JP2007235308A - Radio apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio apparatus which extends the service life of a battery of a wireless key and a cellular phone without impairing a function (security function) of preventing an electronic device such as the cellular phone from being left behind or stolen, and also to provide its program. <P>SOLUTION: In the radio apparatus, a radio device A(2) repeatedly transmits an identification signal at a predetermined cycle T1 until receiving a response from a radio device B(7). The identification signal to be transmitted at the predetermined cycle T1 from the radio device A(2) has a preamble signal of a predetermined length, and the radio device B(7) repeats an operation of intermittently performing a reception operation at a time interval T2 shorter than the preamble signal of the predetermined length by a time period longer than the predetermined cycle T1, and then, stopping the reception operation during a predetermined time T3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention confirms the presence of each other by performing wireless transmission and reception periodically or irregularly between the wireless key and the main body side device, and when the wireless key and the main body side device exceed a predetermined communication range, The present invention relates to a wireless device that can be used in an authentication device that restricts the function of a side device or generates an alarm.

  In recent years, security systems have been put into practical use in which an operation lock of an electronic device such as a mobile phone or a personal computer is wirelessly controlled in consideration of security.

  As one form of such a security system, in order to prevent the mobile phone from being stolen, a user of the mobile phone possesses an identification signal transmitter in the form of a card, and the mobile phone and the identification signal transmitter are previously connected. There is a mobile phone that can be used when a predetermined identification code is communicated with each other and the identification code is confirmed by both parties (see, for example, Patent Document 1).

  In Patent Document 1 of this wireless two-way communication system, a device (hereinafter referred to as an authentication device) mounted on the main body side such as an electronic device is periodically issued from a portable device (hereinafter referred to as a wireless key). It is described that the authentication ID is received and collated with the ID stored in the authentication device.

And it is described that an M-sequence signal is transmitted every second as a transmission signal. Although there is no particular description as a method for receiving the M-sequence signal, it is necessary to continue the reception operation for one second or more in order to receive the M-sequence signal without the preamble.
JP 2004-143806 A

  However, in the conventional configuration, in order to receive an M-sequence signal transmitted every second, it is necessary to perform a reception operation continuously for one second or more, which increases current consumption and affects battery life. There was a problem of being big.

  The present invention solves the above-described conventional problems. For example, it can extend the battery life of a wireless key, a mobile phone, or the like without losing an electronic device such as a mobile phone or impairing a theft prevention function (security function). An object of the present invention is to provide a wireless device and a program thereof.

  The wireless device A is composed of a wireless device A and a wireless device B, and the wireless device A is a wireless device that repeatedly transmits an identification signal at a predetermined cycle T5 until receiving a response signal from the wireless device B. The identification signal transmitted in the period T5 has a preamble signal of a predetermined length, and the radio B has a time interval T7 shorter than the preamble signal of the predetermined length and a period longer than the T5. It is a wireless device that repeats the operation of pausing the receiving operation for a predetermined time T6 after intermittently performing the receiving operation.

  And it is set as the structure which can perform intermittent reception for the period a little longer than the identification signal transmission interval T5 of the radio | wireless machine A. FIG.

  As a result, the current consumption of the wireless device B can be reduced. Alternatively, the current consumption of the wireless device A can be reduced by increasing the identification signal transmission interval T5 of the wireless device A instead of reducing the current consumption of the wireless device B.

  By using the wireless device and the program of the present invention, the power consumption of the wireless device A and the wireless device B can be reduced, for example, the battery life and misplacement of the wireless key and the convenience of preventing theft can be achieved.

  A first aspect of the invention is a wireless device that includes a wireless device A and a wireless device B, and the wireless device A repeatedly transmits an identification signal at a predetermined cycle T5 until receiving a response signal from the wireless device B. The identification signal transmitted from the wireless device A at the period T5 has a preamble signal having a predetermined length, and the wireless device B has the time interval T7 shorter than the preamble signal having the predetermined length, and The wireless apparatus repeats the operation of pausing the receiving operation for a predetermined time T6 after intermittently performing the receiving operation for a period of time longer than T5.

