WO2020090506A1

WO2020090506A1 - Communication device

Info

Publication number: WO2020090506A1
Application number: PCT/JP2019/041018
Authority: WO
Inventors: 弘紀榊原
Original assignee: 株式会社オートネットワーク技術研究所; 住友電装株式会社; 住友電気工業株式会社
Priority date: 2018-11-02
Filing date: 2019-10-18
Publication date: 2020-05-07
Also published as: JP2020072444A

Abstract

Two carrier frequencies are used at which one antenna can transmit or receive, and it is determined whether or not there is a wireless relay. An LF transmission circuit transmits an LF signal. A UHF signal is received for example as a response to the LF signal. A first strength specifying circuit specifies the strength T1 of a component of one carrier frequency of the UHF signal. A second strength specifying circuit specifies the strength T2 of a component of a frequency generated by third-order intermodulation distortion between the multiple carrier frequencies of the UHF signal. A control unit makes a determination about whether or not the difference in strength (T1-T2) is greater than or equal to a prescribed threshold value, and, assuming at least that said determination is positive, performs control of a vehicle-mounted device group.

Description

Communication device

The present disclosure relates to communication devices.

An authentication system (system) that performs bidirectional wireless communication between an in-vehicle device and a portable device and collates a code is known. The authentication system makes it possible to control a vehicle equipped with an in-vehicle device, for example, lock and unlock a vehicle door, and start an engine, provided that the verification is established.

▽ Of the wireless communication, the spatial range in which communication from the in-vehicle device to the portable device (tentatively referred to as "first communication" below) is possible is limited to the vicinity of the vehicle. Due to this limitation, the authentication system can be used only when the portable device is located near the vehicle.

The technology (tentatively referred to as "keyless control" below) that restricts vehicle control on the condition that a code is collated using wireless communication that limits the spatial range is This is advantageous from the viewpoint of avoiding that a person who does not own the aircraft gets into the vehicle and controls the vehicle.

It is pointed out that there is a technology commonly known as relay attack as a technology for controlling a vehicle against keyless control. In the relay attack, the authentication system can be performed even if the vehicle and the portable device are out of the above-mentioned near field by interposing the wireless relay used for the first communication between the vehicle and the portable device.

In the authentication system, the spatial range in which communication from the mobile device to the in-vehicle device (hereinafter tentatively referred to as "second communication") is usually set wider than the spatial range in which the first communication is possible. Therefore, the relay attack makes it possible to collate the codes and control the vehicle even if the in-vehicle device and the portable device are separated from each other. Relay attacks allow the vehicle to be controlled by someone who does not have a handheld device, and thus can be used to steal the vehicle.

Japanese Patent Laid-Open No. 2018-40133

Patent Document 1 proposes a technique for transmitting a predetermined signal by using two different carrier frequencies (hereinafter, tentatively referred to as "frequency") in the first communication. When the signal is relayed by the wireless relay device, the signal is amplified to generate third-order intermodulation distortion with respect to the frequency. By this generation, the wireless repeater transmits to the portable device a signal having not only the frequency but also the frequency generated by the third-order intermodulation distortion (hereinafter, "intermodulation frequency"). The portable device detects the component of the intermodulation frequency in the signal, and based on the intensity of the component, it is determined whether or not there is relay by the wireless relay device.

Since the first communication usually uses a frequency in the LF (Low Frequency) band (for example, 30 kHz to 300 kHz), the bandwidth adopted by the first communication is narrow. In the technology introduced in Patent Document 1, by using the counter frequency in the first communication, the number of antennas used in the first communication is twice as compared with the case where one frequency is used in the first communication. Becomes Therefore, the technique introduced in Patent Document 1 is disadvantageous in view of cost.

Therefore, the present disclosure aims to provide a technique of determining whether or not there is a wireless relay by using two carrier frequencies that can be transmitted or received by one antenna.

A first aspect of the communication device of the present disclosure is a communication device that receives a second signal in the UHF band transmitted in response to the first signal by the second communication device. The second signal has a plurality of carrier frequencies. The communication device includes a transmission circuit, an intensity specifying circuit, and a control unit. The transmission circuit transmits the first signal. The intensity specifying circuit includes a first intensity, which is an intensity of a component of the carrier frequency of the second signal, and a component of a frequency generated by third-order intermodulation distortion of the plurality of carrier frequencies of the second signal. The second intensity, which is the intensity, is specified. The control unit determines whether or not the difference between the first intensity and the second intensity is equal to or more than a predetermined threshold value, and at least the determination is positive, the control to the control target is performed. I do.

