JP5221491B2 - Electronic key system repeater use fraud prevention device - Google Patents

Description

  The present invention relates to an electronic key system that wirelessly performs ID verification between an electronic key and an object to be communicated with the key, and more specifically, radio waves transmitted and received by the system are exchanged by a repeater to illegally establish ID verification. The present invention relates to a device for preventing fraudulent use of a repeater.

  2. Description of the Related Art Conventionally, many vehicles use an electronic key system (see Patent Document 1 or the like) that uses an electronic key that can transmit an ID code wirelessly as a vehicle key, and performs ID verification wirelessly with the vehicle using this electronic key. Has been. In this type of electronic key system, when an electronic key receives a request transmitted from a vehicle, the electronic key automatically returns an ID code to the vehicle in response to the request, and performs an ID verification. There is. In the key operation free system, door lock / unlock is permitted or executed when ID verification is established outside the vehicle, and engine start operation is permitted when ID verification is performed inside the vehicle.

JP 2005-262915 A JP 2006-161545 A

  By the way, in such an electronic key system, a fraudulent act using a repeater (see a fraudulent act using a repeater: refer to Patent Document 2, etc.) as a fraudulent act intended to establish ID verification without regard to the user's intention. There is. For example, when the electronic key is located at a location far from the vehicle, the repeater use fraudulent act is an act of establishing a communication between these two parties by connecting the electronic key to the vehicle by a plurality of repeaters and relaying radio waves. is there. Therefore, since ID verification is established without permission of the user, there is a problem that the door is unlocked or the engine is started without permission by the theft agent.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a repeater use fraud prevention device for an electronic key system that can detect a fraud using a repeater and ensure crime prevention against theft.

  In order to solve the above problem, in the present invention, an ID reply request is transmitted from the key communication target, ID collation is performed with an ID code returned from the electronic key in response to the request, and the electronic key and the electronic key When the key communication target performs mutual communication according to the ID collation, the radio wave is modulated and transmitted from one to the other, and when the other receives the radio wave, the radio wave is acquired by envelope detection, and the envelope is obtained. Measuring means for measuring the time required for the amplitude of one pulse of the received envelope to take a reference value in a repeater-use fraud prevention apparatus of an electronic key system that acquires the signal content of the radio wave from the signal waveform of the line Determining means for determining whether or not the measurement time of the measurement means coincides with a comparison time taken in communication according to regular communication; and the measurement time is different from the comparison time. When taking a value, and summarized in that and a termination means to kill or limit the communication of the ID verification.

  According to this configuration, when attempting to establish communication illegally by, for example, an illegal act of using a repeater, there is a high possibility that the repeater cannot accurately transmit radio waves until the waveform rises or falls. Therefore, in the case of this configuration, by measuring the time required for the amplitude of one pulse of the received radio wave to take the reference value and checking whether the measurement time matches the comparison time that can be regarded as regular communication, It is determined whether the communication is regular communication. If the measurement time matches the comparison time, the communication is processed as normal communication and the communication is continued. If the measurement time does not match the comparison time, the communication is invalid and the communication is forcibly terminated. Or restrict. For this reason, it becomes possible to make it difficult to establish an unauthorized communication due to an illegal act of using the repeater.

  In the present invention, in the mutual communication, at least one of the forward communication and the backward communication is executed by amplitude modulation, and the measurement means, the determination means, and the termination means are the amplitude modulation of the electronic key and the key communication target. The main point is that it is provided on the radio wave receiving side.

  According to this configuration, the radio wave conforming to amplitude modulation has the same rising or falling edge when the binary data is switched between “0” and “1”, regardless of the signal content. Take. For this reason, if measurement means, judgment means, and termination means are provided on the amplitude modulation radio wave reception side and the measurement time is measured with radio waves according to amplitude modulation, measurement is possible even when the signal content is different. It is possible to obtain the time accurately, and thus it is possible to more accurately determine whether or not the communication partner is a regular partner.

