METHOD OF MEASURING SMALL SIGNAL/NOISE RATIOS AND DEVICE TO THIS EFFECT Russian patent published in 2009 - IPC G01R29/26 

FIELD: physics; measurement.

SUBSTANCE: present invention relates to radio metering, and more specifically to measuring small signal/noise ratios. The method of measuring small signal/noise ratios involves narrow-band filtration of a mixture of signal and noise and subsequent processing. The signal and noise mixture is processed by switching the phase of the high frequency component of the mixture to π each time the envelope curve of the mixture falls to zero. The out-of-band components in the spectrum of the processed signal are separated, and from the ratio of the power of out-of-band components to the total power of the signal, the signal/noise ratio is determined. The device for measuring small signal/noise ratios has a narrow-band filter, the input of which is the input of the device, series-connected first band-pass filter, first squaring device, first low-frequency filter, and a divider, the output of which is the output of the device. The device also contains series-connected second band-pass filter, the input of which is connected to the input of the first band-pass filter, a second squaring device and second low-frequency filter, the output of which is connected to the second input of the divider. The device also has an amplitude-to-phase converter, the output of which is connected to the inputs of the first and second band-pass filter. The amplitude-to-phase converter has a paraphase cascade, the output of which is connected to the inputs of the first and second electronic switches respectively, whose outputs are connected to inputs of the first and second band-pass filters. The amplitude-to-phase converter also has an amplitude detector, the input of which is connected to the input of the paraphase cascade and the output of the narrow-band filter, a comparator, whose input is connected to the output of the amplitude detector, and a trigger flip-flop, whose clock input of which is connected the output of the comparator, and the outputs to control inputs of the first and second electronic switches, respectively. The true output of the trigger flip flop is connected to the control input of the second electronic switch, and the complementary output to the control input of the first electronic switch.

EFFECT: more accurate measurement of small signal/noise ratios.

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