Radio wave measuring device

Abstract

To provide a radio-wave measurement device capable of changing a priority order of selection conditions.SOLUTION: A radio-wave measurement device 60 selects one of a plurality of first wireless communication terminals 20 as a communication counterpart of a second wireless communication terminal 20A. The radio-wave measurement device 60 includes a processing unit 61. The processing unit 61 selects the one of the plurality of first wireless communication terminals 20 as the communication counterpart of the second wireless communication terminal 20A based on a plurality of selection conditions F. The processing unit 61 performs determination processing which determines whether or not to change a priority order set in each of the plurality of selection conditions F. The processing unit 61 changes the priority order when a determination is made to change the priority order. The processing unit 61 performs condition selection processing to select one of the plurality of selection conditions F according to the priority order, and terminal selection processing to select a wireless communication terminal 20 matching the selected selection condition from the plurality of first wireless communication terminals 20.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a radio wave measuring device. [Background technology]

[0002] A new wireless communication terminal may be added to a communication system having a plurality of wireless communication terminals. In this case, a process is required to select a communication partner of the wireless communication terminal to be added from among the wireless communication terminals already installed (for example, see Patent Document 1).

[0003] In the wireless communication system of Patent Document 1, when determining a communication partner of a newly installed handset, the newly installed handset broadcasts a call request to surrounding terminals multiple times. The newly installed handset determines the priority of the communication partner based on the sum or average of the uplink field strength values ​​from among the terminals that have transmitted call responses including a reception field strength value (reception field strength value of the call request: uplink field strength value) that allows good communication in response to all the multiple broadcasts. When there are multiple terminals with the same sum or average of the uplink field strength values, the newly installed handset determines the priority of the communication partner based on the difference between the reception field strength (uplink field strength value) included in the multiple call responses. Furthermore, when there are multiple terminals with the same difference in the uplink field strength values, the newly installed handset determines the priority of the communication partner based on the difference between the reception field strength value (downlink field strength value) of the call response received by the newly installed handset and the uplink field strength value for each time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-193064 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the wireless communication system of Patent Document 1, the priority of selection conditions, which are conditions for selecting a communication partner, is fixed. Specifically, the first priority is the sum or average value of the uplink electric field strength values. The second priority is the difference between the uplink electric field strength values. The third priority is the difference between the downlink electric field strength value and the uplink electric field strength value. As a result, in the wireless communication system of Patent Document 1, for example, it is not possible to change the priority of the selection conditions depending on the on-site environment, and there is a risk that a communication partner suitable for the on-site environment cannot be selected.

[0006] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a radio wave measuring device that can change the priority order of selection conditions. [Means for solving the problem]

[0007] A radio wave measuring device of the present invention selects one of a plurality of first wireless communication terminals as a communication partner of a second wireless communication terminal. The radio wave measuring device includes a processing unit. The processing unit selects one of the plurality of first wireless communication terminals as a communication partner of the second wireless communication terminal based on a plurality of selection conditions. The processing unit executes a decision process for deciding whether or not to change a priority order set for each of the plurality of selection conditions. When the processing unit decides to change the priority order, it changes the priority order. The processing unit executes a condition selection process for selecting one of the plurality of selection conditions according to the priority order, and a terminal selection process for selecting a wireless communication terminal that matches the selected selection condition from among the plurality of first wireless communication terminals. Effect of the Invention

