JP2002176374A - Radio communication system, antenna device and communication terminal equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system which can easily be loaded on a vehicle and realizes bi-directional communication. SOLUTION: Radio communication equipment is divided into communication terminal equipment 20 and an antenna device 10 and they are connected by one cable 30. A transmission/reception signal processing circuit 21 arranged in communication terminal equipment 20 processes transmission/reception signals and generates a transmission/reception switch signal giving the instruction of the switching of transmission/reception. A voltage control circuit 23 outputs the first voltage signal or a second voltage signal of power different in a voltage based on the transmission/reception switch signal. A control signal generation circuit 17 disposed in the antenna device 10 generates a control signal based on the voltage of the first voltage signal or the second voltage signal. A first switch circuit 12 and a second switch circuit 13 selectively switch/connect a reception circuit 15 and a transmission circuit 16 to an antenna element 11 based on the two control signals.

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, an antenna device, and a communication terminal device mounted on a vehicle such as an automobile.

[0002]

2. Description of the Related Art In recent years, with the development of automobile traffic, a plan for performing two-way communication between a road manager and a traveling vehicle has been promoted. For example, a non-stop automatic toll collection system (ETC) that automatically collects tolls while traveling on a toll road has been put to practical use on a trial basis.

In order to cope with these advanced road traffic systems, it is necessary that each vehicle running on the road is equipped with a wireless communication device. In addition, in order to ensure favorable radio wave conditions in the traveling direction of the vehicle, it is desirable to install a wireless communication device on the dashboard,
There is a possibility that the driving will be hindered. Therefore, it is preferable to separate the communication terminal device, which is the main body portion of the wireless communication device, from the antenna portion and connect them with a coaxial cable to expose the antenna portion on a dashboard or to install the antenna portion on a rearview mirror.

In the above-mentioned ETC system, since the frequency (RF) of radio waves used for wireless communication is extremely high in the 5 GHz band, when a communication terminal device and an antenna portion are coupled with a coaxial cable, the RF in the coaxial cable is reduced. The signal loss increases.

For example, when a communication terminal device is housed in a dashboard and an antenna portion is installed on the dashboard, the coaxial cable needs to be 0.3 to 0.5 m long. Is about 1 dB, and about 2 m when the antenna is installed in the rearview mirror.
Is required, and the loss at this time is about 5 dB. Therefore, not only the installation conditions of the wireless communication device are limited, but also the transmission / reception characteristics such as a decrease in reception sensitivity and a decrease in transmission output may be seriously affected.

Therefore, it is conceivable to install an antenna unit and a transmission / reception amplifier together and connect them to a communication terminal device via a cable. In this case, it is necessary to alternately switch the transmission amplifier and the reception amplifier at the time of transmission and at the time of reception, and power for energizing the transmission amplifier and the reception amplifier is required. Therefore, a plurality of cables such as a cable for transmitting an RF signal, a cable for supplying electric power, and a cable for a control signal for switching between a transmission amplifier and a reception amplifier are usually required. Work became complicated.

For this reason, it is desired that the communication terminal device and the antenna unit be connected by a single cable. For example, FIG.
In the V / H polarization switching device of the CS receiving-only station described in JP-A-5-344014, a low-noise amplifier 1 for V-polarization and a low-noise amplifier for H-polarization are provided on the antenna side. An amplifier 2 is provided, and a polarization switching unit 3 for switching between the amplifiers 1 and 2 is provided. The polarization switching unit 3 is connected to the CS receiver 4 by a single cable 5 to receive a reception signal from the antenna and to switch the DC power from the power supply voltage generator 6 via the cable 5 to the polarization. To section 3.

The polarization switching unit 3 includes a V / H switch 7 for switching and connecting the amplifiers 1 and 2, and a control voltage converter 8 for generating a control voltage for switching the V / H switch 7. When the power supply voltage generator 6 generates a negative voltage of, for example, 15 V,
By switching the V / H switch 7 with the control voltage of V, CS
The receiver 4 is connected to the amplifier 1 for V polarization, and the V
A negative 15 V power for operating the amplifier 1 is supplied through the / H switch 7.

When the power supply voltage generator 6 generates a negative voltage of 24 V, the V / H switch 7 is switched to the H polarization amplifier 2 by the control voltage of 0 V output from the control voltage converter 8. Side, and sends a received signal of H polarization to the CS receiver 4, and supplies negative 24 V power to the amplifier 2 through the V / H switch 7.

[0010]

However, the conventional example is a circuit dedicated to receiving CS radio waves, and switches between the low noise amplifiers 1 and 2 with the switching of the V / H polarization. 2 does not include a power amplifier for transmission, and is not mounted on a vehicle to suitably realize two-way communication.

In the conventional example, a negative 15 V
And the amplifier 2 is supplied with negative 24V power, so that two low-noise amplifiers dedicated to reception use power having two voltage values,
There is a problem that the configuration of the amplifier is limited such that an amplifier having the same configuration cannot be used.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a transmission / reception circuit on an antenna side to secure sufficient reception sensitivity and transmission power irrespective of a loss in a cable. To provide a wireless communication system.

Another object of the present invention is to provide an antenna device in which a transmission / reception circuit is provided on the antenna side to improve noise characteristics.

Still another object of the present invention is to control the operation of an antenna device and to provide sufficient power to the antenna device in a wireless communication system in which a communication terminal device and an antenna device are connected by a single cable. An object of the present invention is to provide a communication terminal device for supplying.

[0015]

In order to achieve the above object, the present invention has the following structure to solve the problem. That is, a wireless communication system according to a first aspect of the invention is a wireless communication system in which a communication terminal device and an antenna device are connected by a single cable, wherein the communication terminal device includes: a power supply that supplies DC power; And a transmission / reception signal processing circuit that outputs a transmission signal and generates a transmission / reception switching signal, and a first voltage signal or a second voltage having different voltage values based on the transmission / reception switching signal based on the power supplied from the power supply. A voltage control circuit for converting the signal into a signal and outputting the signal; and a superimposing circuit for transmitting the reception signal to the transmission / reception signal processing circuit and transmitting the transmission signal and the voltage signal of the first voltage signal or the second voltage signal via a cable. The antenna device transmits and receives a radio signal to a superimposing circuit via a cable and transmits and receives a transmission signal input from the superimposing circuit via a cable. A distribution circuit that separates signals, a control signal generation circuit that generates a control signal based on the voltage value of the voltage signal, a reception circuit that operates when receiving radio waves, a transmission circuit that operates when transmitting radio waves, and a reception circuit Alternatively, a first switch circuit and a second switch circuit that switch and connect a transmission circuit to an antenna element and a distribution circuit by a control signal, and a constant voltage circuit that converts a voltage signal into power of a predetermined voltage value and drives the antenna device. With the configuration provided, this is a means for solving the problem.

