JPS6035843A - Composing device of signal - Google Patents

Abstract

PURPOSE:To allow the titled device to respond to sudden fading by controlling a phase shifter connecting a local oscillator to one mixer by a signal corresponding to the phase difference between the output signals of two mixers of a space diversity. CONSTITUTION:The output of the local oscillator 13 is applied directly to one space diversity receiver and also applied to the other mixer 12 through the phase shifter 14. The output of the mixer 11 is distributed into the same phase respectively by a distributer 16 and the distributed outputs are inputted to phase comparators 18, 19 respectively. The output of the mixer 12 is distributed into the same phase and 90 deg. phase and respective outputs are applied to other inputs of the comparators. The outputs of the comparators 18, 19 become DC/AC signals corresponding to costheta and sintheta of the phase difference of the output signals from the mixers 11, 12 and control the phase shifter 14 through loop filters 20, 21 respectively so that output phases of the mixers 11, 12 inputted to a composer 15 coincide with each other to maximize an output signal level from a terminal 22.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a signal combining device in a space diversity receiving device.

Prior Art and Problems Space diversity receiving devices are known to have a configuration in which, for example, the outputs of mixers of two systems of receiving circuits are combined and output in order to compensate for fluctuations in the received signal level due to fading or the like. In this case, since the phase changes as well as the level of the received signal, it is necessary to match the output phases of the mixers. For this purpose, a phase shifter is provided to control the output phase of the local oscillator. For example, as shown in Fig. 1, the output of the local oscillator 3 is directly input to one mixer 1, and the output of the local oscillator 3 is input to the other mixer 2 via a phase shifter 4. The received high frequency signal is sent to mixer 1.
2, and an intermediate frequency signal is output from mixer 1.2. This intermediate frequency signal is synthesized by the synthesizer 6, outputted to the output terminal IO, and added to the subsequent circuit. Further, the phase shifter 4 is controlled by the compensation circuit 5 so that the output of the combiner 6(2) becomes maximum, that is, so that the 0 phase of the input signal to the combiner 6 matches.

In order to control this phase shifter 4, a phase modulation circuit 7, a synthesizer 8, and an AM detector 9 are provided.

Phase modulator 7 L;l: ? The output signal of mixer 112 is phase modulated by a signal of a predetermined frequency from di compensation circuit 7, and the phase modulated signal is combined with the output signal of mixer 1 in combiner 8. Since the output signal of the synthesizer 8 includes an amplitude component, it is detected by the AM detector 9 and the detected output signal is input to the compensation circuit 5. The compensation circuit 5 controls the amount of phase shift of the phase shifter 4 so that the detection output signal level becomes small.

However, the circuit configuration of the phase modulator 79 combiner 8, AM detector 9, etc. becomes complicated, and the compensation circuit 5 identifies the output signal of the AM detector 9 to control the phase shifter 4. This has the disadvantage that it is difficult to perform control to follow changes in phase due to fading and the like.

(3) Purpose of the Invention It is an object of the present invention to improve the response speed of phase control with a simple configuration and to be able to cope with sudden fading.

Structure of the Invention The present invention provides a method for directly inputting an output signal of a local oscillator to one mixer, inputting the output signal of the local oscillator to the other mixer via a phase shifter, and adjusting the output of the mixer between the one and the other mixer. In a signal synthesis device of a space diversity receiving device that synthesizes and outputs signals, a first phase comparator that compares a phase difference between in-phase components of output signals of the mixer on the π side and the other side; a second phase comparator that compares the phase difference between the in-phase component of the output signal of the mixer and the 90-degree phase difference component of the output signal of the other mixer; and orthogonal comparison of the first and second phase comparators. a phase shifter that controls the phase of the output signal of the local oscillator that inputs the output signal as a control signal to the other mixer; The output signal level of the delay circuit (4) is constituted by a variable attenuator controlled by the control signal, and is characterized by a variable attenuator.Examples will be described in detail below.

Embodiment of the invention FIG. 2 is a block diagram of the main part of an embodiment of the 41 invention.
1 and 12 are mixers corresponding to two systems of receiving circuits, 13 is a local oscillator, 14 is a phase shifter, 15 is a combiner, l [i is a distributor that performs in-phase distribution, and 17 is a distributor that distributes in-phase and 90° phase. 18.19 is a first and second phase comparator,
20 and 21 are loop filters, and 22 is an output terminal for a composite output signal. The intermediate frequency signals of the output signals of the mixers 11 and 12 are combined by a combiner 15 and applied from an output terminal 22 to a downstream circuit 17&. Further, the output signal of the mixer 11 is distributed by the distributor 16 into the same phase and becomes one input of the phase comparator 18, 19, and the output signal of the mixer 12 is distributed by the distributor 17 into the in-phase and 90° phase. The signal is input to the phase comparator 19 of No. 2. Distributor 16.17
The in-phase signal distributed by
A second phase comparator 19 compares the phase of the 90° phase signal distributed in the second phase comparator 19.

When the output signal phases of mixers II and 12 are the same, the phase comparator 18 compares the in-phase components, so the phase comparison output becomes zero, and the phase comparator 19 compares the in-phase components of the output signal of the mixer 11 and Since the phase is compared with the 90° phase of the output signal of the mixer 12, the phase comparison output becomes maximum. Further, when the phase difference between the output signals of the mixers 11 and 12 is 90°, the output signal of the phase comparator 18 becomes maximum and the output signal of the phase comparator 19 becomes zero. That is, with respect to the output signal phase difference θ of the mixers 11 and 12, the output signal of the phase comparator 18 is cos
θ, and the output signal of the phase comparator 19 becomes a quadrature signal corresponding to sin θ.