[0008] According to the radio wave measuring device of the present invention, the priority order of the selection conditions can be changed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 illustrates a communication system. [Diagram 2] FIG. 1 illustrates a communication system. [Diagram 3] FIG. 1 illustrates a communication system. [Figure 4] 1 is a block diagram showing a configuration of a radio wave measurement terminal according to a first embodiment of the present invention. [Diagram 5] FIG. 13 is a diagram showing a plurality of selection conditions. [Figure 6] FIG. 13 is a diagram showing a priority order previously set for each of a plurality of selection conditions. [Figure 7] FIG. 13 is a diagram showing an example of priorities after being changed based on a priority change instruction by a worker. [Figure 8] 11A and 11B are diagrams illustrating an example of an average field strength value and a packet acquisition rate measured by a processing unit of a radio wave measurement terminal. [Figure 9] 11 is a diagram showing the maximum fluctuation range of the average electric field strength measured by a processing unit of the radio wave measurement terminal. FIG. [Figure 10] 11A and 11B are diagrams illustrating an example of an average field strength, a minimum field strength, and a packet acquisition rate measured by a processing unit of a radio wave measurement terminal. [Figure 11] 11 is a diagram showing the maximum difference between the average field strength and the minimum field strength measured by a processing unit of a radio wave measurement terminal. FIG. [Figure 12] FIG. 2 is a block diagram showing the configuration of a slave unit. [Figure 13] FIG. 1 illustrates a communication system. [Figure 14] 13 is a flowchart showing a process executed by a processing unit of the radio wave measurement terminal. [Figure 15] 13 is a flowchart showing a process executed by a processing unit of the radio wave measurement terminal. [Figure 16] 13 is a flowchart showing a process executed by a processing unit of the radio wave measurement terminal. [Figure 17] 13 is a flowchart showing a process executed by a processing unit of the radio wave measurement terminal. [Figure 18] 13 is a flowchart showing a process executed by a processing unit of the radio wave measurement terminal. [Figure 19] FIG. 11 is a sequence diagram showing an example of a process executed by a radio wave measurement terminal. [Figure 20]FIG. 2 is a diagram showing the configuration of an operation unit of a radio wave measurement terminal. [Figure 21] 13 is a diagram showing a first input screen displayed on a display unit of the radio wave measurement terminal. FIG. [Figure 22] 13 is a diagram showing a second input screen displayed on the display unit of the radio wave measurement terminal. FIG. [Diagram 23] FIG. 13 is a diagram showing a modified example of the second input screen. [Figure 24] 10 is a flowchart showing a process executed by a processing unit of a radio wave measurement terminal according to a second embodiment of the present invention. [Diagram 25] 10 is a flowchart showing a determination process executed by a processing unit of the radio wave measurement terminal. [Figure 26] 13 is a flowchart showing a modified example of the determination process executed by the processing unit of the radio wave measurement terminal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the radio wave measuring device of the present invention will be described with reference to the drawings (FIGS. 1 to 26). However, the present invention is not limited to the following embodiment, and can be implemented in various aspects without departing from the gist of the present invention. Note that where explanations are repeated, they may be omitted as appropriate. Also, in the drawings, the same or corresponding parts are denoted by the same reference symbols, and explanations will not be repeated.

[0011] [Embodiment 1] Hereinafter, a first embodiment of the present invention will be described with reference to Fig. 1 to Fig. 23. First, a communication system 100 will be described with reference to Fig. 1 and Fig. 2. Fig. 1 and Fig. 2 are diagrams showing the communication system 100. In detail, Fig. 1 and Fig. 2 each show a part of the communication system 100.

[0012] The communication system 100 includes a plurality of wireless communication terminals. The plurality of wireless communication terminals perform wireless communication based on predefined matching information. The matching information specifies a combination of the plurality of wireless communication terminals that communicate with each other. In detail, each wireless communication terminal stores, as matching information, information indicating a communication partner of the wireless communication terminal. In this embodiment, the communication system 100 is a telemetry system. Hereinafter, the communication system 100 may be referred to as a "telemetry system 100."

[0013] 1 and 2, the telemetry system 100 includes a master unit 10, a plurality of slave units 20, a server 40, and a center-side network control device 50. The master unit 10 and the slave units 20 are examples of wireless communication terminals.

[0014] 2, the telemetry system 100 further includes a plurality of meters 30. The meter 30 is a measuring device. The measurement target of the meter 30 is, for example, a resource or energy such as gas, water, or electricity. The meter 30 measures, for example, the amount of gas, water, or electricity used, and outputs a signal indicating a measurement value (a measured value).

