JP2013224566A - Unlock device, security system, unlock method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a door from being unlocked by an illegal act.SOLUTION: Each time a code for identifying a portable communication terminal is received, power P(t) of a digital signal in receiving the code is compared with power P(t-1) of a digital signal in receiving another code before receiving the code (step S108). In the case where a difference between the power P(t) and the power P(t-1) is equal to or more than a threshold Th, a determination signal is brought into a low level (step S109) and a demodulation signal which should be outputted to a digital receiver is cut off. Thus, a door of a vehicle is prevented from being unlocked.

Description

  The present invention relates to an unlocking device, a security system, an unlocking method, and a program. More specifically, the present invention includes an unlocking device that receives a code for unlocking a door and unlocks the door, and the unlocking device. The present invention relates to a security system, an unlocking method and a program for receiving a code for unlocking a door and unlocking the door.

  There has been proposed a system that locks and unlocks a door of a vehicle or a house by transmitting identification information individually assigned to the electronic key using wireless communication. In this system, for example, when a user holding an electronic key approaches a door, authentication of identification information is automatically performed. When the authentication is successful, the door can be unlocked. When this type of system is used, it is possible to get on and off the vehicle and enter and exit the house without manually locking and unlocking the door.

  However, since convenience and safety are in a trade-off relationship, it is becoming common for vehicles and houses equipped with the above system to also be equipped with a security system (for example, Patent Document 1 and 2).

  When the communication time between the electronic key and the vehicle is longer than a preset reference time, the system described in Patent Document 1 determines that the driver does not exist in the vicinity of the vehicle, and the door Do not unlock. By using this system, it is possible to establish a communication between the vehicle and the electronic key using the repeater, and to prevent an illegal act of unlocking the door without being noticed by the driver.

  The system described in Patent Document 2 changes the output from the transmission side when communication between the electronic key and the vehicle is performed. In this system, when the receiving side determines that there is no change in the output from the output side, the door is not unlocked. Thereby, fraudulent acts such as unlocking the door using the copied identification information can be prevented.

Japanese Patent No. 3909226 JP 2010-185186 A

  In the system disclosed in Patent Document 1, a circuit and a program for calculating the communication time are newly required. For this reason, the manufacturing cost of a system will increase. In addition, it is difficult to detect a slight difference in communication time. For this reason, it may be considered that an erroneous determination occurs.

  In the system disclosed in Patent Document 2, a circuit and a program for controlling the output on the transmission side are newly required. For this reason, the manufacturing cost of a system will increase. Depending on the user's surrounding environment, the receiving side may be affected by noise or the like. In such a case, it is difficult to accurately detect a change in output.

  The present invention has been made under the circumstances described above, and it is an object of the present invention to accurately prevent door unlocking due to fraud while suppressing an increase in manufacturing cost of the apparatus.

In order to achieve the above object, an unlocking device according to the first aspect of the present invention includes:
Receiving means for receiving a signal modulated based on a code for operating a door locking mechanism from a communication terminal possessed by a user;
Measuring means for measuring a first power at a first time of the received signal and a second power at a second time after the first time;
Power comparison means for comparing the first power and the second power;
Determining means for determining whether or not to unlock the door based on a comparison result by the power comparing means;
Is provided.

The security system according to the second aspect of the present invention is:
An unlocking device according to the present invention;
A communication terminal that outputs a signal modulated based on a code for operating the locking mechanism to the unlocking device;
Have

The unlocking method according to the third aspect of the present invention is:
Receiving a signal modulated based on a code for operating a door locking mechanism from a communication terminal possessed by a user;
Measuring a first power at a first time of the received signal and a second power at a second time after the first time;
Comparing the first power and the second power;
Determining whether to unlock the door based on the comparison result; and
including.

The program according to the fourth aspect of the present invention is:
On the computer,
When a signal modulated based on a code for operating a door locking mechanism is received, a first power of the signal at a first time and a second time after the first time A procedure for measuring the second power;
Comparing the first power and the second power;
A procedure for determining whether or not to unlock the door based on the comparison result;
Is executed.

  According to the present invention, when communication for operating the door locking mechanism is performed between the communication terminal and the unlocking device, for example, the power of the signal when the door is locked and the signal when the door is unlocked Power is compared. Then, based on the comparison result, it is determined whether or not to unlock the door. For this reason, when there is no fixed relationship between the power of the signal at the time of unlocking the door and the power of the signal at the time of locking, the unlocking of the door is prevented. Therefore, it is possible to accurately prevent the door from being unlocked due to fraud. The output signal can be received using an existing device. For this reason, the unlocking of the door due to fraud can be prevented while suppressing an increase in the manufacturing cost of the device.

