JP2008211574A - Communication system, base station and transmitting/receiving device used therefor, and communication method used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system capable of correctly judging a normal request signal even if there exists external noises. <P>SOLUTION: A base station 10 outputs a first request signal of which duration of burst signal is longer than wake code signal. A mobile equipment 20, even if operation is started due to noises, interrupts wake code signal judging process within the period of burst signal transmission time t1, and then restarts receiving of burst signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication system that communicates between a base station and a transmission / reception device, a base station and a transmission / reception device used therefor, and a communication method used therefor.

  Recently, control is performed to automatically open a vehicle door or start an engine by exchanging information between a base station attached to the vehicle and a portable device (key) as a transmission / reception device owned by the driver. The number of vehicles equipped with communication systems is increasing. In such a communication system installed in a vehicle, when information is exchanged between a base station provided in the vehicle and a portable device held by the driver, the portable device is basically prepared for start-up by a burst signal. After that, when the wake code signal is determined, it starts in earnest.

As such a communication system, for example, there is a system disclosed in Patent Document 1, which prevents a non-authorized person from starting an engine of a vehicle. In the communication system, the control device in the vehicle transmits an inquiry signal (request signal) when the start button in the vehicle is pressed, and then checks the identification code group transmitted by the remote control device of the authorized person. . Only when the identification code group matches the predetermined code group, the communication system allows the engine to start. The signal detector connected to the receiving antenna of the remote control device has a reaction threshold level that switches between a high value and a low value. The signal detector relays the inquiry signal and sends it to the next processing stage only when the inquiry signal level is higher than a predetermined reaction threshold.
JP 2001-354117 A

  However, in the conventional communication system, the mobile device always monitors the presence or absence of a request signal, and determines the burst signal included in the request signal when reception of the request signal is started. After determining the burst signal, the portable device is ready to start and enters a mode for receiving a wake code. Therefore, when the mobile device misidentifies the external noise as a burst signal, the mobile device enters a mode for receiving a wake code, and there is a problem that even if a normal burst signal is received thereafter, the burst signal cannot be judged well.

  The present invention has been made to solve the conventional problems, and provides a communication system that can correctly determine a legitimate request signal even in the presence of external noise, and a base station and a mobile device used for the communication system. An object is to provide a communication method to be used.

  The base station of the present invention is a base station that transmits a request signal including at least a burst signal and a code signal following the burst signal to a transmission / reception device, a transmission unit that transmits the request signal to the transmission / reception device, and the transmission / reception A receiving unit that receives a response signal corresponding to the request signal from a device, and a control unit that outputs the request signal to the transmitting unit and that receives the response signal via the receiving unit, and The control unit outputs a first request signal that is a request signal in which the transmission time of the burst signal is set longer than the transmission time of the code signal.

  With this configuration, it is possible to transmit a request signal so that the transmission / reception apparatus side can correctly receive even under noisy environments.

  In the base station of the present invention, the control unit sets the transmission time of the burst signal to be longer than a timeout time that is a reception waiting time of the code signal in the transmission / reception apparatus, and transmits the code signal. A first request signal which is a request signal whose time is set shorter than the timeout time is output.

  With this configuration, it is possible to transmit a request signal so that the transmission / reception apparatus side can correctly receive even under noisy environments.

  In the base station of the present invention, the control unit outputs a second request signal that is a request signal in which a transmission time of the burst signal is set shorter than the timeout time, and the second request signal The first request signal may be output when a response signal is not detected within a predetermined time after transmitting.

  With this configuration, it can operate at high speed and low power in an environment with low noise, transmit a request signal with a long burst signal in an environment with high noise, and reliably prevent malfunction even in an environment with high noise. .

