JP2011205591A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system in which the service life of a battery is prolonged while preventing synchronization loss with a synchronizing signal.SOLUTION: A conventional system sets the period of synchronizing signals across the board at eight hours on the basis of the specs of an oscillator (tuning fork crystal resonator) to be used for an oscillating device 6, and thus, the synchronizing signals are transmitted at a period shorter than necessity to shorten the service life of batteries in a master device TR1 and a slave device TRi. In order to solve the problem, in this system, a control part 1 of a master device TR1 controls the period of synchronizing signals on the basis of a value of an actual frequency deviation of an oscillator used for the oscillating device 6, and thus, power consumption due to transmission of the synchronizing signals and detection of time deviation ΔT is suppressed while preventing synchronization loss of the synchronizing signals to prolong the service life of batteries.

Description

  The present invention relates to a radio communication system including a plurality of radio stations, and more particularly to a radio communication system in which each radio station operates using a battery as a power source.

  For radio stations used in Japan, the characteristics of radio waves used (RF characteristics) such as occupied frequency bandwidth and adjacent channel leakage power must satisfy the provisions of the Radio Law. In the Radio Law, different standards (communication standards) are defined for each purpose of use. For example, “low-power radio stations” defined as one of the radio stations that do not require a license in the proviso to Article 4 of the Radio Law include “wireless stations for cordless telephones”, “specified low-power radio stations”, “low-power radio stations” There are “security system”, “low-power data communication system radio station”, etc., and the standards for the radio equipment of each radio station are stipulated by the equipment regulations of the law.

  Conventionally, there is one described in Patent Document 1 as a wireless communication system including a plurality of wireless stations that operate using a battery as a power source. In the conventional system described in Patent Document 1, each radio station intermittently activates a reception circuit to check whether or not a desired radio wave (a radio signal transmitted by another radio station) can be received. If radio waves are not captured, the average power consumption is greatly reduced by immediately stopping the receiving circuit and shifting to a standby state.

  However, when the intermittent reception operation is performed as described above, the timing of receiving the radio signal that should be received is delayed by the intermittent reception interval of the reception circuit. Therefore, the intermittent reception interval cannot be simply extended for the purpose of reducing power consumption.

  Therefore, the applicant of the present invention is that each wireless station that receives a synchronization signal transmitted in a period of several hours to several tens of hours counts the intermittent reception interval in synchronization with the synchronization signal, so that any wireless station transmits There has already been proposed a radio communication system in which the delay time until another radio station can receive the radio signal is shortened.

  By the way, the intermittent reception interval in the conventional system is counted by counting a clock signal input from an oscillator externally attached to the microcontroller by a microcontroller included in the wireless station. For such an oscillator, a tuning fork type crystal resonator (frequency is about 32 kilohertz) having a frequency deviation of about several tens of ppm is usually used. Therefore, if the intermittent reception interval is counted by the clock signal with such low accuracy, it is difficult for each wireless station to maintain synchronization of the intermittent reception interval over a long period of time.

  On the other hand, the present applicant detects the time lag between the reception timing of the synchronization signal and the intermittent reception interval counted by the timer and executes a process for correcting the detected time lag at each radio station, thereby generating an oscillation circuit. A wireless communication system has been proposed in which loss of synchronization due to time deviation due to frequency deviation is prevented.

JP 2008-176515 A

  By the way, the interval (cycle) at which the synchronization signal is transmitted is determined based on the frequency deviation of the resonator (tuning fork type crystal resonator) used in the oscillator. For example, if the maximum value of the frequency deviation is about ± 50 ppm and the signal width of the synchronization signal is 2.8 seconds, the synchronization may be lost in about 7.8 hours. Therefore, in consideration of individual differences of the oscillators, it is necessary to set the period of the synchronization signal assuming that the frequency deviation becomes the maximum value. For example, in the above example, the period of the synchronization signal must be set to a time shorter than about 7.8 hours.

  However, since the percentage of the oscillators that actually have the maximum frequency deviation is considered to be very low, the synchronization signal is normally transmitted at a frequency that is higher than necessary. There was a problem that the life would be shortened.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wireless communication system capable of extending battery life while preventing loss of synchronization with respect to a synchronization signal.

  In order to solve the above-mentioned problem, the first invention is a wireless communication system comprising a plurality of wireless stations, and transmitting and receiving a wireless signal using a radio wave as a medium between the plurality of wireless stations, A transmission / reception unit for transmitting / receiving a radio signal; a timer unit for repeatedly counting a certain intermittent reception interval; and a transmission / reception unit that is activated when a predetermined event occurs, and includes a message corresponding to the event during a predetermined transmission period An operation of alternately transmitting a radio signal and pausing transmission of a radio signal during a predetermined pause period is repeated, and when the event does not occur, the transmission / reception unit is stopped, and further, the intermittent reception interval of the timer unit is set. The transmission / reception means is stopped during the counting, and the transmission / reception is performed each time the intermittent reception interval is counted by the timer means. A transmission / reception control means for activating a stage; and a power supply means for supplying an operating power for each means using a battery as a power supply. The transmission / reception control means stops counting the intermittent reception interval by the timer means when the synchronization signal is received by the transmission / reception means, and a certain waiting time from the end of the synchronization signal. When the event occurs, the transmission / reception is performed in the transmission period that overlaps the time when the counting of the intermittent reception interval by the timer unit is completed. Wireless signal is transmitted from the means, and when the synchronization signal is received by the transmission / reception means, A time lag detecting means for detecting a time lag between the transmission timing and the intermittent reception interval counted by the timer means, and correcting the counting operation of the timer means so as to reduce the time lag detected by the time lag detecting means. A correction means that performs the transmission / reception control for each of the plurality of wireless stations, wherein the transmission / reception control means of the specific wireless station periodically synchronizes with the transmission / reception means at a period sufficiently longer than the intermittent reception interval. The transmission / reception control unit of the other radio station excluding the specific radio station transmits a radio signal including information on a time lag of the intermittent reception interval by the timer unit from the transmission / reception unit. And the transmission / reception control means of the specific radio station is based on the information on the time difference included in the radio signal transmitted from the other radio station. And adjusting the period of the synchronizing signal.

