JPS60157767A - Recording device - Google Patents

Abstract

PURPOSE:To prevent the generation of the crosstalk noise by switching alternately and every track the 1st and 2nd carrier frequencies which are out of an audible band together with the difference frequency also set outside the audible band to modulate the sound signal, modulating again the modulated sound signal with an optional frequency of a band between a chroma signal and a luminance signal to be recorded and mixing this modulated signal into the luminance and chroma signals for recording. CONSTITUTION:The sound signal is modulated by an FM modulator 61 to alternate tracks with a subcarrier of 30kHz or 60kHz. This modulated signal and a sound signal are mixed together by a mixer 64. This mixture signal is modulated again by an FM modulator 17 with a subcarrier of 1.5MHz. In a reproduction mode, the normal signals (solid lines) of a subcarrier of one side and the crosstalks (broken lines) of a subcarrier of the other side are mixed as shown in figures A and B for the signals supplied to an FM demodulator 67. Then the frequency of the subcarrier is set so that the beat frequency of said mixture is set out of a sound band. Thus it is possible to eliminate a noise component through an LPF47.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to a video tape recorder (VTR) in which an R voice f white signal is FM modulated and recorded together with a video signal.
ζRelating to a convenient recording device.

Background technology and its problems In addition to FM modulating the luminance signal in the video signal on the western side,
The chroma signal is low-frequency converted to frequency interleave between adjacent tracks, and can be recorded on slanted tracks on the tape without guard punts using two rotating heads with different forces and azimuth angles. I am here.

In such a VTR, audio signals have conventionally been recorded using a fixed head.
It was held at the ceremony.

However, in the case of the above-mentioned VTR, when the recording density has been increased, the tape transport speed has been made extremely slow, and in so-called 8 mm video, the tape transport speed has been reduced to about 1.4 cm/sec. For this reason, when recording audio signals, the relative speed between the fixed head and the tape becomes slow, making it impossible to record good audio signals.

FM modulate the sound of the sound in a band between the FM-modified luminance signal and the low-frequency converted chroma signal,
It was proposed to record the signal on an inclined track by superimposing it on the video signal.

That is, FIG. 1 shows an example of a so-called 8 mm video recording system. In the figure, a video signal from an input terminal (1) is supplied to a ζFM modulator (5) through an AGC amplifier (2), a pre-emphasis circuit (3), and a clamp circuit (4). , FM modulated so that the white beak is 5.4 Mllz
An M luminance signal YFll is formed. This signal YFM
is supplied to the mixer (7) through the bypass filter (6).

In addition, the video signal from the input terminal fL passes through the band pass filter (8) and the pre-emphasis circuit (9) and is supplied to the low-frequency conversion circuit II!8Q01 (with a subcarrier frequency of 7
A low frequency converted chroma signal CD of 43.44kllz is formed. This signal CD is supplied to the mixed and combined books (7) through a low-pass filter (11).

Furthermore, the audio signal from the input terminal (I2) is supplied to the ζ low-pass filter (14) through the AGC amplifier (13), and the band is limited to 15kllz or less. This signal is supplied to a ζr''M modulator (17) via a pre-emphasis circuit (15) and a limiter (16) to form an FM audio signal AFM with a center frequency of 1.5M1lzO.This signal AF11 1.5MIIz+ 100k
mixer (
7).

In addition, a pulse signal synchronized with the rotation from the rotating head drum (not shown) is transmitted through the terminal (19) to the multiplier (
20) to form a signal that goes around once in four trunks. This signal is a 4-frequency pilot signal forming circuit (2
1) approximately 102.54k for each track
llz, 118.95ktlz, 165.21kl
A pilot signal varying from lz to 148.69kllz is formed. This signal is fed to a mixer (7).

Therefore, from the mixture 4:i (71), for example, a frequency-multiplexed recording signal as shown in FIG. 2 is taken out.

Note that only one pilot signal is provided for each track.

Then, this recording signal passes through the recording amplifier (22),
The rotating heads (23a) and (2) have different azimuth angles.
Jb).

In this way, video signals and audio signals are recorded.

Furthermore, in order to reproduce the signal recorded in this way, the following procedure is performed, for example.

That is, in FIG. 3, the rotating head' (23a)
, (23b) are transmitted to the amplifier (31a),
(31b). This amplifier (31
The signal from a (31b) is supplied to a switch circuit (32), which is controlled by a -/sodo switch kJ knee from a terminal (33). The signal from this switch circuit (32) is transmitted to the bypass filter (34).
), the FM luminance signal YFM is taken out, and the signal is supplied to a limiter (35), an FM demodulator (36), and a de-emphasis circuit (37) to demodulate the YFM luminance signal. In addition, the signal from the S/F circuit (32) is supplied to the low-pass filter (38) to generate a low-frequency conversion chroma signal! The Pi-CD is extracted, and this signal is supplied to a high frequency conversion circuit (39), a de-emphasis circuit (40), and a bandpass filter (41), and a chroma signal is extracted. The luminance signal and chroma signal are mixed in a mixing circuit (42) to form a ``C video signal'' and sent to a video output terminal (43).
is output to.

