JP6737113B2 - Communications system - Google Patents

Description

The present invention relates to communication systems such as remote monitoring systems.

There is known a remote monitoring system used for automatic meter reading of gas meters and water meters, or for monitoring fires and abnormal situations (see Patent Document 1). In these remote monitoring systems, for example, the center device transmits various request signals to the master device, and the master device transmits the request signal from the center device to each slave device accommodated by the master device, The slave unit is connected to the gas meter, the water meter or the sensor, wirelessly transmits the detection signal to the master unit in response to the request signal, and the master unit transmits the detection signal to the center device. The center device performs business such as issuing a bill for the usage amount based on the transmitted meter reading data.

In these remote monitoring systems, communication is performed between the center device and the base unit via a public line such as a mobile phone line, and communication is normally performed between the base unit and the handset by a specific low power radio. The specific low power radio has a small transmission power of about 10 mW and a communicable distance of about 100 m. Therefore, the communication between the slave unit and the master unit is not only directly connected but also relayed by another slave unit to the master unit. It is common to connect to.

JP-A-2007-274068

In the conventional remote monitoring system, since a public line is used between the center device and the master unit, the running cost such as communication cost increases as the number of master units increases. For this reason, for example, when a small village is far away, it is necessary to install a master unit for a small number of slave units, which causes a problem that cost efficiency is deteriorated.

The present invention has been made to solve such a problem, and an object of the present invention is to perform communication with a master unit using a public line and a plurality of master units each housing a plurality of slave units. In a communication system including a center device, it is possible to suppress the deterioration of cost-effectiveness caused by installing a master unit for a small number of slave units.

A communication system according to the present invention is a communication system including a plurality of master devices each accommodating a plurality of slave devices, and a center device that communicates with the master device using a public line. The master unit has a first wireless communication unit that wirelessly communicates with the slave unit, and a second wireless communication unit that wirelessly communicates with the master unit and that has a higher output than the first wireless communication unit. some of the plurality of the master unit, using the second wireless communication means, have lines communicating with the center apparatus via the base unit, a plurality of slave units housed in the master unit, the master machine Based on the electric field strength of the radio wave from, the remote unit is divided into a short-distance group and a long-distance group, and the child device of the long-distance group is not communicating with the parent device housing the child device. Only when, the communication system is characterized in that it can communicate with the master unit accommodating the slave unit .

According to the present invention, in a communication system including a plurality of masters each accommodating a plurality of slaves, and a center device that communicates with the master using a public line, a master for a small number of slaves is provided. It is possible to suppress the deterioration of cost-effectiveness caused by installing the machine.

It is a figure which shows the structure of the communication system which concerns on embodiment of this invention. It is a block diagram of a cordless handset in a communication system concerning an embodiment of the present invention. It is a block diagram of the main|base station in the communication system which concerns on embodiment of this invention. It is a block diagram of the center device in the communication system concerning an embodiment of the present invention. It is a figure which shows the flow at the time of installation of the 1st step|paragraph subunit|mobile_unit in the communication system which concerns on embodiment of this invention. FIG. 3 is a block diagram for explaining internal configurations and operations of a high output radio unit and a low output radio unit in FIG. 2. It is a figure which shows the flow at the time of communication between parent devices in the communication system which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Communication system configuration>
FIG. 1 is a diagram showing a configuration of a communication system according to an embodiment of the present invention.
This communication system is used, for example, in an automatic meter reading system for a gas meter or a water meter, and is a first master unit that is connected to the center apparatus 10 via a center apparatus 10 and a public line 20 such as a mobile telephone line. 30-1, a second master device 30-2 that wirelessly communicates with the first master device 30-1, and subordinate slave devices 40a to 40f housed in the first master device 30-1. Although not shown, the second parent device 30-2 also accommodates a plurality of child devices. In the following description, the first master unit 30-1 and the second master unit 30-2 are referred to as the master unit 30 when not distinguished from each other.

