JP2016038332A - Distance measurement system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance measurement system that allows a distance measurement to be implemented at timing along an intension of a user.SOLUTION: Both of a vehicle 1 and an electronic key 2 are configured to mutually transmit a UWB radio wave Suwb at a random pattern when executing distance collation, and in both of the vehicle 1 and the electronic key 2, timing information when transmitting/receiving the UWB radio wave Suwb, that is, transmission timing information and reception timing information are respectively measured. The electronic key 2 is configured to transmit the acquired transmission/reception timing information to the vehicle 1, and the vehicle 1 is configured to obtain a propagation time of the UWB radio wave Suwb for each set of transmitted/received UWB radio waves Suwb on the basis of the transmission/reception timing information owned by the vehicle 1 and the transmission/reception timing information acquired from the electronic key 2; and measure a distance between the vehicle 1 and the electronic key 2 on the basis of the obtained propagation time.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a distance measuring system that measures a distance between a communication master and a communication terminal.

  Conventionally, in Patent Document 1, when a radio wave transmitted from one terminal is received on the other side, a response is returned from the other side to the other after a lapse of a certain time, and between the two terminals based on the time required from transmission to response reception A technique for measuring distance is disclosed.

Special table 2009-505060

In this type of distance measurement system, there is a need to execute it accurately at the timing when the user wants to perform distance measurement.
The objective of this invention is providing the distance measurement system which can be set as the distance measurement implemented at the timing according to a user's intention.

  The distance measurement system that solves the above problem is configured to measure the distance between the communication master and the communication terminal, by randomly transmitting UWB radio waves from both the communication master and the communication terminal toward the other party. A communication processing unit that transmits and receives the UWB radio wave; a timing information measurement unit that measures timing information when the UWB radio wave is transmitted and received in each of the communication master and the communication terminal; and the timing information is transmitted to the communication master and the communication terminal. Based on the timing information collected in one of the communication master and the communication terminal, the UWB radio wave is transmitted to the communication master and the communication terminal based on the timing information collected in one of the communication master and the communication terminal by transmitting from one to the other Calculate the propagation time required to send to both parties, and between the two based on the propagation time Distance and a distance measuring section for measuring.

  According to this configuration, the UWB radio waves are sent from both the communication master and the communication terminal in a random pattern, and the timing information when the UWB radio waves are transmitted and received by both the communication master and the communication terminal is measured and communicated. Collect in one of the master and communication terminals. One of the communication master and the communication terminal measures the distance between the two parties for each set of transmitted / received UWB radio waves based on the collected timing information. At this time, if all or some of the distances of the respective sets match, the measurement result is validated. In this way, when measuring the distance between the two parties, UWB radio waves are transmitted at different timings each time. For example, even if a malicious third party copies and transmits UWB radio waves, transmission / reception of UWB radio waves is not possible. The timing of will not match the regular. At this time, the distances of the respective groups do not coincide with each other, so that the distance measurement in this case can be invalidated. Therefore, it becomes possible to set it as the distance measurement implemented at the timing according to a user's intention.

  In the distance measurement system, it is preferable that the information collecting unit transmits the timing information acquired in one of the communication master and the communication terminal to the other by encrypted communication. According to this configuration, it is possible to ensure security when transmitting timing information to the other party.

  The distance measurement system includes a pre-authentication unit that confirms the pair validity of the communication master and the communication terminal by wireless communication before sending the UWB radio wave, and the communication processing unit is authenticated by the pre-authentication unit. It is preferable that the transmission of the UWB radio wave is started on the condition that it is established. According to this configuration, since the distance measurement is performed after first confirming the pair validity of the communication master and the communication terminal, it is advantageous in preventing the other party from being mistaken in the distance measurement.

  In the distance measurement system, it is preferable that the timing information measuring unit measures the timing information using only the first received pulse when receiving the UWB radio wave. According to this configuration, if a plurality of pulses are received by multipath, the received radio wave becomes a lump of waves, but the distance measurement is performed with only the first pulse, so the distance measurement is more accurate. It is advantageous to do.

  In the distance measurement system, the filter unit capable of removing noise from the UWB radio wave and the frequency of the local oscillator of the filter unit are switched, and the band of the filter unit is switched to receive the signal while optimizing the filter unit. And a filter control unit that removes noise from the UWB radio wave, and the distance measuring unit preferably measures a distance between the communication master and the communication terminal based on the UWB radio wave after noise removal. According to this configuration, by switching the frequency of the local oscillator of the filter unit, a band in which the filter unit works is searched, and the filter unit is optimized. As a result, even if noise is generated in the communication environment of UWB radio waves, it is possible to eliminate the noise by matching the band of the filter unit to the band suitable for the noise. Is advantageous. Further, since the filter unit is variable, it is possible to cope with noise of a plurality of frequencies.

  In the distance measurement system, it is preferable that the filter unit is a band rejection filter. According to this configuration, the band rejection filter can target noise at a certain frequency and accurately remove it.

  In the distance measurement system, the band setting of the filter unit is such that the UWB radio wave is transmitted a plurality of times in one transmission from one of the communication master and the communication terminal, and at least one of the UWB radio waves is normally received by the other If it is possible to determine whether or not the UWB radio wave can be normally received on the other side, the current value of the local oscillator is maintained and the band of the filter unit is determined. After waiting for the switching of the frequency, the UWB radio wave is transmitted a plurality of times again to confirm whether or not the UWB radio wave can be received again, and the above series of operations is repeated until the UWB radio wave can be normally received. Therefore, it is preferable that the filter unit is optimized. According to this configuration, when the UWB radio wave is transmitted when setting the band of the filter unit, it is transmitted a plurality of times, which is advantageous in ensuring the reliability of the determination. In addition, when re-executing transmission of UWB radio waves a plurality of times, it waits for frequency switching of the local oscillator, which is advantageous for ensuring that the other party receives UWB radio waves.

  In the distance measurement system, it is preferable that the band setting of the filter unit is executed by both the communication master and the communication terminal. According to this configuration, it is possible to optimize the filter units of both the communication master and the communication terminal, which is further advantageous in ensuring communication establishment.

  A distance measuring system that solves the above problems includes a filter unit capable of removing noise from UWB radio waves communicated from one of the communication master and the communication terminal to the other in a configuration for measuring the distance between the communication master and the communication terminal. A filter control unit that removes noise from the received UWB radio wave while optimizing the filter unit by switching a frequency of the local oscillator of the filter unit and switching a band of the filter unit; and A distance measuring unit that measures a distance between the communication master and the communication terminal based on the UWB radio wave.

  According to this configuration, by switching the frequency of the local oscillator of the filter unit, a band in which the filter unit works is searched, and the filter unit is optimized. Therefore, even if noise is generated in the communication environment of UWB radio waves, the band of the filter unit is adjusted to a band adapted to the noise to remove the noise. For this reason, when the user wants to execute communication between the communication master and the communication terminal, even if noise is present in the communication environment of UWB radio waves, it is possible to establish communication without being affected by this. Therefore, it becomes possible to set it as the distance measurement implemented at the timing according to a user's intention.

