JP4674587B2 - Wireless transmission system - Google Patents

Description

  The present invention relates to a wireless transmission system for transmitting a wireless signal between a plurality of wireless devices.

  For radio equipment used in Japan, the characteristics of radio waves used (RF characteristics) such as occupied frequency bandwidth and adjacent channel leakage power must satisfy the regulations of the Radio Law. In the Radio Law, different standards (communication standards) are defined for each purpose of use. For example, the “specified low-power radio station” defined in Article 6 of the Radio Law Enforcement Regulations uses a telemeter for automatically displaying or recording the measurement results of remote measuring devices using radio waves. , For telecontrol that transmits signals for the purpose of starting, changing or terminating the function of a device at a remote location using radio waves, and transmission of information processed mainly by machines or transmission of processed information "Specified low-power radio station telemeter, telecontrol and data transmission radio equipment standard (Radio Industry Association Standard ARIB STD-T67)" or mainly fire "Small power," which is defined for wireless facilities of low power security systems that report theft or other abnormalities or perform incidental controls. Curie tee system of the radio station radio equipment standards (Association of Radio Industries and Businesses Standard RCR STD-30) ", and the like.

  On the other hand, as a radio transmission system provided with the specific low-power radio station, there is a fire alarm system described in Patent Document 1, for example. Such a fire alarm system has a function in which a plurality of fire detectors (radio units) installed at multiple locations detect a fire and sound a warning sound, respectively. When a fire is detected, the relevant fire detector sounds an alarm sound and transmits information (fire detection information) to notify the fire detection to other fire detectors by wireless signals. A plurality of fire detectors interlock and sound an alarm sound all at once, so that the occurrence of a fire can be notified quickly and reliably.

Such a fire detector (wireless device) is driven by a battery in order to take advantage of the characteristic of transmitting fire detection information with a radio signal, and is usually used for maintenance (battery replacement) like an indoor ceiling. Since it is installed in a difficult place, it is desirable that it can be used without maintenance for a long period of time such as several years. Therefore, each fire detector intermittently activates a receiving circuit to check whether or not a desired radio wave (a radio signal transmitted by another fire sensor) can be received. It is desired to significantly reduce the average power consumption by stopping the receiving circuit and shifting to the standby state.
JP 2006-343983 A

  By the way, in the above-mentioned standard for the specific low-power radio station, the period (transmission period) during which radio waves can be continuously transmitted from the radio station (radio unit) and the period during which radio waves should not be transmitted (pause period) are specified. Therefore, a wireless signal cannot be received unless the timing of intermittent reception matches the transmission period. In addition, during the transmission period, a radio signal having a data format including at least a synchronization bit, a frame synchronization pattern, a message, and a CRC code as one frame is continuously transmitted for several frames. Even if the synchronization is possible, the specification shifts to a suspension period when a message error or CRC error occurs. If a reception error occurs in this way, the radio wave check is not performed unless a certain time (intermittent reception interval) has passed again, and the timing for receiving a radio signal is delayed.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wireless transmission system capable of reducing the delay time of information transmission while reducing the power consumption of the wireless device.

  In order to achieve the above object, the present invention is a wireless transmission system that includes a plurality of wireless devices and transmits wireless signals between the plurality of wireless devices, and each wireless device transmits a wireless signal. At least one of receiving means and receiving means for receiving a radio signal, and a battery for supplying power in common, and a radio having a sending means has a predetermined bit pattern for identification within one frame of the radio signal. And a bit pattern insertion means for identifying that is inserted almost regularly, and a transmission means that is activated when a predetermined event occurs to transmit a radio signal during a predetermined transmission period and transmit a radio signal during a predetermined pause period. And a transmission control means for stopping the transmission means when the event has not occurred, and the radio having the reception means receives the signal at the reception means. An identification bit pattern detection means for detecting an identification bit pattern of a radio signal, a timer means for repeatedly counting a constant intermittent reception interval, a reception means being stopped during counting of the intermittent reception interval by the timer means, and a timer means Receiving control means for activating the receiving means each time counting of the intermittent reception interval is completed. The reception control means receives a radio signal when the receiving means catches a desired radio wave, If it is not captured, the receiving means is stopped, and if the identification bit pattern detecting means detects the identification bit pattern in the immediately preceding frame even if the radio wave of the current frame cannot be captured, the intermittent reception interval is suspended. And the timer means restarts the intermittent reception interval count and detects the identification bit pattern. And wherein the resuming counting without changing the intermittent reception interval.