In the above invention, the power source is a charger for a vehicle or the like that supplies DC power having a constant voltage value. At the time of reception, the transmission / reception signal processing circuit generates a reception switching signal,
The voltage control circuit to which the switching signal is input sends a first voltage signal having sufficient power to drive the switching device to the superposition circuit. The distribution circuit sends the first voltage signal supplied via the cable to the control signal generation circuit and the constant voltage circuit.

The control signal generation circuit compares the first voltage signal with a threshold value, and switches the first switch circuit and the second switch circuit to the receiving side when, for example, the first voltage signal is lower than the threshold value. Send a control signal. With this control signal, the first switch circuit and the second switch circuit switch and connect the receiving circuit to the antenna element and the distribution circuit. The receiving circuit can be constituted by a low-noise amplifier circuit, and can include a filter circuit for removing noise.

The constant voltage circuit converts the power of the first voltage signal into a DC voltage having a stable set voltage value and supplies the DC voltage to, for example, a control signal generating circuit and a receiving circuit to energize the entire switch device. The circuit of the wireless communication system is set to be receivable.

In this circuit state, when the antenna element receives a radio wave, the received signal passes through the receiving circuit and the noise characteristics are improved, and the received signal with good noise characteristics is superimposed via the distribution circuit and the cable. It is supplied from the circuit to the transmission / reception signal processing circuit. The transmission / reception signal processing circuit can reliably process the meaning of the received signal.

At the time of transmission, the transmission / reception signal processing circuit
The voltage control circuit that generates the transmission switching signal and receives the switching signal transmits a second voltage signal having sufficient power to operate the switching device to the distribution circuit via the superimposing circuit. The distribution circuit sends the second voltage signal to the control signal generation circuit and the constant voltage circuit as described above. The control signal generation circuit compares the second voltage signal with a threshold value, and
When the voltage signal is higher than the threshold, a control signal for switching the first switch circuit and the second switch circuit to the transmission side is generated.

According to this control signal, the first switch circuit and the second switch circuit perform a switching operation to switch and connect the transmission circuit to the antenna element and the distribution circuit. The transmission circuit can be configured as a power amplification circuit. The constant voltage circuit converts the power of the second voltage signal into a stable DC voltage having the same set voltage value as described above, and energizes the entire switch device.

In this circuit setting, when the transmission / reception signal processing circuit sends out a transmission signal, the transmission signal is superimposed on the second voltage signal in the superimposition circuit, and the superimposed signals (the transmission signal and the second voltage signal) are transmitted. It is sent to the distribution circuit via the cable. The transmission signal is separated from the second voltage signal in the distribution circuit, passes through the transmission circuit, and is radiated from the antenna element as a radio wave having a sufficient electric field strength. Signal transmission and reception are repeated by the above-described reception operation and transmission operation.

In a wireless communication system according to a second aspect of the present invention, in the above-mentioned invention, the control signal generating circuit has a threshold value for the input voltage, and the voltage value of the input voltage signal is higher than the threshold value. The first switch circuit and the second switch circuit generate different control signals based on whether they are high or low.
When one control signal is input, the receiving circuit is switched and connected to the antenna element and the distribution circuit, and when the other control signal is input, the transmission circuit is switched and connected to the antenna element and the distribution circuit. It is characterized in that a first voltage signal having a voltage value higher than the threshold value of the generation circuit and a second voltage signal having a voltage value lower than the threshold value are alternatively supplied.

In the above-described configuration, the threshold value of the control signal generation circuit serves as a reference for judging the magnitude of the first voltage signal and the second voltage signal supplied from the voltage control circuit. That is, the control signal generation circuit generates a control signal for switching the first switch circuit and the second switch circuit to, for example, reception when the first voltage signal larger than the threshold value is input, When a smaller second voltage signal is input, for example, a control signal for switching to transmission is generated. By this switching operation, the reception circuit and the transmission circuit are alternatively connected to the antenna element and the distribution circuit, and the antenna device is set to receive or transmit.

In the wireless communication system according to the third invention, the second communication system
In the invention, the control signal generation circuit includes a first threshold value and a second threshold value having a voltage value lower than the first threshold value, and a second voltage signal lower than the second threshold value. , A first control signal is generated, and a first control signal higher than a first threshold value is generated.
A second control signal is generated when a voltage signal is input.

In this configuration, a predetermined voltage difference is provided between the first threshold value and the second threshold value held by the control signal generation circuit. Therefore, even when the voltage difference between the first voltage signal and the second voltage signal generated by the voltage control circuit is small, the first control signal and the second control signal can be kept constant by comparing the two threshold values. A clear control signal having a voltage difference of

In a wireless communication system according to a fourth aspect of the present invention, in any one of the above-mentioned inventions, the control signal of the control signal generating circuit is the first control signal or the second control signal having a lower voltage value than the first control signal. One control signal controls the energization of a reception circuit or a transmission circuit switched and connected by the first switch circuit and the second switch circuit, and the other control signal controls the first switch circuit and the second switch circuit. The transmission circuit or the reception circuit switched off by the switch circuit is deactivated control.

By employing this configuration, using the first control signal and the second control signal, for example, by using the second control signal,
When connecting the receiving circuit to the antenna element and the distribution circuit and energizing the receiving circuit, control for disconnecting the transmission circuit from the antenna element and the distribution circuit and deactivating the transmission circuit is performed by the same second control signal, Conversely, for example,
When the transmission circuit is connected and energized by the first control signal, control for disconnecting and deactivating the reception circuit is performed by the same first control signal.