It is a figure showing roughly the security system concerning a 1st embodiment. It is a block diagram of a portable communication terminal and an unlocking unit. It is a block diagram of a portable control apparatus. It is a figure which shows identification information and a code signal typically. It is a block diagram of a digital receiver. It is a block diagram of a vehicle control device. It is a figure which shows typically communication with a portable communication terminal and an unlocking unit. It is a flowchart which shows a series of processes performed by the determination part. It is a block diagram of the digital receiver which concerns on 2nd Embodiment. It is a figure (the 1) which shows a change curve. It is a figure (the 2) which shows a change curve. It is a flowchart which shows a series of processes performed by CPU.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a security system 10 according to the present embodiment. The security system 10 is a system that automatically unlocks the door of the vehicle 92 when the driver 91 carrying the mobile communication terminal 20 approaches the vehicle 92. As shown in FIG. 1, the security system 10 includes a mobile communication terminal 20 held by a driver 91 and an unlocking unit 30 mounted on a vehicle 92.

  FIG. 2 is a block diagram of the mobile communication terminal 20 and the unlocking unit 30. As illustrated in FIG. 2, the mobile communication terminal 20 includes a transmission device 21, a mobile control device 22, and a reception device 23.

  The receiving device 23 receives an output signal of a short wave band (LF band) transmitted from the unlocking unit 30. Then, the information indicated in the output signal is detected by demodulating the output signal. The receiving device 23 transmits the detected information to the portable control device 22.

  In the present embodiment, the output signal output from the unlocking unit 30 indicates a command for requesting the mobile communication terminal 20 to transmit identification information (hereinafter referred to as an identification information transmission command). Therefore, when the output signal is received by the receiving device 23, an identification information transmission command is transmitted from the receiving device 23 to the portable control device 22.

  The portable control device 22 is a microcomputer that comprehensively controls the portable communication terminal 20. FIG. 3 is a block diagram of the portable control device 22. As shown in FIG. 3, the portable control device 22 includes a CPU (Central Processing Unit) 22a, a main storage unit 22b, an auxiliary storage unit 22c, an interface 22d, and a system bus 22e that connects the above-described units.

  The CPU 22a executes processing to be described later according to a program stored in the auxiliary storage unit 22c.

  The main storage unit 22b has a RAM (Random Access Memory) and the like. The main storage unit 22b is used as a work area for the CPU 22a.

  The auxiliary storage unit 22c has a nonvolatile memory such as a semiconductor memory. The auxiliary storage unit 22c stores a program executed by the CPU 22a and identification information necessary for unlocking the door of the vehicle 92.

  FIG. 4 is a diagram schematically showing identification information and signals corresponding to the identification information. As shown in FIG. 4, the identification information described above is composed of a plurality of (for example, four) codes C1 to C4. The codes C1 to C4 are 6-bit, 8-bit or 16-bit codes having binary values of “0” and “1” as constituent elements. Note that the number of bits of the codes C1 to C4 can be arbitrarily determined.

  The interface 22d connects the transmission device 21 and the reception device 23 to the system bus 22e.

  In the mobile control device 22 configured as described above, when the identification information transmission command is output from the reception device 23, the CPU 22a reads the corresponding identification information from the auxiliary storage unit 22c. Then, a code signal indicating the read identification information is generated and output. As shown in FIG. 4, the code signal is a binary signal, the low level corresponds to the component of the identification information whose value is “0”, and the high level is the identification whose value is “1”. Corresponds to the information component.

  The transmission device 21 frequency-modulates the carrier wave based on the code signal output from the portable control device 22 to generate an output signal. The output signal from the transmitter 21 is a USK band (RF band) FSK (Frequency Shift Keying) signal. The transmitting device 21 outputs the generated FSK signal to the unlocking unit 30.

  Returning to FIG. 2, the unlocking unit 30 includes a digital reception device 31, a vehicle control device 32, a transmission device 33, and a door lock device 34.

  The digital receiver 31 has an antenna provided on the door handle of the vehicle 92. As shown in FIG. 1, the digital receiver 31 has a driver 91 that holds the mobile communication terminal 20 in a region surrounded by a circle C having a radius of about 1 m around the antenna. Next, the FSK signal transmitted from the mobile communication terminal 20 is received.

