KR100231449B1 - Circuit for separating background music and voice from audio signal - Google Patents

Abstract

The present invention provides an audio and background music separation circuit of a high fidelity audio signal that separates an audio signal of a music program into a sound signal component and a background music signal component, and records and reproduces it on a video tape of hi fi. It is about.

A feature of the present invention is that an audio input of a first channel, which includes a music component and a voice component in common, is applied to a second mixer through a voice band pass filter circuit and a phase inversion circuit, whereby the audio signal of the second channel is applied. By canceling the included audio components, only the pure background music signal components are applied to the second input terminal of the hi-fi IC, and the audio input of the second channel including the music components and the voice components in common is a music band pass filter circuit. And a phase inversion circuit to be applied to the first mix, whereby a music component contained in the audio signal of the first channel is canceled so that only pure audio signal components are applied to the first input terminal of the hi-fi IC. Audio output and music output output from the first and second output terminals of Hi-Fi IC are respectively It is configured to be applied to a portion fidelity audio signal recording circuit.

Such the present invention has an effect that can be used as a background music for language learning or song practice using the existing music program.

Description

Voice and background music separation circuit of audio signal

The present invention provides an audio and background music separation circuit of a high fidelity audio signal for separating audio signals of a music program into audio signal components and background music signal components and recording and reproducing them on a video tape of hi fi. It is about.

The audio reproduction signal processing system applied in the VSI having the hi-fi function is a pair of audio rotating heads installed on a rotating drum, and a preamplifier that amplifies the signals picked up from the audio heads through a recording / playback switching switch and performs ultra-high amplification. And a channel switch for outputting the output of the preamplifier to each band pass filter side according to the control output of the head switch pulse generator, a signal demodulator, a dropout detector, and an output of the head switch pulse generator. The sample holder to be executed, the noise attenuator, and the output amplifier are included.

The audio head is installed together with the video heads on the rotating drum to obtain a high tape speed, unlike the fixed head type standard VSI in high fidelity.

The audio rotating head method solves the problem that the fixed head method has a low frequency characteristic or wow flutter, and the high sound quality cannot be obtained due to the decrease in tape traveling speed due to prolonged time.

Tape speed in VSI's standard audio mode is about 3.3 cm per second, and in triple speed mode its speed is 1.1 cm.

This tape running speed is only 1/2 to 1/4 of the audio cassette tape recorder's speed of 4.8 cm per second, so it is difficult to expect high quality audio playback.

In order to improve the low tape running speed of the audio head and to obtain high quality audio, it is required to increase the speed of tape life for the audio head, which focuses on the rotating head used for recording and reproducing the video signal. Hi-Fi video is used for recording and playback.

The relative speed between the Hi-Fi audio rotating head and the tape is about 6 meters per second, which is 200 to 300 times faster than the fixed head method for monaural audio playback. In addition, the hi-fi method records the audio signal in the form of FM along the rotating head. In order to record the video signal on the tape with high density, the audio signal and the video signal must be multiplexed on the tape in a special way.

Therefore, in Hi-Fi and voice multiple VSI, audio and video signals are recorded in the thickness direction of the tape.

At this time, the audio signal is first recorded in the deep portion of the tape by using two dedicated rotating audio heads, and the audio signal is overlaid on the tape layer portion of the portion where the audio signal is recorded using the existing rotating video head.

Here, the carrier of the audio signal is recorded in the deep magnetic layer of the tape because the frequency is set lower than that of the luminance signal and the audio head gap is designed to be wider than the video head gap.

FIG. 1 shows the configuration of an audio signal processing circuit in high fidelity.

As referred to herein, the television broadcast signal received through the antenna is connected to the tuner stage 10 after the desired channel is tuned and converted into an intermediate frequency signal to be transmitted to the image intermediate frequency amplifier stage 11.

The image intermediate frequency signal output from the image intermediate frequency amplifier stage 11 is configured to be applied as an image signal to the image recording stage 14 through the image detector 12 and the image signal processing stage 13.

In addition, the video intermediate frequency signal output from the video intermediate frequency amplifier stage 11 is applied to the audio intermediate frequency amplifier stage 15 so that the audio intermediate frequency signal is picked up and amplified and output.

The voice intermediate frequency signal output from the voice intermediate frequency amplifier stage 15 includes a first signal consisting of a first BPF 16, a signal amplifier stage 17, a first FM detector 18, and a first equalization stage 19. A pass is provided to be provided to the first input of the hi-fi IC 24.

In addition, the voice intermediate frequency signal output from the voice intermediate frequency amplifier stage 15 includes a second BPF 20, a signal amplifier stage 21, a second FM detector 22, and a second equalization stage 23. It is connected to be provided to the second input of the hi-fi IC 24 via the signal path.

