JPS5835418B2 - 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-polarization discrimination has been performed by constructing a predetermined device separate from the demodulator as a part 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 wave obtained by splitting the incoming cross-polarized signal with an antenna polarization splitter (not shown). Signal (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.

5 is a phase adjustment circuit, 16 is an amplitude adjustment circuit, and 7 is a synthesis circuit. The signal is applied to cancel the interference signal.

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 regeneration circuit 22, which will be 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 differential circuit 24 adjusts so that the inversely modulated H wave component included in the output signal of the adjustment circuit 23 is just 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 is a four-phase modulator in which the V-wave interference signal is inversely modulated by the H-wave modulation signal and further inversely modulated to eliminate temporal changes in the phase of the interference signal; 26.
27 is a phase detector, 28 is a phase adjuster, and 29 is a 7 phase shifter. These detect the phase of the V-wave signal from which the phase change has been removed, and determine the magnitude and direction of the interference signal between the two orthogonal signals. It is something that is detected in shape.

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 V wave output terminals.

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, 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 H(1,0,0,1
, ) to (0,0,1,1,), the inverse modulator 21
The output signal C, H (0, O, O, O,) + K < I
(0,1,0,1,) level.

However, here n is the H wave signal, ■ is the V wave signal,
K is the degree of leakage, and the numbers in (, , , ) indicate temporal changes in the phase of the modulation signal.

Next, H (0, O, 0, 0,) is canceled in the differential circuit, and K
Since only V(1,0,1,0,) remains, the amount of compensation can be determined by determining KV from this signal.

By the way, this leaking V wave signal i? (0,1,0,
1,), the inverse modulator 25 eliminates the temporal change in the phase of (0, 1, 0, 1,) from the leaked V wave signal, and then the recovered carrier wave is shifted 7 times. 2 that matched
It is sufficient to perform phase detection using one signal as a reference wave.

In order to eliminate the temporal change in the phase of (0, 1, 0, 1,) in the leaked V-wave signal, the H-wave demodulation output and the V-wave demodulation output are each Create an exclusive OR signal of the corresponding first and second output signals, and use this signal to convert the leakage V wave signal to (0,1°0.1.)
It is sufficient to perform four-phase modulation using the four-phase modulator 25.

Incidentally, since the phase detectors 25 and 26 detect the reference phase π on two different axes, the absolute value of the correction amount and the phase shift amount 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 the first inverse modulation circuit to cancel the modulation there, and then a part of the output signal of this inverse modulation circuit is used to While regenerating the carrier wave, the signal from this carrier wave regeneration circuit is used to cancel and erase the signal component of the inversely modulated wavefront of the equipment, and the remaining signal is generated by a combination of demodulated signals detected from each polarized signal. After four-phase modulation, phase detection is performed on two orthogonal axes to obtain the amount of negative phase cancellation compensation that corresponds to the amplitude and phase of the leaking interference wave. The effect of being able to perform compensation can be obtained.

[Brief explanation of drawings]

The figure is a configuration 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 : synthesis circuit, 11, 12: phase detector, 13: phase adjustment circuit, 1
4 near phase shifter, 15: identification regeneration circuit, 16.17: output terminal, 21: inverse modulation circuit, 22: carrier wave regeneration circuit, 23
: Adjustment circuit, 24: Differential circuit, 25: Four-phase modulator, 26
．． 27, π: Phase detector, 28: Phase adjuster, 29. hundred phase shifter, 3
0: Adjustment tool calculation circuit, 50, 60: Exclusive OR circuit, 1
00: V wave processing circuit, 110, 120: ■ 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; an adjustment and differential circuit for canceling the first carrier wave 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 performs four-phase modulation of a differential circuit output signal; a phase detector that performs phase detection on two orthogonal axes of the four-phase modulator output signal using the carrier regeneration circuit output signal; and two orthogonal axes of the phase detector. an adjustment amount calculation circuit that calculates the magnitude and phase of the vector of the output signal from the two output signals and selects a desired control signal for the level adjustment circuit and the phase adjustment circuit; The second carrier component
A cross-polarization discrimination compensation circuit characterized in that the cross-polarization discrimination compensation circuit is configured to cancel the polarization by a signal of a polarization plane.