  And by enabling intermittent reception for a period slightly longer than the identification signal transmission interval T5 of the wireless device A, the current consumption of the wireless device A or the wireless device B can be reduced.

  According to a second aspect of the invention, the wireless device B detects whether the reception signal level of the identification code is equal to or higher than a predetermined level at each time interval T7. If so, the radio apparatus suspends reception until the next reception timing determined by the time T7.

  And the time which has occurred by intermittent reception can be shortened, and the current consumption of the wireless device A or the wireless device B can be further reduced.

  In a third aspect of the invention, the wireless device B performs an operation of detecting a preamble signal for a predetermined time every time interval T7, and continues to receive when the preamble signal is detected within the predetermined time, In the case where the preamble signal cannot be detected within a predetermined time, the radio apparatus interrupts reception and pauses the reception operation until the next reception timing determined by the time T7.

  And the time which has occurred by intermittent reception can be shortened, and the current consumption of the wireless device A or the wireless device B can be further reduced.

  In a fourth aspect of the invention, when the wireless device B receives the identification signal, the wireless device A adds a preamble signal having a predetermined length and transmits a response signal. The wireless device A transmits the identification signal and then transmits a predetermined signal. It is a wireless device that waits for a time and starts receiving from the middle of the preamble signal included in the response signal from the wireless device B.

  Since the time error of the reception timing can be absorbed by the length of the preamble, it can be determined in a short time whether there is a response signal, and the current consumption of the wireless device A can be further reduced.

  According to a fifth aspect of the invention, the wireless device A detects whether or not the reception signal level of the response signal from the wireless device B is equal to or higher than a predetermined level. If there is, it is a wireless device that suspends reception and returns to repeated transmission of period T5.

  Then, it can be determined whether or not there is a response signal in a shorter time, and the current consumption of the wireless device A can be further reduced.

  According to a sixth aspect of the invention, the wireless device A performs an operation of detecting a preamble signal of a response signal from the wireless device B for a predetermined time, and continues receiving when the preamble signal is detected within the predetermined time. In the case where the preamble signal cannot be detected within the predetermined time, the wireless device interrupts reception and returns to repeated transmission of the period T5.

  Then, it can be determined whether or not there is a response signal in a shorter time, and the current consumption of the wireless device A can be further reduced.

  In the seventh invention, after the wireless device A receives the response signal from the wireless device B, both the wireless device A and the wireless device B shift to an authentication mode and periodically perform mutual authentication. An authentication signal is transmitted / received, and an alarm or a lock signal that restricts the function of the device connected to the wireless device A or the wireless device B is output when the reception level is equal to or lower than a predetermined level in the transmission / reception of the authentication signal. Wireless device.

  For example, the battery life and misplacement of the wireless key can be made compatible with the convenience of preventing theft.

  The eighth invention is a program for causing a computer to realize at least a part of the wireless devices of the first to seventh inventions. Since it is a program, at least a part of the present invention can be realized with simple hardware by cooperating hardware resources such as an electric / information device and a computer. In addition, the program can be distributed / updated and installed easily by recording on a recording medium or distributing the program using a communication line.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram of a radio apparatus according to the first embodiment of the present invention.

  1 is a first antenna, 2 is a radio A, 3 is a first transmission / reception means, 4 is a first time control means, 5 is a first authentication means, 6 is a second antenna, 7 Is a radio B, 8 is a second transmission / reception means, 9 is a second time control means, and 10 is a second authentication means. Reference numeral 11 denotes a mobile phone connected to the wireless device.

  The wireless device A is a wireless key, for example, and is carried by the user of the mobile phone 11. Then, when the reception level of the radio wave from the wireless device A becomes weak, the wireless device B restricts the use of the mobile phone 11. In FIG. 1, the mobile phone 11 and the wireless device B are shown separately, but the wireless device B is often built in the mobile phone 11.

