JPS5943854B2 - 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.

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

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 side walls.
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 produces 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. The present invention solves the above problems by canceling the crosstalk component before demodulating and detecting the angle modulated wave signal including the crosstalk component.Each embodiment of the present invention will be described below with reference to the drawings. do.

They are added to the connection point d and the connection point e between the resistors R6 and R7, respectively, in a predetermined division ratio of 9.

Therefore, the voltage V at point (d) is expressed by the following formula)
d.

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

DD here, Then, becomes.

Therefore, if we substitute equations (4) and (5) into equations (2) and (3), we get -゛2゛↑16W? Tomiji? ? God\: Ru.

The voltages Vd and Ve mentioned above are rectified by rectifier circuits 6 and r, and subjected to envelope detection and supplied to a voltage comparator 8, where the levels are compared and a voltage is generated by amplifying the voltage difference, and a variable attenuation is performed. It is applied to the device 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 rectifier circuit such as Nos. 6 and 7 having a larger amount of crosstalk becomes a larger DC output.

Here, when the voltage comparator 8 changes the attenuation amount L so that the peak value of the envelope of the signal Vd (5Ve becomes the same), the resistance ratio R4:R is used to improve the crosstalk component removal ratio. ,,R6:R, must be selected accurately,
Furthermore, the characteristics of the rectifier circuits 6 and 7 must also match well.

However, in general, these resistance ratios, characteristics, etc. often have slight errors. Further, the signals Vd and Ve are signals having a level of a certain amount of crosstalk with respect to the signal SA (for example, when looking at the signal Vd, △SB, but △=(1
-γ)(δ+αK-βKL)+γK is mixed, but it is very small with respect to the signal SA.If the losstalk amount △ is selected to be about 0.1, the amplitude modulation of the mixed signal (SA+△SB) will change to the modulation degree. This is converted to 10%, and the output voltage of the rectifier circuit 6 changes by only about 10% compared to A when there is no crosstalk (when only the signal S is present).

That is, the voltage comparator 8 receives signals V, . The voltage levels of O are compared and a signal corresponding to the level difference between both signals is output. In this example,
Since all outputs of the voltage comparator 8 are determined to be caused by crosstalk, if a voltage comparator 8 that operates normally is used, it is assumed that the signals Vd and VO have crosstalk with respect to the signal SA. Even if not included, if there are variations in the resistors R4 to R, and non-uniformity in the characteristics of the rectifier circuits 6 and 7, a difference in DC level will occur between the signals Vd and Ve. The voltage comparator 8 outputs an output according to this level difference, which has the drawback of causing the variable attenuator 5 to operate unnecessarily even though the signals D and Ve do not include crosstalk with respect to the signal SA. .

Therefore, in the present invention, the output of the voltage comparator 8 is always set to the signal V so that the DC level of each signal caused by the above-mentioned resistance variations etc. does not affect the operation of the variable resistor 5.
This is the difference voltage between the amount of crosstalk for the signal SA mixed in d and the amount of crosstalk for the signal SA mixed in the signal Ve. The comparator 8 is operated in accordance with alternating current changes in the envelopes of the signals D and Ve.

That is, the voltage comparator 8 variably controls the attenuation amount L of the variable attenuator 5 so that the alternating current variation (amplitude modulation degree) of the envelopes of the signals Vd and Ve are equal. As a result, the crosstalk component in the angle-modulated wave signal at point c is canceled, and only the main channel signal SA is taken out at the output terminal 9. In addition, at this time, even if an error component of each DC output voltage of the rectifier circuits 6 and 7 occurs due to resistance value error of the resistors R4 to R, or non-uniform rectification characteristics of the rectifier circuits 6 and 7, the above-mentioned The operation of the voltage comparator 8 allows stable cancellation of crosstalk components. The reason why malfunctions due to errors due to variations in resistance can be prevented by doing the above is because, as mentioned above, the amount of crosstalk is directly related to the amount of change in the envelope. By controlling the variable attenuator 5 only by the amount of change in the envelope (alternating current change amount), errors due to variations in resistance, etc. will no longer affect the correction amount.

Since the crosstalk component of the angle-modulated wave signal SA taken out from the output terminal 9 has been canceled and removed, no distortion occurs when it is demodulated by a demodulator (not shown), resulting in high fidelity. Detailed demodulation is performed.

FIG. 2 shows a circuit system diagram of a second embodiment of the circuit of the present invention.