  According to the present invention, even if the radio wave of the current frame cannot be captured, if the identification bit pattern is detected in the immediately preceding frame, it is estimated that the transmitting side radio has entered a pause period, and the intermittent reception interval Is set to a time equal to the pause period, and the counting of the intermittent reception interval by the timer means is restarted, so that the counting of the intermittent reception interval is completed at or immediately after the start of the next transmission period, and the wireless signal is received by the receiving means. As a result, it is possible to shorten the time until the wireless signal can be normally received, that is, the delay time of information transmission, while reducing the power consumption of the wireless device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram of this embodiment, and a radio transmission system is configured by a plurality of radio units TR (only two units are illustrated). In the following description, when the radio units TR are individually indicated, they are indicated as radio units TR1, TR2,..., TRn, and when collectively indicated, they are indicated as radio units TR.

  The radio TR transmits a radio signal using radio waves as a medium from the antenna 3 and receives a radio signal transmitted from another radio TR by the antenna 3, and an event generator having a microcomputer as a main component. When the occurrence of an event is notified from 4, the control unit 1 that causes the wireless transmission / reception unit 2 to transmit a radio signal including a notification message for notifying other radio units TR of the occurrence of the event, and when the event occurs The event generator 4 that notifies the controller 1 of the occurrence of the event, the notification unit 5 that notifies the controller 1 of the occurrence of the event from the event generator 4, and a battery such as a dry battery And a battery power supply unit 6 for supplying operating power to each unit. Each wireless device TR1, TR2,... Is assigned a unique identification code, and the destination of the wireless signal and the transmitting wireless devices TR1, TR2,.

  The radio transmission / reception unit 2 transmits / receives a radio signal using radio waves as a medium in accordance with “specific low-power radio stations” defined in Article 6 of the Radio Law Enforcement Regulations. Further, the event generation unit 4 detects suspiciously by detecting fire detection means for detecting a fire by detecting smoke, heat, flame, etc. generated by a fire or detecting a heat ray (infrared ray) emitted from a human body. Security anomaly detecting means for detecting an anomaly related to security such as an intruder, an operation input accepting means for accepting an operation input such as a push button switch. However, the fire detection means, the security abnormality detection means, and the operation input reception means are well known in the art and will not be described in detail.

  The control unit 1 realizes various functions to be described later by executing a program stored in the memory with a microcomputer. For example, when the event generation unit 4 has a fire detection means, when the event generation unit 4 notifies that the fire has been detected, the control unit 1 drives a buzzer included in the notification unit 5 to generate a notification sound. A radio that includes a notification message for notifying the occurrence of a fire in order to sound a notification sound of the occurrence of a fire in another radio device (fire detector) TR as well as notifying the occurrence of a fire by sounding an (alarm sound) The signal is transmitted from the wireless transmission / reception unit 2. In addition, when the wireless transmission / reception unit 2 receives a wireless signal transmitted from another wireless device TR (a wireless signal including a notification message for notifying the occurrence of a fire), the control unit 1 uses a buzzer included in the notification unit 5. Drive to sound an alarm sound. That is, in the control unit 1, when the event generation unit 4 is notified of the occurrence of an event such as fire detection, human body detection, operation input reception, etc., the notification unit 5 generates a notification sound and notifies the occurrence of the event. The wireless transmission / reception unit 2 has a function of transmitting a wireless signal including a notification message.

  Here, as described in the related art, “Standard Equipment for Specific Low Power Radio Station Telemeter, Telecontrol and Data Transmission (Radio Industry Association Standard ARIB STD-T67)” and “Low Power Security” In the radio equipment standard of the system radio station (Radio Industry Association Standard RCR STD-30) etc., the period during which radio signals may be transmitted continuously (transmission period), the transmission period and the transmission period A period (pause period) between which radio signals should not be transmitted is defined. For example, the standard ARIB STD-T67 specifies a transmission period of 40 seconds or less and a pause period of 2 seconds or more, and the standard RCR STD-30 specifies a transmission period of 3 seconds or less and a pause period of 2 seconds or more. In addition, the control unit 1 transmits radio signals in a transmission period and a pause period that conform to these standards.

