JPS63284938A - Cross polarization interference removing device - Google Patents

Abstract

PURPOSE:To sufficiently show an interference removing ability, by supplying an initial value to a cross polarization interference removing circuit intermittently. CONSTITUTION:A cross polarization interference removing device consists of a pair of cross polarization interference removing circuits 1 and 1', a pair of demodulators 2 and 2', a pair of carrier reproducing devices 3 and 3', a pair of oscillators 4 and 4', and a pair of reset signal generators 5 and 5'. In the asynchronous state of a carrier, the cross polarization interference removing circuits 1 and 1' repeat control and reset, and immediately after the synchronous state of the carrier is set, the cross polarization interference removing circuits 1 and 1' start the control, and the performance of the cross polarization interference removing circuits 1 and 1' is shown sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cross-polarization interference canceling device using a transversal filter, and in particular to a reset method for improving the pull-in characteristics of a cross-polarization interference canceling circuit. Regarding.

[Prior Art] In a digital wireless communication system that uses two mutually orthogonal polarized waves with the intention of making effective use of frequencies, cross-polarized interference caused by the anisotropy of the propagation medium occurs between the two polarized waves. This occurs, resulting in deterioration of line quality. In order to improve this deterioration, a cross-polarization interference removal circuit using a transpersal filter is used.

The polarization side on which cross-polarization interference is to be removed is called self-polarization (for example, horizontal polarization 2).Here, the demodulator for the different polarization side (for example, vertical polarization), which is the interference source, is connected to the transmission line. If the state becomes out of synchronization due to distortion, etc., the control loop of the cross-polarization interference removal circuit on the self-polarization side will diverge.In this case, even if the demodulator on the different polarization side becomes synchronized, the cross-polarization interference removal circuit will diverge. The circuit does not operate normally. Therefore, in an asynchronous state on the side of different polarization, each tag coefficient of the transversal filter is set and held at an initial value (maximum attenuation). A so-called reset operation is required. In this case, each tap coefficient of the cross-polarization interference cancellation circuit is set to the initial value and the control loop is stopped until the carrier synchronization of the demodulator on the opposite polarization side is established, so cross-polarization interference cannot be removed during that time. There is a drawback.

In order to avoid this, in conventional systems, a periodic signal generator, a pseudo-random signal generator, a noise generator, etc. are additionally configured in the cross-polarization interference removal circuit. By intermittently controlling the reset signal generator using these output signals, the cross-polarization interference cancellation function is demonstrated even during carrier non-synchronization of different polarizations, and the operating range of the cross-polarization interference cancellation circuit is expanded. We are trying to expand.

FIG. 4 shows an example of a conventional device. In FIG. 4, there is a synchronization detector, 24 a periodic signal generator, and 5 a reset signal generator.

Now, the IP signal 6 that has undergone cross-polarization interference is input to the cross-polarization interference removal circuit 1. Further, a different polarization IF signal 6' is also input to the cross-polarization interference removal circuit 1.

Signal 7 from which cross-polarization interference included in IF signal 6 has been removed
Output. The signal 7 is demodulated by the demodulator 2.

The data is identified and reproduced to obtain the required data signal.

On the other hand, on the different polarization side, the IF signal 6/ is input to the demodulator 2', the demodulated baseband signal is identified and reproduced by the demodulator 2', and the output signal is used to create a control signal for carrier wave reproduction. do. The carrier wave regeneration control signal is applied to the carrier wave regenerator 3 via the signal line 8, and the carrier wave is regenerated. The carrier wave for demodulation is sent to the demodulator 2 via a regenerated carrier signal line 9.
’ is supplied.

The oscillator 4 is connected to the carrier wave regenerator 3 and the demodulator 2
This is to expand the carrier synchronization pull-in range of No. 1, and performs an oscillation operation when the carrier is out of synchronization. The configuration and operation of this carrier wave regenerator 3 and oscillator 4 are disclosed in Japanese Patent Application Laid-open No. 57
Since it is described in detail in No. 131151 "Carrier Regeneration Circuit", it will be omitted here.

