KR100203242B1 - Device for the frequency compensation of a magnetic recording/reproducing equipment - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio processing apparatus of a VCR (Video Cassette Recorder). When an image signal is recorded on a magnetic recording tape in a low speed mode such as SLP = EP of an audio modulation method (AM), a high frequency component is not recorded so that a predetermined frequency or more Compared to the conventional one, where a signal cannot be reproduced, a signal is converted to a predetermined high frequency into a low frequency, and provided with key control means for restoring it back to the original signal during reproduction, thereby providing an advantage of compensating sound quality during magnetic recording.

Description

Frequency compensator of magnetic recording and reproducing system

1 is a block diagram illustrating a recording system of a frequency compensating device of a magnetic recording and reproducing system according to an embodiment of the present invention.

2 is a block diagram illustrating a reproducing system of a frequency compensating device of a magnetic recording and reproducing system according to a preferred embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

10: key input unit 11, 21: equalization amplifier

13: control unit 15: head

25 line amplifier 30 conversion means

32: A / D converter 34: buffer

35: D / A converter SW1, SW2, SW3, SW4: switch

The present invention relates to an audio signal processing apparatus of a video cassette recorder (VCR). In particular, the present invention relates to recording by performing a band compression to change the frequency of an audio signal input to a recordable low frequency when recording at a specific speed. The present invention relates to a frequency compensation device of a magnetic recording and reproducing system which expands and reproduces a compressed low frequency wave at a high frequency during reproduction.

In general, the tape speed of a VCR can be classified into standard play (SP), long play (LP), and super long play (EP). When a video signal is recorded on the magnetic recording tape in a low speed mode such as SLP, high frequency components above a predetermined frequency are not recorded, so reproduction over a frequency of approximately 5 kHz is impossible. Conventionally, in order to solve this problem, the frequency compensation is possible to some extent by changing the characteristics of the EQ AMP (Equalizer Amplifier), but the frequency distortion occurs, the noise level is higher, and so on. There was a problem with this conversion.

Accordingly, an object of the present invention is to compress and record a high frequency audio signal that is actually applied in order to widen the frequency band of the reproducible voice signal according to the speed of the tape in order to solve the above problems, and to compress the low frequency compressed signal. The present invention provides a frequency compensation device of a magnetic recording and reproducing apparatus for restoring an original high frequency signal to reproduce an audio signal recorded at a high frequency.

A feature of the present invention for achieving the above object is in the audio signal processing apparatus of the magnetic recording system for recording a predetermined high frequency audio signal on the magnetic recording tape, recording the audio signal input according to the control signal of the controller at a reference speed It is connected to the transfer to the head directly when, when recording at a reference speed is less than the switching means connected to transfer the audio signal to the conversion means, outputs a control signal for switching the switching means in accordance with a recording speed selection signal applied from the outside, A control unit for adding a recording frequency conversion marker signal to a control track of the magnetic recording tape on which the audio signal is recorded when recording at a reference speed lower than the reference speed, and sampling the high frequency analog audio signal amplified by the switching means at a sampling frequency and Is converted to the sampling frequency By re-sampling to a lower frequency in the frequency conversion to an analog compensator of the magnetic recording system including a conversion means for converting a low-frequency audio signal having a broad range.

Another feature of the present invention for achieving the above object is an audio signal processing apparatus of a magnetic reproduction system for reading out and reproducing a signal recorded at a predetermined reference low frequency on a magnetic recording tape, and recording it on a control track of the magnetic recording tape. A control unit for outputting a switching switching signal to the switching means according to the presence or absence of the recorded frequency conversion marker signal, and if the recording frequency marking signal is not detected according to the switching switching signal of the controller, the read signal is output as it is, and the recording frequency marker When a signal is detected, the switching means connected to output the read low frequency audio signal to the converting means, and when the recording frequency marker signal is detected and the low frequency audio signal is applied from the switching means, band extension is restored to the original high frequency signal before recording. Magnetic regeneration system comprising a conversion means It is in the frequency compensation device of the system.

