JP5945850B2 - Wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system including a plurality of wireless stations.

  In recent years, the obligation to install fire alarms in houses has been legislated to reduce the number of victims of house fires, so multiple fire alarms can be linked using wireless signals from the viewpoint of workability in existing houses. A fire alarm system is desired. Such a fire alarm system has a function in which a plurality of fire alarms (wireless stations) installed in many places sense a fire and sound a warning sound. When any of the fire alarms senses a fire, the fire alarm sounds an alarm sound and transmits information (fire detection information) for notifying the fire detection to another fire alarm with a wireless signal. Thereby, not only the fire source fire alarm device but also a plurality of fire alarm devices are interlocked to sound an alarm sound all at once, so that the occurrence of a fire can be notified quickly and reliably. Such a fire alarm is driven using a battery as a power source in order to take advantage of the characteristic of transmitting fire detection information by radio signals. Moreover, since it is usually installed in a place where maintenance (battery replacement) is difficult, such as an indoor ceiling, it is desirable that it can be used without maintenance for a long period of time, such as several years.

  Here, in the fire alarm system as described above, when a fire is detected, a wireless signal is transmitted between a plurality of fire alarms. B) If radio signals are transmitted, the radio signals will collide. In order to avoid such a collision, for example, Patent Document 1 describes a fire alarm system in which a plurality of fire alarm devices transmit radio signals by a TDMA (Time Division Multiple Access) method.

JP 2009-251903 A Japanese Patent Laid-Open No. 7-235901

  By the way, in a wireless communication system such as the fire alarm system described in Patent Document 1, each wireless station operates normally by periodically transmitting a monitoring message from a specific wireless station to another wireless station. The operation to check whether or not is done. Here, in the space where the wireless communication system is constructed, fading occurs due to human movement and the received signal strength fluctuates, so that there is a possibility that the communication performance deteriorates and the operation check cannot be performed normally. This deterioration in communication performance due to fading is a problem that can occur not only when the operation is confirmed as described above, but also when wireless signals are transmitted and received between wireless stations.

  As means for avoiding this fading, there has been conventionally provided a means for receiving radio waves by a diversity method using a plurality of antennas, and is disclosed in Patent Document 2, for example. However, the conventional example described in Patent Document 2 always obtains a diversity effect by switching antennas. As described above, when the antenna is constantly switched, the time required for reception of the radio signal becomes long, and the power consumption necessary for switching the antenna also increases, resulting in a problem that the power consumption increases.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a wireless communication system capable of reducing deterioration in communication performance due to fluctuations in received signal strength without increasing power consumption. .

The wireless communication system of the present invention is a wireless communication system that includes a plurality of wireless stations, and transmits and receives wireless signals using a radio wave as a medium between the plurality of wireless stations, and each wireless station includes a plurality of antennas. A radio transmission / reception unit including a transmission unit that transmits a radio signal using any one of the antennas, and a reception unit that receives a radio signal using any one of the antennas; The transmission unit is activated when a predetermined event occurs, and an operation of transmitting a radio signal including a message corresponding to the event in a predetermined transmission period and pausing transmission of the radio signal in a predetermined pause period are alternately performed. Repetitive transmission control means for stopping the transmission means when the event has not occurred, timer means for repeatedly counting a constant intermittent reception interval, and A control unit having reception control means for stopping the reception means during counting of the intermittent reception interval by the timer means and starting the reception means each time counting of the intermittent reception interval by the timer means is completed; and a battery Power supply means for supplying operating power to the respective means using the power supply as a power source, and the control unit of at least one of the radio stations activates the transmission means to the other radio stations. The wireless signal is periodically transmitted to the control unit of each wireless station, and a search period is set in accordance with a transmission period of the periodically transmitted radio signal. switched and duration not receiving period and the radio signals received radio signal to start, the intermittent reception are alternately repeated at intervals shorter than the intermittent reception interval alternately each of the antennas The antenna having a high received signal strength in the search period is selected from the antennas, and the selected antenna is used as the antenna of the transmitting unit and the receiving unit at least until the next search period. It is characterized by that.

  In this radio communication system, it is preferable that the control unit of each radio station switches the antennas alternately for each period for receiving the radio signal in the search period.