The gist of the present invention is that the measurement means, the determination means, and the end means are provided in the electronic key.
According to this configuration, for example, in the case where the key communication partner triggers the electronic key to perform communication as mutual communication, and the mutual communication is determined to be unauthorized communication, the electronic key transmits the radio wave from the key communication partner. Communication can be forcibly terminated or restricted at the time of acceptance. Therefore, it is possible to forcibly terminate or limit communication at an early stage of returning communication.

The gist of the present invention is that the reference value is a maximum reception value that can be taken at a maximum when the one pulse of the envelope is received.
According to this configuration, even if the reception strength of the radio wave changes, if the measurement time is calculated using the reference value as the maximum reception value, the reception strength is reduced on the condition that the frequency of the reception radio wave is the same. It is possible to set the same value before and after the change. Therefore, it is possible to acquire the correct measurement time even if the radio wave reception intensity changes.

The gist of the present invention is that a notification means for notifying that when the measurement time takes a value different from the comparison time is provided.
According to this configuration, when the measurement time takes a value different from the comparison time, that is, when the communication is not regular communication, it is possible to notify the surroundings and the user by the notification means. It becomes possible to make it higher.

  ADVANTAGE OF THE INVENTION According to this invention, the fraudulent act using a repeater can be detected and the crime prevention property with respect to a theft can be ensured.

The block diagram which shows schematic structure of the key operation free system in one Embodiment. The schematic diagram explaining the outline | summary of the fraud using a repeater. The block diagram which shows schematic structure of the repeater use fraud prevention apparatus. The wave form diagram which shows the received electric wave when smart communication is regular communication. The wave form diagram which shows the received radio wave waveform when smart communication is communication by the fraudulent use of the repeater. The wave form diagram which shows the received radio wave waveform when smart communication is communication by the fraudulent use of the repeater. The waveform diagram of the envelope which shows the outline of amplitude modulation. The wave form diagram of the received radio wave which shows an example of the regular communication confirmation process in another example. The wave form diagram of the received radio wave which shows an example of the regular communication confirmation process in another example.

Hereinafter, an embodiment of a repeater use fraud prevention apparatus of an electronic key system embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, the vehicle 1 is provided with a key operation free system 3 that automatically executes ID (Identification) verification when the electronic key 2 approaches the vehicle 1. This key operation free system 3 includes a smart entry system in which a door lock is unlocked and unlocked in a series of door opening and closing operations without actually performing a key operation, and a push type engine installed in the vehicle. There is a one-push engine start system that can start the engine only by pressing the switch 4. The vehicle 1 corresponds to a key communication target, and the key operation free system 3 corresponds to an electronic key system.

  In this case, the vehicle 1 includes a key verification device 5 that performs ID verification with the electronic key 2, a door lock device 6 that manages a door lock operation, and an engine start device 7 that manages the operation of the engine. These are provided and connected by an in-vehicle bus 8. The key verification device 5 is provided with a verification ECU (Electronic Control Unit) 9 as a control unit of the device 5. In the memory (not shown) of the verification ECU 9, the ID code of the electronic key 2 that forms a pair with the vehicle 1 is registered. The verification ECU 9 receives an out-of-vehicle transmitter 10 that transmits LF (Low Frequency) band radio waves outside the vehicle, an in-vehicle transmitter 11 that transmits LF band radio waves into the car, and UHF (Ultra High Frequency) band radio waves. The vehicle tuner 12 is connected. The vehicle transmitter 10 and the vehicle transmitter 11 transmit a request signal Srq as an ID transmission request (request) to the electronic key 2 by LF band radio waves, and attempt to establish so-called smart communication.

  On the other hand, the electronic key 2 is provided with a communication control unit 13 that performs overall control of the operation of the electronic key 2. An ID code is registered in the memory (not shown) of the communication control unit 13 as an ID unique to the key. The communication control unit 13 is connected to an LF receiver 14 capable of receiving LF band radio waves and a UHF transmitter 15 capable of transmitting UHF band radio waves.