A meter reading device (meter or the like) is connected to the slaves 40a to 40f. The first parent device 30-1 manages the child devices 40a to 40f, receives meter reading data from the child devices 40a to 40f, and transmits the data to the center device 10 via the public line 20. In the following description, the slave units 40a to 40f are referred to as the slave unit 40 when they are not distinguished.

The first parent device 30-1 can communicate with the child devices 40a and 40d by the specific low power radio. In addition, the handset 40a can communicate with the handset 40b and the handset 40c by the specified low power radio, and the handset 40d can communicate with the handset 40e and the handset 40f by the specified low power radio. Further, the slave device 40 transmits the meter reading data to the center device 10 via the first master device 30-1, and by configuring the meter device in multiple stages (here, two stages), more meter reading data can be collected. It is possible.

The cordless handsets 40a to 40c form a short-distance group, and the cordless handsets 40d to 40f form a long-distance group. The short-distance group is a first-stage slave unit (a slave unit immediately below the master unit) in which the electric field strength of the radio wave from the master unit exceeds a predetermined threshold, and a slave unit group using the slave unit as a relay slave unit. The distance group is a first-stage slave unit in which the electric field strength of the radio wave from the master unit is equal to or lower than a predetermined threshold value, and a slave unit group including the slave unit as a relay slave unit.

<Structure of cordless handset>
FIG. 2 is a block diagram of a slave unit in the communication system according to the embodiment of the present invention.
As illustrated, the child device 40 includes a control unit 41, a transmission/reception unit 42 connected to the control unit 41, a storage unit 43, an I/F (interface) unit 44, a display unit 45, and an operation input unit 46. The transmitting/receiving unit 42 is connected to the antenna 47.

The control unit 41 includes a CPU, a RAM, and a ROM, and controls the entire child device 40 and performs arithmetic processing. That is, for example, a test signal is generated to determine a communicable master device 30 or slave device 40, and route information (terminal ID, electric field strength, etc.) for the determined master device 30 or slave device 40 is stored in the storage unit 43. Or to analyze a transmission message from another child device 40.

The transmission/reception unit 42 performs wireless communication with the other child device 40 and the parent device 30 by short-distance wireless communication. The storage unit 43 includes a non-volatile memory and stores various setting data and the like. External devices such as a gas meter and a water meter are connected to the I/F unit 44.

The display unit 45 is a user I/F configured by an LED or the like and displaying the operating state of the slave device 40. The operation input unit 46 includes a button, a switch, and the like, and is a user I/F for inputting a predetermined setting for the child device 40. The antenna 47 transmits and receives radio waves.

<Configuration of base unit>
FIG. 3 is a block diagram of a master unit in the communication system according to the embodiment of the present invention.
As illustrated, the parent device 30 includes a control unit 31, a storage unit 32 connected to the control unit 31, a high output wireless unit 33, a low output wireless unit 34, a network control unit 35, a display unit 36, and The operation input unit 37 is provided. Further, an antenna 38 and an antenna 39 are connected to the high output radio section 33 and the low output radio section 34, respectively.

The control unit 31 includes a CPU, a RAM, and a ROM, and controls the entire base unit 30 and performs arithmetic processing. That is, for example, based on the route information transmitted from the child device 40, the route information is newly registered or updated in the storage unit 32. The storage unit 32 is composed of a non-volatile memory, and stores data necessary for control and arithmetic processing by the control unit 31.

The high-power wireless unit 33 uses radio waves of 467 MHz and 5 W to perform wireless communication with another parent device 30. The communicable distance is 10 km. The low-power wireless unit 34 performs wireless communication with the child device 40 by short-range wireless communication of 429 MHz and 10 mW. The communicable distance is 100 m. Further, the low-power radio unit 34 receives a transmission signal from another master device 30. The network control unit 35 communicates with the center device 10 via the public line 20.

The display unit 36 is composed of an LED or the like, and displays the operating state of the parent device 30. The operation input unit 37 includes a button, a switch, and the like, and is a user I/F for inputting a predetermined setting for the master device 30. The antenna 38 and the antenna 39 transmit and receive radio waves.