In the figure, the same parts as in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted. In this embodiment, the detection of the change in the envelope described above is configured by cascading rectifier circuits 6 and 7, high-pass filters 10 and 11, and rectifier circuits 12 and 13. The output signals of the rectifier circuits 6 and 7 are supplied to high-pass filters 10 and 11, where the DC component is blocked from passing, and only the AC component of the amplitude modulation component generated depending on the amount of crosstalk is passed. This AC component is supplied to rectifier circuits 12 and 13, where it is converted into a DC voltage according to its level and supplied to a voltage comparator 14. The voltage comparator 14 adjusts the attenuation amount L of the variable attenuator 5 so that the input DC levels are equal to each other.
variably controlled. The voltage comparator 14 is supplied with the output voltage of the rectifier circuit 12 and the output voltage of the rectifier circuit 13, compares these two input voltages, and outputs a voltage according to the difference voltage, and the variable attenuator 5 It has a variable resistance element whose resistance value changes depending on this voltage, and for example, when the output DC voltage of the rectifier circuit 12 is at a higher level than that of the rectifier circuit 13, the attenuation amount L is set to be small. , variable attenuator 5
Voltage comparator 1 converts the control voltage that operates the variable resistance element, etc.
4 generates and outputs. Here, the output of the rectifier circuit 12 is a DC voltage at a level corresponding to the AC component of the amplitude modulation component of the signal V, and that of the rectifier circuit 13 is a DC voltage at a level corresponding to the AC component of the amplitude modulation component of the signal Vd. It is.

Therefore, the fact that the output DC voltage of the rectifier circuit 12 is higher than that of the rectifier circuit 13 means that the signal V. This means that there are many positive-phase components in the crosstalk components. Therefore, by controlling the attenuation amount L of the variable attenuator 5 to be small and adding a large number of signals of the opposite phase to the voltage at point c, the signal V
By relatively increasing the alternating current component of the amplitude modulation component of d, the signal V
By making the alternating current component of the amplitude modulation component of d equal to that of the signal Ve, the input level of the comparator 14 is made equal. The alternating current component of the amplitude modulation component of the signal Vd and the signal Ve
is equal to that of (1go) (δ+α+
Absolute value of βKL) + γK and (1-γ) (δ{-βKL)
This means that the absolute value of -γK is equal.

(Here, (1-γ)SB is constant, so there is no need to consider it.) In order for this to hold true, (1-γ)(δhypnosis-βKL)=0, that is, it must be satisfied.

This gives VO=SA in equation (1).

Therefore, in this embodiment as well, as in the first embodiment, the main channel signal with the crosstalk component canceled can be stably extracted from the output terminal 9 without being affected by errors in the circuit elements.

In each of the above embodiments, the output angle modulated wave signal of the phase inverter 4 is variably attenuated, but the present invention is not limited to this, and the variable attenuation circuit 5 is connected to a resistor R.
A similar operation can be achieved by inserting two resistors in series with R2 or in each of resistors R and R3. As described above, the crosstoter component cancellation circuit in the angle-modulated wave signal transmission line according to the present invention is obtained by inverting the phase of this signal and the first angle-modulated wave signal of the adjacent channel adjacent to the desired channel. The second angle modulated wave signal is applied to the adjacent channel through the level variable means. A predetermined amount of this mixed signal is mixed with the first and second angle modulated wave signals, respectively, and the third and second angle modulated wave signals are mixed with the angle modulated wave signals of the desired channels. 4 angle modulated wave signals are obtained, and the angle modulated wave signals of the first and second angle modulated wave signals are adjusted so that the changes in the envelopes of the third and fourth angle modulated wave signals are equal to each other. Since the level of at least one of the signals is varied by the level variable means and mixed with the angle modulated wave signal of the desired channel and output, the output signal is free from crosstalk components from the adjacent channels. The angle modulated wave signal of the desired channel can be canceled, and even if there is an error in the circuit elements, the change in the envelope can be detected, so the crosstalk component cancellation characteristics described above can be improved. By configuring the output signal to be kept stable and guiding this output signal to the angle modulated wave signal demodulation circuit to obtain the demodulated output, interference distortion caused by crosstalk of each angle modulated wave signal can be suppressed. This method has the advantage of being able to obtain a demodulated output signal that is effectively removed and a demodulated signal with high fidelity.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams of first and second embodiments of the circuit of the present invention, respectively. 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, 12, 13... Rectifier circuit, 8, 14... Voltage comparator, 10, 11...
...High frequency filter.

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 changes in 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.