When the demodulator 2' falls into carrier wave asynchronous state due to transmission line distortion on the side of different polarization, the 9 oscillator 4 starts oscillating. The output signal of this oscillator 4 is transmitted to a carrier wave asynchronous detector 20 via a signal line 21.
9 and detects the output signal of the oscillator 4. Oscillator 4
The oscillation frequency is generally about several tens to several hundreds of Hz, and the detection time constant of the carrier asynchronous detector 20 has a sufficiently large value with respect to that frequency. This carrier asynchronous detector 2
A detection signal of 0 outputs a 1H () (a) level when asynchronous and a “L” (low) level when synchronized. Generates a 9-cycle signal when the detection signal is at “H” level,
""L#L# level period signal is not generated and "L" level is maintained. The output signal of this periodic signal generator 24 is sent via a signal line 17 to a reset signal generator 5 for setting the tap coefficients of each tap of the transparsal filter section of the cross-polarization interference removal circuit 1 to initial values. Control.

An example of the configuration of the reset signal generator 5 is shown in FIG.

In FIG. 5, 47.12 is a control signal for the cross-polarization interference removal circuit 1, as also shown in FIG.

Both are connected to a cross-polarization interference cancellation circuit l.

46 is an initial value setter for the cross-polarization interference removal circuit 1;
This signal is connected to switch 45. The operation of the switch 45 is controlled by the control signal 4 output from the cross-polarization interference removal circuit 1.
7 and the output signal of the initial value setter 46 to the periodic signal generator 2.
4 and outputs it to the cross-polarization interference removal circuit 1 via the signal line 12. Here, the switch 45 selects the control signal from the cross-polarization interference removal circuit 1 when the output signal 17 of the periodic signal generator 24 is "L#", and @
Since the output of the initial value setter 46 is selected when the signal is "H", resetting is performed intermittently during the operation of the two oscillators 40, that is, when carrier waves are asynchronous, and the period during which cross-polarization interference can be removed can be improved.

The above explanation is for the IF band cross-polarization interference canceling device, but the same can be said for the baseband band cross-polarization interference canceling device.

[Problems to be Solved by the Invention] However, in the conventional device, the upper limit of the frequency of the oscillator 4 that operates when carrier waves are not synchronized is limited in order to make it easier to establish carrier wave synchronization, and a relatively low frequency is selected. For this reason, the detection time constant of the carrier asynchronous detector 20 that detects this frequency signal must be set to a large value, requiring a long detection time. For this reason, there is a drawback in that the cross-polarization interference removal characteristics of the cross-polarization interference removal device are greatly reduced.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the cross-polarization interference canceling device of the present invention has two methods in which the control signal of the control signal switch for each tap of the transparsal filter section is transferred to the demodulator. The oscillator output is used directly to extend the carrier synchronization range.

Specifically, the first cross-polarization interference canceling device according to the present invention receives two polarization signals as input and outputs a signal with cross-polarization interference removed from one polarization signal. a removal circuit; a pair of demodulators that demodulate the signal and output a baseband signal and an identification-regenerated data signal;
A pair of carrier wave regenerators connected to the demodulator and outputting a recovered carrier wave to the demodulator; and a pair of oscillators connected to the carrier wave regenerator and operating in oscillation when the carrier waves are asynchronous.

The oscillator output on the side of a different polarization different from the self-polarization is input,
and a pair of reset signal generators for providing an initial value to the cross-polarization interference cancellation circuit.

The reset signal generator is intermittently controlled by the output of the oscillator on the different polarization side when carriers on the different polarization side are out of synchronization, thereby intermittently giving an initial value to the cross polarization interference removal circuit. Features.

In addition, a second device according to the present invention includes a pair of first demodulators each receiving two polarized waves as inputs, demodulating the input signals, and outputting a baseband signal and an identification-regenerated data signal; The two baseband signals are input, and the baseband signals from which cross-polarization interference has been removed are each
a pair of cross-polarization interference cancellation circuits to output, a pair of second demodulators that demodulate the output of the cross-polarization interference cancellation circuits; A pair of carrier wave regenerators output to a demodulator, a pair of oscillators connected to the carrier wave regenerators and oscillating when the carrier waves are not synchronized, and the oscillator output of a different polarization side different from the self-polarized wave is input, and a pair of reset signal generators for giving an initial value to a polarization interference removal circuit, and the reset signal generator is intermittently activated by the output of the oscillator on the different polarization side when carriers on the different polarization side are not synchronized. By controlling.

The present invention is characterized in that an initial value is intermittently given to the cross-polarization interference cancellation circuit.

Furthermore, a third device according to the present invention includes a pair of demodulators each inputting the two polarized signals, demodulating the input signals, and outputting a discriminately reproduced data signal; As input.

a pair of cross-polarization interference removal circuits that output a data signal from which cross-polarization interference has been removed; and a pair of carrier waves that are connected to the demodulator and the cross-polarization interference removal circuit and output a recovered carrier wave to the demodulator. With a regenerator.