  The transmitting / receiving apparatus of the present invention is a transmitting / receiving apparatus that receives a request signal including at least a burst signal and a code signal following the burst signal from a base station, wherein the first receiving antenna, the second receiving antenna, A reception unit that receives the request signal via the first reception antenna and the second reception antenna, and the reception unit receives signals received by the first reception antenna and the second reception antenna. The antenna switching unit that detects the signal level of the signal and selects one of the signal levels that is high, and the signal is received by one of the first reception antenna and the second reception antenna selected by the antenna switching unit. A code signal determination unit that performs signal determination, and the transmission time of the burst signal is the reception waiting time of the code signal in the transceiver It is set longer than a certain time-out time, and when the second receiving antenna receives an unnecessary signal from the outside, the antenna switching unit selects the second receiving antenna, and the receiving unit receives the burst signal. Transition to the receiving mode, and based on the interruption of the unnecessary signal from the outside, the receiving unit shifts to the mode for receiving the code signal, and the timeout time elapses from the transition to the mode for receiving the code signal Thereafter, the receiving unit shifts to a mode for receiving the burst signal, and the antenna switching unit selects the first receiving antenna when the first receiving antenna receives the burst signal.

  With this configuration, the request signal can be correctly received even in an environment where there is an unnecessary signal such as noise from the outside.

  A communication system according to the present invention includes a base station that transmits a request signal including at least a burst signal and a code signal following the burst signal, and a transmission / reception device that receives the request signal and changes a reception mode. The base station transmits a first request signal, which is a request signal in which a transmission time of the burst signal is set longer than a transmission time of the code signal, to the transmission / reception device, and the code signal The transmission / reception apparatus set to the mode for receiving the signal shifts to the mode for receiving the burst signal based on the elapse of the timeout time.

  With this configuration, it is possible to provide a communication system capable of correctly communicating between a base station and a transmission / reception device even in an environment with noise.

  In the communication system of the present invention, the base station sets the transmission time of the burst signal to be longer than a timeout time that is a reception waiting time of the code signal in the transmission / reception apparatus, and transmits the code signal. A first request signal which is a request signal whose time is set shorter than the timeout time is output.

  With this configuration, it is possible to provide a communication system capable of correctly communicating between a base station and a transmission / reception device even in an environment with noise.

  In the communication system of the present invention, the base station outputs a second request signal which is a request signal in which the transmission time of the burst signal is set longer than the timeout time, and the second request signal The first request signal may be output when a response signal is not detected within a predetermined time after transmitting.

  With this configuration, it can operate at high speed and low power in an environment with low noise, transmit a request signal with a long burst signal in an environment with high noise, and reliably prevent malfunction even in an environment with high noise. .

  Further, the communication method of the present invention is a communication method for performing communication between a base station and a transmission / reception device, wherein the base station includes a burst signal and a code signal following the burst signal, and the transmission time of the burst signal is , Executing a step of transmitting a first request signal, which is a request signal set longer than a transmission time of the code signal, to the transmission / reception device, the transmission / reception device based on an unnecessary signal from the outside, The step of shifting to the mode for receiving the signal, the step of shifting to the mode for receiving the code signal based on the interruption of the unnecessary signal from the outside, and the step of receiving the first request signal are executed.

  By this procedure, it is possible to provide a communication method capable of correctly communicating between the base station and the transmission / reception apparatus even in an environment where there is an unnecessary signal such as noise from the outside.

  In the communication method of the present invention, the base station sets a transmission time of the burst signal to be longer than a timeout time which is a reception waiting time of the code signal in the transmission / reception apparatus, and the transmission time of the code signal Executing a step of outputting a first request signal which is a request signal set shorter than the timeout time, and after the timeout time elapses from the time when the transmission / reception apparatus shifts to a mode of receiving the code signal, A step of shifting to a mode for receiving a burst signal is executed.

  By this procedure, it is possible to provide a communication method capable of correctly communicating between the base station and the transmission / reception apparatus even in an environment where there is an unnecessary signal such as noise from the outside.

  In the communication method of the present invention, the base station includes a code signal and a burst signal preceding the code signal before transmitting the first request signal to the transmission / reception apparatus, and the transmission time of the burst signal May further execute a step of transmitting a second request signal, which is a request signal set to be shorter than a timeout time that is a reception waiting time of the code signal in the transmission / reception apparatus, to the transmission / reception apparatus.

  With this procedure, it can operate at high speed and with low power in an environment with low noise, send a request signal with a long burst signal in an environment with high noise, and reliably prevent malfunction even in an environment with high noise. .

  The present invention provides a communication system that can correctly determine a legitimate request signal even when there is an unnecessary external signal such as external noise, a base station and a transmission / reception apparatus used therefor, and a communication method used therefor.

