JPH061523B2 - Magnetic recording device and magnetic recording / reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording device and a magnetic recording / reproducing device, and more particularly to an offset 4 in a deep portion of a magnetic layer of a magnetic tape.
Phase Differential PSK (Offset Quadrature Differential Phase)
Shift Keying: OQDPSK) and 4-phase differential PSK (QDPSK)
The present invention relates to a magnetic recording device and a magnetic recording / reproducing device for recording or reproducing a digital audio signal or a frequency-modulated FM audio signal modulated by a multi-phase PSK modulation method, and recording or reproducing a video signal in a surface layer portion. .

2. Description of the Related Art FIG. 8 is a block system diagram showing a magnetic recording / reproducing apparatus including a conventional magnetic recording apparatus and a reproducing system. In the figure, the color video signal coming into the input terminal 1 is the video signal processing circuit 2
Is converted into, for example, a frequency-division multiplexed signal of a low-frequency conversion carrier color signal and a frequency-modulated luminance signal, and then recorded on the magnetic tape 6 by the rotary heads 5a and 5b through the recording amplifier 3 and the switching circuit 4.

On the other hand, the input terminal ₇ L, ₇ left channel and incoming to the _R (L
ch) and right channel (Rch) audio signals are converted into pulse code modulation (PCM) signals by the digital signal processing circuit 9 and time-division multiplexed, and then the OQPSK modulator 10 uses the offset 4-phase PSK method. The data is modulated and further recorded on the magnetic tape 6 by the rotary heads 13a and 13b through the recording amplifier 11 and the switching circuit 12, respectively.

Here, the frequency division into the surface layer portion of the magnetic layer by the rotary heads 5a and 5b is performed on the audio track on which the OQPSK-modulated digital audio signal is recorded in the deep portion of the magnetic layer of the magnetic tape 6 by the rotary heads 13a and 13b. The multiplexed video signal is recorded by forming a video track.

At the time of reproduction, the frequency division multiplexed video signal reproduced from the video track by the rotary heads 5a and 5b is supplied to the video signal processing circuit 15 through the switching circuit 4 and the reproduction amplifier 14, respectively. After being converted into a signal, it is output to the output terminal 16.

On the other hand, the digital audio signal reproduced from the audio track by the rotary heads 13a and 13b includes a switching circuit 12, a reproduction amplifier 17, an equalizer 18, and an OQPS.
The digital signal processing circuit 20 is passed through the K demodulator 19 respectively.
D, after being converted into a reproduction PCM signal,
The A / A converter 21 restores the original analog audio signal, whereby the left channel reproduced audio signal and the right channel reproduced audio signal are separately output to the output terminals 22 _L and 22 _R.
And they are output at the same time.

As described above, in the conventional apparatus shown in FIG. 9, in the rotary head type deep recording VTR, the OQPSK modulated digital audio signal is directly recorded in the deep portion of the magnetic layer of the magnetic tape 6. This recording / reproducing apparatus has already been published in the literature (for example, Arai et al .: “A STUDY ON
THE DIGITIZATION OF AUD
IO SIGNALS FOR VIDEO TEPE
RECORDER ”, International Conference on Ac
oustics, Speech, and Signal Processing, p.29-33,198
6).

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described conventional apparatus, since the OQPSK-modulated digital audio signal is directly recorded on the magnetic tape which is a non-linear transmission system, intermodulation distortion occurs and at the time of reproduction, A noise spectrum, which was not present during recording, appears in the low-frequency conversion carrier color signal band.

Therefore, there is a problem that the color S / N is deteriorated due to the noise spectrum in the reproduction signal when the video tracks are reproduced by the rotary heads 5a and 5b.
Further, there is a problem that the error rate of the reproduced digital audio signal is deteriorated by the distortion due to the linearity of the tape in the reproduced signal during the reproduction of the audio track by the rotary heads 13a and 13b.

Further, in the conventional apparatus, the video software recorded with the FM audio signal cannot reproduce the audio. In the record dead tape industry, digital audio is recorded separately from the video software recorded with the FM audio. It is necessary to prepare video software, which is troublesome and uneconomical.