  According to the present invention, distance measurement can be performed at a timing according to the user's intention.

The lineblock diagram of the distance measuring system of a 1st embodiment. The circuit diagram of a UWB radio wave transmission / reception circuit. The communication timing chart which shows the general concept of distance measurement. The transmission outline figure of UWB electric wave. The communication timing chart which shows the outline | summary of the distance measurement of this example. It is a timing chart of the communication of the UWB electric wave sent in a certain group, (a) is a figure of the communication pattern which transmits a UWB electric wave to a vehicle after receiving UWB electric wave with an electronic key, (b) is an electronic key in vehicles. The figure of the communication pattern which transmits a UWB electric wave to a vehicle before receiving a UWB electric wave from. FIG. It is a figure used by description of 2nd Embodiment, (a) is a frequency spectrum figure of a UWB radio wave, (b) is a radio wave waveform figure of the UWB radio wave on which noise got. The circuit diagram of the UWB electromagnetic wave transmission / reception circuit provided with the filter part. (A), (b) is a frequency spectrum figure which shows the change of the zone | band of a filter part accompanying the switching of the frequency of a local oscillator. (A), (b) is a frequency spectrum figure which shows the change of the zone | band of a filter part accompanying the switching of the frequency of a local oscillator. The timing chart which shows the flow of communication when the zone | band of a filter part is set. The flowchart performed at the time of noise removal operation | movement.

(First embodiment)
Hereinafter, a first embodiment of a distance measuring system will be described with reference to FIGS.
As shown in FIG. 1, the vehicle 1 includes an electronic key system 3 that performs ID verification wirelessly with the electronic key 2. The electronic key system 3 is a key operation-free system that executes ID collation by narrowband wireless (communication distance: 1 to several meters) triggered by communication from the vehicle 1. Hereinafter, the ID verification of the key operation free system is referred to as “smart verification”, and the communication is referred to as “smart communication”.

  The vehicle 1 includes a verification ECU (Electronic Control Unit) 4 that confirms the validity of the electronic key 2 in ID verification, a body ECU 5 that manages the power supply of the on-vehicle electrical components, and an engine ECU 6 that controls the engine 7. These ECUs are connected through a communication line 8 in the vehicle. The communication line 8 is a CAN (Controller Area Network) or a LIN (Local Interconnect Network). The electronic key ID is written and stored in the memory 9 of the verification ECU 4 as the ID of the electronic key 2 registered in the vehicle 1.

  The vehicle 1 includes an in-vehicle transmitter 10 capable of transmitting ID verification radio waves outside the vehicle, an in-vehicle transmitter 11 capable of transmitting ID verification radio waves into the vehicle, and a vehicle receiver 12 capable of receiving radio waves from the electronic key 2. With. The external transmitter 10, the in-vehicle transmitter 11, and the vehicle receiver 12 are connected to the verification ECU 4 and their operations are managed. The vehicle-mounted transmitter 10 and the vehicle-mounted transmitter 11 can transmit LF (Low Frequency) band radio waves. The vehicle receiver 12 can receive radio waves in the UHF (Ultra High Frequency) band. The body ECU 5 controls the operation of the door lock mechanism 13, which is a mechanical part that switches between locking and unlocking the vehicle door.

  The vehicle 1 includes an engine switch 14 that is operated when the vehicle power source is switched. The engine switch 14 is a push-type momentary switch. The verification ECU 4 determines the power supply state based on the detection signal input from the engine switch 14 and switches the vehicle power supply to take that state. The power state includes IG off, ACC on, IG on, and engine start.

  The electronic key 2 includes a key control unit 15 that controls the operation of the electronic key 2, a reception unit 16 that can receive radio waves transmitted from the vehicle 1, and a transmission unit 17 that can transmit radio waves to the vehicle 1. An electronic key ID used for ID verification with the vehicle 1 is written and stored in the memory 18 of the key control unit 15. The receiving unit 16 can receive LF radio waves. The transmission unit 17 can transmit UHF radio waves.

  When the outside transmitter 10 forms a communication area for LF radio waves outside the vehicle, when the electronic key 2 enters this communication area, a smart check outside the vehicle is executed. The smart verification outside the vehicle includes vehicle code verification for authenticating a unique vehicle code of the vehicle 1, challenge response authentication using an encryption key, and electronic key ID verification for authenticating an electronic key ID. The verification ECU 4 confirms whether or not all of these verifications are established in the electronic key 2 located outside the vehicle at the time of smart verification outside the vehicle. On the other hand, when the electronic key 2 enters the communication area of the in-vehicle transmitter 11, the verification ECU 4 starts the in-vehicle smart verification and executes various verifications similar to the external smart verification.

  The electronic key system 3 includes a distance measurement system 21 that measures a distance d between the communication master 19 (an example is a verification ECU 4) and a communication terminal 20 (an example is an electronic key 2). The premise of the operation of the distance measurement system 21 of this example is that both the communication master 19 and the communication terminal 20 send UWB (Ultra Wide Band) radio waves Suwb with a random transmission pattern. The distance measurement system 21 measures the distance d between the two persons in the communication process of the ID verification of the electronic key system 3. The electronic key system 3 determines whether or not the distance d is within a specified value in the above-described various verifications (vehicle code verification, challenge response authentication, electronic key ID verification) in smart verification (smart verification outside the vehicle, smart verification inside the vehicle). If it is confirmed that the distance collation to be established is established, the smart collation is processed as established.

  As shown in FIG. 2, the distance measurement system 21 includes a UWB radio wave transmission / reception circuit 22 that receives a UWB radio wave Suwb. The UWB radio wave transmission / reception circuit 22 is provided in each of the vehicle 1 and the electronic key 2, and the vehicle 1 has 22a and the electronic key 2 has 22b. The UWB radio wave transmission / reception circuit 22a includes a UWB radio wave Suwb transmission function (transmission circuit) and a UWB radio wave Suwb reception function (reception circuit).

  Specifically, the UWB radio wave transmission / reception circuit 22a includes a communication antenna 23a shared for transmission / reception of the UWB radio wave Suwb, a circulator 49a that selectively distributes signals, and a band-pass filter that allows only radio waves of a predetermined frequency to pass through in the received signal. 24a, a first amplifier 25a that amplifies the signal that has passed through the filter, a second amplifier 26a that adjusts the gain of the signal that has passed through the first amplifier 25a, and a signal that has passed through the second amplifier 26a (envelope detection) ) And a comparator 28a that binarizes the detected signal with “0” or “1”. The UWB radio wave transmission / reception circuit 22a includes a pulse oscillation circuit 34a that generates a single pulse of the UWB radio wave Suwb to be transmitted, and a third amplifier 39a that amplifies the UWB radio wave Suwb to be transmitted. When transmitting the UWB radio wave Suwb, the circulator 49a causes the signal input from the pulse oscillation circuit 34a through the third amplifier 39a to be transmitted from the communication antenna 23a as the UWB radio wave Suwb. When the circulator 49a receives the UWB radio wave Suwb with the communication antenna 23a, the circulator 49a sends the received radio wave to the bandpass filter 24a. The first amplifier 25a may be an LNA (Low Noise Amplifier). The second amplifier 26a may be AGC (Automatic Gain Control). When the UWB radio wave transmission / reception circuit 22a receives the UWB radio wave Suwb, the UWB radio wave transmission / reception circuit 22a outputs a binarized signal (single pulse signal) after comparing the UWB radio wave Suwb to the verification ECU 4. Further, the UWB radio wave transmission / reception circuit 22a operates so as to transmit the UWB radio wave Suwb from the communication antenna 23a at a certain timing when the distance matching is performed.

