JP3145222B2 - Wireless communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication apparatus having a function of preventing modification of a radio.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a configuration of a radio communication device 2 which is generally used. In FIG. 3, a wireless device 50 is a device having a general configuration as a transceiver for voice communication, for example, and transmits and receives a radio signal spatially modulated with a voice signal via an antenna 51.

The antenna 51 converts an electric modulation output signal transmitted from the wireless device 50 into a radio wave and transmits the radio wave, and conversely, converts a radio wave spatially transmitted from a communication partner into an electric signal. It is converted and input to the wireless device 50. The coaxial cable 30 transmits a signal between the wireless device 50 and the antenna 51.

[0004] The radio device 50 converts a voice input from a microphone (not shown) connected to the radio device 50 into a modulated signal,
The carrier signal generated in the wireless device 50 is modulated to be a modulated output signal, and the modulated output signal is amplified and transmitted as a radio signal via the coaxial cable 30 and the antenna 51.

On the other hand, at the time of reception, the reception signal captured by the antenna 51 and converted into an electric signal is amplified, detected, and output as an audio signal. It should be noted that there is a wireless communication device in which the wireless device 50 and the antenna 51 are integrally formed and do not have the coaxial cable 30.

[0006]

For example, a user cuts the coaxial cable 30 at a portion shown in FIG. 3A and inserts a transmission power amplifier into this portion to increase the output. Easy remodeling may be performed, and such remodeling may result in usage that deviates from laws and regulations, or failure of the wireless device 50 or the like. Therefore, there is a demand for a measure for the wireless communication device to make the above-described modification impossible.

A wireless communication device of the present invention has been made in view of the above-described problems, and an object thereof is to provide a wireless communication device capable of preventing easy modification of a wireless communication device of a general user. Aim.

[0008]

In order to achieve the above-mentioned object, a radio communication apparatus according to the present invention comprises a pair of conductors, connects between a radio apparatus and an antenna, and transmits a signal between them. The antenna is connected to form a current loop while performing transmission, and has a transmission line provided integrally with the wireless device, an antenna, a wireless device, and an impedance that does not affect the impedance characteristics of the transmission line, Or a loop current impedance element connected to the transmission line, a signal source for supplying a DC electric signal or an AC electric signal to the current loop, and a detection resistor inserted in the current loop. Detecting means for detecting a voltage generated in the current loop, or a current flowing in the current loop, and asserting a detection signal when these voltages or currents are out of a certain range; And a control means for serial detection signal prohibits the operation of the predetermined portion of the wireless device when it is asserted.

[0009]

The loop resistor connected between the antenna elements forms a path for a search current (loop current) output from the radio. This current generates a voltage at the detection resistor, and the detection circuit detects this voltage to determine whether any modifications have been made on the coaxial cable. When the detection circuit detects that any modification has been made on the coaxial cable, the transmission output control unit controls the radio unit to prohibit the transmission operation and the like.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the wireless communication apparatus according to the present invention will be described below. FIG. 1 is a diagram showing a configuration of a wireless communication device 1 to which the wireless communication device of the present invention is applied. In FIG. 1, a wireless unit 11 has a transmission function and a reception function for general wireless communication, and performs wireless communication of voice, data, and the like. The radio unit 11 further has a function of deactivating the transmission function under the control of the transmission output control unit 12.

The transmission output control unit 12 controls the detection circuit 14
That some modifications were made on the coaxial cable
If it is detected, the transmission function of the radio unit 11 is deactivated (transmission
Prohibition). The voltage source 13 is, for example, a three-terminal regulator.
The detection resistor (R ₁For 17)
And outputs a predetermined voltage value, for example, 12V.

The detection circuit 14 includes a voltage comparator, a reference voltage generation circuit, and the like. The detection circuit 14 detects a voltage value applied to the detection resistor 17 at a point indicated by (b) in FIG. Is outside the predetermined range, it detects that some modification has been made on the coaxial cable, and inputs (asserts) a modification detection signal to the transmission output control unit 12 with a logical value of 1 (asserted).

FIG. 2 is a diagram showing a configuration of the detection circuit 14. As shown in FIG. 2, resistors 141 to 143 divides the power supply voltage (V _CC) min produces two reference voltages for the voltage value detection (V _H, V _L). Here, the reference voltage _VL is
Coaxial cable 30 and loop resistor 2 for antenna 20
This is a reference voltage, for example, 4 V, for detecting that the value of the current flowing through 1 has decreased, that is, that the resistance value of the current loop formed by the coaxial cable 30 and the like has increased.