  When the electronic key 2 is located outside the vehicle, the request signal Srq is intermittently transmitted from the vehicle transmitter 10. At this time, when the electronic key 2 enters the outside communication area of the request signal Srq, the electronic key 2 responds to the request signal Srq and returns an ID signal Sid with a radio wave in the UHF band. The ID signal Sid includes the ID code of the electronic key 2. When the vehicle tuner 12 receives the ID signal Sid and the smart communication outside the vehicle (external communication) is established, the verification ECU 9 executes external verification as ID verification (smart verification). And if this outside vehicle collation is materialized, door lock locking / unlocking by the door lock device 6 is permitted or executed.

  Further, when it is detected by a courtesy switch or the like that the driver gets on, for example, the in-vehicle transmitter 11 starts transmitting the request signal Srq instead of the out-of-vehicle transmitter 10. At this time, when smart communication (in-vehicle communication) is established by entering the in-vehicle communication area of the in-vehicle transmitter 11, the verification ECU 9 executes in-vehicle verification as ID verification (smart verification). And if this in-vehicle collation is materialized, the power supply transition operation and engine starting operation by the engine switch 4 (engine starting device 7) will be permitted.

  By the way, as shown in FIG. 2, as a kind of vehicle theft, there is a fraudulent act of using a repeater. For example, when the electronic key 2 is located outside the outside communication area, the repeater 16 is placed in the outside communication area, and the vehicle 1 is connected to the outside electronic key 2 by the repeater 16. This is an act of establishing ID verification. If you receive a theft act due to fraudulent use of the repeater, ID verification will be established without permission from the user, leading to the possibility that the door lock may be unlocked or the engine may be started by the theft person .

  Therefore, as shown in FIG. 3, the key operation free system 3 of the present example is provided with a repeater use fraud prevention device 17 that prevents the establishment of unauthorized smart communication using the repeater 16. As shown in FIGS. 4 to 6, the repeater use fraud prevention apparatus 17 of this example is a time until the reception radio wave of the electronic key 2 reaches the maximum reception value Vmax that can be taken at the time of reception (hereinafter referred to as measurement). It is determined whether or not the smart communication is regular communication by measuring whether or not the measurement time Tx takes the comparison time Tk set as an ideal value.

  By the way, in mutual communication of smart collation, AM modulation (amplitude modulation) is used for forward communication in which radio waves are transmitted from the vehicle 1 to the electronic key 2. As shown in FIG. 7, the AM modulation expresses, for example, a waveform group having the same amplitude in the transmission radio wave waveform 18 as “1” of binary data, and a period in which the amplitude is 0 as “0” of binary data. In other words, this is a modulation method in which the communication control unit 13 receives the envelope 19 connecting the vertices of the radio wave waveform 18 as binary data “0” and “1”, that is, a pulse signal. The communication control unit 13 acquires the data content of the radio wave by envelope detection that reads the combination of “0” and “1” of the envelope 19.

  If the smart communication is normally executed, the received radio wave waveform 20 of the electronic key 2, that is, one pulse P of the envelope 19 rises in accordance with the normal slew rate (slope), as shown in FIG. Should take. For this reason, since one pulse P of the envelope 19 takes an ideal waveform, as a result, the measurement time Tx coincides with the comparison time Tk. On the other hand, when the electronic key 2 receives a radio wave transmitted due to fraudulent use of the repeater, it can be said that the repeater 16 can relay the radio wave how much, but it is not possible to accurately match the pulse P until the rise and fall. Is possible. Therefore, at this time, as shown in FIGS. 5 and 6, the waveform of the pulse P does not take a normal waveform, and as a result, the measurement time Tx does not coincide with the comparison time Tk. Therefore, in this example, whether or not the communication partner is a regular partner is determined by checking whether or not the measurement time Tx matches the comparison time Tk.