  Hereinafter, a communication system according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
A communication system according to a first embodiment of the present invention is shown in FIG.

  In FIG. 1, the communication system 1 is configured to include a base station 10 provided in a vehicle and a portable device 20 possessed by a driver. Further, a noise source 30 exists in the vicinity of the communication system 1 as an external noise source for the communication system 1. The portable device 20 includes, for example, a vehicle key, but a specific example is not particularly limited. In this example, the communication partner of the base station 10 is a portable device, but is not limited to a portable device, and may be a general transmission / reception device.

  The base station 10 includes a control unit 11, a transmission unit 12 and a reception unit 15 connected to the control unit 11. The transmission unit 12 is connected to a first transmission antenna 13 and a second transmission antenna 14 formed by loop coils. In the figure, the first transmission antenna 13 has a coil wound in the left-right direction, and the second transmission antenna 14 has a coil wound in a direction perpendicular to the paper surface. This indicates that the directivity of the two transmission antennas, particularly the relative directivity with respect to the mobile device 20 of the communication partner is different. However, since the relative directivities of the two transmitting antennas with respect to the portable device 20 are different depending on the installation location of the antennas, it is not essential to change the winding method of the coils. That's fine. In the present embodiment, the directivity difference is not essential.

  When communicating with the mobile device 20, the base station 10 outputs a request signal for requesting an answer from the mobile device 20 from the transmission antenna 13 or 14, including a wake code signal and a burst signal. Here, for convenience of explanation, description is made using two antennas, but actually, three or more antennas may be used.

  The receiving unit 15 is connected to the receiving antenna 16 and receives a signal from the portable device 20 via the receiving antenna 16.

  As will be described later, the control unit 11 performs control so that a request signal including at least a burst signal and a wake code signal following the burst signal is output via the transmission unit 12 and the transmission antenna 13 or 14. The request signal is a signal for the base station 10 to authenticate the mobile terminal 20, and the mobile terminal 20 shifts to various different modes according to the content of the wake code signal of the request signal. Further, the determination result from the base station 10 is received using the receiving unit 15 and the receiving antenna 16 connected to the receiving unit 15, and the subsequent control is changed according to the result.

  The burst signal is a signal for starting up the receiving unit 22, in particular, the circuit operation of the portable device 20 in the sleep mode (standby state) when the power is on but the receiving unit 22 is not particularly operating. The portable device 20 is shifted to the operation mode. The burst signal contains no code and is not modulated at all. The burst signal is composed of a continuous on signal of, for example, 2 ms or more, and generates starting power in a circuit constituting the receiving unit 22 by the action of electromagnetic induction or the like. However, the form is not particularly limited.

  The wake code signal is a code signal transmitted after the burst signal, and includes a meaningful code. The burst signal and the wake code signal constitute a request signal for requesting some answer from the portable device 2. The wake code signal includes, for example, a signal that an ON signal of 150 μs indicates “bit 0” and an ON signal of 300 μs indicates “bit 1”. The receiving unit 22 of the portable device 20 determines the meaning of the code of the wake code signal and determines whether or not the subsequent operation can be continued. That is, the wake code signal is a signal for starting the determination operation of the receiving unit 22. In this example, the wake code signal is composed of an AM-modulated signal in the 125 kHz band, but the frequency band and modulation method are not particularly limited.

  On the other hand, the portable device 20 includes a control unit 21, a reception unit 22, a reception antenna 23 and a reception antenna 24 connected to the reception unit 22, a transmission unit 25, and an antenna 26 connected to the transmission unit 25.

  The request signal transmitted from the transmission antenna 13 or the antenna 14 of the base station 10 is received by the reception antennas 23 and 24. The receiving antennas 23 and 24 are formed of loop coils, and when a request signal is received, an induced voltage is generated according to the received electric field strength and input to the receiving unit 22. The directivities of the reception antennas 23 and 24 are also different from those of the first transmission antenna 13 and the second transmission antenna 14, but are not essential in the present embodiment.

  The receiving unit 22 includes an antenna switching unit 221 that enables one of the receiving antennas 23 and 24 according to the received signal level, a demodulating unit 222 that demodulates the received AM-modulated request signal into a digital signal, and a demodulating unit. A wake code signal determination unit 223 that determines whether or not the digital signal demodulated in 222 matches a predetermined code, and transmits a determination result notification signal to the control unit 21 if it matches.

