JP2850900B2 - Cross polarization interference canceller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a demodulation unit of digital microwave communication using a multilevel quadrature amplitude modulation system, and performs radio transmission of both polarizations using two orthogonal polarizations having the same frequency. In particular, the present invention relates to a cross polarization interference elimination device that eliminates cross polarization interference, and more particularly to a reset device for a cross polarization interference elimination circuit.

[0002]

2. Description of the Related Art A cross polarization interference canceling apparatus is an apparatus for operating a cross polarization interference canceling circuit based on a received signal on a different polarization side to remove interference. However, if the input signal is interrupted, if the unvariable head signal is input, or if the line quality of the received signal on the different polarization side is degraded, normal interference cancellation will not be performed and the self-polarization will be impaired. In these cases, it is necessary to immediately stop the cross polarization interference canceling function. As a first known example of such a cross polarization interference elimination device, a cross polarization interference elimination device disclosed in Japanese Patent Application Laid-Open No. 3-82236 is shown in FIG.
Shown in In this cross-polarized interference canceller, the self-polarized wave reception signal S1 is demodulated by a demodulator 401 and converted into a digital signal by an A / D converter 403. Similarly, the different polarization side received signal S2 is converted into a demodulated digital signal by the demodulator 402 and the A / D converter 404. Then, based on the demodulated signal on the different polarization side, the cross polarization interference remover outputs a signal S3 from which the cross polarization interference in the digital signal on the own polarization side has been removed. The cross polarization interference canceller includes a subtractor 405, a transversal filter 406, and a tap coefficient controller 407.
It consists of.

As a configuration for stopping the interference cancellation function in the cross polarization interference canceller, the state of the input signal of the demodulator with respect to the received signal on the different polarization side is monitored, and the input or signal is “cut” or “disconnected”. When the signal is “unmodulated signal”, the first
State detector 408 that outputs a reset activation signal
And receiving the demodulated signal on the different polarization side and monitoring the line quality,
A line quality detector 409 that outputs a second reset activation signal when the line quality is equal to or less than a predetermined value is provided. Further, the input state detector 408 and the line quality detector 409
Input the first and second reset activation signals from the
Each of the tap coefficients of the transversal filter 406 in the tap coefficient controller 407 is initialized in accordance with the reset activation signal input in any of the second places, and the reset state is maintained. If neither reset activation signal is input, a reset control circuit 410 is provided to release the reset state and return each tap coefficient of the transversal filter to adaptive control.

Therefore, according to this configuration, when a fault occurs on the different polarization side and the input signal is interrupted, or when a non-variable head signal is input, or when the reception signal on the different polarization side is When the line quality is degraded, the cross-polarization interference cancellation function is immediately stopped (reset) by operating the cross-polarization interference cancellation function using the differently polarized signals having the respective faults. Also, regarding the return from the reset state, when the first and second reset activation signals are not input together, the reset is performed so that the cross polarization interference removal function is operated again when the different polarization signal is in a normal state. Release the state.

As a second known example provided with the same technology, Japanese Patent Application Laid-Open No. 2-82831 proposes an apparatus shown in FIG. In FIG.
02 is an antenna, 503 and 504 are cross polarization interference compensators, 505 and 506 are adders, 507 and 508 are demodulators, and 509 and 510 are reset circuits. This device is characterized by including a reset circuit based on the second reset activation signal in the first known example described above, and when the line quality of the received signal on the different polarization side is deteriorated, The cross-polarization interference elimination function is stopped so that the cross-polarization interference elimination function is operated by the wave signal and does not disturb the self-polarization signal.

[0006]

In such a device having the conventional reset function, when the interference between the cross polarizations of the polarizations orthogonal to each other is large, out-of-synchronization occurs or the synchronization pull-in operation cannot be performed. Problem may occur. The reason will be described. FIG. 4 is a diagram showing a D / U ratio (a level ratio between a main wave and an interference wave) of polarizations orthogonal to each other and a synchronization pull-in range of each polarization reception signal with respect to the ratio. Polarizations orthogonal to each other are represented as V polarization and H polarization, respectively. In FIG. 4, points a and b are synchronization pull-in or out-of-synchronization points when the cross polarization interference cancellation function of V and H polarizations orthogonal to each other is stopped (reset).
A point J indicates a pull-in or out-of-synchronization point when the cross polarization interference canceling function of the V and H polarizations is operating and the reset state is not established.

