JPS58197944A - Carrier regenerative system for 4-phase demodulator - Google Patents

Abstract

PURPOSE:To obtain the regenerative output of carrier with a simple construction and without complex adjustment, by utilizing two demodulated waves having orthogonal phases each other which can be outputted from two sets of phase detector. CONSTITUTION:An input signal supplied to a terminal 1 is branched by a signal distributor 2 and supplied to phase detectors 3 and 3' respectively. To the detectors 3 and 3', the outputs of an oscillator 8 for voltage control are supplied directly and also via a 90 deg. phase shifter 10 and then the input signals are demodulated to two signals orthogonal each other. These signals are discriminated as 1 or -1 by circuits 4 and 4' for demodulation discrimination. The outputs of detector 3 and circuit 4' and the outputs of the detector 3' and circuit 4 are multiplied by multipliers 5 and 5', and the output of the multiplier 5' is subtracted by the output of the multiplier 5 by a subtractor 6. The output of the subtractor 6 is supplied to the oscillator 8 as a signal for phase control via a loop filter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carrier wave recovery method for a four-set phase demodulator in wireless digital communications.

In general, in wireless f'' inotal communication, to reduce the error rate of signals demodulated on the receiving side.

A synchronous detection method is often used as a demodulator. In order to perform coherent detection, it is necessary to regenerate the carrier wave. Here, various examples as shown in FIG. 1 can be cited as conventional carrier wave regeneration methods applied to the four-set phase demodulator. In the figure, (a) shows a multiplication method, (b) shows an inverse modulation method, (C) a re-modulation method, and (d) shows a Co5tas (Costas) τso method. However, the multiplication method (a) requires a lot of man-hours to adjust the filter that selects the multiplication frequency, and the inverse modulation method (b) and remodulation method (C) both require the time required for the two inputs given to the modulator and detector. It is difficult to adjust the
The TAS loop method has the disadvantage of requiring an extra number of detectors.

The object of the present invention is to eliminate the drawbacks of the prior art mentioned above.

By making effective use of two sets of demodulated outputs.

It is an object of the present invention to provide a carrier wave regeneration method in a four-set phase post-adjustment device having a simple configuration and capable of obtaining a carrier wave regeneration output without requiring troublesome adjustment.

According to the present invention, the first and second phase detection means multiply two mutually orthogonal demodulated waves obtained from the outputs of the first and second phase detection means by the determination output obtained by intersecting each other. 2 multiplication means, and means for subtracting the multiplication value of one of the isothermal first and second multiplication means from the multiplication value of the other.

A carrier wave regeneration system in a four-phase phase demodulator is obtained, characterized in that the voltage controlled oscillation means is controlled by the output of the subtraction means to add a regenerated carrier wave to the first and second phase detection means.

Next, a carrier wave regeneration method of a four-phase demodulator according to the present invention will be described with reference to two embodiments and the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment according to the present invention. In this figure, 1 is a reception input terminal, 2 and 9 are signal distributors, 3.3' is a phase detector, and 4
．． 4' is a demodulation wave determination circuit, and 5.5' is a multiplier.

6 is a subtractor (or adder), and 7 is a loop filter.

8 is a voltage controlled oscillator, and 10 is a 90° phase shifter. In such a configuration, the received input signal applied to the input terminal 1 is branched by the signal splitter 2.

are applied to phase detectors 3 and 3', respectively. The phase detectors 3 and 3' are supplied with one of the oscillator outputs directly from the voltage controlled oscillator 8 via a distributor 9, and the other is supplied through a 90° phase shifter 10. The signal is demodulated into two local signals whose phases are orthogonal to each other. These demodulated signals are passed through demodulated wave determination circuits 4 and 4' to 1. or -1
It is determined that

The output of the phase detector 3 and the output of the demodulated wave determination circuit 4' are added to the multiplier 5, where the two outputs are multiplied by the multiplier 5'.
is added thereto, multiplied by the two human forces and applied to the other input of the subtractor 6. In the subtracter 6, the squaring multiplier 5'
The output of the multiplier 5 is subtracted from the output of the multiplier 5. This output is passed through a roots filter 7 and then given to a voltage controlled oscillator 8 as a phase control signal.

