JPS60142630A - Compensating device of propagation distorsion - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention: fat Technical Field of the Invention The present invention relates to a propagation distortion compensation device, and particularly to a propagation distortion compensation device applied to multilevel digital wireless communication.

(bl Prior Art and Problems When performing high-efficiency multilevel digital wireless communication such as the 16-level quadrature amplitude modulation method or the 64-level quadrature amplitude modulation method using the microwave band, the state of the direct wave and the propagation path If interference waves generated by

Propagation distortion due to multipath fading occurring in such a transmission path is a cause of deterioration of line quality.

Figure 1 is a block connection diagram of a conventional propagation distortion compensator.
Figure 2 is a diagram of frequency characteristics to explain the operation of the block connection diagram in Figure 1. Figure 2 (a) is the frequency characteristic of the propagation path, Figure 2 (bl is the frequency of the propagation distortion FIG. 2(c) shows the characteristics and the equalization residual.

Therefore, the operation shown in FIG. 1 will be explained with reference to FIG. 2.

First, a digitally modulated wave with dips caused by multipath fading as shown in Figure 2+a) is input to a receiver (not shown), where it is amplified and frequency-converted before being converted into the wave shown in Figure 1. It is added to the propagation distortion compensator 9 shown in FIG.

This propagation distortion compensator 9 has a variable capacitor 3 and a wire ring 4 connected between the connection point between the series-connected amplifiers 1 and 5 and the ground.
A parallel resonant circuit consisting of Adjust to compensate for propagation distortion.

For this purpose, a part of the output signal of the amplifier 5 is applied to the spectrum detector 6 to detect the levels at both ends and the center frequency of the transmission band. Since a transmission line with no difference will have propagation distortion, the control section 8 creates a control signal to compensate for this difference.

Conventionally, this control unit 8 uses a microprocessor or the like. Then, using this control signal, the values of the variable resistor 2 and variable capacitor 3 are changed to adjust the characteristics as shown in FIG. 2 (bl).

However, with the compensation circuit in the frequency domain shown in Figure 1, it is difficult to estimate correctly from the reception spectrum due to the non-uniformity of the transmission spectrum, the finite nature of the spectrum monitor, etc. Due to reasons such as difficulty in setting the center frequency fo and sharpness Q of the circuit to optimal values, the equalization residual is large, as shown in Figure 2 tc+, and the line quality is not sufficiently improved. There was a problem.

(0) Purpose of the Invention The present invention was made in view of the problems of the prior art described above, and an object of the present invention is to provide a propagation distortion compensation method that does not deteriorate line quality even if multipath fading occurs in a propagation path. It is said that

fdl Structure of the Invention The object of the above invention is to provide a means for dividing a received signal given a delay amount corresponding to the path difference between a direct wave and an interference wave into first and second signals, means for respectively extracting in-phase data and quadrature data, an error voltage obtained from the in-phase data, and an error voltage obtained from the orthogonal data from the signal; and in-phase data delayed by a predetermined time and an error obtained from the in-phase data. An in-phase control signal and a quadrature control signal obtained by correlating the voltage and the error voltage obtained from the delayed in-phase data and the quadrature data, respectively, and the second signal are obtained by further dividing the second signal. and a means for adding the output of the mixing/synthesizing means to the received signal. This is achieved by providing a propagation distortion compensator characterized by the following.

Embodiment of the Invention FIG. 3 is a diagram of an equivalent circuit based on a two-wave model of fading.

In the figure, 12 is a circuit where the ratio of the amplitude of the direct wave and the interference wave is ρ, 13 is a circuit where the time difference between the propagation paths of the direct wave and the interference wave is τ, and 14 is a circuit that provides a phase difference φ. 10 and 1
1 indicates a hybrid circuit, respectively.

In FIG. 3, the input wave is separated by the hybrid circuit 10 into a direct wave with an amplitude of 1 passing through the path (2) and an interference wave with an amplitude of 1 passing through the path (2).