A second aspect of the communication device of the present disclosure is a communication device that transmits a second signal in the UHF (Ultra High Frequency) band in response to the first signal. The communication device includes a receiving circuit, a transmission processing circuit, and a mixer. The receiving circuit receives the first signal. The transmission processing circuit modulates a plurality of carrier frequencies to generate a plurality of modulated waves containing information. The mixer combines the plurality of modulated waves to generate the second signal.

The present disclosure can be realized not only as a communication apparatus including such a characteristic processing unit, but also as a communication method having such characteristic processing as a step, or such a step as a computer (step). It can be realized as a program to be executed by a computer. Further, it can be realized as a semiconductor integrated circuit that realizes a part or all of the communication device or a communication system including the communication device.

Each of the communication devices according to the first aspect and the second aspect of the present disclosure contributes to a technique for determining whether or not there is a wireless relay using two carrier frequencies that can be transmitted or received by one antenna.

FIG. 1 is a schematic view illustrating a position where two communication devices adopted in this embodiment are arranged. FIG. 2 is a block diagram illustrating the configuration of the first communication device. FIG. 3 is a block diagram illustrating the configuration of the second communication device. FIG. 4 is a flowchart showing an operation adopted in the authentication in the first communication device. FIG. 5 is a flowchart showing the operation adopted in the authentication in the second communication device. FIG. 6 is a graph showing the spectrum of the modulated wave.

[Description of Embodiments of the Present Disclosure]
First, embodiments of the present disclosure will be listed and described.
(1) A first aspect of the present disclosure is a communication device that receives a second signal in the UHF band transmitted in response to the first signal by the second communication device. The second signal has a plurality of carrier frequencies. The communication device includes a transmission circuit, an intensity specifying circuit, and a control unit. The transmission circuit transmits the first signal. The intensity specifying circuit includes a first intensity, which is an intensity of a component of the carrier frequency of the second signal, and a component of a frequency generated by third-order intermodulation distortion of the plurality of carrier frequencies of the second signal. The second intensity, which is the intensity, is specified. The control unit determines whether or not the difference between the first intensity and the second intensity is equal to or more than a predetermined threshold value, and at least the determination is positive, the control to the control target is performed. I do.

According to the first aspect of the present disclosure, reception can be performed using two carrier frequencies with one antenna, and the presence or absence of wireless relay can be determined based on the determination result by the control unit.

(2) The control unit stores at least one authentication code, and the control unit presupposes that an authentication code corresponding to any one of the authentication codes is included in the second signal. It is preferable to perform the control. This is because the verification using the authentication code is performed.

(3) A second aspect of the present disclosure is a communication device that transmits a second signal in the UHF band in response to the first signal. The communication device includes a receiving circuit, a transmission processing circuit, and a mixer. The receiving circuit receives the first signal. The transmission processing circuit modulates a plurality of carrier frequencies to generate a plurality of modulated waves containing information. The mixer combines the plurality of modulated waves to generate the second signal.

According to the second aspect of the present disclosure, it is possible to perform transmission by using two carrier frequencies with one antenna, which contributes to determining whether or not there is wireless relay.

(4) The communication device further includes a control unit, the control unit stores at least one authentication code, and on the assumption that an authentication code corresponding to any one of the authentication codes is included in the first signal, It is preferable to cause the transmission processing circuit to generate the plurality of modulated waves. This is because the verification using the authentication code is performed.

[Details of the embodiment of the present disclosure]
Specific examples of the communication device of the present disclosure will be described below with reference to the drawings. It should be noted that the present disclosure is not limited to these exemplifications, and is indicated by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope. At least some of the embodiments described below may be arbitrarily combined.

<Structure>
FIG. 1 is a schematic diagram illustrating a position where two communication devices adopted in this embodiment are arranged. The first communication device 1 is mounted on the vehicle body 9. The first communication device 1 includes a main body 10, a transmission antenna 107, and a reception antenna 108. The main body 10 is applied to a body control module (hereinafter also referred to as “BCM”) which is an in-vehicle device, for example. The second communication device 2 is provided in, for example, a portable device called fob or FOB.