  2 and 3 show communication sequences between the wireless device A (2) and the wireless device B (7). FIG. 2 shows a communication sequence in search mode, and FIG. 3 shows a communication sequence in authentication mode.

  The search mode is a mode in which the wireless device A and the wireless device B confirm each other's existence and shift to the authentication mode.

  The authentication mode is a mode in which the wireless device A and the wireless device B regularly communicate with each other in time synchronization to confirm the existence of the other party. The presence of the other party is confirmed in the authentication mode, and the wireless device B does not restrict the use of the mobile phone 11 while receiving radio waves from the wireless device A at a predetermined reception level or higher.

  The search mode communication sequence will be described with reference to FIG.

  Radio A periodically transmits a search signal 12. The time interval for transmitting the search signal 12 is, for example, every 2 seconds. The search signal 12 includes an 8-bit identification code indicating the wireless device A.

  When receiving the search signal 12, the wireless device B transmits a search response 13 to the wireless device A. When the wireless device A receives the search response 13, it transmits a 64-bit Mk signal 14 that is an identification code of the wireless device A. The wireless device B compares the Mk signal 14 with the identification code of the communication partner held in the wireless device B, and transmits a 64-bit MT signal 15 indicating the identification code of the wireless device B if they match. To do.

  Then, the wireless device A transmits a request signal 16, and the wireless device B transmits a challenge signal 17 generated using a random number generator built in the second authentication means 10.

  The wireless device A receives the challenge signal 17, performs encryption processing in the first authentication unit 5, and transmits it as a response signal 18.

  If the wireless device B receives the response signal 18, decrypts the code and transmits the same code as the challenge signal 17, the wireless device B determines that authentication with the wireless device A has been established, and sends a confirmation signal 19 to the wireless device Send to A.

  When the wireless device A receives the confirmation signal 19, it determines that the authentication with the wireless device B has been established. And it transfers to the authentication mode of FIG.

  In shifting to the authentication mode of FIG. 3, the wireless device A starts the timer T1 from the timing at which the response signal 18 is transmitted. The wireless device B takes time synchronization with the wireless device A at the timing when the response signal 18 is received, and starts the timer T1.

  Next, a communication sequence in the authentication mode of FIG. 3 will be described.

  The wireless device A transmits the simple ID signal 20 when the timer T1 is an integer multiple of 4 seconds. The wireless device B performs reception at the timing of the simple ID signal 20 and measures the reception level.

  If the reception level is less than or equal to a predetermined value, the counter built in the second authentication means 10 constituting the wireless device B is incremented assuming that the distance from the wireless device A is more than the predetermined distance. When the counter reaches a predetermined count, a function restriction signal is output to the mobile phone 11.

  If the reception level is equal to or higher than a predetermined level, the counter is cleared. That is, when the reception level of the simple ID from the wireless device A every 4 seconds is continuously below the predetermined level and reaches the predetermined number of times, the use restriction signal is output.

When the timer T1 reaches 32 seconds, the wireless device A transmits a request signal 21. When the timer T1 reaches 32 seconds, the wireless device B also starts reception and receives the request signal 21. Then, the wireless device B creates and transmits a challenge signal 22 using a random number generator.

  The wireless device A starts the timer T1 again at the timing when the request signal 21 is transmitted. When the challenge signal 22 is received, it is determined that authentication has been established, and a pause state is entered.

  When the wireless device A cannot receive the challenge signal, it retransmits the request signal 23 after T2 from the timing of transmitting the request signal 21, and starts the timer T1 again at the timing of transmitting the request signal 23. If the retransmission of the challenge signal 24 cannot be received, the request signal 25 is retransmitted after T3 from the transmission timing of the request signal 23, and the timer T1 is started again at the transmission timing of the request signal 25. A retransmission of the challenge signal 26 is received.

  When the challenge signal 26 cannot be received, the search signal 27 is transmitted after T4 from the timing of transmitting the request signal 24, and the search mode is entered.