  FIG. 5 is a block diagram of the digital receiver 31. As illustrated in FIG. 5, the digital reception device 31 includes a frequency conversion unit 41, an A / D conversion unit 42, a D / D conversion unit 43, a detection unit 44, a demodulation unit 45, a determination unit 46, a storage unit 47, and an AND. A gate portion 48 is provided.

  The frequency conversion unit 41 receives the FSK signal via an antenna provided on the door handle, for example. Then, the received FSK signal is converted into an analog signal S1 having a low frequency. In the present embodiment, an FSK signal having a frequency of about 300 MHz is converted into an analog signal S1 having a frequency of about 2.5 MHz.

  The A / D converter 42 converts the analog signal S1 output from the frequency converter 41 into a digital signal S2.

  The D / D conversion unit 43 converts the digital signal S2 into a digital signal S3 suitable for processing by the detection unit 44, the demodulation unit 45, and the determination unit 46.

  The detection unit 44 outputs a binary detection signal S4 that becomes a high level when a code for locking or unlocking the door is detected from the digital signal S3.

  The demodulator 45 demodulates the digital signal S3 and extracts a code indicated by the digital signal S3. The extracted code is notified to the determination unit 46 and the AND gate unit 48. The notification of the code is performed by outputting the demodulated signal S5 generated by demodulating the digital signal S3 to the determination unit 46 and the AND gate unit 48.

  The storage unit 47 has a nonvolatile memory such as a semiconductor memory. The storage unit 47 stores information indicating the power P (t) of the digital signal S3 calculated by the determination unit 46.

  The determination unit 46 calculates the power P (t) of the digital signal S3 output from the D / D conversion unit 43. Then, the power P (t) calculated when the code is notified from the demodulation unit 45 is output to the storage unit 47. As a result, every time a code is notified from the demodulating unit 45, the powers P (t), P (t + 1),... Are sequentially stored in the storage unit 47. Further, every time a code is output from the demodulation unit 45, the determination unit 46 reads information on the existing power P (t−1) stored in the storage unit 47. Next, the calculated latest power P (t) is compared with the power P (t−1) read from the storage unit 47.

  The determination unit 46 is at a high level when the absolute value of the difference between the power P (t) and the power P (t−1) (hereinafter simply referred to as a difference) is less than the threshold Th, and the difference is greater than or equal to the threshold Th. A determination signal S6 that is sometimes at a low level is output.

  The AND gate unit 48 outputs the demodulated signal S5 output from the demodulating unit 45 when the determination signal S6 output from the determining unit 46 is at a high level. Thereby, only when the power P (t) and the power P (t-1) are substantially equal, that is, when the power of the FSK signal output from the mobile communication terminal 20 is substantially constant, the digital receiver 31 Demodulated signal S5 is output.

  FIG. 6 is a block diagram of the vehicle control device 32. As shown in FIG. 6, the vehicle control device 32 has a CPU 32a, a main storage unit 32b, an auxiliary storage unit 32c, an interface 32d, and a system bus 32e that connects the above-described units, like the portable control device 22. Yes.

  The CPU 32a executes a program stored in the auxiliary storage unit 32c.

  The main storage unit 32b has a RAM and the like. The main storage unit 22b is used as a work area for the CPU 22a.

  The auxiliary storage unit 32c includes a nonvolatile memory such as a ROM, a magnetic disk, and a semiconductor memory. The auxiliary storage unit 32c stores a program executed by the CPU 32a. In addition, identification information necessary for unlocking the door of the vehicle 92 is stored in the auxiliary storage unit 32c. This identification information consists of codes C1 to C4.

  The interface 32d connects the digital reception device 31, the transmission device 33, and the door lock device 34 to the system bus 32e.

  The vehicle control device 32 configured as described above instructs the transmission device 33 to transmit an output signal for prompting transmission of identification information. Further, when receiving the detection signal S4 and the demodulated signal S5, the vehicle control device 32 extracts the codes C1 to C2 from the demodulated signal S5. Next, the extracted codes C1 to C2 are collated with previously stored identification information. Then, the vehicle control device 32 notifies the door lock device 34 of a door unlocking command when the identification information composed of the collated codes C1 to C4 and the previously stored identification information all match.