Here, the reference voltage V _H is the same as that of the coaxial cable 3.
At a reference voltage, for example, 8 V, for detecting that the current value flowing through the loop resistor 21 of the antenna 0 and the antenna 20 has increased, that is, the resistance value of the current loop formed by the coaxial cable 30 or the like has decreased. is there. The values of these reference voltages V _H and V _L are not limited to those shown here, but should be changed according to the configuration of the wireless communication device 1. In particular, when the length of the coaxial cable 30 is constant as a product specification, it is preferable to reduce the difference between the reference voltages _VH and _VL .

The voltage comparator 144 compares the voltage input from the detection resistor 17 with the reference voltage V _H, and outputs a logical value 0 when the input voltage is higher than the reference voltage V _H. The voltage comparator 145 compares the voltage input from the detection resistor 17 with the reference voltage _VL, and outputs a logical value 0 when the input voltage is lower than the reference voltage _VL . NAND circuit 14
6 is N for the output signals of the voltage comparators 144 and 145.
Perform an AND operation.

With the above configuration, the detection circuit 14 outputs the logical value 0 when the voltage input from the detection resistor 17 is within the range of the reference voltage _VH to the reference voltage _VL , and outputs the logical value 0 outside this range. In some cases, a logical value 1 is output.

The capacitor (C) 15 has sufficient characteristics and capacity to pass a high-frequency signal input / output to / from the radio unit 11, passes this high-frequency signal, and blocks a loop current to the radio unit 11. I do.

The high frequency choke (L) 16 is
It has sufficient characteristics and inductance to block a high-frequency signal input to and output from the antenna, blocks this high-frequency signal, and passes a loop current to the antenna 20 and the coaxial cable 30. The detection resistor 17 is a loop current detection resistor having a resistance value of, for example, 5 KΩ. Grounding resistor 18
Has a resistance value of, for example, 100 KΩ, and grounds the voltage detection terminal of the detection resistor 17 shown in FIG. The above components constitute the wireless device 10 of the present invention.

The antenna 20 is composed of a loop resistor 21 and antenna elements 22 and 23. The antenna 20 converts an electric modulation output signal transmitted from the radio device 10 into a radio wave and transmits the radio wave. The radio wave transmitted spatially from is converted into an electric signal and input to the wireless device 10.

The loop resistor 21 is connected to the antenna 20
Has a resistance value that does not disturb the impedance characteristic of the coaxial cable 30, for example, has a resistance value of 5 KΩ, and connects the inner conductor and the outer conductor of the coaxial cable 30 to form a path for the current supplied from the voltage source 13. Since the detection resistor 17 and the loop resistor 21 are both 5 KΩ, the voltage input to the detection circuit 14 is approximately (（) of the output voltage of the voltage source 13, that is, approximately 6V.

The coaxial cable 30 transmits a high-frequency signal between the radio device 10 and the antenna 20. Here, the coaxial cable 30 is not connected by a connector, but is directly connected to the radio device 10 and the antenna 20. In order to separate the radio device 10 from the antenna 20, it is necessary to cut the coaxial cable 30. Each part of the wireless communication device 1 is connected as shown in FIG. In some cases, the coaxial cable 30 is housed inside the wireless device 10 and the wireless device 10 and the antenna 20 are formed integrally.

The operation of the wireless communication device 1 according to the present invention will be described below. The radio device 10 converts a voice input from a microphone (not shown) connected to the radio device 10 into a modulation signal, modulates a carrier signal generated in the radio device 10 into a modulation output signal, and outputs the modulation output signal. Amplify the signal and coaxial cable 30
Then, the signal is transmitted as a radio signal via the antenna 20. On the other hand, at the time of reception, the reception signal captured by the antenna 20 and converted into an electric signal is amplified, detected, and output as an audio signal.

Here, a case where the coaxial cable 30 is cut at a position shown in FIG. 1A and a transmission booster amplifier is connected will be described. For example, when the input of the transmission booster amplifier is coupled to the coaxial cable 30 by a transformer, the inner conductor and the outer conductor of the coaxial cable 30 are short-circuited in terms of direct current.