  On the other hand, the wireless device B measures the clock error of the wireless device A and the wireless device B at the timing when the request signal 21 is received. Then, the timer T1 is started again.

  Here, a time error between the timer T1 of the wireless device A and the timer T1 of the wireless device B will be considered. When the absolute accuracy of the timepiece is ± 100 ppm, the relative error between the timepieces of the wireless device A and the wireless device B is ± 200 ppm. Therefore, a relative error of ± 6.4 msec (assuming ΔT) occurs at 32 seconds.

  Therefore, when receiving the first request signal 25 that has shifted from the search mode to the authentication mode, the reception is performed 6.4 ms before the timer T1 of the radio B indicates 32 seconds in consideration of the relative error ± 6.4 ms. Need to start. Then, by receiving the request signal 25, the relative error ΔT with the wireless device A can be measured.

  When the relative error ΔT is measured, the reception timing of the next 32 seconds is a time obtained by correcting ΔT from the 32 seconds indicated by the timer T1.

  In the example of FIG. 3, a value obtained by subtracting ΔT from 32 seconds is the reception timing of the next 32 seconds. Since the simple ID 20 is transmitted every 4 seconds, the correction of the reception timing of the simple ID 20 subtracts ΔT × n / 8 from the value of the timer T1. n is the nth reception timing of the simple ID 20. The time error ΔT with the timer T1 of the wireless device A is measured at the next 32 second reception timing and added to the previous ΔT. The above-described correction is performed using ΔT as a result of the addition. Thereafter, this correction process is repeated.

  By performing the above correction processing, it is possible to match the subsequent reception timing of the simple ID 20 and the reception timing of the request signal 21 every 32 seconds or the later-described response signal 18 with the transmission timing of the wireless device A without relative error.

  Actually, reception is performed at a reception timing described later in consideration of a measurement error and a relative error due to a temperature change for 32 seconds. Eliminating the relative error between the timepiece of the wireless device A and the timepiece of the wireless device B can minimize the reception time of the simple ID 20 and greatly contribute to the reduction of current consumption.

  Since there may be retransmission from the wireless device A, reception starts at the timing when the request signal 23 is transmitted.

When the request signal 23 is received, the challenge signal 24 is retransmitted, the clock error of the radio A and the radio B is measured at the timing when the request signal 23 is received, and the timer T1 is started again. Since there may be retransmission from the wireless device A, reception starts at the timing when the request signal 25 is transmitted.

  When the request signal 25 is received, the challenge signal 26 is retransmitted, the clock error of the radio A and the radio B is measured at the timing when the request signal 25 is received, and the timer T1 is started again. Then, reception starts at the timing when the wireless device A transmits the search signal 27, and it is confirmed whether the search signal 27 is present.

  If there is no search signal, it is determined that the wireless device A has received any of the challenge signals 22, 24, and 26, and authentication is established, and the wireless communication device A enters a dormant state.

  If the search signal 27 is received, the search mode is entered. If the search signal 27 is received even though any of the challenge signals 22, 24, 26 is transmitted, the function restriction output is not immediately output to the mobile phone 11 even when the search mode is entered.

  A function restriction signal is output when the sequence of FIG. 2 is not established with the wireless device A within a predetermined time after shifting to the search mode.

  When the authentication is established without shifting to the search mode, the wireless device A transmits the simple ID 20 at the timing when the timer T1 is an integral multiple of 4 seconds.

  The sequence shown in FIG. 3 is repeated. In the next 32 seconds, the response signal 18 and the confirmation signal 19 shown in FIG. 2 are exchanged instead of the exchange of the request signal 21 and the challenge signal 22. In the next 32 seconds, the request signal 21 and the challenge signal 22 are exchanged again.

  FIG. 4 shows transmission / reception timings of the wireless devices A and B in the search mode of FIG. The reception timing will be described with reference to FIG.

  (1) transmits the search signal 12 every T5 at the transmission timing of the wireless device A. T5 is 2 seconds as an example.

  (2) is the reception timing of the wireless device B, and the reception continues for the period T5 + α every T6. T6 is, for example, 10 seconds, and α is 10 milliseconds.