<Center device configuration>
FIG. 4 is a block diagram of the center device in the communication system according to the embodiment of the present invention. As illustrated, the center device 10 includes a control unit 11, a network control unit 12, a storage unit 13, a display unit 14, and an operation input unit 15, which are connected to the control unit 11.

The control unit 11 includes a CPU, a RAM, and a ROM, and controls the center device 10 as a whole and performs arithmetic processing. That is, for example, the terminal IDs of the master device 30 and the slave device 40 are respectively registered, and the route information is newly registered or updated in the storage unit 13 based on the route information transmitted from the slave device 40.

<Flow when installing a handset>
FIG. 5 is a diagram showing a flow when the first-stage slave unit is installed in the communication system according to the embodiment of the present invention.

The installed child device 40 performs normal route search and installation processing (step S1). That is, a test signal in which the terminal ID (identification information) of itself is added to the broadcast message read from the storage unit 43 is transmitted, and if a response is received within a predetermined time, the response message is received and processed, and the electric field in the response message is received. Get strength and relay stage number information.

Next, the child device 40 determines whether or not the immediate upper terminal of the own terminal is the parent device based on the acquired relay stage number information (step S2). If the result of determination is that it is not the parent device (step S2: NO), the processing shown in this figure ends.

If the result of determination is that it is the parent device (step S2: YES), it is determined whether the electric field strength acquired in step S1 is less than or equal to a predetermined threshold value (step S3). As a result of the determination, if it is less than or equal to the threshold value (step S3: YES), the own terminal is set as a long-distance group (step S4), and if it exceeds the threshold value (step S3: NO), the own terminal is set near. The distance group is set (step S5). Then, the setting information is notified to the parent device (step S6), and the processing shown in this figure ends.

<High output radio section and low output radio section>
FIG. 6 is a block diagram for explaining internal configurations and operations of the high-power radio unit and the low-power radio unit in FIG.

The high-power radio unit 33 is a unit for transmitting a radio signal of 467 MHz to another parent device, and includes a modulation circuit 33a and a power amplification circuit 33b. The modulation circuit 33a outputs a 467 MHz modulated signal modulated by the electronic message generated by the control unit 31. The power amplification circuit 33b amplifies the modulation signal output from the modulation circuit 33a to 5 W, and the antenna 38 transmits the radio wave of the modulation signal output from the power amplification circuit 33b.

The low-power radio unit 34 is means for transmitting and receiving a radio signal of 429 MHz by a specific low power radio to and from another child device, and receiving a 467 MHz radio signal transmitted from another parent device, The switching circuit 34a, the switching circuit 34b, the switching circuit 34c, the modulation circuit 34d, the power amplification circuit 34e, the filter 34f, the filter 34g, the filter 34h, the filter 34i, the LNA (low noise amplification circuit) 34j, and the demodulation circuit 34k are provided. ..

The switching circuit 34a switches between transmission and reception of a signal with respect to the antenna 39. When the switching circuit 34a is set to the receiving side, the switching circuit 34b and the switching circuit 34c connect the receiving circuit to a first processing path that passes through one filter 34i, and three cascade-connected filters 34f and 34g. , And the second processing path passing through the filter 34h.

Here, the four filters are bandpass filters having the same parameters, and the parameters are set so that the attenuation of the input signal of 429 MHz is about 0 dB for each filter and the attenuation of the input signal of 467 MHz is 20 dB. ing.

When the switching circuit 34a is set to the transmission side, the modulation circuit 34d outputs a 429 MHz modulated signal that is modulated by the telegram for communication between the master unit and the slave unit generated by the control unit 31. The power amplification circuit 34e amplifies the modulation signal output from the modulation circuit 34d to 10 mW. The modulated signal output from the power amplification circuit 34e passes through the switching circuit 34a and is transmitted as a radio wave from the antenna 39.

When the switching circuit 34a is set to the receiving side and the switching circuit 34b and the switching circuit 34c are set to the first processing path, the reception signal at the antenna 39 is the switching circuit 34b, the filter 34i, and the switching circuit. It is input to LNA 34j through 34c.