The transmitting antenna 107 and the receiving antenna 108 are usually provided outside the main body 10. In FIG. 1, the transmitting antenna 107 and the receiving antenna 108 are located near the left front door and near the left rear door, respectively, by using black triangle symbols. Of course, the transmitting antenna 107 and the receiving antenna 108 may be arranged at positions other than the positions described above. The case where the second communication device 2 is located outside the vehicle body 9 is exemplified.

A signal in the LF band (hereinafter also referred to as “LF signal”) K11 is transmitted from the transmitting antenna 107 as the first communication. The receiving antenna 108 receives a signal in the UHF band (0.3 to 3 GHz) (hereinafter also referred to as “UHF signal”) as the second communication. Here, the case where the first communication device 1 transmits the LF signal K11 from the transmission antenna 107 as the first communication and receives the UHF signal K13 from the reception antenna 108 as the second communication is illustrated.

However, in FIG. 1, a case where the UHF signal K23 is transmitted from the second communication device 2 and the signal K23 is received as the UHF signal K13 in the first communication device 1 is illustrated. Similarly, FIG. 1 illustrates a case where the LF signal K11 transmitted from the first communication device 1 is received as the LF signal K12 by the second communication device 2. In FIG. 1, symbols enclosed by parentheses indicate signals viewed from the receiving side, and symbols before the parentheses indicate signals viewed from the transmitting side.

FIG. 2 is a block diagram illustrating a configuration of the first communication device 1. The main body 10 includes a UHF receiving circuit 100, a first strength specifying circuit 101, a second strength specifying circuit 102, a comparison calculation unit 103, an LF transmission circuit 104, and a control unit 105.

The control unit 105 controls various in-vehicle devices. In FIG. 2, a plurality of in-vehicle devices are collectively illustrated as an in-vehicle device group 106. The in-vehicle device group 106 is a control target to be controlled by the control unit 105. For example, the in-vehicle device group 106 includes a door lock device that controls to lock / unlock the door and an engine control device that controls the engine. The control unit 105 is realized by, for example, a microcomputer included in the first communication device 1.

The LF transmission circuit 104 receives the information J11 from the control unit 105, generates the LF signal K11 including the information J11, and transmits the LF signal K11 via the transmission antenna 107. The UHF receiving circuit 100 receives the UHF signal K13 via the receiving antenna 108 and extracts the information J10 included in the UHF signal K13. The control unit 105 generates information J11 to be included in the LF signal K11 and collates the authentication code included in the information J10.

For example, the control unit 105 stores at least one authentication code. The authentication code is information used to identify the first communication device 1 itself or the second communication device 2, for example. The information J10 and J11 includes at least one of the authentication codes. For example, the authentication code identifies the source that sends the signal in which it is included. The authentication code included in the information J11 indicates that the transmission source that transmits the LF signal K11 is the first communication device 1.

The control unit 105 compares the authentication code included in the information J10 with the authentication code stored in itself, and determines whether or not the UHF signal K13 is transmitted from an expected transmission source.

The comparison calculation unit 103 calculates the intensities T1 and T2 of the components of the UHF signal K13 at a pair of different frequencies, and also compares the two. The result of this comparison is transmitted to the control unit 105. The strengths T1 and T2 are specified by the first strength specifying circuit 101 and the second strength specifying circuit 102, respectively. Identifying the specific frequencies and intensities mentioned above will be detailed later.

FIG. 3 is a block diagram illustrating the configuration of the second communication device 2 in this embodiment. The second communication device 2 is configured to be capable of bidirectionally communicating with the first communication device 1. For example, the second communication device 2 is applied to a portable device adopted for keyless control. When applied in this way, the second communication device 2 may be referred to as a fob (or FOB).

The second communication device 2 includes a reception antenna 207, a transmission antenna 208, a first transmission processing circuit 201, a second transmission processing circuit 202, a mixer 203, an LF reception circuit 204, and a control unit 205. ..

The LF receiving circuit 204 receives the LF signal K12 via the receiving antenna 207 and extracts the information J12 included in the LF signal K12. The control unit 205 stores at least one authentication code. The control unit 205 also collates the authentication code included in the information J12 with the authentication code stored in itself.

When the LF signal K11 transmitted from the first communication device 1 is received by the second communication device 2 as the LF signal K12 (see FIG. 1), the information J12 includes the information J11. At this time, it is determined that the transmission source of the LF signal K12 received by the second communication device 2 is the first communication device 1 by collation using the authentication code included in the information J12.

