JP5979540B2 - 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 radio communication system such as the fire alarm system described in Patent Document 1, radio wave check is performed to test the normality of communication paths between radio stations when a radio station is constructed or when the installation location is moved. ing. Here, in a space where a wireless communication system is constructed, fading may occur due to human movement or the like, and communication performance may deteriorate due to fluctuations in received signal strength. In this case, even if the communication path between the wireless stations is normal at the time of radio wave check, there is a possibility that communication cannot be performed between the wireless stations during actual operation.

  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 wireless transmission / reception unit that transmits / receives a wireless signal using any one of the antennas, and a wireless signal including a message corresponding to the event during a predetermined transmission period when a predetermined event occurs In addition, the control for alternately repeating the operation of stopping the transmission of the radio signal during a predetermined pause period, the intermittent reception interval is repeatedly counted, and the radio transmission / reception unit is stopped during the counting of the intermittent reception interval, and the intermittent reception is performed. A control unit that performs control to activate the wireless transmission / reception unit each time the interval count is completed, and one or more switches, and the switch is operated An operation input receiving unit that receives an operation input corresponding to each switch and outputs an operation signal corresponding to the operation input to the control unit, and a battery power supply unit that supplies operating power to each unit using a battery as a power source The operation input receiving unit includes a test switch for starting a radio wave check for testing the normality of a communication path between the radio stations, and one radio station among the radio stations. Upon receiving an operation input of the test switch, the control unit activates the wireless transmission / reception unit to transmit a test signal that prompts another wireless station to reply, and the control unit of the other wireless station is, in the transmission period of the test signal, upon receiving the test signal, said antenna being used in a wireless transceiver is switched to another antenna, the reception result of the test signal at each antenna Based selects one of the antennas, characterized by using said selected antenna by the wireless transmitting and receiving unit.

  In this radio communication system, it is preferable that the control unit of the other radio station compares the received signal strengths of the test signals in the antennas and selects the antenna having the higher received signal strength.

  In this radio communication system, the control unit of the other radio station alternately switches the antenna used in the radio transmission / reception unit a plurality of times during the transmission period of the test signal, and receives a plurality of the test signals obtained. It is preferable that a probability distribution of received signal strength is obtained from the signal strength for each antenna, and an antenna having high communication performance is selected based on the probability distribution.

  In this wireless communication system, the operation input receiving unit includes a changeover switch, and the control unit switches from an antenna used in the wireless transmission / reception unit to another antenna when receiving an operation input of the changeover switch. It is preferable.

  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.

  In the present invention, the antenna used in the wireless transmission / reception unit is switched at the time of radio wave check to receive the test signal, and the antenna to be used later in the wireless transmission / reception unit is selected based on the reception result. Therefore, the present invention can reduce deterioration in communication performance due to fluctuations in received signal strength without increasing power consumption.

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 a radio wave check. 4 is a time chart for explaining a communication operation when a fire is detected in the above wireless communication system. (A) is the schematic of the other communication operation at the time of the radio wave check in a radio | wireless communications system same as the above, (b) is a figure which shows the probability distribution of the received signal strength in either slave station of a radio | wireless communications system same as the above.

  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, an alarm unit 3, and an operation input receiving unit 4. The fire alarm device TR0 includes a fire detection unit 5, a control unit 6, and a battery power supply unit 7 that supplies operating power to each unit using a battery such as a dry battery as a power source.

  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. In the present embodiment, when the fire alarm device TR0 is installed or when the installation location of the fire alarm device TR0 is moved, a radio wave check is performed to test the normality of the communication path between the fire alarm devices TR0. Therefore, in the present embodiment, a test switch for starting the radio wave check is provided in the operation input receiving unit 4.

  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 control unit 6 repeatedly counts a predetermined intermittent reception interval (however, the intermittent reception interval is longer than the transmission period) by a timer 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. As a result, the average power consumption is greatly reduced, and the battery life of the battery 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 an RSSI signal that is a DC voltage signal output from the wireless transmission / reception unit 2 and proportional to the magnitude of the received signal strength. Details of the radio wave reception check are well known in the art and will be omitted. The “RSSI signal” refers to a receiving signal strength (Receiving Signal Strength Indication) signal.

