RU2615016C2 - Device for measuring auditory-adapted harmonic distortions of electrical signal - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: device comprises a generator of the harmonic oscillations, an input and an output terminal for connecting the measurement object, an adjustable unit of equalizing the signal levels, the first and the second display units, the first and the second differentiating units, five switches, a frequency processing unit, a comparator, a bandpass filter, a high-pass filter tunable by frequency, a low-pass filter tunable by frequency and level, a two-position switch, a control-and-measuring unit. Wherein the first and the second display units are identical to each other, the first and the second differentiating units are identical to each other and are rearranged simultaneously, and the high-pass and the low-pass filters are arranged simultaneously by frequency . In the frequency processing unit, the high-pass and the low-pass filters are connected in series one after the other and are shunted each by its switch, the fourth and the fifth one, respectively. The two-position switch is inserted between the frequency processing unit and the control-and-measuring unit, allowing to connect the input of the control-and-measuring unit either to the output of the low-pass filter, or to the output of the comparator.

EFFECT: expanding the functional capabilities of the device.

1 dwg

Description

Technical field

The invention relates to the field of instrumentation and is intended for measuring harmonic distortion of an electrical signal of sound frequency introduced by sound equipment, in particular sound amplifying equipment.

The purpose of the invention is the expansion of the functionality of the device.

This is achieved by introducing the possibility of a separate assessment of the intensity of the first harmonic of the distorted signal and the intensities of its higher harmonics, not adapted or adapted to the auditory perception of distortions after weighing them and (or) reducing the psychoacoustic redundancy caused by frequency masking, for which high-pass and low-pass filters are shunted by each a switch, the fourth and fifth, respectively, and between the frequency processing unit and the control and measuring unit is entered on-off a switch that allows to connect the input of the control and measuring unit or to the output of the low pass filter or to the output of the comparator.

Description of analog

A device for measuring harmonic distortion of an electrical signal and its derivatives, comprising an input and an output terminal for connecting a measurement object, a harmonic oscillator, the output of which is connected to an input terminal, an adjustable level signal leveling unit connected in series, the first and second identical and simultaneously tunable differentiation units, each of which is shunted by a separate switch, the first and second, respectively, and control nn-measuring unit, as well as identical first and second display units, the input of the first display unit is connected to the output of the signal leveling unit, and the input of the second display unit is connected to the output of the second differentiation unit [1].

The known device allows objective measurements taking into account subjective factors such as increasing the sensitivity of auditory perception to high-order nonlinearity products, for which either the first or second derivative of the distorted signal is obtained, obtained by hardware single or double differentiation, respectively. However, the measurement procedure does not take into account such a property of hearing as masking in the frequency domain, and in particular, masking with a tonal signal, which is the main harmonic of the distorted signal with respect to its higher harmonics when a harmonic signal is input to the measurement object.

Prototype description

A device for measuring harmonic distortion of an electric signal is known, comprising an input and an output terminal for connecting a measurement object, a harmonic oscillator, the output of which is connected to an input terminal, an adjustable level signal leveling unit, the first and second identical and simultaneously tunable blocks are connected in series to the output terminal differentiation, each of which is shunted by a separate switch, the first and second, respectively, the frequency processing unit, s shunted by the third switch, and the control and measuring unit, the device also contains identical first and second display units, the input of the first display unit is connected to the output of the signal leveling unit, and the input of the second display unit is connected to the output of the second differentiation unit, while the frequency processing unit includes a comparison unit and a band-pass filter, consisting of a series-tunable high-pass filter that is tunable in frequency and a filter that is tunable in level and frequency and the low-pass, the input of the band-pass filter formed by the input of the high-pass filter is connected to the first input of the comparison unit, and the output of the band-pass filter formed by the output of the low-pass filter is connected to the second input of the comparison unit, the connection of the input of the high-pass filter and the first input of the comparison unit forms the input of the frequency processing block, the output of this block forms the output of the comparison block [2, p. 3 files].

The device implements the possibilities of methods of objective measurement of distortion, taking into account not only such properties of hearing as the aggravating effect of higher-order nonlinearity products on the perception of distortion, but also the properties of auditory frequency masking of higher harmonics by a fundamental signal. This is achieved by affecting the spectrum of the distorted signal. Firstly, by weighing the amplitudes of the higher harmonics in proportion to their ordinal number or its square, for which a differentiation operation is performed before evaluating their intensities, performed once or twice. Secondly, by introducing a reduction in the psychoacoustic redundancy of the distorted signal by formally matching the intensities of the higher harmonics with a quantitative measure of their frequency masking during auditory perception, for which, before evaluating the intensities of the higher harmonics, they decrease by an amount equal to the increase in the curve of the threshold of hearing at their respective frequencies in the presence of masking signal with a fundamental frequency [2, FIG. one].