  (3) is an enlarged view of the reception timing of the wireless device B of (2). As shown in (3), the reception of the wireless device B in the T5 + α period is intermittent reception.

  FIG. 5 is a diagram showing a telegram structure of the search signal 12 transmitted by the wireless device A and the reception timing of the wireless device B in the T5 + α period. In FIG. 5, (1) is a telegram structure of the search signal 12, and (2) is a reception timing of the wireless device B.

  The search signal 12 is transmitted in binary FSK. The message structure is composed of a 56-bit preamble consisting of repetition of “0101”, an 8-bit frame synchronization signal, and 8-bit data. The 8-bit data is a so-called identification code.

  The wireless device B performs binary FSK reception, and performs intermittent reception in a reception state for only T11 every T7.

  A reception level check is performed to determine whether or not there is a search signal 12 during the reception period T11. If the result of the reception level check is a predetermined level or less, reception is interrupted. If it is above a predetermined level, reception continues.

  T11 is, for example, a very short time of 200 μsec. T7 is determined by the preamble length of the search signal 12.

  In the example of FIG. 5, since the preamble is 56 bits, if the modulation rate is 9600 bps, the preamble duration is 5.8 ms. The minimum necessary preamble for obtaining the reception synchronization of the search signal 12 is, for example, 32 bits. The 24 bits are additional bits added for intermittent reception. The time length of the additional bits is 2.5 msec, and the intermittent period T7 is 2.5 msec.

  In this way, the wireless device B receives intermittently at intervals shorter than the duration of the preamble, so that the wireless device B always has at least one reception timing during the preamble period of the search signal 12, and is received during the preamble period. The level check can be performed and reception can be continued, so that the frame synchronization signal and data following the preamble can be received.

  In FIG. 5, the current when the radio B is receiving is 12 mA, and the base current when receiving is OFF is 2 mA. The base current is the operating current of the microcomputer.

  As described above, by making the preamble of the search signal 12 longer, the radio B can be intermittently received, and when the search signal 12 cannot be received continuously, the current consumption of the radio B is greatly reduced. it can. Then, the wireless device B performs intermittent reception every T6 for the period of T5 + α.

  Instead of reducing the current consumption of the wireless device B, the current consumption of the wireless device A can also be reduced. In the example of FIG. 5, since reception is performed for 200 μsec every 2.5 msec, even if the base current 2 mA is taken into consideration, the current reduction of the radio B does not perform intermittent reception but continues reception for T5 + α period. Compared to the case, the intermittent reception can be reduced to about ¼.

  That is, when the current consumption of the wireless device B is the same as that in the case of continuous reception during the period T5 + α, the transmission interval of the search signal 12 can be increased four times.

  On the other hand, since the message length of the search signal 12 is simply the addition of 24 additional bits to the preamble, it is 1.5 times the message length of the search signal 12 when the radio B performs continuous reception. It ’s just that. Therefore, the current consumption can be reduced to 1/3 or less by increasing the transmission interval of the search signal 12 by four times.

FIG. 6 shows a message structure and reception timing in a search mode with a search response 13 or lower.
(1) is a message structure transmitted from the transmission side, and (2) is a reception timing on the reception side.

  Hereinafter, an example in which the search response 13 is received will be described.

  When the wireless device B receives the search signal 12, a search response 13 is transmitted. The timing at which the search response 13 is transmitted is promised in advance by the wireless device A and the wireless device B. Radio A starts reception with a delay of T8 from the timing at which search response 13 is transmitted. T8 is set to 1.25 msec, which is a half of 24 bits which are additional bits of the preamble.

The search response 13 does not always return. If the wireless device B does not exist nearby, it will not return. Therefore, it is important from the viewpoint of current reduction that the wireless device A immediately stops receiving when there is no search response 13.