The two-channel audio signal output from the hi-fi IC 24 is recorded on the videotape as a voice signal of the corresponding program via the audio recording stage 29. Here, the frequency characteristic of the first BPF 16 is set to 4.5 MHz, and the frequency characteristic of the second BPF 20 is designed to be 4.724 MHz.

Meanwhile, the voice signal filtered and output from the second BPF 20 is connected to the pilot detection terminal 26 via the third BPF 25 having a frequency characteristic of 55.1 MHz. The pilot signal output signal from the pilot detection stage 26 controls the hi-fi IC 24 and the tuner stage 10, and the voice equalization levels of the first and second equalization stages 19 and 23. It is configured to connect to be provided to the microcomputer 27 to be set automatically. The microcomputer 28 has a timer 28.

Referring to the operation of the VSI voice processing circuit configured as described above are as follows.

When a television RF broadcast signal is input to a tuner stage 10 of a television or a television through an antenna, the tuner stage 10 receives an image intermediate frequency from a broadcast signal of a channel tuned according to the electronic tuning control of the microcomputer 27. The PIF) signal is taken out and output to the image intermediate frequency amplifier stage 11.

The image signal passing through the image intermediate frequency amplifier stage 11 is applied as an image signal to the image recording stage 14 through the image signal processing stage 13 after being detected by the image detecting stage 12, and then on the video tape. Records will be made.

Meanwhile, the PIF output of the image intermediate frequency amplifier 11 is input to the audio intermediate frequency amplifier 15. This speech intermediate frequency amplifier stage 15 picks up the SIF signal from the speech intermediate frequency (PIF) signal and amplifies and outputs it.

The audio intermediate frequency signal output from the audio intermediate frequency amplifier stage 15 includes a first signal path including a first BPF 16, a signal amplifier stage 17, a first FM detector 18, and a first equalization stage 19. Is transmitted to the first input terminal of the hi-fi IC 24.

In addition, the speech intermediate frequency signal output from the speech intermediate frequency amplifier stage 15 includes a second BPF 20, a signal amplifier stage 21, a second FM detector 22, and a first equalization stage 23. The signal is transmitted to the first input terminal of the hi-fi IC 24 via two signal paths.

The hi-fi IC 24 inputs a voice signal input through the first and second signal paths through a respective R / L channel to a hi-fi stereo mode, a voice multiple mode, or a monaural mode voice. The output will be in mode.

The microcomputer 27 uses a pilot signal as a source for switching the voice signal hi-fi IC 24. That is, if the pilot signal frequency is 150 Hz, it is determined as stereo broadcasting, and if it is 276 Hz, it is determined as voice multiple broadcasting to control the hi-fi IC.

The pilot signal is detected by the pilot detection stage 26, and the voice filtering signal of the second BPF 20 passing through the third BPF 25 having a frequency characteristic of 55.1 KHz is applied to the pilot detection stage 26. do.

On the other hand, when the pilot detection stage 26 detects the pilot signal from the voice intermediate frequency signal passing through the third BPF 25 and transmits it to the microcomputer 27, the microcomputer 27 determines whether the pilot signal is present. In addition, when a pilot signal is being input, the frequency of the pilot signal is determined to be 150 Hz or 276 Hz. Therefore, as described above, the voice hi-fi IC is controlled to be switched to stereo mode, voice multiple mode, or monaural mode. will be.

The voice mode determination control signal output from the microcomputer 27 is provided to the first and second equalization stages 19 and 23 of the first and second signal paths. In this case, the first and second equalization stages 19 and 23 have at least three voice equalization levels under the control of the microcomputer.

On the other hand, the microcomputer 27 determines whether the pilot signal is present through the pilot detection stage 26 from the voice intermediate frequency signal of the tuner stage.

In this case, if the pilot signal is not detected, the microcomputer 27 determines the current broadcast mode as the voice monaural mode, and otherwise determines the stereo and voice multiplex (ST / BL) mode. In addition, when the pilot signal is detected in the broadcast mode determination step, the microcomputer 27 determines the ST / BL mode and determines whether it is the stereo broadcast mode or the voice multiple mode from the magnitude of the pilot signal frequency.

That is, when the pilot frequency is detected at 150 Hz, it is determined as the stereo broadcast reception mode and is detected as 276 Hz.

When the current broadcast mode is determined as described above, the microcomputer 27 is used for recording program related equipment and control circuits such as the tape deck unit, the video recording stage 14, and the audio recording stage 29 according to the reservation recording conditions for each broadcast mode. Selective on / off control of operating power enables hi-fi recording.

The high-fidelity audio signal processing system that operates in this way only separates the audio signal into left and right channels to add the liveliness and realism of the music program, and pure music segments and pure voice components are not separated. Could not be used as an accompaniment for singing practice.

An object of the present invention is to separate the audio signal of a music program into a voice signal component and a background music signal component, and to separate the voice and background music of the audio signal for hi-fi To provide a circuit.