When the switching circuit 34a is set to the receiving side and the switching circuit 34b and the switching circuit 34c are set to the second processing path, the reception signal at the antenna 39 is the switching circuit 34b, the filter 34f, and the filter 34g. , The filter 34h, and the switching circuit 34c to be input to the LNA 34j.

The LNA 34j amplifies the input signal and outputs it to the demodulation circuit 34k. The demodulation circuit 34k takes out the electronic message from the received signal and sends it to the control unit 31.

<Flow of communication between base units>
FIG. 7 is a diagram showing a flow at the time of communication between parent devices in the communication system according to the embodiment of the present invention. Here, a case where the first master device 30-1 performs inter-master device communication with the second master device 30-2 according to an instruction from the center device 10 will be described.

The control unit 31 of the first parent device 30-1 sets the receiving circuit of the low-power radio unit 34 as the default on the first processing route, that is, the route passing through the filter 34i (step S11). Next, the control unit 31 determines whether or not there is a transmission instruction from the center device 10 to the high output wireless unit 33 (step S12).

If the result of determination is that there is not any (step S12: NO), the processing shown in this figure ends. If the result of the determination is that there is (step S12: YES), from the low-power wireless unit 34, of the slave units in the long-distance group, the slave unit 40d, which is the slave unit immediately below, receives the specific low-power radio of 429 MHz. A transmission prohibition signal is transmitted by radio waves (step S13).

The slave device 40d that has received the transmission prohibition signal does not transmit to the first master device 30-1. Note that the short-distance group child device 40a can perform transmission to the first parent device 30-1.

Next, the control unit 31 of the first parent device 30-1 switches the receiving circuit of the low-power radio unit 34 to the second processing route, that is, the route passing through the filters 34f, 34g, and 34h (step S14).

Next, the first master device 30-1 starts communication between the master devices using the high-power wireless unit 33 and the second master device 30-2 by using a radio signal of 467 MHz (step S15). ). By this communication between the master units, the second master unit 30-2 can transmit the meter reading data transmitted from the slave unit under the control to the first master unit 30-1.

The radio wave of 467 MHz transmitted from the second parent device 30-2 passes through the antenna 39, the switching circuit 34a, the switching circuit 34b, the filter 34f, the filter 34g, the filter 34h, and the switching circuit 34c, and is input to the LNA 34j. Then, it is amplified by the LNA 34 j, the telegram is extracted by the demodulation circuit 34 k, and sent to the control unit 31.

At this time, the reception signal of 467 MHz received by the antenna 39 is attenuated by 60 dB by passing through the filters 34f, 34g and 34h. However, since the level of the received signal is high, it is possible to demodulate the electronic message in the received signal by amplifying it with the LNA 34j.

When a signal is transmitted from the child device 40a of the short-distance group during the communication between the parent devices, the same route as the signal transmitted from the second parent device 30-2, that is, the switching circuit 34a, the switching circuit 34b, and the filter 34f. , The filter 34g, the filter 34h, and the switching circuit 34c, and is input to the LNA 34j. Since the electric field strength of the signal from the slave unit 40a exceeds a predetermined threshold value, even if there is some loss (attenuation) by passing through the filter 34f, the filter 34g, and the filter 34h, the demodulation of the telegram in the received signal is performed. Is possible.

Next, the first master device 30-1 monitors the end of the communication between the master devices (step S16), and if it is determined that the communication between the master devices is completed (step 16: YES), the low output wireless unit 34 receives the signal. The circuit is switched to the first processing path, that is, the path passing through the filter 34i (step S17).

Next, the first parent device 30-1 transmits a transmission permission signal from the low-power wireless unit 34 to the child device 40d that is the child device immediately below among the child devices in the long-distance group (step S18). .. The slave device 40d that has received the transmission permission signal can perform transmission to the first master device 30-1.

When the child device 40d transmits a signal, the signal is input to the LNA 34j through the antenna 39, the switching circuit 34a, the switching circuit 34b, the filter 34i, and the switching circuit 34c. Although the signal from the slave unit 40d has the electric field strength equal to or lower than a predetermined threshold value but does not pass through the first processing path that passes through the three filters but the second processing path that passes through one filter, the loss ( Attenuation) becomes small, and the telegram in the signal can be demodulated.

