SU1654983A1 - Adaptive device for suppressing acoustic self-excitation - Google Patents

Abstract

This invention relates to electrical communication and sound amplification. The purpose of the invention is to simplify the device and eliminate the magnitude of regenerative and multiplicative distortion. The device contains serially connected compensator of regenerative and multiplicative distortions and a frequency shift block. The compensator is made in the form of a digital adaptive filter, which is automatically rebuilt according to the results of periodically produced spectral analysis of the input signal. This eliminates regenerative and multiplicative distortions, and thus increases syllable intelligibility while maintaining the stability margin of the reinforcement tract. 2 Il.

Description

The invention relates to a technique of electrical communication and can be used, in particular, in a sound engineering, for example, in devices for amplifying audio signals.

The purpose of the invention is to simplify the design of the device and increase the depth of suppression of reflected signals by eliminating regenerative and multiplicative distortions.

FIG. 1 shows a functional diagram of an adaptive device; in fig. 2 is a diagram explaining its operation.

The adaptive acoustic self-excitation suppressor (Fig. 1) includes a series-connected compensator 1 of multiplicative and regenerative distortions and a frequency shift unit 2. Compensator 1 is made in the form of a digital adaptive filter and contains ADC 3, the output of which through the first switch 4 is connected to the first 5 and second 6 accumulators of the input signal, connected through the second switch 7 to the input of the correlation function counting unit 8 and the signal input of unit 9 adaptive filtering, to the control, the input of which through the block 10 for calculating filter coefficients, connects the output of block 8 for calculating samples of the correlation function. The output of block 9 is connected via the third switch 11 to the third 12 and fourth 13 accumulators of filtered signal samples connected via the fourth switch 14 to the input of the DAC 15, the output of which is the output of the compensator 1. The control inputs of the switches 4, 7, 11 and 14 are connected with the output of the control unit 16.

When included in the sound amplifying system, the adaptive acoustic self-excitation suppression device works as follows.

When the audio signal x (t) is applied to the microphone, the latter is amplified by a microphone amplifier and after processing in the AOC suppression device (where it is digitized,

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filtering, restoration to analog form and frequency shift) is fed to a power amplifier, and then radiated by a thunder coaxial speaker. The emitted signal through the acoustic feedback circuit (as a result of the Direct sound transmission or as a result of multiple reflections from the room boundaries) returns to the microphone, which can lead to acoustic self-excitation.

The compensator works as follows.

The audio signal x (t) from the microphone amplifier enters the ADC 3, where it converts into digital samples x (n). If the control inputs of the switches 4, 7, 11 and 14 from the switch control control unit 16 receive a high potential, then the number

counts (to - time to record the selection i

Rock in the drive, equal to the switch switching time):

x (ZUU-H), x (3N + 2), ..., Jc (4 / V), the input signal x (t) through the first switch 4 is accumulated and stored in the first accumulator 5 input samples. Simultaneously forming an array of N samples in the first accumulator 5 / V of the previous samples

x (2N +), x (2N + 2), ..., x (3N) of the input signal from an array of N samples stored in the second accumulator 6 and received in the previous operation cycle of block 16 (when the potential at the control inputs of the switches 4 , 7, 11, and 14 is low), through switch 7, are read into the input of block 8 of the calculation of samples of the correlation function.

signal y (t), which is the output signal of the compensator 1.

After the switches 4, 7, 11, and 14 from the output of block 16 in the next cycle of operation, low potential is applied (Fig. 2), 5 accumulation of successive arrays of N input samples

(4JV + 1), x (), ..., x (5N) and L / filtered samples

0 (DRC-1), “/ (DRC-2), ..., y (4N) 10 occurs in the second 6 and fourth 13 accumulators, respectively, and the next N input samples are read

(SLCH-1), x (SSCH-2), .... (4LO for filtering and N filtered samples

y (2N +), y (2N + 2) y (3N)

for feeding to the DAC 15, respectively, occurs from the first 5 and third 12 accumulators of input and filtered signals.

Thus, in the compensator 1 of the adaptive device for suppressing acoustic self-excitation, periodically (once per t0 s), coefficients are calculated for the adaptive filtering unit 9, according to

analysis of a sample of 25

samples of the input signal x (t) and in accordance with the calculated coefficients it is filtered.

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Claims (1)

Invention Formula An adaptive acoustic self-excitation suppressor comprising a series-connected distortion compensator and a frequency shift unit, characterized in that, in order to simplify the devices — correlation function counts, alignment, and increase the suppression depth the numerical value in block 8 is entered into block 10 for calculating filter coefficients, where the values of filter coefficients are calculated from them, which are then entered into block 9 of adaptive filtering. In block 9, the N filtered samples are calculated according to the calculated coefficients: y (2N +), y (2N + 2), .... “/ (EVIL, which accumulate through switch 11 reflected signals by eliminating regenerative and multiplicative distortions, the compensator contains an analog-to-digital converter, the output of which is supplied by the first switch, the outputs of which are connected to the first and second drives connected through the second switch to the first input of the adaptive filtering unit and the input of the sample calculation unit correlation function, output is stored and stored in the third accumulator through the coefficient calculation unit le 12. At the same time filtered samples: y (N + l), y (N + 2) y (2N), stored in the fourth accumulator 13 (the array of which was formed in the previous cycle of operation of block 16, when the potential is the filter is connected to the second input of the adaptive filtering unit, the output of which through the third switch is connected to the third and fourth drives connected through the fourth switch to the digital-to-out output (low), through the fourth converter, while the controlled switch 14 is outputted to D / A converter 15, where the analog is restored The main inputs of the switches are connected to the output of the control unit. signal y (t), which is the output signal of the compensator 1. After the low potential (Fig. 2) is fed to the switches 4, 7, 11 and 14 from the output of block 16 in the next cycle of operation, the accumulation of successive arrays of N input samples (4JV + 1), x (), ..., x (5N) and L / filtered samples 0 (SLCH-1), “/ (SLCH-2), ..., y (4N) 0 occurs, respectively, in the second 6 and fourth 13 accumulators, and the reading of the next N input samples (SLCH-1), x (SSCH-2), .... (4LO for filtering and N filtered samples y (2N +), y (2N + 2) y (3N) for feeding to the DAC 15, respectively, occurs from the first 5 and third 12 accumulators of input and filtered signals. Thus, in the compensator 1 of the adaptive acoustic self-excitation suppression device, periodically (once per t0 s), coefficients are calculated for the adaptive filtering unit 9, according to analysis of a sample of 5 samples of the input signal x (t) and in accordance with the calculated coefficients it is filtered. thirty Invention Formula An adaptive acoustic self-excitation suppressor device comprising a distortion compensator connected in series and a frequency shift unit, characterized in that, in order to simplify the operation and increase the suppression depth reflected signals by eliminating regenerative and multiplicative distortions, the compensator contains an analog-to-digital converter, the output of which is a sub switch is the first switch, the outputs of which are connected to the first and second drives connected through the second switch to the first input of the adaptive filtering unit and the input of the correlator sample calculator function, whose output through the coefficient calculation unit through the coefficient calculation unit The filter is connected to the second input of the adaptive filtering unit, the output of which through the third switch is connected to the third and fourth drives connected via the fourth switch to the digital-to-analog converter, while the control inputs of the switches are connected to the output of the control unit.  2 h 1 tb P gg