  Similarly to the UWB radio wave transmission / reception circuit 22a, the UWB radio wave transmission / reception circuit 22b also includes a communication antenna 23b, a band pass filter 24b, a first amplifier 25b, a second amplifier 26b, a detection circuit 27b, a comparator 28b, a circulator 49b, a pulse oscillation circuit 34b, and the like. A third amplifier 39b is provided. The UWB radio wave transmission / reception circuit 22b can transmit the UWB radio wave Suwb at a certain timing when the distance matching is performed, and at the time of receiving the UWB radio wave Suwb transmitted from the vehicle 1, the binary value after comparing the UWB radio wave Suwb. The control signal (single pulse signal) is output to the key control unit 15.

  Returning to FIG. 1, the distance measurement system 21 includes a communication processing unit 29 that transmits and receives the UWB radio wave Suwb in both the communication master 19 and the communication terminal 20. The communication processing unit 29 includes a communication processing unit 29 a provided in the communication master 19 and a communication processing unit 29 b provided in the communication terminal 20. The communication processing unit 29 transmits and receives the UWB radio wave Suwb at random by transmitting the UWB radio wave Suwb from both the communication master 19 and the communication terminal 20 to the other party through the transmission function of the UWB radio wave transmission / reception circuits 22a and 22b. Let The UWB radio wave Suwb is an ultra-wideband radio wave and is a signal having an extremely short pulse (see FIG. 4 and the like).

  The distance measurement system 21 includes a timing information measuring unit 30 that measures timing information Dti when each of the communication master 19 and the communication terminal 20 transmits and receives the UWB radio wave Suwb in each of the communication master 19 and the communication terminal 20. The timing information measurement unit 30 includes a timing information measurement unit 30 a provided in the communication master 19 and a timing information measurement unit 30 b provided in the communication terminal 20. The timing information Dti includes transmission timing information Dti-A that is the time (time) at which the UWB radio wave Suwb is transmitted, and reception timing information Dti-B that is the time (time) at which the UWB radio wave Suwb is received from the other party. It is.

  The distance measurement system 21 includes an information collection unit 31 that collects timing information Dti on one of the communication master 19 and the communication terminal 20. The information collection unit 31 includes an information notification unit 31a on the side that sends the timing information Dti to the other party, and an information acquisition unit 31b on the side that receives the timing information Dti sent by the information notification unit 31a. When the distance d is measured by the communication master 19, the information notification unit 31 a is provided in the communication terminal 20, and the information acquisition unit 31 b is provided in the communication master 19. The information notification unit 31a may transmit the timing information Dti to the vehicle 1 by encrypted communication. For encryption communication, an encryption key used for challenge response authentication may be used.

  The distance measurement system 21 includes a distance measurement unit 32 that measures a distance d between two persons based on timing information Dti collected on one of the communication master 19 and the communication terminal 20. The distance measuring unit 32 is provided in the communication master 19. The distance measurement unit 32 uses the timing information Dti (transmission timing information Dti-A and reception timing information Dti-B) collected in one of the communication master 19 and the communication terminal 20 to transmit the UWB radio wave Suwb to the communication master 19 and the communication terminal. The propagation time 2Δt required to send to both of 20 is calculated, and the distance d between the two is measured based on this propagation time 2Δt.

  The distance measurement system 21 includes a pre-authentication unit 33 that confirms the pair validity of the communication master 19 and the communication terminal 20 by wireless communication before sending UWB radio waves Suwb. The pre-authentication unit 33 confirms the validity of the electronic key 2 that is currently in communication with the vehicle 1 by, for example, confirming whether smart verification is established. The communication processing unit 29 starts sending UWB radio waves Suwb on the condition that the authentication of the pre-authentication unit 33 is established.

Next, the operation of the distance measurement system 21 will be described with reference to FIGS.
As shown in FIG. 3, for example, when the terminal 36 receives a radio wave transmitted from the terminal 35 at time “tA”, a response is returned from the terminal 36 to the terminal 35 after a predetermined time “tb” has elapsed. It is well known how to calculate the distance d between the two persons by calculating the time required for two-way communication between the terminal 35 and the terminal 36. This is one of the countermeasures against the smart verification being illegally established using the repeater when the electronic key 2 is located far away from the vehicle 1. When the value is larger than the specified value, this illegal communication can be dealt with if smart verification is not established.

  When measuring the distance d between the terminals 35-36, if the position has not changed, the time required for the outbound communication until the radio wave transmitted from the terminal 35 is received by the terminal 36 and vice versa The time required is the same “ta”. Further, when the time required for the response operation at the terminal 36 is “tb” and the propagation speed of the radio wave is the speed of light c, the distance d between the terminals 35-36 is “2d = c × 2ta”, that is, It can be calculated from “2d = c × ((tB−tA) −tb)”. However, this calculation method measures the time of the radio wave propagating at the speed of light, and it is necessary to accurately manage the time “tb” required for the response operation of the terminal 36. Although it is conceivable to set “tb” to a constant value, in this case, the start of the forward communication, that is, the electronic key 2 waits for a predetermined time, and the communication time becomes long.

  As shown in FIG. 4, the UWB radio wave Suwb has a waveform with an extremely short pulse length (for example, about 1 ns). For this reason, there is an advantage that it is easy to determine at which timing radio waves can be transmitted and received. However, as a contradiction, if only a single pulse such as UWB radio wave Suwb is sent, a malicious third party can easily copy and send the single pulse, leading to unauthorized establishment of communication. there is a possibility. In this case, an ID including a rolling code or the like may be transmitted instead of a single pulse. However, ID verification is imposed on communication, processing becomes complicated, and communication time becomes long.

  FIG. 5 illustrates an operation procedure of the distance measurement system 21 of this example. The pre-authentication unit 33 intermittently LF-transmits a wake signal Swk for activating the electronic key 2 from the external transmitter 10 (in-vehicle transmitter 11), for example, by executing smart communication at regular or irregular timing. To do. When the electronic key 2 receives the wake signal Swk, the electronic key 2 starts from a standby state and transmits the ACK signal Sack to the vehicle 1 by UHF. The pre-authentication unit 33 determines that the smart communication is established if the ACK signal Sack can be received within a predetermined time after transmitting the wake signal Swk, and performs various verifications such as vehicle code verification, challenge response authentication, and electronic key ID verification. Is executed with the electronic key 2. When the vehicle 1 starts to establish these ID verifications, the vehicle 1 shifts to distance verification.