  In this radio communication system, it is preferable that the control unit of each radio station switches the antennas alternately in succession within a period of receiving the radio signal in the search period.

  In this wireless communication system, each wireless station includes a fire alarm that detects the occurrence of a fire, a wireless station that has an air quality sensor that measures air quality, and a wireless station that has a human sensor that detects the presence of a person. At least one of them is preferable.

  The present invention has an effect that it is possible to reduce deterioration in communication performance due to fluctuations in received signal strength without increasing power consumption.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows embodiment of the radio | wireless communications system which concerns on this invention, (a) is a block diagram of a fire alarm device, (b) is the schematic of communication operation at the time of regular monitoring. It is a frame format of a radio signal in the above radio communication system. 4 is a time chart for explaining a communication operation when a fire is detected in the above wireless communication system. In the radio | wireless communications system same as the above, it is the schematic which shows the other communication operation at the time of regular monitoring.

  Hereinafter, embodiments of a wireless communication system according to the present invention will be described with reference to the drawings. As shown in FIG. 1A, the present embodiment includes a plurality (two in the figure) of fire alarms (wireless stations). In the following description, fire alarms are indicated as fire alarms TR1, TR2,..., TRn when indicated individually, and are indicated as fire alarms TR0 when indicated collectively. In the following description, the specific fire alarm device TR1 is referred to as “master station TR1,” and the other fire alarm devices TR2,.

  The fire alarm device TR0 includes a first antenna 10 and a second antenna 11, a wireless transmission / reception unit 2 (transmission unit, reception unit), an alarm unit 3, and an operation input reception unit 4. The fire alarm TR0 includes a fire detection unit 5, a control unit 6 (transmission control unit, reception control unit, timer unit), and a power source unit 7 (power supply) that supplies operating power to each unit using a battery such as a dry battery as a power source. Means).

  The radio transmission / reception unit 2 transmits / receives a radio signal using radio waves as a medium in accordance with “radio station of low power security system” defined in Article 6, Paragraph 4, Item 3 of the Radio Law Enforcement Regulations. And the radio | wireless transmission / reception part 2 receives the radio signal which another fire alarm device TR0 transmitted with either antenna 10 or 11 while transmitting the radio signal which used the radio wave as a medium from either antenna 10 and 11. FIG. The antennas 10 and 11 may be designed so as to protrude from the main body of the fire alarm device TR0. However, it is possible to produce antennas 10 and 11 that are built in the main body so as not to stand out.

  The alarm unit 3 includes a buzzer that sounds a buzzer sound and a speaker that sounds a voice message, and a fire alarm (hereinafter referred to as “alarm sound”) by a buzzer sound or a voice message (for example, “is a fire”). Is notified.

  The operation input receiving unit 4 includes one or more switches (for example, push button switches), and receives an operation input corresponding to each switch when the switch is operated and outputs an operation signal corresponding to the operation input. Output to the control unit 6. For example, the operation input accepting unit 4 accepts an operation input for stopping the sounding of the alarm sound by the alarm unit 3.

  The fire sensing unit 5 senses a fire by detecting smoke, heat, flame, and the like generated with the fire, for example. In addition, since the structure of the fire detection part 5 is conventionally well-known, detailed description is abbreviate | omitted here.

  The control unit 6 includes a memory unit 6A including a microcomputer or a rewritable nonvolatile semiconductor memory as a main component. The control part 6 implement | achieves the various functions mentioned later by running the program stored in memory (ROM or EEPROM etc.) which is not illustrated with a microcomputer. For example, when the fire detection unit 5 detects the occurrence of a fire, the control unit 6 drives the alarm unit 3 to sound an alarm sound, or for alarms stored in the memory (or the memory unit 6A) in advance. It has a function to notify a fire alarm by sounding a voice message. The control unit 6 also has a function of causing the wireless transmission / reception unit 2 to transmit a radio signal including a fire alarm message in order to notify the fire alarm also in other fire alarm devices TR0. In addition, the control unit 6 controls the alarm unit 3 to generate an alarm even when the control unit 6 receives a fire alarm message by receiving a radio signal transmitted from another fire alarm device TR0. It also has a function to sound.

  Each of the fire alarm devices TR1, TR2,... Is assigned a unique identification code and stored in the memory unit 6A, and the destination of the radio signal and the source fire alarm devices TR1, TR2,. Can be specified.

