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JPS515726

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DESCRIPTION JPS515726
■ Transmission system of stereophonic sound signal by time division multiplex system O
Japanese Patent Application No. Sho 45-71057 [Phase] Application Akira 45 (1970) August 13 0
inventor Maruyama Fumio Yokohama city 12 JVC in Moriyacho, Kana district, Yokohama City
Uchido Yamazaki Masami. Same place same place Haruhi Koharu same place 0 applicant Japan
Victor Co., Ltd. Yokohama 12 Kanagawa [Konawa-ku, Moriya-cho 3]
BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are waveform diagrams for explaining a
large amount of signals in the conventional time division multiplex system, FIG. 3 is a waveform
diagram for explaining a multiplex signal in the system of the present invention, and FIG. FIG. 16
is a block diagram of a three-dimensional sound signal transmission method of FIG.
Detailed Description of the Invention As transmission systems of three-dimensional sound
signals, various types of transmission systems have conventionally been proposed, and so-called
45-45 system is used for a single grooved disk record, and a magnetic tape file reproduction
apparatus is also used. It is well known that the multi-track simultaneous recording and
reproducing system and the carrier wave suppression AM-FM system for the broadcasting
system are put to practical use. The present invention makes it possible to simplify the
configuration of the reproduction system by using a special time division multiplex signal in the
transmission system of the stereophonic sound signal, and to obtain superior performance at
lower cost than in the conventional system. The present invention provides a three-dimensional
sound signal transmission method. Conventionally, in time division multiplexing technology, as
shown in FIG. 1 or FIG. 2, pulses of each channel are arranged on the basis of a synchronization
signal pulse in [111111] so as to be mainly arranged in time axis. FIG. 1 shows a model in which
the pulses P1... = P2... Of each channel amplitude-modulated by different signals S1> 82 are
arranged on the time axis with reference to the synchronization signal pulse Ps. FIG. 2 shows
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pulses P1... P2... Of each channel amplitude-modulated by different signals S1 and S2 and
synchronization signal pulses Ps transmitted in parallel in channels of different systems. It
models and shows the state arranged on the time axis on the basis of. Among the abovedescribed conventional methods, in the case of a time division multiplexed signal having a pulse
arrangement as illustrated in FIG. 1, it is necessary for transmission of a time division
multiplexed signal with pulse width γ and pulse repetition period T. In the case of a time
division multiplexed signal having a pulse arrangement as illustrated in FIG. 2, another channel
for transmission of the synchronization signal pulse Ps is used. There was a drawback that it
needed extra. By the way, since the operable frequency range of the cutting machine head used
for cutting the sound groove of the disc record, the magnetic head used for the magnetic
recording of the magnetic tape-, etc. is relatively narrow, Time-division multiplexing of
stereophonic sound signals by the conventional method makes it possible to satisfactorily record
stereophonic sound signals on a disk record or magnetic tape and requires a wide frequency
band communication path for the transmission. It will be. In the present invention, first, the pulse
widths of the pulses of the two pulse trains separately modulated by two signals of the
stereophonic signal are made different from each other to eliminate the use of synchronization
signal pulses, thereby solving the above problems. .
In FIG. 3, the pulse train pulse modulated by the signal PL of one channel [111111] EndPage: 1
Bt, and Pr is the pulse train pulse modulated by the signal Sr of the other channel, and the
example shown in FIG. The pulse width T1 of the pulse Pt and the pulse width .gamma.2 of the
pulse Pr have a relation such as .tau.1> .tau.2, but in the practice, the pulse widths of the both
may be in a relation such as .gamma.1 <.tau.2. The pulse width τ1 of the pulse PL of the pulse pt
and the pulse width τ2 of the pulse Pr have a difference such that the two pulses can be
distinguished due to the difference in pulse width at the time of demodulation. FIG. 4 is a block
diagram of the stereophonic signal transmission system of the present invention, in which A is a
block on the recording or transmitting side, B is a transmitting means such as a recording
medium or transmission path, and C is a reproducing or receiving side. The block of, respectively.
