JP2009177340A - Radio transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a uselessly consumption of a battery by receiving an undesired wave. <P>SOLUTION: If timing to detect synchronous bit pattern Sync by a control unit 1 that is a synchronous bit pattern detection means, agrees with the period, the control unit 1 that is a discrimination means, discriminates that it is a normal radio signal, and if the timing does not agree with the period, the control unit 1 discriminates that it is not a normal radio signal. The control unit 1 that is a control means further stops radio transceiving unit 2 that is a receiving means in a case that it is discriminated not to be a normal radio signal. Therefore, it is possible to discriminate whether the received radio wave is a desired wave or an undesired wave by whether the synchronous bit pattern Sync is included or not, moreover, if it is an undesired wave, it is possible to uselessly consume the battery by immediately stopping the radio transceiving unit 2 that is a receiving means. <P>COPYRIGHT: (C)2009,JPO&INPIT

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 point 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 the wireless facilities of the low power security system that reports theft or other abnormalities or controls associated therewith 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 in many places sense a fire and sound a warning sound. When a fire is detected, the fire detector sounds an alarm sound and transmits information (fire detection information) to notify the fire detection to other fire detectors by wireless signals, so that not only the fire source fire detector. 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

  However, if it detects a radio wave (unwanted wave) that you do not want to receive, such as a radio wave used in other wireless transmission systems or a radio wave (noise) generated from a device, the receiver circuit will start and the battery will There was a risk of being wasted.

  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 preventing wasteful consumption of batteries by receiving undesired waves. .

  In order to achieve the above object, a first aspect of the present invention is a wireless transmission system including a plurality of wireless devices and transmitting wireless signals between the plurality of wireless devices, wherein each wireless device transmits a wireless signal. At least one of transmitting means for transmitting or receiving means for receiving a radio signal and a battery for supplying power are commonly provided, and a radio having the transmitting means has 0 and 1 in one frame of the radio signal. Synchronization bit pattern detection means for detecting a synchronization bit pattern of a radio signal received by the reception means. And the timing at which the synchronization bit pattern detection means detects the synchronization bit pattern matches the period, it is determined that the signal is a normal radio signal and A determination means for determining that the wireless signal is not a normal wireless signal if the signal does not match the period, and a control means for stopping the reception means when the determination means determines that the wireless signal is not a normal wireless signal. To do.

  According to a second aspect of the present invention, in the first aspect of the invention, the wireless device including the receiving means has a detection means for detecting the intensity of the radio wave received by the receiving means, and the intensity of the radio wave detected by the detection means is a predetermined threshold value. And the control means of the radio device operates the synchronous bit pattern detection means if the radio wave intensity exceeds the threshold value according to the comparison result of the comparison means, and the radio wave intensity exceeds the threshold value. Otherwise, the receiving means is stopped without operating the synchronous bit pattern detecting means.

  The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the judging means judges whether or not the radio signal is normal during reception of the radio signal.

  The invention of claim 4 is the invention of any one of claims 1 to 3, wherein the radio signal transmitted by the transmission means has a frame configuration including a unique word for establishing frame synchronization, and a synchronization bit pattern The inserting means inserts a synchronization bit pattern into a portion excluding the unique word in one frame.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, the wireless signal transmitted by the transmission means has a frame configuration including a unique word for establishing frame synchronization, and a synchronization bit pattern The inserting means inserts a synchronous bit pattern in which the order of 0 and 1 is changed only in a unique word portion in one frame.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the synchronization bit pattern insertion means sets the synchronization bit pattern to 1 byte length.

  A seventh aspect of the invention is characterized in that, in the invention of any one of the first to sixth aspects, the transmission means performs non-return-zero coding on information transmitted by a radio signal.

  According to the present invention, if the timing at which the synchronization bit pattern detection unit detects the synchronization bit pattern coincides with the period, the determination unit determines that the signal is a normal radio signal, and the timing matches the period. Otherwise, the determination means determines that the radio signal is not normal, and the control means stops the reception means when the determination means determines that the radio signal is not normal. It is possible to determine whether the received radio wave is a desired wave or an undesired wave, and if it is an undesired wave, it is possible to prevent wasteful consumption of the battery by immediately stopping the receiving means.

  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 transmits a radio signal for notifying the occurrence of the event to the other radio equipment TR from the wireless transmission / reception unit 2, and the occurrence of the event when the event occurs The event generating unit 4 that notifies the control unit 1, the notification unit 5 that notifies the event generation unit 4 that the event has been notified to the control unit 1, and a battery such as a dry battery as a power source. And a battery power supply unit 6 for supplying power. A unique identification code (address) is assigned to each of the radio devices TR1, TR2,..., And the destination of the radio signal and the radio devices TR1, TR2,.

