JPH10285655A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a wiretap in the case of conducting radio communication requiring security by sending a designation signal of a security code to a radio equipment from a base station via a connected wired line. SOLUTION: A clock 36 of a base station 24 measures a prescribed time a day and the clock 36 gives a random number generating instruction signal to a random number generating section 35 for the prescribed time. The random number generating section 35 receiving the random number generating instruction signal provides an output of a random number signal at the point of reception and the random number signal is sent to a security code storage section 34 of the base station 24 and sent also to a security code storage section 47 via an interface 37, a connector 38, a wired line 50, a connector 49 and an interface 48. Then the security code storage sections 34, 47 select a security code corresponding to the random number and provides an output of the code to digital MODEMs 30, 43. Thus, modulation/demodulation is attained between the base station and the terminal according to the coincident security code.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system for performing radio communication using a base station radio and a plurality of portable radios, and more particularly to preventing eavesdropping when performing radio communication requiring secrecy. The present invention relates to a wireless communication system capable of performing the following.

[0002]

2. Description of the Related Art In general, a radio communication system for performing radio communication using a base station radio and a plurality of portable radios is known. In the case of a radio communication system requiring confidentiality such as a police radio or a SDF radio, etc. And a plurality of secret talk patterns, which are switched by a dip switch or the like of the wireless device main body, so that a call can be made only when the secret code of the plurality of wireless devices is the same. FIG. 4 is a configuration diagram of a conventional wireless communication system in which a plurality of secret patterns as described above are switched by a dip switch. In FIG. 4, only one portable wireless device (terminal) is illustrated for one base station, and other terminals are omitted. As shown in FIG. 4, the wireless communication system includes a base station 1 for performing wireless communication and a portable wireless device (terminal) 2. The base station 1 includes a microphone 3 for inputting voice and a microphone 3 A / connected to
A D converter 4, a speaker 5 for outputting sound, a D / A converter 6 connected to the speaker 5, and a digital modem connected to the A / D converter 4 and the D / A converter 6. A transmitter 7, a transmitter 8 connected to the digital modem 7, an antenna 9 connected to the transmitter 8, and a receiver 10 connected to the antenna 9 and the digital modem 7. It has a secret code storage section 11 connected to the digital modulator / demodulator 7 and a dip switch 12 connected to the secret code storage section 11.

[0005] The terminal 2 also includes a microphone 13 for inputting voice and an A / D converter 1 connected to the microphone 13.
4, a speaker 15 for outputting sound, and the speaker 1
5, a D / A converter 16 connected to the A / D converter 14, the D / A converter 16, a digital modem 17 connected to the D / A converter 16, and a transmission unit 18 connected to the digital modem 17. , An antenna 19 connected to the transmitting unit 18, the antenna 19 and the digital modem 17
And a secret code storage unit 21 connected to the digital modulator / demodulator 17;
And a dip switch 22 connected to the secret code storage unit 21. The secret code storage units 11 and 21 are each composed of a memory such as a ROM, and store the same plurality of secret codes, and store secret codes corresponding to the set values of the dip switches 12 and 22 that can be switched. The signals are output to the digital modulators and demodulators 7 and 17.

Next, the operation will be described. First, the dip switches 12 and 22 are switched so that their set values are made to match in advance, and the secret code storage units 11 and 2 are switched.
The same secret code is supplied from 1 to each of the digital modulators and demodulators 7 and 17. Then, when performing wireless communication from the base station 1 to the terminal 2, the base station 1
The audio signal input from the microphone 3 is converted into a digital signal by the A / D converter 4, and the digital signal is scrambled (modulated) by the digital modulator / demodulator 7 in accordance with the secret code. And transmitted from the antenna 9 to the terminal 2 as a radio signal. The radio signal from the base station 1 is received by the antenna 19 and the receiving unit 20 of the terminal 2, and the received signal is descrambled (demodulated) by the digital modulator / demodulator 17 using the same secret code as the base station 1. ) And output as audio via the D / A converter 16 and the speaker 15. Similarly, when wireless communication is performed from the terminal 2 to the base station 1, the operation is the reverse of the above-described wireless communication from the base station 1 to the terminal 2. That is, the audio signal input from the microphone 13 of the terminal 2 is converted into a digital signal by the A / D converter 14,
The digital signal is scrambled (modulated) by the digital modulator / demodulator 17 in accordance with the secret code, and is transmitted to the base station 1 as a radio signal from the transmission unit 18 and the antenna 19. Then, the radio signal from the terminal 2 is received by the antenna 9 and the receiving unit 10 of the base station 1, and the received signal is descrambled (demodulated) by the digital modulator / demodulator 7 using the same secret code as the terminal 2. Then, it is output as sound via the D / A converter 6 and the speaker 5.