  Here, Article 49-17 “Radio Equipment for Radio Stations of Low Power Security System” of Radio Equipment Regulations of the Radio Law Enforcement Regulation stipulates that the transmission period is 3 seconds or less and the suspension period is 2 seconds or more. (See item 5 of the same article). The “transmission period” indicates a period during which the radio signal may be transmitted continuously, and the “pause period” is a period provided between the transmission period and the transmission period during which the radio signal should not be transmitted. Indicates. For this reason, the control unit 6 in the present embodiment transmits a radio signal during a transmission period that complies with the radio equipment rules, and stops transmission during a pause period and enables reception.

  The controller 6 repeatedly counts a predetermined intermittent reception interval (however, the intermittent reception interval is longer than the transmission period) by a timer (timer means) built in the microcomputer. Then, every time the counting is completed, the control unit 6 activates the wireless transmission / reception unit 2 to check whether or not a desired radio wave (a radio signal transmitted by another fire alarm device TR0) can be received. If the signal is not detected, the wireless transmission / reception unit 2 is immediately stopped to shift to a standby state. Thereby, the average power consumption is greatly reduced, and the battery life of the power supply unit 7 is made as long as possible. Here, the radio wave reception check is performed by the control unit 6 based on the RSSI signal which is a DC voltage signal output from the wireless transmission / reception unit 2 and is proportional to the magnitude of the received signal strength. I will omit it. The “RSSI signal” refers to a receiving signal strength (Receiving Signal Strength Indication) signal.

  Further, the control unit 6 of the master station TR1 causes the wireless transmission / reception unit 2 to be activated periodically (for example, every 24 hours) to transmit a wireless signal including a periodic monitoring message in order to perform periodic monitoring. Here, “periodic monitoring” means checking whether or not the slave stations TR2,... Are operating normally. After transmitting the radio signal including the regular monitoring message, the control unit 6 of the master station TR1 switches the radio transmission / reception unit 2 to the reception state and receives the radio signal transmitted from each of the slave stations TR2,.

  In the slave stations TR2,..., The control unit 6 monitors whether or not the fire detection unit 5 has failed and whether or not the power supply unit 7 has run out of battery at regular intervals (for example, every hour), and the monitoring result (failure) The presence / absence of the battery and the presence / absence of the battery dead) are stored in the memory unit 6A. Then, the control unit 6 of the slave stations TR2,... Receives a radio signal including a notification message for notifying the monitoring result stored in the memory unit 6A when receiving the regular monitoring message from the master station TR1. Reply to TR1.

  Here, if there is a slave station TR2,... That does not reply within a predetermined time after transmitting a radio signal including a periodic monitoring message, the control unit 6 of the master station TR1 drives the buzzer of the alarm unit 3. An alarm is sounded to notify the slave stations TR2,... That an abnormality has occurred. Here, “abnormal” indicates failure or battery exhaustion. Further, when the notification message returned from any of the slave stations TR2,... Notifies the monitoring result that there is an abnormality, the control unit 6 of the master station TR1 has an abnormality in the slave stations TR2,. Notify that it has occurred. When the control unit 6 of the fire alarm devices TR1, TR2,... Determines that an abnormality has occurred, a warning sound for notifying the occurrence of the abnormality immediately from the alarm unit 3 sounds from the buzzer or speaker of the alarm unit 3. It is supposed to let you.

  Further, the control unit 6 of the master station TR1 receives a fire alarm message from one of the slave stations TR2,... After the fire detection unit 5 detects a fire and transmits a fire alarm message to each of the slave stations TR2,. Thereafter, the wireless transmission unit 2 is caused to transmit a synchronization beacon at a constant cycle. The synchronous beacon is a signal that defines a time slot necessary for performing TDMA (time division multiple access) wireless communication (hereinafter referred to as “synchronous communication”) between a plurality of fire alarms TR0. One period (cycle) of the synchronization beacon is divided into a plurality of time slots, and one different time slot is assigned to each of the slave stations TR2,. Then, a message from the master station TR1 to the slave station TR2,... Is transmitted in a synchronous beacon, and a radio signal including a message from the slave station TR2,... To the master station TR1 is assigned to each slave station TR2,. Stored in the current time slot and transmitted.