In a wireless communication system according to a fifth aspect of the present invention, in any one of the above-mentioned inventions, the first switch circuit and the second switch circuit
The switch circuit has a first control terminal for switching connection of the reception circuit to the antenna element and the distribution circuit, and a second control terminal for switching connection of the transmission circuit to the antenna element and the distribution circuit. A signal and a second control signal are generated alternatively, one of the control signals is directly input to the first control terminal, and the other is input to the second control terminal via an inverter circuit. .

With this configuration, the switching operation in the first switch circuit and the second switch circuit is performed by the first control terminal.
For example, when the second control signal is input and the control signal corresponding to the first control signal inverted by the inverter circuit is input to the second control terminal, the receiving circuit is switched and connected to the antenna element and the distribution circuit. Conversely, when, for example, a first control signal is input to the first control terminal and a control signal corresponding to the second control signal inverted by the inverter circuit is input to the second control terminal, the transmitting circuit is connected to the antenna. It is switched and connected to the element and the distribution circuit.

According to a sixth aspect of the present invention, in the wireless communication system according to the fifth aspect, the receiving circuit and the transmitting circuit each have a control terminal, and each of the first control signal and the second control signal has one of the control terminals. The control signal is input to the control terminal of the receiving circuit to control the operation of the receiving circuit, and the control signal is input to the control terminal of the transmitting circuit via the inverter circuit to control the operation of the transmitting circuit. .

With this configuration, the energizing and deactivating operations of the receiving circuit and the transmitting circuit are controlled by two contradictory control signals. For example, when the second control signal is input to the control terminal of the receiving circuit, the receiving circuit performs an ON operation, and when a control signal corresponding to the first control signal inverted by the inverter circuit is input to the control terminal of the transmitting circuit, the transmitting circuit Circuit is OFF
This is the circuit setting for operation. Further, when the first control signal is input to the control terminal of the receiving circuit and a control signal corresponding to the second control signal inverted by the inverter circuit is input to the control terminal of the transmitting circuit, the receiving circuit performs an OFF operation and transmits. The circuit is set to the ON operation.

[0033] In a wireless communication system according to a seventh aspect of the present invention, in any one of the above-mentioned aspects, at least one of the receiving circuit and the transmitting circuit includes an amplifier for amplifying a signal. Is supplied.

According to this configuration, the receiving circuit includes the low-noise amplifier, and the transmitting circuit includes the power amplifier. As a result, in the antenna device, gain characteristics and noise characteristics are improved during reception, and sufficient transmission power is obtained during transmission.

If the reception sensitivity of the communication terminal device is good even when the attenuation of the received signal in the cable is taken into consideration, a circuit for relocating the low noise amplifier in the antenna device to the communication terminal device. Configuration is possible. Similarly, a power amplifier can be installed in a communication terminal device when required transmission power is obtained irrespective of attenuation of a transmission signal in a cable.

Further, the above-described constant voltage circuit may receive the first voltage signal or the second voltage signal having different powers of the power value.
The stabilized power of the voltage value is supplied to the receiving circuit and the transmitting circuit. In this case, in consideration of the fact that the power consumption of the transmitting circuit is larger than that of the receiving circuit, the constant voltage circuit is a constant voltage circuit dedicated to supplying power to the receiving circuit and a constant voltage circuit dedicated to supplying power to the transmitting circuit. And a plurality of such devices can be provided.

An antenna device according to an eighth aspect of the present invention is an antenna device for transmitting and receiving a radio wave, and a distribution device for transmitting a reception signal to a communication terminal device and separating a voltage signal including a transmission signal and a control signal input from the communication terminal device. A circuit, a control signal generation circuit that generates a reception or transmission control signal based on the voltage value of the voltage signal, a reception circuit that operates when receiving radio waves, a transmission circuit that operates when transmitting radio waves, and an antenna element. A first switch circuit and a second switch circuit for switching connection of a reception circuit by a reception control signal and switching connection of a transmission circuit by a transmission control signal between the distribution circuits; And a constant voltage circuit for driving a power consuming circuit including a receiving circuit and a transmitting circuit after conversion.

In the antenna device according to the present invention, the control signal generating circuit, based on the known voltage signal supplied from the communication terminal device, controls the first switch circuit and the second switch circuit to receive or transmit. Occurs. By this operation, the first switch circuit and the second switch circuit
In the case of a reception control signal, a reception circuit is connected between the antenna element and the distribution circuit to set a circuit in the antenna device so that radio waves can be received. And a circuit is set in the antenna device so that radio waves can be transmitted from the antenna element.

Further, the constant voltage circuit supplies stabilized DC power to the power consuming circuit in the antenna device even if the voltage value of the input voltage signal fluctuates according to a known meaning. To operate stably. here,
The power consumption circuit refers to a circuit that consumes power in the antenna device, such as a reception circuit, a transmission circuit, and a control signal generation circuit.

In an antenna apparatus according to a ninth aspect, in the eighth aspect, the first switch circuit and the second switch circuit include a first switch terminal and a second switch terminal, and are provided between the first switch terminals. A reception circuit is connected, a transmission circuit is connected between the second switching terminals, and a first control terminal and a second control terminal for inputting a reception or transmission control signal are provided. The first switch circuit connects the antenna element. And the second switch circuit has an output terminal for connecting the distribution circuit.

In the present invention, the first switch circuit and the second switch circuit
The switch circuit forms a transmission / reception switching circuit. By employing this switching circuit, for example, when a reception control signal is input to the first control terminals of the first switch circuit and the second switch circuit, and a transmission control signal is input to the second control terminal, the reception circuit is switched to the antenna. Switched between the element and the distribution circuit,
Radio waves can be received. Conversely, for example, the first
When a control signal for transmission is input to the control terminal and a control signal for reception is input to the second control terminal, the transmission circuit is switched between the antenna element and the distribution circuit to enable transmission of radio waves.

In the antenna apparatus according to a tenth aspect, in the ninth aspect, the control signal for receiving or transmitting is controlled between the second control terminal and the control signal generating circuit. The inverter is connected to a signal converting circuit.