The present invention was created in view of the above points, and it is an object of the present invention to provide a magnetic recording device capable of reducing the noise spectrum and capable of recording an FM audio signal as well as the magnetic recording device. It is an object of the present invention to provide a magnetic recording / reproducing apparatus having a recording unit as a recording unit and having a reproducing unit that can also reproduce an FM audio signal.

Means for Solving the Problems A magnetic recording apparatus of the present invention is a magnetic recording apparatus of a deep layer recording system, comprising first modulating means for generating a digital audio signal and second modulating means for generating an FM audio signal. , Mixing means for frequency-division-multiplexing a digital audio signal and an FM audio signal, a bias superimposing circuit, and a recording means.

The recording means records the output signal of the bias superimposing circuit in the deep portion of the magnetic layer of the magnetic tape by using an audio rotary head whose azimuth angle is different from that of the video rotary head.

A magnetic recording / reproducing apparatus of the present invention is a magnetic recording / reproducing apparatus of a deep layer recording system, which has a reproducing means, first and second signal separating means, in addition to the same structure as that of the magnetic recording apparatus.
A first demodulation means for demodulating a digital audio signal, and an FM
And a second demodulation means for demodulating an audio signal.

The digital audio signal generated by the modulation means and subjected to the polyphase DPSK modulation or the offset polyphase DPSK modulation is frequency division multiplexed with the output audio signal of the FM modulation means and supplied to the bias superposition circuit, where the high frequency bias is applied. The signal is superimposed. The digital audio signal and the FM audio signal, which are taken out from the bias superimposing circuit and on which the high frequency bias signal is superposed, are supplied to the rotary head for audio by the recording means, and thereby recorded in the deep portion of the magnetic layer of the magnetic tape. .

Thus, the polyphase DPSK or the offset polyphase DPSK
Since the digital voice signal modulated by and the FM voice signal frequency-modulated are recorded together with the high frequency bias signal, the linearity is improved.

Further, the audio signal reproduced by the reproducing means is separated into the digital audio signal and the FM audio signal by the first and second signal separating means, respectively, and the digital audio signal is demodulated by the first demodulating circuit, The FM audio signal is demodulated in the second demodulation circuit.

As described above, since the digital audio signal and the FM audio signal can be used separately, a plurality of audio signals can be recorded and reproduced simultaneously.

Embodiment FIG. 1 is a block system diagram showing an embodiment of the device of the present invention. In the figure, a portion above the one-dot chain line A is a magnetic recording device (recording system), and a portion including a portion below A is a magnetic recording / reproducing device including a reproducing system.

To describe the present embodiment, a color video signal of the standard color system is input to the terminal 25, and the video signal processing circuit 26
Is supplied to. The video signal processing circuit 26 separates the luminance signal and the carrier color signal by a known means, and frequency-modulates the luminance signal (FM) obtained by frequency-modulating the carrier wave with this luminance signal.
Luminance signal), and the carrier color signal is subjected to low-frequency conversion to generate a low-frequency conversion carrier color signal, and both signals are frequency-division-multiplexed to obtain a signal having a frequency spectrum as shown in FIG. 2 (A). Is output. In FIG. 2A, I is an FM luminance signal, and its carrier frequency band is 5.4 MHz to 7.0 MHz. II
Is a low-frequency converted color carrier color signal, and its low-frequency converted color subcarrier frequency is approximately 629 kHz. The recording video signal is supplied to the video rotary heads 28a and 28b via the recording amplifier 27. Further, the video signal processing circuit 26 supplies the color video signal of the standard color system as it is to the sync signal separation circuit 29. The sync signal separation circuit 29 separates the vertical sync signal and supplies it to a servo circuit 30 described later.