[0015] The telemeter system 100 is a system that collects the results of measurements (measured values) by the meters 30. Specifically, the results of measurements by the meters 30 are collected by a server 40. The telemeter system 100 will be further described below with reference to Figs. 1 and 2.

[0016] As shown in FIG. 2, in this embodiment, the multiple meters 30 include a meter 30a connected to the master unit 10 and multiple meters 30b connected to the multiple slave units 20, respectively.

[0017] The meter 30a is wired connected to the parent unit 10 via an electric wire PL. The electric wire PL has a signal line and a ground line. The parent unit 10 obtains a measurement value (measurement result) from the meter 30a. Similarly, the meters 30b are wired connected to the corresponding child units 20 via an electric wire PL. Each child unit 20 obtains a measurement value (measurement result) from the corresponding meter 30b.

[0018] Although the meter 30 (meter 30b) is omitted in FIG. 1 for ease of understanding, the telemeter system 100 includes the meter 30 (meter 30b) connected to each slave unit 20 shown in FIG.

[0019] The parent device 10 and the multiple child devices 20 perform wireless communication based on predefined adoption information. The adoption information defines a combination of communication partners (wireless communication terminals) with which the parent device 10 and the multiple child devices 20 communicate with each other. Therefore, the communication partners of the parent device 10 and each child device 20 are determined in advance. In detail, the parent device 10 and each of the multiple child devices 20 store, as the adoption information, identification information indicating the communication partner of the parent device. The identification information includes, for example, an identification ID of the communication partner and address information of the communication partner.

[0020] Specifically, in the telemeter system 100 shown in Figs. 1 and 2, the multiple slave units 20 include eleven slave units 20a to 20k. As shown in Fig. 1, the master unit 10 performs wireless communication with the slave units 20a and 20b. The slave unit 20a performs wireless communication with the master unit 10 and the slave unit 20c. The slave unit 20b performs wireless communication with the master unit 10, the slave unit 20d, and the slave unit 20f. The slave unit 20c performs wireless communication with the slave units 20a and 20e. The slave unit 20d performs wireless communication with the slave units 20b and 20g. The slave unit 20e performs wireless communication with the slave units 20c and 20h. The slave unit 20f performs wireless communication with the slave units 20b, 20i, and 20j. The slave unit 20g performs wireless communication with the slave units 20d and 20k. The child device 20h performs wireless communication with the child device 20e. The child device 20i performs wireless communication with the child device 20f. The child device 20j performs wireless communication with the child device 20f. The child device 20k performs wireless communication with the child device 20g. The parent device 10 and the multiple child devices 20 are connected in multiple stages in this manner. The parent device 10 is a wireless communication terminal in the 0th stage. For example, the child devices 20a and 20b are wireless communication terminals in the 1st stage.

[0021] In the telemeter system 100, communication between the master unit 10 and the slave unit 20, and communication between the slave units 20, for example, is performed using specific low power radio (special low power radio). The frequency band for communication using the special low power radio is, for example, the 920 MHz band. Hereinafter, communication using the special low power radio may be referred to as "special low power radio communication."

[0022] Each slave unit 20 transmits data indicating a measurement value acquired from the corresponding meter 30b (hereinafter, data indicating a measurement value may be referred to as "measurement data") to the master unit 10. Specifically, the slave units 20a and 20b communicate directly with the master unit 10. Thus, the slave units 20a and 20b transmit the measurement data directly to the master unit 10. The slave units 20c to 20k each communicate with the master unit 10 using the other slave units 20 as relay terminals. For example, the slave unit 20i transmits the measurement data to the master unit 10 using the slave units 20f and 20b as relay terminals (see FIG. 1).