Two signals St and Sr are supplied from the signal source (not shown) to the input terminal 1.2 to
the recording or transmitting side block A. The two input signals St and Sr applied to the input
terminals 1 and 2 are respectively amplified by the amplifiers 3 and 5, then subjected to a
sampling operation at the gates 4 and 6 and added by the adder 7 to be time division multiplexed
signal It is recorded on the recording medium B by a cutting machine or a magnetic head (not
shown), or it is sent to the transmission path B by modulating the carrier wave in a transmitter
(not shown). The gate pulse (Sampling Harus) PJ applied to the gates 4 and 6 described above! /
−Pr is generated by the 嘱 oscillator 8 and the shaper 23, and each has a constant repetition
period T and mutually different pulse widths τ1. The two gate pulses PL and Pr have pulse
widths τ1 and τ2 that are generated at time positions including τ2 and not mutually
overlapping in time. The relationship between τ 2 and the pulse repetition period T 1 and the
impact coefficient is expressed by □ 1 の 1, and the pulse trains of the two gate T-pulses Pt and
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Pr have an antiphase relationship with each other. It is. In addition, when the human power
signals Bt and Sr occupy the frequency band of 0 to fIW 1111 1 1 1 kHz, respectively, in order to
faithfully reproduce the original signal, it is necessary to satisfy the respective pulse relationships
described above. It is a matter of course from. The time-division multiplexed signal sent out from
block A has a chi signal by a pulse train consisting of a pulse pt consisting of pulses pt with a
pulse width of τ1 and a repetition period of T with a pulse width of amplitude modulated by a
signal Bt and a pulse width with amplitude □ modulated by a signal Sr. It is composed of a pulse
train consisting of a pulse train consisting of HA / Pr with a repetition period of T and a
repetition period of T, including a synchronization signal pulse used to separate the above two
series of pulse trains. Not.
Next, as described above, the configuration of the block C on the reproduction side or the
reception side in which each channel signal Ch1 ° C. 50 is correctly separated and reproduced
from the time division multiplex signal having no synchronization signal pulse will be described.
Do. The time division multiplexed signal applied to block C is amplified by amplifier 22 and then
applied to gou 9.10 and sampling pulse generation circuit G. The sampling pulse generation
circuit G is, in the illustrated embodiment, a high-pass filter 11, an amplifier 12 having an
automatic gain control function, a limiter 13, a waveform shaping circuit 14, a self-oscillation
oscillator 15, a waveform shaping circuit 16, a comparator 17, the phase converter 18, the
waveform shaping circuit 19 and the like, and the operation is as follows. The respective channel
signals Chi and C50 of the time division multiplexed signal given to the block C pass through the
high-pass filter 11 so that the alternating current of each channel signal Ch2 ° C. 50 (the time
position of the boundary division of each channel signal ) Is extracted, then the extracted pulse is
amplified by the amplifier 12 and then cut to a constant amplitude by the limiter 13 and given to
the waveform shaping circuit 14. The waveform shaping circuit 14 has pulse discrimination
means comprising, for example, a time constant circuit or the like for identifying a pulse interval
of a given pulse train, and the time of the boundary of each channel signal due to the difference
in pulse width of each channel signal ChLC50. By identifying the positions becoming wider and
narrower alternately, for example, a pulse is generated only in response to a pulse when the
interval [1111111EndPage: 2 interval becomes narrower]. The waveform shaping circuit 14
causes the pulse PL of one channel signal Ch1 (only one of the two channel signals ChltCh2 to be
extracted from the waveform shaping circuit 14). In the following description, the pulse shaping
circuit 14 is described as a pulse PL having a width of .tau.1 can be obtained), and the phase of
the oscillation wave of the self-oscillation oscillator 15 is controlled by this pulse PL. The output
pulse PL of the shaping circuit 14 is also applied to the comparator 17 as its comparison wave.