A left channel signal (L ₁ ) and a right channel signal (R ₁ ) of an analog audio signal are input to the input terminals 31a and 31b.
Is supplied to the input terminals 68a and 68b, and the left channel signal (L ₂ ) of an analog audio signal different from this is supplied.
And the right channel signal (R ₂ ) is supplied. At this time, if the movable contacts of the switch means 69a and 69b are both connected to the a side, the analog audio signal supplied to the input terminals 31a and 31b will be recorded as both the FM audio signal and the digital audio signal. On the other hand, if the movable contacts of the switch means 69a and 69b are both connected to the b side, the analog audio signal supplied to the input terminals 31a and 31b is an FM audio signal, and the input terminal 6 is used.
The analog audio signal supplied to 8a and 68b is recorded as a digital audio signal. Therefore, in the latter case, for example, when recording a foreign language movie as the program source, the stereo sound including the original foreign language is recorded as the digital audio signal, and the Japanese dubbing sound is recorded as the FM audio signal with high sound quality. You can

Consider a case where both switch means 69a and 69b are connected to the b side. The left-channel analog audio signal and the right-channel analog audio signal that have entered the terminals 31a and 31b respectively are noise reduction (NR) circuits 70a and 7a.
0b to reduce the dynamic range to 1/2, pre-emphasis circuits 71a and 71b are provided with pre-emphasis characteristics, and limiters 72a and 72b are provided.
At, signals above a predetermined level are cut. The outputs of the limiters 72a and 72b are sent to the FM modulators 73a and 73b, where they are FM-modulated with carrier liquids of 1.3 MHz and 1.7 MHz, respectively, and passed to the mixer 75 after passing through the bandpass filters 74a and 74b.

Further, the left channel analog signal and the right channel audio signal which have respectively come into the terminals 68a and 68b have their sampling frequencies set to, for example, 47.952 after unnecessary high frequency components exceeding the audible frequency band are removed by the low frequency filters 32a and 32b, respectively. It is supplied to A / D converters 34a and 34b via sample and hold circuits 33a and 33b of kHz (= 48 kHz ÷ 1.001), where it is linearly quantized to 16 bits and then encoded to obtain a PCM voice signal. To be done. The PCM audio signals of the left and right channels are supplied to the encoder 35.

The encoder 35 has an even-numbered sample ES in one field period and an odd-numbered sample OS, and is shown in FIG.
The error detection and correction codes P and Q are generated in the format shown in FIG.

In FIG. 3 (A), data DATA1 and DATA2
Is a sample ES, OS respectively subjected to time axis compression and interleaving, and is a horizontal word unit (1
Data of each row (word is 8 bits) DATA1, DAT
The parity Q of 6 rows of 8 × 30 (= 8 × 6 × 5) bits is repeated by repeatedly performing a predetermined operation on each of 10 words of A2 (8 × 50 bits each). To get In addition, the encoder 35 performs a predetermined operation for 8 columns in the vertical direction, that is, for every 32 words of data DATA1, DATA2, and parity Q of 1 word (= 8 bits) in each row, and each column of 4 words has 8 × 40 bits. Parity P is generated.

Next, the data DATA1 and DATA2 and the parities P and Q are divided into eight columns of 36 words each, and immediately before each of the 36 words, each 8 bits (= 1 word as shown in FIG. 3B). ) Synchronization signal SYNC, identification signal ID,
Address signal ADDR, block parity signal PARI
TY is added to form a data block of 40 words in total. The synchronization signal SYNC indicates the start of each data block. The address signal ADDR indicates the order of each data block in the digital audio signal for one track (that is, 130 data blocks). The block parity signal PARITY is PARITY = IDADDR
This is a signal for error detection obtained in. Here, it is an addition operator modulo 2.

Data DATA1, DATA2 shown in FIG. 3 (A) in 130 data blocks of the data area shown in FIG. 3 (C).
And the parities P and Q are transmitted, but a preamble for clock recovery for 4 data blocks and a postamble for 2 data blocks are added before that.

In this way, the encoder 35 generates a digital audio signal having a signal format of a total of 136 data blocks (= 43520 bits) shown in FIG. 3 (C), and this is generated in one field period (= 1 / 59.94 seconds). To transmit. Therefore, the transmission bit rate of the digital audio signal is 2.6086.
(= 136 × 320 × 59.94) Mbps.