[0023] 2, the master unit 10 performs wireless communication with the center-side network control device 50 via a wide area wireless network Ne. The master unit 10 transmits measurement data transmitted from each slave unit 20 to the center-side network control device 50 via the wide area wireless network Ne. The master unit 10 also transmits data indicating a measurement value acquired from the meter 30a (measurement data) to the center-side network control device 50 via the wide area wireless network Ne.

[0024] The wide area wireless network Ne is, for example, a PHS (Personal Handy-phone System) network, a FOMA (Freedom Of Mobile Multimedia Access) network, an LTE (Long Term Evolution) network, a 4G (Fourth Generation Mobile Communication System) network, or a 5G (Fifth Generation Mobile Communication System) network.

[0025] The center-side network control device 50 is provided, for example, in a public network of a telecommunications carrier. The center-side network control device 50 mediates communication between the server 40 and the host unit 10. The center-side network control device 50 transmits measurement data received from the host unit 10 to the server 40 via the wide area wireless network Ne.

[0026] The server 40 stores the measurement data transmitted from the center-side network control device 50 to the server 40 for each meter 30. For example, if the meter 30 is a gas meter, the server 40 is a server managed by a business entity that supplies gas.

[0027] 1 and 3, a description will be given of the work performed by an operator when adding a new slave unit 20A to the telemetry system 100. When adding a new slave unit 20A to the telemetry system 100, the operator uses the radio wave measurement terminal 60 to select one of the already installed slave units 20 as a communication partner for the slave unit 20A to be added. The radio wave measurement terminal 60 is an example of a radio wave measurement device.

[0028] Hereinafter, the slave unit 20 to be added may be referred to as a "newly installed slave unit 20A." The newly installed slave unit 20A is an example of a second wireless communication terminal. In this embodiment, the newly installed slave unit 20A communicates with the master unit 10 using one of the slave units 20 already installed as a relay terminal. The master unit 10 is an example of a third wireless communication terminal.

[0029] As shown in Fig. 1, the worker first emits radio waves from the radio wave measurement terminal 60 at the planned installation location PA of the new slave unit 20A. More specifically, the radio wave measurement terminal 60 broadcasts a first response request signal (wireless signal). The radio waves emitted from the radio wave measurement terminal 60 are an example of a first radio wave.

[0030] In this embodiment, the first response request signal requests relay stage information from the child device 20. The relay stage information is information indicating the stage number of the wireless communication terminal from the parent device 10. For example, the child device 20c and the child device 20d are wireless communication terminals at the second stage from the parent device 10.

[0031] Following the first response request signal, the radio wave measurement terminal 60 may transmit second or subsequent response request signals. In other words, the radio wave measurement terminal 60 may emit radio waves multiple times. Hereinafter, when there is no need to distinguish between the first response request signal and the second or subsequent response request signals, the first response request signal and the second or subsequent response request signals may be referred to as "response request signals." The response request signal includes identification information for identifying the radio wave measurement terminal 60.

[0032] The response request signal is received by the slave unit 20 installed within the communication distance of the radio wave measurement terminal 60. For example, the communication distance of the special low-power radio communication is 1 m or more and 1000 m or less. The communication distance of the radio wave measurement terminal 60 is equal to the communication distance of the newly installed slave unit 20A.

[0033] Fig. 3 is a diagram showing a communication system 100 (telemetry system 100). In detail, Fig. 3 shows a state in which response signals (wireless signals) addressed to a radio wave measurement terminal 60 are transmitted from slave units 20h, 20i, 20f, 20j, and 20k. Slave units 20h, 20i, 20f, 20j, and 20k are an example of a plurality of first wireless communication terminals.

[0034] 3, in this embodiment, slave units 20h, 20i, 20f, 20j, and 20k are installed within the communication distance range of radio wave measurement terminal 60. Therefore, the first response request signal is received by slave units 20h, 20i, 20f, 20j, and 20k.