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

1 is a block diagram for explaining a recorder of a frequency compensating device of a magnetic recording and reproducing system as the apparatus of the present invention. The frequency compensating device includes a recording equalization amplifier 11 for receiving and amplifying a received audio signal. The first switch SW1 and the second switch SW2 are connected to the output terminal of the recording equalization amplifier 11. The first switch SW1 and the second switch SW2 operate opposite to each other. That is, when the first switch SW1 is turned on, the second switch SW2 is turned off. When the first switch SW1 is turned on, the second switch SW2 is turned off. The key input unit 10 outputs a frequency compensation mode selection signal to the control unit 13. Accordingly, the controller 13 applies a switching control signal to the first switch SW1 and the second switch SW2. When the first switch SW1 is turned on according to the switching control signal of the controller 13, the first switch SW1 transfers the output of the recording equalization amplifier 11 to the head 15. The conversion means 30 is connected to the second switch SW2, and when turned on according to the switching selection signal of the control unit 13, the output of the recording equalizing amplifier 11 is transmitted to the conversion means 30. . The converting means 30 samples the high frequency analog audio signal amplified by the second switch SW2 at a sampling frequency and converts it to digital, and resamples to a frequency lower than the sampling frequency to convert to analog to convert the low frequency audio into a wide range. Convert to a signal. The conversion means 30 includes an A / D converter 32 for sampling a high frequency audio signal at a sampling frequency and converting the digital signal into a digital form, a buffer 34 for storing the digitally converted audio signal, And a D / A converter 35 for resampling the digital audio signal stored in the buffer 34 to a frequency lower than the sampling frequency. The above-described conversion means 30 can be implemented by employing an integrated circuit (IC) incorporating an A / D converter 32, a buffer 34, and a D / A converter 35 called M65840FP.

In FIG. 1, the recording equalizing amplifier 11 receives and amplifies an audio signal carried in a received video signal and outputs the amplified signal to the first switch SW1 and the second switch SW2. The controller 13 outputs a switch control signal for turning on the first switch SW1 when the key signal for recording at the normal speed SP is received from the key input unit 10. Therefore, the audio signal amplified by the recording equalizing amplifier 11 is transmitted to the head 15 through the first switch SW1. The head 15 records the applied audio signal on the tape at a normal speed SP. On the other hand, when the control unit 13 receives a key signal for selecting the frequency compensation mode from the key input unit 10, the controller 13 outputs a switching control signal for turning on the second switch SW2. Then, the output of the recording equalizing amplifier 11 is applied to the converting means 30. The A / D converter 32 samples a high frequency analog audio signal input from the second switch SW2 at a sampling frequency and converts the signal into a digital form. At this time, the sampling frequency satisfies the sampling theorem of the theory that "when sampling and transmitting at a frequency more than twice the maximum frequency (fmax) of a signal, the receiving side can accurately reproduce the signal waveform and reproduce it as an original signal." As a frequency, it is also called a Nyquist frequency. In general, the higher the sampling frequency, the denser the sampling, the better the phase linearity and the better the audio signal can be reproduced over the entire band. The buffer 34 stores the audio signal digitally converted by the A / D converter 32. The D / A converter 35 converts the digital audio signal stored in the buffer 34 into an analog form by reversing the A / D process, that is, resampling. The D / A converter 35 resamples the frequency of the audio signal to a lower frequency than the sampling frequency at the time of A / D conversion in the A / D converter 32, thereby converting the frequency of the audio signal into a low frequency and outputting it to the head 15. The head 15 records the frequency-converted signal on the tape in accordance with the recording control signal of the control unit 13. The control unit 13 records a predetermined frequency conversion marker for recognizing the portion where the frequency-converted signal is recorded in an interval in the control section of the tape to be used during reproduction.

2 is a configuration diagram for explaining a reproducing system of a frequency compensator for reading out and reproducing a recorded signal as described above.