  The ID collation imposed here is not limited to vehicle code collation, challenge response authentication, and electronic key ID collation, and only one of these collations may be imposed. Further, the ID verification imposed here is not limited to these verifications, and the authentication may be any authentication that can confirm pairing between the vehicle 1 and the electronic key 2. In addition, it is necessary to confirm the pairing (electronic key ID) of the vehicle 1 and the electronic key 2 in the process of the distance verification if the verification between the two parties is not performed before starting the distance verification. is there.

  When the pairing can be confirmed by various verifications between the vehicle 1 and the electronic key 2, the timing information measuring unit 30 a of the vehicle 1 presses the time stamp on the timer 37 of the vehicle 1, for example, and starts the vehicle from this point of time. The time measurement at 1 is started. On the other hand, if the timing information measuring unit 30b of the electronic key 2 can acquire the notification that the pairing of the vehicle 1 and the electronic key 2 has been confirmed from the vehicle 1 by communication, for example, a time stamp is pressed on the timer 38 of the electronic key 2 or the like. Then, time measurement using the electronic key 2 is started from this point.

  By the way, it is desirable that the time stamps of the timers 37 and 38 are exactly the same time, but it is difficult to make them coincide completely. Therefore, in reality, the time stamp of the timer 38 may be shifted from the timer 37 by “ε1”. However, since this time shift “ε1” is canceled in the process of distance calculation described later, even if a time shift occurs, it can be ignored.

  At the start of distance verification, the vehicle 1 and the electronic key 2 transmit UWB radio waves Suwb at random timings. Specifically, the communication processing unit 29a of the vehicle 1 transmits the UWB radio wave Suwb from the UWB radio wave transmission / reception circuit 22a (communication antenna 23a) at the transmission timings “t1”, “t5”, and “t10”. Send to. At this time, the timing information measuring unit 30a of the vehicle 1 measures the transmission timings “t1”, “t5”, “t10” of the UWB radio wave Suwb based on the time measured by the timer 37, and this is measured as “transmission on the vehicle 1 side”. Acquired as “timing information Dti-A”.

  On the other hand, the communication processing unit 29b of the electronic key 2 transmits the UWB radio wave Suwb from the UWB radio wave transmission / reception circuit 22b (communication antenna 23b) to the vehicle 1 at the transmission timings “t2”, “t7”, and “t9”. At this time, the timing information measuring unit 30b of the electronic key 2 measures the transmission timings “t2”, “t7”, “t9” of the UWB radio wave Suwb based on the time measured by the timer 38, Transmission timing information Dti-A ”. In transmitting the UWB radio wave Suwb in the vehicle 1 and the electronic key 2, it is not necessary to synchronize both transmission timings.

  Thus, in this example, “t1” and “t2” are independent timings, and thus have arbitrary values. The vehicle 1 side transmits the next UWB radio wave Suwb after elapse of “t5-t1” from “t1” which is the first transmission time of the UWB radio wave Suwb, and the next UWB radio wave after elapse of “t10-t5”. Take action to send Suwb. On the other hand, the electronic key 2 side transmits the next UWB radio wave Suwb after elapse of “t7-t2” from “t2”, which is the first transmission time of the UWB radio wave Suwb, and continues after the elapse of “t9-t7”. The UWB radio wave Suwb is transmitted. Thus, when transmitting the UWB radio wave Suwb from the vehicle 1 and the electronic key 2, only the radio wave transmission interval needs to be controlled in the vehicle 1 and the electronic key 2.

  The electronic key 2 transmits the UWB radio wave Suwb transmitted from the vehicle 1 at timings “t1”, “t5”, and “t10”, respectively, to the UWB radio wave transmission / reception circuit 22b at timings “t3”, “t6”, and “t12”. Received by (communication antenna 23b). The received radio wave is passed through the UWB radio wave transmission / reception circuit 22b and converted into a single pulse signal, and the key control unit 15 decodes the data. The timing information measuring unit 30b of the electronic key 2 uses the timer 38 to measure the reception timings “t3”, “t6”, “t12” of the UWB radio wave Suwb received from the vehicle 1, Obtained as “reception timing information Dti-B”.

  The vehicle 1 transmits the UWB radio wave Suwb transmitted from the electronic key 2 at the timings “t2”, “t7”, and “t9” to the UWB radio wave transmission / reception circuit 22a at the timings “t4”, “t8”, and “t11”, respectively. It is received by (communication antenna 23a). This received radio wave is passed through the UWB radio wave transmission / reception circuit 22a and converted into a single pulse signal, and the verification ECU 4 decodes the data. The timing information measuring unit 30a of the vehicle 1 uses the timer 37 to measure the reception timings “t4”, “t8”, “t11” of the UWB radio wave Suwb received from the electronic key 2, Acquired as “timing information Dti-B”.

  Since the UWB radio wave Suwb propagates at the speed of light, even if the UWB radio wave Suwb is exchanged several to several tens of times, the positional relationship between the vehicle 1 and the electronic key 2 does not change, and the distance d is constant. It can be considered. In addition, it is assumed that the suffix (numerical string) attached next to “t” is assigned a numerical value in the order of time passage.

  When the sending of all UWB radio waves Suwb (three sets in this example) is completed, the information notifying unit 31a of the electronic key 2 performs the timing of the UWB radio wave Suwb acquired by the timing information measuring unit 30b of the electronic key 2. Information Dti (transmission timing information Dti-A and reception timing information Dti-B on the electronic key 2 side) is notified to the vehicle 1. In this example, time information of “t2”, “t3”, “t6”, “t7”, “t9”, “t12” is notified from the electronic key 2 to the vehicle 1 as the timing information Dti. The notification of the timing information Dti may be performed using encrypted communication. The encryption key used for encryption communication may be the key used for challenge response authentication.

  The information acquisition unit 31b of the vehicle 1 includes “t1”, “t4”, which are timing information Dti (transmission timing information Dti-A and reception timing information Dti-B on the vehicle 1 side) of the UWB radio wave Suwb transmitted and received by the vehicle 1. “T5”, “t7”, “t8”, and “t11” are acquired in the vehicle 1 in advance. In addition, the information acquisition unit 31b “t2”, “t3”, “t6” of the timing information Dti transmitted from the electronic key 2 (transmission timing information Dti-A and reception timing information Dti-B on the electronic key 2 side). , “T7”, “t9”, “t12” are acquired in the vehicle 1. In this way, the vehicle 1 obtains all data “t1” to “t12” of the transmission / reception time (transmission / reception timing) of the UWB radio wave Suwb sent between the vehicle 1 and the electronic key 2.