The encoder 35 is field-synchronized with the recorded video signal by the output signal of the servo circuit 30.

An offset four-phase differential PSK modulator (OQDPSK modulator) 36 converts the digital audio signal into a serial-parallel signal and outputs it as two code strings alternately.
Phase shift means for shifting one code sequence from each other by ½ of one time slot and two code sequences from the phase shift means are received as modulation signals, and their phases are 90 degrees with each other at a predetermined frequency fc.
A known balanced modulation means for separately modulating two carrier waves with suppressed carrier amplitude, and a synthesis circuit for synthesizing two amplitude-modulated waves from the balanced modulation means and outputting a digital voice signal subjected to OQDPSK modulation. It is configured.

The carrier frequency fc is, for example, a horizontal scanning frequency f.
It is selected to be about 3.0 MHz, which is 191 times the frequency of _H. Therefore, the frequency spectrum of the output digital audio signal of the OQDPSK modulator 36 is the carrier frequency fc.
At the maximum level, and the transmission bit rate is 2.60.
Since it is 86 Mbps, ± n × 1 for the carrier frequency fc.
0 at a frequency position 30 MHz (= 0.6086 MHz / 2) apart
It becomes a known comb-shaped spectrum. However, the above n is a natural number.

Therefore, the output digital voice signal of the OQDPSK modulator 36 has a band limit for removing unnecessary frequency components, and is about 3.0 M which does not cause intersymbol interference.
The pass band width is 0.
After passing through the bandpass filter 37 selected about 7 times, the second
After being band-limited to a digital voice signal having a frequency spectrum as shown by III in FIG. 3B, it is input to the mixer 75 via the terminal 38, frequency-division-multiplexed with the FM voice signal, and then to the bias superposition circuit 39. Is supplied where the high frequency bias signal is superimposed.

The bias superimposing circuit 39 is a circuit forming an essential part of this embodiment.
For example, the structure is as shown in FIG. 4 or FIG.
4 and 5, the same components as those in FIG. 1 are designated by the same reference numerals, and in FIG. 5, the same components as those in FIG. 4 are designated by the same reference numerals.

In the bias superposing circuit 39 shown in FIG. 4, in the adding circuit 45, a bias oscillator 46 is added to an audio signal obtained by mixing the OQDPSK-modulated digital audio signal from the terminal 38 and the frequency-modulated FM audio signal.
For example, a high frequency bias signal of 10.8 MHz is superposed, and the superposed signal is output to the terminal 40 through the recording amplifier 47.

On the other hand, the bias superposition circuit 39 shown in FIG.
The OQDPSK-modulated digital audio signal and the frequency-modulated FM audio signal from
After being taken out through the trap circuit composed of the capacitor 51 and the capacitor 51, the high frequency bias signal taken out from the bias oscillator 46 through the capacitor 52 is added and combined (superposed), and then output to the terminal 40.

The circuit shown in FIG. 5 has a well-known circuit configuration for bias recording. The trap circuit blocks the transmission of a high-frequency bias signal to the recording amplifier 47 side, and also the capacitor 52.
Thus, transmission of the digital audio signal and the FM audio signal to the bias oscillator 46 side is blocked. The recording amplifier 47 of the bias superimposing circuit 39 shown in FIG. 5 can use an inexpensive recording amplifier as compared with the expensive recording amplifier of wide band and high output required in the bias superimposing circuit 39 shown in FIG.

The above-mentioned superposed recordings taken out from the terminal 40 are supplied to the rotary heads 41a and 41b for voice of FIG. 1, respectively.
The rotary heads 41a and 41b for voices are mounted on the rotary surface of a rotary cylinder (not shown) so as to face each other by 180 °, and
The rotary heads 28a and 28b for video are mounted at a fixed angle ahead of the mounting positions. The azimuth angle of the rotary heads 41a and 41b for audio is + 30 ° on one side and -30 ° on the other side, and the azimuth angle of the rotary heads 28a and 28b for video is + 6 ° on one side.
The other is selected to be -6 °.