  According to a second aspect, in the first aspect, the transmission / reception control unit of the other radio station uses the detection result of the time shift detection unit as information related to the time shift.

  In a third aspect based on the second aspect, the time lag detection means ranks the magnitude of the time lag, and the transmission / reception control means of the other radio station determines the rank as information related to the time lag. It is characterized by doing.

  In a fourth aspect based on the first aspect, the other radio station includes storage means for storing information on a frequency deviation of a clock signal oscillated by the oscillator, and the transmission / reception control means of the other radio station includes The frequency deviation information stored in the storage means is information relating to the time shift.

  According to a fifth invention, in the fourth invention, the storage means stores a frequency deviation rank corresponding to the magnitude of the frequency deviation as information of the frequency deviation.

  According to a sixth invention, in the fourth or fifth invention, the transmission / reception control unit of the other radio station transmits a radio signal including information on the time lag from the transmission / reception unit before starting the operation of the system. It is characterized by transmitting to a radio station.

  According to a seventh aspect based on the sixth aspect, the specific radio station comprises storage means for storing a frequency deviation rank corresponding to the magnitude of the frequency deviation of the clock signal oscillated by the oscillator, and the specific radio station The transmission / reception control unit of a station transmits a radio signal using only the radio station having the same frequency deviation rank as the own frequency deviation rank stored in the storage unit as the other radio station.

  According to the present invention, it is possible to extend battery life while preventing loss of synchronization with respect to a synchronization signal.

It is a block diagram of the fire alarm device (parent device and child device) in Embodiment 1 of the present invention. It is a frame format of the radio signal in the same as above. It is a flowchart for demonstrating the operation | movement which changes to a fire interlocking state from a standby state same as the above. It is a time chart for demonstrating the operation | movement which changes to the interlocking stop state from the interlocking ringing state same as the above. It is a time chart for demonstrating the operation | movement which changes to the interlocking stop state from the interlocking ringing state same as the above. It is a time chart for demonstrating the operation | movement which changes to a standby state from a fire interlocking state same as the above. It is a time chart for demonstrating the operation | movement in a fire interlocking state same as the above. It is operation | movement explanatory drawing of the time shift detection means in the same as the above. It is operation | movement explanatory drawing of the time shift detection means in the same as the above. It is operation | movement explanatory drawing of the time shift detection means in the same as the above. It is a sequence diagram for demonstrating the operation | movement at the time of the registration operation | work in Embodiment 2 of this invention.

  The technical idea of the present invention will be described below in a radio communication system (fire alarm system) in which a fire alarm device that emits a radio signal including a fire detection message using a radio wave as a medium while detecting a fire is used as a radio station. An embodiment to which is applied will be described.

(Embodiment 1)
FIG. 1 is a system configuration diagram of the present embodiment, and a fire alarm system is configured by a plurality (only two in the drawing) of fire alarms TR. In the following description, when the fire alarms TR are individually indicated, they are indicated as fire alarms TR1, TR2,..., TRn, and when collectively indicated, they are indicated as fire alarms TR.

  The fire alarm TR includes a control unit 1 that is a transmission / reception control unit, a wireless transmission / reception unit 2 and an antenna 3 that are transmission / reception units, an oscillator 6 that oscillates a clock signal with a fixed period, a battery power supply unit 8 that is a power supply unit, and a fire detection unit. 4, the alarm part 5, the operation input reception part 7, etc. are provided.

  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. For example, it is composed of a commercially available LSI for low-power wireless communication.

  The fire sensing unit 4 senses a fire by detecting smoke, heat, flame, etc. generated by the fire, for example. However, the detailed configuration of such a fire detection unit 4 is well known in the art and will not be described in detail.

  The alarm unit 5 notifies (fires from a speaker) a fire alarm (hereinafter referred to as “alarm sound”) by sound (such as a buzzer sound or a voice message). The operation input receiving unit 7 includes one or more switches (for example, push button switches), and outputs an operation input (operation signal) corresponding to each switch to the control unit 1 when the switch is operated. The battery power supply unit 7 supplies operation power to each unit using a battery such as a dry battery as a power source.

  The control unit 1 includes a memory unit 1a including a microcontroller (hereinafter abbreviated as a microcomputer), a rewritable nonvolatile semiconductor memory, and the like as main components. In the control unit 1, when the fire detection unit 4 detects a fire, the alarm unit 5 sounds an alarm sound and transmits a radio signal including a fire alarm message for notifying other fire alarms TR of the fire alarm. The wireless transmission / reception unit 2 transmits the data. The control unit 1 also controls the alarm unit 5 to sound an alarm sound when receiving a fire alarm message by receiving a radio signal transmitted from another fire alarm device TR by the radio transmission / reception unit 2. Each of the fire alarms TR1, TR2,... Is assigned a unique identification code and stored in the memory unit 1a. The destination of the radio signal and the source fire alarms TR1, TR2,. Can be identified.