  Therefore, it is possible to reliably avoid collision of radio signals transmitted from a plurality of fire alarm devices TR0 (master station TR1 and slave stations TR2,...). The time slot assignment for each fire alarm TR0 may be fixed, but the time slot assignment information may be notified to each slave station TR2,... By a synchronous beacon transmitted from the master station TR1.

  FIG. 2 shows a frame format of a radio signal transmitted and received by the fire alarm device TR0. In this frame format, one frame is composed of a synchronization bit (preamble: PA), a frame synchronization pattern (unique word: UW), a destination address (DA), a source address (SA), a message (M), and a CRC code. Yes. Here, if the identification code of each fire alarm device TR0 is set as the destination address (DA), only the fire alarm device TR0 with the identification code receives the radio signal and acquires the message. Also, if a special bit string that is not assigned to any fire alarm device TR0 is set as the destination address (DA) (for example, a bit string in which all bits are set to 1), all fire alarms are transmitted by multicasting radio signals. The message can be acquired by the device TR0. For example, a radio signal including a fire alarm message is multicast from the master station TR1 to all the slave stations TR2,.

  Next, the communication operation of this embodiment before and after the fire detection will be described with reference to FIG. For example, when the fire detection unit 5 detects a fire in the slave station TR2, the control unit 6 of the slave station TR2 sounds an alarm sound from the alarm unit 3, and before the count of the intermittent reception interval T1 by the timer is completed, the radio transmission / reception unit 2 is started. Then, the control unit 6 of the slave station TR2 sends a radio signal including a fire alarm message to all other fire alarm devices TR (the master station TR1 and other slave stations TR3,...) Within a transmission period including the count completion time. Send to. At this time, the control unit 6 of the transmission source child station TR2 continuously transmits the radio signal by the number of frames that can be transmitted within the transmission period, and the radio transmission / reception unit 2 during the pause period (reception period) after the transmission period. To the receiving state.

  As will be described later, when the fire alarm devices TR1, TR2,... Are ready to complete counting of the intermittent reception interval T1, a radio signal including a fire alarm message is received in one transmission period. be able to.

  Here, if the low-power radio is used, the wireless communication distance can be sufficiently covered as long as it is in an area of a normal house. Therefore, the fire station child station TR2 can connect other fire alarm devices TR (master station TR1 and It is usually possible to send a message to other slave stations TR3,. However, as described above, the master station TR1 periodically monitors the slave stations TR2 to TR4, and the normality of the communication path is confirmed between the master station TR1 and each of the slave stations TR2 to TR4. However, the communication path between the slave stations TR2 to TR4 has not been confirmed. For this reason, there is a possibility that a message does not reach a certain slave station due to the influence of an obstacle, for example.

  Therefore, the control unit 6 of the master station TR1 that has received the fire alarm message transmits a radio signal including the fire alarm message to the other slave stations TR3 and TR4 other than the source slave station TR2, and an intermittent reception interval T1 by the timer. It is transmitted in the transmission period including the time point of completion of counting. When the control unit 6 of the other slave stations TR3 and TR4 receives the fire alarm message transmitted from the slave station TR2 or the master station TR1, the alarm unit 3 immediately sounds an alarm sound. Further, the control units 6 of the other slave stations TR3 and TR4 send back a response message (ACK) for confirming reception of the fire alarm message from the radio transmission / reception unit 2 by a radio signal. In addition, when all the fire alarm devices TR0 notify a fire alarm (sound an alarm sound) when a fire is detected by at least one fire alarm device TR0 in this way, it is hereinafter referred to as “linked sounding”. .

  When the control unit 6 of the master station TR1 receives the response message (ACK) from all the other slave stations TR3 and TR4, the control unit 6 causes the radio transmission / reception unit 2 to transmit a synchronization beacon for defining a time slot at a constant period. In the present embodiment, the first time slot is assigned to the child station TR2, the second time slot is assigned to the child station TR3, and the third time slot is assigned to the child station TR4.