In Fig. 2, the head 15 reads out the signal recorded from the tape and outputs it to the reproduction equalizing amplifier 21 and the control unit 13. The control unit 13 determines whether the frequency conversion marker signal has been recorded in the control section of the tape. The control unit 13 turns on / off the switches SW3 and SW4 according to the frequency conversion marker signal. At this time, the third switch SW3 and the fourth switch SW4 operate opposite to each other. If there is no marker signal recorded in the control section of the tape, the controller 13 outputs a control signal for turning on the third switch SW3. Therefore, the output from the regenerative equalization amplifier 21 is output to the line amplifier 25 through the third switch SW3. The line amplifier 25 amplifies and outputs the applied reproduction signal to an appropriate level.

On the other hand, if it is determined that the frequency marking signal is recorded in the control section of the tape, the control unit 13 outputs a control signal for turning on the fourth switch SW4. At this time, the third switch SW3 is turned off. Therefore, the frequency-converted signal amplified from the regenerative equalization amplifier 21 is applied to the conversion means 30 through the fourth switch SW4. The converting means 30 operates in the opposite manner to the operation described with reference to FIG. 1, that is, the high frequency input signal is converted to low frequency. The A / D converter 32 receives an analog audio signal converted into a low frequency from the reproduction equalization amplifier 21 and samples it at a sampling frequency to convert it into a digital form. The buffer 34 stores the digitally converted audio signal. The D / A converter 35 converts the digital audio signal stored in the buffer 34 into a high frequency audio signal by resampling at a sampling frequency higher than the sampling frequency, and outputs the high frequency audio signal to the line amplifier 25. The line amplifier 25 amplifies and outputs the recorded actual high frequency signal to an appropriate size.

Accordingly, the present invention relates to an audio processing apparatus of a VCR (Video Cassette Recorder). When an image signal is recorded on a magnetic recording tape in a low speed mode such as SLP = EP of an audio modulation system (AM), high frequency components are not recorded. The audio signal of frequency has the advantage of compensating for the sound quality during magnetic recording by providing a conversion means for compressing and recording a high frequency audio signal into a low frequency signal, and restoring it back to the original signal when the audio signal is not reproduced. To provide.

Claims (4)

In an audio signal processing apparatus of a magnetic recording system for recording a predetermined high frequency audio signal on a magnetic recording tape, the audio signal inputted according to a control signal of a controller is connected so as to be transferred directly to a head when the audio signal is recorded at a reference speed, and is less than the reference speed. Switching means connected to transmit the audio signal to a conversion means when recording to Outputs a control signal for switching the switching means in accordance with a recording speed selection signal applied from the outside, and adds a recording frequency conversion marker signal to a control track of the magnetic recording tape on which the audio signal is recorded when recording at a reference speed below. A control unit; And conversion means for converting the high frequency analog audio signal amplified from the switching means into a digital sampled at a sampling frequency, and converting the digital audio signal into a low frequency audio signal having a wide range by resampling to a frequency lower than the sampling frequency and converting the analog signal. Frequency compensation device of a magnetic recording system comprising. 2. The apparatus of claim 1, wherein the converting means comprises: an A / D converter for sampling the analog audio signal at a sampling frequency and converting the analog audio signal into a digital form; A buffer for storing the digitally converted audio signal; And a D / A converter for resampling a low frequency audio signal by resampling the digital audio signal stored in the buffer to a sampling frequency lower than the sampling frequency. In the audio signal processing method of a magnetic reproducing system which reads out and reproduces a signal recorded on a magnetic recording tape with a predetermined reference low frequency, the switching means is switched according to the presence or absence of a recording frequency conversion marker signal recorded on the control track of the magnetic recording tape. A controller for outputting a switching switching signal; Switching means connected to output the read signal as it is if the recording frequency marker signal is not detected according to the switching switching signal of the controller, and outputting the read low frequency audio signal to the converting means when the recording frequency marker signal is detected; And converting means for band-extending and restoring the original high frequency signal before recording when the recording frequency marker signal is detected and the low frequency audio signal is applied from the switching means. 4. The apparatus of claim 3, wherein the converting means comprises: an A / D converter for sampling the analog audio signal at a sampling frequency and converting the analog audio signal into a digital form; A buffer for storing the digitally converted audio signal; And a D / A converter for resampling the digital audio signal stored in the buffer to a sampling frequency lower than the sampling frequency to convert a high frequency audio signal.