  As shown in FIGS. 6A and 6B, the distance measuring unit 32 determines the vehicle 1 and the electronic key 2 based on “t1” to “t12” that are the timing information Dti collected by the information acquiring unit 31b. Measure the distance d. The communication example shown in FIG. 6A is a pattern in which the electronic key 2 sends back the UWB radio wave Suwb to the vehicle 1 after the electronic key 2 receives the UWB radio wave Suwb transmitted from the vehicle 1. The communication example shown in FIG. 6B is a pattern in which the electronic key 2 transmits the UWB radio wave Suwb to the vehicle 1 before the electronic key 2 receives the UWB radio wave Suwb transmitted from the vehicle 1.

  In the case of FIG. 6A, in the UWB radio wave Suwb sent to the first set, “t2” is the radio wave reception timing of the electronic key 2, and “t3” is the radio wave transmission timing from the electronic key 2. Yes. In this case, the propagation time Δt until the UWB radio wave Suwb randomly transmitted from the vehicle 1 reaches the electronic key 2 is “Δt = t2−t1”. Further, the propagation time Δt until the UWB radio wave Suwb randomly transmitted from the electronic key 2 reaches the vehicle 1 is “Δt = t4−t3”. For this reason, the propagation time “2Δt” of the UWB radio wave Suwb transmitted between the vehicle 1 and the electronic key 2 is calculated by adding “(t2−t3) + (t4) by adding the left side and the right side of the above two formulas. -T1) ".

  In the case of FIG. 6B, in the UWB radio wave Suwb sent to the first set, “t2” is the radio wave transmission timing from the electronic key 2, and “t3” is the radio wave reception timing of the electronic key 2. Yes. In this case, the propagation time Δt until the UWB radio wave Suwb randomly transmitted from the vehicle 1 reaches the electronic key 2 is “Δt = t3−t1”. Further, the propagation time Δt until the UWB radio wave Suwb randomly transmitted from the electronic key 2 reaches the vehicle 1 is “Δt = t4−t2”. For this reason, the propagation time “2Δt” of the UWB radio wave Suwb transmitted between the vehicle 1 and the electronic key 2 is calculated by adding “(t3−t2) + (t4) by adding the left side and the right side of the above two formulas. -T1) ".

  Here, both the expressions “Δt = (t2−t3) + (t4−t1)” and “Δt = (t3−t2) + (t4−t1)” are verified. The previous equation is (t2-t3), while the latter equation is (t3-t2), and it can be seen that the front and rear positions of “t2” and “t3” are interchanged. However, since the relationship in which the transmission timing is subtracted from the reception timing is the same in both the previous equation and the latter equation, the calculation results can be regarded as the same. That is, even if the UWB radio wave Suwb sent by the vehicle 1 and the electronic key 2 intersects, the same calculation result as that obtained when the intersection does not occur can be obtained.

  Considering a case where the timer 38 has a time difference of “ε1”, for example, in the calculation of the example of FIG. 6A, “(t2 + ε1) −t1 = Δt” and “t4− (t3 + ε1) = Δt”. In the process of adding the right and left sides to each other, “ε1” is canceled out. Therefore, even if there is a time difference between the timers 37 and 38, it can be seen that there is no problem in distance calculation.

  The distance measurement unit 32 calculates “2Δt”, which is a propagation time required for transmission / reception of the UWB radio wave Suwb in each pair to which the UWB radio wave Suwb is sent. As an example, the first set of propagation times “2Δt” is obtained from “t1” to “t4”, and the second set of propagation times “2Δt” is obtained from “t5” to “t8”. “2Δt” is obtained from “t9” to “t12”. As described above, three propagation times “2Δt” in this example can be obtained from one set to three sets.

  Note that the pair of UWB radio waves Suwb used for the propagation time 2Δt is not limited to the most recently sent pair, but for example, the UWB radio wave Suwb sent from the first set of vehicles 1 to the electronic key 2 and the second set of electrons. It may be a combination across other sets, such as UWB radio wave Suwb sent from the key 2 to the vehicle 1. That is, in any combination, the same “2Δt” can be calculated as long as the UWB radio wave Suwb of the vehicle 1 → electronic key 2 and the UWB radio wave Suwb of the electronic key 2 → vehicle 1 are combined.

  The distance measuring unit 32 measures the distance d of each group using the formula 2Δt = 2 (d / c) in “2Δt” calculated for each group. As the distance d in this example, a calculation distance based on the propagation time “2Δt” obtained from “t1” to “t4”, a calculation distance based on the propagation time “2Δt” obtained from “t5” to “t8”, and The calculation distance based on the propagation time “2Δt” obtained from “t9” to “t12” is calculated.

  The verification ECU 4 confirms the validity of communication based on the distance (calculated distance) d measured for each group. Specifically, it is confirmed whether or not the distances d calculated for each group are all equal or within an allowable range. When the verification ECU 4 confirms that the distances d calculated for each set are all equal or within the allowable range, and that the distance d is within the specified value (that is, the electronic key 2 is sufficiently close to the vehicle 1). The distance verification is processed as established. When the verification ECU 4 confirms that the above-described various ID verifications and distance verifications are established, it establishes smart verification.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) Both the vehicle 1 and the electronic key 2 send the UWB radio wave Suwb to each other in a random pattern, and both the vehicle 1 and the electronic key 2 measure the timing information Dti when the UWB radio wave Suwb is sent and received. Are collected in one of the vehicle 1 and the electronic key 2. On the side where the timing information Dti is collected of the vehicle 1 and the electronic key 2, the distance d between the two parties is measured for each set of transmitted and received UWB radio waves Suwb based on the timing information Dti. Thus, in measuring the distance d between the two of the vehicle 1 and the electronic key 2, the UWB radio wave Suwb is transmitted at a different timing each time. For example, a malicious third party copies the UWB radio wave Suwb. Even if it is transmitted by a wireless device or the like, the transmission / reception timing of the UWB radio wave Suwb does not match the normal timing. At this time, since the distances d calculated for each group do not match each other, the distance measurement in this case can be invalidated. Therefore, the distance measurement can be performed at the timing intended by the user. That is, it is possible to enable only distance measurement performed at an opportunity that the user really wants to perform.

(2) Since the radio wave transmitted between the vehicle 1 and the electronic key 2 may be a single pulse (UWB radio wave Suwb), communication control is facilitated.
(3) When the UWB radio wave Suwb is sent between the vehicle 1 and the electronic key 2, it is allowed to cross the radio wave, so that the time required for the exchange of the UWB radio wave Suwb can be shortened. .

  (4) When the electronic key 2 transmits the timing information Dti to the vehicle 1, the timing information Dti is transmitted to the vehicle 1 by encrypted communication. Therefore, it is possible to ensure security when transmitting the timing information Dti to the vehicle 1.

  (5) Before sending the UWB radio wave Suwb, the validity of the pair of the vehicle 1 and the electronic key 2 is confirmed by the pre-authentication unit 33, and on the condition that this pre-authentication is established, the sending of the UWB radio wave Suwb is started. . Therefore, it is advantageous to prevent mistaken opponents when performing distance measurement.