Using the known device, it is possible to determine such total and partial distortion factors as harmonic coefficients, weighted harmonic coefficients, doubly weighted harmonics coefficients, masked harmonics coefficients, masked and weighted harmonics coefficients, masked and double weighted harmonics coefficients. The listed coefficients reflect a quantitative assessment of the harmonic distortions of the electrical signal that are not adapted or to varying degrees adapted to the auditory perception, i.e. hearing-adjusted harmonic distortion.

Prototype criticism

The reasons that impede the achievement of the required technical result when using the known device adopted as a prototype include the lack of the ability to separate assess the intensity of the first harmonic of the distorted signal and the intensities of its higher harmonics that are not adapted or adapted to an auditory perception of distortions. The introduction of such capabilities will significantly simplify the measurement procedure.

SUMMARY OF THE INVENTION

The problem to which the invention is directed, is to expand the functionality of the device.

This problem is solved by achieving a technical result in the implementation of the invention, which consists in introducing the possibility of a separate assessment of the intensity of the first harmonic of the distorted signal and the intensities of its higher harmonics that are not adapted or adapted to the auditory perception of distortions after weighing them and (or) reducing psychoacoustic redundancy due to frequency masking.

The specified technical result in the implementation of the invention is achieved by the fact that the high and low frequency filters are shunted by each switch, the fourth and fifth, respectively, and a two-position switch is inserted between the frequency processing unit and the control and measurement unit, which allows you to connect the input of the control and measurement unit, or to the output of the low-pass filter, or the output of the comparison unit.

The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information, made it possible to establish that the applicant did not find analogues characterized by features identical to all the essential features of the claimed invention, and the identification of the prototype from the identified analogues as the closest in combination of features allowed determine the set of essential in relation to the technical result of the features in the claimed invention set forth in the claims.

Therefore, the claimed invention meets the requirement of "novelty" of the current legislation.

To verify the conformity of the claimed invention to the requirements of the inventive step, the applicant conducted an additional search for known solutions in order to identify features that match the features that are distinctive from the prototype, the results of which showed that the claimed invention does not explicitly follow from the prior art, since the prior art defined by the applicant, the effect of the transformations provided for by the essential features of the claimed invention on the achievement of technical result.

Therefore, the claimed invention meets the requirement of "inventive step" of the current legislation.

List of drawings

The drawing shows a structural diagram of the device, where 1 is a generator of harmonic oscillations; 2 - input terminal; 3 - measurement object; 4 - output terminal; 5 - adjustable block alignment of signal levels; 6 - the first display unit; 7 - the first differentiation unit, 8 - the first switch; 9 - the second block of differentiation; 10 - second switch; 11 - second display unit; 12 - block frequency processing; 13 - the third switch; 14 is a block comparison; 15 - band-pass filter; 16 - tunable high-pass filter; 17 - tunable in level and frequency low-pass filter; 18 - the fourth switch; 19 - fifth switch: 20 - on-off switch; 21 is a control and measuring unit. In this case, the first 6 and second 11 display units are identical to each other, the first 7 and second 9 differentiation units are identical to each other and are tuned simultaneously, and the filters of the upper 16 and lower 17 frequencies are tuned in frequency at the same time.

Information confirming the possibility of carrying out the invention

Information confirming the possibility of carrying out the invention with the receipt of the specified technical result are as follows.

The proposed device, the structural diagram of which is shown in the drawing, implements transformations that allow you to adapt the values of the intensities of the higher harmonics to their auditory perception. This is done, firstly, by performing a conversion that increases the intensity of each higher harmonic in proportion to its number or the square of its number, by hardware differentiation or double hardware differentiation, respectively. Secondly, due to the frequency processing, which reduces the psychoacoustic redundancy of the signal, due to the phenomenon of frequency masking of higher harmonics by a tonal signal, the role of which is the first harmonic.