  In response to the determination result notification signal from the wake code signal determination unit 223, the control unit 21 transmits a response signal using, for example, a 300 MHz band radio wave via the transmission unit 25 and the transmission antenna 26 connected to the transmission unit 25. Is transmitted to the base station 10.

  FIG. 2 shows the waveform of the request signal and the noise signal from the noise source 30 according to the present embodiment.

  2A is a diagram showing an induced voltage waveform when the request signal S1 is received in the present embodiment, and FIG. 2B is a diagram showing an example of a noise waveform when the noise signal S2 is received. FIG. 8C is a diagram showing an induced voltage waveform S3 when the request signal S1 is received in a noise environment (under reception of S2). Further, (d) is a diagram showing an induced voltage waveform when the conventional request signal S4 is received, and (e) is a diagram showing an example of the noise waveform when the noise signal S5 is received in the conventional communication system. (F) is a diagram showing an induced voltage waveform S6 when the request signal S4 is received under a noise environment (under reception of S5).

  T1 shown in FIG. 2 (c) is the transmission time of the burst signal 51g (burst signal transmission time), and t3 receives the wake code signal from the base station 10 after the induction voltage waveform S3 ends. Until this time, it is a time (wake code signal reception timeout time) for waiting for reception of the wake code signal, which is registered in the portable device 20 in advance. t2 is the transmission time of the wake code signal 52g (wake code signal transmission time). In this example, the relationship t2 <t3 <t1 is established. Further, t5 is a time for transmitting the burst signal 51g after the elapse of the wake code signal reception timeout time t3. The length of t5 is arbitrary, but at least t5 must be present, and t5> 0.

  FIG. 3A is an enlarged view of the waveform of the request signal in FIG. 2 and is a 125 kH modulated signal. On the other hand, FIG. 3B shows an enlarged waveform of noise in FIG. 2 and is a random signal with an indefinite frequency.

  Here, regarding the situation when the mobile terminal 20 receives a request signal from the base station 10 under a noisy environment, the conventional signals (d), (e), and (f) in FIG. 2 are assumed. In this case, first, the receiving unit 22 of the portable terminal 20 receives the noise signal S5 as a request signal (burst signal). For example, when the receiving antenna 23 of the receiving unit 22 is arranged to face the transmitting antenna 13 and the receiving antenna 24 is arranged to face the noise source 30, the antenna switching unit 221 The receiving antenna 24 having a high signal level is selected, and the receiving unit 22 receives the noise signal S5. In the following description, it is assumed that the receiving antenna 24 is selected.

  At this time, the receiving unit 22 recognizes the long part 54b of the signal as a burst signal and starts the operation, and performs the reception determination of the wake code signal after the period of the signal part 55b after the end of the part 54b. . Even if the normal burst signal 51a is transmitted during that period, the receiver 22 recognizes the burst signal 51b as a part of the wake code signal and processes it, so that the induced voltage of the request signal S4 is the noise signal S5. Even if it is much higher than the induced voltage, it is determined as a communication error.

  Therefore, in this embodiment, as shown in the request signal S1, the transmission time t1 of the burst signal is made longer than the transmission time t4 of the conventional burst signal (FIG. 2 (f)), and the transmission time t1 of the burst signal is set. In the middle, the wake code signal reception timeout time t3 expires. In particular, the transmission time t1 of the burst signal is set longer than the timeout time t3 that is the reception waiting time of the wake code signal.

  At this time, the induced voltage waveform of the antenna 24 when the portable device 20 receives the request signal S1 and the noise signal S2 is as shown in S3. At this time, the receiving unit 22 regards the long portion 54d of the signal as a burst signal and starts the operation (burst signal reception start; burst signal reception mode). Then, the end (off) of the signal portion 54d is detected, and the process shifts to a wake code signal reception process (wake code signal reception mode), and after the period of the subsequent signal portion 55d, the completion of reception of the wake code signal is determined. . The antenna 24 receives the burst signal 51d from the middle, but the burst signal 51d is not determined as a code by the wake code signal determination unit 223. Therefore, the wake code signal determination unit 223 cannot complete wake code reception within the wake code signal reception timeout time t3, and the reception unit 22 returns to the burst signal waiting state.