  When instructed by the vehicle control device 32 to transmit an output signal, the transmission device 33 outputs an output signal indicating an identification information transmission command. This output signal is received by the mobile communication terminal 20 only when the mobile communication terminal 20 is located in the area surrounded by the circle C, as can be seen with reference to FIG.

  The door lock device 34 unlocks the door of the vehicle 92 when the door handle is operated by the driver after the door unlock command is notified from the vehicle control device 32.

  FIG. 7 is a diagram schematically illustrating communication between the mobile communication terminal 20 and the unlocking unit 30. As shown in FIG. 7, in the security system 10 configured as described above, when the output signal CM indicating the identification information transmission command is output from the unlocking unit 30 and received by the mobile communication terminal 20, A code C1 constituting identification information is output from the communication terminal 20. Next, when the code C1 output from the mobile communication terminal 20 is received by the unlocking unit 30, an output signal ANS indicating that the command has been received is output from the unlocking unit 30. Next, when the output signal ANS is received by the mobile communication terminal 20, the code C <b> 2 is output from the mobile communication terminal 20. Thereafter, by repeating the above operation, the codes C3 and C4 are output from the mobile communication terminal 20 and received by the unlocking unit 30.

  Next, operations of the determination unit 46 and the AND gate unit 48 when the FSK signal is received in the security system 10 configured as described above will be described with reference to FIG. The flowchart in FIG. 8 corresponds to the processing algorithm of the determination unit 46. The processing shown in this flowchart is executed when the ignition switch of the vehicle is turned off.

  In first step S <b> 101, the determination unit 46 waits for a code output from the demodulation unit 45. When the code is output from the demodulator 45, it is determined whether or not the code is a lock code.

  When the vehicle door is unlocked, the determination unit 46 determines that the received code is a locking code (step S101: Yes). In this case, the determination unit 46 proceeds to step S102.

  In step S102, the determination unit 46 calculates the power P (t) of the digital signal S3. Then, the calculated power P (t) is stored in the storage unit 47.

  In the next step S103, the determination unit 46 determines whether or not a predetermined time has elapsed since the door was locked. When the predetermined time has not elapsed since the door was locked (step S103: No), the determination unit 46 returns to step S101, and repeatedly executes the processing after step S101.

  On the other hand, when the predetermined time has elapsed since the door was locked (step S103: Yes), the determination unit 46 proceeds to step S104.

  In step S104, the determination unit 46 clears the power P (t) stored in step S102.

  In the next step S105, the determination unit 46 sets the level of the determination signal S6 to a high level. Thus, the demodulated signal S5 is output to the vehicle control device 32.

  When the process of step S105 ends, the determination unit 46 returns to step S101 and repeatedly executes the processes after step S101.

  In step S101, when the vehicle door is locked, the determination unit 46 determines that the received code is not a lock code but an unlock code (step S101: No). In this case, the determination unit 46 proceeds to step S106.

  In step S106, the determination unit 46 determines whether or not the received code is an unlock code. When the door of the vehicle is locked and the received code is a code for driving the door lock device 34, the determination unit 46 determines that the received code is an unlock code. (Step S106: Yes). If the vehicle door is unlocked, the determination unit 46 determines that the received code is not an unlocked code (step S106: No).

  If the determination in step S106 is affirmed, the determination unit 46 proceeds to step S107.

  In step S107, it is determined whether or not the power P (t-1) at the time of locking is stored. When the information about the power P (t−1) of the digital signal S3 when the previous code is received is stored in the auxiliary storage unit 32c, the determination in step S107 is affirmed (step S107). : Yes). If the auxiliary storage unit 32c does not store information on the power P (t-1) of the digital signal S3 when the previous code is received, the determination in step S107 is denied. (Step S107: No).

  If the determination in step S107 is affirmed, the determination unit 46 proceeds to step S108.

  In step S108, the determination unit 46 determines whether or not the power P (t) and the power P (t-1) match. Specifically, it is determined whether or not the difference between the power P (t) and the power P (t−1) is less than the threshold Th. When the difference between the power P (t) and the power P (t−1) is equal to or greater than the threshold Th, the determination unit 46 determines that the power P (t) and the power P (t−1) do not match. (Step S108: No). When the difference between the power P (t) and the power P (t-1) is less than the threshold Th, the determination unit 46 determines that the power P (t) and the power P (t-1) match. Judgment is made (step S108: Yes).

  If the determination in step S108 is negative, the determination unit 46 proceeds to step S109.