By employing this configuration, one of the reception or transmission control signals output from the control signal generation circuit is used to generate the other control signal. By using the reception control signal and the transmission control signal, the reception circuit and the transmission circuit are switched between the antenna element and the distribution circuit.

According to an eleventh aspect of the present invention, in any one of the eighth to tenth aspects, the receiving circuit comprises a low-noise amplifier having a control terminal for inputting a control signal. Is characterized by comprising a power amplifier having a control terminal for inputting a control signal.

In this configuration, for example, the low-noise amplifier is operated when a control signal for reception is input to the control terminal of the low-noise amplifier constituting the reception circuit, and the operation is stopped when the control signal for transmission is input. Similarly, control is performed such that the operation of the power amplifier is stopped when a control signal for reception is input to a control terminal of the power amplifier constituting the transmission circuit, and is operated when a control signal for transmission is input.

According to a twelfth aspect of the present invention, a communication terminal device processes a reception signal input from an antenna device, outputs a transmission signal to be transmitted to the antenna device, and outputs a transmission signal to the antenna device. A transmission / reception signal processing circuit for generating a transmission / reception switching signal for controlling a transmission / reception switching operation; and converting the power supplied from the DC power supply into a first voltage signal or a second voltage signal having different voltage values based on the transmission / reception switching signal. A voltage control circuit for converting and outputting the signal; and a superimposing circuit for transmitting the reception signal to the transmission / reception signal processing circuit and transmitting the transmission signal and the voltage signal of the first voltage signal or the second voltage signal via a cable. It is configured as a feature.

In the present invention, the transmission / reception signal processing circuit functions as a control tower for controlling the antenna device when performing bidirectional communication, and generates a reception switching signal during reception and generates a transmission switching signal during transmission. The voltage control circuit that has received the transmission / reception switching signal generates a known first voltage signal or second voltage signal in the antenna device. These voltage signals include DC power sufficient to be consumed in the antenna device, and also include a command signal for switching between a receiving circuit and a transmitting circuit in the antenna device.

The transmission / reception signal processing circuit has a circuit configuration conforming to the communication system, and can include an amplifier operating at the time of reception and an amplifier operating at the time of transmission, if necessary. In addition, data necessary for two-way communication is stored in a storage device.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a radio communication system according to the present invention will be described with reference to the drawings. In FIG. 1, the wireless communication system includes an antenna device 10 and a communication terminal device 20, and the antenna device 10 and the communication terminal device 20 are connected by one coaxial cable 30. The antenna device 10 receives the radio frequency, for example,
The 5.8 GHz signal (RF signal) is amplified and transmitted to the communication terminal device 20 via the coaxial cable 30. At this time, the antenna device 10 is supplied with DC power having a voltage value of, for example, 3.5 V from the communication terminal device 20 via the coaxial cable 30.

The RF signal transmitted from the communication terminal device 20 via the coaxial cable 30 is
The power is amplified and transmitted. Also at this time, the antenna device 10 receives the supply of DC power from the communication terminal device 20 via the coaxial cable 30, but has a different DC power from that at the time of reception, for example, a DC voltage of 4.5 V. The difference between the voltage values of 3.5 V and 4.5 V is a command signal for switching the antenna device 10 to reception or transmission.

The above-described antenna device 10 will be described in detail.
The antenna device 10 includes an antenna element 11, which is connected to an input terminal 1 of a first switch 12.
2a. The first changeover switch 12 includes two changeover terminals 12b and 12c and a control terminal 12d,
The input terminal 12a is selectively connected to the switching terminal 12b or the switching terminal 12c by a control signal input to the control terminal 12d.
Is switched and connected.

The antenna device 10 is provided with a second changeover switch 13 cooperating with the first changeover switch 12, and its output terminal 13 a is connected to the input terminal of the distribution circuit 14. The second changeover switch 13 is provided with two changeover terminals 13b, 13c and a control terminal 13d. As described above, the output terminal 13a is switched to the changeover terminal 13b or the changeover terminal 13 by the control signal input to the control terminal 13d. 13c is alternatively connected.

A low-noise amplifier 15 constituting a receiving circuit is connected between the switching terminal 12b of the first switch 12 and the switching terminal 13b of the second switch 13.
A power amplifier 16 constituting a transmission circuit is connected between the switching terminal 12c of the first switch 12 and the switching terminal 13c of the second switch 13. Low noise amplifier 1
5 is provided with a control terminal 15a for inputting a control signal for controlling the operation of the amplifier 15.
Similarly, a control terminal 16a for inputting a control signal for controlling the operation of the amplifier 16 is provided on the low noise amplifier 15 as well.
When N), the power amplifier 16 is controlled so as to stop operating (OFF).

The above-described low-noise amplifier 15 includes a control terminal 15
Operates (ON) when a 3V control signal is input to a
When the control signal of V is input, the operation is controlled to stop (OFF). The power amplifier 16 stops operation (OFF) when a control signal of 3V is input to the control terminal 16a,
Is activated (ON) when the control signal is input.

For example, as shown in FIG. 2, the distribution circuit 14 includes a DC cut capacitor 14a connected between the connector 31 of the coaxial cable 30 and the output terminal 13a of the second changeover switch 13, and 31 and connected between the control signal generating circuit 17 and the DC constant voltage circuit 18,
And an inductor 14b for blocking the RF signal. With this configuration, the distribution circuit 14 transmits the received signal input from the output terminal 13 a of the second changeover switch 13 to the communication terminal device 20 via the coaxial cable 30, and also transmits the received signal from the communication terminal device 20 via the coaxial cable 30. The transmitted transmission signal is transmitted to the output terminal 13a of the second changeover switch 13.

The distribution circuit 14 is connected to the communication terminal device 20.
, DC voltage having a voltage value of 3.5 V or 4.5 V is input through the connector 31 of the coaxial cable 30. This DC power is separated by the capacitor 14a and the inductor 14b, and sent to the input terminals of the control signal generation circuit 17 and the DC constant voltage circuit 18.

