METHOD OF MEASURING FREQUENCY OF RADIO SIGNAL IN ACOUSTO-OPTIC RECEIVER-FREQUENCY METRE Russian patent published in 2011 - IPC G02F1/33 G01R23/00 

FIELD: physics.

SUBSTANCE: analysed radio signal is transmitted to the electrical input of an acousto-optic deflector where it is converted to an acoustic signal and then to an optical signal which then undergoes Fourier transformation with recording of its intensity distribution using an N-element line of photodiodes. Further, video signals are generated at outputs of said photodiodes with levels which are proportional to levels of said intensity distribution, after which frequency of the radio signal is calculated, which matches the abscissa of the axis of symmetry of intensity distribution of the light signal which is discretised by the photodiodes. Together with the analysed signal, two reference signals with frequencies which are close to the lower and upper boundaries of the frequency range of the receiver-frequency metre respectively, is also transmitted to the input of the deflector. For each of the reference signals, a photodiode with maximum signal level is found in the N-element line of photodiodes. The index number of said photodiode is recorded. The signal level on the said photodiode and neighbouring photodiodes is measured. The frequency interval which corresponds to distance between neighbouring photodiodes of the line is calculated, which corresponds to the number of the photodiode with maximum signal level for the reference signal selected close to the lower boundary of the frequency range, and frequencies which correspond to photodiodes with subsequent numbers, used to calculate the abscissa of the said axis of symmetry, are determined.

EFFECT: method increases accuracy of measuring frequency of a radio signal.

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