First, in FIG. 4 (A), the region where both the V and H polarizations can be pulled in and not out of synchronization when the cross polarization interference canceling function is operated and the reset state does not occur is (c). And (d) in the hatched area,
It is considered that only the V polarization can be pulled in synchronously in the hatched area (A), and that only the H polarized light can be pulled in synchronously in the hatched area (A). However, in the cross polarization interference canceller of the first known example, the cross polarization interference amount of the V and H polarizations is larger than the synchronization pull-in point at the time of reset, and the cross polarization interference of one of the polarizations. Consider a case where the quantity is restored (improved) again after the quantity has deteriorated from the synchronization pull-in / out point at the time of operation of the cross polarization interference canceller. When the cross polarization interference amount of the V and H polarizations is at the point (1) in FIG. 4A, the input signal on the H polarization side is “cut” by the cross polarization interference canceller of the first known example. Alternatively, since it is not in any state of “unmodulated signal”, the first reset activation signal for V is not output. Also, H
Since the signal quality of the received signal on the polarization side is not degraded when the cross-polarization interference removal function is operated, the second reset signal is not activated.

Next, the cross polarization interference amount of V and H polarizations is shown in FIG.
(A) Let us consider a case where the transition to the point (2) occurs. Since the H polarization is in a state where the quality is degraded due to the cross polarization interference that cannot be synchronized, the second reset activation signal for the V polarization is output. Therefore, the V-polarized cross polarization interference canceller is reset. Due to this reset action, cross polarization interference exceeding the synchronization pull-in / out point at the time of resetting is present at the input of the V polarization, so that the signal quality is degraded without being eliminated and the V polarization is desynchronized. Also,
When the signal quality on the V polarization side is degraded, a second reset activation signal is output from the V polarization quality monitor to reset the H polarization cross polarization interference canceller. Even if the cross-polarization interference on the H-polarization side is improved from this state to the state of (1) in FIG. 4 (A), since the cross-polarization interference canceller for the H-polarization has been reset, synchronization is not achieved. Unless the pull-in is performed and the cross-polarization interference on the H-polarization side does not recover to the point (5) in the hatched area (d), the cross-polarization interference cancellers on both the V and H must perform synchronization pull-in. Can not.

Since the above description is the same when the V and H polarizations are replaced, the synchronization pull-in range when the V and H reception signals go out of synchronization from the synchronization pull-in state is shown in FIG. The hatched area in FIG. 4C is the hatched area in <B>, and the synchronization pull-in range when the cutting edge goes out of synchronization to the synchronization pull-in.

As described above, the synchronization pull-in range of the received signals of V and H when the V and H cross polarization interference cancellers are not reset, that is, the synchronization pull-in range when the synchronization is lost from the lock-in state. As a problem, in the hatched areas (A) and (A) of FIG. 4A, there arises a problem that either the V or H polarization is degraded from the state in which synchronization is pulled. In addition, there is a question that the synchronization pull-in range from the out-of-synchronization state to the synchronization pull-in is greatly deteriorated as compared with the hatched areas (c) and (d) in FIG. Also, in the second known example, since the first reset activation signal is not output in the first known example, the same problem as described above exists.

An object of the present invention is to perform synchronization pull-in with the maximum capability of the cross polarization interference canceller even when the cross polarization interference is large when the cross polarization interference canceller is used, and If the signal quality of the hetero-polarization deteriorates after synchronization pull-in for other reasons, reset the cross-polarization interference canceller of the self-polarization and use the degraded hetero-polarization signal to reduce the signal quality of the self-polarization. An object of the present invention is to provide a cross-polarized interference canceller capable of preventing the interference.