Also, the signal from the switch circuit (32) has a center frequency of 1.
, 5 Mllz, and the FM audio signal AFM is extracted. This signal is passed through the limiter (45) if
! The audio signal Jd is fed to the D unit (46) and the ζ audio signal Jd is circulated i times. This audio signal is fed to the low-pass filter (47).

The signal from this low-pass filter (47) is l:'D
Pre-bold circuit for compensation to Sopuau 1 (48), low pass filter (49), de-emphasis circuit 11Ft
(5Q), outputs the output amplifier (5) to jJB and outputs it to the audio output device 11 (52).

Also, switch times 1 to 8 (the signal from 321 is
17 is supplied to the pullout detection circuit (53), and this detection number 14 is supplied to the hold circuit (48).

Furthermore, the signal from the switch circuit (32) is supplied to a pilot signal detection circuit (54), and four-frequency pilot signals are detected. The detection signal of each is fed to the tracking control number forming circuit (55), and a tracking control signal is formed according to the level of each Bi1:J signal. This control signal is passed through the terminal (56) to the Zaho circuit (
(not shown).

In this way, the video signal and the audio signal are reproduced.

In this case, the audio signal is converted to FM.
Since the rotary head records and reproduces the video signal together with the video signal, the audio signal does not deteriorate even if the tape transport speed is slowed down.

By the way, in this apparatus, the track pattern of the tape "2" during the recording process is as shown in FIG. 4A. In other words, the track pitch is, for example, 20
It is assumed to be μm. On the other hand, the head width is 1511m.
stipulated in Therefore, on Tape+, a spacing of approximately 5 μm is provided between adjacent tracks.

For this reason, during normal recording and reproduction, there is very little talk from adjacent trunks, and there is no risk of sound 'Bg;' being caused by the talk.

However, in this device, the tape running speed was set to 111
It was proposed to use a longer recording time, e.g. A, for example. In that case, the trunk pattern would be as shown in FIG. 4B. Zunawara track pitch is 10μ
m, and in order to record this with a 15 μm head, part of the track is erased by commercial recording, resulting in a width of 10 μl.
A trunk is formed. Follow this tape (!-1
11/i, crosstalk from adjacent trunks occurs because the head width is wider than the trunk width.

If the Kostalk is subtracted from the original reproduced signal in this way, for example, as shown in Figure 5, when there is an original signal (solid line) and a crosstalk component (broken line), As shown in FIG. 5B, this demodulated signal is the original audio signal (solid line) with twice f, (fWl is the audio band -
15 ktlz), the so-called triangular noise (dashed line) becomes slightly heated and becomes -C. '&
Triangular noise: i. It has a sufficiently high level even in the audio band, and its spectrum changes depending on the frequency and level of the recording signal of the adjacent track.
This was an extremely large factor in deteriorating sound quality.

OBJECTS OF THE INVENTION In view of these points, the present invention aims to prevent the generation of crosstalk noise with a simple configuration.

SUMMARY OF THE INVENTION The present invention intersects an audio signal with first and second carrier frequencies whose respective frequencies are outside the audible band and whose difference frequency is also outside the riJ audible band for each rank. -t
This modulated signal is transformed again at an arbitrary frequency in the band between the recorded luminance signal and chroma signal, and this re-modulated signal is mixed with the luminance signal and chroma signal. The present invention is a recording apparatus that records data using a simple structure, and can prevent crosstalk noise from occurring with a simple configuration.

About the example - ] Double 8mm video - ζ is FM Ondo fake -
Maximum debiecidin of 1I-1AFt+ is ±100kl
It is defined in lz.

Therefore, in FIG. 6, the signal from the limiter (16) is supplied to the second FM modulator (61). Also this F
The first and second carrier frequencies f1 and f2, for example 301c, are sent to the M-variant gllJ device (61), respectively, which are outside the IjJ auditory range and at the same time the difference frequency is also "+J @ outside the band.
Two subkeys, IIz and 60kl12, are supplied via a switch circuit (62). This switch circuit (62) is controlled by a -., soto switching signal from a terminal (63).

Furthermore, the signal from the FM modulator (61) and the limiter (16)
) is mixed with the original audio signal from the mixer (64);
This mixed signal is fed to the FM modulator 11+I (17). A carrier l of 1.5 Ml1z is fed to this FM modulator (17).

Although only the main part of the audio signal path has been explained above, the other parts are constructed in the same way as in FIG.

In this device (b), the voice (number N) whose band is limited to 15kllz or below is converted into an IM by an FM converter (61) to an alternating track with a subcarrier of 30kflz or 60kllz, and this The tlM signal and the audio signal are mixed. Therefore, as shown in FIG. If y.

A mixed signal is formed in which a signal C is changed by a subcarrier of 30kllz and a signal C is changed by a subcarrier of 60kllz at 60±15kllz. One is provided in each trunk.