  The repeater use fraud prevention device 17 is a device that executes, on the electronic key 2 side, a series of processing (regular communication confirmation processing) for checking whether or not the communication partner is a regular partner. This is because the outbound communication in which the vehicle 1 communicates with the electronic key 2 using the LF band radio wave uses AM modulation, so if the modulation method is AM modulation, what kind of communication content the radio wave takes. This is because, since the rising always takes the same slew rate (slope), it is possible to perform communication partner identification processing by looking at the measurement time Tx. Note that FM modulation (frequency modulation) is used for return path communication in which radio waves are transmitted from the electronic key 2 to the vehicle 1.

  The repeater use fraud prevention apparatus 17 of this example is explained in full detail below. First, as shown in FIG. 3, the communication control unit 13 of the electronic key 2 is provided with a CPU 21 that comprehensively manages the operation of the electronic key 2. The CPU 21 is connected to a ROM (Read Only Memory: not shown) and a RAM (Random Access Memory: not shown), and executes various operations using the RAM as a work area based on a control program stored in the ROM.

  The LF receiver 14 is formed so as to be capable of receiving radio waves from the three axes of the X axis, the Y axis, and the Z axis. In this case, the LF receiver 14 includes an X-axis receiving antenna 22a that receives radio waves in the X-axis direction, a Y-axis receiving antenna 22b that receives radio waves in the Y-axis direction, and a Z-axis that receives radio waves in the Z-axis direction. A receiving antenna 22c is provided. Each of these receiving antennas 22a to 22c is connected to an AD converter 23 that converts and outputs radio waves received by the receiving antennas 22a to 22c from analog waveforms to digital waveforms. The AD converter 23 converts the received radio wave 24 received by the antennas 22 a to 22 c into a received digital signal 25 having a waveform conforming to the envelope 19 and outputs the received digital signal 25 to the communication control unit 13.

  The communication control unit 13 of the electronic key 2 is provided with a plurality of determination circuits 26 that calculate the measurement time Tx described above and determine whether the measurement time Tx is correct in the process of sending the received digital signal 25 to the CPU 21. It has been. The determination circuit 26 is provided in each of the three reception antennas 22a to 22c and is connected to the corresponding AD converter 23, respectively. The determination circuit 26 receives the received digital signal 25 from the AD converter 23 and executes regular communication confirmation processing based on the received digital signal 25.

  The determination circuit 26 is provided with a time measurement unit 27 that calculates the measurement time Tx. When the time measurement unit 27 receives radio waves by the receiving antennas 22a to 22c, that is, when the input of the H level pulse P from the AD converter 23 is started, the time measurement unit 27 starts the time measurement by starting the counter. The time until the maximum reception value Vmax is obtained is measured. Whether or not the pulse P of the reception digital signal 25 has reached the maximum reception value Vmax is determined by, for example, checking whether or not the reception intensity (reception level) continues for a certain time. Then, the time measuring unit 27 stops the counter when the pulse P of the reception digital signal 25 takes the reception maximum value Vmax, and calculates the time until that time as the measurement time Tx. The time measuring unit 27 corresponds to a measuring unit, and the reception maximum value Vmax corresponds to a reference value.

  The determination circuit 26 includes a determination processing unit 28 that determines whether the smart communication is regular communication by comparing the measurement time Tx with the comparison time Tk. The determination processing unit 28 determines whether the smart communication is regular communication by checking whether the measurement time Tx calculated by the time measurement unit 27 matches the comparison time Tk that the time measurement unit 27 has in advance. The determination processing unit 28 outputs the determination result Sr to the CPU 21. At this time, if the determination processing unit 28 recognizes that the smart communication is regular communication, it outputs a communication permission notification to the CPU 21 as the determination result Sr. If it determines that the smart communication is not regular communication, the communication is not permitted as the determination result Sr. The notification is output to the CPU 21. The determination processing unit 28 corresponds to a determination unit.

  The determination circuit 26 performs normal communication confirmation processing with the received digital signal 25 and then outputs the received digital signal 25 to the CPU 21 via the signal selector 29. The CPU 21 interprets the signal content by reading the combination of “0” and “1” of the received digital signal 25 and executes an operation based on the signal content. When the received signal is received from the determination circuits 26, 26..., The signal selector 29 selects the received digital signal 25 acquired earliest so that the CPU 21 can be operated with the earliest signal received from these signals. The data is output to the CPU 21 as a whole.

