JP2882431B2 - 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 dual polarization transmission system,
In particular, it relates to a cross-polarization interference compensator.

[0002]

2. Description of the Related Art In a dual-polarization transmission system for transmitting a digitally modulated signal using two orthogonal polarizations at the same frequency, cross-polarization generated when the discrimination between the two polarizations is deteriorated due to fading or the like. It is common practice to compensate for interference.

FIG. 3 shows an example of a conventional cross polarization interference compensator. Radio frequency reception signal 1 which is a digital modulation signal transmitted with two mutually orthogonal polarizations of the same frequency
01 and 201 are converted into reception signals 102 and 202 in the intermediate frequency band by the receivers 10 'and 20'.

[0004] The received signals 102 and 202 in the intermediate frequency band are demodulated by demodulators 11 and 21 and are digitally converted and output as baseband digital signals 103 and 203. The cross-polarization demodulators 14 and 24 receive the different-polarization-side received signal 20.
2 and 102 are demodulated and converted into digital signals, respectively, and different polarization baseband digital signals 107 and 207 are output.

Transversal filters 15 and 25, which are waveform equalizers for cross-polarization interference compensation, receive different polarization baseband digital signals 107 and 207, respectively, and receive compensation signals 109 and 207 corresponding to the amount of cross-polarization interference. 209 is output. Baseband digital signals 103 and 203 are combined with compensation signals 109 and 209 by combiners 12 and 22, respectively, to compensate for cross-polarized interference components, and combiner outputs 104 and 2 respectively.
04 is output. The combiner outputs 104 and 204 are identified by the discriminators 13 and 23 into main signals 105 and 205 to be sent to subsequent signal processing units and error signals 106 and 206 indicating residual error components after cross polarization interference compensation. . Control signal generators 16 'and 26' provide error signals 106 and 20 respectively.
6 and the different polarization baseband digital signals 107 and 207, and outputs tap weight control signals 108 and 208 for the transversal filters 15 and 25.

A configuration example of the control signal generators 16 'and 26' will be described with reference to FIG. The control signal generator shown in FIG. 4 is a control signal generator for controlling a 3-tap transversal filter, and includes a correlator 30 and counters 31 'to 33'. The correlator 30 outputs the differently polarized baseband digital signal 10.
7 and the error signal 106 are input, and a correlation operation between the two is performed according to the control timing of each tap. To simplify a correlation operation, a signal used for calculation of the other polarization baseband digital signal 10 7 MSB and the error signal 106 of the MS
B, the correlation result is “1” when the polarities of both signals match, and “0” when the polarities do not match, respectively, the first tap correlator output 300, the second tap correlator output 301, and the third tap correlator output 301. It is output as a tap correlator output 302.

[0007] counter 31'～33 'are each counting instrument N stage which receives the correlator output 300 to 302 (N is a natural number), when the corresponding input is "1" counts +1, When it is "0", -1 is counted. Counter 31 '
The upper M bits (M is a positive integer equal to or less than N) of the N-bit counting results of ~ 33 'are output as tap weight control signals 305 to 304 of the transversal filter.

[0008]

However, it is required that the tap weighting coefficient of the transversal filter be kept stable without fluctuation under favorable conditions in which the propagation path is free from fuzzing. . For that purpose, it is desired that the number of stages of the counters that generate the tap weight control signals is sufficiently large. However, when fading occurs in the propagation path, cross polarization discrimination deteriorates, the amount of cross polarization interference increases, and when the amount of cross polarization interference changes over time, the tap weighting coefficient changes at high speed. However, if the number of stages of the counter is large, there is a problem that the change of the tap weighting coefficient becomes slow, and the ability to follow cross polarization interference that changes at a high speed in time is inferior.

[0009] Therefore, the technical problem of the present invention has been made in view of the above drawbacks, with respect to cross polarization interference varies with time, it is to provide a highly followability exchange Sahen wave interference compensator.

[0010]

According to Means for Solving the Problems] The present invention, cross polarization interference has a transversion support Rufiruta, and a stage number variable counter for generating a control signal weighting for controlling the tap weights of the transformer bars Sa Rufiruta In the compensator,
A change speed detecting means for detecting a change speed of the reception electric field from a reception signal of a radio frequency, wherein the change speed is predetermined.
When the threshold value is exceeded, the number of stages of the stage number variable counter
And a number-of-stages control means for reducing the number of steps.

According to the present invention, there is provided a cross-polarization interference compensator used on a receiving side of a dual-polarization transmission system for transmitting a digital modulation signal using polarizations orthogonal to each other at the same frequency, A transversal filter that receives the baseband digital signal after demodulation of the different polarization as an input, and a coupler that combines the baseband digital signal after demodulation of the self-polarization and the output of the transversal filter,
An error signal detector for detecting a residual error included in the output of the coupler, a correlator for performing a correlation operation between the demodulated baseband digital signal of the different polarization and an output of the error signal detector; counting the output of the vessel, the counting result upper M-bi
Tsu DOO (M is a positive number not exceeding the total number of several stages) detecting the stage number variable counter to the force output by the the touch control signal with up weight of the transversal filter, the rate of change of received electric field of the received signal, detection The result exceeds a predetermined threshold
At times, the count value per cycle of the stage variable counter is increased.
A cross-polarization interference compensator characterized by comprising a number-of-stages controller for controlling the number of stages to be switched.