The direct wave continues as it is and is applied to the hybrid circuit 11. On the other hand, the interference wave that has proceeded along the path ■ undergoes changes such that the amplitude becomes ρ in the circuit 12, the time difference with the direct wave becomes τ in the circuit 13, and the phase difference becomes φ in the circuit 14, and then the interference wave is transferred to the hybrid circuit 11. The direct wave and the interference wave are added here and taken out as an output wave.

This output wave Y is shown as follows.

Here, the first term indicates a direct wave, and the second term indicates an interference wave.

Therefore, the transmission characteristic (ω) of this equivalent circuit is as follows.

This shows that if a circuit with completely opposite transmission characteristics is inserted into the receiver, it is possible to completely compensate for this fading characteristic and eliminate its influence.

Therefore, the transmission characteristic 11c(ω) of the propagation distortion compensator is expressed by the following equation.

As can be seen from equation (2), by changing ρ it is possible to compensate for the depth of the fading (dip), and by changing φ it is possible to compensate for the position of the dip.

Fig. 4 is a block connection diagram of a propagation distortion compensation circuit for explaining the present invention in detail, in which 15 and 18 are hybrid circuits, 16 is a delay circuit, and 17 is a part with variable attenuation and variable phase characteristics. be.

It is clear that the transmission characteristics of this device are expressed by equation (2).

FIG. 5 shows an example of a block connection diagram for implementing the present invention.

In the figure, 20 is a synthesis circuit, 21 is a delay circuit, and 22°2
3.26 and 32 are hybrid circuits, 24, 25,
29°30.33 and 34 are multiplication circuits, 27 and 28
is an integration circuit, 38 is an identification circuit, 31 is a 1-bit delay circuit, 35 and 36 are low-pass filters, 37 is a carrier recovery circuit, 40, 41 and 42 are terminals, and 50 is a demodulation circuit. , 51 represents an in-phase distortion control circuit, and 52 represents an orthogonal distortion control circuit.

These elements are connected as follows.

The terminal (1) of the hybrid circuit 26 is connected to the terminal 40 via the delay circuit 21 and the synthesis circuit 20, the terminal (2) is connected to the demodulation circuit 50, and the terminal (3) is connected to the in-phase control circuit 51 and the orthogonal control circuit 52. The synthesis circuit 20
are connected to each other.

Further, terminals (1) and (6) of the identification circuit 38 are connected to the demodulation circuit 50, terminal (2) is connected to the terminal 41, and terminal (3) is connected to the demodulation circuit 50, respectively.
is terminal 42, and terminal (4) is multiplier circuit 30. Integral circuit 2
8 to the in-phase control circuit 51, and the terminal (5) to the multiplier circuit 29.8. They are each connected to an orthogonal control circuit 52 via an integrating circuit 27.

Further, the terminal (2) of the delay circuit 31 is connected to the terminal 41 and the terminal f1.
) are connected to terminals (11) of multiplier circuits 29 and 30, respectively.

The operation of the circuit of FIG. 5 connected in this manner is as follows.

The digital modulated wave input to the terminal 40 is sent to the synthesis circuit 20
After passing through the delay circuit 21 and the delay circuit 21, the signal is divided into two by the hybrid circuit 26. Some signals are 90 degree hybrid circuit 2
After further division by 3, each signal is applied separately to multiplier circuits 24 and 25.

On the other hand, the remaining signal divided by the hybrid circuit 26 is applied to a known demodulation circuit 50, further divided into two by a hybrid circuit 32 included in this circuit, and each signal is applied to separate multiplication circuits 33 and 34. . These multiplier circuits 33 and 34 are synchronized with the carrier wave of the digital modulated wave inputted from the carrier wave regeneration circuit 37 and have a phase difference of 90 degrees.
Since different carrier waves are added, the two carrier waves and the digital modulation wave are multiplied here to obtain the in-phase and quadrature components of the demodulated signal. The in-phase and quadrature components of this demodulated signal pass through low-pass filters 35 and 36, respectively, and are applied to a known identification circuit 38, and the in-phase data and quadrature data reproduced from this identification circuit 38 are sent to terminals (2). as well as(
3) and the error voltages obtained from the in-phase data and quadrature data, respectively, are taken out from terminals (4) and (5), respectively.