  In step S109, the determination unit 46 sets the level of the determination signal S6 to a low level. As a result, the demodulated signal S5 output to the vehicle control device 32 is blocked by the AND gate unit 48, and thereafter the door is unlocked. When the process of step S109 ends, the determination unit 46 proceeds to step S103.

  On the other hand, if the determinations in steps S106 and S107 are negative, or if the determination in step S108 is positive, the determination unit 46 proceeds to step S110.

  In step S110, the determination unit 46 sets the level of the determination signal S6 to a high level. Thus, the demodulated signal S5 is output to the vehicle control device 32.

  When receiving the demodulated signal S5, the vehicle control device 32 collates the code indicated in the demodulated signal S5 with the identification information stored in advance. And according to a collation result, the door lock apparatus 34 is notified of the unlocking command of a door. Thereby, the door can be unlocked. In this state, when the door handle of the vehicle is operated, the door is unlocked. When the process of step S110 ends, the determination unit 46 proceeds to step S103.

  As described above, in the digital receiving device 31, every time a code is received, the determination unit receives the power P (t) of the digital signal S3 when the code is received and the other before receiving the code. Is compared with the power P (t−1) of the digital signal S3 when the code is received (step S108). And when the difference of electric power P (t) and electric power P (t-1) is more than threshold value Th, the determination signal S6 from the determination part 46 becomes a low level (step S108). As a result, the demodulated signal S5 to be output to the digital receiver 31 is blocked, and the door unlocking is prevented.

  Therefore, even if a repeater that relays the FSK signal is used due to a criminal act, the power of the FSK signal output from the repeater is different from the FSK signal output from the regular mobile communication terminal 20 The door unlock device 34 is not notified of the door unlock command. Thereby, since the door is not unlocked by mistake, the unlocking of the door by the criminal act can be prevented, and the criminal act can be prevented in advance.

  Further, the power of the FSK signal can be measured using an existing receiving apparatus. For this reason, an increase in the manufacturing cost of the system can be suppressed.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described. The security system 10 according to the first embodiment permits the door to be unlocked only when there is no difference in the power of the FSK signal measured every time a code is received. On the other hand, the security system 10 according to the present embodiment unlocks the door when the change in the power of the FSK signal received when the unlocking code is transmitted follows the action pattern of the driver 91. Allow lock.

  In a vehicle equipped with a smart entry system, communication is performed between a portable communication terminal possessed by a driver and a control device mounted on the vehicle when unlocking the door of the vehicle. When this communication is performed, a driver who tries to get on the vehicle generally approaches the vehicle. In this case, the power of the FSK signal received by the vehicle control device increases with time.

  On the other hand, when the door is unlocked due to a criminal act, the FSK signal from the mobile communication terminal possessed by the driver who moves away from the vehicle is relayed. In this case, the power of the FSK signal decreases with time. Therefore, the security system 10 according to the present embodiment uses the received change in the FSK signal to prevent the door from being unlocked due to a criminal act.

  Hereinafter, the security system 10 according to the present embodiment will be described with reference to the drawings. In addition, about the structure same or equivalent to 1st Embodiment, while using an equivalent code | symbol, the description is abbreviate | omitted or simplified.

  FIG. 9 is a block diagram of the digital reception device 31 constituting the security system 10 according to the present embodiment. As illustrated in FIG. 9, the digital reception device 31 includes a frequency conversion unit 41, an A / D conversion unit 42, a D / D conversion unit 43, a detection unit 44, a demodulation unit 45, and a power detection unit 49. .

  The power detection unit 49 measures the power of the digital signal S3 and outputs a power signal S7 indicating the measurement result to the vehicle control device 32. The detection signal S4, the demodulated signal S5, and the power signal S7 output from the digital receiver 31 are output to the interface 22d of the vehicle control device 32.

  When the detection signal S4 output from the detection unit 44 rises to a high level, the vehicle control device 32 detects the power signal S7 output from the power detection unit 49 until the detection signal S4 falls to a low level. Sample the value. This generates a curve indicating the relationship between the power level of the FSK signal and the time when the code is received.

For example, when the detection signal S4 rises at time t _S and falls at time t _E , a change curve as shown in FIGS. 10 and 11 is generated. The change curve shown in FIG. 10 is a change curve that is seen when the driver 91 carrying the mobile communication terminal 20 approaches the vehicle 92. Further, the change curve shown in FIG. 11 is a change curve that is seen when the driver 91 carrying the mobile communication terminal 20 moves away from the vehicle 92. This change curve is generated every time a code is received by the digital receiver 31.