  (6) As shown in “t6” and “t7” shown in FIG. 5, when the transmission / reception timing becomes extremely close, the communication unit of the vehicle 1 or the electronic key 2 switches between transmission and reception. In some cases, the transmission is not completed in time for reception, and the UWB radio wave Suwb cannot be received. In the distance measurement, the distance d changes appropriately depending on the situation, and in what case the UWB radio wave Suwb cannot be received depends on the distance d. Therefore, in the case of distance measurement of this example, by setting transmission / reception of the UWB radio wave Suwb between the vehicle 1 side and the electronic key 2 side at random timing, some of the UWB radio wave Suwb to be transmitted / received can always be transmitted / received. Can be set as follows. If the time when reception cannot be performed by switching between transmission and reception of the wireless device is known, it is clear that radio waves cannot be received as a result of giving priority to transmission. Therefore, in the case of FIG. 5, if “t8−t5” is within the allowable range of “2Δt ± switching cannot be received”, the fact that the UWB radio wave Suwb cannot be received is treated as evidence of the correct distance determination result. You can also.

  (7) As shown in FIG. 7, when the UWB radio wave Suwb is reflected to the vehicle body or the like, so-called multipath, the waveform of the received radio wave is not just one wave, that is, a single pulse, but a plurality of wave clusters. End up. In this case, if the distance is measured using only the first received radio wave r1, the influence of multipath can be ignored. In other words, when a multipath occurs, it interferes with the next radio wave r2, so it is necessary to reduce the communication rate, that is, increase the distance between adjacent pulses. In this case, in order to determine that only the first received wave is received, it is necessary to wait until the interference disappears, so the start of the next communication must be delayed, but this example does not cause this problem. .

  (8) When receiving the UWB radio wave Suwb, the timing information Dti is measured using only the first received pulse. By the way, as described above, when the UWB radio wave Suwb is reflected by the multipath, the received radio wave waveform is received as a plurality of wave clusters and interferes with the next radio wave. For example, the communication rate is lowered. It is necessary to take measures such as this, which leads to a problem that communication throughput is increased. However, in the case of this example, the determination is made using only the first received pulse. This is a countermeasure against multipath, which is advantageous in performing distance measurement more correctly.

  (9) Even if a time shift “ε1” occurs between the time stamps of the timers 37 and 38, “ε1” is canceled in the calculation process of the distance calculation. Therefore, even if there is a time difference between the time stamps of the timers 37 and 38, the distance calculation is not affected at all.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. The second embodiment is an example in which a band rejection filter (BRF) is provided in the UWB radio wave transmission / reception circuit 22. Therefore, the same parts as those in the first embodiment are denoted by the same reference numerals, detailed description is omitted, and only different parts are described in detail.

  FIG. 8A illustrates a frequency spectrum of the UWB radio wave Suwb, and FIG. 8B illustrates a waveform diagram in which the UWB radio wave Suwb is combined with noise. As can be seen from these figures, when the circuit configuration for detecting the envelope of the UWB radio wave Suwb in order to simplify the circuit configuration of the UWB radio wave transmission / reception circuit 22, the UWB radio wave Suwb has a wide band, There is a high possibility of noise. In order to cope with this, it is necessary to receive the UWB radio wave Suwb with power more than noise. That is, if the signal level of the UWB radio wave Suwb is “C” and the noise level is “N”, the UWB radio wave Suwb cannot be received unless the C / N ratio is 0 dB or higher. It becomes necessary to transmit with.

  Therefore, as shown in FIG. 9, the distance measurement system 21 of this example includes a noise removing unit 40 that can remove noise from the UWB radio wave Suwb to improve the C / N ratio of the UWB radio wave Suwb. Noise removal is preferably performed by both the vehicle 1 and the electronic key 2, and in this case, a noise removal unit is provided for both the vehicle 1 (UWB radio wave transmission / reception circuit 22a) and the electronic key 2 (UWB radio wave transmission / reception circuit 22b). 40 is provided.

The noise removal unit 40 includes a filter unit 41 that can remove noise from the received UWB radio wave Suwb, and a filter control unit 42 that removes noise on the UWB radio wave Suwb while optimizing the filter unit 41. The filter unit 41 includes a local oscillator 43 that outputs a certain frequency signal for frequency conversion, a PLL (Phase Locked Loop) 44 that synchronizes input and output of signals in the local oscillator 43, and two signals (first amplifiers 25a and 25b). The image rejection mixer 45 removes the image by synthesizing the output signal and the frequency signal of the local oscillator 43, and the band rejection filter 46 filters the synthesized signal output from the image rejection mixer 45. When the frequency of the output signals of the first amplifiers 25a and 25b is “f”, the image rejection mixer 45 of this example outputs only the f + f _LO side, for example, and the f−f _LO side is the image rejection. It is assumed that it is removed by the mixer 45 or BPF (not shown). The filter control unit 42 is provided on the verification ECU 4 on the vehicle 1 side, and is provided on the key control unit 15 on the electronic key 2 side. The filter control unit 42 switches the band of the filter unit 41 as appropriate by switching the frequency f _LO of the local oscillator 43.

Next, operation | movement of the distance measurement system 21 is demonstrated using FIGS.
As shown in FIG. 10 (a), for example, when the frequency f _LO of the local oscillator 43 is initially set to 2 GHz, the UWB radio wave Suwb has a band of 7.25 to 10.25 GHz in the case of a high band. Therefore, the band is converted to 9.25 to 12.25 GHz. Here, as shown in FIG. 10B, when the stop band of the band rejection filter 46 is 11.75 to 12.25 GHz, if noise exists in the range of 9.75 to 10.25 GHz, Even if the C / N ratio is 0 dB or less, communication for sending UWB radio waves Suwb is established.

As shown in FIG. 11A, when noise cannot be removed and communication is not established, the frequency f _LO of the local oscillator 43 is switched from the initial value of 2 GHz to another value of, for example, 2.5 GHz. Then, in the case of a high band, the UWB radio wave Suwb band is converted to 9.75 to 12.75 GHz. For this reason, as shown in FIG. 11B, when the stop band of the band rejection filter 46 is 11.75 to 12.25 GHz, if noise is present in 9.25 to 9.75 GHz, Can be rejected.

FIG. 12 illustrates a communication sequence of the noise removal operation. When the electronic key 2 receives an LF radio wave (for example, a wake signal Swk or a UHF radio wave is also possible) transmitted from the vehicle 1 during smart communication, the electronic key 2 starts transmitting the UWB radio wave Suwb. At this time, the electronic key 2 transmits the UWB radio wave Suwb at a certain frequency a plurality of times, waits for a certain time after being transmitted a plurality of times, and repeats a series of operations of “several times transmission → transmission standby”. In the example of the figure, the electronic key 2 transmits the UWB radio wave Suwb twice, waits for about several ms, and repeats the series of operations. Incidentally, to transmit the next UWB radio Suwb transmission of UWB radio Suwb Wait few ms is because requires several ms time to switch the frequency f _LO in the local oscillator 43. The reason why the UWB radio wave Suwb is transmitted a plurality of times at one transmission opportunity is to ensure the reliability of communication, and may be any number of times as long as it is one or more times.

