KR0176241B1 - Apparatus for selectively recording and/or reproducing a video signal with a pcm audio signal or with an fm audio signal - Google Patents

Abstract

The video tape recording / reproducing apparatus or VTR includes a video head, a PCM audio head, and an FM audio head, demodulation circuits corresponding to these videos, PCM, and FM heads, switching circuits, signal detection circuits, and system control circuits, respectively. It includes a playback system comprising a. The video head, the PCM audio head, and the FM audio head read the video signal, the PCM audio signal, and the FM audio signal from the magnetic tape, and supply these signals to corresponding demodulation circuits and signal detection circuits. The signal detection circuit detects which of the video, PCM, and FM signals is recorded on the magnetic tape, and a switching signal for selectively connecting the signal output line and the FM and PCM audio demodulation circuit in response to the signal from the signal detection circuit. A signal indicating that the above signal is recorded is provided to the system control circuit for controlling the signal. Thus, the video signal and the PCM audio signal, or the video signal and the FM audio signal are output and reproduced. The VTR also includes a recording system. This recording system records video signals, PCM audio signals, and FM audio signals on respective magnetic layers of the magnetic tape. Each magnetic layer has a different depth to the surface of the magnetic tape in accordance with a predetermined recording current relationship used to record video, FM audio, and PCM audio signals, thereby improving the S / N ratio of each signal during playback. Give it.

Description

Information signal recorder

1 is a block diagram schematically showing a video signal recording and reproducing system that can be incorporated into an apparatus for recording and reproducing information signals according to an embodiment of the present invention.

2 is a block diagram schematically showing a PCM audio signal recording system using O-QDPSK modulation.

3 is a graph showing the band pass characteristics of the band pass filter used in the system of FIG.

4 is a diagram showing the frequency spectrum of an audio signal and a video signal recorded on a magnetic tape.

5 is a block diagram schematically showing an FM audio signal reproducing system and a PCM audio signal reproducing system built in an apparatus for recording and reproducing an information signal according to an embodiment of the present invention.

FIG. 6 is a flowchart showing a program or sequence of logic steps for controlling the FM and PCM audio signal reproduction system shown in FIG.

Fig. 7 is a block diagram schematically showing an FM audio signal recording and reproducing system that can be incorporated in an apparatus for recording and reproducing information signals according to the present invention.

8 is a block diagram schematically illustrating a signal recording system according to the present invention for selectively recording a video signal together with a PCM audio signal and / or an FM audio signal.

FIG. 9 is a graph showing the relationship between recording currents used to record video signals, PCM audio signals, and FM audio signals on a magnetic tape by the system of FIG.

FIG. 10 is a cross sectional view schematically showing a magnetic tape in which video signals, PCM audio signals and FM audio signals have been recorded by the system shown in FIG.

* Explanation of symbols for main parts of the drawings

150: video playback unit 200: video recording unit

220: FM modulator 230: frequency converter

240: mixer 250: video head unit

280, 284: regenerative amplifier

[Field of Invention]

The present invention relates to an apparatus for recording and reproducing an information signal, and more particularly to such an apparatus for identifying and appropriately reproducing differently modulated information signals recorded on a recording medium.

[Description of the Prior Art]

A color video signal which is separated into a low frequency conversion color signal and a frequency modulated gray signal and recorded on a magnetic tape or reproduced from a magnetic tape, and a color video signal which is frequency-modulated and recorded on a magnetic tape or reproduced from a magnetic tape, and A video tape recorder (VTR) for recording and reproducing audio signals has been proposed. In such a VTR, for example, the left channel signal and the right channel signal included in the stereo audio signal frequency modulate two carriers having different frequencies so that the left audio frequency modulated signal (L-AFM signal) and the right audio signal are modulated. Provide a frequency modulated signal (R-AFM signal). The frequency bands of these L-AFM and R-AFM signals are located between the frequency conversion color signal frequency band and the frequency modulated luminance signal frequency band. For example, as shown in FIG. 4, the carrier frequencies of the L-AFM and R-AFM signals are 0.3 MHz and 1.7 MHz, respectively.

As an improvement in sound quality, another type of VTR that converts audio signals into pulse code modulation (PCM) digital data, recorded on magnetic tape, and reproduced before audio / analog conversion of the digital audio signals to analog audio signals is widely used. Known. For this type of VTR, PCM digital data is modulated according to quadrature phase shift keying (QPSK) to obtain a QSPK modulated signal. As shown in Fig. 4, the frequency band of this QPSK modulated signal is also between the frequency converted color signal frequency band and the frequency modulated luminance signal frequency band. In this case, the center frequency of the QPSK modulated signal is 2 MHz. These audio frequency modulated signals (AFM) or QPSK modulated audio signals, including left and right AFM signals, are commonly used with the video signal by means of a rotating magnetic head separate from the rotating magnetic head used for recording the video signal. Recorded in the track area of the magnetic tape. The video signal is recorded on the surface layer of the magnetic tape, and the QPSK modulated signal or AFM signal is recorded in the deep portion of the magnetic tape.

In order to reproduce these signals recorded at different levels with magnetic coating on the magnetic tape, rotation heads for video signals and rotation heads for independent audio signals are provided to reproduce video signals and AFM or QPSK modulated signals, respectively. The reproduced video signal is supplied to the video signal reproduction system provided in the VTR, and the reproduced AFM or QPSK modulated signal is supplied to the audio signal reproduction system.

However, the conventional VTR including the AFM signal reproducing system and the conventional VTR including the QPSK modulated signal reproducing system are independent of each other. Therefore, an information signal including an AFM signal and a QPSK modulated signal cannot be reproduced by one existing VTR. Moreover, the user cannot easily distinguish between a tape on which an AFM signal is recorded and a magnetic tape on which a QPSK modulated signal is recorded. This causes a great inconvenience in determining the type of VTR to be used for reproducing a magnetic tape on which a video signal and an AFM or QPSK modulated signal are recorded.