  The radio transmission / reception unit 2 transmits / receives a radio signal using a radio wave as a medium by modulating / demodulating a carrier wave having a specified frequency in a data format to be described later. It conforms to “Power Radio Station” and “Weak Radio Station”. 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 of the occurrence of a fire in other radio units (fire detectors) 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.

  In order to make the battery life of the battery power supply unit 6 as long as possible, the control unit 1 intermittently activates the radio transmission / reception unit 2 at predetermined time intervals (intermittent reception intervals) to check whether radio waves can be received. If radio waves are not captured, the wireless power transmission / reception unit 2 is immediately stopped to shift to a standby state, thereby greatly reducing the average power consumption. 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.

  FIG. 2 shows a data format of a radio signal transmitted / received by the radio TR, and includes a synchronization bit (preamble: PA), a frame synchronization pattern (unique word: UW), a destination address DA, a source address SA, a message M, and a CRC. One frame is constituted by a code. Here, in this embodiment, as shown in FIG. 2A, after the frame synchronization pattern (unique word) UW, the control unit 1 performs the original data (frame synchronization pattern UW, destination address DA, transmission source address SA, Message M, CRC code) is divided every 8 bits (1 byte), and an 8-bit (1 byte) synchronous bit pattern Sync (01010101) in which 0 and 1 are alternately arranged between 1 byte of data bits (Data) Is inserted. Further, the data demodulated by the wireless transmission / reception unit 2 is taken into the control unit 1, and the control unit 1 detects the synchronization bit pattern Sync included in the data. That is, in the present embodiment, the control unit 1 corresponds to a synchronization bit pattern insertion unit and a synchronization 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. Further, the control unit 1 starts the reception operation by the wireless transmission / reception unit 2 when radio waves are captured by the radio wave check, and stops the radio transmission / reception unit 2 when radio waves are not captured by the radio wave check. The wireless transmitter / receiver 2 synchronizes data transmitted by a wireless signal with a synchronization bit PA of multiple bytes that repeats 0 and 1 alternately, and normal reception operation is possible when synchronization is achieved with the synchronization bit PA become.

  After the synchronization by the synchronization bit PA is achieved, the control unit 1 detects the synchronization bit pattern Sync from the data received within a predetermined time (synchronization bit pattern Sync cycle: 2 bytes). If the synchronization bit pattern Sync cannot be detected within a predetermined time, it is determined that the received radio wave is an undesired wave, and the reception operation is interrupted and the wireless transmission / reception unit 2 is stopped. If the received radio wave is a desired wave, the control unit 1 takes in the data demodulated by the radio transmission / reception unit 2 byte by byte. At this time, since the synchronization bit pattern Sync is inserted into the frame synchronization pattern UW at a cycle of 2 bytes, the control unit 1 detects the synchronization bit pattern Sync that should be included in the data of 2 bytes, and is synchronized. If the timing for detecting the bit pattern Sync matches the cycle (2 bytes), the reception operation is continued. If the synchronization bit pattern Sync is not detected or the detection timing does not match the cycle, the reception operation is continued. The wireless transmission / reception unit 2 is stopped by interrupting.

  Then, if the frame synchronization pattern UW cannot be normally received within a predetermined time, the control unit 1 stops the reception operation and stops the wireless transmission / reception unit 2, and if the frame synchronization pattern UW can be normally received, the destination address DA is assigned to itself. It is determined whether it matches the assigned address or the broadcast address, and if it does not match either, it is data that does not need to be received, so the reception operation is interrupted and the wireless transmission / reception unit 2 is stopped. On the other hand, if the destination address DA matches either the address assigned to itself or the address for broadcasting, the remaining data (source address SA, message M, CRC code) is received and one frame is received. Capture data byte by byte until completion. At this time, since the synchronization bit pattern Sync is also inserted in the destination address DA, the transmission source address SA, and the message M in a 2-byte cycle, the control unit 1 receives if the synchronization bit pattern Sync is detected in a 2-byte cycle. The operation is continued, but when the synchronization bit pattern Sync is not detected in a 2-byte cycle, the reception operation is interrupted and the radio transmission / reception unit 2 is stopped. That is, since the undesired wave accidentally has the same bit string as the sync bit pattern Sync, even if the control unit 1 erroneously determines that it is the desired wave once, while receiving one frame of data, Again, it can be correctly determined that the wave is undesired. Then, if the transmission error check using the CRC code is not passed, the control unit 1 discards the received data and stops the wireless transmission / reception unit 2, and if the transmission error check passes the path, the control unit 1 responds to the received data (message M). For example, a notification sound is generated from the notification unit 5 to notify the occurrence of an event (fire occurrence, etc.).