[0012]

SUMMARY OF THE INVENTION A cross-polarization interference canceller according to the present invention monitors the state of an input signal on the side of different polarization and, when the input signal is disconnected or unmodulated, removes the self-polarized signal. An input state detector for outputting a first reset activation signal by
Monitoring the line quality on the different polarization side, and outputting a second reset activation signal to the own polarization side when the line quality is equal to or less than a predetermined value;
A line quality detector that outputs a fourth reset activation signal on the different polarization side, and a third signal on the own polarization side when the amount of interference is large based on the amount of cross polarization interference on the own polarization side. A cross-polarization interference detector for outputting a reset release signal, and a self-polarized cross-polarization interference remover that receives the first, second, and fourth reset activation signals and the third reset release signal And a reset circuit for controlling the reset state of

Here, the cross polarization interference canceller is constituted by a transversal filter, and the cross polarization interference amount detector detects the cross polarization interference amount from the output of the transversal filter and cancels the third reset. It is configured to output a signal. That is, the cross-polarization interference amount detector compares the cross-polarization interference amount that leads to synchronization pull-in or out-of-synchronization when the cross-polarization interference removal function is stopped with the input cross-polarization interference amount, and when the interference amount is large. To output the third reset release signal. In addition, the reset circuit is configured to perform a third reset activation signal with respect to the first and second reset activation signals.
The reset reset signal is released from the reset state, and the fourth reset activation signal is set to the intermittent reset state in which the transversal filter is reset and the adaptive equalization operation is repeatedly performed. It is configured to perform.

In the cross polarization interference canceling apparatus according to the present invention, the input state detector outputs the first reset activation signal when the different polarization side input signal is “disconnected” or “unmodulated signal”.
The line quality detector receives the demodulated signal on the different polarization side, monitors the line quality, and outputs a second reset activation signal when the line quality is equal to or less than a predetermined value. The cross-polarization interference detector detects the cross-polarization interference of the self-polarization, and when the cross-polarization interference exceeds the synchronization pull-in / out point when the cross-polarization interference removal function is stopped, the cross-polarization interference detector detects the cross-polarization interference. 3 is output. The reset circuit is configured to output the first output from the different polarization side.
, A second reset activation signal, a third reset release signal on the self-polarization side, and a fourth reset activation signal.
The tap coefficients of the transversal filter are initialized in accordance with the reset input signal inputted in any one of the second and the reset states are maintained, and both the first and second reset activate signals are not inputted. If so, release the reset state. Further, when the third reset release signal is input, the reset state is released regardless of the state of the first / second reset activation signal. Furthermore, when the fourth reset activation signal is input, the self-polarized transversal filter is set to the intermittent reset state.

Thus, when the cross-polarization interference amount is equal to or less than the synchronization pull-in point when the cross-polarization interference canceling function is stopped, any failure occurs on the different polarization side and the input signal is interrupted, or If a modulated signal is input, or if the line quality of the received signal on the different polarization side deteriorates, the cross polarization interference canceling function is immediately stopped (reset), and the cross polarization signal having a fault is crossed. Implement polarization elimination so as not to impair the self-polarization. When the cross-polarization interference amount is equal to or higher than the synchronization pull-in point when the cross-polarization interference removal function is stopped, the reset operation on the own polarization is stopped, and quality degradation due to cross-polarization interference of different polarizations occurs. Even in this case, the self-polarization is prevented from being out of synchronization by the reset action. Furthermore, even when the cross-polarization interference amount is large and the synchronization is lost, the intermittent reset of the transversal filter performs the synchronization pull-in operation while performing the adaptive equalization operation, and immediately when the interference amount is improved. Perform synchronization pull-in.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the cross polarization interference canceling apparatus of the present invention. When this configuration is compared with the configuration of the first known example, the outputs 25 and 26 of the quality monitors 107 and 108 are input to the self-polarization reset circuits 111 and 112, respectively. It is characterized in that cross polarization interference detectors 115 and 116 are provided at the output of 110, and outputs of the cross polarization interference detectors are input to reset circuits 111 and 112. Further, the control method of the reset control in the reset circuit is improved.

That is, demodulators 101 and 102 demodulate input signals 1 and 2 of V and H polarizations which are modulated digital data strings, and A / D converters 103 and 104 perform A / D conversion. And outputs the digital data sequence to the subsequent stage. These outputs are input to the transversal filters 109 and 110 of the cross polarization interference cancellers 5 and 6 for orthogonally polarized waves to remove the cross polarization interference. The transversal filter 10 on the different polarization side
Outputs 9 and 110 are subtracted from the self-polarized demodulated digital signals in subtractors 113 and 114 to remove cross-polarized interference, and output as output signals 3 and 4 for V and H polarizations. You.

