JPS5944818B2 - Crosstalk component cancellation circuit in angle modulated wave signal transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crosstalk component cancellation circuit in an angle-modulated wave signal transmission line, and the present invention relates to a crosstalk component canceling circuit in an angle-modulated wave signal transmission line, which eliminates angle-modulated wave signals of a desired channel among a plurality of angle-modulated wave signals modulated by different modulation signals. An object of the present invention is to provide a crosstalk component cancellation circuit capable of canceling crosstalk components from adjacent channels included in a wave signal and demodulating an angle-modulated wave signal of a desired channel with high fidelity.

As a plurality of angle-modulated wave signal transmission paths modulated by different modulation signals, there is, for example, a multi-channel difference signal transmission system that is recorded and reproduced on a multi-channel record.

In a multi-channel record, the multi-channel audio signal is made into a sum signal and a difference signal, and the difference signal is further angle-modulated, and the obtained angle-modulated wave signal is multiplexed with the sum signal of the direct wave to create one sound groove. recorded on both sides of the wall.
For this reason, in the recording and playback systems of multi-channel records, crosstalk tends to occur between the angle-modulated wave signals on both sound groove walls, and in this case, the angle of the angle-modulated wave signals changes, causing intermodulation distortion. arise. In the multiple angle modulated wave signal transmission paths as described above, if the angle modulated wave signal of the desired channel contains crosstalk components from adjacent channels, intermodulation distortion will occur as described above, and the detected output will be This causes distortion.

Therefore, in order to reduce this crosstalk component, a method such as controlling the level of the demodulated signal of the angle-modulated wave signal according to the envelope of the angle-modulated wave signal can be considered (for example, as described in Japanese Patent Publication No. 52-2595). invention).

However, in this way, after demodulation, it is represented in black. Above a
The signal KSB at the point is divided by resistors R4 and R5 and supplied to the rectifier circuit 6, where it is envelope-detected and supplied to one input terminal of the voltage comparator 8.

Similarly, the -KSB signal at point b is divided by resistors R6 and R7 and supplied to the rectifier circuit 7, where it is envelope-detected and supplied to the other input terminal of the voltage comparator 8. on the other hand,
The above voltage c is applied to the connection point d1 between resistors R4 and R5 and the resistor R6.
A predetermined division ratio is applied to the connection point of R7 and 7FL6e. ，?
It is divided by Tlnillll and added.

Therefore, the voltage Vd at point d is expressed by the following equation.

Similarly, the voltage e at point e is expressed by the following equation.

here, Then, becomes.

Therefore, by substituting equations (4) and (5) into equations (2) and (3), ▼ν11~K. Jl5-\↓′ノ▼νXU′.

When formula (1) is substituted into formulas (6) and (7) to eliminate Vc, the voltages Vd and Ve are expressed by the following formulas. The voltages Vd and Ve mentioned above are rectified by envelope detection circuits 6 and 7, and subjected to envelope detection and supplied to a voltage comparator 8.
Here, the levels are compared and a voltage is generated by amplifying the difference between these voltages, and is applied to the variable attenuator 5 as a control voltage for controlling the amount of attenuation L. Here, if there is crosstalk between a plurality of angle-modulated wave signals, the envelope of the composite signal of the angle-modulated wave signals and the crosstalk component changes according to the angular difference between the two modulated waves. Therefore, when comparing a signal with a small amount of crosstalk and a signal with a large amount of crosstalk, the larger the amount of crosstalk, the larger the amount of change in the envelope, and therefore the time constant circuit whose fall time is longer than its rise time. The output of a general envelope detection circuit such as Nos. 6 and 7 having a larger amount of crosstalk becomes a larger DC output.

The voltage comparator 8 compares a large part of the envelope of the signal Vd with the signal e.
When the level of the large part of the envelope of the signal d is higher than the level of the large part of the envelope of the signal Ve, the attenuation amount L of the variable attenuator 5 is reduced. When the level of the large part of the envelope of the signal d is lower than the level of the large part of the envelope of the signal e, the variable attenuator 5
A control voltage is outputted to cause the operation so that the amount of attenuation L becomes large.

That is, the signal Vd and the signal Ve are respectively the signal Vc
is the sum of the positive-phase and negative-phase crosstalk components, so if the signal Vc contains a large amount of positive-phase crosstalk components, the crosstalk component of the signal Vd increases, and the signal Ve's crosstalk component increases. The crosstalk component decreases, the level of the large part of the envelope of the signal d becomes higher than the large part of the envelope of the signal Ve, and more signals of the opposite phase are added to the point c, and, When the signal Vc contains a large amount of anti-phase crosstalk, the crosstalk of the signal d decreases, the crosstalk of the signal Ve increases, and a large part of the envelope of the signal e becomes the signal Vd. The level is higher than that of the large part of the envelope, and less signals of opposite phase are added to point c.