  Here, as described above, the master station TR1 periodically monitors the slave stations TR2 to TR4, and the normality of the communication path is confirmed between the master station TR1 and each of the slave stations TR2 to TR4. However, the communication path between the slave stations TR2 to TR4 has not been confirmed. Therefore, when a large number of slave stations TR2,... Are arranged, the number of communication paths between the slave stations TR2,. Exhaustion becomes intense. Therefore, in the present embodiment, as described above, the specific fire alarm device TR1 is a master station, the other fire alarm devices TR2,... Are slave stations, and the master station TR1 sends a fire alarm message to each slave station TR2,. Other messages (described later) are notified. As a result, even when there are slave stations that cannot establish a communication path with each other, the interlocking ringing can be reliably performed.

  Also, when all the fire alarms TR0 sound an alarm sound and the linked sounding is started, the control unit 6 of the master station TR1 includes the fire alarm message M1 (see FIG. 4) by including it in the synchronous beacon. It is repeatedly transmitted to all the slave stations TR2,. Then, the control unit 6 of each slave station TR2,... Checks the state of the alarm unit 3 every time the fire alarm message M1 transmitted from the master station TR1 is received, and if the alarm unit 3 is stopped, the alarm unit 3 causes the alarm to sound again.

  As described above, in the present embodiment, after fire alarms are started to be notified by all the fire alarm devices TR0, collision can be avoided by performing wireless communication by time division multiple access (TDMA). Further, in the present embodiment, a specific fire alarm (master station) TR1 periodically transmits a fire alarm message M1 in a synchronous beacon to all other fire alarms (slave stations) TR2,. Thus, it is possible to reliably notify the fire alarm. As a result, a plurality of fire alarm devices TR0 can be effectively linked while avoiding radio signal collision. Moreover, in this embodiment, since fire alarms are notified by all fire alarm devices TR0 in the event of a fire, the user has more opportunities to perceive the fire alarm (listen to the alarm sound) to improve safety. Can do.

  Incidentally, in the above communication operation, the timings at which the fire alarm devices TR1, TR2,... Start operation (the timer starts counting the intermittent reception interval T1) do not normally coincide. For this reason, the timing (refer to the downward arrow in FIG. 3) at which the control unit 6 of each fire alarm device TR1, TR2,... On the other hand, in this embodiment, as shown in FIG. 3, when the synchronization signal is received by the wireless transmission / reception unit 2 of each fire alarm device TR1, TR2,..., The control unit 6 sets the intermittent reception interval T1 by the timer. Stop counting. And the control part 6 restarts the count of the intermittent reception interval T1 by a timer when the fixed standby | waiting time T2 passes from the end time (t = t0) of a synchronizing signal.

  Therefore, after receiving the synchronization signal, the fire alarm devices TR1, TR2,... Have the same timing to complete the counting of the intermittent reception interval T1, so that the radio signal transmitted from one radio station is transmitted. All other radio stations can receive almost simultaneously. As a result, by performing intermittent reception, it is possible to shorten the delay time until another wireless station can receive a wireless signal transmitted from any wireless station, while reducing power consumption and extending battery life. .

  In the present embodiment, a radio signal including a periodic monitoring message transmitted from the master station TR1 to the slave stations TR2,... At a constant cycle is also used as a synchronization signal. For this reason, since periodic monitoring and synchronization of each fire alarm device TR1, TR2,... Can be performed collectively, power consumption is reduced compared to the case where a radio signal including a periodic monitoring message and a synchronization signal are individually transmitted. can do. In addition, this configuration has an advantage that the system configuration can be simplified because a dedicated transmitter (transmitting station) for transmitting the synchronization signal is not required.

  Here, as already described, fading may occur due to human movement or the like in a space where a wireless communication system is constructed, and communication performance may deteriorate due to fluctuations in received signal strength. In this case, there is a possibility that the above-described regular monitoring and synchronization cannot be performed normally. Therefore, in this embodiment, each radio station (fire alarm device TR0) is synchronized with the transmission period of a radio signal (a synchronization signal including a periodic monitoring message) periodically transmitted from a specific radio station (master station TR1). The search period is set. In the present embodiment, the antenna used in the wireless transmission / reception unit 2 is alternately switched between the first antenna 10 and the second antenna 11 during this search period to perform intermittent reception. Note that “intermittent reception” refers to alternately repeating a period in which a radio signal is received and a period in which no radio signal is received. In the present embodiment, an antenna having a high received signal strength is selected from the antennas 10 and 11 during the search period, and the antenna is used as an antenna of the wireless transmission / reception unit 2 thereafter.

