SU1543454A1 - Device for extending dynamic range of signals in record-reproduction channel - Google Patents

Abstract

The invention relates to instrument making and allows improving the sound quality of cinema records. The control signal is formed as a circuit consisting of a single-sided modulator 2, amplitude limiter 3, amplitude detector 4. Then it is recorded as a frequency-modulated signal on the carrier 9 on the same track as the main signal, and the frequency band of the control signal directly above the frequency band of the main signal. Further, the main and control signals are multiplied in the reproduction channel by multiplier 13, resulting in pauses, as well as for signals that do not exceed the threshold level, decreases the level of noise and interference, which leads to the expansion of the dynamic range of signals in the recording-reproduction channel. 1 il.

Description

The invention relates to instrument engineering and can be used, when transmitting signals, advantageously, but when recording and reproducing signals.

The purpose of the invention is to improve the sound quality of cinema records.

The drawing shows a block diagram of the device.

The device contains in the recording channel the main signal path including the recording amplifier 1, the control signal path consisting of the single-band modulator 2 connected in series, the amplitude limiter 3, the amplitude-detector 4, the controlled oscillator 5, the first band-pass filter 6, and the common tract,

the included adder 7, one of the inputs of which is connected to the output of the recording amplifier 1, and the second to the output of the bandpass filter 6, a recording converter 8 which is connected to the common path of the playback channel including the serially connected playback converter 10 and amplifier 11 via the information carrier 9 playback, the output of which is connected to the main signal path including the first low-pass filter 12 and multiplier 13 connected in series, and the control signal path including the follow no connected the second band-pass filter 14, frequency detector 15 and second filter 16 low chassd

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one whose output is connected to one of the inputs of the multiplier 13, the second input of which is connected to the output of the filter 12, and the output of the multiplier 13 Is the output of the device.

The device works as follows.

The audio signal in the main signal path through the recording amplifier 1, which limits its frequency dia- meter (1} azon to avoid non-linear distortions, is fed to the first input of the adder 7. In the control signal path - j} a sound signal is transported i | o the frequency upward by a single sideband modulator 2, limited by amplitude-limiter 3, is detected by the Amplitude detector 4, the output of which is the control signal.

The control signal is fed to the control input of the controlled oscillator 5, which generates a frequency-modulated oscillation in a given frequency range. (For photographic sound recording, tbi are used from 10 to 12 kHz. With magnetic sound recording, the frequency deviation should be increased to increase noise immunity and the frequency band should be 20-25 kHz).

The first band-pass filter 6 limits the width of the spectrum to the frequency-modulated (shaken oscillation, which then goes to the second input of the adder 7, where it is added to a sound signal.

The electrical output signal of the sum-Mator 7 is converted by dp recording by the writing transducer 8, for which, depending on the type of information carrier, a light modulator, a magnetic recording head, etc. can be used.

The electrical nature of the signal is restored at the output of the playback converter 10. The signal is then amplified by the reproduction amplifier 11. The filter 12 extracts from the sum signal a sound main signal, which is fed to the first input of the multiplier 13.

The second band-pass filter 14 extracts the frequency-modulated oscillation, which is demodulated by the detector 15 with a 16 low-pass filter. The output restores the control signal in its original form,

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those. in the form of a unipolar voltage (or current). It enters the second input of the multiplier 13, where it is multiplied with the main signal. The resulting playback signal is thus:

1) in the pauses - the product of noise and interference of the transmission channel by zero of the control signal, as a result, at the output of the multiplier, only the noise of the multiplier can be observed;

2) for small signals not exceeding the threshold level, the product of a noisy sound signal and a signal proportional to the Hilbert envelope, as a result, the noise level at the output decreases, the dynamic range of the signal expands according to a square law, i.e. the instantaneous amplitude of the sound signal is squared;

3) for signals whose magnitude is higher than the threshold level, the product of the sound signal, which already masks the noise and interference of the channel quite well, by the constant value of the control signal, as a result of which the dynamic range of the sound signals is not converted above the threshold.

Claims (1)

Invention Formula A device for expanding the dynamic range of recording-reproduction channel signals comprising (input bus, recording amplifier, modulator, recording converter coupled via a storage medium with a playback converter connected by an output to the input of a playback amplifier, demodulator, output bus, different that, in order to improve the sound quality of cinema phonograms, sequentially connected amplitude limiter, amplitude detector, controlled oscillator, first bandpass A filter and an adder connected by an output to the input of a write converter and connected by another input through a recording amplifier with an input bus and an input of a modulator made in the form of a single-sideband modulated signal generator, the demodulator made in the form of serially connected first low-pass filter and multiplies connected in series the second low-pass filter of the low-pass filter, the output of which is connected to another input of the multiplier, the output of which is connected to the lower frequencies and the second band-pass The filter is connected to the output of the playback amplifier. VHOZ