1 il. .

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The invention relates to analytical instrumentation and can be used to control emissions of industrial enterprises and motor vehicles to the atmosphere, as well as to control technological processes associated with the release of gaseous substances.

V The purpose of the invention is to improve the accuracy of measurements.

The drawing shows the block diagram of the detector.

The gas analyzer contains a radiation source 1, a modulator 2, a working 3 and a reference 4 cell, a light flux focusing system 5, a radiation receiver 6, a synchronous filter 7, a synchronous detector 8, a synchronizing pulse shaper 9, a recorder H), an amplifier 11 with adjustable

transfer coefficient, latch 12 level, block 13 of the drive.

The gas analyzer operates as follows.

The radiation from source 1 is transmitted through working 3 and comparative 4 cells, if necessary. It is filtered by spectrum and focused by system 5 onto the receiving area of radiation receiver 6. Using a modulator 2, the radiation fluxes of the working and comparative channels are fed to the radiation receiver 6 with a shift in time, i.e. alternately modulating the radiation fluxes in the working and comparative channels. The output electric signal of the radiation receiver is amplified in the amplifier 11 with an adjustable transmission coefficient, which changes its transmission coefficient in inverse relation to the signal fed to its control input. The amplified signal is fed to the inputs of the synchronous filter 7 and the latch 12 level. With the sync filter 7, a variable rectangular difference signal is obtained with a duty cycle of approximately 2 and a frequency equal to the modulation frequency of the radiant fluxes. The operation of the synchronous filter 7 is controlled by means of a generator of 9 clock pulses associated with the modulator 2.

In the synchronous detector 8, the output of the synchronous filter 7 is amplified if necessary, and then detected and filtered. The operation of the detecting device, which is included in the composition of the synchronous detector 8, is controlled by means of a generator 9 of clock pulses. The output signal of the synchronous detector 8, proportional to the concentration of the measured component, is analyzed in the recorder 10.

The feedback circuit, including latch 12 and accumulator block 13, serves to eliminate the effect of changes in radiation intensity

source on the value of the measured signal. The storage unit is made, for example, in the form of a filter of lower t frequencies. With such a reverse circuit structure, the control input of the amplifier 11 is given a signal proportional to the sum of the flows of the working and reference channels, with obtaining

at the output of amplifier 11 amplified

signal normalized relative to the signal proportional to the sum of the flows of the working and reference channels. Since the amplification signals

the working and reference channels and their normalization by adjusting the transmission coefficient of amplifier 11 by the sum signal occurs in the Common amplifying Path, the measurement error of the difference signal due to the time instability of the transmission coefficient will be minimal. Normalization of the measured signal can be carried out and

separately for reference or operating signal.

Claims (1)

Invention Formula Gas analyzer containing optically coupled radiation source, modulator, working and reference cells, focusing system of light fluxes and radiation receiver, as well as a synchronous filter, a synchronous detector, which controls the inputs through the clock pulse generator connected to the modulator, syn output A chronic detector is connected to a recorder, characterized in that, in order to improve measurement accuracy, an amplifier with an adjustable transmission coefficient, a level lock, and a storage unit connected to the control input of the amplifier with an adjustable transfer coefficient, the output of which is connected via a synchronous filter to a synchronous detector.