The control signal generation circuit 17 provides two threshold values Vs1 and Vs2 for the input DC power voltage value.
(Vs1> Vs2). For example, the first threshold value Vs1 is 4.1 V of the DC voltage, and the second threshold value Vs2 is 3.9 V of the DC voltage. When the voltage value DCVin of the input power is smaller than the second threshold value Vs2 having a low voltage value (3.9V> DCVin), the control signal generation circuit 17 outputs a control signal of the voltage value Vc1, for example, 3V of the DC voltage. And transmitted to the control terminals 12d, 13d, 15a, 16a of the first changeover switch 12, the second changeover switch 13, the low noise amplifier 15, and the power amplifier 16, respectively.
As a result, the first changeover switch 12 and the second changeover switch 13 are switched to the reception-side changeover terminals 12b and 13b, so that the low-noise amplifier 15 is turned on (ON) and the power amplifier 16 is turned off (OFF).

When the voltage value DCVin input to the control signal generation circuit 17 is greater than the first threshold value Vs1 having a high voltage value (DCVin> 4.1 V), the control signal generation circuit 17 , Generates a control signal having a DC voltage value of 0.1 V to control the first changeover switch 12 and the second changeover switch 13, and the transmission-side changeover terminals 12 c and 13 c
And the operation of the low noise amplifier 15 is stopped (OF
F) to operate (ON) the power amplifier 16.

The DC constant voltage circuit 18 receives a supply of 3.5 V DC power during the reception operation of the antenna device 10, and receives a 4.5 V DC power during transmission. This DC constant voltage circuit 18 is composed of, for example, a regulator, and has two voltage values of 3.5 V or 4.5.
The V power is converted to a stabilized DC voltage, for example, 3 V power, and becomes power for driving the antenna device 10. For example, 3 V power is supplied to the control signal generation circuit 17 and about 3 V is supplied to the 3 V driven low noise amplifier 15.
0 mW of power is supplied, and about 300 mW of power is supplied to the power amplifier 16.

Next, the communication terminal device 20 will be described in detail. The communication terminal device 20 includes a transmission / reception signal processing circuit 21. This transmission / reception signal processing circuit 21
2 for processing the received signal input from the
And a transmission / reception switching signal for instructing the voltage control circuit 23 to perform a transmission / reception switching operation in the antenna device 10. Further, the transmission / reception signal processing circuit 21 includes, for example, an RF circuit such as a modulation / demodulation circuit, a digital signal processing circuit using a DSP (digital signal processor) or the like, which is suitable for the communication system to be used.
Further, it holds data such as identification information of a vehicle equipped with the communication terminal device 20 and credit information of a driver.

For example, as shown in FIG. 3, the superimposing circuit 22 includes a capacitor 22a connected between the connector 32 of the coaxial cable 30 and the transmission / reception signal processing circuit 21, and a connection between the connector 32 and the voltage control circuit 23. The capacitor 22a prevents the direct current supplied from the voltage control circuit 23 from flowing into the transmission / reception signal processing circuit 21.
2b, a high-frequency reception signal transmitted from the antenna device 10 via the coaxial cable 30 and a transmission signal transmitted from the transmission / reception signal processing circuit 21 are connected to the voltage control circuit 23.
To prevent leakage.

With this configuration, the superimposing circuit 22 sends the received signal input from the antenna device 10 via the coaxial cable 30 to the transmission / reception signal processing circuit 21 and also transmits the transmission signal input from the transmission / reception signal processing circuit 21 to the coaxial cable. 30 to the antenna device 10.

The DC power supply 24 is, for example, a DC power supply for a battery mounted on a vehicle, and supplies DC power to the voltage control circuit 23. The voltage control circuit 23 converts the DC voltage supplied from the DC power supply 24 into electric power having a voltage value of 3.5 V or 4.5 V based on the transmission / reception switching signal transmitted by the transmission / reception signal processing circuit 21.

That is, when receiving a reception switching signal for switching the operation of antenna apparatus 10 to reception from transmission / reception signal processing circuit 21, voltage control circuit 23 sends out DC power having a voltage value of 3.5 V to superposition circuit 22. . This DC power is
The signal is supplied from the superposition circuit 22 to the distribution circuit 14 of the antenna device 10 through the coaxial cable 30. Further, the voltage control circuit 23 transmits the transmission / reception signal processing circuit 21 to the antenna device 10.
When a transmission switching signal for switching the operation to the transmission is input, the voltage control circuit 23 generates a DC power having a voltage value of 4.5 V, and this DC power is supplied to the superposition circuit 22 in the same manner as described above.
The signal is sent to the distribution circuit 14 of the antenna device 10 through the coaxial cable 30.

When the apparatus using the above-described wireless communication system is mounted on a vehicle and used, the driver, for example,
An IC card storing its own credit information and the like is set in the communication terminal device 20. For example, the communication terminal device 20 is initially set to a reception state, and the transmission / reception signal processing circuit 21 sends a reception switching signal to the voltage control circuit 23,
The voltage control circuit 23 applies 3.5 V DC power to the superposition circuit 2.
2 to the antenna device 10.

In the antenna device 10, the constant voltage circuit 18
Converts the 3.5 V DC power supplied through the distribution circuit 14 into the stabilized 3 V DC power and supplies the stabilized DC power to the control signal generation circuit 17, the low noise amplifier 15, and the power amplifier 16 to operate these circuits. Make it possible. The control signal generation circuit 17 compares the input voltage of 3.5 V with a threshold of 3.9 V, and after confirming that the input voltage is lower than the threshold, generates a control signal of 3 V. .

On the other hand, the first change-over switch 12 and the second change-over switch 13 are initially set to receive signals.
The state where the low noise amplifier 15 is connected between the antenna element 11 and the distribution circuit 14 is maintained by the input of the V control signal. In parallel with this, the low noise amplifier 15 to which the control signal of 3 V is input starts operating, and the power amplifier 16
The operation is stopped (OFF) at the control voltage of 3V. This OFF operation can save about 300 mW of power.