  Hereinafter, a communication operation at the time of periodic monitoring according to the present embodiment will be described with reference to FIG. In the following, only the communication operation when the synchronization signal including the periodic monitoring message is transmitted from the master station TR1 to the slave station TR2 will be described, but the same communication operation is performed in the other slave stations TR3,. ing. First, in the figure, it is assumed that the slave station TR2 uses the first antenna 10 as the antenna of the radio transceiver unit 2 before the synchronization signal including the regular monitoring message is transmitted from the master station TR1. Further, the control unit 6 of the slave station TR2 sets a search period in accordance with the transmission period of the synchronization signal. For example, if the interval at which the synchronization signal is transmitted is 24 hours, the control of the slave station TR2 starts when a certain waiting time T2 has elapsed from the end of the synchronization signal when the previous synchronization signal is received. The unit 6 measures 24 hours, and starts the search period when the timing is completed.

  In the search period, the control unit 6 of the slave station TR2 counts an interval T3 shorter than the normal intermittent reception interval T1 with a timer, and activates the radio transmission / reception unit 2 every time the count is completed. Here, the control unit 6 of the slave station TR2 alternately switches the first antenna 10 and the second antenna 11 every time the radio transmission / reception unit 2 is activated. That is, in the search period, the antenna used by the wireless transmission / reception unit 2 is switched for each period during which a wireless signal is received. Further, the control unit 6 of the slave station TR2 compares the received signal strengths of the synchronization signals received by the antennas 10 and 11 during the search period. When the search period elapses, the control unit 6 of the slave station TR2 selects an antenna having a high received signal strength in the search period from the antennas 10 and 11, and uses the antenna in the radio transmission / reception unit 2. In the example shown in FIG. 1B, since the second antenna 11 has a higher received signal strength than the first antenna 10 during the search period, the slave station TR2 serves as the antenna of the radio transmission / reception unit 2 after the search period elapses. Two antennas 11 are used. As a result, the radio transmission / reception unit 2 of the slave station TR2 can select and use an antenna having a high received signal strength for each search period.

  As described above, in the present embodiment, a so-called diversity method is employed in which an antenna having a high received signal strength selected in the search period is used as the antenna of the wireless transmission / reception unit 2. Degradation of performance can be reduced. Further, in the present embodiment, the antennas 10 and 11 are switched by adopting the diversity method only during the search period. For this reason, the power consumption required to switch the antennas 10 and 11 can be kept to a minimum, and an increase in power consumption can be suppressed as compared with the case of switching the antennas 10 and 11 constantly.

  As shown in FIG. 4, the control unit 6 of the slave station TR2 may switch the first antenna 10 and the second antenna 11 continuously within the period of receiving the radio signal. Even in this case, the same effects as described above can be obtained.

  In the present embodiment, the antenna used for the wireless transmission / reception unit 2 is selected from either the first antenna 10 or the second antenna 11. However, the antenna to be used is selected from a larger number of antennas. May be. In this case, although the power consumption increases as compared with the case of selecting from two antennas, it is possible to further reduce the deterioration of the communication performance due to the fluctuation of the received signal strength.

  By the way, in the present embodiment, the periodic monitoring message is included in the synchronization signal periodically transmitted from the master station TR1, but the synchronization signal and the periodic monitoring message may be transmitted separately. In this case, the antennas 10 and 11 may be switched in the reception period corresponding to the transmission period of at least one of the synchronization signal and the radio signal including the periodic monitoring message. As a result, similarly to the above, it is possible to achieve an effect of reducing deterioration in communication performance due to fluctuations in received signal strength without increasing power consumption.

  In this case, the synchronization signal may be transmitted from a dedicated transmission station (not shown) or may be transmitted from the fire alarm device TR0. When the synchronization signal is transmitted from the dedicated transmission station, there is an advantage that battery consumption in the fire alarm device TR0 can be reduced as compared with the case where the synchronization signal is transmitted from the fire alarm device TR0.