[Object and Summary of the Invention]

Accordingly, an object of the present invention is to provide an apparatus for recording and reproducing, on a magnetic tape, an information signal including first and / or second signals having different frequencies, such as, for example, an FM modulated signal and / or a PCM signal. It is.

More specifically, an object of the present invention is to provide an apparatus for recording and reproducing the above information signal, detecting the type of the recorded signal and automatically selecting a reproducing circuit suitable for the same.

According to one aspect of the present invention, there is provided a reproduction means for reproducing an information signal recorded on a recording medium and including at least one of first and second signals having different first and second formats, and in the information signal. First detecting means for detecting the first signal and providing a first detection signal indicative of the presence of the first signal, and detecting the second signal in the information signal and indicating the presence of the second signal. Second detection means for providing a detection signal, signal output means, switching means for selectively supplying the first signal and the second signal from the reproducing means to the signal output means, and through the signal output means. An apparatus comprising control means for controlling said switching means in response to said first and second detection signals to selectively output said first signal and said second signal; It is.

According to another feature of the invention, recording means for recording an information signal including first, second, and third signals having different first, second, and third frequencies into a recording medium, and the recording means; Reproducing means for reproducing the information signal from a medium, first detecting means for detecting a first signal in the information signal and providing a first detection signal indicative of the presence of the first signal, and the second in the telegram signal Second detection means for detecting a signal and providing a second detection signal indicative of the presence of the second signal, signal output means, and transmitting the first signal and the second signal from the reproducing means to the signal output means. Switching means for selectively supplying said switching means in response to said first and second detection signals to selectively output said first, third signals, and said second and third signals through said signal output means; A recording information signal, which includes control means for controlling the playback apparatus is provided.

According to another feature of the invention, there is provided a signal source means for providing a first information signal, a second information signal, a third information signal, and a first write current of a predetermined value in a relatively deep layer in a magnetic coating on a magnetic tape. A first rotating magnetic head means for recording the first information signal and a second rotating magnetic head means for recording the second information with a second writing current in a second layer of the magnetic coating portion, the second recording current being The second rotating magnetic head means for causing the second layer to be in a magnetic coating part at a depth shallower than the depth of the first layer because the magnitude is smaller than the magnitude of the second write current; A third rotary magnetic head means for recording with a third write current on a third layer of the magnetic coating, wherein the third write current is smaller than the second write current so that the third layer is a magnetic material of the magnetic tape. Coating part The video tape recorder, which includes the third rotary magnetic head means to be in the surface portion.

According to another feature of the invention, a separation circuit for separating the input PCM information signal into a first data stream and a second data stream, a first balance modulator for receiving the first data stream, and the second data stream A second balanced modulator for receiving a second carrier and supplying means for supplying first and second carriers to the first and second balanced modulators, wherein the phase of the second carrier is shifted by 90 ° with respect to the first carrier. A band pass for receiving a carrier supply means, an adder for adding the output signal from the first balanced modulator, and an output signal from the second balanced modulator, and a bandpass for receiving the added signal output from the adder with a predetermined passband A fourth order phase shift keying modulation circuit including a filter is provided.

These and other objects, advantages, and features of the present invention will become apparent from the following detailed description of the preferred embodiments described with reference to the accompanying drawings. In the accompanying drawings, corresponding elements are represented by the same reference numerals in the various drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in detail, first, in FIG. 1, it can be seen that the video signal recording and reproducing system for a VTR according to the present invention generally includes a video reproducing unit 150 and a video recording 200. The recorder 200 is shown as including a Y / C separator 210, an FM modulator 220, a frequency converter 230, and an adder (or mixer) 240. The composite color video signal Sv is supplied from the input terminal to the Y / C separator 210 to be separated into the luminance component Y and the color component C. The luminance signal component Y is supplied to the FM modulator 220, where the relatively high frequency component is removed before being frequency modulated with the FM component having the frequency band indicated by Y in FIG. The color component C is supplied to the frequency converter 220, dropped to a relatively low frequency indicated by C in FIG. 4, and is frequency converted.

The frequency modulated luminance component Y and the frequency converted color component C are superimposed by supplying a positive component to the mixer 240. The mixed components are recorded in the oblique tracks of the magnetic tape 100 through the video head unit 250, each track containing a field of video signal.

In general, the magnetic heads 255 and 260 serving as the video head unit 250, the first channel CH-1 and the second channel CH-2, the recording / reproducing switching circuits 270 and 275, Regeneration amplifiers 280 and 284, write amplifiers 282 and 286 and switching switching circuits 290 and 295 are provided. Rotating magnetic heads 255 and 260 are disposed at positions opposite to each other on the periphery of the rotating head drum (not shown). Each recording / reproducing switching circuit 270, 275 is provided between the regeneration contact PB connected to the reproducing amplifier 280 or 284 and the recording contact REC connected to the recording amplifier 282 or 285, that is, A switching operation is performed in response to the signal output from the system controller 110 between the position indicated by the dotted line and the solid line in FIG. In accordance with the switching operation, each of the rotating magnetic heads 255 and 260 alternatively performs a reproduction or recording operation of a signal on the magnetic tape 100. The switching switching circuits 290 and 295 are connected to the rotating magnetic head 260 through the switching circuit 275 and the respective contact portions CH-1 connected to the rotating magnetic head 255 through the switching circuit 270. The switching operation between each contact portion CH-2 is performed. In other words, the switching circuits 290 and 295, in response to a signal from the system controller 110, switch between a position indicated by a dotted line in FIG. 1 and a position indicated by a solid line every half turn of the rotating magnetic head. Is done. Thus, during the recording operation, the magnetic head 255 (optionally) is alternately arranged such that a signal formed by mixing the luminance and color components in the mixer 240 is recorded on the magnetic tape 100 in accordance with the switching operation of the switching switching circuit 295. 260 is supplied.