  On the other hand, since the mobile device 20 continuously receives the burst signal 51d, the reception unit 22 starts the reception operation again during the remaining period t5 of the burst signal period 51d, and executes the process of waiting for burst signal reception interruption. The burst signal reception interruption is detected at the head of the wake code signal 52d, and the wake code signal 52d can be received correctly.

  The operation of the communication system configured as described above will be described with reference to FIG.

  First, the mobile device 20 stands by in a burst signal waiting state (step S301). Here, when the receiving unit 22 of the mobile device 20 determines whether there is a request signal from the base station 10 and determines that there is no request signal from the base station 10 (step S301; NO), step S301 is repeatedly executed. And waits for a request signal from the base station 10.

  On the other hand, when it is determined in step S301 that the receiving unit 22 has received the request signal from the base station 10 (step S301; YES), reception of the burst signal is started (step S302). Here, in the first determination, the mobile device 20 determines the first 54d portion of the noise signal S3 shown in FIG. 2C as a burst signal, and starts receiving the burst signal.

  The receiving unit 22 includes an AGC (Automatic Gain Control) circuit, and the antenna switching unit 221 of the receiving unit 22 switches between the receiving antenna 23 and the receiving antenna 24 and detects each signal level. The antenna with the higher signal level is selected (step S303). Here, as described above, since the first burst signal is received with respect to a noise signal having a relatively high level, the reception antenna (second reception antenna) 24 that receives this noise signal is selected.

  Thereafter, the receiving unit 22 determines whether or not the burst signal has been interrupted (step S304). If it is determined that the burst signal has not been interrupted (step S304; NO), step S304 is repeatedly executed to interrupt the burst signal. wait. Here, the transmission time t1 of the burst signal may be equal to or longer than the time until the AGC operation and the antenna selection are completed after the reception unit 22 starts receiving the burst signal, for example, a continuous transmission signal of 2 ms or more. It is.

  On the other hand, if it is determined in step S304 that the burst signal has been interrupted, the demodulation circuit 222 of the receiving unit 22 converts the signal 55d input following the burst signal into a 1/0 bit data string, and the wake code signal (Step S305). The wake code signal determination unit 223 determines whether reception of the wake code signal has been completed (step S306). If it is determined that reception of the wake code signal has not been completed (step S306; NO), a predetermined timeout It is determined whether the time has elapsed (step S307), and when it is determined that the predetermined timeout time has not elapsed (step S307; NO), the process returns to step S305, and the receiving unit 22 continues to receive the wake code signal.

  Then, the wake code signal determination unit 223 determines again whether reception of the wake code signal is completed (step S306). In this case, even if the receiving antenna 23 of the receiving unit 22 receives the normal burst signal 51d from the transmitting antenna 13 of the base station 10 from the middle, the burst signal 51d is in the reception mode of the wake code signal. The wake code signal determination unit 223 cannot determine the code, and the determination in step S306 is NO. Further, the wake code signal determination unit 223 determines whether or not a predetermined timeout time has elapsed (step S307), and if the reception of the wake code signal cannot be completed within the wake code signal reception timeout time t3, the predetermined timeout time is reached. (Step S307; YES), it is determined as a reception error, the process returns to step S301, and waits in a burst signal waiting state. Here, when the wake code signal determination unit 223 of the reception unit 22 determines the wake code, the mobile device 20 receives the noise signal S2, recognizes the long signal portion 54d as a burst signal, and starts operation. However, since the subsequent signal portion 55d does not match the wake code, the control circuit 21 does not operate to prevent malfunction and reduce current consumption.

  After returning to step S301 again, since the reception antenna 23 of the mobile device 20 continues to receive the burst signal 51d from the transmission antenna 13 of the base station 10, the reception unit 22 performs the remaining period t5 of the burst signal period 51d. The reception operation is started again (step S302), and the antenna switching unit 221 switches between the reception antenna 23 and the reception antenna 24, detects the respective signal levels, and selects the antenna with the higher signal level (step S303). Here, as described above, since the reception antenna 23 has received the burst signal 51d having a relatively high level, this reception antenna 23 (first reception antenna) is selected.