  The oscillator 6 oscillates an operation clock (clock signal) of a microcomputer constituting the control unit 1 using a tuning fork type crystal resonator. However, since the circuit configuration of the oscillator 6 is well known in the art, a detailed description thereof will be omitted.

  Here, in the radio equipment regulation Article 49-17 “Radio equipment of radio stations of the low power security system” of the Radio Law Enforcement Regulation, the period during which radio signals may be continuously transmitted (transmission period) is 3 seconds or less. It is stipulated that the period (pause period) provided between the transmission period and the transmission period in which the radio signal should not be transmitted is 2 seconds or more (see No. 5 of the same article). For this reason, in the control unit 1 in the present embodiment, the wireless signal is transmitted during the transmission period that complies with the wireless facility rules, and the transmission is stopped and received during the suspension period.

  Moreover, the control part 1 is performing the intermittent reception demonstrated by the prior art in order to lengthen the battery life of the battery power supply part 7 as much as possible. That is, the control unit 1 repeatedly counts a predetermined intermittent reception interval with a timer (timer means), and activates the wireless transmission / reception unit 2 every time the intermittent reception interval is counted, and activates a desired radio wave (other fire alarm TR It is checked whether or not the radio signal transmitted by can be received. And if the said electromagnetic wave is not caught, the control part 1 will stop the radio | wireless transmission / reception part 2 immediately, and will reduce average power consumption significantly by making it transfer to a standby state. The radio wave reception check is performed by the control unit 1 based on a received signal strength display signal (RSSI signal) which is a DC voltage signal output from the wireless transmission / reception unit 2 and proportional to the magnitude of the received signal strength.

  Further, the control unit 1 of a specific fire alarm device TR1 (hereinafter referred to as a parent device) activates the wireless transmission / reception unit 2 periodically (for example, every 24 hours), and other fire alarm devices TR2, TR3,. (Hereinafter referred to as a slave unit) is caused to transmit a radio signal including a regular monitoring message (response request message). In the child device TRi (i = 2, 3,...), The control unit 1 monitors the fire detection unit 4 for failure and the battery power supply unit 7 for battery breakage at regular intervals (for example, every hour). At the same time, the monitoring results (whether there is a failure and whether the battery has run out) are stored in the memory unit 1a. When a regular monitoring message is received from the parent device TR1, a radio signal including a notification message (response message) for notifying the monitoring result stored in the memory unit 1a is returned to the parent device TR1. After transmitting the radio signal including the notification message, the control unit 1 of the master unit TR1 switches the radio transmission / reception unit 2 to the reception state and receives the radio signal transmitted from each slave unit TRi. Then, the control unit 1 of the parent device TR1 determines that there is a child device TRi that does not transmit the notification message within a predetermined time from the transmission of the regular monitoring message, or when the monitoring result of the notification message is faulty or the battery is dead. A buzzer included in the alarm unit 5 is driven to sound a notification sound. As a result, it is possible to notify the user that an abnormality (communication failure, failure, battery exhaustion, etc.) has occurred in any slave unit TRi. When the control unit 1 of the master unit TR1 and the slave unit TRi determines that a failure or a battery has run out, the alarm unit 5 immediately gives a warning sound (such as a buzzer sound or a voice message) to notify the occurrence of an abnormality. Let it ring.

  The control unit 1 of the master unit TR1 transmits an alarm sound from the alarm unit 5 and transmits a fire alarm message to each slave unit TRi, or after receiving a fire alarm message from any slave unit TRi, is transmitted wirelessly. The unit 2 is caused to transmit a synchronous beacon at a constant cycle. This 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 TR. That is, one period (cycle) of the synchronous beacon is divided into a plurality of time slots, and one different time slot is allocated to each of the slave units TRi. The message from the parent device TR1 to the child device TRi is transmitted in the synchronization beacon, and the message from the child device TRi to the parent device TR1 is stored and transmitted in the time slot assigned to each child device TRi. The Therefore, collision of radio signals transmitted from a plurality of fire alarm devices TR (master device TR1 and slave device TRi) can be reliably avoided. The time slot assignment for each fire alarm device TR may be fixed, but the time slot assignment information may be notified to each child device TRi by a synchronous beacon transmitted from the parent device TR1.

  FIG. 2 shows a frame format of a radio signal transmitted and received by the fire alarm TR, including a synchronization bit (preamble: PA), a frame synchronization pattern (unique word: UW), a destination address DA, a source address SA, a message M, One frame is composed of the CRC code. Here, if the identification code of each fire alarm device TR is set as the destination address DA, only the fire alarm device TR of the identification code receives a radio signal and acquires a message. On the other hand, if a special bit string (for example, a bit string with all bits set to 1) that is not assigned to any fire alarm TR is set as the destination address DA, the wireless signal is broadcast (multicast) and all A message can be acquired by the fire alarm TR. For example, a radio signal including a fire alarm message is broadcast from the parent device TR1 to all the child devices TRi.

  Next, the transmission / reception operation of this embodiment before and after the fire detection will be described with reference to the time chart of FIG.

