JPS6333334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for preventing reception of interference waves in a wireless communication system when the desired wave reception input suddenly decreases.

[Conventional technology]

In general, in wireless communication systems, the desired signal level D is usually sufficiently large compared to the interference wave level U, so the total line noise amount is evaluated by the desired signal-to-interference ratio (D/U), and the required signal-to-noise ratio (S /N).

[Problem to be solved by the invention] In such a design, if the interference wave level U is higher than the threshold level of the receiving device, the interference wave will be received when the desired wave is cut off. There were flaws.

In order to solve these drawbacks, the present invention detects a sudden change in the received electric field of the desired wave and opens and closes the reception output, and when the desired wave is cut off, the signal path is closed and the interference wave is received. It is designed to automatically prevent this from happening.

EMBODIMENT OF THE INVENTION Hereinafter, the structure etc. of this invention will be described in detail based on the drawing of an Example.

〔Example〕

FIG. 1 is a block diagram of a receiving apparatus according to an embodiment of the present invention, in which 1 is a receiving high frequency section, 2 is an intermediate frequency amplifier, 3 is a demodulator, 4 is a received signal opening/closing switch, and 5 is a received signal level. 6 is a switch control circuit for controlling opening/closing of a receiving signal opening/closing switch based on the output of the differentiating circuit, and 7 is a receiving input level monitor terminal.

In FIG. 1, a signal taken out from a reception input level monitor terminal 7 of an intermediate frequency amplifier 2 is input to a differentiating circuit 5. The differentiation circuit 5 outputs a constant signal only when a sudden change in the level of the signal is detected (when the differential value reaches a constant value). The switch control circuit 6 controls the opening and closing of the reception signal opening/closing switch 4 based on the output signal of the differentiating circuit 5.

FIG. 2 is a diagram showing the level changes of each part in FIG. 1, where 8 represents the temporal change in the output level at the receiving input level monitor terminal, and 9 and 9' represent the output signals of the differentiating circuit.

When the received electric field decreases due to normal rain attenuation, the change is gradual, but when the other party's transmitting device malfunctions, the received input decreases rapidly. In such a case, there is a possibility that interference waves may be received. The system of the present invention has the characteristic of selectively operating only when there is a possibility of receiving interference waves by detecting a sudden drop in the reception level using a differentiating circuit.

In addition, when the other party's transmitter recovers from a failure, etc., the reception input increases rapidly, but at this time,
Since the direction of the temporal change in the signal level at the reception input level monitor terminal is opposite to that in the case of a decrease in reception input, the output of the differentiating circuit becomes as shown at 9' in FIG.

That is, the polarity differs when the received input level decreases and increases. The switch control circuit 6 determines this difference in polarity and controls the received signal on/off switch 4 to automatically restore the line.

Although Fig. 1 shows the case where the received signal on/off switch 4 is installed after the demodulator 3, the purpose of this switch is to open/close the received signal, and its installation position is not necessarily after the demodulator. It's fine even if you don't have it.

〔Effect of the invention〕

As explained above, the method of the present invention detects a sudden drop in the reception input level and immediately disconnects the reception circuit to stop outputting the signal.
Since the system detects the subsequent rapid rise in the reception input level and demodulates the reception circuit, it can be used selectively in the event that conditions occur that may cause interference waves to be received due to a malfunction in the other party's transmitter. This has the advantage of being able to operate and prevent reception of interference waves.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a receiving apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing level changes in various parts of the circuit shown in FIG. 1. 1... Receiving high frequency section, 2... Intermediate frequency amplifier,
3... Demodulator, 4... Reception signal open/close switch, 5
...Differential circuit, 6...Switch control circuit, 7...
Reception input level monitor terminal, 8... Temporal change in output level at the reception input level monitor terminal;
9, 9'... Output signal of the differentiator circuit.

Claims (1)

[Claims] 1. A radio receiving device is provided with means for detecting a level change in the received input and obtaining its differential value, and means for controlling whether or not to output a signal as a result of processing the received input. When the differential value of the level change exceeds a predetermined constant value, the output signal of the receiving device is stopped, and after that, the differential value of the level change due to an increase in the receiving input exceeds a predetermined constant value. An interference wave reception prevention method characterized by restarting transmission of an output signal from a receiving device when interference wave reception is exceeded.