The first transmission processing circuit 201 receives the information J20 from the control unit 205 and generates the UHF signal K21 including the information J20. The second transmission processing circuit 202 receives the information J20 from the control unit 205 and generates a UHF signal K22 including the information J20.

The mixer 203 synthesizes the UHF signals K21 and K22 to generate the UHF signal K23. The UHF signal K23 is transmitted from the transmitting antenna 208 and used for the second communication. The control unit 205 also generates the information J20 including the authentication code. For example, the authentication code included in the information J20 indicates that the transmission source that transmits the UHF signal K23 is the second communication device 2. When the UHF signal K23 transmitted from the second communication device 2 is received by the first communication device 1 as the UHF signal K13 (see FIG. 1), the information J10 includes the information J20. At this time, it is determined that the transmission source of the UHF signal K13 received by the first communication device 1 is the second communication device 2 by collation using the authentication code included in the information J10.

The receiving antenna 207 and the transmitting antenna 208 are normally provided inside the second communication device 2. The control unit 205 is realized by, for example, a microcomputer included in the second communication device 2.

FIG. 4 is a flowchart showing an operation adopted in the authentication in the first communication device 1 (hereinafter also referred to as “authentication operation”). FIG. 5 is a flowchart showing the authentication operation in the second communication device 2. In the authentication operation, the first communication device 1 first transmits the LF signal K11 in step S101 (see FIG. 4). Specifically, using the information J11 generated by the control unit 105, the LF signal K11 is generated in the LF transmission circuit 104 and transmitted via the transmission antenna 107.

In the authentication operation, the second communication device 2 first starts the reception process in step S21 (see FIG. 5). Specifically, the LF receiving circuit 204 can receive the LF signal K12 via the receiving antenna 207. Then, in step S22, it is determined whether the second communication device 2 has received the LF signal K12. Such a determination is specifically realized by using, for example, a determination as to whether or not an LF signal from which the LF receiving circuit 204 can extract the information J12 has been received.

If the result obtained in the determination in step S22 is affirmative (that is, if it is determined that the LF signal K12 is received; if it is determined that the LF signal capable of extracting the information J12 is received), then step S23 is executed. To be done. If the result obtained in the determination in step S22 is negative, the authentication operation is temporarily terminated. The authentication operation may be repeatedly executed, or step S22 may be repeatedly executed until the result obtained by the determination in step S22 becomes positive.

In step S23, the information J12 extracted from the LF signal K12 includes an authentication code, and the authentication code corresponds to any of the authentication codes stored in the control unit 205 (for example, a predetermined encryption / decryption for the information J12 / It is determined whether the decrypted information matches the authentication code). In other words, it is determined whether or not the information J12, and by extension, the LF signal K12 includes the authentication code corresponding to any of the authentication codes stored in the control unit 205. In FIG. 5, such a determination is simply abbreviated as “code matching established?”.

Assume, for example, that one of the authentication codes stored in the control unit 205 indicates that the first communication device 1 is the transmission source. At this time, if the LF signal K12 has been transmitted as the LF signal K11 from the first communication device 1, the authentication code included in the information J11 included in the information J12 corresponds to the authentication code stored in the control unit 205. To do. In such a case, the result obtained in the determination in step S23 is affirmative.

If the information J12 extracted from the LF signal K12 does not include the authentication code, or if the authentication code included in the information J12 does not correspond to any of the authentication codes stored in the control unit 205, it is determined in step S23. The result is negative. In this case, the authentication operation ends once. The authentication operation may be repeatedly executed, or steps S22 and S23 may be repeatedly executed until the result obtained by the determination in step S23 becomes positive.

If the result obtained in the determination in step S23 is affirmative, step S3 is executed. In step S3, UHF signals K21 and K22 are generated, and UHF signal K23 is transmitted from mixer 203 via transmitting antenna 208. As described above, the UHF signal K23 is obtained by synthesizing the UHF signals K21 and K22 by the mixer 203. Both UHF signals K21 and K22 include information J20.

For the second communication device 2, the UHF signal K23 is a response signal to the received LF signal K12. When the LF signal K11 is received by the second communication device 2 as the LF signal K12 and the UHF signal K23 is received by the first communication device 1 as the UHF signal K13, the UHF signal is received by the first communication device 1. K13 is a response signal to the transmitted LF signal K11.

