JPS60254841A - Phasing equalization system - Google Patents

Abstract

PURPOSE:To cancel interference wave signals completely by allowing a space diversity radio receiver to perform AGC over a main and a subordinate side intermediate frequency amplifier with a higher level between their detection outputs. CONSTITUTION:When the output level of a main side detector 9 is higher than the output level of a subordinate side detector 19, the current of a transistor TrT-1 is smaller than that of a TrT-2, and then the potential at a point (a) rises above the potential at a point (b) and the voltage across a resistance R1 equals the potential at the point (a). This voltage is amplified by a DC amplifier 24 and supplied to variable attenuators 3 and 13 to perform AGC operation, and circuits of an antenna 1 (main side) and an antenna 11 (subordinate side) become equal in gain. Therefore, main wave signals and interference signals inputted to the antennas 1 and 11 are amplified with the same gain, and the phases of the interference wave signals are adjusted by an infinite phase shifter 21 so that they cancel each other, thereby canceling the interference waves completely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a fading equalization method for a space diversity radio receiving device.

In radio receiving devices, multipath fading that occurs in the propagation path causes deterioration of line quality.

To prevent this, a space diversity method is used, but it is desirable to sufficiently compensate for the deterioration in line quality due to facing.

[Conventional technology]

FIG. 2 is a block diagram of the main parts of a conventional space-diaperity type microwave radio receiving apparatus.

In FIG. 2, the signal received by antenna 1 is transmitted to low noise amplifier 2. Variable attenuator 3. Low noise amplifier 4, microwave band pass filter 5. The signal is inputted to the mixer 6 via the converter, is converted into an intermediate frequency band, and passes through intermediate frequency amplifiers 7 and 8 to the hybrid 22.

On the other hand, the signal received by the antenna 11 is transmitted to the low noise amplifier 12.
．． Variable attenuator 13. Low noise amplifier 14° microwave band'pass filter 15. is input to the mixer 16 via
8. The signal passes through the infinite phase shifter 21 and reaches the hybrid 22, where it is combined with the signal received on the antenna 1 side and output to the next stage.

In this case, the outputs of the intermediate frequency amplifiers 7, 17 are transmitted to the detector 9.
] Detected at 9 and amplified at DC amplifier 10.20,
Input to variable attenuator 3.13, intermediate frequency amplifier 7,1
Each AGC operation is performed so as to shift the output level of 7 to a constant value, so that the intermediate frequency amplifiers 8 and 18 are not overloaded, and the intermediate frequency amplifiers 8 and 18 can perform distortion-free amplification.

Now, on the antenna 1 side, there is a main wave signal E as shown in Fig. 3 (A).
1 and the interference wave signal E2 due to multipath fading are input, and the main wave signal E3 and the interference wave signal E4 due to multipath fading are input to the antenna 2 side as shown in FIG. 3(B).
is input (in this case, since the antennas 1 and 11 are installed close to each other, the absolute values of the main wave signals E1 and R3 are equal, and the absolute values of the interference wave signals E2 and R4 are equal), the infinite phase shifter 21 becomes Controlled by a control circuit (not shown), the phase of the interference wave signal E4 is made to be 180 degrees different from the phase of the interference wave signal E2, as shown in FIG. 3(C),
Fading equalization is performed so as not to reduce the amplitude deviation by causing the main wave signals El and E3 to cancel each other at the output of the hybrid 22 to obtain a signal E5 that is a composite of the main wave signals El and E3.

Note that 23 is a local oscillator.

[Problem that the invention seeks to solve]

However, the absolute value of the composite wave signal E6 of the main wave signal E1 and interference wave signal E2 input to the antenna 1 side is the absolute value of the composite wave signal E7 of the main wave signal E3 and interference wave signal E4 input to the antenna 11 side. Even if it is smaller, in the case of Figure 2 A
Due to the GC operation, the absolute values of the composite wave signals become equal at the output of the intermediate frequency amplifier 7.17.