[0035] Each of the slave units 20h, 20i, 20f, 20j, and 20k that have received the first response request signal transmits a response signal addressed to the radio wave measurement terminal 60. Specifically, each of the slave units 20h, 20i, 20f, 20j, and 20k emits radio waves. The radio waves emitted from the slave units 20h, 20i, 20f, 20j, and 20k are an example of second radio waves. Each of the radio waves carries a response addressed to the radio wave measurement terminal 60.

[0036] While the first response request signal is a broadcast signal, the second and subsequent response request signals are signals for which a destination is specified. The second and subsequent response request signals may be received by all or some of the slave units 20h, 20i, 20f, 20j, and 20k. Hereinafter, when there is no need to distinguish between a response signal to the first response request signal and a response signal to the second and subsequent response request signals, the response signal to the first response request signal and the response signal to the second and subsequent response request signals may be referred to as a "response signal."

[0037] The response signal (response) transmitted from the slave unit 20h includes identification information for identifying the slave unit 20h. Similarly, the response signals (responses) transmitted from the slave units 20i, 20f, 20j, and 20k include identification information for identifying the slave units 20i, 20f, 20j, and 20k, respectively. In this embodiment, the response signal to the first response request signal further includes relay number information.

[0038] When the radio wave measurement terminal 60 receives the response signal (radio wave), it selects one of the slaves 20h, 20i, 20f, 20j, and 20k as a communication partner of the newly installed slave device 20A based on a plurality of selection conditions F. For example, when the slave device 20h is selected as a communication partner of the newly installed slave device 20A, the newly installed slave device 20A communicates with the master device 10 using the slave devices 20h, 20e, 20c, and 20a as relay terminals.

[0039] In the following description, a slave unit 20 that transmits a response signal in response to a first response request signal may be referred to as a "response terminal 20." In this embodiment, the response terminals 20 include slave units 20h, 20i, 20f, 20j, and 20k.

[0040] Next, the configuration of the radio wave measurement terminal 60 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing the configuration of the radio wave measurement terminal 60 of this embodiment. As shown in Fig. 4, the radio wave measurement terminal 60 includes a processing unit 61, a wireless communication unit 62, a storage unit 63, an operation unit 64, and a display unit 65.

[0041] The processing unit 61 controls each element of the radio wave measurement terminal 60. For example, the processing unit 61 controls the wireless communication unit 62, the storage unit 63, and the display unit 65. The processing unit 61 includes a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The processor controls each element of the radio wave measurement terminal 60 by executing a computer program stored in the storage unit 63. The processing unit 61 and the storage unit 63 may form a microcomputer.

[0042] The wireless communication unit 62 performs wireless communication. Specifically, the wireless communication unit 62 transmits and receives radio waves (wireless signals). More specifically, the wireless communication unit 62 transmits a response request signal and receives a response signal. The processing unit 61 acquires identification information of the response terminal 20 from the response signal received by the wireless communication unit 62. The processing unit 61 further acquires relay number information from the response signal to the first response request signal. The wireless communication unit 62 has a wireless communication circuit unit 621 and an antenna 622.

[0043] The wireless communication circuit unit 621 converts the signal output from the processing unit 61 to the wireless communication circuit unit 621 into a signal conforming to a predetermined wireless communication method and transmits the signal to the antenna 622. As a result, radio waves (wireless signals) conforming to the predetermined wireless communication method are emitted from the antenna 622. The wireless communication circuit unit 621 converts the radio signals (radio waves) received by the antenna 622 into signals that can be processed by the processing unit 61 and outputs the signals to the processing unit 61. The wireless communication circuit unit 621 is, for example, a communication module having an RF-LSI for 920 MHz band communication.

[0044] The wireless communication circuit unit 621 detects the value of the electric field strength of the radio waves received by the antenna 622. The wireless communication circuit unit 621 outputs the detected value of the electric field strength to the processing unit 61. The processing unit 61 detects the electric field strength value for each response signal received by the antenna 622.