  Further, in order to extend the battery life of the battery power supply unit 6 as much as possible, the control unit 1 repeatedly counts a predetermined time interval (intermittent reception interval) with a timer (timer means) built in the microcomputer and completes counting of the intermittent reception interval. Each time, the wireless transceiver 2 is activated to check whether or not a desired radio wave (a radio signal transmitted by another radio device TR) can be received. If the radio wave is not detected, the radio transceiver 2 is immediately stopped. The average power consumption is greatly reduced by shifting to the standby state. The radio wave reception check is performed based on the received signal strength indication signal (Receiving Signal Strength Indication: RSSI signal) output from the wireless transmission / reception unit 2 and is a DC voltage signal proportional to the magnitude of the received signal strength. The details are well known in the art and will be omitted.

  Further, the control unit 1 of a specific radio TR1 periodically activates the radio transmission / reception unit 2 to check whether the other radios TR2, TR3,. Transmits a radio signal including a confirmation message, receives the radio signal including a response message transmitted from each of the radio devices TR2,... And transmits the radio signal including the confirmation message. If there is a wireless device TR that does not transmit a wireless signal including a response message within a predetermined time, the wireless device TR is abnormal (battery) by driving a buzzer provided in the notification unit 5 to sound a notification sound. It also has a function of notifying that a break has occurred. That is, in the present embodiment, the control unit 1 corresponds to a transmission control unit and a reception control unit.

  FIG. 2A shows a data format of a radio signal transmitted / received by the radio equipment TR, and includes a synchronization bit (preamble: PA), a frame synchronization pattern (unique word: UW), a destination address DA, a source address SA, and a message. One frame is composed of M and CRC codes. Here, if the identification code of each wireless device TR is set as the destination address DA, only the wireless device TR of the identification code receives a radio signal and acquires a message. By setting a special bit string (for example, a bit string in which all bits are set to 1) that is not assigned to the TR, the radio signal can be broadcast (broadcast) and all the radio devices TR can acquire the message. . For example, a radio signal including a notification message for notifying the occurrence of an event such as a fire is broadcast to all the radio devices TR. Note that the control unit 1 causes the radio transmission / reception unit 2 to continuously transmit one frame of radio signals by the number that can be transmitted within one transmission period (see FIG. 2B).

  In this embodiment, in the message M from the destination address DA, the control unit 1 delimits original data (destination address DA, source address SA, message M) every 8 bits (1 byte), and 1 byte data. A predetermined bit pattern, for example, an 8-bit (1 byte) bit pattern in which 0 and 1 are alternately arranged (hereinafter referred to as an identification bit pattern) BP is periodically inserted between bits (Data). . Further, the data demodulated by the radio transmission / reception unit 2 is taken into the control unit 1, and the control unit 1 detects the identification bit pattern BP included in the data. That is, in the present embodiment, the control unit 1 corresponds to an identification bit pattern insertion unit and an identification bit pattern detection unit.

  Next, the transmission / reception operation of this embodiment will be described with reference to the flowchart of FIG.

  The control unit 1 repeatedly counts the intermittent reception interval by a timer (not shown), and activates the wireless transmission / reception unit 2 to execute a radio wave check using an RSSI signal every time the intermittent reception interval elapses. The control unit 1 starts the reception operation by the wireless transmission / reception unit 2 if the radio wave is detected by the radio wave check, and continues the reception operation if the frame synchronization is established within a predetermined time (one frame time). If the radio wave is not captured, the wireless transmission / reception unit 2 is stopped and the counting of the intermittent reception interval is restarted.