  Thereafter, the receiving unit 22 determines whether or not the burst signal has been interrupted (step S304). If it is determined that the burst signal has not been interrupted (step S304; NO), step S304 is repeatedly executed to interrupt the burst signal. wait.

  On the other hand, when the receiving unit 22 determines in step S304 that the burst signal has been interrupted (step S304; YES), the receiving unit 22 receives the wake code signal that is the first half of the request signal that is input following the burst signal. 52d is received (step S305). Here, the demodulator 222 converts the wake code 52d into a bit data string of 1/0 by the demodulator 222, and the wake code signal determination unit 223 determines the wake code 52d. In this embodiment, a short pulse (for example, 0.5 ms or less) is determined as bit 0, and a long pulse (for example, 0.5 ms or more) is determined as bit 1.

  The wake code signal determination unit 223 determines whether reception of the wake code signal has been completed (step S306). If it is determined that reception of the wake code signal has not been completed (step S306; NO), a predetermined timeout time is set. It is determined whether or not a predetermined time-out period has elapsed (step S307; NO), the process returns to step S305, and the wake code signal is continuously received. Here, the wake code signal determination unit 223 determines whether reception of the wake code signal is completed by determining whether a predetermined number of bits has been received.

  On the other hand, when the wake code signal determination unit 223 determines in step S307 that the predetermined timeout time has elapsed (step S307; YES), the reception cannot be completed even after the predetermined timeout time has elapsed, and it is determined as a reception error. Then, the process returns to step S301 and waits in a burst signal waiting state.

  In step S306, when it is determined that the wake code signal determination unit 223 has received the predetermined number of bits (step S306; YES), it is assumed that reception of the wake code signal is completed, and the wake code signal determination unit 223 receives the signal. If the received wake code is not a regular code (step S308; NO), the process returns to step S301 and waits in a burst signal waiting state. To do. Here, since the burst signal reception interruption is detected at the head of the wake code signal 52d and the wake code signal 52d is received, the wake code signal can be correctly received.

  On the other hand, when it is determined in step S308 that the received wake code is a regular code (step S308; YES), the wake code signal determination unit 223 notifies the control unit 21 of the determination result (step S309), and the control unit 21 starts driving upon reception of the notification signal, determines whether to receive the code signal 53d after the wake code signal 52f, and transmits a response signal to the base station 10 via the transmission unit 25 according to the determination result. (Step S310). Then, the process ends.

  Thus, in the present invention, the burst signal transmission time t1 is set longer than the wake code reception waiting time-out time t3 (t3 <t1). Therefore, even if the receiving unit 22 of the mobile device 20 starts to operate due to noise, the wake code signal determination process is once ended within the burst signal transmission time t1, the burst signal reception is started again, and the reception signal level is large. Since an antenna can be selected, malfunction under a noisy environment can be prevented. In FIG. 2, the start point of the wake code reception waiting time-out time t3 comes before the start point of the burst signal transmission time t1. However, since the time-out time of the wake code signal starts to be counted before the start of reception of the normal burst signal, the burst signal transmission time t1 is set longer than the wake code reception waiting time-out time t3. A timeout always occurs during the reception of the burst signal.

  Also, the wake code reception waiting time-out period t3 must not expire before receiving all the wake code signals. Therefore, the wake code reception waiting time-out time t3 must be longer than at least the wake code signal transmission time t2. Therefore, the relationship t2 <t3 is established.

  In the present embodiment, the receiving unit 22 continues to wait until the reception of the burst signal is interrupted. Therefore, the burst signal may be further lengthened. If this is the case, the correct operation will be ensured in a noisy environment.

  In the above description, the example in which the base station side and the portable device side each have two antennas has been described. However, the present invention can be similarly implemented even if the base station side and the portable device side each have one antenna.

(Second Embodiment)
In this embodiment, in order to reduce the burden on the circuit due to the transmission of a long burst signal each time, communication is first performed with a short burst signal as in the prior art, and only when the communication is not established, the burst signal is This is an example of lengthening.

  The configuration of the communication system of this embodiment is the same as that of the first embodiment shown in FIG.

