JPH05308307A - Superdiversity reception system - Google Patents

Abstract

PURPOSE:To prevent abnormal composition if a received local oscillation signal can not be received owing to the breakage, secular change, etc., of a high frequency cable connecting receiving devices as to the superdiversity reception system which is composed of >=2 receiving devices. CONSTITUTION:A detector 8 in a receiving device 13B detects the level of the received local oscillation signal inputted through the high-frequency cable 12A and outputs the detected voltage. A voltage comparator 15 compares the detected voltage with a reference voltage and controls the attenuation quantity of a power attenuator 14 according to the comparison result. Consequently, the receiving device 13B does not perform composing operation unless the received local oscillation signal is normally inputted to the receiving device 13B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined space diversity receiving system used in a microwave band radio communication device.

[0002]

2. Description of the Related Art As a conventional space diversity receiving system, there is a system shown in the block diagram of FIG.
As shown in FIG. 2, the receiving device 13A and the receiving device 13B are connected by high frequency cables 12A and 12B.
The receiving device 13A includes a receiving antenna ANT1 and a demultiplexing circuit 1
A, a high frequency power amplifier 2A, a combiner 3A, an intermediate frequency power amplifier 4A, and a receiving station oscillator frequency oscillator 5. The receiving device 13B includes a receiving antenna ANT2, a demultiplexing circuit 1B, a high frequency power amplifier 2B, a combiner 3B, an intermediate frequency power amplifier 4B, an infinite phase shifter 6, a high frequency variable gain amplifier 7, a wave detector 8 and a power distributor 9A. 9B, power combiner 1
0 and a phase detection and ESP control circuit 11.

The receiving station originating signal output from the receiving station originating frequency oscillator 5 in the receiving device 13A is a high frequency cable 12
It is input to the receiving device 13B via A. The receiving station signal is amplified by the high frequency variable gain amplifier 7 in the receiving device 13B by the amount of attenuation in the high frequency cable 12A,
It is set to a constant level and input to the infinite phase shifter 6. As a result, the conventional space diversity receiving system shares the signal from the receiving station.

[0004]

However, in the above-mentioned conventional space diversity receiving system, even when the signal originating from the receiving station cannot be received due to damage of the high frequency cable connecting between the receiving devices and deterioration over time, the noise is directly received. There is a problem in that the components are amplified and combined to cause signal deterioration.

The present invention has been made in view of the above problems, and in a space diversity receiving system composed of two or more receiving devices, the high-frequency cable connecting the receiving devices is damaged and deteriorated over time. By
An object of the present invention is to provide a space diversity receiving system capable of preventing abnormal synthesis when a certain receiving device cannot receive a signal originated from a receiving station.

[0006]

A space diversity receiving system according to the present invention is a space diversity receiving system having a plurality of receiving devices, from a receiving device having a receiving station originating frequency oscillator for generating a receiving station originating signal to a high frequency cable. A detector for detecting the receiving station-originated signal input via, a voltage comparator for comparing the detection voltage output by this detector with a reference voltage, and an attenuation amount controlled according to the output of this voltage comparator. And a power attenuator that operates.

[0007]

In the space diversity receiving system according to the present invention, in the space diversity receiving system composed of two or more receiving devices, the detector detects the level of the signal from the receiving station input via the high frequency cable. Output the detection voltage. The voltage comparator compares the detected voltage with a reference voltage and controls the attenuation amount of the power attenuator based on the comparison result. As a result, when the receiving station originating signal is not normally input to the receiving device, the input receiving station originating signal is blocked by the power attenuator and is not combined. Therefore, the space diversity receiving system according to the present invention performs abnormal synthesis when a certain receiving device becomes unable to receive a signal originated from a receiving station due to damage of a high-frequency cable connecting each receiving device or deterioration over time. It is possible to prevent that.

[0008]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a space diversity receiving system according to an embodiment of the present invention. In addition,
In FIG. 1, the same components as those of the conventional space diversity reception system shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

In the space diversity receiving system according to the embodiment shown in FIG. 1, the components different from the conventional space diversity receiving system shown in FIG.
3B is a part in which a power attenuator 14 and a voltage comparator 15 are added. The power attenuator 14 is provided between the power distributor 9B and the power combiner 10. The input end of the voltage comparator 15 is connected to the output end of the detector 8, and the output end of the voltage comparator 15 is connected to the control end of the power attenuator 14.

Next, the operation of the space diversity receiving system according to this embodiment configured as described above will be described.

The receiving station originating signal generated by the receiving station originating frequency oscillator 5 in the receiving apparatus 13A is input to the receiving apparatus 13B via the high frequency cable 12A. The level of the signal from the receiving station is detected by the wave detector 8 in the receiving device 13B. The detected voltage which is the output of the detector 8 is compared with a predetermined reference voltage in the voltage comparator 15 to determine whether or not the receiving station originating signal whose level has been detected in the detector 8 is at a normal level. Here, when it is determined that the reception station-originated signal is not at the normal level, it is determined that the reception station-originated signal is not normally input, and the amount of attenuation in the power attenuator 14 is determined by the output of the voltage comparator 15. To be maximized. When the amount of attenuation in the power attenuator 14 becomes maximum, the signal input to the power combiner 10 is only the signal that has passed through the high frequency cable 12B, so that the power combiner 10 does not combine power.

[0013]

As described above, according to the space diversity receiving system of the present invention, in the space diversity receiving system composed of two or more receiving devices, the input level of the signal from the receiving station is detected and used as a reference. Since the amount of attenuation of the power attenuator provided in the preceding stage of the power combiner is controlled based on the comparison result with the voltage, a certain receiving device may be damaged due to damage of the high frequency cable connecting between the receiving devices and deterioration over time. When it becomes impossible to receive the signal originating from the receiving station, it is possible to prevent abnormal synthesis, and it is possible to prevent deterioration of the signal due to the abnormal synthesis.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing an example of a conventional space diversity receiving system.

[Explanation of symbols]

 1A, 1B; Demultiplexing circuit 2A, 2B; High frequency power amplifier 4A, 4B; Intermediate frequency power amplifier 5; Receiving station oscillator frequency oscillator 8; Detector 10; Power combiner 12A, 12B; High frequency cable 13A, 13B; Receiving device 14; Power attenuator 15; Voltage comparator

Claims (1)

[Claims] 1. In a space diversity receiving system having a plurality of receiving devices, a detection device for detecting the receiving station-originated signal input via a high frequency cable from a receiving device having a receiving station-originated frequency oscillator for generating a receiving station-originated signal. Diversity, a voltage comparator for comparing a detection voltage output by the detector with a reference voltage, and a power attenuator for controlling an attenuation amount according to the output of the voltage comparator Receiving method.