The motor (not shown) that rotates the rotary cylinder is
Based on the output signal of the servo circuit 30 to which the vertical synchronizing signal from the synchronizing signal separating circuit 29 is supplied, it rotates in phase synchronization with the vertical synchronizing signal.

As a result, by the rotary heads 41a and 41b for voice,
The digital audio signal and the FM audio signal are high-frequency bias-recorded to a deep portion of the magnetic layer of the magnetic tape 43 which runs while being wound around the rotary cylinder over an angle range of a little over 180 ° to form an audio track, After that, the rotary head 28 for video is formed on the deep portion of the magnetic layer on the audio track.
A video signal for recording is recorded by a and 28b to form a video track.

At the same time, the control head 42 forms a control track along the longitudinal direction of the magnetic tape and records the control pulse generated from the vertical synchronizing signal extracted from the servo circuit 30.

Next, the operation of the reproducing system for reproducing the magnetic tape 43 recorded by the above recording system will be described. From the audio track formed in the deep portion of the magnetic layer of the recorded magnetic tape 43, the rotary heads 41a and 41b are used. The modulated digital audio signal and the FM audio signal which are alternately reproduced are preamplified by the preamplifier 55.
Is supplied to. At the same time, the video signal reproduced alternately by the rotary heads 28a and 28b from the video track of the magnetic tape 43 is supplied to the switching amplifier 56. Further, the control pulse reproduced by the control head 42 from the control track of the magnetic tape 43 is supplied to the servo circuit 30. The servo circuit 30 controls the rotation of the rotary cylinder so that the reproduction control pulse can be synchronized with the reference frequency signal.

The switching amplifier 56 amplifies the reproduced video signals of the rotary heads 28a and 28b and switches the reproduced video signals into a continuous signal, and supplies this signal to the video signal processing circuit 58 via the preamplifier 57. The video signal processing circuit 58 band-separates and extracts the FM luminance signal and the low-frequency-converted carrier color signal from the reproduction signal by a known means, performs FM demodulation to obtain the brightness signal, and obtains the carrier color signal by frequency conversion. The carrier color signal is superimposed on the luminance signal and output as a standard color reproduction color video signal from the terminal 59.

On the other hand, the preamplifier 55 amplifies the reproduced audio signal in which the digital audio signal and the FM audio signal from the rotary heads 41a and 41b are mixed and switches the amplified reproduced audio signal into a continuous signal, thereby reproducing the equalizer 80 and the band-pass filters 81a and 81a.
supply to b. The outputs of the band-pass filters 81a and 81b pass through the observed 82a and 82b, respectively, and FM demodulators 83a and 8b, respectively.
FM demodulation in 3b, de-emphasis circuit 84
After the de-emphasis characteristic is added at a and 84b, the dynamic range is restored to the original by the noise reduction circuits 85a and 85b, and the output terminals 86a and 86b.
The audio signals of the left channel and the right channel are extracted from b.

The reproduction equalizer 80 reinforces the attenuated high frequency component and then supplies it to the band pass filter 60. The reproduced modulated digital voice signal of the frequency spectrum shown in FIG. 2 (B) which is band-separated by the band-pass filter 60 is supplied to the OQDPSK demodulator 61 where it is subjected to the known OQDPSK demodulation to be a digital voice signal. It is supplied to the decoder 62.

The decoder 62 is supplied from the servo circuit 30 with a synchronization signal generated from a pulse phase-synchronized with the rotation of the rotary cylinder in order to know the first reproduction position of the digital audio signal of each track. The reproduced digital audio signal is subjected to processing such as error correction, time axis correction, time axis expansion and deinterleaving by the decoder 62, and each sample is combined in the same order as in A / D conversion, and the left channel And the right channel digital audio signal are separated.

The digital audio signals of the left and right channels are converted into analog signals by the D / A converters 63a and 63b, respectively, and then noise components generated at the time of D / A conversion are removed by the deglitcher circuits 64a and 64b. 65b
The unnecessary high frequency components exceeding the audible frequency band are removed by.
By this, the left channel to the terminals 66a and 66b,
The right channel analog audio signals are output separately.

