# The method of determining the energy spectrum of the noise of an electrical signal

The invention relates to the field of hydro-acoustics and radio and can be used to build systems detection signal. The technical result is to reduce the total interference and improve the signal/interference in the determination of the energy spectrum of the noise of the electric signal with a low signal-to-noise ratio of the input electrical noise process. The method of determining the energy spectrum of the noise of the electric signal on the background of normal stationary noise interference contains the discretization electrical noise process, which is a mixture of noise electric signal and a normal stationary noise interference, the set of discretized samples electrical noise process, the fast Fourier transform a given set of discretized samples electrical noise process, the allocation of real and imaginary parts of the energy spectrum; the repetition of the procedures for the allocation of real and imaginary parts of the energy spectrum for n defined sequentially in time of discretized sets of samples electrical noise process, the sum of the real parts of the energy spectrum for n sets, su is the capacity of the energy spectrum for n sets, and the energy spectrum of the noise of the electric signal is defined as the sum of the squares of these amounts. 1 Il.

The invention relates to the field of hydro-acoustics and radio and can be used to build systems detection signal.

Known methods of determining the energy spectrum of electrical noise process, which is a mixture of noise electric signal and a normal stationary noise interference.

Known methods include spectral analysis of this process, the detection of spectral components, the integration of the envelope and the comparison with the threshold (Evtuhov E. C. and Mitko Century B. Examples of engineering calculations in underwater acoustics. Shipbuilding, 1981, S. 77).

Similar to the methods described in the Handbook of underwater acoustics, Shipbuilding, 1988, S. 27. Under spectral analysis see, generally, bandpass filtering, highlighting the main electric energy of a noise process. When using digital technology as a spectral analysis applied procedures of the fast Fourier transform (FFT), which provide the selection and measurement of the energy spectrum of electrical noise process (m of the proposed method is a method of determining the energy spectrum, described in the book Max J. Methods and techniques of signal processing at the physical measurements - M.: Mir, 1983, S. 248.

The method comprises the following sequence of operations: first discretizes the input electrical noise process, and then produce a set of discretized samples of this process and this set is subjected to a fast Fourier transformation. Distinguish the real part of the spectrum, there are the imaginary part of the spectrum; the square of the real part of the spectrum, erected in the square of the imaginary part of the spectrum and the energy spectrum of one set is defined as the sum of the squares of the real and imaginary parts of the spectrum given set of discretized samples of the input electrical noise process.

The determined energy spectrum of a single set of remember and produce the listed operations for determination of the energy spectrum n times for each of the n sets of discretized samples electrical noise process at regular intervals of timet. After that summed obtained energy spectra, the centering of the total energy spectrum, the normalized energy spectrum centered and this electric signal.

The disadvantage of this method is that the increase in the permanent component of accumulated spectrum is not only due to the signal, but due to the interference that at low signal-to-noise ratio reduces the accuracy of determining the energy spectrum of the noise electric signal.

The objective of the invention is to improve the accuracy of determining the energy spectrum of the noise of the electric signal on the background of normal stationary noise noise at low signal-to-noise ratio.

To solve the problem in the method of determining the energy spectrum of the noise of the electric signal on the background of normal stationary noise interference, containing the discretization electrical noise process, which is a mixture of noise electric signal and a normal stationary noise interference, the set of discretized samples electrical noise process, the fast Fourier transform a given set of discretized samples electrical noise process, the selection of the real part of the energy spectrum and the allocation of the imaginary part of the energy spectrum; the same procedure is repeated selection of the real part of the energy spectrum and the imaginary part of energeo electric process, new signs, namely, summed up the real parts of the spectrum for n sets, summed up the imaginary parts of the spectrum for n sets, erected in the square of the sum of the real parts of the energy spectrum for n sets, erected in the square of the sum of the imaginary parts of the energy spectrum for n sets, and the energy spectrum of the noise of the electric signal is defined as the sum of the squares of these amounts.

The technical result from the use of the invention is to reduce the total interference and improve the signal/interference in the determination of the energy spectrum of the noise of the electric signal with a low signal-to-noise ratio of the input electrical noise process.

Explain the achievement of a specific result.

The result of estimation of the power spectrum by the method prototype is a signal defined by the sum of the squares of the n sets the real part and the sum of the squares of the n sets the imaginary part of the energy spectrum. This is equivalent to the process of detecting, when the real part and the imaginary part of the AC input voltage occurs only positive voltage real part and imaginary part, which is erected in the square, scladina the energy imaginary part of the AC input voltage.

It is known that the real part of each spectral component and the imaginary part of the same spectral component consists of positive and negative values.

With standard processing, when calculate the energy of the spectral component within a set of positive and negative values of the square.

The accumulation of n successive sets of input spectra of the sample process is the sum of positive values of energy and noise, and signal.

In the proposed procedure for determining the energy spectrum is the sum of positive and negative values of the real and imaginary values of the spectral counts of the n sets of input discrete process.

Because of the number of spectral counts interference for the 1st, 2nd, etc. sets do not coincide due to the fact that they are not correlated, it may be a coincidence of positive values of one spectral counts of the interference is the sum of the negative values of other spectral counts of the interference of different sets and their mutual subtraction as for the real parts and the imaginary parts of the total energy spectrum interference. In the result of this processing is happening along the frequency axis is determined, when the summation of discretized sets of samples is the addition of the positive and negative values of the spectral samples of the signal in different sets and after squaring these amounts to increase the signal energy.

Thus, accumulation of the n sets in the proposed method increases the signal-to-interference and by increasing the signal energy, and by reducing energy interference.

The drawing shows a block diagram of a device implementing this method. The device comprises discriminator input signal 1, the spectrum analyzer 2, executed on the processor fast Fourier transform (FFT), which has two outputs, one of which is connected to the block 3 calculate the real part of the spectrum, the second - unit 4 calculate the imaginary part of the spectrum; the output of each of them is connected through the block 5 summation of the real part of the spectrum and block 6 summing the imaginary part of the spectrum with Quad 7 and 8, and outputs Quad is connected to the adder 9.

Using the above device, the proposed method is implemented as follows.

Input voltage is supplied to discriminator 1, where the discretization of the input noise signal and the set of discretized samples. Once received at the input unit 2 spectroanalyzer FFT.

From the output of block 2 FFT are given separately positive and negative values of the real part of the spectrum Re - block 3, and separately the positive and negative values of the imaginary part of Jm spectrum block 4, which are summarized in blocks 5 and 6.

The results of the summationandserved in blocks squaring 7 and 8, the output of which signals are formedand; next, in block 9, a signal is generated representing the energy spectrum of the noise electric signal

in this case, as was shown earlier, the signal energy increases, and the energy of the interference is reduced, which makes the task of the invention is solved.

Claims

The method of determining the energy spectrum of the noise of the electric signal on the background of normal stationary noise interference, containing the discretization electrical noise process, which is a mixture of noise electric signal and a normal stationary noise interference, the set of discretized samples electrical noise process, fast into the second part of the energy spectrum and the allocation of the imaginary part of the energy spectrum, repetition of the procedure of selection of the real part of the energy spectrum and the imaginary part of the energy spectrum for n defined sequentially in time of discretized sets of samples electrical noise process, characterized in that summed up the real parts of the energy spectrum for n sets, summed up the imaginary parts of the energy spectrum for n sets, erected in the square of the sum of the real parts of the energy spectrum for n sets, erected in the square of the sum of the imaginary parts of the energy spectrum for n sets, and the energy spectrum of the noise of the electric signal is defined as the sum of the squares of these amounts.

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