The video signal reproducing unit 150 extracts a frequency modulated luminance component from the reproduced video signal and demodulates the demodulated channel to restore the component to its original frequency range, and extracts a frequency converted color component from the reproduced video signal. A color channel and an adder (or mixer) 80 for frequency reconverting this component back to the original frequency range are included. The luminance channel includes a band pass filter 155, a limiter 165 and an FM demodulator 175. The color channel includes a low pass filter 160 and a frequency converter 170.

During the reproduction operation, the composite video signal including the luminance component Y and the color component C is reproduced by the rotating magnetic heads 255 and 260 from the magnetic tape 100. The synthesized signal is transmitted to the band pass filter 155 and the low pass filter 160 through the switching circuits 270 and 275, the regeneration amplifiers 280 and 284, and the switching circuit 290. The band pass filter 155 separates the luminance component Y from the reproduced synthesized signal and supplies it to the FM demodulator 175 through the limiter 165. The FM demodulator demodulates the frequency modulated signal to recover the original luminance component.

On the other hand, low pass filter 160 separates the frequency converted color components from the reproduced composite video signal and supplies them to frequency converter 170. The frequency converter 170 is applied to the adder 180 after modulating the separated color components into the original frequency range. The adder combines the demodulated luminance component from FM demodulator 175 with the modulated color component from frequency converter 170 to provide a composite output video signal.

Referring now to FIG. 2, a PCM audio signal recording system 300 that conforms to offset-quadri differential phase shift keying (O-QDPSK) includes an A / D converter 310, an error correction encoder 315, The memory circuit 320 for the error correction encoder 315, the serial-to-parallel converter 325, the delay circuit 330, the difference code converters 335 and 340, the balance modulators 345 and 350, and the phase shift circuit 352. ), An oscillator 354, an adder circuit 355, a band pass filter 360, and a PCM head unit 370. The PCM head unit 370 performs the PCM audio signal recording and reproducing operation, and its configuration and operation are similar to those described with respect to the video head unit 250, so that further description of the PCM head unit 370 will be omitted. .

When the audio signal Sa is supplied to the A / D converter 310, it is converted into a PCM audio signal and supplied to the error correction encoder 315. The encoder 315 adds an error correction code to the PCM audio signal. The corrected PCM audio signal is then input to the serial-to-parallel converter 325 as data stream pairs ai and bi. This data stream pair is divided into an odd bit data stream ai and an even bit data stream bi. The stream ai is supplied to the delay circuit 330 to be delayed or offset by 0.5T (T is the signal generation period). The offset signal is supplied from the delay circuit 330 to the difference code converter 335 to be converted into the difference data stream ai ', and the data stream bi is supplied to the difference code converter 340 to supply the difference data stream bi. Is converted to '). This conversion is such that if there is a transition from one bit to the next in such serial data, for example if the bit changes from 1 to 0 or from 0 to 1, the corresponding bit of the difference data is assigned a value of 1. It is. If there is no bit change in the serial data, the corresponding bit of the difference data is assigned a value of zero. U.S. Patent No. 4,804,925, entitled DPSK EXCLUSIVE-OR DEMODULATOR, issued a patent to Iwase et al. And assigned to Fuji Photo Film Co., Ltd., describes such conversions, the contents of which are incorporated by reference. Included herein.

The difference data streams ai 'and bi' are fed to balanced modulators 345 and 350, respectively. Oscillator 354 supplies a cosωct signal to balance modulator 345 and phase shift circuit 352. Phase shift circuit 352 provides a sinωct signal by shifting the phase of the cosωct signal by [pi] / 2. The difference data stream ai 'is modulated with a cos (omegact + ai'pi) signal, and the difference data stream bi' is modulated with a sin (omegact + bi'pi) signal. These cos (ωct + ai'π) and sin (ωct + bi'π) signals are input to the addition circuit 355 to provide a 0-QDPSK modulated signal Sq represented by the following formula.

Here, the data streams ai ', bi' correspond to four types of data (0, 0), (1, 0), (1, 1), and (0, 1). Substituting these data into the tan ⁻¹ (cos bi'π / cos ai'π) term in the formula (1), the term is expressed as follows.

When the corresponding bits in the data streams ai 'and bi' are 0 and 0, respectively, the value of the term is π / 4, and when the corresponding bits in the data streams ai 'and bi' are 1 and 0, When the value of the term is 3π / 4 and the corresponding bits in the data streams ai 'and bi' are 1 and 1, the value of the term is 5π / 4 and the corresponding bits in the data streams ai 'and bi'. Is 0 and 1, the value of the term is 7π / 4. Thus, the value of equation (1) represents one of four points that are shifted from each other by [pi] / 2 according to the value of the corresponding bit in the data streams ai 'and bi'.

In a conventional PCM audio signal recording system, two low pass filters are placed between the serial-to-parallel converter and the balanced modulation, respectively. Each filter limits the frequency of the PCM signal output from the serial-to-parallel converter to a pass band of 1 MHz to 3 MHz. The power spectrum of the PCM audio signal has a relatively high frequency component. These components are removed by a low pass filter. Thus, for example, if the corresponding bits in the data streams ai 'and bi' are 1 and 0, then the ai 'bits are greater than 1 after passing through each low pass filter as a result of the removal of the high frequency components. It tends to be small. Therefore, the value of tan ^-1 (cos bi'π / cos ai'π) is slightly less than 3π / 4, resulting in a phase error at this point. As a result, the error rate becomes high, making recording of PCM audio data difficult.

