METHOD OF DETERMINING CHANGE IN CONTENT OF HARMFUL GASES IN AIR Russian patent published in 2020 - IPC G01N22/00 

FIELD: measurement.

SUBSTANCE: invention relates to the field of electrical measurements and can be used in analytical and measuring systems for continuous monitoring of atmosphere parameters. When monitoring changes in content of harmful gases in air, a microwave signal, amplitude-modulated by a low-frequency synchronizing signal, is emitted on a controlled route. Then microwave signal is received by relay and amplified, then low-frequency clock signal is separated from it, which is used to synchronize local reference generator using automatic phase frequency control system. A monotonically increasing (or decreasing) phase shift is then added to the microwave signal and then the frequency-transformed microwave signal is emitted back. After homodyne conversion of the frequency of the secondary received microwave signal and the initial one, a low-frequency information signal is extracted, which contains information on the integral composition of the monitored air, which is converted using a phase detector into a signal proportional to the microwave signal phase advance. Further, the signal is transmitted to the input of the decision block, where signals are also sent, which are proportional to changes in air humidity and temperature. In the decision unit, the required calculations are performed, consisting in subtraction of the air moisture meter signal from the signal of the phase detector, with a certain reduced coefficient depending in its turn on the temperature of the analyzed air. At that, at the output of the decision unit, a signal is obtained, which is proportional solely to change in content of other gases and suspended impurities in the air, having harmful effect on living organisms.

EFFECT: higher accuracy and reliability of determination is achieved.

1 cl, 1 dwg