Therefore, the positive-phase crosstalk component of the signal c and the negative-phase crosstalk component act to be equal, and as a result, at the point when the levels of the large part of the envelope of the signal d become the same, The circuit operation becomes stable. As a result, the crosstalk component of the angle modulated wave signal at point c is canceled out and removed.

However, here, the time difference between the two signals between the time when the crosstalk component of the adjacent channel signal is mixed into the main channel signal and the time when the circuit for canceling this crosstalk component is activated is the difference between the two signals. It is not always constant due to differences, etc.

What is the difference between these times with respect to the wavelength λ of the O111 carrier of the angle modulated wave signal? When the relationship is λ(n-1, 2, A...), the time point at which crosstalk is added is
900 between both signals when trying to cancel crosstalk
As mentioned above, the crosstalk component cannot be canceled depending on the output signal of the amplifier 3 with a phase difference of 00 and the output signal of the phase inverter 4 with a phase difference of 180.

Therefore, the present invention provides the following circuit in the illustrated embodiment so that the crosstalk component can be canceled even in such a situation, and furthermore, even if the phase difference between the two points is arbitrary. That is, the output signal of the amplifier 3 is supplied to the 900 phase shifter 9,
After being phase-shifted by 90 signals, the signal is phase-inverted by a phase inverter 10, and a signal finally phase-shifted by 270 signals is taken out and supplied to a variable attenuator 11.

The output end of this variable attenuator 11 is connected to one end of a resistor Rl2 via a resistor R,3. The output end of the phase shifter 9 is connected to the output terminal 15 via resistors Rl4 and R,5 in series, and is connected to the other end of the resistor Rl2.
Further, the output terminal of the phase inverter 10 is connected to the output terminal 15 via resistors Rl6 and Rl7 in series. Resistance Rl
2 to Rl7 correspond to resistors R2 to R7, respectively. The output signal of the phase shifter 9 is divided by resistors Rl4 and Rl5,
And a resistor Rl divided by resistors R,4 and Rl5
The mixed signal is mixed with the signal at the connection point f between Rl2 and Rl3 and is supplied to the envelope detector 12.

On the other hand, the output signal of the phase inverter 10 is
The voltage is divided by the resistors Rl6 and Rl7, and the signal is mixed with the signal at the point f and sent to the envelope detector 1.
3. DC voltages having different levels depending on the envelope are supplied from the envelope detectors 12 and 13 to a voltage comparator 14, where the levels are compared and then supplied to the variable attenuator 11 as a control voltage. Like the voltage comparator 8, the voltage comparator 14 variably controls the amount of attenuation of the variable attenuator 11 so that the peak values of the envelopes of the input signals of the envelope detectors 12 and 13 or the changes thereof are equal to each other. do. In this case, the output of the phase shifter 9 is phase-shifted by 90 degrees, and the output of the phase inverter 10 is phase-shifted by 270 degrees, so if there are many 90 components of crosstalk in the signal at point f, The peak value of the input signal of the envelope detector 12 or the amount of change thereof increases, and the peak value of the input signal of the envelope detector 13 or the amount of change thereof decreases.

In addition, when there are many 270 components of crosstalk in the signal at point f, the peak value of the input signal to the envelope detector 13 or its variation increases, and the peak value or change thereof of the input signal to the envelope detector 13 increases. The amount of change will be smaller. As a result, the real component of crosstalk (component at 0 left or 180) is canceled by the circuit on the left half of the figure.
The angle-modulated wave signal at the point is output from the output terminal 15 after the imaginary component of crosstalk (component at 90 right or 270) is canceled by the circuit on the right half of the figure.

On the other hand, as mentioned above, the crosstalk component of the adjacent channel signal mixed into the main channel signal is
00, 18 for the adjacent channel signal SB coming into the
If you do not have a phase difference next to 0 or 90 or 270, but have another phase difference, for example, if there is a phase difference of 300, the COs3O component in the 0 field direction and the 90 direction The crosstalk component of the Sin3O-directed component is separated,
The COs3O direction component is caused by the circuit on the left half of the figure, and also by the Si
For the n3O direction component, the amount of crosstalk corresponding to each component is canceled by the circuit on the right half of the figure.

Therefore, even in such a case, the output terminal 15 outputs the main channel signal in which the crosstalk components from the adjacent channel signals have been canceled. In this way, what is the phase difference that occurs between the phase of the main channel signal and the adjacent channel signal at the time when the crosstalk component occurs and the phase of the main channel signal and the adjacent channel signal at the time when the crosstalk component is to be canceled? Even if it is degree, 0th place, 1st place
It can be decomposed into 800, 90, and 2700 vector components, and the circuit of the present invention can cancel the crosstalk components in these vectors. In addition, each voltage comparator 8, 14 in the above embodiment is simply 2
This circuit generates a voltage difference between inputs, and the signal supplied to the envelope detectors 6 and 7 is a mixture of a 0 direction signal and an angle-modulated wave signal, and is used for envelope detection. Vessel 1
Since the signals supplied to 2 and 13 are a mixture of the 900 direction signal and the angle modulated wave signal, the 900 direction signal and the 00 direction component of the crosstalk of the angle modulated wave signal are mixed.
The output level of each voltage comparator 8, 14 differs depending on the component in the 0 direction, and as a result, the output levels of the variable attenuators 5, 14 differ depending on the component in the 0 direction and the component in the 90 direction. 11 can be controlled.