The vehicle control device 32 extracts the code from the demodulated signal S5 along with the sampling of the power signal S7. Then, the difference between the value of the power signal in the start and end points of the change curve, i.e., the difference ΔP between the power _{P E} of the FSK signal in the power _{P S} and time _{t E} of the FSK signal at time _{t S (=} P E -P _S ) Is calculated. When the difference ΔP is +, the vehicle control device 32 collates the code extracted from the demodulated signal S5 with the identification information stored in advance.

  The vehicle control device 32 sequentially performs the above-described operation, and when the extracted identification information consisting of the codes C1 to C4 and the previously stored identification information all match, the door lock device 34 is instructed to unlock the door. To be notified. Thereby, the door of the vehicle 92 can be unlocked.

  On the other hand, when the difference ΔP is −, the vehicle control device 32 does not collate the code extracted from the demodulated signal S5 with the identification information stored in advance. In this case, the door lock command is not notified to the door lock device 34, and the door of the vehicle 92 remains locked.

  Next, the door unlocking operation in the security system 10 according to the present embodiment will be specifically described with reference to FIG. The flowchart of FIG. 12 corresponds to the processing algorithm of the CPU 32a. The processing shown in this flowchart is executed when the ignition switch of the vehicle is turned off. It is assumed that the door of the vehicle 92 is locked and the counter value n of the CPU 32a is initialized to zero.

  In the first step S201, it is determined whether or not the level of the detection signal S4 is high. When the level of the detection signal S4 is high (step S201: Yes), the CPU 32a proceeds to step S202.

  In the next step S202, the CPU 32a increments the counter value n.

In step S203, the CPU 32a samples the value of the power signal S7 from the power detection unit 49. Thereby, the change curve shown in FIG. 10 or FIG. 11 is calculated. Then, CPU 32a calculates the difference ΔP between the power _{P E} of the FSK signal in the power _{P S} and time _{t E} of the FSK signal at time _{t S (= P E -P S} ).

  In the next step S204, the CPU 32a determines whether or not the difference ΔP is greater than zero. When the difference ΔP is less than zero (step S204: No), the CPU 32a proceeds to step S209, resets the counter value n to zero, and returns to step S201. On the other hand, when the difference ΔP is greater than zero (step S204: Yes), the process proceeds to step S205.

  In step S205, the CPU 32a extracts the code Cn from the demodulated signal S5 and collates the extracted code Cn with previously stored identification information.

  In the next step S206, the CPU 32a determines whether or not the code Cn matches the identification information. If the code Cn and the identification information do not match (step S206: No), the CPU 32a proceeds to step S209, resets the counter value n to zero, and returns to step S201. On the other hand, when the code Cn matches the identification information (step S206: Yes), the CPU 32a proceeds to step S207.

  In step S207, the CPU 32a determines whether or not the counter value n is 4 or more. The identification information is composed of four codes C1 to C4. Therefore, when all four codes are received by the digital receiver 31, the counter value n becomes 4.

  When the counter value n is less than 4 (step S207: No), the CPU 32a returns to step S202. On the other hand, when the counter value n is 4 or more (step S207: Yes), the CPU 32a proceeds to step S208.

  In step S208, the CPU 32a notifies the door lock device 34 of a door unlock command. Thereby, the door can be unlocked.

  In the next step S209, the CPU 32a resets the counter value n to zero. When the process of step S209 ends, the CPU 32a returns to step S201. And the process after step S201 is repeatedly performed.

As described above, in the present embodiment, each time the code is received by the digital receiver 31, FSK signals when the power P _S of the FSK signal at the start of reception of the code, the received code is completed power _{P E} is compared (step S204). Then, than the power _{P S} of at code reception start only if towards the power _{P E} when the code reception completion is large (step S204: Yes), the vehicle door 92 becomes possible unlocking (step S208). On the other hand, towards the power P _S of at code reception start, the case towards the power P _E when the code reception completion is large (step S204: No), unlocking doors of the vehicle 92 is prevented.

  Therefore, even if a repeater that relays the FSK signal is used for criminal acts, unlocking of the door can be prevented, and criminal acts can be prevented.

