RU2275693C2 - Diver's speech corrector - Google Patents

Abstract

FIELD: diver's equipment.

SUBSTANCE: diver's speech corrector with smoothly changing factor of frequency correction has microphone 1, low frequency amplifier 2, 17, balance modulator 3 onto which the voltage of high-frequency signal is applied from the first heterodyne 4, narrow-band filter 5 extracting one side band, amplifier-restrictor 6, frequency detector with low frequency filter (0-3-Hz), low frequency amplifier 8 having variable amplification factor, high frequency frequency-modulated generator 9, single-band loudness envelope detector 10, loudness envelope amplifier 11 with low frequency filter (0-35 Hz), high-frequency signal amplitude modulator 12, high frequency amplifier 13, signal amplitude detector 14 onto which the high frequency voltage is applied from the second heterodyne 15, frequency corrector 16, low frequency amplifier 17, output loudspeaker 18.

EFFECT: improved precision.

1 dwg

Description

The invention relates to diving equipment, and in particular to correctors (converters) of the speech spectrum of deep-sea divers. It is known that when breathing helio-oxygen mixtures, the diver's speech spectrum shifts toward higher frequencies and speech correction is necessary to ensure normal communication with the surface.

Known domestic voice converters of telephone exchanges VPS-1 and VPS-2 developed by OJSC "Long-distance Communications" - analogues (Analytical review of military-scientific information, issue No. 4, 2000, NTI Navy 78.25.25.37.41) and VTS-59m - prototype. A description of the prototype can be found in the book of N.A. Stoptsov et al. “Communication under water”, ed. "Shipbuilding", Leningrad, 1990, p. 177.

The device that corrects the frequency spectrum of a diver’s speech in the VTS-59m is based on a spectral-band method for analyzing and synthesizing a speech signal.

According to this method, the electric signal received from the diver’s microphone, after amplification by the input amplifier, enters the speech transducer to the correction amplifier for frequency compensation of spectrum distortions. The output of the correction amplifier is loaded onto a comb of band-pass filters of the analyzer, covering the adjacent frequency bands with the frequency range of the diver's initial speech spectrum of 500-7200 Hz. In order to obtain satisfactory intelligibility and natural sounding of the transformed speech, the indicated frequency range is divided by the analyzer filters into 14 bands. In each band, the average voltage value is determined by rectifying the voltage at the output of each filter by the detector and excluding from the rectified voltage all the higher components using low-pass filters 0-80 Hz. The average voltage values obtained in this way act on the modulators as control signals and are used in the synthesizer to convert the speech spectrum in each band.

The source of the carrier frequencies uses harmonic components of the fundamental tone, isolated from the spectrum of the original signal by bandpass filters of the carrier frequencies, also connected to the output of the input amplifier. The frequency bands of these filters are shifted an octave in the direction of low frequencies relative to the filter bands of the analyzer.

At the output of each modulator, a signal is generated with a wide spectrum of frequencies proportional to the magnitude of the control signal, from which a frequency band is allocated using the synthesizer filter, shifted by an octave toward low frequencies. The total synthesized signal is similar to the nature of the intensity of the original speech spectrum and has a range of 250-3600 Hz.

The disadvantages of the prototype include significant distortion of the speech spectrum, since the synthesized sound does not contain the fine signal structure inherent in live speech, because all its components falling into the same frequency band have the same values. The way out of this situation may be to increase the number of analyzer filters, which leads to a significant increase in the dimensions and cost of the equipment.

Another disadvantage is the fixed magnitude of the shift in the speech spectrum (exactly one octave down) regardless of the composition of the breathing mixtures and the depth of the diver. This also leads to a deterioration in speech intelligibility, since the initial spectrum of the speech signal shifts upward in frequency by different values depending on the composition of the mixture and the depth of immersion of the diver. In the ideal case, the coefficient of the frequency correction of the speech of the diver should be a variable, gradually varying in the range from 1 to 0.3.

A significant disadvantage of the prototype are also the significant dimensions and cost of the speech transducer.

