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JPS54153002

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DESCRIPTION JPS54153002
Description 1, title of the invention
Angle modulated wave level automatic control method
3. Detailed description of the invention The present invention relates to an angle modulated wave
level automatic control method, in particular, a multi-channel record cutting method for
recording a multi-channel signal on a record disc by multiplexing a direct wave signal and an
angle f harmonic. In the recording system, by automatically controlling the level of the anglemodulated wave by exceeding the predetermined level corresponding to each frequency of each
channel signal of multi-channel, the * ws signal of the angle f1i1 wave is It is an object of the
present invention to provide a method which can improve the 8N ratio. In general, when a direct
wave signal and an angle modulated wave are multiplexed and a multi-channel signal is cut and
recorded on a record disc, when the recording level of the angle f harmonic is small, a
characteristic noise such as 7M noise at the time of pickup again The 8N ratio by-is not good.
That is, in this angle modulated wave transmission system, the 8N ratio of the angle modulated
wave is generally expressed by the following equation. However, in the equation (1), the highest
variation signal frequency, Δ fri frequency shift, C is the carrier level of the angle modulated
wave, and N is the noise level. From this, it can be understood that in the angle modulated wave
transmission system, it is better to have a large EndPage: 1 for the level of the angle modulated
wave in order to improve the SN ratio. However, when the angle modulated wave level is always
a dog, the head of the record cutter generates heat, which causes the problem of having to use a
special gas cooling means that is dog-friendly. Therefore, it is necessary to control automatically
according to the level fluctuation of the level of all the channel signals of the angle modulation
wave. Therefore, the present applicant has previously proposed a method as seen in Japanese
Patent Publication No. 49-14242 and Japanese Patent Publication No. 49-14243 as a carrier
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wave level automatic control method in a multi-channel record cutting and recording system. In
any of these proposed systems, the level of the angle f harmonic is automatically increased when
the level of the direct wave signal increases, and the SN ratio is deteriorated due to the
interference between the direct wave signal and the angle modulated wave, distortion rate
custom order Polish in a method that has the feature of reducing the deterioration of the Also,
the angle f to harmonic level automatic control method previously proposed by the present
applicant in Japanese Patent Application No. 49-109944 (JP-A-51-37203) is also effective when
the level of each channel signal is extremely small. In addition to the above features, the signalto-noise ratio of the demodulated signal is also improved by enhancing the level of the anglemodulated wave. However, in recording and reproduction of multi-channel records, in each of the
above-described proposed systems, if the high frequency component of the direct wave signal
becomes a dog above a predetermined level, the level of the angle fM wave will be increased to It
will increase the tracing distortion.
The reason is that the more the frequency to be recorded and reproduced in tracing distortion
becomes, and the larger the width of Ona, the approximate expression of the second harmonic
distortion of vertical tracing distortion (2) It can be easily understood from the equation. D ==
[xtoo 1%) (2) However, in (2) Formula V: linear velocity of sound binding (preparation / one), f:
frequency (H2) 1. The radius of curvature of the tip of the reproduction needle (scratch); From
the viewpoint of the interference of the direct wave signal with the angle-modulated wave by the
direct wave signal, the above-mentioned proposed system in which the tracing velocity amplitude
is further increased causes a further disadvantage that the phase modulation is completely
received. The equation (3) shows an approximate equation in which the angle modulated wave is
phase-modulated by the direct wave signal. However, in the equation (3), mp: modulation degree,
f: carrier frequency, etc. are the same as the equation (2). Therefore, in multi-channel recording
in which the direct wave signal and the angle-modulated wave are superimposed and recorded,
the angle is further increased even though the high frequency component of the direct wave
signal is increased and the level is large. It is not good from the example of the above equation
for enhancing the modulation wave. In addition, it has a% 相当 equivalent to 1 9 dB10 ct in the
high frequency signal region at the limit to the drive coil heat generation of the cutter head, and
it is severe to each of the above proposed methods even from the viewpoint of heat generation.