Then, the mixed signal for each °C is sent to the FM modulator (17) ゛(,1
, 5M and 112 carriers, the angle is changed 8]M by 111 degrees.

The maximum deviation of Gogode FM audio signal 8 to M is ±
100kllz, so the above 60k
Change iiJ with tl z as a subcarrier! d6
It is also possible to record the signal C of 0±15 kHz as F M lit)M.

Furthermore, the signal recorded in this manner is reproduced as follows. In FIG. 8, FMiU611a
Vessel (46) Noi,! 8+1d output cassisoti times 1i'
A (65) is 1lri and Rovano, filter (47
) as well as the FMfjt i1M unit (46)
Revenge i)! It is supplied to a J ratio output bandpass filter (66) and a band from 15 to 75 k II z is extracted. The signal from this bandpass filter (66) is supplied to a second FM demodulator (67).

This FM demodulator (67) demodulates the signal modulated by the FM modulator (61). In this case, the signal modulated by the FM modulator (61) is The carrier has been changed to 30kllz and 60kHz.

For this reason, when FM demodulation is simply performed, variations in the subcarriers cause fluctuations in the DC component of the demodulated output.

The --- throat switching signal from the sogode terminal (33) is FMi.
The signal is supplied to a summer controller (67) and reversely corrected to remove fluctuations in the DC component.

The signal from this FMfM modulator (67) is then supplied to a low-pass filter (47) through a switch (65).

This is how shoshu takes place. And in this case, F
The signal supplied to the Mfiil1M unit (67) is the normal times 3+ (solid line) of one subcarrier in each trunk and the crosstalk of the other subcarrier ( (dashed line) are mixed. Here, the chronograph and talk noises are the beat frequencies of the two subcarriers. Therefore, by setting the subcarrier frequency so that this beat frequency is outside the audio band, this noise component can be removed by the low-pass filter (47).

That is, for example, as mentioned above, the audio band is 15 k 1
1z, subcarriers at 30kHz and 60k11
By setting it to z, the lowest B1-frequency becomes a difference component of 30 k II y, which can be easily removed by a low-pass filter (47) with a band of 15 k It z or less.

Furthermore, in the above-mentioned apparatus, since a redundant audio signal is provided in the band of 15 kllz or more, this band can be reproduced even in a model that does not have the above-mentioned circuit. Therefore, it is compatible with those models. Furthermore, when producing a tape recorded with a model that does not have the above-mentioned circuit, the switch (65) is connected to the FM demodulator (46).
By switching to the side, it is possible to reproduce bands of 15 k II z and above.

Furthermore, the circuit configuration of the playback machine is as shown in Figure 10.
30±15kllz bandpass filter (66a)
and (3Q:!: 15kl+2 band pass filter (
66b) are provided independently, and these outputs are connected to the terminal (33
) may be switched and taken out by a switch ([i8) that is switched by a signal from the FMf friend it+l unit (67). In this case, a signal from which crosstalk has been removed is taken out from the switch (6th) in the form of an FM wave.

Therefore, by supplying this signal to the dropout detection circuit (53), it is possible to compensate for dropout without the risk of malfunction due to talk.

In this way, the occurrence of crosstalk twist is prevented, and according to this device, the maximum deviation of the FM audio signal is effectively utilized, and the crosstalk twist can be prevented with an extremely simple configuration. It also maintains its strength and compatibility with other models.

Note that in the above-described apparatus, the second FM modulator (61) may be an AM modulator. In this case, improving the S/N by 1 degree using the carrier suppression force formula will further increase the effect.

Manoko In normal recording and playback, if crosstalk noise is small, the above-mentioned circuit can record and play back two channels of audio. In that case, 15 k I
For example, the stereo sum component, 30±15kllz, 60±15k If the main signal is the band from Iz to 1.
Compatibility with other models can be maintained by using the 411 region of z as the sub-I/H signal and using it as a stereo difference component.

This device can also be applied to a saw saw V'I''R in which the audio signal is I''M modulated and recorded deep in the magnetic layer of the °ζ tape using a head with a wide gap of 1 quotient.

ADVANTAGES OF THE INVENTION According to the present invention, it has become possible to prevent the crosstalk twist from occurring with a simple configuration.

[Brief explanation of the drawing]

Go to Figure 1. Figure 5 is a diagram for explaining the conventional device, and Figure 6.
The figure is a system diagram of an example of the present invention, and FIGS. 7 and 10 are diagrams for explaining the same. (17) is an FM modulator, (61) is a second Fll/l converter 1111d, (62) is a switch circuit, and (64) is a mixer. Figure 4 Figure 5 A B Figure 6 Figure 1 fl S, (4) 1x) −′〈 ÷

Claims (1)

[Claims] The first frequency, in which each frequency is outside the listening band, and the difference frequency is also outside the listening band. The second carrier frequency is modulated by alternating J1° for each trunk, and this modulated signal is mixed with the recorded luminance signal 743
A recording device that modulates the signal again at a frequency in a band between the signal and the signal, and records the re-modulated signal by mixing it with the luminance signal and the chroma signal.