JPS5835419B2 - Cross polarization discrimination compensation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cross-polarization discrimination compensation method for detecting and compensating for interference signals leaking into a desired signal in a cross-polarization wireless transmission method.

Deterioration of cross-polarization discrimination due to rain, which was not a problem with conventionally used radio frequencies, becomes a problem when carrier waves of 10 GHz or more are used, and causes line quality to deteriorate more than that caused by rain attenuation.

This deterioration in the degree of cross-polarization discrimination can be regarded as a type of maze coupling, so it can be compensated for by adding a signal with the same amplitude and opposite phase as the leaked interference signal.

In order to perform this compensation, control for carrier wave regeneration, interference signal detection, and cancellation synthesis is required.

Conventionally, such compensation for cross-polarized wave discrimination was performed by creating a predetermined device separate from the demodulator as a problem of the antenna branching system.

In the present invention, this compensation is performed as part of the demodulation operation, and cross-polarization discrimination can be compensated by adding a small amount of circuitry.

Next, the present invention will be explained in detail based on the drawings.

1 is a horizontally polarized signal input terminal, 2 is a vertically polarized signal input terminal, and each receives a horizontally polarized signal obtained by splitting an incoming cross-polarized signal with an antenna polarization splitter (not shown). (Hereafter H
wave) and a vertically polarized signal (hereinafter referred to as V wave) are input after undergoing processing such as frequency conversion, band filtering, main intermediate frequency amplification, and constant leveling using an automatic gain controller (not shown). be done.

Reference numerals 3 and 4 denote an H-wave dividing circuit and a V-wave dividing circuit, respectively, which divide the H-wave and ■-wave into a predetermined ratio.

The above are common parts for H waves and V waves. 65 is a phase adjustment circuit, 6 is an amplitude adjustment circuit, and 7 is a synthesis circuit, which moderates the phase and amplitude of the V wave guided from the wave dividing circuit 4. It is applied so as to cancel out the interference signal of the V wave leaking into the H wave.

The phase and amplitude control signals are supplied from an adjustment amount calculation circuit 30 described below.

11 and 12 are phase detectors, 13 is a phase adjuster, 14 is a phase shifter, 15 is an identification reproducing circuit, and 16.17 is an output terminal, which outputs the modulated wave that has been modulated in four phases of the H wave. It detects and reproduces and outputs the modulated signal.

Note that the reference signal guided to the phase adjuster 13 here is generated by a carrier wave regeneration circuit described below.

21 is an inverse modulation circuit, which is composed of a circuit including a four-phase modulator, inversely modulates the H wave including the V wave interference signal with the reproduced output of the H wave, and completely cancels the modulation of the H wave. That's what I do.

Reference numeral 22 denotes a carrier wave regeneration circuit, which is constituted by a circuit including a narrow band filter, and is used to regenerate the carrier wave of the H wave.

Reference numeral 23 denotes a level and phase adjustment circuit, which is composed of an amplifier, a variable attenuator, and a phase adjuster.
The adjustment is made so that the wave component is exactly canceled by the output signal of the carrier wave regeneration circuit 22.

If this is done, a V-wave interference signal that is inversely modulated by the H-wave modulation signal will appear at the output of the differential circuit 24.

25.26 is a phase detector, 27 is a phase adjuster, 28 is 4
The phase modulator 29 is a phase shifter, which detects the phase of the signal obtained by inversely modulating the V-wave interference signal with the H-wave modulation signal using the reference signal described below, and determines the magnitude and direction of the interference signal. is detected in the form of two orthogonal signals.

Reference numeral 30 denotes an adjustment amount calculation circuit which determines the magnitude and direction of the interference signal from the two orthogonal signals, calculates the adjustment amounts of the phase adjustment circuit 5 and amplitude adjustment circuit 6, and generates a necessary control signal corresponding to this adjustment amount. is supplied to the phase adjustment circuit 5 and amplitude adjustment circuit 6.

Reference numeral 100 indicates a V-wave processing circuit corresponding to the H-wave processing circuit described above.

110° and 120 are output terminals of the V wave.

50 and 60 are exclusive OR circuits, respectively H wave and V
Exclusive OR the corresponding first and second demodulated output signals of the wave
L, which is supplied to the four-phase modulator 28;

Next, the operation will be explained.

For example, the input signal of the inverse modulator 21 is +4 (1, o, o
, t, ) and (0,0,1,1,), the output signal of the inverse modulator 21 is (o, o, o, o, ) + Q
(0, 1, 0, 1,).

However, here, if is the H-wave signal, if is the V-wave signal, and k is
indicates the degree of leakage, and the numbers in (, , , ) indicate temporal changes in the phase of the modulated signal.