  Here, the timing at which each fire alarm device TR starts to operate (the timer starts counting the intermittent reception interval) does not normally match, so the timing at which the control unit 1 activates the wireless transmission / reception unit 2 to receive radio waves ( (See the downward arrow in FIG. 3). On the other hand, in the present embodiment, when the synchronization signal is received by the radio transmission / reception unit 2 of each fire alarm device TR, the control unit 1 stops the counting of the intermittent reception interval Tx by the timer and ends the synchronization signal ( When a certain waiting time Tw elapses from t = t0), the counting of the intermittent reception interval Tx by the timer is resumed. Therefore, after receiving the synchronization signal, the timing at which the timer finishes counting the intermittent reception interval Tx is set in each fire alarm device TR. The synchronization signal is transmitted from the master unit TR1, which is a specific fire alarm, as will be described later.

  For example, when the fire detection unit 4 detects a fire in the child unit TR2, the control unit 1 of the child unit TR2 sounds an alarm sound from the alarm unit 5 and sets the wireless transmission / reception unit 2 before the completion of the intermittent reception interval Tx by the timer. to start. Then, the control unit 1 of the slave unit TR2 transmits the radio signal including the fire alarm message to all the other fire alarm devices TR (the master unit TR1 and the other slave units TR3,...) Within the transmission period including the count completion time. Send to. At this time, the control unit 1 of the slave unit TR2 as the transmission source 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. Since each fire alarm device TR has the timing to complete the intermittent reception interval Tx, it is possible to receive a radio signal including a fire alarm message in one transmission period.

  Here, if low-power radio is used, the wireless communication distance can be sufficiently covered as long as it is within an area of a normal house. Therefore, the child unit TR2 of the fire source is connected to other fire alarms TR (master unit TR1 and It is usually possible to send a message to other child units TR3,. Further, as described above, the parent device TR1 periodically monitors the child devices TR2 to TR4, and the normality of the communication path is confirmed between the parent device TR1 and each child device TR2 to TR4. . However, since the communication path between the child devices TR2 to TR4 is not confirmed, there is a possibility that a message does not reach a certain child device due to the influence of an obstacle, for example.

  Therefore, the control unit 1 of the master unit TR1 that has received the fire alarm message sends a radio signal including the fire alarm message to the other slave units TR3 and TR4 other than the slave unit TR2 that is the transmission source, and an intermittent reception interval Tx by the timer. It is transmitted in the transmission period including the time point of completion of counting. When the control unit 1 of the other slave units TR3 and TR4 receives the fire alarm message transmitted from the slave unit TR2 or the master unit TR1, it immediately sounds an alarm sound from the alarm unit 5 and sends a fire alarm message from the wireless transceiver unit 2. A response message (ACK) for confirming reception is returned by a radio signal. In addition, when all of the fire alarms TR notify a fire alarm (sound an alarm sound) when a fire is detected by at least one fire alarm TR in this way, it is hereinafter referred to as “fire interlocking”. .

  When the control unit 1 of the parent device TR1 receives ACK from all the other child devices TR3 and TR4, the control unit 1 causes the wireless 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 TS1 is assigned to the child device TR2, the second time slot TS2 is assigned to the child device TR3, and the third time slot TS3 is assigned to the child device TR4.

  Here, the parent device TR1 regularly monitors each child device TR2 to TR4, and the normality of the communication path is confirmed between the parent device TR1 and each child device TR2 to TR4. The communication path between the devices TR2 to TR4 has not been confirmed. When a large number of slave units TRi are arranged, the number of communication paths between the slave units TRi becomes very large. Therefore, when the normality of the communication paths between the slave units TRi is confirmed, battery consumption becomes severe. Therefore, as described above, a specific fire alarm device TR1 is used as a parent device, and other fire alarm devices TRi are used as child devices, so that a fire alarm message and other messages (described later) are notified from the parent device TR1 to each child device TRi. Thus, even if there are slave units that cannot establish a communication path with each other, it is possible to make sure that the fire is linked.

  When all the fire alarm devices TR sound an alarm sound, the synchronization is started, and as described above, a synchronization beacon is transmitted from the master device TR1 at a constant cycle, and the operation shifts to TDMA synchronous communication. In the synchronous communication, the control unit 1 of the parent device TR1 repeatedly transmits a fire alarm message to all the child devices TRi at regular intervals by being included in the synchronization beacon. And the control part 1 of each subunit | mobile_unit TRi confirms the state of the alarm part 5 whenever it receives the fire alarm message transmitted from the main | base station TR1, and if the alarm part 5 has stopped temporarily, it will ask the alarm part 5 again. Sound an alarm sound. Therefore, after fire alarms are started to be notified by all fire alarms TR, all other fire alarms (children) are placed in multiple time slots defined by the synchronized beacon transmitted by a specific fire alarm (master) TR1. ) Collision can be avoided by assigning TRi and performing wireless communication using time division multiple access (TDMA). In addition, the fire alarm message is included in the synchronous beacon periodically and sent to all other fire alarms (child units) TRi from a specific fire alarm (master unit) TR1. can do. As a result, a plurality of fire alarms TR can be effectively linked while avoiding radio signal collision.

  As described above, according to the present embodiment, since a fire alarm is notified by all the fire alarms TR in the event of a fire, the user has more opportunities to perceive the fire alarm (listen to the alarm sound), thereby increasing safety. Can be improved.