The input state detectors 105 and 106 detect that the demodulator input signals in the demodulators 101 and 102 are "disconnected" or "unmodulated signal", and reset circuits 112 and 106 on the different polarization side. The first reset activation signals 15 and 16 are output to 111. In addition, the quality monitor 10
Reference numerals 7 and 108 input the output signals of the demodulators 101 and 102 and constantly monitor the line quality. When the line quality is deteriorated, the second reset activation signals 17 and 18 are reset by the reset circuit 112 on the different polarization side. , 111. At the same time, the quality monitors 107 and 108 output the fourth reset activation signal outputs 25 and 26 to the self-polarization reset circuits 111 and 1 when the line quality is degraded and the self-polarization is out of synchronization.
12 is output.

On the other hand, the transversal filter 10
Reference numerals 9 and 110 are adaptive filters having a tap configuration. The output of each tap of the transversal filter is multiplied by a tap coefficient.
The reset values are intermittently reset to the initial values by the reset signals output from 11, 112, and the adaptive equalizing operation is performed except at the time of reset. The cross polarization interference detectors 115 and 116 receive compensation signals output according to the cross polarization interference from the outputs of the transversal filters 109 and 110, and the cross polarization interference stops the cross polarization interference removal function. When it is larger than the synchronization pull-in / out point at the time, third reset release signals 19 and 20 are output as a third reset signal.

The cross polarization interference amount detectors 115 and 116
FIG. 2 shows a specific example of the configuration. The outputs 21 and 22 of the transversal filters 109 and 110 are binary signals composed of multiple bits, and are input to the comparator 202. The comparator 202 compares the multi-bit binary data output of the fixed value generator 201, which is predetermined by a ROM or the like, and indicates the amount of cross-polarization interference at the pull-in / out-of-point when the cross-polarization interference removal function is stopped. And the comparison result outputs 19 and 20
Is output.

The reset circuits 111 and 112 are provided with the first reset activation signals 15 and 16, the second reset activation signals 17 and 18, and the third reset release signal 1.
9, 20 and a fourth reset activation signal 25 and 26 are respectively input. Here, the first, second and fourth reset signals are reset activation when the polarity of the reset signal is "1" and reset release when the polarity is "0". When the polarity of the third reset release signal is “1”, the reset release is prohibited, and when the polarity is “0”, the polarity of the reset release is set. In this case, it is simply configured by the circuit of FIG. In FIG. 3, a rectangular wave oscillator 305 is an oscillator for generating a rectangular wave having a fixed period. The output and each of the reset activation signals and the reset release signals are OR gates 301 and 304 and AND gates 302 and 303. Constitute a logic circuit. In this circuit configuration, the transversal filter is reset when the second reset activation signal, which is the output of the self-polarization quality monitor, is "1", and the reset circuit outputs 23 and 24 are binary. “1”
And the value of “0” are repeated at a specific cycle, and an operation of intermittently resetting the transversal filter is performed. That is,
The reset signals of the outputs 23 and 24 are output from the input state detector 10.
5, 106, the quality monitor 107, 108, and the cross-polarized interference detector 115, 116, the transversal filter is reset to "1" or "1",
An operation of setting the intermittent reset state to repeat “0” or canceling the reset state of “0” is performed.

The operation of the cross polarization interference canceling apparatus having the above configuration will be described. The basic operation of this device, ie, the cross-polarization interference canceling function, and the operation when the cross-polarization interference canceling sphere is stopped according to the state of the different polarization side, ie, the cross polarization in the orthogonally polarized waves The operation in the case where the interference is smaller than the synchronization pull-in / out-of-synchronization point when the cross polarization interference canceling function is stopped is the same as the operation of the first known example, and the description thereof is omitted.