A pair of oscillators that are connected to the carrier regenerator and oscillate when carriers are not synchronized, and the output of the oscillator on the side of a different polarization that is different from the self-polarization are input, and an initial value is input to the cross-polarization interference removal circuit on the self-polarization side. a pair of reset signal generators that output a reset signal to give a reset signal, and the reset signal generator is intermittently controlled by the output of the oscillator on the different polarization side when carriers on the different polarization side are out of synchronization. The present invention is characterized in that an initial value is intermittently given to the cross-polarization interference removal circuit on the self-polarization side.

[Example code] An embodiment of the present invention will be described below.

FIG. 1 shows a first embodiment of the present invention, which is an IF band cross-polarization interference removal device. In this figure.

The configuration for two polarized waves (vertical polarization, horizontal polarization) is shown, including a pair of cross-polarization interference removal circuits 1゜11, a pair of demodulators 2.2', and a pair of carrier wave regenerators 3゜. 3', a pair of oscillators 4, 4', a pair of reset signal generators 5, 5'
Consists of.

Hereinafter, the operation on the self-polarized side will be described, assuming that the demodulator 2 side is the self-polarized side and the demodulator 2' side is the different-polarized side. The IF input signal 6 subjected to cross-polarization interference is input to the cross-polarization interference removal circuit 1, and the interference component is removed based on the different polarization IF input signal 6'. The signal 7 from which interference has been removed is applied to a demodulator 2, and the demodulator 2 obtains a desired data signal 101. Demodulator 2 also. A control signal 8 for carrier wave regeneration is applied to the carrier wave regenerator 3. A carrier wave regenerator 3 regenerates the carrier wave and applies a regenerated carrier wave 9 to the demodulator 2.

In this configuration, one oscillator 4 is connected to the carrier regenerator 3 in order to expand the carrier synchronization range.

A detailed description of the operation is given in the above-mentioned Japanese Patent Laid-Open No. 57-131151, so the explanation will be omitted.

In order to give an initial value to each tap coefficient of the cross-polarization interference removal circuit 1, the oscillator 4' and the reset signal generator 5' on the different polarization side operate as follows. Namely.

When the oscillator 4' starts the oscillation operation by the signal 19' from the demodulator 2', the reset signal generator 5' starts the oscillator 41.
According to the output waveform of the cross-polarization interference removal circuit 1, either the output control signal 47 or a signal whose initial value is each tap coefficient is selected, and the cross-polarization interference removal circuit 1 selects the control signal 47 as the control signal 12. Output to.

The reset signal generator 5' is the same as that described in FIG. That is, the switching control of the switching device 45 shown in FIG. 5 is carried out by the output 11' of the oscillator 4'.

When the oscillator 4' is in oscillation operation, that is, when the carrier waves on the side of different polarizations are not synchronized, the control signal 47 inputted from the cross-polarization interference removal circuit 1 is selected, for example, when the amplitude of one oscillation waveform is of positive polarity. Conversely, for negative polarity.

Select a signal with each tap as an initial value. In this way, the cross-polarization interference removal circuit 1 repeats control and reset when the carriers are out of synchronization.

It is possible that the oscillator 4' stops oscillating during carrier synchronization on the side of different polarization, and that the output of the oscillator 4' when the oscillation is stopped has the positive polarity described above. performs control operations. As a result, the cross-polarization interference elimination circuit 1 starts controlling at the same time that the carrier synchronization state is achieved on the different polarization side, and the performance of the cross-polarization interference elimination circuit 1 can be fully exhibited.

Figure 1 is an example of an IF band cross-polarization interference canceller.
A similar improvement can be expected for the baseband band cross-polarization interference canceling device using the same method. An example is shown in FIG.

In FIG. 2, the same parts as in FIG. 1 are given the same numbers. In this embodiment, the cross-polarization interference removal circuit 1 side is provided with a first demodulator 201 on its input side and a second demodulator 202 on its output side. The first demodulator 201 reproduces the baseband signal 14 from the input signal 6, and the cross-polarization interference removal circuit 1 outputs the baseband signal 18 from which interference has been removed. Further, the carrier wave regenerator 3
receiving the control signal 8 from the demodulator 202 of the first demodulator 2
Add reproduced carrier wave 9 to 01.

The operations of the carrier wave regenerator 3, 3' and the oscillator 4; 4'+'J set signal generators 5, 5' are the same as in the case of the IF band cross-polarization interference canceling device described above.