When step S3 is executed, the authentication operation of the second communication device 2 ends once. As described above, the authentication operation may be repeatedly executed.

Step S3 is executed on condition that the result obtained in the determination in step S23 is affirmative. In other words, the control unit 205 assumes that the LF signal K12 includes an authentication code corresponding to any of the authentication codes stored in the control unit 205, and the first transmission processing circuit 201 and the second transmission processing circuit 201. The 202 is made to generate UHF signals K21 and K22. Specifically, for example, the information J20 is given to the first transmission processing circuit 201 and the second transmission processing circuit 202 only when the result obtained in the determination in step S23 is affirmative.

UHF signals K21 and K22 are modulated waves having carrier frequencies f4 and f5, respectively. For example, the UHF signals K21 and K22 are obtained by modulating carrier waves having carrier frequencies f4 and f5 by a predetermined modulation signal based on the information J20. In other words, the UHF signals K21 and K22 are modulated waves obtained by modulating different carrier frequencies f4 and f5, and both contain the information J20.

∙ Generally, an antenna adopted for transmitting a signal in the UHF band has a wide bandwidth. Therefore, the carrier frequencies f4 and f5 can be set to frequencies close to the one that can be transmitted by the single transmission antenna 208, and the UHF signal K23 can be transmitted via the transmission antenna 208. For example, the carrier frequencies f4 and f5 are selected to be 315 MHz and 317 MHz, respectively.

Referring to FIG. 4, after step S101 is executed, it is determined in step S102 whether or not first communication device 1 has received UHF signal K13. Such a determination is specifically realized by using, for example, a determination as to whether or not a UHF signal from which the UHF receiving circuit 100 can extract the information J10 has been received. For example, when the UHF signal K23 is received as the UHF signal K13, the UHF receiving circuit 100 separates the UHF signal K21 and extracts the information J10 including the information J20 included in the UHF signal K21.

The UHF signal K13 can be received by one receiving antenna 108 by setting the carrier frequencies f4 and f5 to frequencies close to the one that can be transmitted by one transmitting antenna 208 as described above.

If the result obtained in the determination in step S102 is affirmative (that is, if it is determined that the UHF signal K13 is received; if it is determined that the UHF signal capable of extracting the information J10 is received), then step S104 is executed. To be done. If the result obtained in the determination in step S102 is negative, it is determined in step S103 whether or not a predetermined time has elapsed since the execution of step S101.

If the result obtained by the determination in step S103 is negative, that is, if the predetermined time has not elapsed since the LF signal K11 was transmitted, step S102 is executed again. As described above, the steps S102 and S103 are repeatedly performed. That is, after the LF signal K11 is received as the LF signal K12 by the second communication device 2, the UHF signal K23 is generated as the response signal and the UHF signal K23 is generated. This is a process that considers the delay time until it is received as the UHF signal K13.

If the result obtained in the determination in step S103 is affirmative, that is, if the predetermined time has elapsed without receiving the UHF signal K13, the authentication operation in the first communication device 1 ends. This is because it is assumed that the LF signal K11 did not reach the second communication device 2 or that the second communication device 2 did not operate normally.

In step S104, the intensities T1 and T2 of the UHF signal K13 are specified. The intensity T1 is the intensity of the component of the carrier frequency f4 of the UHF signal K21 or the carrier frequency f5 of the UHF signal K22. The intensity T2 is the intensity of the intermodulation frequency component generated by the third-order intermodulation distortion resulting from the synthesis of the UHF signals K21 and K22 or the third-order intermodulation distortion resulting from the amplification of the UHF signals K21 and K22. Is. For example, the intermodulation frequency is represented by 2 * f4-f5, 2 * f5-f4 (the symbol "*" indicates multiplication).

FIG. 6 is a graph showing the spectrum of the modulated wave, specifically the spectrum of the UHF signal K13. However, it is exemplified that f4 <f5, the intensity T1 is the intensity of the component of the carrier frequency f4 of the UHF signal K13, and the intensity T2 is the intensity of the component of the intermodulation frequency 2 * f4-f5 of the UHF signal K13. To be done. According to the above example, the intensity T1 is the component of the UHF signal K13 at the frequency of 315 MHz, and the intensity T2 is the component of the UHF signal K13 at the frequency of 313 MHz.