According to the present invention, two low pass filters are replaced with one band pass filter 360. The 0-QDPSK modulated signal Sq is supplied from the addition circuit 355 to the band pass filter 360. The band pass filter 360 has the frequency characteristic shown in FIG. 3, and is formed between the frequency bands of the luminance component Y and the color component C as shown in FIG. The 0-QDPSK modulated signal Sq is limited to a specific frequency band limited to a bandwidth of 3 MHz.

The filtered signal is supplied to the PCM head unit 370, and recorded by the rotating magnetic heads 375 and 380 in the inclined track of the magnetic tape 100, each inclination track comprising a field of video signal. .

In the above-described embodiment of the present invention, band pass filter 360 is provided after balanced modulators 345 and 350. Thus, as described above, accurate 0-QDPSK modulation operation is performed without phase error to record PCM audio data of reduced error rate. In addition, since the PCM audio signal recording system described above uses one band pass filter instead of two low pass filters of the conventional system, the manufacturing cost of the VTR is reduced.

A system 400 according to the present invention for reproducing either a frequency modulated (FM) audio signal or a pulse code modulated (PCM) audio signal will be described with reference to FIG. The system 400 identifies whether the audio signal picked up by the rotating magnetic head from the magnetic tape 100 is a frequency modulated (FM) audio signal or the 0-QDPSK modulated PCM audio signal described above and reproduces them appropriately. The recording operation of the FM audio signal will be described in detail below, but the FM audio signal is input from the input line 402 to the system 400 as left and right AFM signals.

The PCM audio signal appearing on the input line 401 is dividedly supplied to the quadruple frequency multiplier 450 and the 0-QDPSK demodulator 410 included in the PCM audio signal reproducing unit 405. The quadruple frequency multiplier 450 multiplies the frequency of the received signal by four to provide a signal having a fundamental frequency of 8 MHz supplied to the phase shift comparator 455 and the band pass filter 465. Filter 465 has a relatively narrow band with a center frequency of 8 MHz. The output Cp of the band pass filter 465 is supplied to the level detector 480 which provides the system controller 110 with a corresponding detection output signal Lp of a relatively high level.

The AFM audio signal input from the line 402 is also divided so that one branch is supplied to the contact 430a of the switch section 430, which will be described later, and the other branch is divided again to the band pass filter 470, 475. Supplied. The band pass filter 470 has a pass band of the center frequency of 1.3 MHz corresponding to the frequency of the left AFM signal, and the band pass filter 475 corresponds to the frequency of the right AFM signal, as shown in FIG. It has a passband center frequency of 1.7 MHz. Band pass filters 470 and 475 provide signals C _L and C _R to level detectors 485 and 490, respectively. Each of these level detectors provides a relatively high level of detected output signals L _L , L _R to system controller 110.

When the PCM audio signal is recorded on the magnetic tape 100, the band pass filter 465 provides the signal Cp to the level detector 480, and the band pass filters 470 and 475 respectively supply the level detector 485,. 490) does not provide any signal. Thus, level detector 480 provides high level signal L _P to system controller 110, and level detectors 485 and 490 provide relatively low level signals L _L and L _R. Alternatively, when the AFM signal is recorded on the magnetic tape 100, the band pass filters 470, 475 do not provide any signal to the level detector 480, and the band pass filters 470, 475 Signals C _L and C _{R are} provided to level detectors 485 and 490, respectively. Accordingly, the level detector 480 provides a signal L _P having a low level to the system controller 110, and the level detectors 485 and 490 provide the high level signals L _L and L _R to the system controller 110. To provide.

In addition, when both AFM and PCM signals are recorded on the magnetic tape 100, the band pass filters 465, 470, 475 pass the signals C _P , C _L , C _R to the level detectors 480, 485, 490. To each. These level detectors all output high level signals L _P , L _L , L _R to the system controller 110. In this case, the system controller 110 determines whether to reproduce the AFM audio signal or the PCM audio signal based on the so-called playback mode signal supplied through the line 10 as described below.

The regeneration mode signal indicative of the AFM regeneration mode or the PCM regeneration mode may be applied to line 10 from a user-operated switch (not shown) that can be manually switched between the position corresponding to the AFM regeneration mode and the PCM regeneration mode. When the AFM regeneration mode signal is input or during the AFM signal regeneration operation, when the level detector 480 provides the low level L _P signal and the level detectors 485 and 490 provide the high level L _L and L _R signals, The system controller 110 outputs the signal Qs at a high level. However, if the switch is set manually so that the PCM playback mode signal is input to the controller 110, but the VTR does not initiate the PCM playback operation, in other words, the PCM playback mode signal is provided, but a non-PCM (AFM) program is provided. If you are currently playing at VTR and the level detector 480 is providing a low level signal L _P , and the level detectors 485, 490 are providing a high level signal L _L, L _R , System controller 110 will still output a high level signal Qs.

Similarly, during the PCM regeneration operation, the level detector 480 provides the high level signal Lp to the system controller 110. The system controller outputs a signal Qs having a relatively low level even when the reproduction mode signal applied to the input line 10 is an AFM reproduction mode signal. In other words, the VTR according to the present invention automatically determines whether the magnetic tape 100 to be reproduced contains AFM or PCM data, and optionally sets the reproduction mode signal received via the input line 10. Ignore

The signal Qs output from the system controller 110 is supplied to the switching circuit 430 as a control signal. When the level of the signal Qs is low, the movable contact 403c of the switching circuit 430 couples to the contact 430b connected with the 0-QDPSK audio signal reproduction system 405, while the signal Qs Is at a high level, the movable contact 403c couples to a contact 403a connected to the AFM signal input line 402.

