# Method of assessment frequency distortion (options)

The method relates to the field of radio and can be used to measure the level of frequency distortion of a two-port, such as audio amplifiers. According to the method of forming voltage, the instantaneous value of which is determined by the value of the normalized amplitude-frequency characteristics of the quadrupole. Then this voltage decrease per unit or logarithmic. From the obtained voltage allocate its absolute value and integrate within its validity. Quantitative assessment criterion frequency distortion is the square of the frequency distortion resulting from the integration. The method aims at improving the informativeness evaluation of frequency distortion of a quadrupole in the original signal. 2 S. p. f-crystals, 1 Il.

The invention relates to the field of radio and can be used when building level meters frequency distortion of a two-port, such as audio amplifiers.

Adopted as the prototype of the classical method of estimating frequency distortion, consisting in the definition of the normalized amplitude-frequency characteristics (AFC) Y(_{0}) - gain on certain average frequency_{0}), measured at specific points in the frequency response may not be a measure introduced distortion. Distortion of the signal spectrum �"https://img.russianpatents.com/chr/969.gif" border="0">_{i}for which It has been established that(_{i}has at this point the minimum or maximum value, and depend on the type of the function K(), which shows how changing the entire amplitude range of the signal after passing through the investigated quadrupole.

Technical result achieved when using the present invention is to improve the informativeness evaluation of frequency distortion of a quadrupole in the original signal.

The technical result is achieved in that in the method of estimating frequency distortion (option 1) quadrupole consisting in the definition of the normalized amplitude-frequency characteristics of the quadrupole and generating the output voltage, the instantaneous value of which is determined by the value of the normalized amplitude-frequency characteristics according to the invention the output voltage is reduced by one unit, then from the obtained voltage allocate its absolute value and the received voltage is integrated into the limits of its validity, the assessment of the frequency distortion is the measured value of the voltage after the integration.

The technical result is achieved by Thu plitude-frequency characteristics of the quadrupole and generating the output voltage, instantaneous value of which is determined by the value of the normalized amplitude-frequency characteristics according to the invention the output voltage logarithmic, then from the obtained voltage allocate its absolute value and the received voltage is integrated into the limits of its validity, the assessment of the frequency distortion is the measured value of the voltage after the integration.

The invention is illustrated graphic material. The drawing shows graphs illustrating the method according to the first embodiment. The drawing contains a graph of the normalized frequency response Y() representing an example of the frequency response of the amplifier of audio frequencies; a constant level Y(_{0})=1, is equal to the relative strengthening on average frequency_{0}and represents the ideal frequency response; a graph of the magnitude |Y()-1|.

As the rate of insertion frequency distortions of the adopted functional(Y()) that determines the distance between the compared values Y() and Y(_{0})=1:

The physical essence(Y()) it is easy to understand if you refer to the drawing. The total area of the shaded plots of the function Y(), selected with respect to a perfect medium level Y(_{0}), is numerically equal to the value of the functional(Y()) that is supposed to take into account the whole set of frequency distortion, dependent on both the size of the range [_{1};_{2}] so and by how much it deviated from the level Y(_{0})=1. For practical calculations of the values of(Y()) with known mean Y() it is convenient to calculate the integral of the modulus of the difference Y(and constant level Y(_{0}), as shown in expression (1). This sets the sequence of actions on the primary signal necessary to obtain estimates(Y()). If the primary �="https://img.russianpatents.com/chr/969.gif" border="0">as the scan time, to assess the level of frequency distortion should be reduced by one unit, then select the absolute value obtained from the difference and continue to integrate within steps of this signal [t_{1}; t_{2}]:

Methods of obtaining values Y(t), repeating the shape of the curve Y(), widely known and simplicity of implementation. For example, when connecting the output of the sweep generator to the input of the investigated two-port network, the output of which is connected to the input of the amplitude demodulator will receive the probe response, the output voltage which is the output voltage of the demodulator will determine the form of response in a certain scale. To obtain at the output of the demodulator normalized values Y(t) the output signal of the quadrupole must be scaled (to weaken or strengthen) so that at a frequency of_{0}his total gain(_{0}) would be one, and then

therefore, additionally to perform the division operation for the above s-sweep generator.

The second variant of the method of estimating frequency distortion differs from the first by the fact that the signal Y(or it displays Y(t) to integrate logarithmorum. Assessment criterion in this case is functional

The operation taking the logarithm eliminates the need for calculating the difference in paginegialle expression and, in addition, allows to Express the result in the conventional units relative gain - dB.

By analogy with the applied theory amplifiers term is the square of the gain functions, we Express (1) and (2) could be considered as the square of frequency distortion. The minimum distortion must meet at least these functionals, and the condition(Y())=0 corresponds to the ideal situation of complete lack of frequency distortion.

Measuring the area of a frequency distortion, for example, audio amplifiers in contrast to the standard evaluation of the uneven frequency response enables you to not give a formal evaluation of the frequency response deviations from the ideal, and to obtain a quantitative measure associated with psychophysiological features of auditory perception. Total account is the shaft distortion with their objective technical assessment, measured as the value of the functional(Y()). Moreover, it should be emphasized that the frequency dependence of the distortion on the width of the bands for which Y()1, installed long enough [Glukhov A. A. fundamentals of sound broadcasting. M: Communications, 1977, pages 38-39] and it is known that if a relatively wide spectral band dips or rises response will result in corresponding subjective feelings already at the level of 5 dB, the narrow peaks and dips even at the level of 15 dB may not always be noticeable to the ear.

Claims

1. Method of assessment frequency distortions of the quadrupole, consisting in the definition of the normalized amplitude-frequency characteristics of the quadrupole and generating the output voltage, the instantaneous value of which is determined by the value of the normalized amplitude-frequency characteristics, wherein the output voltage is reduced by one unit, then from the results of the emit its absolute value and the received voltage is integrated into the limits of its validity, the assessment of the frequency distortion is the measured voltage value after Inoi amplitude-frequency characteristics of the quadrupole and generating the output voltage, instantaneous value of which is determined by the value of the normalized amplitude-frequency characteristics, characterized in that the output voltage logarithmic, then from the obtained voltage allocate its absolute value and the received voltage is integrated into the limits of its validity, the assessment of the frequency distortion is the measured value of the voltage after the integration.

**Same patents:**

FIELD: measurement technology.

SUBSTANCE: analyzer can be used for measuring level of frequency distortions introduced by audio channel. Analyzer has two spectrum analyzers which are used to determine signal spectra at output and input of tested four-terminal network. Input and output signal spectra are subject to normalization and are introduced into subtraction unit and later to unit for determining normalized signals difference module. Signal from unit for determining module is sent to integrator to find end value, which characterizes area of frequency distortions introduced by four-terminal network. According to another version of analyzer the module is substituted by squarer. Analysis of frequency characteristics can be performed without turning four-terminal network into special measuring mode.

EFFECT: improved truth of information; increased precision of measurement.

2 cl, 3 dwg