The device contains input 2 and output 4 terminals for connecting an object of 3 measurements, a harmonic oscillation generator 1, the output of which is connected to an input 2 terminal, an adjustable signal leveling adjustment unit 5 connected in series to the output 4 terminal, the first 7 and second 9 identical and simultaneously tunable differentiation units, each of which is shunted by a separate switch, the first 8 and second 10, respectively, the frequency processing unit 12, shunted by the third switch 13, and control ln block 21, the device also contains identical first 6 and second 11 display units, the input of the first display unit 6 is connected to the output of the signal leveling unit 5, and the input of the second display unit 11 is connected to the output of the second differentiation unit 9, while the frequency unit 12 the processing includes a comparison unit 14 and a band-pass filter 15, consisting of a series-tunable high-pass filter 16 and a tunable-level and frequency low-pass filter 17, the input of the band-pass filter 15 formed by the input of the highpass filter 16 is connected to the first input of the comparison unit 14, and the output of the bandpass filter 15 formed by the output of the lowpass filter 17 is connected to the second input of the comparison unit 14, the connection of the input of the highpass filter 16 and the first input of the comparison unit 14 forms the input of the frequency processing unit 12, the output of this unit 12 forms the output of the comparison unit 14, in addition, the filters of the upper 16 and lower 17 frequencies are each shunted by their own switch, the fourth 18 and fifth 19, respectively, and between the frequency processing unit 12 Ki and control unit 21 is a two-position switch 20, which allows you to connect the input of the control unit 21 either to the output of the low-pass filter 17, or to the output of the comparison unit 14.

Introduced circuit elements of the proposed device are the fourth 18 and fifth 19 switches and on-off switch 20.

The device works as follows. The inclusion in the measuring path using the appropriate switches (8 and 10) of only the first block 7 or both of the differentiation blocks 7 and 9 allows the operation of weighing the amplitudes of the higher harmonics to be proportional to the number of these harmonics or the square of their number, which adapts them to the hearing perception of the higher harmonics of the distorted signal . In this case, using measuring instruments included in the control and measuring unit 21, it is possible to measure such harmonic distortion factors as the total and (or) partial coefficients of weighted harmonics, total and (or) partial coefficients of doubly weighted harmonics. Without performing the differentiation operation, the standardized total and / or partial harmonic coefficients are measured.

Block 5 alignment of signal levels, as well as the first 6 and second 11 display units provide a reduction in the methodological errors of the measurements that are inevitable when performing hardware differentiation.

The frequency processing unit 12, shunted by the third switch 13, is connected by its input to the output of the second 9 differentiation unit. Block 12 performs the operation of changing the intensities of the higher harmonics in accordance with the rise of the curve of the threshold of audibility, thereby increasing the degree of correlation of objective and subjective assessments of the quality of sound transmission [2]. The presence of block 12 allows using measuring instruments included in the control and measuring block 21 to evaluate a number of harmonic distortion coefficients: the total and (or) partial coefficients of masked harmonics (when both differentiation blocks 7 and 9 are disconnected from the circuit), total and (or ) partial coefficients of masked and weighted harmonics (when connecting the first block 7 differentiation), the total and (or) partial coefficients of masked and double-weighted harmonics (when connecting both blocks 7 and 9 diff conference).

The frequency processing unit 12 comprises a comparison unit 14 and a band-pass filter 15, consisting of a series-connected high-pass filter 16 and a low-pass filter 17. The input of the band-pass filter 15 formed by the input of the high-pass filter 16 is connected to the first input of the comparison unit 14. The output of the band-pass filter 15, formed by the output of the low-pass filter 17, is connected to the second input of the comparison unit 14. The input of block 12 forms a connection between the input of the high-pass filter 16 and the first input of the comparison block 14, while the input of block 12 is connected to the output of the second differentiation block 9. The output of block 12 forms the output of block 14 of comparison. Filters 16 and 17 are tuned in frequency simultaneously. Such a tuning of the filters will be required when changing the frequency of the test harmonic signal generated by the generator 1 harmonic oscillations. Only the low-pass filter 17 needs adjustment in level. Such a restructuring will be required during measurements, the conditions of which provide for other levels of listening to audio programs using object 3 measurements.

The input signal of the frequency processing unit 12 and the output signal of the band-pass filter 15 are fed to the different inputs of the comparison unit 14, which subtracts from the distorted signal that part of it that will be masked by the frequency properties of the hearing, thereby reducing the psycho-acoustic redundancy of this signal. Next, the output signal of the comparison unit 14 is subjected to qualitative and quantitative analysis using devices included in the control and measuring unit 21. The on-off switch 20 is connected to the output of the low-pass filter 17 by one of the fixed contacts of its electric circuit and the output of the comparison unit 14 by the other. The movable contact of the electrical circuit of the switch 20 is connected to the input of the control and measuring unit 21.