When the antenna element 11 receives a radio wave, the received signal is transmitted by the low noise amplifier 15 to the coaxial cable 3.
Amplification is performed with a gain that compensates for the amount of attenuation at 0, and the reception sensitivity is kept good. The amplified high-frequency reception signal is supplied to the capacitor 14a of the distribution circuit 14 and the superposition circuit 22.
, And is sent to the transmission / reception signal processing circuit 21 for signal processing. For example, when the signal is a reception signal when the vehicle approaches a tollgate, a response signal is transmitted from the transmission / reception signal processing circuit 21 as a transmission signal.

When the transmission / reception signal processing circuit 21 outputs a transmission signal, it first sends a transmission switching signal to the voltage control circuit 23. The voltage control circuit 23 that has received the transmission switching signal converts the DC power supplied from the DC power supply 24 to 4.5.
The power is converted into the power of the voltage value of V. The 4.5 V DC power output from the voltage control circuit 23 is supplied to the antenna device 10 via the inductor 22 b of the superposition circuit 22 and the coaxial cable 30.
Sent to

In the antenna device 10, the control signal generation circuit 17 and the constant voltage circuit 18 receive a 4.5 V DC power supply through the distribution circuit 14. Thus, the control signal generation circuit 17 compares the input voltage of 4.5 V with the threshold value of 4.1 V, confirms that the input voltage is higher than the threshold value, Outputs control signal.
The constant voltage circuit 18 outputs stabilized DC power having a voltage value of 3V.

Here, the first changeover switch 12 and the second changeover switch 13 switch to transmission, and a power amplifier 16 is connected between the antenna element 11 and the distribution circuit 14. Also,
The low-noise amplifier 15 that has received the control signal of 0.1 V stops operation (OFF), and conversely, the power amplifier 16 starts operation at the control voltage of 0.1 V. Low noise amplifier 15 is off
As a result, a power saving of about 30 mW can be achieved.

In this circuit state, the transmission / reception signal processing circuit 21 generates a response signal to the above-mentioned toll gate, for example. For example, when the vehicle enters a toll road, data such as vehicle identification information is read out from the memory (ROM) of the transmission / reception signal processing circuit 21. For example, data such as driver's credit information is read from the IC card and transmitted as a transmission signal. The high-frequency transmission signal output from the transmission / reception signal processing circuit 21 passes through the capacitor 22a of the superposition circuit 22, the coaxial cable 30, and the capacitor 14a of the distribution circuit 14, and is compensated for the attenuation of the coaxial cable 30 in the power amplifier 16. The signal is amplified by a gain including the frequency component and transmitted from the antenna element 11 as a transmission signal of a predetermined power.

As described above, the low noise amplifier 15 or the power amplifier 16 is selectively switched and connected based on the transmission / reception switching signal of the transmission / reception signal processing circuit 21 at the time of transmission or reception. Since the switches are separated from the transmission path for the communication terminal device 20 by using the changeover switches 12 and 13, abnormal oscillation of the amplifier due to formation of a closed loop and increase in high-frequency noise can be prevented.

A second embodiment of the radio communication system according to the present invention will be described with reference to FIG. The same components as those of the first embodiment are denoted by the same reference numerals, and the description of the common components will not be repeated. In this embodiment, the antenna device 1
0 is characteristic. That is, the inverter circuit 19 is connected between the control signal generation circuit 17 and the control terminal 16a of the power amplifier 16.
Is connected. The output terminal 19 b of the inverter circuit 19 to which the control terminal 16 a is connected is connected to the second control terminal 12 of the first switch 12 and the second switch 13.
e and 13e, respectively.

This inverter circuit 19 is composed of a constant voltage circuit 1
8, the control signal having a voltage value of 3 V input to the input terminal 19a is converted into a control signal having a voltage value of 0.1V and transmitted from the output terminal 19b. Conversely, when a control signal having a voltage value of 0.1 V is input, a control signal having a voltage value of 3 V is output. The power amplifier 16 is different from the embodiment of FIG.
6a is turned on when the control signal input to 3a is 3V.
OFF operation at 1V.

With this configuration, in the receiving operation of the antenna device 10, when the control signal generation circuit 17 generates a control signal having a voltage value of 3V, the first control of the first switch 12 and the second switch 13 is performed. A control signal of 3V is input to the terminals 12d and 13d, and the second control terminals 12e and 1
A control signal of 0.1 V is input to 3e, and the first changeover switch 12 and the second changeover switch 13 are selectively connected to the changeover terminals 12b and 13b on the receiving side.

At the same time as this operation, the low noise amplifier 1
5 is supplied with a control signal of 3 V to drive the low noise amplifier 15 (ON), and the power amplifier 16
The control signal of 0.1 V is input to the control terminal 16a of the power amplifier 16 to stop (OFF) the operation of the power amplifier 16. As a result, wasteful power consumption at the time of reception by the antenna device 10 can be prevented.

In the transmitting operation of the antenna device 10, when the control signal generating circuit 17 generates a control signal having a voltage value of 0.1 V, the first switch 12 and the second switch First control terminal 12 of switch 13
d and 13d become 0.1 V, and the second control terminals 12e and 1
3e becomes 3V, and switches the first switch 12 and the second switch 13 to the switching terminals 12c and 13c on the transmission side. At the same time, the control terminal 15a of the low noise amplifier 15 becomes 0.1 V and stops its operation (OFF),
The control terminal 16a of the power amplifier 16 becomes 3V and starts (ON) the amplification operation. Also in this case, the power consumption is reduced by stopping the operation of the low noise amplifier 15.

FIGS. 5 and 6 show another embodiment of the transmission / reception circuit in the antenna device 10. FIG. The same components as those of the first embodiment are denoted by the same reference numerals, and the description of the common components will not be repeated. In this embodiment, the transmission / reception circuit includes a low noise amplifier 15 or a power amplifier 1.
6 is not included.

In FIG. 5, the low noise amplifier 15 shown in the embodiment of FIG. 1 is omitted from the antenna device 10, and the switching terminal 12b of the first switch 12 and the switching terminal of the second switch 13 are removed. A transmission line 15b that does not include an amplifier is connected between 13b. The transmission line 15b can be configured to include a filter circuit for removing noise. A power amplifier 16 is connected between the switching terminal 12c of the first switch 12 and the switching terminal 13c of the second switch 13.