  As described above, according to the present embodiment, if the timing at which the control unit 1 serving as the synchronization bit pattern detection unit detects the synchronization bit pattern Sync coincides with the cycle, the control unit 1 serving as the determination unit uses a normal radio signal. If it is determined that the timing does not match the cycle, the control unit 1 determines that the radio signal is not a normal radio signal, and if the control unit 1 determines that the signal is not a normal radio signal, the control unit 1 serving as a control unit serves as the reception unit. Since the radio transmission / reception unit 2 is stopped, it is possible to determine whether the received radio wave is a desired wave or an undesired wave depending on whether or not the synchronization bit pattern Sync is included. By stopping the wireless transmission / reception unit 2, useless consumption of the battery can be prevented.

  In the present embodiment, the data length of the synchronization bit pattern Sync is 1 byte and the period is 2 bytes, but the present invention is not limited to this. However, if the data length of the synchronization bit pattern Sync is 1 byte, there is an advantage that the process of inserting and detecting the synchronization bit pattern can be simplified. Further, if the data bits (Data) inserted with the synchronization bit pattern Sync are NRZ-encoded, the transmission efficiency of the radio signal can be improved. That is, in NRZ encoding, normally, parity bits are inserted so that 1 or 0 does not continue, but normal transmission using NRZ codes is possible because the synchronization bit pattern Sync plays the role of the parity bits.

  By the way, the unique word UW for establishing frame synchronization is set to a bit pattern that can be clearly distinguished from the preamble PA and other data bit examples (destination address DA, source address SA, message M, CRC code). However, it may be difficult to ensure uniqueness by inserting the synchronization bit pattern Sync. Therefore, as shown in FIG. 2B, the synchronization bit pattern Sync is not inserted into the unique word UW portion within one frame, and the synchronization bit pattern Sync is inserted only into the portion excluding the unique word UW (and the preamble PA). This makes it easy to ensure uniqueness of the unique word UW.

  Alternatively, as shown in FIG. 2C, a synchronization bit pattern XSync in which the order of 0 and 1 is exchanged with respect to the synchronization bit pattern Sync may be inserted only in the unique word UW portion in one frame. In this way, there is an advantage that it is easy to ensure the uniqueness of the unique word UW while determining whether or not the desired wave is in the unique word UW portion.

It is a system configuration figure showing an embodiment of the present invention. (A)-(c) is the data format of the radio signal in the same as the above. It is a flowchart for operation | movement description same as the above.

Explanation of symbols

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

Claims (7)

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.
The radio having the transmission means includes synchronization bit pattern insertion means for inserting a synchronization bit pattern in which 0 and 1 are alternately arranged in one frame of a radio signal at a predetermined period,
In the wireless device including the receiving means, the synchronization bit pattern detection means for detecting the synchronization bit pattern of the radio signal received by the reception means and the timing for detecting the synchronization bit pattern by the synchronization bit pattern detection means coincide with the cycle. If it is determined that the wireless signal is not a normal wireless signal and the determination means determines that the wireless signal is not a normal wireless signal if the timing does not match the cycle, the receiving means And a control means for stopping the transmission. The wireless device including the receiving unit includes a detecting unit that detects the intensity of the radio wave received by the receiving unit, and a comparing unit that compares the intensity of the radio wave detected by the detecting unit with a predetermined threshold value.
The control means of the radio device operates the synchronization bit pattern detection means if the radio wave intensity exceeds the threshold according to the comparison result of the comparison means, and operates the synchronization bit pattern detection means if the radio wave intensity does not exceed the threshold. 2. The wireless transmission system according to claim 1, wherein the receiving means is stopped without doing so.   3. The wireless transmission system according to claim 1, wherein the determining means determines whether or not the radio signal is normal during reception of the radio signal. The radio signal transmitted by the transmission means has a frame configuration including a unique word for establishing frame synchronization,
The radio transmission system according to any one of claims 1 to 3, wherein the synchronization bit pattern insertion means inserts the synchronization bit pattern into a portion excluding the unique word in one frame. The radio signal transmitted by the transmission means has a frame configuration including a unique word for establishing frame synchronization,
4. The synchronization bit pattern insertion unit inserts a synchronization bit pattern in which the order of 0 and 1 is changed only in a unique word portion in one frame. 5. Wireless transmission system.   6. The wireless transmission system according to claim 1, wherein the synchronization bit pattern insertion means sets the synchronization bit pattern to 1 byte length.   The wireless transmission system according to any one of claims 1 to 6, wherein the transmission means performs non-return-zero coding on information transmitted by a wireless signal.

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