  By configuring to start reception in the middle of the preamble of the search response 13, the wireless device A performs a reception level check in a short time T11 as shown in FIG. it can. Further, it is possible to absorb a variation error within ± 1.25 msec of a reception timing or transmission timing variation error. The modulation / demodulation method is binary FSK.

  Although described in the search response 13, the same applies to other messages in the search mode. The timing of transmission / reception of messages below the search response 13 is determined in advance by the wireless device A and the wireless device B. That is, transmission / reception is performed in a time-synchronized state. Therefore, it can be configured to start reception from the middle of the preamble.

  FIG. 7 shows the message structure and the reception timing of the request signal 21 and the challenge signal 22 which are authentication communication sequences in the authentication mode of FIG.

  The authentication communication sequence is performed every 32 seconds. Therefore, increasing the message length greatly affects the current consumption. Therefore, the request signal 21 and the challenge signal 22 are transmitted by four-value FSK at 9600 bps. That is, the transmission rate is 19200 bps, which is twice the binary FSK.

  In FIG. 7, (1) is a message structure of the request signal 21 or the challenge signal 22 transmitted from the transmission side. (2) is the reception timing on the receiving side. The preamble is 48 bits, the frame synchronization signal is 8 bits, and the data is an identification code or a random number and is 64 bits.

  The preamble is set to the minimum number of bits necessary for receiving synchronization. Therefore, since reception is not possible if reception is set to start in the middle of the preamble, reception is started before request signal 21 or challenge signal 22 is transmitted T9, and request signal 21 or challenge signal 22 is transmitted. wait.

  T9 is, for example, 1 ms. The next 32-second response signal 18 and confirmation signal 19 also have the reception timing shown in FIG.

  Here, the response signal 18 and the confirmation signal 19 in the authentication mode are four-value FSK and have a message structure shown in FIG. On the other hand, the response signal 18 and the confirmation signal 19 in the search mode in FIG. 2 are binary FSK and have the message structure shown in FIG.

  Request signal 23 to challenge signal 26 which are retransmission signals in the authentication mode of FIG. 3 are the message structure and reception timing shown in FIG. 6 and are binary FSK transmissions.

  The search signal 27 is the same as the search signal 12 in FIG. 2 and has the telegram structure shown in FIG. In order to confirm the presence / absence of a retransmission signal, the wireless device B always performs reception as described above.

  By using the reception timing shown in FIG. 6, the presence / absence of a retransmission signal can be detected in a short time, and if there is no retransmission signal, reception can be interrupted immediately, leading to a reduction in current. The reason why the retransmission signal is binary FSK is retransmission, and is not normally transmitted. Therefore, even if the message length is long, current consumption is not affected.

The binary FSK improves the reception sensitivity and the interference disturbance characteristic by about 10 dB compared to the 4-level FSK. That is, by using binary FSK, it becomes resistant to interference and the probability of shifting to the search mode decreases, and as a result, current consumption can be reduced.

  FIG. 8 shows the message structure and reception timing of the simple ID 20 in the authentication mode shown in FIG.

  (1) is the message structure of the simple ID 20 transmitted from the wireless device A, and (2) is the reception timing of the wireless device B.

  It is transmitted with 4-value FSK. Since the preamble is short, it is difficult for the wireless device B to receive 8 bits of data. Reception of the simple ID 20 by the wireless device B only checks the reception level. The reception level check period is performed before and after the simple ID 20 is transmitted. This is because the reception level check is always performed including the period during which the simple ID is transmitted even if there is a time error that occurs due to a clock error between the wireless device A and the wireless device B or processing variations in transmission / reception timing.

  The first transmission / reception means 3 and the second transmission / reception means 8 in FIG. 1 perform wireless transmission / reception. The first time control 4 and the second time control means 9 control transmission and reception timing. The first authentication unit 5 and the second authentication unit 10 determine whether authentication communication is established or whether to output a function restriction signal.

  In addition, the numerical value demonstrated by the said embodiment is an example for demonstrating, and is not limited to this.

