JP2577837B2 - Space diversity controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a space diversity control device for controlling a phase shifter for performing two-route synthesis of an in-phase combined space diversity receiver in digital microwave communication.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram showing a conventional space diversity control apparatus. In the figure, reference numeral 1 denotes input of combined information of an in-phase combined space diversity receiver output from a detector 18 (see FIG. 8). An input terminal 2 is an analog-to-digital converter (hereinafter, referred to as an A / D converter) for digitally converting the combined information input from the input terminal 1, and a temporary storage unit 3 is a digital converter for converting the combined information to the A / D converter 2. A holding circuit for storing the data; 4 a comparison circuit for comparing the current synthesized information digitally converted by the A / D converter 2 with the synthesized information before a predetermined time temporarily stored in the holding circuit 3;
Reference numeral 5 denotes an up / down counter (hereinafter referred to as a U / D counter) that counts up or down in accordance with the comparison result of the comparison circuit 4, and 6 denotes U / D based on the presence or absence of a signal output from the A terminal of the comparison circuit 4. A U / D conversion circuit 7 for determining the counting direction of the counter 5; and an OR circuit 7 for generating a clock for operating the U / D counter 5 by taking the logical sum of the signals output from the A and B terminals of the comparison circuit 4 It is.

[0003] 8 stores sine wave data in advance,
A memory (hereinafter referred to as a ROM) that is addressed by the count value of the U / D counter 5 and outputs the waveform data in θ ° steps, and 9 stores waveform data of a cosine wave in advance, A memory (hereinafter referred to as a ROM) which is addressed by a numerical value and outputs the waveform data in θ ° steps, and ROM 11 and ROM 11
The phase shifter 16 (FIG. 8) of the in-phase combining space diversity receiver is obtained by converting each waveform data output from 9 into analog.
Digital-to-analog converter (hereinafter referred to as a D / A converter) for supplying the first and second drive signals to
Reference numeral 12 denotes an output terminal from which a first drive signal is output, and reference numeral 13 denotes an output terminal from which a second drive signal is output.

FIG. 8 is a block diagram showing an example of an in-phase combined space diversity receiver to which the present invention and a conventional space diversity control device are applied.
In the figure, reference numerals 14 and 15 denote input terminals to which received signals from antennas arranged at predetermined intervals are inputted.
Reference numeral 6 denotes a phase shifter that shifts the phase of one of the received signals, for example, the received signal input to the input terminal 15, and performs route combining in the in-phase combining space diversity system. Reference numeral 17 denotes a synthesizing circuit for synthesizing the received signal input to the input terminal 14 and the received signal phase-shifted by the phase shifter 16, 18 a detector for detecting the signal output from the synthesizing circuit 17, 19 Is an output terminal from which the detection output of the detector 18 is output as in-phase synthesis space diversity synthesis result as synthesis information. Reference numeral 20 denotes a space diversity control device that receives the detection output of the detector 18 and generates the first and second drive signals of the phase shifter 16, and is configured, for example, as shown in FIG.

FIG. 9 is a block diagram showing an example of the phase shifter 16. As shown in FIG. The phase shifter 16 is a vector combining phase shifter, and includes a pair of balanced modulators 21 and 22 and a 90 ° distributor 23.
And an in-phase synthesizer 24. In the figure, reference numeral 25 denotes an input terminal to which a reception signal from the input terminal 15 is input, reference numeral 26 denotes an output terminal to which an output signal to the synthesis circuit 17 is output, and reference numeral 27 denotes a first drive from the space diversity controller 20. An input terminal to which a signal is input, 28
Is an input terminal to which the second drive signal is input.

Next, the operation will be described. The input terminal 1 of the space diversity control device shown in FIG.
, The detection output signal (combined information) of the detector 18 is input. The input synthesis information is sent to the A / D converter 2, converted into an N-bit digital signal, and temporarily stored in the holding circuit 3.

The output of the A / D converter 2 is supplied to a comparison circuit 4
The comparison circuit 4 compares the current data with the previous data that is temporarily stored in the holding circuit 3 and that is a predetermined time before. If the comparison result indicates that the current data is smaller than the previous data, a signal is output from the A terminal, and the U / D conversion circuit 6 operates, whereby the U / D conversion circuit 6 operates.
The D counter 5 counts in the decreasing direction. On the other hand, when the previous data is larger than the current data, the U / D counter 5 counts in the increasing direction.