  Further, the control unit 6 of the master station TR1 performs a radio wave check for confirming the normality of the communication path between the slave stations TR2,. The radio wave check will be briefly described below. When the control unit 6 of the master station TR1 receives an operation input of the test switch of the operation input receiving unit 4 of the master station TR1, the control unit 6 activates the radio transmission / reception unit 2 and includes a radio signal including a test message (hereinafter, “test signal”). Are transmitted to each of the slave stations TR2,. This test message urges each of the slave stations TR2,... To return that the signal has been received. After transmitting the test signal, the control unit 6 of the master station TR1 switches the radio transmission / reception unit 2 to the reception state and stands by so as to receive a reply signal from each of the slave stations TR2,.

  When receiving the test signal from the master station TR1, the control unit 6 of each slave station TR2 activates the wireless transmission / reception unit 2 to transmit a response signal to the test signal toward the master station TR1. If there are slave stations TR2,... That do not reply within a predetermined time after transmitting the test signal, the control unit 6 of the master station TR1 drives the buzzer of the alarm unit 3 to sound a notification sound, etc. , Informs that there is an abnormality in the communication path between the slave stations TR2,.

  Here, the control unit 6 of the master station TR1 may be configured to transmit a test signal to each of the slave stations TR2,. That is, if there is a slave station TR2,... That does not reply within a predetermined time after transmitting the test signal, the control unit 6 of the master station TR1 activates the wireless transmission / reception unit 2 to the slave stations TR2,. The test signal is transmitted again. Then, when the test signal is transmitted a predetermined number of times and there is still no reply from the slave stations TR2,..., The control unit 6 of the master station TR1 drives the buzzer of the alarm unit 3 to sound a notification sound, etc. Then, it is notified that there is an abnormality in the communication path between the slave stations TR2,.

  When the test switch of the operation input receiving unit 4 is operated at any of the slave stations TR2,..., The slave stations TR2,... Prompt the master station TR1 to perform a radio wave check. That is, the control unit 6 of the slave stations TR2,... That has operated the operation switch activates the radio transmission / reception unit 2 to transmit a radio signal including a message prompting the start of the radio wave check to the master station TR1. When receiving the radio signal, the control unit 6 of the master station TR1 starts the radio wave check described above.

  Further, the control unit 6 of the master station TR1 receives a fire alarm message 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,. A message from the master station TR1 to the slave stations TR2,. Further, a radio signal including a message from the slave station TR2,... To the master station TR1 is stored in a time slot assigned to each slave station TR2,.

  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.

  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. In addition, the control unit 6 of the slave station TR2 activates the wireless transmission / reception unit 2 before the completion of the intermittent reception interval T1 by the timer. Then, the control unit 6 of the slave station TR2 sends a radio signal including a fire alarm message to all other fire alarms (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.

  Here, if low-power radio is used, the radio communication distance can be sufficiently covered as long as it is within an area of a normal house. Therefore, the fire station child station TR2 can connect other fire alarms (master station TR1 and other stations). It is usually possible to send a message to the slave stations TR3,. However, even if the normality of the communication path is confirmed between the master station TR1 and each of the slave stations TR2 to TR4, the communication path between the slave stations TR2 to TR4 may not be 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, when a large number of slave stations TR2,... Are arranged, the number of communication paths between the slave stations TR2,. Battery consumption 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 interlocking sounding is started, the control unit 6 of the master station TR1 includes the fire alarm message in a certain period to all the slave stations. Repeatedly transmit to TR2,. Then, the control unit 6 of each slave station TR2,... Checks the state of the alarm unit 3 every time it receives a fire alarm message transmitted from the master station TR1, and if the alarm unit 3 is stopped, the alarm unit 3 is stopped. Sound the alarm 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). Furthermore, in this embodiment, a specific fire alarm (master station) TR1 periodically transmits a fire alarm message in a synchronous beacon to all other fire alarms (slave stations) TR2,. Can 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. 2) at which the control unit 6 of each fire alarm device TR1, TR2,... On the other hand, in this embodiment, as shown in FIG. 2, 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, the master station TR1 transmits a synchronization signal to the slave stations TR2,... At a constant cycle (for example, 24 hours). This configuration has the advantage that the system configuration can be simplified without the need for a dedicated transmitter (transmitting station) for transmitting the synchronization signal. The synchronization signal may be transmitted from a dedicated transmission station (not shown). 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,.