  The CPU 21 is provided with a forced termination unit 30 that forcibly terminates smart communication when the smart communication is not regular communication based on the determination result Sr of the determination circuit 26. The forced termination unit 30 determines whether or not smart communication can be performed based on the determination result Sr acquired from the determination circuit 26. If the determination result Sr is a communication permission notification, the smart communication is continued as it is, while the determination result Sr. If is a communication non-permission notification, smart communication is forcibly terminated at that time. Note that the forced termination unit 30 corresponds to a termination unit.

  The electronic key 2 is provided with a notification unit 31 that operates when smart communication is forcibly terminated due to detection of an illegal act of using a repeater. The alerting | reporting part 31 consists of an indicator, a buzzer, etc., for example. Further, the CPU 21 is provided with a notification control unit 32 that manages the lighting operation of the notification unit 31. When the forcible termination unit 30 confirms that the smart communication has been forcibly terminated, the notification control unit 32 operates the notification unit 31 to notify the user of the occurrence of illegal use of the repeater.

Next, the operation of the repeater use fraud prevention apparatus 17 of this example will be described with reference to FIGS.
During smart communication, when the time measuring unit 27 confirms that the electronic key 2 has received the radio wave from the vehicle 1, the time is started until the pulse P of the received digital signal 25 reaches the maximum reception value Vmax. Then, counting of the measurement time Tx is started. At this time, the time measuring unit 27 starts time measurement triggered by the detection of the rising waveform of the pulse P from the AD converter 23. The time measuring unit 27 stops the counter when the received intensity of the received digital signal 25 (received radio wave 24) takes the received maximum value Vmax, and outputs the calculated counter value to the determination processing unit 28 as the measured time Tx.

  When the determination processing unit 28 obtains the measurement time Tx from the time measurement unit 27, the determination processing unit 28 compares the measurement time Tx with a comparison time Tk that is previously stored as an ideal value to determine whether the smart communication is regular communication. To do. At this time, if all three determination circuits 26 obtain a result in which the measurement time Tx and the comparison time Tk match, a communication permission notification is output to the CPU 21 as the determination result Sr. On the other hand, when it is confirmed that at least one of the three determination circuits 26 does not match the measurement time Tx with the comparison time Tk, a communication non-permission notification is output to the CPU 21 as the determination result Sr.

  Here, if the electronic key 2 is located in the outside communication area and the smart communication is properly executed, the electronic key 2 takes the correct slew rate (tilt) as shown in FIG. Receive the rising radio wave. As a result, the measurement time Tx and the comparison time Tk coincide with each other, and the determination circuit 26 outputs a communication permission notification to the forcible termination unit 30 as the determination result Sr. When the forced termination unit 30 receives the communication permission notification from the determination circuit 26, the forcible termination unit 30 recognizes that the ongoing smart communication may be continued, and continues the smart communication as it is.

  On the other hand, when the electronic key 2 receives a radio wave from the vehicle 1 due to a fraudulent act of using a repeater, the electronic key 2 may receive a wave rise as shown in FIG. 5 or FIG. Or it receives a delayed radio wave. Therefore, as a result, the measurement time Tx and the comparison time Tk do not match, and the determination circuit 26 outputs a communication non-permission notification to the forcible termination unit 30 as the determination result Sr. When the forcible termination unit 30 receives the communication non-permission notification from the determination circuit 26, the forcible termination unit 30 recognizes that the ongoing smart communication must be terminated, and forcibly terminates the smart communication. Further, when the notification control unit 32 confirms that the smart communication has been forcibly terminated, the notification control unit 32 operates the notification unit 31 to notify the surroundings and the user of the occurrence of the repeater use fraud.