  By the way, the fire alarm system of this embodiment transits three operation states of a standby state, an interlocking ringing state, and an interlocking stop state. The standby state is a state in which no fire is detected in any fire alarm TR. The interlocking sounding state is a state where all the fire alarms TR are sounding an alarm sound. In addition, the interlock stop state means that only the fire alarm TR that detects fire (fire source) sounds the alarm sound and the fire alarm devices TR other than the fire source stop the alarm sound as described later. State. That is, when a fire is detected by at least one of the fire alarm devices TR (eg, child device TR2) in the standby state, as described above, all the other children from the fire child device TR2 and the parent device TR1. When the fire alarm message is transmitted to the devices TR3,..., An alarm sound is generated in all the fire alarm devices TR including the parent device TR1 and the child devices TR2,.

  When the operation input for stopping the alarm sound is received by the operation input receiving unit 7 of any fire alarm device TR in the interlocking sounding state, if the fire alarm device TR is the master device TR1, A message (alarm stop message) requesting stop of the alarm sound is transmitted from the device TR1 to all the child devices TRi. Alternatively, if the fire alarm device TR is the child device TRi, the parent device TR1 that has received the alarm stop message from the child device TRi transmits an alarm stop message to the other child devices TRi. Then, when the alarm stop message is received by the fire alarm device TR other than the fire source, the alarm sound of the alarm unit 5 is stopped and a transition to the interlock stop state is made. However, when an operation input for stopping the alarm sound is received by the operation input receiving unit 7 of the fire alarm device TR of the fire source, the alarm sound is also stopped in the fire alarm device TR of the fire source. Here, the control unit 1 of the master unit TR1 holds the fire detection status for each master unit TR1 and each slave unit TRi in the memory unit 1a while being updated as needed. Transition from the fire interlocking state to the standby state when no longer occurs.

  Further, when the interlocking sounding state is changed to the interlocking stop state, the control unit 1 of the parent device TR1 starts a time limit for a predetermined alarm sound stop time (for example, 5 minutes). After the alarm sound stop time has elapsed, the control unit 1 of the master unit TR1 refers to the fire detection status held in the memory unit 1a, and if all the fire alarms TR do not detect a fire, the control unit 1 Transition from the fire-linked state to the standby state by sending a recovery notification message using a beacon. On the other hand, if a fire is detected by at least one fire alarm device TR, a fire alarm message is transmitted by a synchronous beacon to make a transition from the interlock stop state to the interlock ringing state. Even if any fire alarm TR detects a new fire in the interlock stop state, the control unit 1 of the master unit TR1 transmits the fire alarm message by the synchronous beacon to switch from the interlock stop state to the interlock ringing state. Transition.

  For example, as shown in the time chart of FIG. 4, in a fire-linked state (linked ringing state) in which the parent device TR1 is a fire source, an operation input for stopping an alarm sound is received by the operation input reception unit 7 of the child device TR4 that is not a fire source When the alarm stop message is transmitted from the child unit TR4 by being accepted, the control unit 1 of the master unit TR1 that has received the alarm stop message transmits the alarm stop message M2 by the synchronous beacon and sets the time limit of the alarm sound stop time. Do. However, in the master unit TR1 that is the source of fire, the alarm unit 5 continues to sound an alarm sound. After the alarm sound stop time has elapsed, the control unit 1 of the parent device TR1 confirms the fire detection status of its own fire detection unit 4 and the fire detection status of the child device TRi. When at least one of the fire alarms TR detects a fire, the control unit 1 of the master unit TR1 transmits a fire alarm message to each slave unit TRi again by using a synchronous beacon so that the slave unit TR1 can be stopped. Transition to the linked ringing state.

  On the other hand, as shown in the time chart of FIG. 5, if the fire is extinguished within the alarm sound stop time and the fire detection unit 4 stops detecting the fire, the control unit 1 of the master unit TR1 After the elapse, a recovery notification message is transmitted to each slave unit TRi by a synchronous beacon. When the ACK returned from all the slave units TRi is received, the control unit 1 of the master unit TR1 shifts from the interlock stop state to the standby state, and stops the transmission of the synchronous beacon, thereby performing wireless communication by the TDMA method. Return to wireless communication by intermittent transmission and reception.

  In addition, as shown in the time chart of FIG. 6, if the fire of the fire source is extinguished and the fire detection unit 4 of the child device TR4 does not detect the fire in the interlocking ringing state using the child device TR4 as the fire source, A recovery notification message is transmitted from the device TR4 to the parent device TR1. The control unit 1 of the master unit TR1 that has received the recovery notification message refers to the fire detection status held in the memory unit 1a. If no fire is detected by all the fire alarms TR, the recovery notification message is sent by a synchronous beacon. M3 is transmitted to each slave unit TRi. When the control unit 1 of the master unit TR1 receives ACKs returned from all the slave units TRi, the state transitions from the interlocking stop state to the standby state, and the transmission of the synchronous beacon is stopped, thereby intermittently starting the wireless communication by the TDMA method. Return to wireless communication by transmission and intermittent reception.

  On the other hand, as shown in the time chart of FIG. 7, when a fire is newly detected by another fire alarm device (eg, child device TR3), a recovery notification message is received from the child device TR4 which is the first fire source. The control unit 1 of the parent device TR1 refers to the fire detection status held in the memory unit 1a. At this time, the control unit 1 of the parent device TR1 does not transmit the recovery notification message because the child device TR3 is detecting a fire, and continues to transmit the fire alarm message to maintain the fire-linked state.