The output wave of the self-oscillation oscillator 15 is shaped by the waveform shaping circuit
16 into a pulse pt having a pulse width of τ1 and supplied to the phase converter 18 and also as
a reference wave to the comparator 17. The output of phase converter 18 is applied to waveform
shaper 19. The waveform shaper 19 generates a pulse PL having the same phase as the rightturned pulse Pt and a pulse Pr having the opposite phase thereto.
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The pulse PL which is one of the outputs of the waveform shaper 19 is applied to the gate 9 and
is used to extract one channel signal Dhl from the time division multiplexed signal. The other
pulse Pr of the output of the waveform shaper 19 is applied to the gate 10 and used to extract
the other channel signal Ch2 from the time division multiplexed signal. The gate width of each
gate pulse applied to the above-mentioned game 9.10 is the pulse width τ1 of each channel
signal ChLCh2 described above. If the width is narrower than τ2, a signal with less distortion
can be extracted. When the channel signals ChLCh2 of the time division multiplexed signal
supplied to the block C have different amplitudes from each other, the output of the high-pass
filter 11 in the sampling pulse generation circuit G is the channel signal Chi, Since the signal at
the boundary position of Ch2 is clearly output, in this state, the correct pulse PL is applied as a
comparison wave from the waveform shaping circuit 14 to the comparator 17, and to the
comparator 17, the waveform shaping circuit 16 is correct. Since the pulse Pt is given as a
reference wave, no error signal is sent out from the comparator 17, and the time division
multiplexed signal given to the block C is gated by one of the chan W-*-*-r. −−−−−− + 1
channel signal Ch1 is correctly extracted, and gate 10 correctly extracts the other channel signal
Ch2 and then Original signal St. by being integrated by an integrator circuit 20 ° 21 Sr is
regenerated. However, when the peak values of the channel signals Chi and Ch2 of the timedivision multiplexed signal supplied to the block C are extremely close to each other, the output
of the high-pass filter 11 in the sampling pulse generation circuit G is Since the signal at the
boundary position of each channel signal Ch1 and Ch'2 appears very little, the comparison wave
supplied from the waveform shaping circuit 14 to the comparator 17 and the reference wave
supplied from the waveform shaping circuit 16 to the comparator 17 The difference is that the
comparator 17 sends out an error signal. The above error signal causes the amplifier 12 having
an automatic gain control function to be changed to an operation state in which the gain is
improved, and controls so that the correct pulse PL appears at the output of the waveform
shaping circuit 14. The error signal obtained from the comparator 17 is also applied to the phase
converter 18, and the phase of the pulse train output from the phase converter 18 to the
waveform shaping circuit 19 is maintained during the period when the error signal is output.
Reverse.