In such a case, the voltage generated in the detection resistor 17 becomes as high as about 12 V, and becomes higher than the reference voltage _VL . In this case, the output of the voltage comparator 144 of the detection circuit 14 has a logical value of 0, and the output of the detection circuit 14 has a logical value of 1
Becomes

When the input of the transmission booster amplifier is coupled to the coaxial cable 30 by a capacitor, for example, the inner conductor and the outer conductor of the coaxial cable 30 are insulated from a direct current. In such a case, the voltage generated in the detection resistor 17 becomes 0 V, and the reference voltage V
_H or more. In this case, the voltage comparator 1 of the detection circuit 14
The output of 45 becomes a logical value 0, and the output of the detection circuit 14 becomes a logical value 1.

As described above, the detection circuit 14 detects the voltage input from the detection resistor 17 when something is inserted into the coaxial cable 30 and the electric resistance of the path through which the loop current flows falls outside a certain range. It is possible to detect that any alteration has been made on the coaxial cable due to the change in. When the alteration is detected, the detection circuit 14 asserts an alteration detection signal and inputs the signal to the transmission output control unit 12.

When the alteration detection signal is asserted, the transmission output control unit 12 prohibits the operation of the transmission unit of the radio unit 11. As a method of prohibiting the operation of the transmission unit of the radio unit 11, the power of the transmission unit is turned off by a semiconductor element or a mechanical relay. Further, the generation of the carrier signal is stopped. Also, input of voice and data is prohibited. Also, various methods are conceivable, such as changing the bias of the transistor of the power amplifier circuit to a cutoff state. In addition, not only the transmission part of the radio unit 11 but also the operation of the reception part,
Alternatively, the configuration may be such that the operation of only the receiving part is prohibited.

Although a DC power supply is used as a loop current power supply in this embodiment, an AC power supply, for example, an oscillator in an audio frequency band may be used as a loop current power supply. In this case, by providing the detection circuit 14 with a smoothing circuit for rectifying and smoothing the alternating current, it is possible to obtain the same effect with almost the same circuit as the wireless communication device 1.

The location of the loop resistor 21 is not limited to the portion shown in FIG. 1, but may be any location near the end of the coaxial cable 30. Further, although the constant voltage power supply is used as the voltage source 13, a constant current power supply may be used instead of the constant voltage power supply. In this case the wireless communication apparatus 1, it is possible to obtain a reference voltage V _L, V _H similar effect only make changes without changing the other respective part of the. In this embodiment, the voltage generated in the detection resistor 17 is detected by the detection circuit 1.
Although the detection is performed in step S4, the current flowing through the detection resistor 17 may be detected.

As described above, according to the wireless communication apparatus of the present invention, the user can easily perform wireless communication simply by adding relatively simple circuits such as the above-described parts to the wireless device 10 or the like. Modification of the device 1 can be prevented. In addition to the above, the wireless communication device of the present invention can adopt various configurations, for example, as shown as modified examples in the embodiments.
The embodiments described above are merely examples.

[0031]

As described above, according to the present invention, it is possible to provide a radio communication device that can prevent easy modification of a radio communication device of a general user.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a wireless communication device of the present invention.

FIG. 2 is a diagram illustrating a configuration of a detection circuit.

FIG. 3 is a diagram showing a configuration of a wireless communication device generally used conventionally.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Radio | wireless communication apparatus 10 ... Radio | wireless apparatus 11 ... Radio | wireless part 12 ... Transmission output control part 13 ... Voltage source 14 ... Detection circuit 15 ... Capacitor 16 ... High frequency choke DESCRIPTION OF SYMBOLS 17 ... Detection resistance 18 ... Grounding resistance 20 ... Antenna 21 ... Loop resistance 22,23 ... Antenna element 30 ... Coaxial cable

Claims (1)

(57) [Claims] 1. A radio communication system comprising a pair of conductors, which connects between a radio device and an antenna, transmits signals between them and forms a current loop, and is provided integrally with the radio device. A transmission line, an antenna, a wireless device, and an impedance that does not affect the impedance characteristics of the transmission line,
Alternatively, a loop current impedance element connected to the transmission line, a signal source for supplying a DC electric signal or an AC electric signal to the current loop, and a detection resistor inserted in the current loop. Detecting means for detecting a generated voltage or a current flowing through the current loop, and asserting a detection signal when these voltages or currents are out of a predetermined range; and detecting the radio signal when the detection signal is asserted. A wireless communication device having control means for inhibiting operation of a predetermined portion of the device.