In order to achieve tube fidelity in view of the above points, set the level set point according to
the frequency to each multi-channel channel signal, and record the level of the angle modulated
wave at or below this level set point It is desirable to further improve the S / N ratio of the
demodulated signal of the f-harmonic to be enhanced by automatically enhancing within the
system. The present invention satisfies the above-mentioned essential parts, and one embodiment
will be described below with reference to the drawings. FIG. 1 is a block diagram of one
embodiment of the system of the present invention, and FIG. 2 is a circuit diagram of one
embodiment of the main part of FIG. In FIG. 1, each channel No. 15 of multi-channel is recorded
by magnetic tape at 1. Here, for convenience of explanation, for example, four channel signals of
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il'fOH + tOH2 + OH5 and CH4 are described as being recorded on the magnetic tape 1. The four
channel signals + Mi1 to CH4 recorded on the magnetic tape 1 are reproduced by the magnetic
head 2 and supplied to the @ sign processing circuit (arithmetic circuit) 31C, where, for example,
a sum signal (OH ++ OH2) and a difference signal (CiE + -CH2) and 7) 1] signal (OH, 10 OH,) and
difference signal (OHx-C!)
And H4). The output sum signal of the signal processing circuit 3 is supplied to the delay circuit
4 and is supplied to the mixing circuit 1 after being time-matched EndPage: 2 with the
companion difference signal line. The output difference signal of the signal processing circuit 3 is
supplied to the angle modulator 5, where the carrier wave of a predetermined frequency is anglemodulated to be an angle-modulated wave of a predetermined frequency band. This angle
modulated wave is supplied to the angle modulated wave level control circuit 6 and, as will be
described later, a predetermined level corresponding to the frequency set for each channel signal
reproduced from the magnetic head 2vC. VC is automatically increased when the level set point
is below. The level is controlled by the angle modulated wave level control circuit 6 and the fc
angle modulated wave is supplied to the mixing circuit 7 and mixed with the direct wave signal
from the delay circuit 4 so that the bands do not overlap. The output signal of the mixing circuit
1 is supplied through a cutter amplifier 8 to a cutter head 91C, which is then driven to be
recorded on a record disc (Lack board). The specific circuit configuration of the upper 6 pin
break angle modulation wave level control circuit 6 ≦ (explained later). FIG. 2 shows a circuit
system of an embodiment of the angle-modulated wave level control circuit 6 in which an OH +
channel signal a as shown in FIG. 3 (A) is input to the input terminal 10. The 0H20 channel
signal as shown in FIG. Channel signal a. b is a variable resistor 12,. The level is adjusted in 13,
and the buffer amplifier t4. After tsy, it is supplied to the equalizer circuit 16.17, where the
frequency characteristic as shown in FIG. 4 is given, and level setting according to the frequency
is made. In general, the representative characteristics of the noise distribution of the
reproduction and demodulation signal transmission system of a multi-channel record tend to
increase toward the high region with a slope of about 3 dBloCt from the mid region as shown in
FIG. It is a surface noise. Therefore, the characteristics of the equalizer circuits 16 'and 17 of the
present embodiment are set to the following ones with m-cut characteristics which are
attenuated by the slope of -3aBloct from the mid band to the high band as shown in FIG.
However, it is a matter of course that other variations of the above-mentioned equalizer%
characteristics can be considered because the energy distribution of the music signal to be cut
causes the noise to be a noticeable source or a non-prominent source. The above equalizer circuit
16. Channel signals a and b whose high frequency is attenuated and which are obtained from IT
are rectified circuits 111.1!
l and supplied to the buffer and waveform shaper 20.21 after being envelope-detected and
supplied to the threshold level set point or more and eIcha level, and L level when the level is
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smaller than this threshold level set point Figure 3 (C). (D) K is converted into a digital signal C, d
as shown. A large #Rm period in which the threshold level set point is exceeded by the digital
signal C, aa NAND gate 22 (a period indicated by ta for a channel signal a + IC shown in FIG. 3A).
As for the channel signal, the period shown by tb is 9 when the channel signal a and b are in
common during the period L) 9 and in the other period, it is H level as shown in FIG. It is taken
out as a digital signal e− shown and supplied to the integration circuit 23. The integration circuit
23 is selected to have a small attack time and a relatively large recovery time. The output signal
of the integration circuit 23 is applied as a control voltage to the voltage control amplifier 25
throughout the buffer amplifier 24 to control its amplification degree. On the other hand, in FIG.