  The operation of the communication system of this embodiment will be described with reference to FIG. Here, the operation on the base station 10 side will be mainly described. The operation on the mobile terminal 20 side is basically the same as that described in the first embodiment.

  First, the base station 10 transmits a second request signal in which the transmission time of the burst signal is shorter than the transmission time of the wake code signal as in the prior art (step S401), and whether or not the response signal from the mobile device 20 has been received. Judgment is made (step S402). The transmission time of the second request signal may be t4 shown in FIG. 2 (f), for example. When it is determined that the base station 10 has not received a response signal (step S402; NO), it is determined whether a predetermined time has elapsed (step S403), and when it is determined that the predetermined time has not elapsed (step S403). Step S403; NO), returning to Step S402, it is determined again whether the response signal from the portable device 20 has been received. Here, when the mobile device 20 can correctly receive the request signal from the base station 10, it sends a response signal to the base station 10. Therefore, the base station 10 determines whether the mobile device 20 has received this response signal. Determines whether the request signal has been correctly received.

  On the other hand, when it is determined in step S402 that the base station 10 has received the response signal from the portable device 20 (step S402; YES), it is determined that the portable device 20 has correctly received the request signal, and the transmission interval of the request signal is determined. Is determined (step S405), and when it is determined that the predetermined time that is the transmission interval of the request signal has not elapsed (step S405; NO), step S405 is repeatedly executed, Wait for a predetermined time.

  On the other hand, if it is determined in step S405 that a predetermined time, which is the request signal transmission interval, has elapsed (step S405; YES), the process returns to step S401, and the second request signal is transmitted again.

  When it is determined in step S403 that the predetermined time has elapsed (step S403; YES), the base station 10 correctly receives the request signal from the base station 10 even if the predetermined time has elapsed. The first request signal is transmitted assuming that it was not possible (step S404). The first request signal transmitted at this time is the first request signal in which the transmission time of the burst signal is longer than the transmission time of the wake code signal. For example, the burst signal having the transmission time t1 described in the first embodiment may be used. .

  After the base station 10 transmits the first request signal, it is determined whether a predetermined time that is the transmission interval of the request signal has elapsed (step S405), and the predetermined time that is the transmission interval of the request signal has elapsed. If it is determined that there is not (step S405; NO), step S405 is repeatedly executed to wait for a predetermined time.

  On the other hand, if it is determined in step S405 that a predetermined time, which is the request signal transmission interval, has elapsed (step S405; YES), the process returns to step S401, and the second request signal is transmitted again.

  In this way, the base station first communicates with a short burst signal, and transmits a request signal with a longer burst signal only when a response signal cannot be received even after a predetermined time has elapsed. Accordingly, it is possible to operate with high speed and low power in an environment with little noise, transmit a request signal with a long burst signal in an environment with high noise, and reliably prevent malfunction even in an environment with high noise.

  The present invention is useful for a communication system between a base station and a portable device that is easily affected by external noise, such as a vehicle remote control device, but the application example is not particularly limited.

  Although various embodiments of the present invention have been described, the present invention is not limited to the matters shown in the above-described embodiments, and those skilled in the art may modify or apply the description based on the description of the specification and well-known techniques. The present invention is intended to be included in the scope for which protection is sought.

  As described above, according to the communication system according to the present invention, it is possible to correctly determine a legitimate request signal in a mobile terminal even when there is external noise.

1 is a block diagram of a communication system according to a first embodiment of this invention. The figure which shows the waveform of the request signal and noise in the 1st Embodiment of this invention The figure which shows a mode that the request signal and noise signal in FIG. 2 were expanded. The flowchart for demonstrating operation | movement of the portable apparatus of the communication system in the 1st Embodiment of this invention. The flowchart for demonstrating operation | movement of the base station of the communication system in the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication system 10 Base station 11,21 Control part 12,25 Transmission part 13,14,26 Transmission antenna 15,22 Reception part 16,23,24 Reception antenna
20 mobile device 30 noise source 221 antenna switching unit 222 demodulation unit 223 wake code signal determination unit

Claims (10)

