New principle of direct signal-to-noise ratio measurement

The sensitivity of radio receiving devices and systems used in all areas of practical applications of electronics is determined at a certain signal-to-noise ratio value. Examples of systems for which this ratio is one of the important quality indicators are given. The objective of the research is to solve the current problem of measuring the signal-to-noise ratio in a wide frequency range, simplify the requirements for measuring instruments, and improve their technical and metrological characteristics. The new principle of measuring the signal-to-noise ratio, which consists in establishing precise connections between this ratio and the parameters of noise amplitude, phase, and frequency signal modulation, is theoretically justified. The validity of using modulation meters as signal-to-noise ratio meters without changing the operation mode has been proven. At that, the signal and noise are not separated and are not measured separately. Precise connections ensure the absence of methodological measurement errors. There are three options for implementing the developed measurement principle using one industrial device (modulation meter) and providing a direct reading of the signal-to-noise ratio. In two of these options there are no restrictions on the origin and type of noise, it may be arbitrary. Taking into account the unambiguous connection between phase and frequency modulation, all options for implementing the considered principle were experimentally tested. The discrepancies between the measurement results and the initial data of the signal and noise generator are within the error limits of the generator instruments. Mathematical simulation of the developed principle for measuring the signal-to-noise ratio in the Mathcad software package has been carried out, and recommendations for using the principle have been given. The fundamental advantages of the proposed principle are its simple implementation using a single industrial device and metrological support for measuring the signal-to-noise ratio. This mode coincides with the main modulation measurement mode. Metrological support for the signal-to-noise ratio measurement mode is carried out within the framework of existing state verification plans. The main technical and metrological characteristics of signal-to-noise ratio meters obtained by applying the considered principle are determined by the parameters of existing modulation meters, i.e. a wide (up to 26 GHz) frequency range and a low (10–20%) measurement error.