The count value of the U / D counter 5 is stored in a ROM 8
And 9 sequentially, and the ROMs 8 and 9 read out the waveform data addressed and stored according to the count value. Therefore, from the ROM 8, θ °
Waveform data that changes in a sine wave form is read out in steps, and waveform data that changes in a sine wave form in a θ ° step shifted by 90 ° from the ROM 9, that is, waveform data that changes in a cosine wave form, is read from the ROM 9. Is read.

The waveform data read from the ROMs 8 and 9 are sent to D / A converters 10 and 11 where they are converted into analog signals.
6 as a drive signal. Therefore, the output terminal 12
Outputs a first drive signal based on a sine wave signal, and an output terminal 13 outputs a second drive signal based on a cosine wave signal. The relationship between the first drive signal and the second drive signal is as shown in FIG.

Now, the first and second drive signals shown in FIG. 11 are supplied from the input terminals 27 and 28 of the phase shifter 16 to the balanced modulator 2.
When the signal is input to 1 or 22, the amplitude in each phase has such a characteristic that the amplitude slightly drops at an odd multiple of 45 ° as shown in FIG.

[0011] This is because in the phase of an odd multiple of 45 °, the signal voltages of both the first drive signal and the second drive signal are low, and they operate near the diffusion potential of the diode. This is because the region where the linearity in the passing impedance 22 is deteriorated is used.

The balanced modulator 21 in the phase shifter 16
Reference numeral 22 denotes a lattice-type circuit composed of four diodes. One of the lattice-type circuits is applied with a first drive signal, and the other is supplied with a second drive signal. A current determined by the diode impedance corresponding to the applied drive signal voltage flows through the diodes constituting the balanced modulators 21 and 22, so that the passing impedance of the balanced modulators 21 and 22 becomes the required impedance. As a result of the vector synthesis at the output units 21 and 22, a signal having a required phase is obtained. Also, depending on the environmental conditions of the device, particularly the change in the ambient temperature, each of the balanced modulators 21 and 2
2 changes. Therefore, when the ambient temperature increases, the diode impedance decreases, and the passing impedance of the balanced modulators 21 and 22 decreases. In such a case, the amplitude of the combined vector on the phase plane increases, and the amplitude fluctuation in each phase increases. On the other hand, when the ambient temperature decreases, the diode impedance increases, so that
-The passing impedance of 22 becomes large. In such a case, the amplitude of the combined vector on the phase plane becomes small, and the amplitude fluctuation in each phase becomes large. In FIG.
5 shows the variation of the combined vector on the phase plane when the ambient temperature changes.

[0013]

Since the conventional space diversity control device is constructed as described above, R
The signal output from the OM is a sine wave whose phase is shifted by 90 ° from each other, and is used as the first and second drive signals. There is a problem that a drop appears at the point and the control accuracy of the space diversity combining method deteriorates. Also, the diode impedance of the balanced modulator changes due to a change in the ambient temperature, so that the passing impedance of the balanced modulator changes. As a result, the amplitude variation of the combined vector of the phase shifter increases, and the control accuracy of the space diversity combining method becomes poor. There were problems such as deterioration.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to prevent the amplitude of a combined vector of a phase shifter from dropping at a predetermined phase point.
An object of the present invention is to obtain a space diversity control device with high control accuracy by suppressing amplitude fluctuation of a combined vector caused by fluctuation of an ambient temperature.

[0015]

According to a first aspect of the present invention, there is provided a space diversity control apparatus for generating a sine wave and a cosine wave in which predetermined constants of a positive polarity or a negative polarity are superimposed in advance in accordance with a phase. A memory is provided for outputting each waveform data from an address stored and corresponding to the count value of the up / down counter.

In the space diversity control apparatus according to the second aspect of the present invention, a resistor is connected in series between the digital / analog converter and the phase shifter.

Further, the space diversity control device according to the third aspect of the present invention is provided with a voltage amplification circuit for changing the power level of the drive signal supplied to the phase shifter by the digital / analog converter in accordance with the ambient temperature. Things.

[0018]

According to the first aspect of the present invention, there is provided a space diversity control apparatus comprising: a sine wave and a cosine wave in which a predetermined constant of positive or negative polarity is superimposed in advance from an address corresponding to a count value of an up / down counter in accordance with a phase. Is provided, the amplitude of the combined vector falling at a predetermined phase point is compensated by the predetermined constant.

In the space diversity control apparatus according to the second aspect of the present invention, a resistor is connected in series between the digital-to-analog converter and the phase shifter. The current flowing through the diode becomes constant.

The space diversity control device according to the third aspect of the present invention includes a voltage amplifying circuit for changing a voltage level of a drive signal supplied to the phase shifter by the digital / analog converter in accordance with an ambient temperature. By
Even if the ambient temperature fluctuates, the DC impedance of the diode in the balanced modulator becomes constant.