On the other hand, the UWB radio wave transmission / reception circuit 22a of the vehicle 1 first sets the frequency f _LO of its own local oscillator 43 to the initial value “f1”. At this time, if the UWB radio wave Suwb of the electronic key 2 can be received by the vehicle 1, communication of the UWB radio wave Suwb is established. Thereafter, the frequency f _LO of the local oscillator 43 of the vehicle 1 is set to “f1”, and communication for subsequent distance matching is executed.

When the communication of the UWB radio wave Suwb is not established with the initial value “f1”, the frequency f _LO of the local oscillator 43 is sequentially switched in the order of “f1 → f2 → f3. For this reason, even if there is noise of a predetermined frequency in the communication environment of smart communication, the noise is removed at any frequency f _LO in the process of sequentially switching the frequency f _LO of the local oscillator 43. For example, if it is confirmed that the C / N ratio is improved when the frequency of the local oscillator 43 of the vehicle 1 is set to “f3”, the frequency of the local oscillator 43 is set to “f3”.

When the noise removal on the vehicle 1 side is completed, the same noise removal operation is executed on the electronic key 2 side. That is, in the UWB radio wave transmission / reception circuit 22b of the electronic key 2, the filter unit 41 is optimized while switching the frequency f _LO of the local oscillator 43 from the initial value, thereby removing noise riding on the UWB radio wave Suwb.

Next, a summary of the noise removal operation will be described using the flowchart shown in FIG.
In step 101, the electronic key 2 (communication processing unit 29b) transmits the UWB radio wave Suwb to the vehicle 1 at a regular or irregular timing (timing to start smart verification).

  In step 102, the vehicle 1 (filter control unit 42) determines whether or not the UWB radio wave Suwb transmitted from the electronic key 2 has been normally received. The determination as to whether or not the UWB radio wave Suwb has been normally received is preferably, for example, a process of confirming whether or not the UWB radio wave Suwb data, that is, a single pulse has been successfully read. If the UWB radio wave Suwb can be normally received, the process proceeds to step 103. If the UWB radio wave Suwb cannot be normally received, the process proceeds to step 105.

In step 103, the filter control unit 42 fixes the frequency f _LO of the local oscillator 43. That is, since the communication of the UWB radio wave Suwb is normally established without being affected by noise, it is assumed that the band of the filter unit 41 is optimal and the frequency f _LO of the local oscillator 43 is maintained at the current value.

  In step 104, the vehicle 1 enters a state in which distance verification communication with the electronic key 2 is started. That is, the vehicle 1 prepares for execution of distance collation communication. Thus, when the band setting of the filter unit 41 is completed, a notification to that effect may be transmitted from the vehicle 1 to the electronic key 2. When the electronic key 2 receives a notification that the band setting of the filter unit 41 is completed from the vehicle 1, the electronic key 2 can stop the transmission of the UWB radio wave Suwb and conversely receive the notification within a predetermined time from the transmission of the UWB radio wave Suwb. If not, the repeated transmission of the UWB radio wave Suwb may be continued.

In step 105, the filter control unit 42 changes the stop band of the filter unit 41 by switching the frequency f _LO of the local oscillator 43. Thereby, the stop band of the filter unit 41 is switched to another range and an attempt is made as to whether or not noise under the communication environment can be removed.

In step 106, the filter control unit 42 determines whether or not the frequency f _LO of the local oscillator 43 is switched a predetermined number of times or less. If the number of times of switching is less than or equal to the predetermined number of times, the process returns to step 101, and it is re-executed whether or not noise can be removed by the filter unit 41 after frequency switching. On the other hand, if the number of times of switching exceeds the predetermined number, it is determined that noise generated in the communication environment cannot be removed, and the process proceeds to step 107.

  In step 107, the filter control unit 42 determines that communication of the UWB radio wave Suwb cannot be performed due to noise. In this case, the user may be notified of this by, for example, voice notification or character display in the vehicle 1 or the electronic key 2.

  This time, by transmitting a UWB radio wave Suwb from the vehicle 1 to the electronic key 2, the same processing as in steps 101 to 107 is performed, and the same noise removal is performed on the electronic key 2 side. When both the vehicle 1 and the electronic key 2 are ready for distance collation communication, distance collation for sending UWB radio waves Suwb to each other is executed. In this distance collation, the distance d between the vehicle 1 and the electronic key 2 can be correctly measured without being affected by noise.

According to the configuration of this embodiment, in addition to (1) to (9) described in the first embodiment, the following effects can be obtained.
(10) By switching the frequency f _LO of the local oscillator 43 of the filter unit 41, the filter unit 41 is optimized by searching the band of the filter unit 41 that is effective against noise generated in the communication environment. As a result, even if noise is generated in the communication environment of the UWB radio wave Suwb, it is possible to eliminate the noise by adjusting the band of the filter unit 41 to a band suitable for the noise, thus ensuring communication feasibility. It is advantageous to do. Moreover, since the filter part 41 is a variable type, it can respond to the noise of a some frequency.

  (11) Since the filter unit 41 is the band rejection filter 46, the band rejection filter 46 can target noise at a certain frequency and accurately remove it.

  (12) Since the UWB radio wave Suwb is transmitted a plurality of times in one transmission from one of the vehicle 1 and the electronic key 2, it is advantageous for ensuring the reliability of the determination. In addition, when the UWB radio wave Suwb is retransmitted a plurality of times, the frequency of the local oscillator 43 is waited for a predetermined time, which is advantageous for ensuring that the UWB radio wave Suwb is received by the other party.

  (13) The filter unit 41 is provided in both the vehicle 1 and the electronic key 2, and the band setting of the filter unit 41 is executed by both the vehicle 1 and the electronic key 2. Therefore, since the filter part 41 of both the vehicle 1 and the electronic key 2 can be optimized, it is further advantageous for ensuring communication establishment.

  (14) When the bandwidth of the band rejection filter 46 is set to, for example, 500 MHz, the UWB radio wave Suwb band (7.25 to 10.25 GHz) is subdivided every 500 MHz for filter setting. For this reason, in setting the filter, it is only necessary to transmit six sets of UWB radio waves Suwb, and the frequency of the local oscillator 43 can be switched five times. Therefore, the filter unit 41 can be optimized only by taking time to switch the frequency of the local oscillator 43 of about several tens of ms. Further, even if the same processing is performed on the electronic key 2 side, the total time required for the filter setting is about 100 ms.

  (15) The noise (narrowband noise) can be removed only by taking a time of “about 100 ms” for the band setting radio wave transmission of the filter unit 41 and a predetermined amount of time for the frequency setting of the local oscillator 43.