  When synchronization is established, the control unit 1 sequentially fetches the destination address DA, the source address SA, and the message M received and demodulated by the wireless transmission / reception unit 2, and further performs a transmission error check using a CRC code. If there is no transmission error and the signal can be received normally, the control unit 1 notifies the occurrence of an event (fire occurrence, etc.) by processing a process according to the content of the received message M, for example, by sounding a notification sound from the notification unit 5, and transmission error. If radio signal reception fails due to a radio wave, the radio wave check is performed again. At this time, if the radio wave is captured, the control unit 1 continues the reception operation without stopping the wireless transmission / reception unit 2, but if the radio wave is not captured, the control unit 1 stops the wireless transmission / reception unit 2 and counts the intermittent reception interval. Resume.

  On the other hand, if the frame synchronization is not achieved within the predetermined time, the control unit 1 performs the radio wave check again, and if the radio wave is not captured, the control unit 1 regards it as immediately after switching from the transmission period to the pause period, and sets the intermittent reception interval. The intermittent reception interval count by the timer is started at the same time as the pause period, and if the radio wave is not captured, the wireless transmission / reception unit 2 is stopped and the intermittent reception interval count is restarted.

  Here, it should normally be possible to receive a radio signal in the next frame following the radio wave checked frame, but if the intermittent reception interval count is completed just before the end of the transmission period, it will be transmitted due to the influence of noise, etc. If reception of the radio signal of the last frame in the period fails, it can only be received when the intermittent reception interval count is completed again, and if the next intermittent reception interval count completion timing does not match the transmission period, Radio signal reception will be delayed.

  On the other hand, in this embodiment, even if reception of the radio signal fails, if the radio wave is detected by the radio wave check and the identification bit pattern BP is detected, the control unit 1 determines that the transmission period is in the pause period. Since the intermittent reception interval is set to the same time as the pause period and counting of the intermittent reception interval by the timer is started, as long as the transmitter-side radio TR is transmitting a radio signal, the pause period is set. The timing at which the counting of the intermittent reception interval set at the same time is completed must be consistent with the next transmission period. As a result, compared with the case where the intermittent reception interval is not changed to the same time as the pause period, the time until the wireless signal can be normally received, that is, the information transmission delay time can be shortened. When the identification bit pattern BP is not detected, it is assumed that some noise has been detected by the radio wave check, and the control unit 1 stops the wireless transmission / reception unit 2 and restarts counting without changing the intermittent reception interval. . In short, even if the transmitting side radio enters the pause period without detecting the frame synchronization pattern (unique word UW), the intermittent reception interval is set equal to the pause period if the identification bit pattern BP is detected. It is.

It is a system configuration figure showing an embodiment of the present invention. (A) is the data format of the radio signal in the above, and (b) is a time chart at the time of transmission. It is a flowchart for operation | movement description same as the above.

Explanation of symbols

1 control unit (identification bit pattern insertion means, identification bit pattern detection means, transmission control means, reception control means)
2 Radio transceiver (transmitting means, receiving means)
4 Event generation part 5 Notification part 6 Battery power supply part

Claims (1)

A wireless transmission system comprising a plurality of wireless devices and transmitting wireless signals between the plurality of wireless devices,
Each radio unit includes at least one of a transmission unit that transmits a radio signal or a reception unit that receives a radio signal, and a battery for power supply in common.
A radio apparatus having a transmission means activates the transmission means when a predetermined event occurs, and an identification bit pattern insertion means for inserting a predetermined identification bit pattern into a frame of a radio signal almost regularly. A transmission control means for alternately transmitting a radio signal during a predetermined transmission period and repeatedly stopping the transmission of the radio signal during a predetermined pause period and stopping the transmission means when the event has not occurred. ,
A radio apparatus having a receiving means includes an identification bit pattern detecting means for detecting an identification bit pattern of a radio signal received by the receiving means, a timer means for repeatedly counting a constant intermittent reception interval, and intermittent reception by the timer means. Receiving means for stopping the receiving means during counting of the interval, and starting the receiving means every time counting of the intermittent receiving interval by the timer means is completed,
The reception control means receives a radio signal when a desired radio wave is captured by the reception means, stops the reception means if the desired radio wave is not captured, and immediately before the radio wave of the current frame cannot be captured. If the identification bit pattern detection means detects the identification bit pattern in the frame, the intermittent reception interval is changed to a time equal to the pause period, and the counting of the intermittent reception interval by the timer means is restarted. If not detected, the wireless transmission system restarts counting without changing the intermittent reception interval.

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