To ensure the assessment of various harmonic distortion coefficients, the lower position of the movable contact of the switch 20 will be required, which will allow you to connect the stationary contact with the movable contact connected to the output of the comparison unit 14. The control and measuring unit 21 may include an oscilloscope, a frequency-selective voltmeter and (or) an industrial harmonic distortion meter. Also, the control and measuring unit 21 may contain other measuring devices that allow you to isolate and evaluate the intensity of each of the harmonics and to calculate by calculation the total and (or) partial harmonic distortion coefficients that are not adapted or adapted to auditory perception to different degrees. The total coefficients of various types can also be determined directly using a harmonic distortion meter.

The presence of a high-pass filter 16 in the measurement circuit eliminates the fundamental harmonic with the frequency of the test harmonic signal from the distorted signal, leaving only non-linear products. The inclusion of the high-pass filter 16 precisely at the input of the band-pass filter 15 also ensures the elimination of low-frequency noise from the signal (noise, interference, background frequency, a multiple of the frequency of the industrial network, etc.), which increases the reliability of the measurement results by reducing the value of the hardware error.

The presence in the measurement circuit of the low-pass filter 17, following the high-pass filter 16, ensures that the band-pass filter 15 passes only the distortion products that fall into the masking zone, while only those parts of the higher harmonics intensities that are located below the curve of the auditory threshold pass through the filter 17, which means they will be masked by a person’s hearing. This will allow you to subtract these masked parts of the intensities of each higher harmonic from the entire distorted signal supplied to the input of the frequency processing unit 12 when applying the output signal of the band-pass filter 15 to the second input of the comparison unit 14.

These transformations in the inventive device can significantly simplify the measuring procedure. Consider the options for implementing a simplified measurement procedure in the presence in the control and measuring unit 21 only of the oscilloscope and the voltmeter of the rms values to observe the nature and fix the rms values of the signals.

1. With the open positions of both switches 18 and 19:

- at the upper position of the movable contact of the on-off switch 20, this contact is connected to a fixed contact connected to the output of the low-pass filter 17, which allows you to connect the control and measuring unit 21 to the output of this filter 17 and measure the intensities of the higher harmonics in the masking zone, those. measurement of inaudible parts of intensities of higher harmonics;

- at the lower position of the movable contact of the on-off switch 20, it is connected to the fixed contact connected to the output of the comparison unit 14, which allows you to connect the control and measuring unit 21 to the output of this unit 14 and measure the intensities of the first harmonic and distortion products, with removed psychoacoustic redundancy and to one degree or another weighted, which depends on the positions of the switches 8 and 10.

2. With the closed position of the switch 18 and the open position of the switch 19:

at the upper position of the movable contact of the on-off switch 20, the intensities of the first harmonic and higher harmonics located in the masking zone (inaudible parts of the intensities) are measured;

- at the lower position of the movable contact of the on-off switch 20, the intensities of the distortion products are measured with the removal of psychoacoustic redundancy and to some extent weighted, which depends on the positions of the switches 8 and 10.

3. With the open position of the switch 18 and the closed position of the switch 19:

- at the upper position of the movable contact of the on-off switch 20, the intensities of the higher harmonics are measured, to some extent weighed, which depends on the positions of the switches 8 and 10;

- at the lower position of the movable contact of the on-off switch 20, the intensity of the first harmonic is measured.

4. With the closed positions of both switches 18 and 19:

- at the upper position of the movable contact of the on-off switch 20, the intensities of the first harmonic and higher harmonics are measured, to a greater or lesser extent weighted, which depends on the positions of the switches 8 and 10;

- at the lower position of the movable contact of the on-off switch 20, the intensities of the first harmonic and higher harmonics are measured, to some extent weighted, i.e. the same as with the upper position of the movable contact.

The simple manipulations listed above allow using known formulas to carry out calculations and determine the total harmonic coefficients: unweighted and masked, weighted and masked, twice weighted and masked. Moreover, the formulas for calculating the coefficients are the same: this is the ratio of the rms value of the distortion products to the rms value of the entire signal. These coefficients can be determined even if the control and measuring unit 21 contains only an oscilloscope and a rms voltmeter. The measuring procedure is reduced to fixing the voltage values on the voltmeter scale with the open position of the switch 19 and the lower position of the movable contact of the on-off switch 20 for two positions of the switch 18. Then it remains to calculate the ratio of these values. If you want to determine the values of the distortion coefficients as the ratio of the rms value of the distortion products to the value of the undistorted signal (to the value of the first harmonic), you should set the movable contact of the on-off switch 20 to the lower position, close the switch 19 and open the switch 18. This will ensure the measurement of the intensity value of the first harmonic of the signal .