The present invention provides a voice filter circuit for filtering only a voice signal of an audio signal L of a first channel having a music component and a voice component, a phase reversal circuit for phase reversing a voice signal filtered by the voice filter circuit; Mixing the signal component generated by the phase inversion circuit and the audio signal R of the second channel cancels out the voice component and sends only the music component to the second input terminal of the Hi-Fi IC. A voice trap circuit for filtering only a music signal among audio signals R of a second channel having a phase, a phase inverting circuit for phase inverting the voice signal filtered by the voice trap circuit, and a signal component generated by the phase inverting circuit And a first mixer for mixing the audio signal L of the first channel to cancel the music component and sending only the audio component to the first input terminal of the hi-fi IC 24. An audio output and music output from each output terminal is characterized in that V is applied to the audio output terminal and the V-sialic interior of hi-fi audio signal recording circuit provided in the rear side of the sialic.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

1 is a circuit diagram of a general audio signal processing system of VSI.

2 is a circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

24: hi-fi IC 29: voice recorder

31: voice trap circuit 32: phase inversion circuit

33: first mixer 34: voice filter circuit

35: phase inversion circuit 36: second mixer

2 shows a circuit configuration of the present invention.

As referred to herein, the L-channel audio signal output from the existing first equalizing stage 19, that is, the signal having the voice signal component A and the background music signal component B, is the first mixer 33. And a signal having a voice signal component (A) and a background music signal component (B) of the R channel outputted from the second equalization stage 23, respectively. And 36 to be applied to the sound trap circuit 31.

The voice filter circuit 34 is made of a band pass filter having a frequency band of 1-3KHZ, and the voice signal component A passed through the voice filter circuit 34 is connected to the phase inversion circuit 35. The audio signal component, ie, the -A signal component, which is phase-inverted and output from the phase inversion circuit 35, is applied to the second mixer 36.

In addition, the voice trap circuit 31 is made of a band rejection filter having a frequency band of 1-3KHZ, except that the signal component except for the voice signal component (A), that is, the background music signal component (B) has a phase It is connected to the inversion circuit 32 to be applied. A background music signal component, ie, a -B signal component, output from the phase inversion in the phase inversion circuit 32 is connected to the first mixer 33.

The audio signal components and the music signal components mixed and output from the first and second mixers 33 and 36 are input to the hi-fi IC 24 for processing, and the output of the hi-fi IC 24 is connected to Connect to the hi-fi audio output terminal of and to the audio signal recording circuit.

Referring to the operation of the present invention configured as described above is as follows.

First, a part of the L-channel hi-fi audio signal output from the first equalization stage 19 is applied to the first mixer 33 as it is, and the other part is applied to the voice filter circuit 34.

Since the voice filter circuit 34 is made of a filter circuit having a band pass filtering characteristic of 1-3KHZ, only the voice signal component A appears at the output terminal of the voice filter circuit.

Since the voice signal is inverted by 180 ° while passing through the phase inversion circuit 35, the voice signal component at this time becomes -B and is applied to the first mixer 33.

Therefore, in the first mixer, only the simple voice signal component A is generated by the formula A + B (-B) = A and transmitted to the first input terminal of the hi-fi IC 24. In the second mixer, A + B The simple background music signal component B is generated by the formula (-A) = B and transmitted to the second input terminal side of the hi-fi IC 24.

The music audio signal separated and input to each of the independent signal components on the hi-fi IC side is signal-processed in the hi-fi IC to be transmitted to the audio recording circuit or hi-fi audio output terminal of VSI.

Therefore, it is very useful for language learning or singing practice because audio signal components can be listened or recorded separately by voice and music components according to the needs of hi-fi V'sial audio listeners.

As described above, the present invention can be completely recorded or outputted as a pure voice component and a pure background music component using a conventional Hi-Fi VSI, and thus, as a background music for language learning or song practice using the same. The effect is very useful.

Claims (1)

A phase inversion circuit for phase inverting the voice signal filtered by the voice filter circuit 34 and the voice filter circuit 34 for filtering only the voice signal of the audio signal L of the first channel having a music component and a voice component ( 35), the signal component generated by the phase inversion circuit 35 and the audio signal R of the second channel are mixed to cancel the audio component and only the music component is sent to the second input terminal of the hi-fi IC 24. The second mixer 36, the voice trap arc 31 for filtering only the music signal of the audio signal R of the second channel having the music component and the voice component, and the voice filtered by the voice trap circuit 31. A phase inversion circuit 32 for phase shifting a signal and a signal component generated by the phase inversion circuit 32 and an audio signal L of a first channel are mixed to cancel a music component and only a voice component is a hi-fi IC. A first mixer 33 which is sent to the first input terminal of 24; The audio output and the music output respectively outputted from the output terminal of the hi-fi IC 24 are applied to the audio output terminal provided at the rear side of the V-ial and the hi-fi audio signal recording circuit inside the V-sial. Voice and background music separation circuit.