However, when the AFM and PCM data are recorded on the magnetic tape 100 being reproduced, only the left and right AFM signals when the AFM signal reproduction mode signal is input to the line 10 to establish the AFM signal reproduction mode. Is played. In such a case, the movable contact 430c is coupled with the contact 430a to supply the AFM audio signal input from the line 402 to the audio signal output terminal 11, and the AFM signal from this terminal 11 is an amplifier. And the like through a loudspeaker (not shown).

On the other hand, when the PCM signal reproduction mode signal is input to the line 10 to establish the PCM reproduction mode, only the PCM audio signal is reproduced. That is, in the case where both PCM and AFM audio signals are recorded on the magnetic tape 100, for the PCM playback mode signal, the mobile contact 430c is coupled with the contact 430b, so that the PCM audio signal is either PCM or 0. QDPSK is transmitted from the audio signal reproducing system 405 to the output terminal 11 and reproduced by a loudspeaker (not shown) through an amplifier or the like.

In general, a PCM or 0-QDPSK audio signal reproduction system includes a 0-QDPSK modulator 410, an error correction circuit 415, a D / A converter 420, a muting circuit 425, a phase shifter 435, A quarter frequency multiplier 440, a voltage controlled oscillator 445, a phase comparator 455, a low pass filter 460, and a quadruple frequency multiplier 450. After passing through the multiplier 450 as described above, the quadrupled signal pa having a center frequency of 8 MHz is supplied to one of the input terminal of the band pass filter 465 and the phase comparator 455. . Phase comparator 455 is part of a phase locked loop (PLL) further comprising a low pass filter 460 and a voltage controlled oscillator 455, the voltage controlled oscillator 455 having a center oscillation frequency of 8 MHz and a low pass Controlled by the signal output from the filter 460, the oscillation output signal Co is provided to another input terminal of the phase comparator 455. The phase comparator 455 compares the phase of the quadrupled signal Pa with the phase of the oscillator 445, and outputs an output signal representing the relative phase through the low pass filter 460 as the oscillation frequency control voltage. Provided at 445. In the steady state, the frequency of the oscillation output signal of the voltage controlled oscillator 445 corresponds to the frequency of the signal Pa multiplied by four, all of which are 8 MHz.

The oscillating output signal Co having a frequency of 8 MHz is fed from the voltage controlled oscillator 455 to the quarter multiplier 440 and reduced to one quarter of the original frequency. Therefore, the quarter multiplier provides a signal C1 with a frequency of 2 MHz. A carrier signal having a frequency of 2 MHz is provided based on the 0-QDPSK modulated signal of the audio signal read out from the magnetic tape. Carrier C1 is supplied to phase shifter 435 to be shifted by [pi] / 2, thus providing carrier C2 having a phase difference of [pi] / 2 when compared with the phase of carrier C1. Carriers C1 and C2 obtained by the above method are supplied to 0-QDPSK demodulator 410. The 0-QDPSK demodulator 410 demodulates the PCM by demodulating the 0-QDPSK modulated audio signal supplied from the input line 401 using the carriers C1 and C2 according to a typical 0-QDPSK demodulation principle, which is well known in the art. Provide audio digital data Da '.

Data Da 'from the 0-QDPSK demodulator 410 is supplied to an error correction circuit 415 for error correction. The error correction circuit 415 provides the error corrected PCM audio digital data Da to the D / A converter 420 and also outputs an error rate signal De indicating the error rate in the PCM audio digital data. To provide. The system controller 110 outputs a muting error signal Qm to the muting circuit 425 when the error rate indicated by the error rate signal De is equal to or greater than the reference value.

The error corrected PCM audio digital data Da is supplied to the D / A converter 420, converted into an audio analog signal _{Sa a} , and then output to the muting circuit 425. Muting circuitry (425) in response to a muting control signal (Qm) from the system controller 110 to mute the audio analog signal (S _a2). Thus, the muting control signal (Qm) is, when not applied to the muting circuit 425, or when the error rate indicated by the error rate signal (De) less than the reference value, an audio signal (S _a2) is a muting circuit 425 and the switching Appears to the audio signal output terminal 11 through the circuit 430.

It can be seen that the FM and PCM audio signal reproducing system 400 according to the present invention operates to automatically identify the type of recording method used for the audio signal recorded on the magnetic tape and to reproduce the recorded signal appropriately.

Now, a program or sequence of logic steps executed by the system controller 110, such as, for example, a microcomputer, will be described with reference to the flowchart of FIG.

After commencement of the program in step 500, the routine proceeds to decision step 505, wherein the routine proceeds to a decision step 505, whereby the reference value of the level of the output signal L _P , L _L , L _R from all of the level detectors 480, 485, 490 is exceeded. It is determined whether it is higher or lower. If a response of YES is obtained in step 505, the routine proceeds to decision step 510, where it is determined whether the AFM signal regeneration mode is valid. If a yes response is obtained in step 510, the routine proceeds to step 515, where it is determined whether the flag F is one. If the flag F is not 1, i.e., F is 0, the routine proceeds to step 520, whereby the control signal Qs having a high level is output to the switching circuit 430, thereby moving the mobile contact 430c. Is coupled with the contact portion 430a. The routine then proceeds to step 525 where the flag F is assigned a value of 1, after which the routine proceeds to step 530 and returns to step 500.

If in step 510 a NO response is obtained, i.e. not in the AFM signal regeneration mode, the routine proceeds from step 510 to decision step 540 to determine whether flag F is one. Is determined. If a yes response is obtained in step 540, i.e., F = 1, then step 545 is executed, whereby a control signal Ss having a low level is outputted to the switching circuit 430 and moved. The contact portion 430c is coupled with the contact portion 430b. Next, the routine proceeds to step 550 where the flag F is assigned a value of zero and the routine proceeds to the next decision step 555. Alternatively, if flag F is not 1 in step 540, ie F = 0, the routine proceeds directly to step 555 in step 540.