Note that the error voltage is a voltage corresponding to a deviation from the correct signal level position.

Then, the in-phase data passed through the bit delay circuit 31 and delayed by 1 bit has a correlation between the error voltage Ei extracted from the in-phase data in the multiplication circuit 30 and the error voltage Eq extracted from the orthogonal data in the multiplication circuit 29. The obtained output voltages are respectively taken by the corresponding integrating circuits 28 and 2.
7 plus is integrated.

The outputs of the integrating circuits 28 and 27 are signals close to direct current (hereinafter referred to as in-phase control signals and quadrature control signals), and this in-phase control signal (referred to as a) is sent to the in-phase distortion control circuit 51 as a quadrature control signal (referred to as b). ) are applied to the multiplication circuits 24 and 25 included in the orthogonal distortion control circuit 52, respectively.

Here, the in-phase distortion and quadrature distortion control circuits 51 and 52 correspond to the variable attenuation/phase section 17 in FIG. 4.

0 Therefore, digital modulated waves having a phase difference of 90 degrees are applied to the multiplier circuits 24 and 25 as described above.
Now, for example, each of these digital modulated waves is 1・Cos
Let ω be and 1·Sinωt, and when this modulated wave is multiplied by the control signals a and b, respectively, two signals a-cosωt and bsinωt are obtained. This signal changes in the in-phase hybrid circuit 22, so its amplitude and phase change, but this composite wave is applied to the composite circuit 20 and combined with the digital modulated wave.

Since the section including the synthesis circuit 20, delay circuit 21, and in-phase and quadrature control circuits 51 and 52 has the same circuit configuration as that shown in FIG. 4, the propagation distortion generated in the propagation path is completely compensated for in this section. I can do that.

The delay circuit 21 has a delay amount corresponding to the average path length difference of the propagation paths in the two-wave model, and when the orthogonal control signal is set to 0, the center of the frequency characteristic on the input side of the multiplier circuit 24 is in the transmission band. Make fine adjustments to match the center frequency f.

In addition, the high print circuits 23 and 22 can be used in reverse, and the output signal can be taken not only from the output of the high print circuit I8 but also from any output of the variable attenuation/phase section 17 or the delay circuit 16. good.

As explained in 2.if) Effects of the Invention, according to the present invention, propagation distortion generated in a transmission path is compensated for using a propagation distortion compensator having characteristics inverse to fading characteristics in the time domain suitable for digital signals. Therefore, the compensation ability is high and compensation can be performed with high accuracy. Furthermore, compared to conventional methods that use a microprocessor or the like, the structure is simpler and control can be performed more stably, resulting in higher effects.

[Brief explanation of drawings]

Figure 1 shows a conventional example for compensating propagation distortion, and Figure 2 shows a conventional example for compensating propagation distortion.
FIG. 3 is a diagram showing an equivalent circuit of multipath fading, FIG. 4 is a diagram to explain the present invention in detail, and FIG. An example of a propagation distortion compensator using the following is shown below. In the figure, 20 is a synthesis circuit, 21 and 31 are delay circuits,
22.23 and 26 are hybrid circuits, 24, 2
5, 29 and 30 are multiplication circuits, and 27 and 28 are integration circuits, respectively. 3 2 Dormitory I factor η Mine 2 [1iJ ((1, (b) (α)

Claims (1)

[Claims] means for dividing a received signal given a delay amount corresponding to the path difference between the direct wave and the interference wave into first and second signals; and means for dividing in-phase data, quadrature data and means for respectively extracting the error voltage obtained from the in-phase data and the error voltage obtained from the orthogonal data; and the in-phase data delayed by a predetermined time, the error voltage obtained from the in-phase data, and the delayed in-phase data. An in-phase control signal and a quadrature control signal obtained by correlating with the error voltage obtained from the orthogonal data, and a third signal and a fourth signal obtained by further dividing the second signal. 1. A propagation distortion compensator comprising a mixing/synthesizing means for mixing and synthesizing the signals of the above signals using an in-phase control circuit and an orthogonal control circuit, respectively, and means for adding an output of the mixing/synthesizing means to the received signal.