[0005]

However, in the above-described conventional wireless communication system, when the portable wireless device (terminal) 2 is stolen, for example, the stolen terminal 2
There is a possibility that the conversation may be eavesdropped by switching the dip switch 22. That is, when the terminal 2 is stolen, the base station 1 and the remaining terminal 2 use the dip switches 12, 22 to prevent eavesdropping.
, And the confidential code is changed to another confidential code, if the dip switch 21 of the stolen terminal 2 is changed in various ways, the confidential code may reach the changed confidential code. There is also a method of preventing eavesdropping by increasing the number of the confidential code, but eavesdropping is possible if the time is taken only by reducing the probability of hitting the changed confidential code. For example, specifically, when an 8-digit binary dip switch is used, only 28 = 256 secret codes can be handled, and the possibility of eavesdropping is high. The present invention has been made in view of the above circumstances, and has as its object to provide a wireless communication system capable of preventing eavesdropping when performing wireless communication requiring secrecy.

[0006]

In order to achieve the above object, the present invention provides a radio communication system for performing radio communication by unifying a secret code between a base station and a plurality of radios. The base station and the wireless device are connected by wire, and a designated signal of a secret code is supplied from the base station to the wireless device via the wire. Another feature of the present invention is that a wire connected to the base station is connected to the wireless device via a charger of the wireless device. Another feature of the present invention is that the base station generates a random number as a designation signal of the secret code at a predetermined time, a plurality of secret codes stored therein, and a secret corresponding to the generated random number. A secret code storage means for outputting a code, and a modulation / demodulation means for performing modulation / demodulation in accordance with the secret code, wherein the wireless device stores a plurality of secret codes and sends a random number transmitted from the base station via a wire. And a modulation / demodulation means for performing modulation / demodulation according to the secret code.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on illustrated embodiments. FIG. 1 is an overall view of a wireless communication system according to an embodiment of the present invention, and FIG. 2 is a block diagram of the base station and the portable wireless device (terminal) shown in FIG. First, as shown in FIG. 1, the wireless communication system has a configuration in which a plurality of portable wireless devices (terminals) 25 are provided for one base station 24. And FIG.
As shown in the figure, the base station 24 includes a microphone 26 for inputting sound, and an A / D converter 27 connected to the microphone 26.
And a speaker 28 for outputting sound, and the speaker 28
A / D converter 29 connected to the A / D converter 2
7, a digital modulator / demodulator 30 connected to the D / A converter 29, a transmitter 31 connected to the digital modulator / demodulator 30, and an antenna 3 connected to the transmitter 31
2, a receiving unit 33 connected to the antenna 32 and the digital modem 30, and a secret code storage unit 34 connected to the digital modem 30 and a random number connected to the secret code storage unit 34. Generator 35
A clock 36 connected to the random number generator 35, an interface 37 connected to the random number generator 35,
A connector 38 connected to the interface 37;
And 1.

[0008] The portable wireless device (terminal) 25 includes:
A microphone 39 for inputting audio, an A / D converter 40 connected to the microphone 39, and a speaker 41 for outputting audio
And a D / A converter 42 connected to the speaker 41
And the A / D converter 40 and the D / A converter 42
, A transmitting unit 44 connected to the digital modem 43, and a transmitting unit 44 connected to the digital modem 43.
, A receiving section 46 connected to the antenna 45 and the digital modulator / demodulator 43, and a secret code storage 47 connected to the digital modem 43; It has an interface 48 connected to the unit 47 and a connector 49-1 connected to the interface 48.
The connector 38-2 connectable to the connector 38-1 of the base station 24 and the connector 49-1 of the terminal 25
The connectable connector 49-2 is connected by a wire 50. In this embodiment, as shown in FIG.
The connector 49-1 of the terminal 25 is detachably connected to the cable 50 via a connector 49-2 on the inner bottom surface of the charger 51, and is connected to the connector 38-1 of the base station 24. The connector 38-2 and the wire 50 are directly connected. That is, usually, the terminal 25 is attached to the charger 51 at least once a day to perform charging, so that the terminal 25 is connected to the cable 50 via the charger 51 once a day. Are connected.
The secret code storage units 34 and 47 are each composed of a memory such as a ROM, and store the same plurality of secret codes, respectively. Output to the devices 30 and 43.

Next, the operation of the wireless communication system having the above configuration will be described. First, the operation of setting the secret code will be described. The base station 24 measures a predetermined time every day by the clock 36, and supplies a random number generation instruction signal to the random number generator 35 from the clock 36 at the predetermined time. Is done. The random number generation unit 35 that has received the random number generation instruction signal outputs a random number signal at the time of the input,
The random number signal is stored in the secret code storage unit 3 of the base station 24.
4 as well as to the secret code storage 47 of the terminal 25 via the interface 37, the connector 38, the wire 50, the connector 49 and the interface 48. Each of the secret code storage units 34 and 47 selects a secret code corresponding to the random number and outputs the selected code to each of the digital modulators and demodulators 30 and 43. Therefore, modulation and demodulation with the secret code coincident between the base station and the terminal are achieved.