The output signals of the phase comparators 18 and 19 are passed through the loop filter 2.
0.21 becomes the control input of the phase shifter 14, and the signal phase applied from the local oscillator 13 to the mixer 12 is input to the phase shifter 14.
mixer 11,1 which is controlled by
The output signal phases of 2 (6) match)! - It is controlled so that the

Phase shift V+'t l 44J, for example, as shown in FIG. i! 1! Variable attenuators ATTI to ATT4 that attenuate the output signals of the delay circuits I) L1 to DI, 4 and each delay circuit DI, 1 to l') 1.4 according to the control signal.
It is composed of ′ζ. Delay circuit DLI~DL4
depends on the frequency used (consisting of a delay element that provides a delay amount of a predetermined phase angle, and the delay circuit DL
I has a delay amount of zero. Also, variable attenuator DLI~D L4
is composed of, for example, a pin diode, and controls the amount of attenuation in response to a control signal. Therefore, if the variable attenuators ATT2 to ATT4 are non-conducting (1) and the attenuation amount of the variable attenuator A'r'TI is zero, a signal having the same phase as the output signal phase of the local oscillator 13 will be input to the mixer 12. become. Also, variable attenuator ATT1. ATT3. ATT4
is non-conducting and the variable attenuation 'A: (AT'2) is set to zero, then the output signal of the local oscillator 13 is 90
The phase difference signal (7) is input to the mixer 12. Also, the variable attenuators AT''TI and ATT2 are made non-conductive, and the variable attenuator ATT
3. If the attenuation amount of ATT4 is the same, the local oscillator 13
A signal with a phase difference of 225° with respect to the output signal of mixer 1
2 will be input. That is, the variable attenuator ATTI~
By controlling the attenuation amount of ATT4, the signal phase 36
This means that it can be rotated by 0°.

As described above, the control signals passed through the loop filters 20 and 21 are cos θ and sin θ, corresponding to the phase difference θ between the output signals of the mixers 11 and 12, so these orthogonal control signals cause the variable attenuator ATT1 to -Controls the amount of attenuation of ATT4.

For example, if the output signal phase difference θ of mixers 11 and 12 is 0°
~90°, as shown in FIG. 4, the variable attenuator ATT3. ATT4 is made non-conductive and variable attenuator A
By making the attenuation amount of TTI correspond to cos θ and the attenuation amount of variable attenuator ATT2 to correspond to sin θ, the composite signal of the output signals of variable attenuators ATTI and ATT2 corresponds to the (8) output signal phase of the local oscillator 13. It has a phase difference of θ,
Phase control is performed so that the phases of the output signals of the mixers 1i12 match, and the output signal of the combiner 15 can be maximized.

Effects of the Invention: As explained, the present invention provides a control signal corresponding to the phase difference between the output signals of the mixer 11゜2.
'ζ, and controls the phase of the oscillation output signal input from the local oscillator 13 to the mixer 12 so that the output signal phases of the mixers 11 and 12 match, so that the combined output signal from the combiner 15 is maximized. The phase shifter 14 includes delay circuits DLI each having a different phase angle.
~DL,4 and variable attenuators ATTI~ATT4, the variable attenuator AT corresponds to the control signal.
360 by controlling the attenuation amount of T'l ~ ATTM.
The response speed of the control loop is determined by the time constant of the loop filter 20, 21, but since no complicated circuit is involved, it is easy to provide a phase rotation of (9) Also, by controlling the phase shifter 14, fluctuations in the combined cutting signal level can be suppressed. Therefore, the space diversity receiver has the advantage of being able to control with good responsiveness and reduce fluctuations in the combined output signal even in the face of severe fading in which the received signal level and phase change rapidly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a conventional signal synthesizer, FIG. 2 is a block diagram of the main parts of an embodiment of the present invention, FIG. 3 is a block diagram of a phase shifter, and FIG. This is a phase explanatory diagram. 11.12 is a mixer, 13 is a local oscillator, 14 is a phase shifter, 15 is a combiner, 16.17 is a distributor, 18.19 is a phase comparator, 20.21 is a loop filter, DLI~D
L4 is a delay circuit, and ATTI to ATT4 are variable attenuators. Patent applicant Fujitsu Co., Ltd. Representative Patent Attorney Akira Aitani and 1 other person (10)

Claims (1)

[Claims] The output signal of the local oscillator is directly input to one mixer, the output signal of the local oscillator is input to the other mixer via a phase shifter, and the output signal of the one mixer and the other mixer are input. a first phase comparator that compares a phase difference between in-phase components of output signals of the one mixer and the other mixer; a second phase comparator that compares the phase difference between the in-phase component of the output signal of the second mixer and the 90-degree phase difference component of the output signal of the other mixer; and orthogonal comparison output signals of the first and second phase comparators. a phase shifter that controls the phase of the output signal of the local oscillator that is input as a control signal to the other mixer, and the phase shifter is connected to a delay circuit having delay times of different phase angles, and the delay circuit. and a variable attenuator whose output signal level is controlled by the control signal. (1)