In this embodiment, the phase of the output adjacent channel signal of the amplifier 3 is shifted by 900 degrees by the 90 degrees phase shifter 9, but the phase may be shifted by a certain angle of 90 degrees ± 45 degrees. However, it is possible to perform a cancellation operation using each decomposition vector for crosstalk components at arbitrary angles.

Further, the variable attenuators 5 and 11 are not limited to the above embodiments, but may be connected in series with the resistors R2 and Rl2, or in series with the resistors R2 and R3 and Rl2.
The same operation as above can be achieved by inserting two in each of R and R, for a total of four.

As described above, the crosstalk component canceling circuit in the angle-modulated wave signal transmission line according to the present invention inverts the phase of the first angle-modulated wave signal of the adjacent channel adjacent to the desired channel to produce the second angle-modulated wave signal. A modulated wave signal is obtained, a third angle modulated wave signal is obtained by shifting the phase by a predetermined angle, and the first and second angle modulated wave signals are outputted from the adjacent channel via the first level variable means. are mixed into the angle-modulated wave signals of the desired channels containing the crosstalk components, and this mixed signal is mixed with the first and second angle-modulated wave signals by a predetermined amount, respectively, to generate the fifth and sixth angle-modulated wave signals. A fourth angle-modulated wave signal, which is an angle-modulated wave signal and has a substantially opposite phase relationship with the third angle-modulated wave signal, is transmitted to the desired angle-modulated wave signal through the second level variable means. The signals obtained by mixing the angle modulated wave signals of the channels, respectively, are mixed into the third and fourth channels.
A predetermined amount of each angle modulated wave signal is mixed into the seventh and eighth angle modulated wave signals, and the detection output of the envelope of the fifth to eighth angle modulated wave signals is used to generate the first angle modulated wave signal. The signal level of at least one of the angle-modulated wave signals of the first to fourth angle-modulated wave signals is varied by the first or second level variable means, and the first signal is mixed with the angle-modulated wave signal of the desired channel. Since the fourth angle modulated wave signal is configured to be minimized, it has the following features.

1. Regardless of the phase difference between the crosstalk component from the adjacent channel contained in the angle-modulated wave signal of the desired channel and the first angle-modulated wave signal of this adjacent channel, the crosstalk component can be definitely canceled out.

2. By introducing a configuration in which the angle-modulated wave signal of the desired channel whose crosstalk component has been canceled is guided to the angle-modulated wave demodulation circuit to obtain a demodulated output, the crosstalk between the angle-modulated wave signals can be reduced. A demodulated output signal from which generated interference distortion is effectively removed can be obtained, and a high-fidelity demodulated signal can be obtained.

[Brief explanation of the drawing]

The figure is a circuit system diagram of an embodiment of the circuit of the present invention. 1... Angle modulated wave signal input terminal of desired channel, 2... Angle modulated wave signal input terminal of adjacent channel, 4, 10... Phase inverter, 5 ,1
1...variable attenuator, 6, 7, 12, 13...
...Envelope detector, 8,14...Voltage comparator.

Claims (1)

[Claims] 1. In a transmission path for a plurality of angle-modulated wave signals that are angle-modulated by different modulation signals, a first angle-modulated wave signal of an adjacent channel adjacent to the desired channel is phase-inverted to generate a second angle-modulated wave signal. At the same time as obtaining the signal, a third angle modulated wave signal is obtained by shifting the phase by a predetermined angle, and the first and second angle modulated wave signals are outputted from the adjacent channel through the first level variable means. The crosstalk component is mixed with the angle modulated wave signal of the desired channel, and the mixed signal is mixed by a predetermined amount with the first and second angle modulated wave signals, respectively, to form the fifth and sixth wave signals. As an angle modulated wave signal,
The third angle-modulated wave signal and the fourth angle-modulated wave signal having a substantially opposite phase relationship with this signal are converted into the angle-modulated wave signal of the desired channel via the second level variable means. The signals obtained by mixing the respective signals are mixed with the third and fourth angle-modulated wave signals by a predetermined amount to obtain seventh and eighth angle-modulated wave signals, and the fifth to eighth angle-modulated wave signals are Varying the signal level of at least one of the first to fourth angle-modulated wave signals by the first or second level varying means based on the detected output of the envelope of the angle-modulated wave signal, Crosstalk component cancellation in an angle modulated wave signal transmission path, characterized in that the number of the first to fourth angle modulated wave signals mixed with the angle modulated wave signal of the desired channel is minimized. circuit.