2, reference numerals 26 and 2T denote angle modulated wave signal input terminals, and an
input terminal 26 has an angle of a carrier wave having a predetermined frequency, for example,
a difference signal (0H1-OH2) as shown in FIG. The angle modulated wave f of the
predetermined level obtained by modulation is applied, and the angle modulated wave of the
predetermined level obtained similarly by the affinity terminal 271CI-J difference signal (OR1OHa). Waves are being added. The angle modulated wave f is supplied to the voltage control
amplifier 2s through an increase of $ 1628, where it is level-controlled to the control voltage
from the buffer amplifier 24 so that the angle modulated wave g as shown in FIG. Be done. That
is, the level of the angle-modulated wave f is enhanced when one of the channel signals a and b is
less than a predetermined level set point, and both channel signals simultaneously exceed the
level set point, and the level is increased to the next level. It is output as an angle modulated
wave g as shown in Level Control 1lt-Receive as EndPage: 3 as shown in FIG. 3G) without being
enhanced as it is. This level control is provided by the equalizer circuits 16 and 17t, and the
channel signal must be provided; in the case of the high frequency, even if the level is not
enhanced when the channel signal has a frequency lower than the middle frequency, It will be
possible to raise the level. The angle modulated wave g taken out of the voltage control amplifier
25 passes through the amplifier 29 and is output from the output terminal 30 to the mixer 7
shown in FIG.
The angle modulated wave that has been input to the input terminal 21 is supplied to the voltage
control amplifier 32 through the amplifier 31 in the same manner as described above, where it
has exactly the same function as that described above. Then, after the bell control # is performed
according to the frequency of the OH ss 0 ILa channel signal from the terminal 38. 37, it passes
through the amplifier 331 and is taken out from the output terminal 3 (from the terminal. In the
above practical example, the level of the angle falll wave is enhanced when it becomes smaller
than the nine level set point according to the frequency of each multi-channel signal. The level
modulation of the angle modulation wave may be totally attenuated when it becomes larger, and
the point is that the level of the angle modulation wave when it becomes smaller than the above
level revision point is relative to that when the level set point becomes large It is recommended
that the Although the direct wave signal f is a sum signal of two channels and the modulation
signal of the angle modulated wave is a difference signal, the present invention is not limited to
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this. As described above, the angle modulated wave level automatic control method according to
the present invention provides each of the respective channel signals of the multi-channel signal
with a level set point corresponding to the frequency, and each of the different channel signals is
this level set point. The level of the above-mentioned angle modulated wave whose signal
containing at least this each other channel signal is f- signal is the time when each other channel
signal is also larger than this level set point. The carrier level / noise level ratio can be improved
because it is relatively enhanced to the level of the angle modulated wave, and any one channel
signal of the multi-channel channel signal is not higher than the above level set point. When the
relative modulation operation of the level of the above-mentioned angle modulation wave is
performed, and the above-mentioned remill control operation independent of the left and right
channels respectively, The noise t of the demodulation signal system can be optimally reduced,
and the noise of the demodulated signal of the angle modulation wave which is particularly easy
to be heard when the multi-channel record has a low output can be reduced when reproducing
multi-channel records. , Ff5N ratio can be improved, and so on.
4. Brief description of the drawings FIG. 1 is a block diagram showing one embodiment of the
uninvented system, FIG. 2 is a circuit diagram showing one embodiment of the main part of the
system of the present invention, FIG. 3 (A) (E) is a time chart for explaining the operation of the
second group, FIG. 4 shows the equalizer characteristic of one embodiment of the main part of
FIG. 2, FIG. 5 is an angle modulation of multichannel record It is a figure which shows the typical
characteristic of noise distribution of a wave demodulation signal. 3 ... signal processing circuit
(arithmetic circuit), 5 ... angle f adjuster, 6 ... angle modulated wave level control circuit, 10s11,
34i, 31 ... each channel signal input terminal, 1B, 1.7 · · · · · · equalizer circuit, 20. 2 '· · · buffer and
waveform shaper, 25. 32 · · · voltage 1111 111 amplifier, 211. 27 · · · 曳 modulation wave human
power insulator, 30. 34 ... the corner Bt strange - wave deca terminal. Patent applicant Nippon
Victor Co., Ltd. Attorney Attorney Ito Tada EndPage: 4
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