[0021]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a space diversity control apparatus according to an embodiment of the present invention. In the figure, the same reference numerals as those in the related art denote the same or corresponding parts, and a description thereof will be omitted.

Reference numeral 27 denotes a predetermined constant of positive polarity or negative polarity depending on the phase in advance, that is, + Δ in a phase range of 0 ° to 180 °.
A constant corresponding to a DC voltage of V, and a sine wave waveform data on which a constant corresponding to a DC voltage of −ΔV is superimposed in a phase range of 180 ° to 360 °, corresponding to the count value of the U / D counter 5 A memory (hereinafter referred to as a ROM) for outputting the waveform data from the set address is a predetermined constant of positive polarity or negative polarity according to the phase in advance, that is, 0 ° to 90 °.
And a constant corresponding to a DC voltage of + ΔV in a phase range of 270 ° to 360 °, and −Δ in a phase range of 90 ° to 270 °.
A memory (hereinafter referred to as ROM) that stores waveform data of a cosine wave on which a constant corresponding to a DC voltage of V is superimposed and outputs the waveform data from an address corresponding to the count value of the U / D counter 5.

Next, the operation will be described. Here, the basic operation is the same as in the conventional case, and a description thereof will be omitted.

The ROM 27 is accessed using the count value of the U / D counter 5 as an address, and data that changes in a sine wave form superimposed on a rectangular wave whose polarity is inverted at 0 ° and 180 ° is read in θ ° steps. Also, ROM
28 is similarly accessed, and data that changes in a cosine wave shape by being superimposed on a rectangular wave whose polarity is inverted at 90 ° and 270 ° is read in θ ° steps.

The D / A converters 10 and 11 use this ROM
The data read from 27 or 28 is converted into a first drive signal and a second drive signal by analog signals. Therefore, from the output terminals 12 and 13, the waveforms are shown in FIG. 4, the first drive signal by a modified sine wave having a voltage change of 2 · ΔV in steps at 0 ° (360 °) and 180 °, or A second drive signal based on a modified cosine wave having a voltage change of 2 · ΔV in a stepwise manner at 90 ° and 270 ° is sent to the phase shifter 16.

In the phase shifter 16 which has received the first and second drive signals, the balanced modulators 21 and 22 have 45
It operates without using a region near the diffusion potential of the diode where the linearity of the passing impedance is deteriorated even in the phase of an odd multiple of °. Therefore, the output signal of the phase shifter 16 is as shown in FIG.
As shown in (1), a constant amplitude characteristic is obtained irrespective of the phase point.

Embodiment 2 FIG. FIG. 2 is a block diagram showing a space diversity controller according to an embodiment of the present invention. In FIG. 2, reference numerals 29 and 30 are connected between the D / A converters 10 and 11 and the phase shifter 16. It is a resistor.

Next, the operation will be described. FIG. 6 shows the voltage-current characteristics of the diodes constituting each of the balanced modulators 21 and 22.
It is like. It is necessary to use the balanced modulators 21 and 22 in an area where the linearity of the voltage-current characteristics is good. However, as shown in FIG. 6, the voltage-current characteristics of the diode change sensitively in accordance with the temperature change, and the ambient temperature changes. When the voltage rises, the diffusion potential decreases, and the DC impedance decreases at the same voltage to increase the current. On the other hand, when the ambient temperature decreases, the diffusion potential increases, the DC impedance increases at the same voltage, and the current decreases. Therefore, in order to eliminate a change in current due to a change in ambient temperature, a drive voltage is supplied via the resistors 29 and 30. As a result, when the temperature rises, the DC impedance of the diode decreases and the current increases. However, a voltage drop occurs in the resistors 29 and 30 by the increase in the current. The current flowing through the channel is reduced, and as a result, the current is kept constant. On the other hand, when the ambient temperature drops, the current is kept constant by the opposite effect of the rise. Since the current is kept constant, the amplitude of the combined vector of the phase shifter 16 is kept constant even when the ambient temperature changes.

Embodiment 3 FIG. FIG. 3 is a block diagram showing a space diversity controller according to an embodiment of the present invention. In FIG. 3, reference numerals 31 and 32 denote drive signals supplied from the D / A converters 10 and 11 to the phase shifter 16. Amplifying circuit for changing the voltage level of the voltage according to the ambient temperature, 31a
32a is a voltage amplifier, and 31b and 32b are thermal elements for voltage feedback.