A base station that transmits a request signal including at least a burst signal and a code signal following the burst signal to a transmission / reception device,
A transmission unit for transmitting the request signal to the transmission / reception device;
A receiving unit for receiving a response signal corresponding to the request signal from the transmission / reception device;
A controller that outputs the request signal to the transmitter and the response signal is input via the receiver;
The control unit is a base station that outputs a first request signal that is a request signal in which a transmission time of the burst signal is set longer than a transmission time of the code signal. The base station according to claim 1, wherein
The control unit is configured such that the transmission time of the burst signal is set to be longer than a timeout time that is a reception waiting time of the code signal in the transmission / reception apparatus, and the transmission time of the code signal is set to be shorter than the timeout time A base station that outputs a first request signal that is a request signal. The base station according to claim 2, wherein
The control unit outputs a second request signal that is a request signal set so that a transmission time of the burst signal is shorter than the timeout time, and a predetermined time after transmitting the second request signal A base station that outputs the first request signal when no response signal is detected. A transmission / reception apparatus that receives a request signal including at least a burst signal and a code signal following the burst signal from a base station,
A first receiving antenna;
A second receiving antenna;
A reception unit that receives the request signal via the first reception antenna and the second reception antenna, and the reception unit is received by the first reception antenna and the second reception antenna. An antenna switching unit that detects a signal level of the received signal and selects one of the signal levels that is high, and is received by either the first reception antenna or the second reception antenna that is selected by the antenna switching unit. A code signal determination unit that performs determination of the received signal,
The transmission time of the burst signal is set to be longer than a timeout time that is a reception waiting time of the code signal in the transmission / reception device,
When the second receiving antenna receives an unnecessary signal from the outside, the antenna switching unit selects the second receiving antenna, and the receiving unit shifts to a mode for receiving the burst signal,
Based on the interruption of the unnecessary signal from the outside, the receiving unit shifts to a mode for receiving the code signal,
After the elapse of the timeout time from the transition to the mode for receiving the code signal, the receiving unit transitions to the mode for receiving the burst signal,
When the first reception antenna receives the burst signal, the antenna switching unit selects the first reception antenna.
Transmitter / receiver. A base station that transmits a request signal including at least a burst signal and a code signal following the burst signal, and a transmission / reception device that receives the request signal and changes a reception mode,
The base station transmits a first request signal, which is a request signal set so that a transmission time of the burst signal is longer than a transmission time of the code signal,
The transmission / reception apparatus set to the mode for receiving the code signal shifts to the mode for receiving the burst signal based on the elapse of the timeout time.
Communications system. The communication system according to claim 5, wherein
In the base station, the transmission time of the burst signal is set to be longer than the timeout time which is the reception waiting time of the code signal in the transmission / reception apparatus, and the transmission time of the code signal is set to be shorter than the timeout time A communication system that outputs a first request signal that is a request signal. The communication system according to claim 6, wherein
The base station outputs a second request signal, which is a request signal set so that a transmission time of the burst signal is longer than the timeout time, and a predetermined time after transmitting the second request signal A communication system for outputting the first request signal when no response signal is detected. A communication method for performing communication between a base station and a transmission / reception device,
The base station is
A step of transmitting a first request signal, which is a request signal including a burst signal and a code signal following the burst signal, in which a transmission time of the burst signal is set longer than a transmission time of the code signal to the transmission / reception device Run
The transmitting / receiving device is
Shifting to a mode for receiving the burst signal based on an unnecessary signal from the outside;
Shifting to a mode for receiving the code signal based on the interruption of the unnecessary signal from the outside;
Receiving the first request signal;
Communication method to execute. The communication method according to claim 8, comprising:
In the base station, the transmission time of the burst signal is set to be longer than the timeout time which is the reception waiting time of the code signal in the transmission / reception apparatus, and the transmission time of the code signal is set to be shorter than the timeout time Executing a step of outputting a first request signal which is a request signal;
A communication method in which the transmission / reception apparatus executes a step of shifting to a mode of receiving the burst signal after elapse of the timeout time from the time of shifting to a mode of receiving the code signal. The communication method according to claim 9, comprising:
Before the base station transmits the first request signal to the transmission / reception device, the base station includes a code signal and a burst signal preceding the code signal, and the transmission time of the burst signal includes the code signal in the transmission / reception device. A communication method for further executing a step of transmitting a second request signal, which is a request signal set shorter than a timeout time which is a reception waiting time, to the transmission / reception apparatus.