  As described above, in the case of this example, when the electronic key 2 receives a radio wave, the time until one pulse P of the received digital signal 25 which is the envelope 19 of the received radio wave 24 reaches the reception maximum value Vmax is measured. Whether or not the smart communication is regular communication is determined by checking whether or not the measurement time Tx matches the comparison time Tk. Therefore, it is possible to determine whether the smart communication is regular communication or due to illegal use of the repeater. And when smart communication has the possibility of fraudulent use of the repeater, smart communication is forcibly terminated, so that it is possible to make it difficult for smart communication to be fraudulently established due to fraudulent use of the repeater.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) Calculate a measurement time Tx from when the electronic key 2 receives a radio wave until the amplitude of the received radio wave reaches the maximum reception value Vmax. If the measurement time Tx matches the comparison time Tk, smart communication is performed. If it is processed as regular communication and the measurement time Tx does not coincide with the comparison time Tk, the smart communication is processed as an unauthorized communication, that is, the communication is performed by an illegal act of using the repeater, and the smart communication is forcibly terminated. For this reason, since it is possible to forcibly terminate smart communication when it is considered that the communication is due to fraudulent use of the repeater, it is difficult to establish unauthorized communication due to fraudulent use of the repeater.

  (2) A series of processing for checking whether smart communication is regular communication is executed on the outgoing communication side that performs communication by amplitude modulation among the mutual communication of smart verification. By the way, the radio wave conforming to the amplitude modulation is the radio wave when the binary data is switched from “0” to “1” as shown in FIGS. The waveform takes the same rise. For this reason, if a series of processes for checking whether smart communication is regular communication is performed on the outbound communication side that performs communication by amplitude modulation, the measurement time Tx can be accurately measured even when the signal content of radio waves is different. As a result, the communication determination of this example can be executed more accurately.

  (3) A series of processing for checking whether smart communication is regular communication is executed on the electronic key 2 side. For this reason, in the case of smart communication as in this example, if communication is executed by unauthorized use of a repeater, smart communication is forcibly terminated when the electronic key 2 receives the request signal Srq from the vehicle 1. Smart communication can be forcibly terminated at an early stage of communication loopback.

  (4) The time from when the electronic key 2 starts reception until the amplitude of the received radio wave takes the maximum reception value Vmax is calculated as the measurement time Tx. Therefore, even if the reception intensity of radio waves changes, the measurement time Tx can be set to the same value both when the reception intensity is high and when the reception intensity is low. Therefore, the correct measurement time Tx can be calculated even if the radio wave reception intensity changes.

  (5) When the measurement time Tx does not coincide with the comparison time Tk, that is, when it is determined that the smart communication is due to unauthorized use of the repeater, the notification unit 31 notifies the surroundings and the user. Therefore, it is possible to notify the vehicle theft to the surroundings, and further, it is a threat to the theft, so that the crime prevention property against theft can be further enhanced.

Note that the embodiment is not limited to the configuration described so far, and may be modified as follows.
The repeater use fraud prevention device 17 is not limited to being executed on the electronic key 2 side. In other words, the repeater use fraud prevention device 17 may be provided in the vehicle 1 so that the regular communication confirmation process is executed on the vehicle 1 side. That is, by checking the waveform of the radio wave received from the electronic key 2, it may be determined whether the smart communication is regular communication.

The regular communication confirmation process is not limited to being performed under AM modulation, and may be performed under FM modulation.
The reference value is not limited to the maximum reception value Vmax, and may be a predetermined reception intensity set as a fixed value as shown in FIG.

  The measurement time Tx is not limited to the time width required for receiving the H level 1 pulse P until it takes the maximum reception value Vmax. For example, as shown in FIG. 9, the time required from the point 51 where the reception level is stable after the start of reception of one pulse P to the predetermined reception intensity Vz may be used. That is, the determination may be performed by obtaining a slew rate per unit time and checking whether the slew rate takes a reference value.

  ・ Regular communication confirmation processing, that is, determination for calculating the measurement time Tx and comparing it with the comparison time Tk is not limited to that performed by looking at the rising waveform of the received radio wave; But you can.