Therefore, consider a case where fading or the like is added to the propagation path, the reception level of both polarizations orthogonal to each other decreases, and the amount of cross-polarization interference in both polarizations increases. The reception level and the cross polarization interference are correlated with each other, and the cross polarization interference tends to increase as the reception level decreases. It is assumed that the V-polarized or H-polarized demodulators 101 and 102 that are orthogonal to each other are in the synchronization pull-in state, and the cross-polarization interference amount is the state indicated by the point (1) in FIG. . Since the input signal of the H-polarization-side demodulator 102 is neither “disconnected” nor “unmodulated signal”, the first reset activation signal 16 is not output by the input state detector 106 for the H-polarization. It remains "0".
At the point (1), if the cross-polarization interference canceller is operating, the signal quality is not degraded in the demodulator 102 until the synchronization is lost. The reset activation signal 18 is also not output and is “0”. The output level of the transversal filter 111 is as shown in FIG.
At the point (1), the cross polarization interference amount detector 115 outputs the output 2 of the transversal filter 109.
2 is compared with the output level of the transversal filter at the synchronization pull-in / out point when the cross polarization interference canceling function is stopped by the comparator 202 in FIG. 0 "is output.
That is, the output of the reset circuit 111 is “0”, and the transversal filter 109 is not in the reset state.

Here, assuming that the amount of cross-polarization interference changes to the point (2) in FIG. 4A, the input signal on the H-polarization side is “cut off” or “unmodulated signal” by the demodulator 102. , The first reset activation signal for the V polarization is not output and remains at “0”. Further, the reception signal on the H polarization side is in a state of being degraded due to cross-polarization interference to the extent that synchronization cannot be pulled in, so that the second reset activation signal 1
At "8", "1" is output. Further, the cross-polarization interference amount detector 115 determines that the cross-polarization interference is greater than the synchronization pull-in / out point when the cross-polarization interference removal function is stopped, and outputs “0” with the reset release signal 19. As a result, FIG.
Becomes a "0" output, the transversal filter 109 does not enter the reset state, and continues the cross-polarization interference removal operation.

The above explanation is based on (1) in FIG.
The case where the amount of cross polarization interference on the H side changes to the point (2), and the case where the amount of cross polarization interference on the V side changes as shown in (1) → (3), the V polarization in the above description. The operation is exactly the same as when the wave and H polarization are rewritten. Therefore, FIG.
In the areas (a) and (b), excellent polarization and V polarization and H polarization can be obtained without causing loss of synchronization. Therefore, the synchronization pull-in range from the time of synchronization pull-in to the time of loss of synchronization is as shown in FIG.

Next, consider a case in which synchronization is performed from a state where both polarizations are out of synchronization. In a state in which the cross polarization interference amount of both polarizations is degraded and out of synchronization occurs in the demodulator of both polarizations at the point (4) in FIG. 4A, the V polarization side demodulator 101,
Since the input signal of the H-polarization-side demodulator 102 is neither “disconnected” nor “unmodulated signal”, the first reset activation signal 16 is input by the input state detectors 105 and 106 for V and H polarizations. Is not output and remains "0". Also,
At point (4), even if the cross-polarization interference canceller is operating, the signal quality of the demodulators 101 and 102 is degraded enough to cause loss of synchronization. The reset activation signal 18 is output and is in the state of “1”. Since the output level of the transversal filter 109 is at the point (4) in FIG. 4 (A), the cross-polarization interference detectors 115 and 116 detect a synchronization pull-in / out point when the cross-polarization interference removal function is stopped. Is compared with the output level of the transversal filter in step (1). V,
Since the demodulators 101 and 102 for each of the H polarizations are out of synchronization, the reset monitoring signals 25 and 26 are output from the quality monitors 107 and 108. After all, the reset circuits 111, 1
12 is a transversal filter 109, 110
Is reset and intermittently reset.

From the above state, if the cross polarization interference amount of the H polarization is improved and the point of (4) in FIG. 4A is changed to the point of (3), the cross polarization of the H polarization is assumed. Since the amount of wave interference reaches the synchronization pull-in point during the operation of the cross interference canceling function and the third reset release signal 20 is activated by the cross polarization interference amount detector 116, the intermittent reset of the transversal filter 110 is performed. Synchronization is performed at times other than the reset state (at the time of adaptive equalization operation).

In the above description, the case where the cross polarization interference amount of the H polarization is improved and the H polarization is synchronized is described. However, the cross polarization interference amount of the V polarization is improved and the V polarization is improved. The same applies to the case where the polarization is synchronized. As a result, the synchronization acquisition range with respect to the cross polarization interference amount is as shown in FIG.