Next, a communication operation in the wireless communication system will be described. The terminal 2 from the base station 24
5 when performing wireless communication, the microphone 26 of the base station 24 is used.
The input audio signal is converted into a digital signal by the A / D converter 27, and the digital signal is scrambled (modulated) by the digital modulator / demodulator 30 in accordance with the secret code, and the transmission unit 31 and the antenna 32 Is transmitted to the terminal 25 as a radio signal. The radio signal from the base station 24 is received by the antenna 45 and the receiving unit 46 of the terminal 25, and the received signal is descrambled (demodulated) by the digital modulator / demodulator 43 using the same secret code as the base station 24. ), The D / A converter 42 and the speaker 4
1 is output as voice. Next, the terminal 25
When performing wireless communication from the terminal 25 to the base station 24, the terminal 25
The audio signal input from the microphone 39 is converted into a digital signal by the A / D converter 40, and the digital signal is scrambled (modulated) by the digital modulator / demodulator 43 in accordance with the secret code.
4 and the base station 2 as a radio signal from the antenna 45.
4 is transmitted. Then, the radio signal from the terminal 25 is received by the antenna 32 and the receiving unit 33 of the base station 24, and the received signal is descrambled (demodulated) by the digital modem 30 using the same secret code as the terminal 25. The audio is output as audio through the D / A converter 29 and the speaker 28.

As described above, according to the present embodiment, the random number signal for setting the secret code is sent to the base station and each terminal by wire, and the secret code is set. There is no need to provide a switch, and there is no need to worry about eavesdropping in case of theft. When the secret code is changed when the date changes (midnight), when the terminal is used across midnight, the random number information from the base station is received after 0:00. Wireless communication becomes impossible. Therefore, the random number information transmitted from the base station may be transmitted for two days for the day and the next day.

In the above embodiment, the secret code is selected based on the random number. However, the random number may be directly used as the secret code. Further, a configuration may be adopted in which a large number of confidential code prepared in advance are selected sequentially or randomly without using a random number generator. In addition, a different secret code can be used for each terminal station, and the code can be easily managed on the base station side. As a result, confidentiality can be enhanced between terminals, and even if one terminal is stolen, conversations with other terminals cannot be intercepted.
Further, in this embodiment, the wired connection is made via the charger. However, the present invention is not limited to this, and a connector may be provided in a microphone holder for mounting a microphone, and the wired connection may be made. In the above-described embodiment, the timing of generating a random number is set by a clock. However, a setting switch may be provided, and the timing may be set by pressing the setting switch.

[0013]

As described above, according to the present invention, a random number signal for setting a confidential code is transmitted to the base station and each terminal by wire to set the confidential code. This eliminates the need to change the code of the stolen radio even if it is stolen without knowing the format of the serial signal. Therefore, if the code of another wireless device is changed, there is no risk of eavesdropping. That is,
Even if a stolen wireless device is nearby, it cannot receive a code setting signal unless it is connected with a wired serial signal, and it cannot be eavesdropped because it cannot be the same code as other wireless devices . Further, since the code setting does not depend on the switch, many combinations can be used without being limited by the number of digits of the switch.

[Brief description of the drawings]

FIG. 1 is an overall view of an embodiment of a wireless communication system according to the present invention.

FIG. 2 is a diagram illustrating a base station and a configuration wireless device (terminal) illustrated in FIG. 1;
FIG. 3 is a block diagram of the configuration of FIG.

FIG. 3 is an explanatory diagram illustrating a wired connection state in the wireless communication system illustrated in FIG. 2;

FIG. 4 is a block diagram of a conventional wireless communication system.

[Explanation of symbols]

1, 24 ... base station, 2, 25 ...
Terminals, 3, 13, 26, 39 ... microphones, 4, 14, 2
7, 40 ... A / D converter, 5, 15, 28, 41 ... speaker, 6, 16, 29, 42 ... D / A converter, 7, 1
7, 30, 43 ... Digital modulator / demodulator, 8, 18, 31,
44 ... transmitting unit, 9, 19, 32, 45 ... antenna, 1
0, 20, 33, 46... Receiving unit, 11, 21, 34, 4
7 ... Secret talk code storage unit, 12, 22 ... Dip switch, 35 ... Random number generation unit, 36 ...
Clock, 37, 48 ... interface, 3
8, 49 ... connector, 50 ... wire,
51 ... charger,

Claims (3)

[Claims] 1. A wireless communication system in which a secret code is unified between a base station and a wireless device, and modulation and demodulation is performed by the secret code to perform wireless communication. And a designated signal of a confidential code is supplied from the base station to the wireless device via the wired connection. 2. The wireless communication system according to claim 1, wherein a wire connected to the base station is connected to the wireless device via a charger of the wireless device. 3. A random number generating means for generating a random number as a designated signal of the secret code at a predetermined time, storing a plurality of secret codes and outputting a secret code corresponding to the generated random number. And a modulating / demodulating means for performing modulation / demodulation according to the confidential code, wherein the wireless device stores a plurality of confidential codes and corresponds to a random number transmitted from the base station via a wire. 2. The wireless communication system according to claim 1, further comprising a secret code storage means for outputting a secret code, and a modulation / demodulation means for performing modulation / demodulation according to the secret code.