Thus, the claimed device allows you to qualitatively and quantitatively evaluate the harmonic distortion of not only the complete signal that has undergone these or other types of processing, but also separately evaluate the different parts of its spectrum: highlight either the first harmonic or higher harmonics, the amplitudes of which are adapted to the auditory to different degrees hearing perception of nonlinear distortions: not adapted or adapted by weighing them and (or) reducing psychoacoustic redundancy due to frequency masking.

The introduced capabilities make it possible to significantly simplify the measurement procedure, which means reducing the laboriousness of measurements made to quickly evaluate the effectiveness of circuitry solutions aimed at reducing the nonlinear distortions introduced by the sound technical device acting as the measurement object. The simplification of the measurement procedure is explained by the possibility of using only an oscilloscope and a rms voltmeter from the entire fleet of measuring equipment, which may contain a control and measuring unit.

The expansion of the functionality of the known device is achieved by acquiring the properties of changing inter-unit communications by means of two switches 18 and 19, shunting the filters of the upper 16 and lower 17 frequencies, as well as the on-off switch 20 connected between the frequency processing unit 12 and the measuring and measuring unit 21.

The above information indicates the fulfillment of the following conditions when using the claimed invention:

- a device embodying the claimed invention in its implementation is intended for use in instrumentation for detecting and evaluating harmonic distortions of the sound frequency signal introduced by sound equipment, in particular sound reinforcement equipment;

- for the claimed invention in the form described in the claims, the possibility of its implementation using the methods described above or known before the priority date of the funds is confirmed;

- a device embodying the claimed invention in its implementation, is capable of achieving the specified technical result.

Therefore, the claimed invention meets the requirement of "industrial applicability" under applicable law.

Literature

1. Patent for the invention 2456624 (RU 2456624 C1) of the Russian Federation, IPC G01R 23/20 (2006.01). A device for measuring harmonic distortion of an electrical signal and its derivatives [Text] / Tikhonova L.S .; Applicant and patent holder St. Petersburg State University of Cinema and Television. - No.2010145565 / 28, 11/09/2010. Published: July 20, 2012, Bulletin No. 20.

2. Patent for the invention 2547166 (RU 2 547 166 C1) of the Russian Federation, IPC G01R 23/20 (2006.01). A method for measuring harmonic distortion of an electrical signal (options) and a device for its implementation [Text] / Tikhonova L.S .; Applicant and patent holder St. Petersburg State University of Cinema and Television. - No. 2013147204/28, 10.22.2013. Published: 04/10/2015, Bulletin No. 10 (p. 3 f-ly - prototype).

Claims (1)

A device for measuring sound-adapted harmonic distortions of an electrical signal, containing input and output terminals for connecting the measuring object, a harmonic oscillator, the output of which is connected to the input terminal, an adjustable level signal leveling unit, the first and second identical and simultaneously tunable blocks are connected in series to the output terminal differentiation, each of which is shunted by a separate switch, the first and second, respectively, the frequency block processing, shunted by the third switch, and the control and measuring unit, the device also contains identical first and second display units, and the input of the first display unit is connected to the output of the signal leveling unit, and the input of the second display unit is connected to the output of the second differentiation unit, while The frequency processing includes a comparison unit and a band-pass filter, consisting of a series-tunable high-pass filter that is tunable in frequency and tunable in level and frequency low-pass filter totem, the input of the bandpass filter formed by the input of the highpass filter is connected to the first input of the comparison unit, and the output of the bandpass filter formed by the output of the lowpass filter is connected to the second input of the comparison unit, connecting the input of the highpass filter and the first input of the comparison unit forms the input of the frequency processing unit, the output of this block forms the output of the comparison unit, moreover, the high and low frequency filters are tuned in frequency at the same time, characterized in that the upper and lower filters The lower frequencies are each shunted by their own switch, the fourth and fifth, respectively, and a two-position switch is inserted between the frequency processing unit and the control and measurement unit, allowing you to connect the input of the control and measurement unit either to the output of the low-pass filter or to the output of the comparison unit.

Images