At this time, the child device 40a in the long distance group can also transmit a signal to the first parent device 30-1. When the child device 40a transmits a signal, the signal is input to the LNA 34j through the antenna 39, the switching circuit 34a, the switching circuit 34b, the filter 34i, and the switching circuit 34c. Although the received electric field strength of the signal from the child device 40a exceeds a predetermined threshold value, the LNA 34j operates without being saturated, so that the telegram in the signal can be demodulated.

The following flow (1) to (3) can be summarized as the flow of communication between the master units described above.
(1) 429 MHz transmission and reception are not performed at the same time, and the switching circuit 34a switches between transmission and reception.
(2) During transmission of 467 MHz (during communication between master devices), the switching circuit 34a is switched to the receiving side, and the switching circuits 34b and 34c are switched to the first processing path. At this time, it is possible to receive and demodulate the 467 MHz signal transmitted from the second parent device 30-2 and to receive and demodulate the 429 MHz signal transmitted from the short-distance group child device 40a.
(3) When not transmitting 467 MHz, the switching circuits 34b and 34c are switched to the second processing path. At this time, it is possible to receive and demodulate the 429 MHz signal transmitted from the child device 40a in the short distance group and the 429 MHz signal transmitted from the child device 40d in the long distance group.

<Modified flow of communication between base units>
In the flow shown in FIG. 7, during steps S13 to S17, that is, while transmission from the remote device 40d in the long distance group to the first master device 30-1 is prohibited, the remote device 40d or 40e in the long distance group is performed. Alternatively, even if the sensor connected to 40f detects an emergency such as a gas leak or a low battery level, it cannot be notified to the center device 10.

Therefore, when such an emergency is detected, the child device 40d of the long-distance group notifies the first parent device 30-1 via the child device 40a of the short-distance group to notify the emergency situation. Enable notification of.

It is needless to say that the number of parent devices, the number of child devices, and the frequency of radio waves in the above-described embodiments are examples, and may be numbers other than those in the embodiments.
That is, for example, in FIG. 1, it is possible to add one or more master devices that perform inter-master communication with the first master device 30-1. It is also possible to add one or more master devices that communicate with the first master device 30-1 via the second master device 30-2.

10... Center device, 20... Public line, 30... Master, 30-1... First master, 30-2... Second master, 33... High output radio section, 34... Low output radio section, 34f ~34i ... filter, 40, 40a to 40f ... slave unit.

Claims (3)

A communication system comprising a plurality of parent devices each accommodating a plurality of child devices, and a center device that communicates with the parent device using a public line,
The plurality of parent devices include a first wireless communication unit that wirelessly communicates with the child device and a second wireless communication unit that wirelessly communicates with the parent device and that has a higher output than the first wireless communication unit. Have,
Some of the plurality of the master unit, using the second wireless communication means, have lines communicating with the center apparatus via the base unit,
The plurality of child devices housed in the parent device are divided into a short-distance group and a long-distance group based on the electric field strength of the radio wave from the parent device, and the child devices of the long-distance group A communication system characterized in that it is possible to communicate with a master unit that accommodates the slave unit only when the master unit that accommodates the slave unit is not communicating with the master unit . In the communication system according to claim 1 ,
The child device of the short-distance group can communicate with the parent device housing the child device regardless of whether the parent device housing the child device communicates with the parent device. A communication system characterized by. In the communication system according to claim 1 or 2 ,
The receiving unit of the first wireless communication means includes a first processing path that passes through a plurality of predetermined filters and a second processing path that passes through a number of filters smaller than the predetermined plurality of filters.
When starting transmission by the second wireless communication unit, the master unit switches the receiving unit of the first wireless communication unit to the first processing path, and causes the first wireless communication unit to perform the remote communication. A communication system, wherein a transmission prohibition signal is transmitted to a child device of a distance group.

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