Next, the operation will be described. Since the voltage-current characteristics of the diode change sensitively according to the ambient temperature,
As the ambient temperature rises, the DC impedance at the same voltage decreases and the current increases. In this case, the thermosensitive elements 31b and 32b whose resistance values decrease with the temperature rise are arranged in the feedback sections of the voltage amplifiers 31a and 32a, so that the thermosensitive elements 31b and 32b become the voltage amplifiers 31a and 32b.
The DC impedance is constant because it works to lower the output drive voltage a. On the other hand, when the ambient temperature decreases, the output voltage acts to increase, so that the DC impedance becomes constant. Since the DC impedance is constant in this way, even if the ambient temperature changes, the phase shifter 16
Are kept constant.

[0031]

As described above, according to the first aspect of the invention, sine wave and cosine wave data on which predetermined constants of positive polarity or negative polarity are preliminarily superimposed according to the phase are stored. Since the memory which outputs each waveform data from the address corresponding to the count value of the up / down counter is provided,
Since the amplitude of the composite vector that drops at a predetermined phase point is compensated by the predetermined constant, the composite vector of the phase shifter has a constant amplitude regardless of the phase change, and an effect such as obtaining a high control accuracy can be obtained. There is.

According to the second aspect of the present invention, since the resistor is connected in series between the digital-to-analog converter and the phase shifter, the current flowing through the diode of the balanced modulator can be maintained even when the ambient temperature changes. Since the phase shifter is constant, the combined vector of the phase shifter has a constant amplitude irrespective of a change in its phase, and has an effect such that a vector with high control accuracy can be obtained.

According to the third aspect of the present invention, since the digital / analog converter is provided with the voltage amplifying circuit for changing the voltage level of the drive signal supplied to the phase shifter in accordance with the ambient temperature, the balanced modulator is provided. Since the DC impedance of the diode becomes constant, the combined vector of the phase shifter has a constant amplitude irrespective of a change in the phase of the phase shifter.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a space diversity control apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a space diversity control device according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a space diversity control apparatus according to an embodiment of the present invention.

FIG. 4 is a waveform diagram showing a first drive signal and a second drive signal in FIG.

FIG. 5 is a characteristic diagram showing an amplitude characteristic of a combined vector of the phase shifter by the space diversity control device according to the first aspect of the present invention.

FIG. 6 is a characteristic diagram showing a voltage-current characteristic of a diode constituting the balanced modulator.

FIG. 7 is a characteristic diagram showing a variation of a combined vector on a phase plane when an ambient temperature changes.

FIG. 8 is a block diagram showing an example of an in-phase combined space diversity receiver to which the present invention and a conventional space diversity control device are applied.

FIG. 9 is a configuration diagram illustrating details of a phase shifter in the in-phase combining space diversity receiver.

FIG. 10 is a block diagram showing a conventional space diversity control device.

FIG. 11 is a waveform diagram showing a first drive signal and a second drive signal by a conventional space diversity control device.

FIG. 12 is a characteristic diagram showing a combined vector amplitude characteristic of a phase shifter by a conventional space diversity controller.

[Explanation of symbols]

 2 A / D converter (analog / digital converter) 3 Holding circuit 4 Comparison circuit 5 U / D counter (up / down counter) 10, 11 D / A converter 27, 28 ROM (memory) 29, 30 Resistor 31 , 32 Voltage amplifier circuit

Claims (3)

(57) [Claims] An analog-to-digital converter for digitally converting combined information of an in-phase combined space diversity receiver output from a detector, and a holding circuit for temporarily storing the combined information digitally converted by the analog-to-digital converter A comparison circuit that compares the current synthesis information digitally converted by the analog-to-digital converter with the synthesis information before a predetermined time temporarily stored in the holding circuit; and increases or decreases in accordance with the comparison result of the comparison circuit. An up-down counter that counts in a decreasing direction and waveform data of sine and cosine waves on which predetermined constants of positive polarity or negative polarity are preliminarily superimposed according to the phase are stored, and correspond to the count value of the up-down counter. A memory for outputting each waveform data from the obtained address and an analog conversion of each waveform data output from the memory. A space diversity control apparatus comprising: a digital-to-analog converter that supplies a drive signal to the phase shifter of the in-phase combined space diversity receiver in turn. 2. The space diversity control device according to claim 1, wherein a resistor is connected in series between said digital / analog converter and said phase shifter. 3. The space diversity according to claim 1, further comprising a voltage amplifying circuit for changing a voltage level of a drive signal supplied to said phase shifter by said digital / analog converter in accordance with an ambient temperature. Control device.