  Specifically, when a repeater that relays an FSK signal is used due to a criminal act, it is common for a criminal possessing the repeater to follow a driver who moves away from the vehicle 92. . In this case, the power of the FSK signal received by the security system 10 decreases with time as shown in FIG. On the other hand, a driver who intends to unlock the door generally performs the unlocking action with the approach of the vehicle 92. In this case, the power of the FSK signal received by the security system 10 increases with time as shown in FIG.

In this embodiment, only when the power of the FSK signal at the code reception end time t _E is larger than the power of the FSK signal at the code reception start time t _S , the door unlock command is notified to the door lock device 34. Is done. Thereby, since the door is not unlocked by mistake, the unlocking of the door by the criminal act can be prevented, and the criminal act can be prevented in advance.

  As mentioned above, although embodiment of this invention was described, this invention is not limited by the said embodiment. For example, in the above-described embodiment, the case where the identification information is composed of four codes C1 to C4 has been described. However, the identification information is not limited to this, and may include five or more codes. Further, the identification information may be composed of two or three codes.

  As the mobile communication terminal 20 according to the above-described embodiment, a smart key, a smart phone, a communication device that can use wi-fi, and the like are conceivable.

  Although the case where the security system is mounted on an automobile has been described in the above embodiment, the security system according to the present embodiment is also suitable for a house, a condominium, and the like.

  The functions of the devices according to the above-described embodiments can be realized by dedicated hardware or by a normal computer system.

In the above-described embodiment, programs stored in the auxiliary storage unit of the mobile communication terminal 20 and the vehicle control device 32 are a flexible disk, a CD-ROM (Compact Disk Read-Only Memory), a DVD (Digital
A device that performs the above-described processing may be configured by storing and distributing in a computer-readable recording medium such as Versatile Disk (MO) or MO (Magneto-Optical disk) and installing the program in the computer. Good.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. Further, the above-described embodiment is for explaining the present invention, and does not limit the scope of the present invention.

  The unlocking device, the security system, the unlocking method, and the program of the present invention are suitable for preventing the unlocking of the door due to fraud.

DESCRIPTION OF SYMBOLS 10 Security system 20 Portable communication terminal 21 Transmission apparatus 22 Portable control apparatus 22a CPU
22b Main memory 22c Auxiliary memory 22d Interface 22e System bus 23 Receiver 30 Unlocking unit 31 Digital receiver 32 Vehicle controller 32a CPU
32b Main storage unit 32c Auxiliary storage unit 32d Interface 32e System bus 33 Transmission device 34 Door lock device 41 Frequency conversion unit 42 A / D conversion unit 43 D / D conversion unit 44 Detection unit 45 Demodulation unit 46 Judgment unit 47 Storage unit 48 AND Gate unit 49 Power detection unit 91 Driver 92 Vehicle

Claims (8)

Receiving means for receiving a signal modulated based on a code for operating a door locking mechanism from a communication terminal possessed by a user;
Measuring means for measuring a first power at a first time of the received signal and a second power at a second time after the first time;
Power comparison means for comparing the first power and the second power;
Determining means for determining whether or not to unlock the door based on a comparison result by the power comparing means;
An unlocking device comprising: The measuring means measures the first power of the signal received when the door is locked and the second power of the signal received when the door is unlocked;
The power comparing means compares the first power and the second power to calculate a difference between the first power and the second power;
The unlocking device according to claim 1, wherein the determination unit determines whether or not to unlock the door based on a difference between the first power and the second power. The unlocking device according to claim 2, wherein the determination unit determines to unlock the door when a difference between the first power and the second power is within a threshold value.   The unlocking device according to claim 2, wherein the determination unit determines to unlock the door when the second power is larger than the first power.   The unlocking device according to any one of claims 1 to 4, further comprising an unlocking unit that drives the lock mechanism to unlock the door when the determining unit determines to unlock the door. Locking device. An unlocking device according to any one of claims 1 to 5,
A communication terminal that outputs a signal modulated based on a code for operating the locking mechanism to the unlocking device;
Having a security system. Receiving a signal modulated based on a code for operating a door locking mechanism from a communication terminal possessed by a user;
Measuring a first power at a first time of the received signal and a second power at a second time after the first time;
Comparing the first power and the second power;
Determining whether to unlock the door based on the comparison result; and
Unlocking method. On the computer,
When a signal modulated based on a code for operating a door locking mechanism is received, a first power of the signal at a first time and a second time after the first time A procedure for measuring the second power;
Comparing the first power and the second power;
A procedure for determining whether or not to unlock the door based on the comparison result;
A program for running

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