  Here, in this embodiment, the timing which the control part 1 of each fire alarm device TR starts the radio | wireless transmission / reception part 2 is prepared by receiving a synchronizing signal. In addition, since the control unit 1 of the fire alarm device TR that has detected a fire transmits a radio signal in accordance with the activation timing, all the other fire alarm devices TR transmit the radio signal transmitted from one fire alarm device TR. It can be received almost simultaneously. As a result, the delay time until another fire alarm TR can receive the radio signal transmitted by one of the fire alarms TR while shortening the power consumption and extending the battery life by performing intermittent reception is shortened. be able to.

  Moreover, every time the transmission / reception control means (control unit 1) of a specific radio station (master unit TR1) among a plurality of radio stations (fire alarm device TR) completes the count of the intermittent reception interval by the timer means a predetermined number of times. If the synchronization signal is transmitted from the transmission / reception means (wireless transmission / reception unit 2), there is an advantage that a dedicated transmitter (transmission station) or the like for transmitting the synchronization signal is unnecessary and the system configuration can be simplified.

  In the present embodiment, since a specific radio station (master device TR1) transmits a radio signal including a regular monitoring message to other radio stations (child device TRi) at a constant period, the regular radio message is included. A radio signal may also be used as a synchronization signal.

  By the way, the intermittent reception interval is counted by counting the operation clock (the clock signal oscillated by the oscillator 6; the same shall apply hereinafter) by the microcomputer constituting the control unit 1. Since the vibration frequency of the tuning-fork type crystal resonator used for the oscillator 6 (= the oscillation frequency of the oscillator 6) is generally 32.768 kHz, for example, when the intermittent reception interval is 10 seconds, the control unit 1 is for operation. Intermittent reception is performed every time the clock is counted 327680 (= 32.768kHz × 10s). However, the frequency stability (frequency deviation) of the tuning fork type crystal resonator is about several tens of ppm, and there are individual differences. Therefore, when a tuning-fork type crystal resonator with a large frequency deviation is used for the oscillator 6, the time difference of the intermittent reception interval gradually increases due to long-term use, and synchronization is performed between the parent device TR1 and the child device TRi. There is a risk that the intermittent reception interval due to the signal may not be synchronized (out of synchronization will occur).

  Therefore, in the present embodiment, when the wireless transmission / reception unit 2 receives the synchronization signal, the time difference detection means for detecting the time difference between the reception timing of the synchronization signal and the intermittent reception interval counted by the timer, and the time difference detection means The slave unit TRi includes correction means for correcting the count operation of the timer so as to reduce the detected time lag. However, both the time shift detection means and the correction means are realized by causing the microcomputer of the control unit 1 to execute a dedicated program.

  As shown in FIG. 8, when the synchronization signal has a frame structure composed of a preamble and a unique word (UW), the control unit 1 serving as a time lag detection means completes the reception of the unique word from the time t0 when the preamble of the synchronization signal is received. The time (detection time) until time t1 is measured. For example, assuming that the time width of the synchronization signal is T (seconds) and the intermediate value (= T / 2) of the synchronization signal is a reference point for time shift detection, the time shift ΔT is calculated as ΔT = detection time−T / 2. (See FIG. 8).

  Alternatively, as shown in FIG. 9, the frame structure of the synchronization signal includes a header HD consisting of a bit synchronization preamble and a frame synchronization unique word, and a data field to which numbers (continuous transmission numbers) are assigned in order from the beginning. In the case of a frame configuration in which a plurality of pairs of synchronous frames are continuously transmitted, the control unit 1 serving as a time lag detection means continuously transmits the serial number i (i = 1, 2,...) Of the data field received first in intermittent reception. , n) to detect the time lag. For example, assuming that the serial number i of the synchronization frame received first is i = 2 when the serial number i assigned to the data field is based on the synchronization frame of n / 2, the time shift ΔT is ΔT. = T * (n / 2-2).

  Alternatively, instead of the above-described serial number i, a time lag value (0 ppm, ± 1 ppm,..., ± 10 ppm) with the intermediate value of the synchronization signal as a reference point is stored in the data field as shown in FIG. The control unit 1 serving as a time lag detection means can detect the time lag ΔT from data (0 ppm, ± 1 ppm,..., ± 10 ppm) received first in intermittent reception.

  Next, correction processing of the control unit 1 serving as correction means will be described. The control unit 1 corrects the time lag ΔT detected by the above-described method or the like by finely adjusting the count operation of the timer according to the magnitude of ΔT. That is, since the intermittent reception interval Tx can be changed by increasing / decreasing the count value of the timer that counts the intermittent reception interval Tx from the regular value, the control unit 1 can increase the time by increasing / decreasing the timer count value. The shift ΔT can be corrected. Here, as described above, the tuning fork type crystal oscillator normally oscillates at 32.768 kHz. For example, when the intermittent reception interval Tx is 5 seconds, intermittent reception is performed every count of 163840 (= 32.768 kHz × 5). Therefore, the amount of change when increasing or decreasing by one count is approximately ± 6 ppm (≈1 ÷ 163840), which is the minimum unit that can be corrected. Therefore, since it cannot correct | amend that the detected time shift | offset | difference (DELTA) T is a value smaller than the said minimum value, in this case, the control part 1 performs increase / decrease in a count value at a rate of once every 10 minutes, for example. To correct the time difference ΔT. Note that the count value is increased or decreased immediately before the accumulated time lag exceeds the upper limit value, with the time during which the synchronization signal can be received (a value slightly smaller than half the time width T of the synchronization signal) being the upper limit value. It doesn't matter if you do.