At decision step 555, it is determined whether the error rate indicated by the error rate signal De from the error correction circuit 415 is smaller than the reference error rate value RPe. If yes, then step 560 is executed to determine whether flag G is one or not. If the answer is yes, i.e., G = 1, the muting control signal Qm is output to the muting circuit 425, and then in the next step 565 the output of the muting control signal Qs is stopped. The routine then proceeds to step 570 where the flag G is assigned a value of zero, and then step 530 proceeds to step 500. Alternatively, if a no response is obtained at step 560, that is, if flag G is zero, the routine proceeds directly to step 530 and returns to start step 500.

Alternatively, if at step 555 it is determined that the error rate De is greater than or equal to the reference error rate RPe, the routine proceeds to step 575 to determine whether the flag G is 1 or not. Is determined. If the answer to step 575 is no, the routine proceeds to step 580 and outputs a muting control signal Qm. Next, step 585 is executed, the flag G is assigned a value of 1, and then the routine returns to step 555. Alternatively, in step 575, if a towing response is obtained, ie, G = 1, the routine returns directly to step 555.

On the other hand, if it is determined in step 505 that at least one of the output signals L _P , L _L , L _R is not greater than or equal to the reference value R _F , then the routine proceeds to decision step 535, where the output Determines whether signal L _P is equal to or greater than reference value R _F. If in step 535 an acknowledgment is obtained, the routine proceeds to step 540, and in step 535, if an acknowledgment is obtained, i.e. L _P R _F , the routine proceeds to step 515 do.

The embodiment described above relates to a VTR for reproducing an information signal recorded on a magnetic tape as a 0-QDPSK modulated signal and / or an AFM signal. However, the present invention is not limited to this type of signal. That is, information signals other than the 0-QDPSK type modulation signal and the AFM type signal can be appropriately reproduced by the apparatus according to the present invention.

As is apparent from the above description, the frequency modulated audio signal and PCM audio signal reproducing system according to the present invention can automatically identify various kinds of modulated signals recorded on magnetic tape, and can reproduce them appropriately. Therefore, the system according to the present invention is used on a magnetic tape on which an FM audio signal or a PCM audio signal or a combination of these FM and PCM audio signals is recorded to reproduce such a recorded audio signal.

Referring now to FIG. 7, the FM audio signal recording and reproducing system used in accordance with the present invention uses the audio signal input from the input line 605 as a left AFM signal having a frequency band as shown in FIG. And an FM modulator 620 that modulates the right AFM signal. These modulated AFM signals are recorded by the AFM head unit 610 in one track corresponding to one field on the magnetic tape. Since the structure and function of the head unit 610 are similar to the structure and function of the video head unit 250 described above, further description of the unit 610 will be omitted.

The FM audio signal playback portion of the system includes a band pass filter 630, a limiter 635, and an FM demodulator 640. As described above, the FM modulated audio signal including the left AFM signal and the right AFM signal recorded on the tape 100 is read by the FM head unit 610, and the band pass filter 630 and the limiter 635. , And FM modulator 640, after which the final AFM signal is applied to input line 402 of FIG. 5 and reproduced by the above-described FM and PCM audio signal reproducing system according to the present invention.

Now, a signal recording system according to the present invention for recording video signals, PCM signals, and / or FM signals will be described in detail with reference to FIG.

Such a signal recording system according to the present invention may include various operating modes that selectively operate to record one or more video signals, a PCM audio signal (0-QDPSK signal), and an FM audio signal, for example, as shown in Table I. Have For example, in recording mode A, video, PCM and FM signals can all be recorded on a magnetic tape, and in recording modes B through D, only two signals indicated by [0] can be recorded on the tape, respectively. In the recording modes E to G, only one signal indicated by [0] can be recorded on the tape.

The signal recording system of FIG. 8 which selectively records a combination of a video signal, a PCM audio signal, an FM audio signal, or any one of them includes a video head unit 250, a PCM head unit 370, and an AFM head. Unit 610, each corresponding to a video head unit shown in FIG. 1, a PCM head unit in FIG. 2, and an AFM head unit in FIG.

The write amplifiers 282, 286, 371, 372, 611, 612 are connected to the system controller 110, respectively. The mode selection switches 710, 715, 720 are system controllers that respectively transmit signals for controlling the recording of video and / or PCM and / or AFM signals in response to the selection operation of the switches 710, 715, 720. 110). The mode select switches 710, 715, 720 coupled to the system controller 110 may, for example, title video signals, PCM signals, and FM signals, respectively, in Table I to establish recording modes A through G. It is closed when indicated by the symbol [0] in the column.

System controller 110 provides suitable control signals to write amplifiers 282 and 286, 371 and 372, 611 and 612, so that these signal lines for their corresponding rotating magnetic heads are on or in response to the control signals. Is off. Therefore, depending on the switching operation of the switches 710, 715, 720, the recording operation corresponding to the recording modes A to G shown in Table I can be executed.

The magnitude of the recording current for the video signal, the PCM signal, and the AFM signal is changed by one mode selected from the recording modes A to G. The recording currents Is, Iq, Ia (FIG. 9) flowing through the rotating magnetic head for recording the video signal, the PCM signal, and the AFM signal are each independently of the selected one of the recording modes A to G. As shown in FIG. 9, the following relationship is defined.

Ia Iq Is

The recording currents Ia, Iq, Is used in the recording modes B to D are larger than the recording currents used in the recording modes E to G, whereas the recording currents Ia, Iq, Is used in the recording mode A are recorded. Greater than the current used in modes B through D.