Next, the noise spectrum low frequency effect according to the present invention will be described. As shown in FIG. 6, the OQDPSK-modulated digital audio signal I and the frequency-modulated FM audio signal II having a frequency spectrum of about 3.0 MHz ± 1.3 MHz are reproduced as in the conventional apparatus without superposing a high frequency bias signal. The recorded magnetic tape recorded directly on the magnetic tape in the deep layer of the magnetic tape by the rotary head for use and the video signal recorded on the surface of the magnetic layer is reproduced by the rotary head for audio. The frequency spectrums of the signal and the FM audio signal are as shown in FIG. 7 (A).

In FIG. 7 (A), fsc is a color subcarrier frequency of the low-frequency conversion carrier color signal, which is, for example, 629 kHz, and the low-frequency conversion carrier color signal band is caused by intermodulation distortion as shown by a broken line V. Since the noise spectrum exists at a large level and occurs in the low frequency region where the azimuth loss effect is reduced, it also occurs in the reproduced video signal of the video rotary head and deteriorates the color S / N. Further, such intermodulation distortion is caused by the non-linearity of the tape, and the distortion caused thereby deteriorates the error rate of the digital signal as described above, and the ratio of the carrier wave to the noise of the FM audio signal is reduced. It also deteriorates the C / N ratio shown.

On the other hand, the frequency spectrum O shown in FIG.
When the QDPSK-modulated digital audio signal and the FM audio signal are recorded by superimposing a high frequency bias signal of 10.8 MHz according to the present invention, the frequency spectrum of the reproduced modulated digital audio signal is shown in FIG. 7 (B). As a result, it is confirmed by an experiment that the noise spectrum in the vicinity of the low-frequency conversion color subcarrier frequency fsc among the noise spectrum due to the intermodulation distortion of the low-frequency conversion carrier color signal band surrounded by the broken line VI is significantly reduced. Was given. The high frequency components in FIG. 7 (B) are output by the reproduction equalizer to the second
It is equalized to the spectrum shown in FIG.

Further, instead of OQDPSK modulation, four-phase differential PSK modulation (QDPSK modulation) is used to directly perform deep recording on a digital audio signal having a frequency spectrum similar to that shown in FIG. 6, without superimposing a high frequency bias signal, and recording it. Similarly, in the frequency spectrum when reproduced, the noise spectrum in the vicinity of the low frequency conversion color subcarrier frequency fsc is significantly reduced.

Therefore, the present invention can be applied not only to the OQDPSK-modulated digital audio signal of the above-described embodiment but also to the QDPSK-modulated digital audio signal.

In addition to the OQDPSK and QDPSK modulation formats described above, the present invention is also applicable to 2-phase and 8-phase offset DPSK modulation and D-phase modulation.
The same can be applied to a PSK-modulated digital audio signal. Further, in the embodiment, the NTSC system color video signal is recorded in the video track as a predetermined signal form, but the present invention is the PAL system or SE.
The present invention can be similarly applied to a VTR of a deep layer recording system which records a CAM system color video signal as a predetermined signal form.

EFFECTS OF THE INVENTION As described above, according to the present invention, the digital audio signal modulated by the polyphase differential PSK or the offset polyphase differential PSK is mixed with the modulated FM audio signal, and is mixed with the high frequency bias signal in the deep portion of the magnetic layer. Since the recording is performed, the noise spectrum in the reproduced signal generated in the low-frequency conversion carrier color signal band due to the intermodulation distortion due to the non-linearity of the tape can be significantly reduced.
N, the error rate of the reproduced digital audio signal can be improved, and the reproduced FM
The S / N ratio of the audio signal can be improved, the compatibility characteristics of the magnetic tape can be improved, and both FM audio and digital audio can be recorded and reproduced at the same time. Therefore, two types of recorded tape software are available. The inconvenience of having to be solved can be solved.

Furthermore, FM audio and PCM audio can be used independently, and TV audio can be used as FM audio and compact disk (CD), digital audio tape (DAT) audio and FM as PCM audio. It is also possible to record broadcast sound at the same time, and it is possible to record and reproduce the original stereo sound as PCM sound in a foreign language source and the Japanese dubbed sound as FM sound with high sound quality. Has features.