[0045] The storage unit 63 stores identification information of the radio wave measurement terminal 60 and various computer programs executed by the processing unit 61 (processor). The storage unit 63 further stores a plurality of selection conditions F. The plurality of selection conditions F indicate conditions for selecting a communication partner of the newly installed slave unit 20A. The storage unit 63 includes, for example, a semiconductor memory such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a flash memory.

[0046] The operation unit 64 is operated by an operator. By operating the operation unit 64, the operator can cause the radio wave measurement terminal 60 to transmit a first response request signal. In this embodiment, the operator can further operate the operation unit 64 to change the priority set for each of the multiple selection conditions F. In other words, the operator can instruct the processing unit 61 to change the priority of the selection conditions F. The operation unit 64 is an example of a reception unit. The operation unit 64 includes, for example, multiple hard keys. Hereinafter, an instruction to change the priority of the selection conditions F may be referred to as a "priority change instruction."

[0047] The display unit 65 displays various screens. The display unit 65 is, for example, a display device such as a liquid crystal display device or an organic EL (electroluminescence) display device. When one of the response terminals 20 is selected as a communication partner of the newly-installed slave unit 20A, the display unit 65 displays information for identifying the slave unit 20 selected as the communication partner of the newly-installed slave unit 20A.

[0048] In this embodiment, the display unit 65 displays an input screen. The worker can input (register or set) various pieces of information in input fields on the input screen by operating the operation unit 64. Specifically, the display unit 65 displays an input screen for inputting a priority change instruction.

[0049] The operation unit 64 may include a touch sensor. The touch sensor is superimposed on the display surface of the display unit 65 and generates a signal indicating a touch operation on the display surface by the worker. The worker can input various instructions to the processing unit 61 by the touch operation.

[0050] Next, the processing executed by the processing unit 61 of the radio wave measurement terminal 60 will be described with reference to Fig. 4. The processing unit 61 selects one of the response terminals 20 as a communication partner of the newly-installed slave terminal 20A based on a plurality of selection conditions F. In this embodiment, as described with reference to Figs. 1 and 3, the processing unit 61 selects one of the slave terminals 20h, 20i, 20f, 20j, and 20k as a communication partner of the newly-installed slave terminal 20A.

[0051] More specifically, the processing unit 61 executes a determination process. The determination process is a process for determining whether or not to change the priority order set for each of the multiple selection conditions F. When the processing unit 61 determines to change the priority order for the selection conditions F, the processing unit 61 changes the priority order set for each of the multiple selection conditions F.

[0052] In this embodiment, the processing unit 61 determines whether to change the priority of the selection conditions F depending on whether the operation unit 64 has accepted a priority change instruction. When the processing unit 61 determines to change the priority of the selection conditions F, the processing unit 61 changes the priority set for each of the multiple selection conditions F based on the priority change instruction.

[0053] The processing unit 61 further executes a condition selection process and a terminal selection process. The condition selection process is a process of selecting one of a plurality of selection conditions F according to the priority order set for each of the plurality of selection conditions F. The terminal selection process is a process of selecting a response terminal 20 that matches the selected selection condition F. More specifically, the processing unit 61 repeats the condition selection process and the terminal selection process until one of the response terminals 20 is selected as a communication partner of the newly-installed handset 20A. For example, when a plurality of response terminals 20 are selected by the first terminal selection process, the processing unit 61 executes a second condition selection process and a second terminal selection process. Hereinafter, the response terminal 20 selected by the previously executed terminal selection process may be referred to as the "remaining response terminal 20".

[0054] Next, the multiple selection conditions F will be described with reference to Figures 1, 3, 4, and 5. Figure 5 is a diagram showing the multiple selection conditions F. The multiple selection conditions F include selection conditions F1 to F7. Selection condition F1 is an example of a first selection condition, and selection conditions F6 to F7 are examples of second selection conditions.