In the normal recording mode, the magnitudes of the recording currents Ia, Iq, and Is are larger than in the long time recording mode, and the tape speed decreases. The current magnitude relationship between the write currents Ia, Iq, Is is maintained not only during the recording in the normal recording mode but also during the recording in the long time recording mode or the low speed recording mode. The system controller 110 provides control signals to the write amplifiers 282 and 286, 371 and 372, 611 and 612 to control the magnitude of the write currents Ia, Iq and Is, respectively.

Therefore, during recording in the recording mode A, the AFM signal is recorded by each AFM head in each slope track corresponding to one field. The PCM signal is also superimposed on the recorded AFM signal by the PCM head. The video signal is also superimposed on the recorded AFM and PCM signals by the video head. In order to execute the above-described write processing, the write current of the signal is set in the relationship shown in FIG. Due to such a relationship of the recording current, as also shown in FIG. 10, the AFM signal is recorded in the deep portion 810 of the magnetic layer of the tape 100, the PCM signal is recorded in the intermediate layer 820, and the video signal. Is recorded in the surface layer or shallow layer 830.

The FM audio signal and PCM audio signal reproduction system described above with reference to FIG. 5 reproduces the FM audio signal or the PCM audio signal. Thus, as shown in FIG. 8, by using the VTR according to the present invention, FM and PCM audio signals representing the same program are recorded on the tape. This feature allows the magnetic tape recorded by the VTR using the present invention to be played back in a VTR that plays back only an FM audio signal, or alternatively in a VTR that plays back only a PCM audio signal.

In the recording mode B of Table 1, the PCM signal is recorded in a layer deeper than the video signal recorded closest to the surface. In recording mode C, an AFM signal is recorded in the deeper layer and the video signal is recorded as in mode B. In recording mode D, an AFM signal is recorded in the deeper layer, and the PCM signal is recorded at the nearest surface.

In addition, in the recording modes E to G, a single signal which is an AFM signal, a PCM signal, or a video signal is recorded on the magnetic tape layer corresponding to the recording current specified for the type of signal.

Since the video signal is not recorded during recording in modes D, F and G, servo control is performed while recording of one or both of the FM and PCM audio signals is performed based on the sync signal suitably provided by the video tape recorder. Is executed.

Since the magnitudes of the write currents Ia, Iq, Is of the video signal, the PCM signal, and the FM signal are controlled to provide the relationship shown in FIG. 9, the signal-to-noise ratio for each signal is significantly improved. Thus, for example, the error rate of the PCM audio signal can be reduced. In addition, in the write operation, the signal appearing in the various signal input lines shown in FIG. 8 is detected to provide the system controller 110 with another indication of the presence of the input signal. The system controller 110 also automatically controls or establishes the various recording modes A to G, for example, in response to the operation of the mode selection switches 710, 715, 720, rather than in response to the operation of various input signals. The operation is performed based on the display and the like.

Although specific embodiments of the invention have been described in detail with reference to the accompanying drawings, the invention is not limited to the specific embodiments described above, but various modifications and variations are defined in the appended claims. It can be implemented by those skilled in the art within the scope or intention of the present invention.

Claims (22)