If the cable 30 in FIG. 1 for attenuating high-frequency RF signals can be made short, for example, the communication terminal device 20 is installed in contact with a top plate in a dashboard, and the antenna element If only 11 can protrude from the dashboard, the electric field strength of the radio wave in the receiving area during the operation of the vehicle is large, and the receiving sensitivity is sufficient even in consideration of the attenuation of the signal voltage in the cable 30. In particular, when noise characteristics (S / N) can be obtained, the low noise amplifier 15 can be included in the transmission / reception signal processing circuit 21. With this configuration, the circuit configuration of the antenna device 10 can be simplified, and the power consumption of the antenna device 10 can be reduced.

In the embodiment of FIG. 6, the antenna device 10
The power amplifier 16 shown in the embodiment of FIG. 1 is omitted from FIG. 1, and a transmission line 16b is connected between the switching terminal 12c of the first switching switch 12 and the switching terminal 13c of the second switching switch 13 to perform the first switching. A low noise amplifier 15 is connected between the switching terminal 12b of the switch 12 and the switching terminal 13b of the second switching switch 13. Also in this case, the transmission signal is attenuated in the cable 30 in FIG.
By including in the transmission / reception signal processing circuit 21 the power amplifier 16 having a transmission output in consideration of the attenuation of the transmission signal in the cable 30, it is possible to transmit from the antenna element 11 with sufficient power.

As described above, when the cable 30 is very short, an amplifier having the same output power characteristics as when the cable 30 is not used can be used. When the reception sensitivity on the road manager side is good, the antenna can be used. Good transmission and reception can be performed even when the transmission power from the element 11 is low.

[0084]

According to the wireless communication system of the first aspect,
In a wireless communication system in which a communication terminal device and an antenna device are connected by a single cable, even if signal attenuation is large in a cable connecting the antenna device and the communication terminal device, a reception circuit is connected to the antenna device. And the provision of the transmission circuit, it is possible to prevent the reception sensitivity from deteriorating at the time of reception, and to generate a transmission signal having sufficient power at the time of transmission. Therefore, the antenna device can be arbitrarily installed in a place where radio wave conditions are good, regardless of the loss in the cable, and the communication terminal device can be installed in a preferable storage place of the vehicle.

According to the wireless communication system of the second aspect, the first voltage signal and the second voltage signal sent by the voltage control circuit are not used as control signals as they are, but the control signal generation circuit uses the threshold value as a reference. Therefore, the switching operation of the first switch circuit and the second switch circuit can be performed without error.

According to the third aspect of the present invention, the control signal generating circuit generates two control signals having a clear voltage difference by using the two threshold values. The switching operation of the circuit can be reliably performed.

According to the fourth aspect of the present invention, when one of the receiving circuit and the transmitting circuit is connected and operates, the other circuit is cut off and stops its operation. Power consumption can be reduced.

According to the wireless communication system of the fifth aspect, the first switch circuit and the second switch circuit have the first control terminal and the second control terminal, and the control signal input to the first control terminal is supplied to the inverter circuit. Since the control signal is input to the second control terminal via the second control terminal, two opposing control signals are used, so that the reception circuit and the transmission circuit can be reliably switched by the first switch circuit and the second switch circuit.

According to the wireless communication system of claim 6, since the receiving circuit and the transmitting circuit have the control terminal, one of the two control signals input to the control terminal is used to control one of the circuits. It can be controlled to operate and stop the operation of the other circuit by the other control signal. Thereby, the power consumed by the antenna device can be reduced.

According to the wireless communication system of the present invention, at least one of the receiving circuit and the transmitting circuit includes the amplifier, and supplies the stabilized power from the constant voltage circuit. When it is included, even if a weak radio wave is received, by amplifying to compensate for the amount of attenuation in the cable, a received signal with good noise characteristics can be transmitted to the communication terminal device. Also, when the transmission circuit includes an amplifier, the transmission signal can be transmitted from the antenna element with stable power that compensates for the attenuation of the transmission signal in the cable.

According to the antenna device of the eighth aspect, the antenna device is configured to include the receiving circuit and the transmitting circuit and the receiving circuit and the transmitting circuit are selectively switched to operate. Circuit settings can be made so that the gain characteristics and noise characteristics of the receiving circuit are good, and sufficient transmission power can be ensured when transmitting radio waves.

According to the antenna device of the ninth aspect, the switching circuit of the receiving circuit and the transmitting circuit is constituted by using the two switch circuits operated by the control signal.
The receiving circuit and the transmitting circuit can be reliably switched between the antenna element and the distribution circuit.

According to the antenna device of the tenth aspect, another contradictory control signal is generated from one control signal, and the first switch circuit and the second switch circuit are controlled using the two contradictory control signals. Therefore, the switching operation can be reliably performed.

According to the antenna device of the eleventh aspect, since the transmitting / receiving circuit is constituted by the amplifier having the control terminal, the operation of one amplifier operates when the other amplifier operates by the control signal input to the control terminal. By stopping, power consumption by the amplifier can be reduced.

According to the communication terminal device of the twelfth aspect, when mounted on a vehicle, for example, only the circuit functions necessary for maintaining good reception sensitivity are included in the antenna device.
The installation position of the communication terminal device can be freely determined.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram illustrating an embodiment of a wireless communication system according to the present invention.

FIG. 2 is a circuit connection diagram showing a specific example of a distribution circuit in the circuit block diagram of FIG.

FIG. 3 is a circuit connection diagram showing a specific example of a superposition circuit in the circuit block diagram of FIG. 1;

FIG. 4 is a circuit block diagram showing another embodiment of the wireless communication system according to the present invention.

