SU1646064A1 - Method for measuring signal-to-noise ratio and realizing device thereof - Google Patents

Abstract

This invention relates to radio measurements. The purpose of the invention is to improve the measurement accuracy. The essence of the method is that in measuring the signal-to-noise ratio, joint estimates of the signal parameters — the amplitude envelope and the instantaneous frequency values — are used. The device contains a band-pass filter 1, an amplitude detector 2, a frequency detector 3, a multiplier 4, the first and second blocks 5, 7 of averaging, a functional transducer 6, a divider 8. At the inputs of the divider 8, there are two signals. The first is generated using a bandpass filter 1, an amplitude detector 2 and the first averaging unit 5. The second signal is generated by the frequency detector 3, the functional converter 6, the multiplier 4, and the second averaging unit 7. 2 sec. item f-ly, 1 ill.

Description

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The invention relates to radio measurements and can be used to monitor the quality of communication channels in terms of signal-to-noise ratio.

The purpose of the invention is to improve the measurement accuracy.

The drawing shows a structural electrical circuit of a device implementing the proposed method.

The device for measuring the signal-to-noise ratio contains a band-pass filter 1, an amplitude detector 2, a frequency detector 3, a multiplier 4, a first averaging block 5, a functional transducer 6, a second averaging block 7, a divider 8.

The essence of the method is as follows.

The instantaneous values of the frequency w and the amplitude envelope U are estimated.

The measured value of the signal-to-noise ratio h is defined as the average value of the amplitude envelope product and the functional conversion of the instantaneous frequency estimates Y (co), which takes into account the statistical characteristics of the joint estimates of the radio signal. The type of functional transformation can be found from eseni - with respect to Y (ft), an integral equation

Fredholm 1st type: oo oo / / W (U,) (w),

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derived from the expression for the moment of the first order of the two-dimensional function, where W (U, ω, h) is the combined density of the distribution of the envelope of the amplitude and the instantaneous frequency of the radio signal, which can be determined theoretically or experimentally. The implementation of the proposed

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The method allows to measure the signal-to-noise ratio in the presence of a signal, using joint estimates of the radio signal parameters, which eliminates the need to separate the signal and noise components separately, and improves the measurement accuracy.

A device that implements the proposed method works as follows.

The input radio signal, which is a signal-to-noise mixture, enters through a band-pass filter 1, the passband of which is not already the frequency spectrum of the signal, to the amplitude detector

2 and frequency detector 3, where instantaneous envelope values of the amplitude and frequency are estimated. From the output of the amplitude detector 2, the signal is fed to the first input multiply / 1 4 and to the first block 5 of averaging, the output of which is proportional to the average value of the amplitude envelope during the averaging time. The output signal of the frequency detector 3 is fed to the input of the functional converter 6, which converts the Y (w) samples of the instantaneous frequency estimate to determine the signal-to-noise ratio taking into account the statistical properties of the joint distribution of the amplitude envelope and the instantaneous frequency. The type of functional transformation can be obtained by solving the Fredholm integral equation of the first kind using known methods of implementation. In the digital implementation of the frequency detector

3 Functional conversion is carried out in a tabular manner.

The output signal of the functional converter 6 is fed to the second input of the multiplier 4. The products UY (ft) obtained after it depend not only on the estimates of the instantaneous frequency, but also on the amplitude envelope fluctuation, which also carries information about the signal-to-noise ratio, is fed to the second input block 7 averaging. The output signal of the second block 7, the averaging time of which is the same as that of the first block 5 of averaging, is proportional to the average value of the amplitude envelope and the signal-to-noise ratio. The outputs of the second block 7 and the first block 5 are fed to the inputs of the divider 8, where the first signal is divided by the second, and a signal proportional to the signal-to-noise ratio is formed at the output of the divider 8.

Claims (2)

1. A method for measuring a signal-to-noise ratio, including band-pass filtering of an input signal and noise mixture, determining the instantaneous values of the envelope amplitude of the filtered mixture, and dividing the obtained instantaneous values of the amplitude envelope, characterized in that, in order to increase the measurement accuracy, the instantaneous values of the amplitude envelope are averaged, instantaneous values of the frequency of the filtered mixture, determine the joint distribution density of the instantaneous values of the envelope of the amplitude and frequency, followed by averaging, and dividing the averaged instantaneous values of the amplitude envelope are performed by the averaged joint density distribution of the instantaneous values of the envelope of the amplitude and frequency. 2. A device for measuring the signal-to-noise ratio, comprising a divider, a series-connected band-pass filter and an amplitude detector, characterized in that, in order to increase measurement accuracy, the first averaging unit is introduced, the input and output of which are connected respectively to the output of the amplitude detector and the first input of the divider, the serially connected frequency a detector whose input is connected to an output of a bandpass filter, whose input is an input of a device, a functional transducer, a multiplier, a second input of which is connected to an output of an amplitude detector, and a second averaging unit whose output is connected to a second input of a divider whose output is an output of a device . bycod