Playback means for reproducing an information signal recorded on a recording medium and including at least one of first and second signals having different first and second formats, respectively, and detecting the first signal from the information signal; First detection means operative to provide a first detection signal indicative of the presence of the first signal, detecting the second signal in the information signal, and providing a second detection signal indicative of the presence of the second signal; Second detection means operable to operate, signal output means, switching means for selectively supplying the first signal and the second signal from the reproducing means to the signal output means, and the first through the signal output means. And control means for controlling said switching means in response to said first and second detection signals to selectively output a signal and said second signal. 2. The apparatus of claim 1, further comprising reproducing mode selecting means for selecting a first reproducing mode in which the first signal is reproduced and a second reproducing mode in which the second signal is reproduced, wherein the switching is performed by the control means. Means for outputting one of the first and second signals selected by the reproduction mode selection means if the information signal includes both the first signal and the second signal. The apparatus of claim 1, wherein the first signal is an FM audio signal and the second signal is a PCM audio signal. 4. The apparatus according to claim 3, further comprising recording means for recording the PCM and FM audio signals on the recording medium with respective recording currents of different predetermined magnitudes. 5. The method of claim 4, wherein the PCM audio signal is recorded in a first magnetic layer of a magnetic tape, the FM audio signal is recorded in a second magnetic layer of the magnetic tape, and the first and second magnetic layers are connected to each other. The device is superimposed on it. 6. The PCM audio signal according to claim 5, wherein the PCM audio signal is recorded in a first magnetic layer of a magnetic tape, the FM audio signal is recorded in a second magnetic layer of the magnetic tape, and the first and second magnetic layers are connected to each other. The device is superimposed on it. 6. The apparatus of claim 5, wherein the second magnetic layer in which the FM audio signal is recorded is disposed below the first magnetic layer in which the PCM audio signal is recorded. 6. The recording apparatus according to claim 5, wherein the recording means comprises: a phase modulation circuit for the PCM audio signal having separation means for separating the PCM audio signal into a first data stream and a second data stream; A first supply modulator for supplying first and second carriers to a first balanced modulator, a second balanced modulator for receiving the second data stream, and the first and second balanced modulators, respectively; A carrier supplying means in which the phase of the carrier is relatively shifted by a predetermined amount, an adder for adding an output signal from the first balanced modulator to an output signal from the second balanced modulator, and receiving an add signal from the adder A device comprising a band pass filter. 4. The apparatus according to claim 3, wherein the information signal further comprises a video signal having a third format different from the first and second formats, and reproducing the reproducing means or the video signal, wherein the control means is configured to reproduce the video signal. Controlling said switching means in accordance with a first and a second detection signal and causing said signal output means to selectively output said video signal together with one of said PCM audio signal and said FM audio signal. 10. The apparatus according to claim 9, further comprising recording means for recording the video signal, the PCM signal, and the FM signal on the recording medium with respective recording currents of different predetermined magnitudes. 11. The recording medium of claim 10, wherein the recording medium is a magnetic tape, the FM audio signal is recorded in a first magnetic layer of the tape, the PCM audio signal is recorded in a second magnetic layer of the tape, and the video signal is The first, second, and third magnetic layers recorded on the third magnetic layer of the tape, and the relationship between the write currents of the predetermined magnitude for recording the video signal, the PCM signal, and the FM signal in the respective layers. According to the device arranged in series with respect to the outer surface of the magnetic tape. 12. The apparatus of claim 10, wherein the magnitude of the write current of the FM audio signal is greater than the magnitude of the current of the PCM audio signal, and the magnitude of the write current of the PCM audio signal is greater than the magnitude of the current of the video signal. 2. The apparatus of claim 1, wherein the first signal has a first frequency, the second signal has a second frequency different from the first frequency, and the first detection means comprises: the first signal of the first signal; A first band pass filter having a pass band through which frequencies can pass, and a first signal level detector for detecting the passage of the first signal through the first band pass filter, wherein the second detection means comprises: A second band pass filter having a pass band through which the second frequency of the second signal can pass, and a second signal level detector for detecting the passage of the second signal through the second band pass filter; Device. 2. The apparatus according to claim 1, further comprising: additional reproducing means for reproducing a third signal having a third format different from the first and second formats, and a first mode in which the first reproducing means reproduces the first signal; And reproducing mode selecting means for selecting the first reproducing means and a second mode for reproducing the second signal, wherein the switching means causes the switching means to make the information signal not only a third signal but also the first signal. And a second signal, when the third signal is outputted through the signal output means in accordance with one of the first and second signals selected by the reproduction mode selection means. An information signal recording and reproducing apparatus, comprising: recording means for recording an information signal including first, second, and third signals having different first, second, and third frequencies into a recording medium, and the recording medium; Reproducing means for reproducing the information signal from the first signal; first detecting means for detecting a first signal in the information signal and providing a first detection signal indicative of the presence of the first signal; Second detection means operable to detect a second signal and provide a second detection signal indicative of the presence of said second signal, a signal output means, and said signal to said first signal and said second signal from said reproducing means; Switching means for selectively supplying to an output means, and responding to the first and second detection signals to selectively output the first, third signals, and the second, third signals through the signal output means. And control means for controlling said switching means in response. 16. The apparatus according to claim 15, further comprising reproducing mode selecting means for selecting a first reproducing mode in which the first signal is reproduced and a second reproducing mode in which the second signal is reproduced, wherein the switching means is arranged by the control means. The first signal selected by the reproduction mode selecting means for outputting together with the third signal through the signal output means when the information signal includes the first signal and the second signal as well as the third signal; An information signal recording and reproducing apparatus which outputs one of the first and second signals. The information signal recording and reproducing apparatus according to claim 15, wherein the first signal is an FM audio signal, the second signal is a PCM audio signal, and the third signal is a video signal. The information signal recording and reproducing apparatus according to claim 17, wherein the recording means records the PCM audio signal, the FM audio signal, and the video signal on the magnetic tape with recording currents of different magnitudes having a predetermined relationship. 14. The apparatus according to claim 13, wherein said recording means comprises: a phase modulation circuit for said PCM audio signal comprising separation means for separating a PCM audio signal into a first data stream and a second data stream, and said first data stream receiving means. A carrier supply means for supplying a first balanced modulator, a second balanced modulator for receiving the second data stream, and first and second carriers to the first and second balanced modulators, respectively; Receiving the carrier supply means whose phase is relatively shifted by a predetermined amount, an adder which adds an output signal from the first balanced modulator and an output signal from the second balanced modulator, and an adder signal output from the adder An information signal recording and reproducing apparatus including a band pass filter. A video tape recorder comprising: signal source means for providing a first information signal, a second information signal, a third information signal, and a first write current of a predetermined value in a relatively deep layer in a magnetic coating on a magnetic tape; A first rotating magnetic head means for recording an information signal and a second rotating magnetic head means for recording the second information with a second writing current in a second layer of the magnetic coating portion, wherein the magnitude of the second writing current is equal to the above; The second rotating magnetic head means having a magnetic coating portion having a depth smaller than that of the first write current and having a depth shallower than that of the first layer, and transmitting the third information signal to the third magnetic coating portion. A third rotating magnetic head means for recording with a third write current in the layer, wherein the magnitude of the third write current is less than the magnitude of the second write current so that the third layer is substantially in the magnetic coating of the magnetic tape. A video tape recorder comprising said third rotary magnetic head means to be in surface. 21. The video tape recorder of claim 20, wherein the first information signal is an FM audio signal, the second information signal is a PCM audio signal, and the third information signal is a video signal. 4. A quaternary phase shift keying circuit, comprising: a separation circuit for separating an input PCM information signal into a first data stream and a second data stream, a first balanced modulator for receiving the first data stream, and the second data A second balanced modulator for receiving the stream and a carrier supply means for supplying a first and second carriers to the first and second balanced modulators, the phase of the second carrier being 90 [deg.] With respect to the first carrier; A band for receiving the carrier supply means, an adder for adding the output signal from the first balance modulator to the output signal from the second balance modulator, and a band for receiving the add signal output from the adder with a predetermined passband Fourth-order phase shift keying circuit including a pass filter.

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