FIG. 5 is a circuit connection diagram showing another configuration of a transmission / reception switching circuit portion in the circuit block diagram of FIG. 1;

FIG. 6 is a circuit connection diagram showing still another configuration of the transmission / reception switching circuit portion in the circuit block diagram of FIG. 1;

FIG. 7 is a circuit block diagram showing a switching reception part in a conventional CS receiver.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Antenna device 11 Antenna element 12 First changeover switch 12a Input terminal 12b, 12c, 13b, 13c Changeover terminal 12d, 12e, 13d, 13e, 15a, 16a Control terminal 13 Second changeover switch 13a Output terminal 14 Distribution circuit 15 Low noise Amplifier 15b, 16b Transmission line 16 Power amplifier 17 Control signal generation circuit 18 Constant voltage circuit 19 Inverter circuit 20 Communication terminal device 21 Transmission / reception signal processing circuit 22 Superposition circuit 23 Voltage control circuit 24 DC power supply 30 Coaxial cable

Claims (12)

[Claims] 1. A wireless communication system in which a communication terminal device and an antenna device are connected by a single cable, the communication terminal device comprising: a power supply for supplying DC power; A transmission / reception signal processing circuit for outputting and generating a transmission / reception switching signal, and converting the power supplied from the power source into a first voltage signal or a second voltage signal having different voltage values based on the transmission / reception switching signal and outputting And a superimposing circuit for transmitting the reception signal to the transmission / reception signal processing circuit and transmitting the transmission signal and the voltage signal of the first voltage signal or the second voltage signal via the cable. An antenna device that transmits and receives the radio wave to the superimposing circuit via the cable, and transmits the received signal to the superimposing circuit via the cable; A distribution circuit that separates the transmission signal and the voltage signal that are input to the control circuit, a control signal generation circuit that generates a control signal based on the voltage value of the voltage signal, a reception circuit that operates when receiving the radio wave, and the radio wave A first switch circuit and a second switch circuit that switch and connect the reception circuit or the transmission circuit to the antenna element and the distribution circuit according to the control signal, and the voltage signal A wireless communication system comprising: a constant voltage circuit that converts the power into a voltage value and drives the antenna device. 2. The control signal generation circuit has a threshold value for an input voltage, and generates a different control signal based on whether a voltage value of the input voltage signal is higher or lower than the threshold value. The first switch circuit and the second switch circuit switch and connect the receiving circuit to the antenna element and the distribution circuit when the one control signal is input, and perform the transmission when the other control signal is input. A circuit connected to the antenna element and the distribution circuit, wherein the voltage control circuit includes a first voltage signal having a voltage value higher than the threshold value of the control signal generating circuit and a second voltage signal having a voltage value lower than the threshold value. The wireless communication system according to claim 1, wherein the signal is supplied alternatively. 3. The control signal generation circuit includes a first threshold value and a second threshold value having a voltage value lower than the first threshold value, and the second signal level lower than the second threshold value. 3. The method according to claim 2, wherein a first control signal is generated when a voltage signal is input, and a second control signal is generated when the first voltage signal higher than the first threshold value is input. Wireless communication system. 4. The control signal of the control signal generating circuit includes a first control signal or a second control signal having a lower voltage value than the first control signal, and the one control signal is a signal of the first switch. Circuit and the second switch circuit, for energizing and controlling the receiving circuit or the transmitting circuit, and the other control signal is switched off by the first switch circuit and the second switch circuit. The wireless communication system according to claim 1, wherein the transmission circuit or the reception circuit is deenergized. 5. The first switch circuit and the second switch circuit, a first control terminal for switchingly connecting the reception circuit to the antenna element and the distribution circuit, and a transmission circuit for transmitting the transmission circuit to the antenna element and the distribution circuit. A control signal generating circuit for selectively generating a first control signal and a second control signal and inputting the one control signal directly to the first control terminal. The wireless communication system according to any one of claims 1 to 4, wherein the signal is input to the second control terminal via an inverter circuit. 6. The reception circuit and the transmission circuit each include a control terminal, and input one of the first control signal and the second control signal to a control terminal of the reception circuit, and 6. An operation of the transmission circuit, wherein the operation of the transmission circuit is controlled by inputting a signal to a control terminal of the transmission circuit via an inverter circuit.
A wireless communication system according to claim 1. 7. The reception circuit according to claim 1, wherein at least one of the reception circuit and the transmission circuit includes an amplifier for amplifying a signal, and the amplifier receives power supply from the constant voltage circuit. 7. The wireless communication system according to any one of 6. 8. An antenna element for transmitting and receiving a radio wave, a distribution circuit for transmitting a reception signal to a communication terminal device and separating a voltage signal including a transmission signal and a control signal input from the communication terminal device, and the voltage signal A control signal generation circuit that generates a reception or transmission control signal based on the voltage value of
A reception circuit that operates when receiving the radio wave and a transmission circuit that operates when transmitting the radio wave; and the reception circuit is switched between the antenna element and the distribution circuit by the reception control signal, and the transmission is performed. A first switch circuit and a second switch circuit for switching and connecting the transmission circuit according to the control signal, and driving the power consumption circuit including the reception circuit and the transmission circuit by converting the voltage signal to power of a predetermined voltage value And a constant voltage circuit. 9. The first switch circuit and the second switch circuit include a first switch terminal and a second switch terminal,
Connecting the receiving circuit between the first switching terminals;
The transmission circuit is connected between switching terminals, and a first control terminal and a second control terminal for inputting the reception or transmission control signal are provided. The first switch circuit has an input terminal for connecting the antenna element. The antenna device according to claim 8, wherein the second switch circuit has an output terminal for connecting the distribution circuit. 10. An inverter circuit for converting one of the reception or transmission control signals into the other of the reception or transmission control signals is connected between the second control terminal and the control signal generation circuit. The antenna device according to claim 9, wherein 11. The receiving circuit comprises a low noise amplifier having a control terminal for inputting the control signal, and the transmitting circuit comprises a power amplifier having a control terminal for inputting the control signal. The antenna device according to claim 8, wherein the antenna device is an antenna device. 12. A DC power supply for supplying DC power, a transmission / reception processing a reception signal input from the antenna device, outputting a transmission signal to be transmitted to the antenna device, and controlling a transmission / reception switching operation in the antenna device. A transmission / reception signal processing circuit for generating a switching signal, and a voltage for converting the power supplied from the DC power supply into a first voltage signal or a second voltage signal having different voltage values based on the transmission / reception switching signal, and outputting the converted signal. A control circuit, and a superimposing circuit for transmitting the reception signal to the transmission / reception signal processing circuit and transmitting the transmission signal and the voltage signal of the first voltage signal or the second voltage signal via a cable. Characteristic communication terminal device.