[0012]

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a cross polarization interference compensator according to the present invention. Same received signal 10 1 of radio frequency which is mutually digital modulation signal transmitted by the two orthogonal polarizations of the frequency, 20 1 is converted by the receiver 10 and 20 to receive signals 102 and 202 in the intermediate frequency band You. Further receiver 1
At 0 and 20, the reception electric fields of the radio frequency reception signals 101 and 201 are detected, and the reception electric field monitoring voltages 110 and 210 are output to the control signal generators 16 and 26.

The received signals 102 and 202 of the intermediate frequency band after demodulation by the demodulator 11 and 21, converted to digital, Ru is outputted as a baseband digital signal 103, 203.
The cross-polarization demodulators 14 and 24 receive the different-polarization-side received signal 20.
2,102 The demodulated digital conversion, and outputs the other polarization base over <br/> scan band digital signal 107, 207.

Transversal filters 15 and 25, which are cross-polarization interference compensation waveform equalizers, receive different polarization baseband signals as input, and output compensation signals 109 and 209 corresponding to the amount of cross-polarization interference. . The baseband digital signals 103 and 203 are compensated signals 109 and 20 respectively.
9 and combiners 12 and 22 to compensate for cross-polarized interference components and output as combiner outputs 104 and 204. The combiner outputs 104 and 204 are output from the discriminators 13 and 23 to the main signals 105 and 205 sent to the subsequent signal processing unit and the error signal 10 indicating the residual error component after the cross polarization interference compensation.
6,206.

The control signal generators 16 and 26 receive the error signals 106 and 206 and the differently polarized baseband digital signals 107 and 207, respectively, and output tap weighted control signals 108 and 208 to the transversal filters 15 and 25, respectively. I do.

FIG. 2 shows a configuration example of the control signal generators 16 and 26.
This will be described with reference to FIG. The control signal generator in FIG. 2 is an example of a control signal generator for controlling a three-tap transversal filter, and includes a correlator 30, variable stage counters 31 to 33, a differentiator 34, and a discriminator 35. The differentiator 34 differentiates the received electric field monitoring voltage 110 with respect to time and detects the rate of change. The classifier 35 receives the differentiator output 303 as an input, and when the differentiation result exceeds a predetermined value, that is,
"1" is output when the change speed of the reception electric field exceeds the threshold, and "0" is output when the change speed does not exceed the threshold.

The correlator 30 receives the differently polarized baseband digital signal 107 and the error signal 106 as inputs, and performs a correlation operation between the two in accordance with the control timing of each tap.

[0020] To simplify a correlation operation, a signal used for calculation of the other polarization baseband digital signal 10 7 M
When limited to the SB and the error signal 106 of the MSB, the correlation results when the polarity of the two signals are matched "1", the correlator for the first tap each "0" when they do not match output 30
0, a correlator output 301 for the second tap, and a correlator output 302 for the third tap. The number of stages variable counting device. 31
Reference numeral 33 denotes an N-stage counter (N is a natural number) which receives the correlator outputs 300 to 302 and the discriminator output 304 as inputs. When the discriminator output 304 is "0", the corresponding correlator outputs 300 to 302 are provided. When the discriminator output 304 is "1", when the corresponding correlator output 300-302 is "1", +2 is added. If it is "0", -2 is counted. Number upper M bits of the N bits of the counting result of the variable count unit 31 to 33 (M is a positive integer equal to or smaller than N) and outputs as the weighting control signals 305 to 306 for each tap of the transversal filter.

[0021]

As described above, according to the present invention, the amount of change per unit time of the tap-weighted control signal of the transversal filter which is the cross-polarized interference compensation waveform equalizer is detected by the receiving electric field changing speed detecting means. Can be varied, so that tap weight control with little fluctuation can be performed when there is little change in the state of the propagation path, and cross-polarization interference compensation can be performed when there is a large change in state. Can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of a control signal generator shown in FIG.

FIG. 3 is an example of a conventional cross polarization interference compensator.

FIG. 4 is a block diagram of a control signal generator shown in FIG. 3;

[Explanation of symbols]

 10,10 ', 20,20' receiver 11,21 demodulator 12,22 combiner 13,23 discriminator 14,24 cross polarization demodulator 15,25 transversal filter 16,26 control signal generator 30 correlation Units 31, 32, 33 Variable-stage counters 31 ', 32', 33 'Counters 34 Differentiators 35 Classifiers

Claims (2)

(57) [Claims] And 1. A transversion Sa Rufiruta, in cross polarization interference canceller having a stage number variable counter for generating a weighted control signal for controlling the tap weights of the transformer bars Sa Rufiruta, from a received signal of a radio frequency A changing speed detecting means for detecting a changing speed of the reception electric field, and when the changing speed exceeds a predetermined threshold,
A cross-polarization interference compensator comprising: a number-of-stages control means for reducing the number of stages of the variable-stage counter . 2. A cross-polarization interference compensator used on a receiving side of a dual-polarization transmission system for transmitting a digital modulation signal using polarizations orthogonal to each other at the same frequency, after demodulation of different polarizations. A transversal filter having the baseband digital signal as an input, a combiner for combining the baseband digital signal after demodulation of the self-polarized wave and the output of the transversal filter, and detecting a residual error included in the combiner output and the error signal detector, the other polarization baseband digital signal after demodulation of a correlator which performs correlation calculation between the output of the error signal detector counts the output of the correlator, the count result higher M bits (M
Detected and the stage number variable counter to output the positive number) does not exceed the total number of several stages as the tap weighting control signal of the transversal filter, the rate of change of received electric field of the received signals, the detection result there
A cross-polarization interference compensator comprising: a number-of-stages controller for performing a number-of-stages switching control for increasing a count value per time of the number-of-stages variable counter when a predetermined threshold value is exceeded .