In the phase converter 18, the application of the pulse PL for oscillation phase regulation to be
given to the prescribed time position from the waveform shaper 14 is not performed for a long
time with respect to the self-oscillation oscillator 15 (each channel signal Chi). In the case where
the peak value of Ch2 is the same for a long time) and the oscillation wave of the self-oscillation
oscillator 15 gradually deviates from the normal phase during that time, When the normal pulse
Pt starts to be applied, the phase relationship between the normal pulse Pt and the oscillation
wave of the self-excitation oscillator 15 completely disappears, and the phase difference is a
value of ± 180 ° and 180 °. Even with exactly the same probability. Therefore, when
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considering the case where the phase difference between the two is close to 180 °, the case
close to O °, and the case close to 90 °, the values are first close to 180 °. In some cases, it
takes a long time for the oscillation wave of the self-excited oscillator 15 to be synchronized with
the normal pulse PL, and the oscillation wave is in antiphase with the normal pulse PL until
synchronization. If [1111111 EndPage: 3] is used as a gate pulse, the left and right signals are
reversed. Therefore, if the phase is converted by the phase converter 18 and used as a gate pulse
until synchronization is achieved (that is, while an error signal is present), right and left signal
powers are separated correctly even when synchronization is not achieved. The gate pulse train
of V.sup.2 is given quickly. Next, when the normal pulse PL is applied when the phase difference
is close to Oo, the self-excited oscillator 15 is synchronized immediately, and a normal gate pulse
train is applied to speed and force. Further, when the phase difference is close to 90 °, even if
the phase difference is reversed, the phase difference is close to 90 ° and substantially no
influence is caused by the phase reverse. When the phase of the pulse train is reversed during
the period when the error signal is output by the phase converter 15 in this manner, the phase of
the oscillation wave of the normal pulse PL and the oscillation wave of the self-excitation
oscillator 15 largely deviates, It operates effectively to quickly supply a regular gate pulse train
to each gate 9, 10, and does not adversely affect other cases. If the peak values of the channel
signals Chi and Ch2 of the stereophonic signal from the time division multiplexed signal supplied
to the block C are identical over a long period of time, a so-called monaural acoustic signal is
recorded or transmitted by each channel. Since the self-oscillation oscillator 15 does not apply
the pulse Pt for phase regulation to the self-oscillation oscillator 15, the gate 9 ° 10 controls
each channel signal under the control of the free oscillation wave in the self-oscillation oscillator
15. Even if it operates in a time position unrelated to the time position of Chi, (J2, the original
signal is faithfully reproduced.
Therefore, in block C, when the respective channel signals Chi and Ch2 of the respective channel
signals Chi and Ch2 constituting the time division multiplex signal are different from each other
in peak value, the respective channel signals Chi and Ch2 and Is sufficient to be sampled by the
respective predetermined game) 9.10, and it is sufficient that the random sampling (gating of
each gate under control of the free oscillation wave of the self-excited oscillator 15 over a long
period of time). The operation does not impair the reproduction of the stereophonic sound signal
in the case where there is no difference between the wave heights of the respective channel
signals Chi and Ch2. Then, the configuration of sampling pulse generation circuit G as described
above is performed in advance with respect to each game) 9.10 in the case where there is a
difference in peak value between each channel signal Chi and Ch2 constituting the time division
multiplexed signal. By applying a predetermined gate pulse train, synchronization is
automatically restored, and always operates so that an original signal can be obtained as an
output of the integrating circuits 20 and 21. As is apparent from the detailed description given
above, in the present invention, the pulse itself for carrying a stereophonic signal by making the
stereophonic signal into a time-division multiplexed signal by two series of pulse trains having
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different pulse widths. To make it possible to record and transmit stereophonic sound signals
within 5 narrow frequency bands, and to identify the pulse width of the pulse train that carries
each channel signal on the playback side. Since the original signal is reproduced by switching the
pulse train by providing means, the channel signals are always reproduced correctly, the levels of
the channel signals become equal, and the discrimination power temporarily decreases. The
fidelity of the reproduction of the original signal is not affected, and if the discrimination is
restored again, each channel signal can be reproduced correctly. Than is. Further, in the present
invention, a comparator is provided for comparing the output pulse of the self-excited oscillator
(synchronous oscillator) phase-locked by one of the detected pulse trains and this one pulse
train, and the error signal output of this comparator Since the amplification degree of the means
for detecting and amplifying one pulse train is increased and the output pulse of the synchronous
oscillator is inverted in polarity, for example, the level of each channel signal is close and one
pulse train is When the detection output from the means for detecting and amplifying is lowered
and the synchronization of the synchronous oscillator is lost, etc., the amplification degree of the
detecting and amplifying means is increased, and the detection output is increased. When the
levels of each channel are different for a long time and then the levels of each channel become
different again An effect such as the state of the channel signal separation is shortened the time
to return successfully.
[1111111EndPage: 4
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