[0029]

As described above, according to the present invention, the cross polarization interference amount is detected by the cross polarization interference amount detector, and when the interference amount is large, the reset from the quality monitor to the cross polarization interference canceller is performed. By providing the reset circuit with a function to release the activation signal, even when the amount of cross-polarization interference exceeds the synchronization pull-in / out point when the cross-polarization interference removal function is operated, both the V and H polarizations are out of synchronization. Is less likely to occur, and the cross polarization interference canceller can be operated for either the V polarization or the H polarization to maintain good channel quality. Further, even when both the V and H polarizations are out of synchronization, the quality monitor and the reset circuit enable the cross polarization interference canceller to perform the interference canceling operation. When the cross polarization interference is improved, the synchronization is pulled in. And the cross-polarization interference amount detector activates a reset release signal, and the reset circuit can release the reset state of the self-polarization cross-polarization interference canceller. When the amount of interference exceeds the synchronization pull-in / out point when the cross-polarization interference canceling function is operated, even if both the V and H polarizations are out of synchronization, one of the polarizations is operated when the cross-polarization interference canceling function is operating. If the amount of interference decreases below the synchronization pull-in point, one of the polarizations can be pulled in synchronously, and if the amount of interference of both polarizations is below the synchronization pull-in point when the cross-polarization interference removal function is operating, the cross polarization interference removal function When stopped Period both polarizations even more pull point is retractable synchronization.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a cross-destructive interference detector according to the present invention.

FIG. 3 is a circuit diagram showing a configuration of a reset circuit according to the present invention.

FIG. 4 is a diagram showing cross polarization interference amounts of V polarization and H polarization orthogonal to each other and a state of pull-in.

FIG. 5 is a block diagram showing a configuration of a first known example of the related art.

FIG. 6 is a block diagram showing a configuration of a second known example of the related art.

[Explanation of symbols]

 1, 2 V, H polarization input signal 3, 4 V, H polarization output signal 5, 6 V, H cross polarization interference canceller 11, 12 Demodulator output (own polarization side) 13, 14 Demodulator output (Different polarization side) 15, 16 First reset activation signal 17, 18 Second reset activation signal 19, 20 Third reset release signal 21, 22, Transversal filter output 23, 24 Reset control signal 25, 26 4 reset activation signal 101, 102 demodulator 103, 104 A / D converter 105, 106 input state detector 107, 108 quality monitor 109, 110 transversal filter 111, 112 reset circuit 113, 114 subtractor 115, 116 Cross polarization interference detector

Claims (4)

(57) [Claims] 1. A cross-polarization interference canceller that receives demodulated signals of received signals of two mutually orthogonal polarized waves and performs an operation of removing a different-polarized-side demodulated signal leaked into a self-polarized-side demodulated signal. And an input state detector that monitors the state of the input signal on the different polarization side, and outputs a first reset activation signal for the own polarization when the input signal is disconnected or unmodulated. Monitoring the line quality on the different polarization side, outputting a second reset activation signal to the own polarization side when the line quality is equal to or less than a predetermined value, and outputting a fourth reset activation signal to the different polarization side And a cross-polarization interference amount detector that outputs a third reset release signal to the self-polarization side when the amount of interference is large based on the cross-polarization interference amount on the self-polarization side. , The first, second, and fourth reset activation signals and the third reset solution A cross-polarization interference canceller, comprising: a reset circuit that inputs a cancellation signal and controls a reset state of the self-polarization cross-polarization interference canceller. 2. The cross polarization interference canceller comprises a transversal filter, and the cross polarization interference amount detector detects a cross polarization interference amount from an output of the transversal filter and performs the third resetting. The cross polarization interference canceller according to claim 1, which outputs a cancellation signal. 3. The cross-polarization interference amount detector compares the cross-polarization interference amount that leads to synchronization pull-in or out-of-synchronization when the cross-polarization interference removal function is stopped with the input cross-polarization interference amount. 3. The cross polarization interference canceller according to claim 2, wherein the third reset release signal is output when the amount is large. 4. The reset circuit performs an operation of releasing a reset state with a third reset release signal with respect to the first and second reset activation signals, and performs a fourth reset activation signal with respect to a fourth reset activation signal. 4. The cross-polarization interference canceller according to claim 2, wherein the transversal filter performs an operation of entering a reset state and an intermittent reset state in which adaptive equalization is repeatedly performed.