JPS5943853B2 - 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 system and playback system of multi-channel records, crosstalk tends to occur between the angle-modulated wave signals on both side groove walls, and in this case, the angle of the angle-modulated wave signals changes, causing intermodulation distortion. . 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, with this method of reducing crosstalk components after demodulation, it is not easy to completely remove crosstalk components. In the present invention, before demodulating and detecting the angle modulated wave signal including the crosstalk component, the crosstalk component is detected and supplied to the other input terminal of the voltage comparator 8.

On the other hand, the above voltage V. is a predetermined division ratio, π, at the connection point d between resistors R4 and R, and the connection point e between resistors R6 and R7, respectively.
It is divided and added with ノ (he) [. Therefore, the voltage at point d is Vd.

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

here, Then, becomes.

Therefore, by substituting equations (4) and (5) into equations (2) and (3), the following is obtained.

Substitute equation (1) into equations (6) and (7), respectively. When the above voltages Vd and Ve are erased, the voltages Vd and Ve are expressed by the following equations. The above voltage Vd, 6 is rectified by rectifier circuits 6, 7, and
The envelope is detected and supplied to the voltage comparator 8, where the levels are compared and a voltage is generated by amplifying the voltage difference.
It 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 fall time is longer than the rise time. It has a time constant circuit 6,7
The output of a general rectifier circuit such as the one with a larger amount of crosstalk becomes a larger DC output.

A voltage comparator 8 compares the peak value of the envelope of the signal Vd with the signal V.

The level of the peak value of the envelope of the signal Vd is compared with the peak value of the envelope of the signal Vd. When the level of the peak value of the envelope of
The level of the peak value of the envelope is the signal. When the level of the peak value of the envelope is smaller than the level of the peak value of the envelope, a control voltage is output that causes the variable attenuator 5 to operate so that the attenuation amount L becomes large.
That is, signal Vd and signal V.

are the signal V, respectively. Since it is the sum of the positive phase and negative phase crosstalk, the signal V. If there is a large amount of positive-phase crosstalk in the signal Vd, the crosstalk in the signal Vd will increase. The crosstalk component decreases, the peak value of the envelope of the signal Vd becomes more level than the peak value of the envelope of the signal Ve, and more signals of the opposite phase are added to point c, and signal. If the signal Vd contains a large amount of negative phase crosstalk, the crosstalk of the signal Vd decreases. The crosstalk of the signal increases. The peak value of the envelope of signal Vd has a higher level than the peak value of the envelope of signal Vd, and less of the signal of the opposite phase is added to point c. Therefore, the signal V. The positive phase crosstalk and negative phase crosstalk of the signal Vd
The circuit operation becomes stable when the peak values of the envelopes become the same. Therefore, the conditions under which the peak values of the envelopes of equations (8) and (9) are the same will be explained.

SA and SB are angle modulated wave signals, and equation (8) and (
In equation 9), the coefficient of SA is equal to (1-γ), so let us consider the coefficient of SB. The conditions for the coefficients of this signal SB to be equal in both equations 8 and 9 are as follows. (
10) When the signs in the absolute values of the expressions are equal to each other, γK
=0 is the answer, but this answer is not relevant to the present invention in which L is varied. Therefore, if we solve equation (10) for the case where the signs in the absolute values are mutually opposite, we get r&, (111, - V
暉 w●― 〜↓
- becomes. In the present invention in which L is varied, (11)
Regardless of the equation, equation (12) is the answer in the present invention. That is, the variable attenuator 6 has an attenuation amount L of (1
2) It will be controlled as follows.

The value of VO at this time is obtained by substituting equation (13) into equation (1). Therefore, as is clear from equation (14), by controlling the ζ attenuation amount L to the value shown in equation (13),
In other words, by controlling so that the peak values of the envelopes of the signals Vd and Ve are equal, the signal SA with the crosstalk component δS3 canceled is led to the output terminal 9.

Therefore, by guiding the angle-modulated wave signal taken out from the output terminal 9 to a demodulator (not shown), high-fidelity demodulation can be performed. Note that in the present invention, the variable attenuation circuit 5 is connected to the resistor R2.
A similar operation can be achieved by inserting two resistors in series with each other or in each of resistors R2 and R3.

As described above, the crosstalk component canceling circuit in the angle-modulated wave signal transmission line according to the present invention is provided in the transmission line 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 and a second angle modulated wave signal obtained by phase inverting the first angle modulated wave signal are outputted from the adjacent channel via a level variable means. are mixed into the angle-modulated wave signals of the desired channels containing the crosstalk components, and the mixed signals are mixed by predetermined amounts into the first and second angle-modulated wave signals, respectively, to generate the third and fourth angle-modulated wave signals. obtain the angle-modulated wave signal, and set the first angle-modulated wave signal so that the peak values of the envelopes of the third and fourth angle-modulated wave signals are respectively equal.
The level of at least one of the second angle-modulated wave signals is varied by the level variable means and mixed with the angle-modulated wave signal of the desired channel and output. Regardless of whether the crosstalk component from the adjacent channel contained in the angle modulated wave signal is in positive phase or reverse phase, correction is automatically performed correspondingly to this, and the output signal is transferred from the adjacent channel. It is possible to obtain an angle-modulated wave signal of a desired channel in which the crosstalk component of This method has the advantage of being able to obtain a demodulated output signal in which interference distortion caused by crosstalk between the angle-modulated wave signals is effectively removed, and a demodulated signal with high fidelity can be obtained.

[Brief explanation of the drawing]

The figure is a circuit system diagram of an embodiment of a crosstalk component canceling circuit in an angle-modulated wave signal transmission line according to the present invention. 1...Angle modulated wave signal input terminal of desired channel, 2...Angle modulated wave signal input terminal of adjacent channel, 4...Phase inverter, 5... ...
・Variable attenuator, 6, 7... Rectifier circuit, 8...
...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, the first angle-modulated wave signal of the adjacent channel adjacent to the desired channel and the first angle-modulated wave signal are phase-shifted. The second angle modulated wave signal obtained by inversion is mixed with the angle modulated wave signal of the desired channel containing the crosstalk component from the adjacent channel through a level variable means, and this mixed signal is The first
and the second angle modulated wave signal by a predetermined amount to obtain third and fourth angle modulated wave signals;
The level of at least one of the first and second angle-modulated wave signals is varied by the level varying means so that the peak values of the envelopes of the angle-modulated wave signals are equal to each other. 1. A crosstalk component cancellation circuit in an angle modulated wave signal transmission path, characterized in that it is configured to be mixed with the angle modulated wave signal of the desired channel and output.