JPS6352527A - Selective call method - Google Patents

Abstract

PURPOSE:To prevent radio wave jack by a malicious 3rd party by sending a selective call signal and a different code at each transmission of the selective call signal from a base station to a terminal station and allowing the terminal station to make a call from the base station effective when both the selection signal and the code are correct. CONSTITUTION:When a terminal station (x) is selected by a selection control section 10 in a base station (y), a call signal generating section 11 generates a call signal of the selected terminal station (x), a code generating section 12 generates a code different at each transmission of the call signal, a synthesis section 13 synthesizes the call signal and the code and a transmission section 14 sends a synthesized signal F0. On the other hand, when a reception section 15 of the selected terminal station (x) receives the signal F0, a call signal check section 16 detects the call signal in the signal F0 and sends the code in the signal F0 to a code coincidence check circuit 18 when the call signal is correct. Moreover, a code generating circuit 17 generates a code, the code coincidence check section 18 identifies the code with the code in the signal F0 and starts an amplifier 19 when the code is correct. In this case, the code generating section 17 generates the same code as the code of the code generating section 12 of the basic station (y) and different at each reception of the call signal asynchronously.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a selective calling method, and more particularly to a selective calling method used in municipal disaster prevention administrative radio systems and the like.

2. Description of the Related Art In general, calls in a municipal disaster prevention administrative radio system are performed by a base station Y selectively transmitting a call signal F1 to a terminal station X, as shown in FIG.

Conventionally, in this type of selective calling, as shown in FIG. 3, when a terminal station A signal Fl is generated, and the transmitter 3 transmits a paging signal F1 to the selected terminal station.

On the other hand, in the selected terminal station
When the paging signal F1 is received, the paging signal detecting section 5 tests the paging signal F1, and if the paging signal F1 is correct, the amplifier 6 amplifies the signal from the base station Y, and the speaker 7 converts it into voice.

Problems to be Solved by the Invention However, in such a configuration, a malicious third party monitors the calling signal from the base station, records it on a tape recorder, etc., and plays it back at the same radio frequency, thereby making it possible to access the terminal station. It becomes possible to easily make a call, and the radio waves of the terminal station are jacked, which causes a big social problem.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a selective calling method that can prevent radio wave jacking of terminal stations.

Means for Solving the Problems In order to solve the above problems, the base station of the present invention transmits to the terminal station a selective paging signal and a code that is different each time the selective paging signal is sent, and the terminal station transmits the selective paging signal. The present invention is characterized in that the call from the base station is enabled when both the selection signal and the code are correct.

Effect: With the above configuration, the present invention prevents the terminal station from being called even if a malicious third party records a signal from the base station and calls the terminal station on the same frequency, thus preventing radio wave jacking. .

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic block diagram showing an embodiment of the municipal disaster prevention administrative wireless system according to the present invention.

The base station y includes a selection control unit 10 through which a terminal station X is selected by the operator, a paging signal generation unit 11 which generates a paging signal for the terminal station a code generator 12 that automatically counts pulses and generates a code with a different value each time a call signal is sent; and a synthesizer 13 that combines the call signal from the call signal generator 11 and the code from the code generator 12. The transmitter 14 is generally configured to send a signal to the terminal station X.

The terminal station X has a receiving unit 15 that receives a signal from the base station y.
, a paging signal verification unit 16 that verifies the paging signal from base station y; a code generating unit 12 of base station y;
A code generation section 17 that generates the same code as the code of , and a code coincidence test that tests whether the code from the base station y via the paging signal verification section 16 and the code from the code generation section 17 match. an amplifier 19 that is activated by the sign matching verification unit 18 and amplifies the signal from the base station y;
It is generally composed of a speaker 20 that reproduces the signal from the amplifier 19 into audio.

Next, the operation of the embodiment according to the above configuration will be explained.

When terminal station X is selected via selection control unit 10 in base station y, paging signal generation unit 11 selects terminal station
At the same time, the code generator 12 generates a code. In this case, the code generator 12 generates a different code each time the calling signal is sent.

Next, the combining section 13 combines the calling signal from the calling signal generating section 11 and the code from the code generating section 12, and the transmitting section 14 transmits the combined signal Fo to the selected terminal station.

On the other hand, in the selected terminal station
The calling signal in the signal Fo is verified, and if the calling signal is correct, the code in the signal Fo is sent to the code matching test circuit 18.

Further, the code generation circuit 17 generates a code, the code matching verification unit 18 identifies this code and the code in the signal Fo, and if the code is correct, starts the amplifier 19, and the amplifier 19
The signal is amplified and converted into audio by Subi Power 20. In this case, the code generator 17 asynchronously generates a code that is different each time a paging signal is received and is the same as the code of the code generator 12 of the switched base station y.

Therefore, even if a malicious third party records the signal sent from base station y with a tape recorder or the like and plays it back at the same frequency FO to send out a calling signal for terminal station X, the codes do not match and the terminal The amplifier 19 of station X is not turned on, and terminal station X is not jacked.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a base station transmits a selective paging signal and a different code each time the selective paging signal is transmitted to a terminal station, and the terminal station transmits both the selection signal and the code. Since calls from the base station are enabled in the correct case, even if a malicious third party records the signal from the base station and calls the terminal station on the same frequency, the terminal station will not be called. ,
Therefore, radio wave jacking can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of a municipal disaster prevention administrative radio system using the selective calling method according to the present invention;
FIG. 2 is a schematic configuration diagram of a general municipal disaster prevention radio system, and FIG. 3 is a schematic block diagram showing a conventional example. X: Terminal station, y: Base station, 11: Calling signal generation section, 12: Code generation section, 13: Combining section, 1
6... Calling signal verification section, 17... Code generation section, 18
・−・Sign-matching test section. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
7

Claims (1)

[Claims] The base station transmits to the terminal station a selective paging signal that calls the terminal station, and a code that is different each time the selective paging signal is sent,
Selective calling characterized in that a terminal station verifies the selective calling signal from the base station and also verifies the code, and validates the calling from the base station when both the selective calling signal and the code are correct. Method.