  1 described in this embodiment uses hardware resources such as a CPU (or microcomputer), a RAM, a ROM, a storage / recording device, an electric / information device including an I / O, a computer, a server, and the like. You may implement in the form of the program made to cooperate. In the form of a program, new functions can be easily distributed / updated and installed by recording them on a recording medium such as magnetic media or optical media or distributing them via a communication line such as the Internet.

  As described above, the wireless device and the program according to the present invention can provide an electronic device that can achieve both the battery life and misplacement of the wireless key and the convenience of preventing theft, for example. In addition, it can be used in a wireless device that requires low power consumption.

The block diagram of the radio | wireless apparatus in embodiment of this invention Communication sequence diagram in search mode of wireless device in an embodiment of the present invention Communication sequence diagram in authentication mode of wireless device in the embodiment of the present invention Transmission / reception timing chart of wireless device A and wireless device B in the search mode of the wireless device in the embodiment of the present invention Telegram structure and reception timing diagram of search signal of wireless device according to embodiment of present invention Message structure and reception timing chart of search mode of wireless device in embodiment of the present invention Message structure and reception timing chart of search mode of wireless device in embodiment of the present invention Message structure and reception timing diagram of simple ID of wireless device in the embodiment of the present invention

Explanation of symbols

1 First antenna 2 Radio A
3 First transmission / reception means 4 First time control means 5 First authentication means 6 Second antenna 7 Radio B
8 Second transmission / reception means 9 Second time control means 10 Second authentication means 11 Mobile phone

Claims (8)

A wireless device configured by a wireless device A and a wireless device B, wherein the wireless device A repeatedly transmits an identification signal at a predetermined period T5 until receiving a response signal from the wireless device B;
The identification signal transmitted from the wireless device A at the period T5 has a preamble signal having a predetermined length,
The wireless device B intermittently performs a reception operation for a period of time longer than the T5 at a time interval T7 shorter than the preamble signal of the predetermined length, and then pauses the reception operation for a predetermined time T6. A wireless device that repeats operation. The radio B detects whether or not the reception signal level of the identification code is equal to or higher than a predetermined level at each time interval T7, and continues reception if it is equal to or higher than the predetermined level, and interrupts reception if it is lower than the predetermined level. The radio apparatus according to claim 1, wherein the reception operation is suspended until the next reception timing determined by the time T7. The wireless device B performs an operation of detecting a preamble signal for a predetermined time every time interval T7, and continues to receive when the preamble signal is detected within the predetermined time, and the preamble within the predetermined time. 2. The radio apparatus according to claim 1, wherein when the signal cannot be detected, the reception operation is suspended and the reception operation is suspended until the next reception timing determined by time T7. Upon receiving the identification signal, the wireless device B adds a preamble signal having a predetermined length and transmits a response signal, and the wireless device A waits for a predetermined time after transmitting the identification signal. The radio apparatus according to claim 1, wherein reception is started in the middle of the preamble signal included in the response signal from B. The wireless device A detects whether or not the reception signal level of the response signal from the wireless device B is equal to or higher than a predetermined level. If the wireless signal is equal to or higher than the predetermined level, reception is continued. The wireless device according to claim 4, wherein the wireless device returns to the repeated transmission of period T5. The wireless device A performs an operation of detecting a preamble signal of a response signal from the wireless device B for a predetermined time. If the preamble signal is detected within the predetermined time, the wireless device A continues to receive the signal within the predetermined time. 5. The radio apparatus according to claim 4, wherein when the preamble signal cannot be detected, the reception is interrupted and the transmission returns to the repeated transmission of period T5. After the wireless device A receives the response signal from the wireless device B,
Both the wireless device A and the wireless device B shift to an authentication mode, periodically transmit and receive an authentication signal for mutual authentication,
In the transmission / reception of the authentication signal, an alarm or a lock signal for restricting a function of a device connected to the wireless device A or the wireless device B is output when a reception level is a predetermined level or lower. A wireless device according to claim 2 or claim 3. The program for making a computer implement | achieve at least one part of the radio | wireless apparatus of any one of Claims 1-7.

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