  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, when actually operating, there is a possibility that communication (for example, the above-mentioned interlocking ringing) cannot be normally performed between the wireless stations.

  Therefore, in the present embodiment, the control unit 6 of each of the slave stations TR2,... Switches the antenna used by the wireless transmission / reception unit 2 to another antenna when receiving the test signal during the transmission period of the test signal at the time of radio wave check. Then, the control unit 6 of each of the slave stations TR2,... Determines the antenna to be used thereafter by the radio transmission / reception unit 2 based on the reception result of the test signal at each antenna. In the present embodiment, the control unit 6 of each of the slave stations TR2,... Selects an antenna having a high received signal strength among the antennas, and uses the antenna as an antenna of the radio transmission / reception unit 2 thereafter.

  Hereinafter, the communication operation at the time of radio wave check according to the present embodiment will be described with reference to FIG. In the following, only the communication operation when a test signal is transmitted from the master station TR1 to the slave station TR2 will be described, but the same communication operation is also performed in the other slave stations TR3,. First, in the figure, it is assumed that the slave station TR2 is using the first antenna 10 as the antenna of the wireless transmission / reception unit 2 before the test number is transmitted from the master station TR1.

  When the test signal is received by the first antenna 10 during the transmission period of the test signal, the control unit 6 of the slave station TR2 switches the antenna used by the radio transmission / reception unit 2 from the first antenna 10 to the second antenna 11. Thereafter, the slave station TR2 also receives the test signal with the second antenna 11. The control unit 6 of the slave station TR2 compares the received signal strengths of the test signals received by the antennas 10 and 11. Then, the control unit 6 of the slave station TR2 selects an antenna having a high received signal strength from the antennas 10 and 11, and uses the antenna in the radio transmission / reception unit 2 thereafter.

  In the example shown in FIG. 1B, the second antenna 11 has a higher received signal strength than the first antenna 10. For this reason, the slave station TR2 uses the second antenna 11 as the antenna of the radio transmission / reception unit 2 after the elapse of the test signal transmission period. 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, that is, a high communication performance every time radio wave check is performed.

  As described above, the present embodiment employs a so-called diversity method in which an antenna having a high received signal strength selected at the time of radio wave check is used as the antenna of the wireless transmission / reception unit 2. For this reason, in this embodiment, it is possible to select and use an antenna with high communication performance for each radio wave check, and therefore it is possible to reduce deterioration in communication performance due to fluctuations in received signal strength. Further, in the present embodiment, the antennas 10 and 11 are switched by adopting the diversity method only at the time of radio wave check. 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.

  By the way, as shown to Fig.3 (a), you may comprise so that the antenna used by the radio | wireless transmission / reception part 2 may be switched alternately several times in the transmission period of a test signal. Hereinafter, a method for selecting an antenna to be used in the wireless transmission / reception unit 2 in this configuration will be described. First, as shown in FIG. 3A, when the control unit 6 of the slave station TR2 receives the test signal, the control unit 6 alternately switches the antenna used in the radio transmission / reception unit 2 a plurality of times. Thereby, the control unit 6 of the slave station TR2 obtains data of a plurality of received signal strengths for the antennas 10 and 11, respectively.