Next, in the differential circuit, TA (o, o, o, o, ) is canceled and only (0, 1, 0, 1,) remains, so the amount of compensation is determined by finding kV from this signal. be able to.

By the way, the leaking V wave signal Q 9 (o, to, t
) to M? To find the phase change over time (0, 1
, 0, 1, ) with a reference signal α(0, 1,
0, 1, ) may be phase-detected.

A reference signal that satisfies such requirements is the exclusive OR circuit 50.
．． At step 60, an exclusive OR signal of the first and second output signals corresponding to the demodulated output of the H wave and the demodulated output of the V wave is generated, and the regenerated ejected wave is output to the four-phase modulator 28. It is obtained by modulating.

It should be noted that since the phase detectors 25 and 26 detect waves on two axes with different reference phases π, the absolute value of the correction amount and the amount of phase shift can be determined from the detected output.

The phase adjuster 5 and amplitude adjuster 6 are adjusted using a control signal corresponding to the correction amount obtained in this way, and control is performed so as to always minimize the interference signal from the V wave.

The above has described the case of canceling and correcting the V wave leaking into the H wave, but the same thing is also performed for canceling the H wave leaking into the V wave.

As described above, according to the present invention, a signal having a desired plane of polarization is first passed through a first inverse modulation circuit to cancel the modulation therein, and then a part of the output signal of this inverse modulation circuit is used to The carrier wave is regenerated, and the signal from the carrier wave regeneration circuit is used to cancel and erase the inversely modulated signal component of the desired polarization plane, and the output signal of the carrier wave regeneration circuit is a demodulated signal detected from each polarization signal. Using the reference wave obtained by four-phase modulation, the remaining signal after the cancellation is phase-detected on two orthogonal axes, and an amount of negative phase cancellation compensation corresponding to the amplitude and phase of the leaking interference wave is obtained. Therefore, it is possible to compensate for cross-polarization discrimination with simple interception.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a block diagram showing an embodiment of the present invention. In the figure, 1...Horizontal polarization signal input terminal, 2
... Vertical polarization signal input terminal, 3 ... H wave division circuit, 4 ... V wave division circuit, 5 ...
...Phase adjustment circuit, 6...Amplitude adjustment circuit, 7
...Composition circuit, 11, 12 ... Phase detector, 13 ... Phase adjustment circuit, 14 ... π ... 7 phase shifter, 15 ... ...Identification reproduction circuit, 16
．． 17...Output terminal, 21...Inverse modulation circuit, 22...Carrier regeneration circuit, 23...
・Adjustment circuit, 24...Differential circuit, 25.26・
... Phase detector, 27 ... Phase adjuster,
28... Four-phase modulator, 29... Ze phase shifter, 30... Adjustment tool calculation circuit, 50.60...
...Exclusive OR circuit, 100...V liquid processing circuit, 110, 120...V wave output terminal.

Claims (1)

[Claims] 1 The modulation signals of the first system and the second system are modulated in four phases using a first carrier signal and a second carrier signal having orthogonal first and second polarization planes, respectively. In the transmitter, an adjustment circuit comprising a level adjustment circuit, a phase adjustment circuit, and a synthesis circuit that adds a reception signal having a second polarization plane to a reception signal having a first polarization plane at a predetermined level and phase; first and second demodulation for demodulating the first system modulation signal and the second system modulation signal from the received signal having one polarization plane and a second polarization plane and extracting each as a four-phase demodulation signal; an inverse circuit for four-phase inverse modulation of a received signal having a first polarization plane with the demodulated signal of the first system and canceling a modulation component by the first modulation signal included in the reception signal having the first polarization plane; a modulation circuit, a carrier regeneration circuit that regenerates a first carrier wave from the output signal of the inverse modulation circuit, and a carrier regeneration circuit that adjusts the phase and amplitude of the output signal of the inverse modulation circuit and the output signal of the carrier wave regeneration circuit to perform inverse phase combination, or An adjustment and differential circuit for canceling the first carrier component contained in the modulation circuit output signal, an exclusive OR signal of corresponding four-phase demodulation signals of the first demodulation circuit and the second demodulation circuit,
a four-phase modulator that modulates the regenerated first carrier wave in four phases; a phase detector that detects the phase of the differential circuit output signal on two orthogonal axes using the output signal of the four-phase modulator; an adjustment amount calculation circuit that calculates the magnitude and phase of a vector of the output signal from two orthogonal output signals and sends a required control signal to the level adjustment circuit and the phase adjustment circuit; A cross-polarization discrimination compensation circuit characterized in that a second carrier wave component is canceled by a signal of a second plane of polarization.