[0055] <Selection condition F1> The selection condition F1 specifies that a response terminal 20 having a field strength value equal to or greater than a first reference value Q1 is to be selected. Here, the field strength value indicates the value of the field strength of the radio wave received from the response terminal 20 by the wireless communication unit 62 of the radio wave measurement terminal 60.

[0056] In this embodiment, the selection condition F1 always has the first priority. The processing unit 61 executes a terminal selection process based on the selection condition F1 to select, from among the response terminals 20, a response terminal 20 whose field strength value is equal to or greater than a first reference value Q1.

[0057] <Selection condition F2> Selection condition F2 specifies that a response terminal 20 with the fewest number of relay steps is selected. As described with reference to Figs. 1 and 3, the number of relay steps indicates the number of steps from the parent device 10 at which a wireless communication terminal is located. As shown in Fig. 1, child device 20h and child device 20k are wireless communication terminals in the fourth step. Child device 20i and child device 20j are wireless communication terminals in the third step. Child device 20f is a wireless communication terminal in the second step. Processing unit 61 executes a terminal selection process based on selection condition F2 to select a response terminal 20 with the fewest number of relay steps from among the remaining response terminals 20.

[0058] The number of relay stages corresponds to the number of relay terminals. Specifically, the number of relay terminals indicates the number of wireless communication terminals that are present as relay terminals between the parent device 10 and the newly-installed child device 20A. For example, when the child device 20h, which is a wireless communication terminal in the fourth stage, is selected as the communication partner of the newly-installed child device 20A, the number of relay terminals is four. Therefore, the selection condition F2 corresponds to a selection condition that specifies that the response terminal 20 with the fewest number of relay terminals is selected.

[0059] <Selection condition F3> Selection condition F3 specifies that the response terminal 20 having the fewest number of subordinate slaves is to be selected. Here, the subordinate slaves refer to slaves 20 (wireless communication terminals) that communicate with the parent device 10 via the response terminal 20 as a relay terminal.

[0060] As shown in Fig. 1, the subordinate slaves of slave 20f are slave 20i and slave 20j. Therefore, the number of subordinate slaves of slave 20f is two. On the other hand, the number of subordinate slaves of each of slaves 20h, 20i, 20j, and 20k is zero. The processing unit 61 executes a terminal selection process based on selection condition F3 to select the response terminal 20 with the fewest number of subordinate slaves from among the remaining response terminals 20. The number of subordinate slaves is an example of the number of subordinate terminals.

[0061] <Selection condition F4> Selection condition F4 specifies that the response terminal 20 with the most stable field strength should be selected. Here, the field strength value indicates the value of the field strength of the radio wave received from the response terminal 20 by the wireless communication unit 62 of the radio wave measurement terminal 60. The processing unit 61 executes a terminal selection process based on selection condition F4 to select the response terminal 20 with the most stable field strength from among the remaining response terminals 20.

[0062] <Selection condition F5> Selection condition F5 specifies that the response terminal 20 having the highest packet acquisition rate P is selected. The packet acquisition rate P indicates the number of packets received by the wireless communication unit 62 out of a predetermined number of packets. The processing unit 61 executes a terminal selection process based on the selection condition F5 to select the response terminal 20 having the highest packet acquisition rate P from among the remaining response terminals 20.

[0063] More specifically, the second and subsequent response request signals include response request signals requesting the remaining response terminals 20 to transmit a predetermined number of packets. The response terminal 20 requested to transmit packets transmits a response signal carrying a predetermined number of packets. As a result, the wireless communication unit 62 of the radio wave measurement terminal 60 receives the packets. The processing unit 61 obtains the number of packets received by the wireless communication unit 62 and calculates a packet acquisition rate P.