  Furthermore, when the synchronization signal is transmitted from the fire alarm device TR0, it is desirable that all the fire alarm devices TR0 transmit the synchronization signal in order every certain period (for example, 24 hours). For example, the identification code of the next fire alarm TR0 is included in the last synchronization signal transmitted from the current fire alarm TR0, and the fire alarm TR0 corresponding to the identification code transmits the next synchronization signal. You just have to do it. With this configuration, it is possible to avoid a situation in which only the master station TR1 transmits the synchronization signal, so that the battery of the master station TR1 is consumed earlier than the batteries of the slave stations TR2,.

  In addition, the radio station of this embodiment is not limited to the above-mentioned fire alarm device TR0. For example, the wireless communication system of the present embodiment may be constructed using a wireless station other than the fire alarm TR0.

  For example, the wireless communication system of the present embodiment may be constructed using a wireless station having an air quality sensor that measures a so-called air quality such as humidity in the air. An example of an air quality sensor is a gas sensor. Gas sensors measure fuel gas such as city gas and LP gas, COx gas components that measure the environment, such as carbon dioxide and carbon monoxide, or other gas components and dirt such as dust floating in the air. To do. As a radio station having this gas sensor, there is a gas alarm device that notifies the occurrence of gas leakage or incomplete combustion with an alarm sound.

  Moreover, you may construct | assemble the radio | wireless communications system of this embodiment using the radio station which has a human sensor which detects presence of a person. The human sensor is a method of detecting the presence of a person by detecting infrared rays emitted from the human body, or a method of detecting the presence of a person by performing image processing analysis on an image obtained by imaging a target area. It is possible to adopt. Or you may employ | adopt as a human sensor combining the said both systems.

  Further, a wireless communication system may be constructed by mixing a wireless station having the air quality sensor or a wireless station having a human sensor with the wireless fire alarm TR0 described above. In this case, it is possible to construct a wireless communication system that serves not only for fire detection but also for the purpose of human body detection and ventilation warning.

DESCRIPTION OF SYMBOLS 10 1st antenna 11 2nd antenna 2 Wireless transmission / reception part (transmitting means, receiving means)
6 Control unit (transmission control means, reception control means, timer means)
7 Power supply (power supply means)
TR1, TR2 Fire alarm (radio station)

Claims (4)

A wireless communication system comprising a plurality of wireless stations and transmitting and receiving wireless signals using radio waves as a medium between the plurality of wireless stations,
Each of the radio stations receives a radio signal using a plurality of antennas, a transmission unit that transmits a radio signal using any one of the antennas, and any one of the antennas. A wireless transmission / reception unit having a reception unit configured to activate the transmission unit when a predetermined event occurs, transmit a radio signal including a message corresponding to the event during a predetermined transmission period, and perform radio transmission during a predetermined pause period The operation of pausing the transmission of the signal is alternately repeated, and the transmission means for stopping the transmission means when the event has not occurred, the timer means for repeatedly counting a constant intermittent reception interval, and the intermittent by the timer means While the reception interval is being counted, the reception unit is stopped, and every time the intermittent reception interval is counted by the timer unit, And a control unit having a receiving control means for activating the reception means, a feeding means for feeding the operating power to each unit of the battery as the power source,
The control unit of at least one of the radio stations activates the transmission unit to periodically transmit a radio signal to the other radio stations,
The control unit of each radio station sets a search period in accordance with a transmission period of the periodically transmitted radio signal, and in the search period, a period in which the reception unit is activated to receive a radio signal; Intermittent reception that alternately repeats a period in which no radio signal is received at an interval shorter than the intermittent reception interval while alternately switching the antennas, and among the antennas, the received signal strength is high in the search period A radio communication system, wherein an antenna is selected, and the selected antenna is used as the antenna of the transmitting unit and the receiving unit at least until the next search period.   2. The wireless communication system according to claim 1, wherein the control unit of each of the wireless stations alternately switches the antennas for each period of receiving the wireless signal in the search period.   2. The wireless communication system according to claim 1, wherein the control unit of each wireless station switches the antennas alternately in succession during a period of receiving the wireless signal in the search period. Each wireless station is at least one of a fire alarm that detects the occurrence of a fire, a wireless station that has an air quality sensor that measures air quality, and a wireless station that has a human sensor that detects the presence of a person. The wireless communication system according to claim 1, wherein the wireless communication system is provided.

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