This means that the main wave signal E3 and interference wave signal E4 input to the antenna 11 side have a smaller amplification degree than the main wave signal E1 and interference wave signal E2 input to the antenna 1 side, so the intermediate frequency amplifier 7. Looking at the output of 17, the interference wave signal E
The absolute value of 4 is smaller than the absolute value of the interference wave signal E2,
Even if the phase is changed by 180 degrees to cancel out the difference, there is a problem that it cannot be completely canceled.

[Means for solving problems]

The above problem can be solved by the fading equalization method of the present invention, in which the detection output of the intermediate frequency amplifiers on the main side and the sub side each has a higher level and is fed back to the main side and the sub side to perform automatic gain control. It is solved by

[Effect]

In the present invention, the higher level detection output of the intermediate frequency amplifiers on the main and sub sides is fed back to the main and sub sides to perform AGC operation, so the common gains on the main and sub sides are the same, and the main and sub sides have the same gain. Both the main wave signal and the interference wave signal input to the side are amplified with the same gain, so if the phase of the interference wave signal on the side is set to be 180 degrees different from the phase of the main side interference wave signal to cancel them out. , can be completely canceled out.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the main parts of a space-diaperity type microwave radio receiving apparatus according to an embodiment of the present invention.

In the figure, 24 is a DC amplifier, R1 is a resistor, R2 and R3 are resistors of the same value, TI and T2 are transistors, Di and R2 are diodes, and ■ is a power supply voltage. Throughout the figure, the same symbol indicates the same function. show something

The outputs are input to transistors TI and T2, respectively, and resistor R1
The point is that the voltage across both ends of the signal is amplified by the DC amplifier 24, and AGC is performed in addition to the variable attenuator 3.13.

In this way, for example, if the output voltage of the detector 9 is higher than the output voltage of the detector 19, the current flowing through the transistor Tl will be smaller than the current flowing through the transistor T2, and the voltage at point A will be lower than the voltage at the four points. is also high, the voltage across the resistor R1 becomes the voltage at point A, and this voltage is applied to the DC amplifier 24.
The signal is amplified and supplied to the variable attenuators 3 and 13 to perform AGC operation, and the gains of the circuits on the antenna 1 side (main side) and the antenna 11 side (secondary side) are the same.

Therefore, the main wave signal El shown in FIGS. 3(A) and 3(B) is input to the antenna 1 side and the antenna 11 side.

Interference wave signal E2 and main wave signal E3. Since the interference wave signal E4 is amplified with the same gain, it can be completely canceled by canceling the interference wave signal as shown in FIG. 3(C).

Furthermore, since the AGC operation is performed by changing the output level of the intermediate frequency amplifier 7 or 17, the intermediate frequency amplifiers 8 and 18 will not be overloaded, and the above operation can be performed completely. can be canceled out.

〔Effect of the invention〕

As explained in detail above, according to the present invention, it is possible to completely cancel interference wave signals for fading equalization.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of a space diversity type microwave radio receiving apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of the main parts of a conventional space diversity type microwave radio receiving apparatus. FIG. 3 is a vector diagram of the main wave signal and the interference wave signal. In the figure, 1.11 is an antenna, 2.12, 4.14 are low noise amplifiers, 3.13 is a variable attenuator, 5.15 is a microwave bandpass filter, and 6.16
is a mixer, 7.17-. 8.18 is an intermediate frequency amplifier, 9.19 is a detector, 10.20.24 is a DC amplifier, 21 is an infinite phase shifter, 22 is a hybrid, 23 is a local oscillator, R1, R2, R3 are resistors, TI, T2 is a transistor, and Dl and D2 are diodes. Rod 3 diagram A) \\ E2 (C)

Claims (1)

[Claims] In a space-diaperity wireless receiving device,
A fading equalization method characterized in that the detection output of the intermediate frequency amplifiers on the main side and the sub side, whichever has a higher level, is fed back to the main side and the sub side to perform automatic gain control.