  (16) For example, if communication of UWB radio wave Suwb is specialized only for distance measurement, this communication is different in band from the LF band and the UHF band, and therefore distance measurement can be synchronized with bidirectional communication for ID verification. Therefore, even if a sequence for performing distance measurement communication is taken, there is no concern that this becomes a communication waiting time.

(17) When it can be initially determined that no noise is generated in the communication environment, the local oscillator 43 establishes communication at all frequencies f _LO . Therefore, in this case, the communication can be executed such that the filter unit 41 (band rejection filter 46) is not applied at all, for example, the frequency f _LO of the local oscillator 43 is set to “5.0 GHz”.

Note that the embodiment is not limited to the configuration described so far, and may be modified as follows.
In each embodiment, the UWB radio wave Suwb is not limited to a single pulse signal, and may be a signal constructed from a plurality of pulses.

-In each embodiment, prior collation is not necessarily before distance collation, and may be implemented at any time.
In each embodiment, the timing information Dti may be collected in the electronic key 2 instead of the vehicle 1. In this case, the distance verification is performed with the electronic key 2.

In each embodiment, the band of the UWB radio wave Suwb may be a low band.
-In 2nd Embodiment, a noise filter is not limited to a band rejection filter, It can change into another filter.

-In 2nd Embodiment, the structure (circuit structure) of the filter part 41 can be changed suitably other than embodiment.
In each embodiment, the UWB radio wave transmission / reception circuit 22 may include a transmission antenna and a reception antenna separately.

  In each embodiment, the UWB radio wave transmission / reception circuit 22a may be integrated with a transmitter / receiver on the vehicle 1 side (external transmitter 10, in-vehicle transmitter 11, and vehicle receiver 12). The same applies to the UWB radio wave transmission / reception circuit 22b.

In each embodiment, the UWB radio wave Suwb is not limited to being transmitted from a dedicated antenna (communication circuit), and may be transmitted from an antenna already installed in the vehicle 1, for example.
In each embodiment, the distance verification is not limited to being performed before the ID verification, but may be performed during the ID verification or after the ID verification.

-In each embodiment, the timing information Dti should just be the data which understands when transmission / reception of an electromagnetic wave was performed.
In each embodiment, the UWB radio wave Suwb is not necessarily limited to an ultra-wideband radio wave, but refers to a radio wave including frequencies in the vicinity thereof.

  In each embodiment, the electronic key system 3 may include, for example, transmission antennas on the left and right sides of the vehicle body, and determine the position of the electronic key 2 inside and outside the vehicle by looking at the response of the electronic key 2 to radio waves transmitted from these antennas. Good.

In each embodiment, the communication master 19 is not limited to the verification ECU 4 and can be changed to another member as long as it can wirelessly communicate with the communication terminal 20.
In each embodiment, the communication terminal 20 is not limited to the electronic key 2 and can be changed to another terminal.

In each embodiment, the distance measurement system 21 is not limited to being applied to the vehicle 1 but can be applied to other devices and devices.
-In each embodiment, it is good also as a single technical idea only of 2nd Embodiment. That is, in the distance measurement system 21 that measures the distance d between the communication master 19 and the communication terminal 20, on the premise that the UWB radio wave Suwb is used, the frequency f _LO of the local oscillator 43 of the filter unit 41 is switched to change the filter The distance d between the two members may be measured while optimizing the unit 41. In this case as well, distance measurement can be performed at the timing intended by the user.

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Electronic key, 19 ... Communication master, 20 ... Communication terminal, 21 ... Distance measurement system, 29 (29a, 29b) ... Communication processing part, 30 (30a, 30b) ... Timing information measurement part, 31 ... Information collecting unit, 31a ... Information notifying unit as an example of information collecting unit, 31b ... Information acquiring unit as an example of information collecting unit, 32 ... Distance measuring unit, 33 ... Pre-authentication unit, 41 ... Filter unit, 42 ... Filter Control unit 43 ... Local oscillator 46 ... Band rejection filter, d ... Distance, Suwb ... UWB radio wave, Dti ... Timing information, Dti-A ... Transmission timing information, Dti-B ... Reception timing information, Δt (2Δt) ... Propagation time, f _LO ... Local oscillator frequency.

Claims (9)

In the distance measurement system that measures the distance between the communication master and the communication terminal,
A communication processing unit for transmitting and receiving the UWB radio wave in both by communicating the UWB radio wave at random from both the communication master and the communication terminal;
A timing information measuring unit that measures timing information when the UWB radio wave is transmitted and received in each of the communication master and the communication terminal;
An information collection unit that collects the timing information on one side by transmitting the timing information from one of the communication master and the communication terminal to the other;
Based on the timing information collected in one of the communication master and the communication terminal, calculate the propagation time required to send the UWB radio wave to both the communication master and the communication terminal, and based on the propagation time A distance measuring system comprising a distance measuring unit for measuring a distance between two persons. The distance measuring system according to claim 1, wherein the information collection unit transmits the timing information acquired in one of the communication master and the communication terminal to the other by encrypted communication. A pre-authentication unit that confirms the pair validity of the communication master and the communication terminal by wireless communication before sending the UWB radio wave;
The distance measurement system according to claim 1, wherein the communication processing unit starts sending the UWB radio wave on condition that the pre-authentication unit is authenticated. The distance measurement according to any one of claims 1 to 3, wherein the timing information measurement unit measures the timing information using only the first received pulse when receiving the UWB radio wave. system. A filter unit capable of removing noise from the UWB radio wave;
A filter control unit that removes noise from the received UWB radio wave while optimizing the filter unit by switching the frequency of the local oscillator of the filter unit and switching the band of the filter unit;
The distance according to any one of claims 1 to 4, wherein the distance measuring unit measures a distance between the communication master and a communication terminal based on the UWB radio wave after noise removal. Measuring system. The distance measuring system according to claim 5, wherein the filter unit is a band rejection filter. The band setting of the filter unit determines whether or not the UWB radio wave is transmitted a plurality of times in one transmission from one of the communication master and the communication terminal, and at least one of the UWB radio waves can be normally received by the other. If the UWB radio wave can be normally received on the other side, the current value of the local oscillator is maintained and the band of the filter unit is determined. If the UWB radio wave cannot be normally received, the local oscillator frequency is switched. The UWB radio wave is transmitted a plurality of times again to confirm whether or not the UWB radio wave can be received, and the above series of operations is repeated until the UWB radio wave can be normally received. The distance measuring system according to claim 5 or 6, wherein the distance measuring system is optimized. The distance measurement system according to any one of claims 5 to 7, wherein the band setting of the filter unit is executed by both the communication master and the communication terminal. In the distance measurement system that measures the distance between the communication master and the communication terminal,
A filter unit capable of removing noise from UWB radio waves communicated from one of the communication master and the communication terminal to the other;
A filter control unit for removing noise from the received UWB radio wave while optimizing the filter unit by switching a frequency of the local oscillator of the filter unit and switching a band of the filter unit;
A distance measuring system comprising: a distance measuring unit that measures a distance between the communication master and a communication terminal based on the UWB radio wave after noise removal.