The one pulse seen when calculating the measurement time Tx is not limited to the first pulse P of the received radio wave, and may be the second or later.
・ Smart communication is not limited to being forcibly terminated when fraudulent use is detected. For example, although the smart communication itself is continued, use of the in-vehicle device may not be permitted as a result.

When smart communication is determined at the slew rate, the normal determination of smart communication may be performed by looking at the reception level of the envelope 19 at that time in addition to the slew rate.
-The alerting | reporting part 31 is not limited to an indicator and a buzzer, For example, when a display is mounted in the electronic key 2, you may display a message on this display.

  -Notification of occurrence of fraudulent use of the repeater is not limited to being executed on the electronic key 2 side. For example, when the electronic key 2 detects the occurrence of fraudulent use of the repeater, the fact may be notified to the vehicle 1 by radio and the notification may be executed by the vehicle 1.

  -Notification of occurrence of fraudulent use of the repeater is not limited to the electronic key 2 or the vehicle 1. For example, the user's mobile phone may be notified by e-mail using a network such as the Internet.

The electronic key 2 is not limited to the three-axis correspondence, and may be a key that can receive radio waves only in one axis direction.
The antenna of the electronic key 2 is not limited to being provided separately for reception and transmission, and may be a transmission / reception shared antenna.

  The key operation free system 3 is not limited to the radio wave frequency being different between the forward path and the return path of mutual communication, and may be the same frequency. Further, the frequency used for communication is not limited to LF or UHF, and other bands can be used.

-An electronic key system is not limited to the key operation free system 3, For example, it is good also as an immobilizer system which performs ID collation with the transponder incorporated in the electronic key 2. FIG.
The repeater use fraud prevention device 17 is not limited to being mounted on the vehicle 1 and may be used for other devices and devices such as a house.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle as key communication object, 2 ... Electronic key, 3 ... Key operation free system as electronic key system, 17 ... Repeater use fraud prevention apparatus, 19 ... Envelope, 27 ... Time measuring part as measuring means , 28 ... determination processing unit as determination unit, 30 ... forced termination unit as termination unit, 31 ... notification unit constituting notification unit, 32 ... notification control unit constituting notification unit, P ... pulse, Vmax ... reference value Reception maximum value, Tx: measurement time, Tk: comparison time.

Claims (5)

An ID reply request is transmitted from the key communication target, ID verification is performed using the ID code returned by the electronic key in response to the request, and the electronic key and the key communication target perform mutual communication in accordance with the ID verification. When executing, the radio wave is modulated and transmitted from one to the other. When the other receives the radio wave, the radio wave is acquired by envelope detection, and the signal content of the radio wave is acquired from the signal waveform of the envelope. In the electronic key system repeater use fraud prevention device,
Measuring means for measuring the time required for the amplitude of one pulse of the received envelope to take a reference value;
A determination means for determining whether or not the measurement time of the measurement means coincides with a comparison time taken in communication according to regular communication;
An apparatus for preventing fraudulent use of a repeater in an electronic key system, comprising: ending means for forcibly ending or restricting communication of the ID collation when the measurement time takes a value different from the comparison time. In the mutual communication, at least one of the forward communication and the backward communication is executed by amplitude modulation, and the measurement means, the determination means, and the end means are the electric wave reception side of the amplitude modulation among the electronic key and the key communication target. The repeater use fraud prevention apparatus of the electronic key system according to claim 1, wherein the apparatus is used in the electronic key system. The repeater use fraud prevention apparatus for an electronic key system according to claim 1 or 2, wherein the measuring means, the determining means, and the ending means are provided in the electronic key. The relay of the electronic key system according to any one of claims 1 to 3, wherein the reference value is a maximum reception value that can be taken at a maximum when the one pulse of the envelope is received. Device use fraud prevention device. 5. The electronic key system repeater use according to claim 1, further comprising a notifying unit that notifies that when the measurement time takes a value different from the comparison time. 6. Fraud prevention device.

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