  The control unit 6 of the slave station TR2 obtains an average value and variance from the obtained received signal strength data, and from this average value and variance, a probability distribution having a probability density function having the received signal strength as a random variable is obtained. Obtained for each of the antennas 10 and 11 (see FIG. 3B). Here, the probability distribution of the received signal strength is obtained using the average value of the received signal strength of each of the slave stations TR2,. Further, the control unit 6 of the child station TR2 assumes that it is difficult to receive a radio signal when the received signal strength is equal to or lower than a predetermined value, and the received signal strength is equal to or lower than the predetermined value based on the average value and variance of the probability distribution. Is calculated for each of the antennas 10 and 11. Then, the control unit 6 of the child station TR2 selects an antenna having a smaller probability x obtained by the calculation, and uses the antenna in the radio transmission / reception unit 2 thereafter.

  In the example illustrated in FIG. 3B, the probability x of the second antenna 11 is smaller than that of the first antenna 10. For this reason, the slave station TR2 uses the second antenna 11 as the antenna of the radio transmission / reception unit 2 after the elapse of the test signal transmission period. As a result, the radio transmission / reception unit 2 of the slave station TR2 can select and use an antenna that easily receives a radio signal each time radio wave check is performed, that is, has high communication performance.

  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.

  In the present embodiment, the operation input receiving unit 4 may be provided with a changeover switch for switching the antenna currently used in the wireless transmission / reception unit 2 to another antenna. For example, if the changeover switch is operated while the wireless transmission / reception unit 2 is using the first antenna 10, the control unit 6 of the fire alarm device TR 0 that has operated the changeover switch sets the antenna used by the wireless transmission / reception unit 2 to the first. The antenna 10 is switched to the second antenna 11. In this configuration, for example, when the communication performance of the first antenna 10 deteriorates, the antenna used in the wireless transmission / reception unit 2 can be switched to another antenna without performing a radio wave check.

  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 6 Control part 7 Battery power supply part TR1, TR2 Fire alarm (radio station)

Claims (5)

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 wireless station includes a plurality of antennas, a wireless transmission / reception unit that transmits / receives a wireless signal using any one of the antennas, and a predetermined transmission period when a predetermined event occurs. Control that alternately transmits a radio signal including a corresponding message and pauses transmission of a radio signal during a predetermined pause period, and repeatedly counts a certain intermittent reception interval and counts the intermittent reception interval while counting A control unit that performs control to stop the wireless transmission / reception unit and activate the wireless transmission / reception unit each time counting of the intermittent reception interval is completed; and one or more switches, and the switch is operated. An operation input receiving unit that receives an operation input corresponding to each switch and outputs an operation signal corresponding to the operation input to the control unit; And a battery power supply unit for supplying a operating power to each unit as,
The operation input receiving unit has a test switch for starting a radio wave check for testing the normality of a communication path between the wireless stations,
When the control unit of one of the radio stations receives an operation input of the test switch, the control unit activates the radio transmission / reception unit to transmit a test signal that prompts another radio station to reply. ,
When the control unit of the other radio station receives the test signal during the transmission period of the test signal , the control unit switches the antenna used in the radio transmission / reception unit to another antenna, and performs the test on each antenna. One of the antennas is selected based on a signal reception result, and the selected antenna is used in the wireless transmission / reception unit.   The radio communication system according to claim 1, wherein the control unit of the other radio station compares the received signal strengths of the test signals in the antennas and selects the antenna having the higher received signal strength.   The control unit of the other radio station alternately switches the antenna used in the radio transmission / reception unit a plurality of times during the transmission period of the test signal, and receives the received signal strength from the received signal strength of the plurality of obtained test signals. The wireless communication system according to claim 1, wherein a probability distribution is calculated for each antenna, and an antenna having high communication performance is selected based on the probability distribution.   The operation input receiving unit includes a changeover switch, and the control unit switches from an antenna used in the wireless transmission / reception unit to another antenna when receiving an operation input of the changeover switch. Item 4. The wireless communication system according to any one of Items 1 to 3. 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 radio communication system according to claim 1, wherein the radio communication system is provided.

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