The objective of the invention is the creation of a speech corrector diver with a smoothly changing coefficient of frequency correction, having significantly smaller dimensions and cost compared to existing ones.

The problem is solved by frequency modulation of the generator of the high-frequency signal of the frequency component of the speech spectrum, followed by the imposition of the volume envelope of the spectrum.

The drawing shows a block diagram of a speech corrector diver.

The speech corrector contains: microphone 1; low frequency amplifier 2; balanced modulator 3, to which the voltage of the high-frequency signal is supplied from the first local oscillator 4; narrow-band filter 5, emitting one side band; limit amplifier 6; frequency detector 7 with a low-pass signal filter (0-300 Hz); variable frequency amplifier with a variable gain of 8; frequency-modulated high-frequency generator 9; the detector of the volume envelope of the single-band signal 10; amplifier envelope envelope with a low-pass filter (0-35 Hz) 11; amplitude modulator of the high-frequency signal 12; high-frequency signal amplifier 13; an amplitude signal detector 14, to which a high-frequency voltage is supplied from the second local oscillator 15; frequency corrector 16; low frequency amplifier 17; output speaker 18.

The speech corrector works as follows.

The low-frequency signal from the microphone of the diver 1 is amplified by the amplifier 2 and fed to the balanced modulator 3. A high-frequency signal from the first local oscillator 4 is fed there. A two-band high-frequency signal with a suppressed carrier is generated at the output of the balanced modulator. At the output of filter 5 we get a single-band signal. Amplifier limiter 6 eliminates the loud envelope of the signal. The frequency detector 7 converts a frequency-varying signal into a low-frequency amplitude-modulated one. The low frequency amplifier 8 amplifies the signal, and the gain can vary in a given range. A low-frequency signal is used to frequency modulate another high-frequency generator 9. In this case, the frequency deviation is determined by the level of the low-frequency signal. The coefficient of frequency correction of speech is defined as the ratio of the width of the spectrum of the output signal to the original spectrum at the input of the corrector. For divers using helio-oxygen mixtures, the correction factor should be less than one. This means that the frequency deviation of the generator 9 should be less than the initial deviation at the output of the amplifier-limiter 6. By changing the gain of the amplifier 8, you can get any necessary frequency deviation. Thus, the spectrum of the input signal is multiplied by the correction factor.

Further, in the modulator 12, the loudness envelope of the initial speech spectrum selected by the detector 10 is superimposed on the newly received high-frequency signal, thereby restoring the fine structure of the signal. The signal is then amplified and detected as a normal single-band signal. The suppressed carrier is restored using the second local oscillator 15. The frequency of the local oscillator can vary within small limits (± 100 Hz), which allows you to shift the low-frequency spectrum of speech up or down in frequency, achieving the greatest intelligibility. The frequency corrector 16 allows you to change the level of the upper and lower frequencies of the speech spectrum. After amplification, the converted speech signal is supplied to the loudspeaker 18.

The use of the invention allows a fairly simple and cheap way to convert the distorted spectrum of a diver's speech into a speech spectrum familiar to hearing, while maintaining the fine structure of the signal.

It is possible to use the corrector for pop purposes, to create special sound effects. In this case, the correction factor may be greater than one.

Claims (1)

A diver’s speech corrector containing a microphone, input and output low-frequency amplifiers and a loudspeaker, characterized in that after the input amplifier there is a balanced modulator connected to the first local oscillator, and a narrow-band filter, the output of which is connected in one line with an amplifier-limiter, a frequency detector, a low-frequency amplifier with a variable gain, a frequency-modulated high-frequency generator and the first input of an amplitude modulator of a high-frequency signal, and on the other line One narrow-band filter is connected to the detector of the volume envelope of the signal, the amplifier of the volume envelope, and then to the second input of the amplitude modulator of the high-frequency signal, the output of which is connected to the amplifier of the high-frequency signal, and then to the amplitude detector of the signal, which is connected to the second local oscillator, and the output of the amplitude detector is connected with a frequency corrector and further with an output amplifier of a low frequency.