  Furthermore, in the present embodiment, a radio signal including information on the time lag of the intermittent reception interval (time lag ΔT detected by the control unit 1) is transmitted from each slave unit TRi to the master unit TR1, and the radio signal is received. The control unit 1 of the master unit TR1 adjusts the period of the synchronization signal based on the value of the time shift ΔT. Specifically, as shown in Table 1 below, the magnitude (value) of the time lag ΔT is ranked in five stages, and the rank of the synchronization signal is set shorter as the rank of the time lag ΔT is larger (rank with a larger number). is doing. The correspondence relationship shown in Table 1 below is stored as a data table in the memory unit 1a of the parent device TR1.

  The control unit 1 of the master unit TR1 acquires the information of the time shift ΔT returned from each slave unit TRi with the wireless transmission / reception unit 2 in the reception state after transmitting the synchronization signal, and acquires the time shift ΔT acquired from each slave unit TRi. The period corresponding to the rank having the largest value is set as the period of the next synchronization signal. For example, when the time lag ΔT of one of the child devices TRi is 600 msec and the time lag ΔT of the other child device TRi is less than 400 msec, the control unit 1 of the parent device TR1 corresponds to rank 2 of the time lag ΔT = 600 msec. 20 hours is set as the period of the synchronization signal.

  Thus, conventionally, since the period of the synchronization signal is uniformly set to 8 hours based on the specifications of the oscillator (tuning fork type crystal resonator) used for the oscillator 6, the synchronization signal is generated with a period shorter than necessary. The battery life of the parent device TR1 and the child device TRi was shortened by being transmitted. On the other hand, in the present embodiment, since the control unit 1 of the parent device TR1 adjusts the period of the synchronization signal based on the actual frequency deviation value of the oscillator used for the oscillator 6, While preventing loss of synchronization, it is possible to extend battery life by suppressing power consumption associated with transmission of synchronization signals and detection of time lag ΔT. Instead of transmitting the value of the time shift ΔT from the slave unit TRi to the master unit TR1, the rank (numbers 1 to 5) in Table 1 may be transmitted. In this case, however, it is necessary to store the correspondence between the ranks in Table 1 and the period of the synchronization signal in the memory unit 1a of each slave unit TRi.

(Embodiment 2)
Since the system configuration of this embodiment and the configuration of the fire alarm device TR, which is a radio station, are the same as those of the first embodiment, common components are denoted by the same reference numerals, and illustration and description thereof are omitted.

  In the present embodiment, the manufacturer of the fire alarm device TR measures the frequency deviation of the oscillator 6 of each fire alarm device TR in the inspection process, and stores the measured value in the memory unit 1a as information on the time difference. In the inspection process, the frequency deviation of the oscillator 6 can be measured by a measuring instrument using a high-precision crystal resonator (for example, an AT cut crystal resonator) having a frequency deviation of several ppm or less.

  Then, in the work (registration work) in which the parent device TR1 and the child device TRi register each other's identification code before the start of system operation, information on time lag (measured value of frequency deviation) from each child device TRi to the parent device TR1. ) And the control unit 1 of the parent device TR1 adjusts the period of the synchronization signal based on the measurement value acquired from each child device TRi by a radio signal.

  The registration work is started when an operation input of the registration work is received by the operation input receiving unit 7 in each of the parent device TR1 and the child device TRi. The registration work will be described below with reference to the sequence diagram of FIG.

  When the operation input of the registration work is received by the operation input receiving unit 7, the control unit 1 of the slave unit TRi shifts to the registration mode, and information on the time difference stored in the registration request message and the memory unit 1a (described later) A wireless signal including (frequency deviation rank) is transmitted (multicast) from the wireless transmission / reception unit 2. When the operation input for the registration work is received by the operation input receiving unit 7, the control unit 1 of the parent device TR1 sets the wireless transmission / reception unit 2 to the reception state. When the wireless signal transmitted from the child device TRi is received by the wireless transmission / reception unit 2, the control unit 1 of the parent device TR1 is included in the transmission source address (identification code of the child device TRi) and the wireless signal. The information about the time lag that has been stored is associated with each other and stored in the memory unit 1a, and a wireless signal including a registration command is transmitted from the wireless transmission / reception unit 2 to the child device TRi.

  When the wireless signal transmitted from the parent device TR1 is received by the wireless transmission / reception unit 2, the control unit 1 of the child device TRi receives the transmission source address (identification code of the parent device TR1) of the wireless signal including the registration command message in the memory unit 1a. And the wireless transmission / reception unit 2 returns a wireless signal including ACK to the parent device TR1, and the registration mode is terminated. The control unit 1 of the parent device TR1 ends the registration mode when the wireless transmission / reception unit 2 receives a wireless signal including ACK transmitted from the child device TRi.

  Here, in the memory unit 1a of the parent device TR1, a data table (corresponding to the correspondence between the measured value of the frequency deviation ranked in five stages and the period of the synchronization signal corresponding to each rank (frequency deviation rank)). Table 2 below is stored.

