JP2646868B2 - Cross polarization interference compensator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cross polarization interference compensator.

[0002]

2. Description of the Related Art A conventional cross polarization interference compensator will be described with reference to FIG. In FIG. 3, received signals 101 and 201 are received signals in an intermediate frequency band which is a digital modulation signal transmitted with each of two orthogonally polarized waves at the same frequency of a high-frequency signal. , 20
1 are input, and transversal filters 12 and 22, which are cross-polarization interference compensation waveform equalizers that have different polarization equalizer outputs 202 and 102 as inputs, respectively. , The equalizer outputs 102, 202,
The combiners 15 and 25 for combining the compensation signals 106 and 206 output from the transversal filters 12 and 22 and the combiner outputs 103 and 203 are demodulated to obtain the baseband signal 1.
Transversal filter control signals 105 and 2 for controlling the tap weights of the transversal filters 12 and 22 with the demodulators 11 and 21 for outputting the signals 04 and 204 and the baseband signals 104 and 204 as inputs.
And the control signal generators 13 and 23 for outputting a signal 05.

Next, the operation of the conventional example will be described. If the received signals 101 and 201 include cross polarization interference components due to fading in the propagation path, compensation signals 107 and 207 corresponding to the amounts are coupled to the equalizer outputs 102 and 202, and the cross polarization interference is generated. Components are removed. When the state of the propagation path is good, the tap weights of the transversal filters 12 and 22 become zero, and the compensation signals 107 and 207
Level is minimal.

[0004]

In order to increase the cross polarization interference compensation capability of the above-mentioned conventional cross polarization interference compensator,
It is necessary to increase the maximum level of the compensation signal, that is, the level of the compensation signal of the transversal filter. However, if the maximum output level of the compensation signal of the transversal filter is increased, even if the weight of the tap is set to zero in the steady state where there is no cross-polarized interference, a small level signal is output from the transversal filter, and It has the disadvantage of degrading signal quality.

[0005]

The cross-polarization interference compensator of the present invention comprises a first polarization and a second polarization which are orthogonal to each other at the same frequency .
The first and second digital modulation signals transmitted using the polarizations are respectively input and the waveform distortion signals are detected and equalized.
First and second automatic amplitude equalizers, and the second and second
First and second transversal filters each having a digital modulation signal transmitted using one polarization as an input, and inputting the output signal of the first and second transversal filters and receiving the first and second transversal filters . Output from the second automatic amplitude equalizer
Weighting based on the first and second waveform distortion signals
First, a second multiplier, said first, said a second multiplier output first, first synthesizes the output signal of the second automatic amplitude equalizer, and a second coupler Have.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, and FIG.
The same reference numerals as those of the conventional example have the same configuration and function. That is, in this embodiment, the transversal filters 12, 2
The multipliers 1 and 2 are respectively added between the output of the second and the combiners 15 and 25 so as to be controlled by the multiplier weighting signals 108 and 208 output from the automatic amplitude equalizers 10 and 20. Have been.

Next, the main part of the first embodiment will be described. now,
Due to fading in the propagation path, the received signals 101, 20
1 has a waveform distortion, the received signal 10
Since 1,201 contains a cross-polarized interference component,
A compensation signal 10 for compensating the cross polarization interference component by controlling the weight of the multipliers 1 and 2 according to the amount of the waveform distortion.
7, 207 are coupled to the equalizer outputs 102, 202 to remove cross-polarization interference components. When the state of the propagation path is good, neither the waveform distortion nor the cross-polarization interference occurs, so that the transversal filter outputs 106 and 205 are minimized.
The minimum outputs 106 and 206 are multiplied by the multipliers 14 and 2
4 and further, multiplier weighting signals 108 and 20
8 is also minimum, so the weighting amount is also minimum,
The levels of the compensation signals 107 and 207 can be suppressed even lower than in the conventional example.

Next, a second embodiment of the present invention will be described with reference to FIG. The same reference numerals as those in the first embodiment shown in FIG. 1 have the same configurations and functions. That is, in the second embodiment, the first
In this embodiment, the automatic amplitude equalizers 10 and 20 are replaced with the receivers 3 and 4, and the multipliers 1 and 2 are controlled using the multiplier weight signals 108 and 208 detected from the receivers 3 and 4. doing. If the state of the propagation path is good, there is no decrease in the reception input and no cross-polarization interference occurs, so that the multiplier weighting signals 108,
208 is also minimized. Therefore, the transversal filter outputs 106 and 206 are further suppressed by the minimum value of the multiplier weighting signal added to the multipliers 1 and 2. That is, the compensation signals 107 and 207 can be suppressed even smaller than in the conventional example.

[0010]

As described above, the present invention makes use of the fact that there is a correlation between reception input reduction due to fading and waveform distortion and cross-polarization interference generated in a propagation path, and an automatic amplitude equalizer or receiver is used. By providing at the output of the transversal filter a multiplier whose weighting amount changes in accordance with the magnitude of the waveform distortion or cross-polarization interference detected in the above, the dynamic range of the compensation signal level can be easily increased. Therefore, there is an effect that the AC polarization interference compensation capability can be obtained over a large range without deteriorating the quality of the main signal in the steady state where there is no cross polarization interference.

[Brief description of the drawings]

FIG. 1 is a block diagram of a cross polarization interference compensator according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a second embodiment of the present invention.

FIG. 3 is a block diagram of a conventional cross-polarization interference compensator.

[Explanation of symbols]

 1,2 multiplier 3,4 receiver 10,20 automatic amplitude equalizer 11,21 demodulator 12,22 transversal filter 13,23 control signal generator 15,25 coupler

Claims (2)

(57) [Claims] A first polarization orthogonal to each other at the same frequency.
The first and second automatic amplitude equalizers each of which receives the first and second digitally modulated signals transmitted using the second polarization and detects and equalizes a waveform distortion signal, respectively, The said
Second, the first and second transversal filters each having a digital modulation signal transmitted using the first polarization as an input, and the output signal of the first and second transversal filters being input and the second one, from the second automatic amplitude equalizer
First and second multipliers for performing weighting based on the output first and second waveform distortion signals, and the first and second multiplier outputs and the first and second automatic amplitudes and the like. A first and a second combiner for combining an output signal of the modulator and a cross-polarization interference compensator. 2. The method according to claim 1, further comprising the step of :
First and second multiplier weights output from first and second receivers
Using only put signal, said first cross polarization interference compensator according to claim 1, characterized in that the weighting of the second multiplier.