As described above, the strengths T1 and T2 are specified by the first strength specifying circuit 101 and the second strength specifying circuit 102, respectively. Specifically, the first strength specifying circuit 101 and the second strength specifying circuit 102 can be realized by known filtering technology and signal strength measuring technology.

For example, the intensity T1 has a frequency filter (filter) that transmits the carrier frequency f4 and significantly attenuates the intermodulation frequencies 2 * f5-f4, 2 * f4-f5 and the carrier frequency f5, and a signal that has passed through the filter. It is realized by a variable amplifier (or variable attenuator) that amplifies (or attenuates) to the strength of. The intensity T1 is obtained from the gain of the variable amplifier or the attenuation amount of the variable attenuator.

Considering that the bandwidth of such a frequency filter in the UHF band is about 1 MHz, the carrier frequencies f4, f5 and the intermodulation frequencies 2 * f5-f4, 2 * f4-f5 are about 2 MHz or more with respect to each other. It is desirable to be separated. From this point of view, selecting 315 MHz and 317 MHz as the carrier frequencies f4 and f5, respectively, as described above, is one of the advantageous selections.

A wireless repeater used for the second communication is interposed between the first communication device 1 and the second communication device 2, and the UHF signal K23 is amplified by this wireless repeater to generate the first UHF signal K13 as a UHF signal K13. The intensity T2 when received by the communication device 1 is higher than the intensity T2 when the UHF signal K23 is received as the UHF signal K13 without being relayed by the first communication device 1 unless other conditions are different. ..

On the other hand, it is difficult to determine whether or not the UHF signal K23 was relayed by measuring only the strength T2. For example, it is obvious that the propagation loss until the UHF signal K23 transmitted from the second communication device 2 is received by the first communication device 1 as the UHF signal K13 affects the strength T2. The propagation loss is not calculated from the strength T2 itself.

On the other hand, strength T1 is also affected by the propagation loss, similar to strength T2. Therefore, in order to exclude the influence of this propagation loss on the strength T2, the difference in strength (T1-T2) is obtained, and when the difference in strength (T1-T2) is large, the UHF signal K23 is not relayed and the UHF signal K23 is not relayed. It is determined that it was received as K13, and if it is small, it is determined that it was relayed.

Specifically, in step S105, it is determined whether or not the strength difference (T1−T2) is equal to or larger than a predetermined threshold value Δ. The determination can be performed by the comparison calculation unit 103.

If the result obtained in the determination in step S105 is negative, that is, if the intensity difference (T1−T2) is less than the predetermined threshold Δ, the UHF signal K23 is relayed (subjected to a relay attack) and UHF is transmitted. Since it is assumed that the signal K13 has been received, the authentication operation in the first communication device 1 ends.

If the result obtained in the determination in step S105 is affirmative, that is, if the intensity difference (T1−T2) is greater than or equal to the predetermined threshold value Δ, the UHF signal K23 is not relayed (without a relay attack). ) Since it is assumed that it has been received as the UHF signal K13, the verification code is collated in step S106.

In step S106, the information J10 extracted from the UHF signal K13 includes an authentication code, and the authentication code corresponds to any of the authentication codes stored in the control unit 105 (for example, predetermined encryption / decryption for the information J10). It is determined whether or not the information subjected to is matched with the authentication code). In other words, it is determined whether or not the information J10, and thus the UHF signal K13, includes the authentication code corresponding to any of the authentication codes stored in the control unit 105. In FIG. 4, such a determination is simply abbreviated as “code matching established?”.

Assume, for example, that one of the authentication codes stored in the control unit 105 indicates that the second communication device 2 is the transmission source. At this time, if the UHF signal K13 has been transmitted as the UHF signal K23 from the second communication device 2, the authentication code included in the information J20 included in the information J10 corresponds to the authentication code stored in the control unit 105. To do. In such a case, the result obtained in the determination in step S106 is affirmative.

If the information J10 extracted from the UHF signal K13 does not include the authentication code, or if the authentication code included in the information J10 does not correspond to any of the authentication codes stored in the control unit 105, it is determined in step S106. The result is negative. In this case, the authentication operation ends.

If the result obtained in the determination in step S106 is affirmative, vehicle control is executed in step S107. Specifically, the vehicle control according to the instruction included in the information J20 included in the information J10 is realized by the operation of the in-vehicle device group 106 in the control by the control unit 105. For example, when the information J20 includes an instruction to unlock the door of the vehicle body 9, the door is unlocked in step S107.