  The control unit 1 of the master unit TR1 refers to the data table stored in the memory unit 1a, and next determines the cycle corresponding to the rank having the largest value among the measured values of frequency deviation obtained from each slave unit TRi. Set to the period of the sync signal. For example, when the measurement value of the frequency deviation of one of the child devices TRi is 13 ppm and the measurement value of the frequency deviation of the other child device TRi is less than 5 ppm, the control unit 1 of the parent device TR1 has a frequency deviation of ± 10 ppm to 15 ppm. 16 hours corresponding to the frequency deviation rank 3 is set as the period of the synchronization signal.

  Thus, also in this embodiment, since the control unit 1 of the parent device TR1 adjusts the period of the synchronization signal based on the actual frequency deviation value of the oscillator used for the oscillator 6, While preventing loss of synchronization, it is possible to extend battery life by suppressing power consumption associated with transmission of synchronization signals and detection of time lag ΔT. Instead of transmitting the measurement value of the frequency deviation from the slave unit TRi to the master unit TR1, the frequency deviation rank (numbers 1 to 5) in Table 2 may be transmitted. However, in that case, it is necessary to store the correspondence between the frequency deviation rank and the period of the synchronization signal in Table 2 in the memory unit 1a of each slave unit TRi.

  Here, when the frequency deviation of the parent device TR1 and the frequency deviation of the child device TRi are greatly different, for example, when the respective frequency deviation ranks do not match, the period of the synchronization signal is set shorter than necessary. Therefore, it is not preferable to configure a system with the parent device TR1 and the child device TRi.

  Therefore, in the control unit 1 of the parent device TR1, when the frequency deviation rank acquired from the child device TRi at the time of the registration work matches the own rank stored in the memory unit 1a, the registration is performed for the child device TRi. A radio signal including a command message is transmitted, and if they do not match, a radio signal including a message indicating that registration cannot be performed is transmitted, and registration of the child unit TRi is rejected. As a result, the parent device TR1 and the child device TRi whose frequency deviation ranks do not coincide with each other is not mixed in the same system, and the battery life can be extended by suppressing power consumption in the entire system.

TR1 Fire alarm (master unit)
TR2 Fire alarm (child unit)
1 Control unit (transmission / reception control means, timer means, time lag detection means, correction means)
2 Wireless transmission / reception unit (transmission / reception means)
6 Oscillator 7 Battery power supply (power supply means)

Claims (7)

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 radio station transmits / receives a radio signal, timer means for repeatedly counting a certain intermittent reception interval, and activates the transmitter / receiver when a predetermined event occurs, and the event is transmitted during a predetermined transmission period. The operation of transmitting and receiving a radio signal including a message corresponding to the above and repeating the operation of pausing the transmission of the radio signal during a predetermined pause period and stopping the transmission / reception means when the event has not occurred, further, the timer means The transmission / reception means is stopped during counting of the intermittent reception interval by the transmission / reception control means for starting the transmission / reception means each time counting of the intermittent reception interval by the timer means is completed; Power supply means for supplying operating power,
The timer means is configured to count the intermittent reception interval by counting a clock signal having a fixed period oscillated by an oscillator.
The transmission / reception control means stops counting the intermittent reception interval by the timer means when the synchronization signal is received by the transmission / reception means, and the timer when a certain waiting time has elapsed since the end of the synchronization signal. The intermittent reception interval counting by the means is resumed. Further, when the event occurs, a radio signal is transmitted from the transmission / reception means during the transmission period overlapping with the time when the intermittent reception interval counting by the timer means is completed. ,
When the synchronization signal is received by the transmission / reception means, a time lag detection means for detecting a time lag between the reception timing of the synchronization signal and the intermittent reception interval counted by the timer means, and detected by the time lag detection means. A correction means for correcting the counting operation of the timer means so as to reduce the time lag of each radio station,
The transmission / reception control means of a specific wireless station among the plurality of wireless stations causes the transmission / reception means to periodically transmit a synchronization signal at a period sufficiently longer than the intermittent reception interval,
The transmission / reception control means of other radio stations excluding the specific radio station causes the radio signal including information on the time difference of the intermittent reception interval by the timer means to be transmitted from the transmission / reception means to the specific radio station,
The transmission / reception control unit of the specific radio station adjusts the period of the synchronization signal based on information on the time shift included in the radio signal transmitted from the other radio station. Communications system.   The radio communication system according to claim 1, wherein the transmission / reception control unit of the other radio station uses the detection result of the time shift detection unit as information on the time shift.   3. The radio according to claim 2, wherein the time lag detecting means ranks the magnitude of the time lag, and the transmission / reception control means of the other radio station uses the rank as information relating to the time lag. Communications system.   The other radio station includes storage means for storing information on a frequency deviation of a clock signal oscillated by the oscillator, and the transmission / reception control means of the other radio station is configured to store the frequency deviation stored in the storage means. The wireless communication system according to claim 1, wherein the information is information regarding the time lag.   5. The wireless communication system according to claim 4, wherein the storage means stores a frequency deviation rank corresponding to the magnitude of the frequency deviation as information on the frequency deviation.   6. The transmission / reception control unit of the other radio station transmits a radio signal including information about the time lag from the transmission / reception unit to the specific radio station before starting operation of the system. The wireless communication system described. The specific radio station includes storage means for storing a frequency deviation rank corresponding to the magnitude of the frequency deviation of the clock signal oscillated by the oscillator,
The transmission / reception control unit of the specific radio station transmits a radio signal using only the radio station having the same frequency deviation rank as the own frequency deviation rank stored in the storage unit as the other radio station. The wireless communication system according to claim 6.