The phase control operation of this embodiment will be explained below.

Let's do a logical analysis. First, in Figure 2
, Zn is a real analog value, Zn is a real analog value, is represented by an imaginary analog value. Further, assuming that the outputs zn of the demodulated wave determining circuits 4 and 4' are 1 and -1 determination results for Zl and zrl, respectively, the two-phase detection value Pd is.

Pd−=z′n仝. -Zn仝J ・・・・・・(1)
becomes.

FIG. 3 shows a vector diagram in each quadrant of the four-phase phase in the normal state and when the phase is rotated by θ.

In this figure, A, B, C, and D indicate normal vector states, and A'+B', C', and D' indicate states when the phase is rotated by θ from the normal vector.

Also, the signal is determined if it is in the ■quadrant. =1. Total 1=L
■If it is in the quadrant, □--1, destination = 1, [If it is in the 1st quadrant, then □--1. =-1, all two = 1s, and if it is in the ■ quadrant, it is gold. −1゜仝′−−1. Further, FIG. 4 shows the values of Zn and z'n in each quadrant when the phase is rotated by θ from the normal value. Using these values, (1)
Examining the values in each quadrant outside Zn Zn Zn in the formula.

(1) In quadrant.

Wild. -2nA/)o, -(cos19+dnθ)ten(
In the quadrant ωSθ−5inθ)4=2dnθ(It).

I△ △l (:znznznZn -1(l) = (cos19
-slnθ)・(−1)−(−〇・(coso 10S stones, 1−鵠θ(to) quadrant.

rz;'n-”n”n”)@)-←t)・(coso+
-(-1)-(-1)-650-picture・←Lee(
In the quadrant.

CZnZB zng-=(1)” (CO5θ-
l-(osθ+sh+θ)(-1)=2sinθ, and all amounts are proportional to sinθ in any quadrant. Therefore, by using these equations, it can be determined whether phase detection by two-phase rotation is performed correctly, and by controlling the voltage-controlled oscillator based on this detected value, it is possible to reproduce the carrier wave correctly.

As is clear from the above description, according to the present invention, the phase control function of the voltage controlled oscillator can be applied to a four-phase demodulator by simply configuring it so that the above equation (1) can be satisfied. This allows for correct transportation and temporary regeneration.
Of course, it saves adjustment man-hours.

The effect of improving economic efficiency is significant.

FIG. 3 is a diagram showing examples of various methods of carrier wave regeneration applied to the system.

FIG. 2 is a block diagram showing the configuration of an embodiment according to the present invention;
FIG. 3 is a four-phase phase vector diagram for explaining the operation of the embodiment, and FIG. 4 is a diagram showing detected outputs obtained in each quadrant corresponding to rotational phases.

In the figure, 1 is an input signal terminal, 2 and 9 are signal distributors,
3.3' is a phase detector, 4.4' is a demodulation wave determination circuit.

5.5' is a multiplier, 6 is a subtractor (or adder), 7 is a loop filter, 8 is a voltage controlled oscillator, and 10 is a 90° phase shifter.

Figure 1 CD)<b) Figure 3 Figure 4

Claims (1)

[Claims] 1. Outputs of the first and second phase detection means. Two demodulated waves whose phases are orthogonal to each other obtained from the outputs of the first and second phase detection means are multiplied by judgment outputs obtained by intersecting each other. It is equipped with a multiplication means and a means for subtracting the multiplication value of the other J from the multiplication value of one of the isothermal 1 and second multiplication means, and controls the voltage controlled oscillation means by the output of the subtraction means to perform the above-mentioned 8fS1 and A carrier wave regeneration method in a four-set phase demodulation device characterized by the following: A regenerated carrier wave is added to a second phase detection means.