FIG. 3 shows a third embodiment of the present invention, and shows the configuration of an apparatus for removing cross-polarization interference in a reproduced data signal. The carrier wave regenerator 3 (3') is a cross-polarization interference removal circuit 1
(1') to control signal 15 (15') for carrier wave regeneration
), the reproduced carrier wave 9 (9') is returned to the demodulator 2 (2'). Demodulator 2 (2') receives data signal 1
Play 01 (101').

The cross-polarization interference cancellation circuit 1 (),') outputs a data signal 102 (102') from which interference has been removed. Oscillator 4 (
4'), and the operation of the IJ upper set signal generator 5 (5') is the same as in FIG.

[Effects of the Invention] As explained above, by using the cross-polarization interference removal device according to the present invention, it is possible to minimize the influence of resetting in a carrier asynchronous state on the side of different polarization,
The interference removal ability of the cross-polarization interference removal device can be fully demonstrated.

below string date

[Brief explanation of drawings]

FIG. 1 shows an implementation U of the IF band cross-polarization interference canceling device of the present invention.
2 is a block diagram of an embodiment of the base/S nodal band cross-polarization interference canceling device of the present invention, and FIG. 3 is a block diagram of a third embodiment of the present invention. FIG. 4 is a block diagram of an embodiment of a conventional IF band cross-polarization interference canceling device, and FIG. 5 shows an embodiment of the reset signal generator 5. In FIG. 6.6I...IF band input signal t7, 7's14*14
'... Baseband signal, 8, 8'... Control signal for carrier wave regeneration, 9, 9'... Regenerated carrier wave. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. In an orthogonally polarized digital radio system that uses two polarized waves orthogonal to each other, a signal obtained by taking the two polarized signals as input and removing cross-polarization interference from one polarized signal. a pair of cross-polarization interference cancellation circuits that output a signal, a pair of demodulators that demodulate the signal and output a baseband signal and an identification-regenerated data signal; a pair of carrier wave regenerators that output to the
A pair of oscillators connected to the carrier wave regenerator and operating in oscillation when the carrier waves are out of synchronization, and a pair of oscillators that input an output of the oscillator on the side of a polarized wave different from the self-polarized wave, and provide an initial value to the cross-polarization interference removal circuit. and a pair of reset signal generators, and the cross-polarization interference is removed by intermittently controlling the reset signal generator by the output of the oscillator on the different polarization side when the carriers on the different polarization side are not synchronized. A cross-polarization interference removal device characterized by intermittently giving an initial value to a circuit. 2. In an orthogonally polarized digital radio system that uses two polarized waves that are orthogonal to each other, the two polarized signals are input, the input signals are demodulated, and a baseband signal and a discriminatively reproduced data signal are output. a pair of first demodulators that receive the two baseband signals and output baseband signals from which cross-polarization interference has been removed; a pair of second demodulators for demodulating the output of the circuit;
a pair of carrier wave regenerators connected to the demodulator and outputting a recovered carrier wave to the first demodulator; a pair of oscillators connected to the carrier wave regenerators and operating in oscillation when the carrier waves are asynchronous;
The oscillator output on the side of a different polarization different from the self-polarization is input,
and a pair of reset signal generators for giving an initial value to the cross-polarization interference removal circuit, and the reset signal generator is activated by the output of the oscillator on the different polarization side when the carriers on the different polarization side are out of synchronization. A cross-polarization interference canceling device characterized in that an initial value is intermittently given to the cross-polarization interference canceling circuit by performing intermittent control. 3. In an orthogonally polarized digital radio system that uses two polarized waves orthogonal to each other, a pair of demodulators receives the two polarized signals as input, demodulates the input signals, and outputs identified and reproduced data signals. a pair of cross-polarization interference cancellation circuits that receive the two data signals as input and output a data signal from which cross-polarization interference has been removed; A pair of carrier wave regenerators that output reproduced waves to the demodulator, a pair of oscillators connected to the carrier wave regenerators and oscillating when the carrier waves are not synchronized, and an output of the oscillator on the side of a different polarization different from the self-polarized wave as inputs. , and a pair of reset signal generators that output a reset signal for giving an initial value to the cross-polarization interference removal circuit on the self-polarization side, and when the carriers on the cross-polarization side are out of synchronization, the cross-polarization interference canceling circuit on the cross-polarization side A cross-polarization interference canceling device, characterized in that an initial value is intermittently given to the cross-polarization interference canceling circuit on the self-polarization side by intermittently controlling the reset signal generator using an output of an oscillator.