[Brief description of drawings]

FIG. 1 is a block system diagram of an embodiment of the device of the present invention.
1 is a diagram showing an example of a frequency spectrum of a signal of each part of the block system shown in FIG. 1, FIG. 3 is a signal format diagram for explaining the operation of an encoder in the block system shown in FIG. 1,
4 and 5 are block system diagrams each showing an example of a bias superimposing circuit in the block system shown in FIG. 1, and FIG. 6 is a diagram showing an example of a frequency spectrum of a recording signal to an audio track, and FIG. 8A and 8B are views showing the frequency spectrum of the reproduced signal when deep recording is performed on the OQDPSK-modulated digital audio signal by the conventional device and the device of the present invention, and FIG. It is a block system diagram which shows an example of the conventional apparatus. 25 ... Color video signal input terminal, 28a, 28b ... Video rotary head, 31a, 31b ... Analog audio signal input terminal, 34a, 34b ... A / D converter, 35 ... Encoder, 36 ... OQDPSK modulator, 39 ... Bias Superimposing circuit, 41a, 41b ... Rotating head for voice, 43 ... Magnetic tape, 45 ... Addition circuit, 46 ... Bias oscillator, 47 ...
Recording amplifier, 50 ... Trap circuit coil, 51 ... Trap circuit condenser, 73a, 73b ... Frequency modulator, 74a, 74b, 81a, 81b ... Band filter,
75 ... Mixer, 80 ... Reproduction equalizer, 83a, 83b ... Demodulator (FM demodulator).

Claims (2)

[Claims] 1. An audio signal is recorded by a voice rotary head in a deep portion of a magnetic layer of a magnetic tape, and an azimuth angle between the voice rotary head and the voice rotary head is formed on the surface of the magnetic layer formed above the voice track. In a magnetic recording device for recording a video signal by forming a video track with different video rotating heads, a first modulation for generating a digital audio signal subjected to polyphase differential PSK modulation or offset polyphase differential PSK modulation Means, second modulating means for generating a frequency-modulated FM audio signal, frequency-division-multiplexing the output digital audio signal of the first modulating means and the output FM audio signal of the second modulating means. Mixing means, a bias superposition circuit for superposing a high frequency bias signal on the output audio signal of the frequency division multiplexing mixing means, and an output of the bias superposition circuit The magnetic recording apparatus, characterized in that said supplying as an audio signal to the audio rotary head, provided with a recording means for recording in the magnetic layer deep part No.. 2. An audio signal is recorded by a voice rotary head on a deep portion of a magnetic layer of a magnetic tape, and an azimuth angle between the voice rotary head and the voice rotary head is formed on a surface portion of the magnetic layer formed above the voice track. In a magnetic recording / reproducing apparatus for forming a video track by recording video signals with different video rotary heads, and reproducing the audio signal and the video signal recorded on the magnetic tape, multi-phase differential PSK modulation or Offset polyphase differential PSK first modulating means for generating a digital audio signal which is modulated, second modulating means for generating an FM audio signal which is frequency modulated, and output digital audio of the first modulating means Mixing means for frequency division multiplexing the signal and the output FM audio signal of the second modulating means, and a high frequency bias to the output audio signal of the mixing means for frequency multiplexing. A bias superimposing circuit for folding, a recording means for supplying an output signal of the bias superimposing circuit to the rotary head for audio as the audio signal and recording the signal in a deep magnetic layer portion, and a signal recorded in the deep magnetic layer portion. Reproducing means for reproducing, first signal separating means for separating the digital audio signal from the signal reproduced by the reproducing means, and second signal for separating the FM audio signal from the signal reproduced by the reproducing means. Separation means, first demodulation means for performing polyphase differential PSK demodulation or offset polyphase differential PSK demodulation on the digital audio signal separated by the first signal separation means, and separated by the second signal separation means. Second for demodulating said FM audio signal
And a magnetic recording / reproducing device.