Step S107 is executed only when both the result obtained in the determination in step S105 and the result obtained in the determination in step S106 are positive. That is, steps S105 and S106 are one of the preconditions for the control unit 105 to perform the control in step S107.

In this way, the first communication device 1 can determine whether or not there is a wireless relay device with the second communication device 2 by performing the comparison calculation using the intensities T1 and T2. The second communication device 2 contributes to determine whether or not there is a wireless repeater by transmitting the UHF signal K23 obtained by combining the UHF signals K21 and K22.

The UHF signal K23 can be transmitted by one transmitting antenna 208, and the UHF signal K13 can be received by one receiving antenna 108.

<Additional notes>
{Modification}
In the flowchart shown in FIG. 4, the order of steps S105 and S106 may be exchanged.

The strength T1 may be the strength of the component of the carrier frequency f5, and the strength T2 may be the strength of the component of the intermodulation frequency 2 * f5-f4.

The UHF signal K23 may be obtained by combining three or more UHF signals. That is, the UHF signal K23 only needs to have a plurality of carrier frequencies.

The first strength specifying circuit 101 and the second strength specifying circuit 102 may be collectively considered as a strength specifying circuit. The first transmission processing circuit 201 and the second transmission processing circuit 202 may be collectively considered as a transmission processing circuit.

The control unit 105 may include the comparison calculation unit 103. The comparison calculation unit 103 may be realized as a calculation performed by the microcomputer together with the control unit 105.

Each component of the communication device includes a computer including a microprocessor (micro processor), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. An arithmetic processing unit such as a microprocessor reads a computer program including some or all of the steps of the flowcharts shown in FIGS. 4 to 5 from a storage unit such as a ROM or a RAM and executes the computer program.

The computer programs of these plural components can be installed from an external server device or the like. Further, such computer programs are in a state of being respectively stored in a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Memory), and a semiconductor memory (memory). Distribute.

The respective configurations described in the above-described embodiments and modifications can be appropriately combined unless they contradict each other.

DESCRIPTION OF SYMBOLS 1 1st communication apparatus 2 2nd communication apparatus 9 Vehicle body 10 Main body 100 UHF reception circuit 101 1st intensity | strength specific circuit 102 2nd intensity | strength specific circuit 103 Comparison calculation part 104 LF transmission circuit 105,205 Control part 106

Vehicle equipment group

107 , 208

transmission antenna

108, 207 reception antenna 201 first transmission processing circuit 202 second transmission processing circuit 203 mixer 204 LF reception circuit J10, J11, J12, J20 information K11, K12 LF signal K13, K21, K22, K23 UHF signal S101, S102, S103, S104, S105, S106, S107, S21, S22, S23, S3 Steps T1, T2 Strength f4, f5 Carrier frequency Δ Threshold

Claims

A communication device for receiving a second signal in the UHF band transmitted in response to the first signal by the second communication device,
The second signal has a plurality of carrier frequencies,
The communication device includes a transmission circuit, an intensity specifying circuit, and a control unit,
The transmitter circuit transmits the first signal,
The intensity specifying circuit includes a first intensity, which is an intensity of a component of the carrier frequency of the second signal, and a component of a frequency generated by third-order intermodulation distortion of the plurality of carrier frequencies of the second signal. Specify the second strength, which is the strength,
The control unit determines whether a difference between the first intensity and the second intensity is equal to or more than a predetermined threshold value, and at least controls the control target on the premise that the determination is affirmative. Do, communication equipment.
The communication device according to claim 1,
The control unit stores at least one authentication code,
The said control part is a communication apparatus which performs the said control to the said control object on the assumption that the authentication code corresponding to either of the said authentication code is contained in the said 2nd signal.
A communication device for transmitting a second signal in the UHF band in response to a first signal,
A receiving circuit, a transmission processing circuit, and a mixer,
The receiving circuit receives the first signal,
The transmission processing circuit, a plurality of carrier frequencies are respectively modulated, to generate a plurality of modulated waves containing information,
The communication device, wherein the mixer combines the plurality of modulated waves to generate the second signal.
The communication device according to claim 3, wherein
Further provided with a control unit,
The control section stores at least one authentication code and causes the transmission processing circuit to generate the plurality of modulated waves on the assumption that an authentication code corresponding to any one of the authentication codes is included in the first signal. ,Communication device.