[0064] <Selection condition F6> Selection condition F6 specifies that a response terminal 20 with a peripheral terminal count equal to or greater than a second reference value Q2 is to be selected. Peripheral terminals refer to child devices 20 (wireless communication terminals) capable of communicating with the response terminal 20. Child devices 20 (peripheral terminals) capable of communicating with the response terminal 20 include child devices subordinate to the response terminal 20. Child devices 20 capable of communicating with the response terminal 20 may include child devices subordinate to the response terminal 20 and child devices 20 other than child devices subordinate to the response terminal 20.

[0065] The processing unit 61 executes a terminal selection process based on the selection condition F6 to select a response terminal 20 having a number of peripheral terminals equal to or greater than the second reference value Q2 from among the remaining response terminals 20. The terminal selection process based on the selection condition F6 makes it possible to select a slave unit 20 having a large number of peripheral terminals as a communication partner of the newly installed slave unit 20A. As a result, it becomes easier to secure a detour route.

[0066] <Selection condition F7> Selection condition F7 specifies that the response terminal 20 with the largest field strength value is to be selected. Here, the field strength value indicates the value of the field strength of the radio wave received from the response terminal 20 by the wireless communication unit 62 of the radio wave measurement terminal 60. The processing unit 61 executes a terminal selection process based on selection condition F7 to select the response terminal 20 with the largest field strength value from the remaining response terminals 20.

[0067] Next, the priority order set for each of the multiple selection conditions F (selection conditions F1 to F7) will be described with reference to Fig. 4, Fig. 6, and Fig. 7. Fig. 6 is a diagram showing the priority order (default value) set in advance for each of the multiple selection conditions F (selection conditions F1 to F7). In detail, Fig. 6 shows a priority order table T that specifies the priority order for selection conditions F1 to F7.

[0068] The storage unit 63 of the radio wave measurement terminal 60 stores a priority order set for each of the multiple selection conditions F. In this embodiment, the storage unit 63 of the radio wave measurement terminal 60 stores a priority order table T shown in FIG.

[0069] For example, as shown in Fig. 6, the first priority is set as a default value for selection condition F1. Similarly, the second to seventh priority values ​​are set as default values ​​for selection conditions F2 to F7, respectively.

[0070] If the operator does not instruct to change the priority of the selection condition F, the processing unit 61 first executes a terminal selection process based on the selection condition F1 according to the priority order shown in Fig. 6. As a result, if one communication partner of the newly installed slave unit 20A is not determined, the processing unit 61 executes a terminal selection process based on the selection condition F2 according to the priority order shown in Fig. 6. Thereafter, the processing unit 61 selects the selection condition F according to the priority order shown in Fig. 6 until one communication partner of the newly installed slave unit 20A is determined.

[0071] Fig. 7 is a diagram showing an example of the priority order after being changed based on a priority order change instruction by a worker. In detail, Fig. 7 shows an example of the priority order table T after the priority order has been changed based on a priority order change instruction by a worker.

[0072] For example, as shown in FIG. 7, based on an instruction from an operator to change the priority order, selection conditions F2 to F6 are set to third to seventh priority orders, respectively, and selection condition F7 is set to second priority order.

[0073] When the priority of the selection condition F is changed as shown in Fig. 7, the processing unit 61 first executes a terminal selection process based on the selection condition F1 in accordance with the priority shown in Fig. 7. As a result, when one communication partner of the newly installed slave unit 20A is not determined, the processing unit 61 executes a terminal selection process based on the selection condition F7 in accordance with the priority shown in Fig. 7. Thereafter, the processing unit 61 selects the selection condition F in accordance with the priority shown in Fig. 7 until one communication partner of the newly installed slave unit 20A is determined.

[0074] Next, the selection condition F4 and the selection condition F5 will be further explained with reference to Fig. 4, Fig. 8, and Fig. 9. Fig. 8 is a diagram showing an example of the average field strength X measured by the processing unit 61 of the radio wave measurement terminal 60, and the packet acquisition rate P. Fig. 9 is a diagram showing the maximum fluctuation width D1 of the average field strength measured by the processing unit 61 of the radio wave measurement terminal 60.

[0075] To execute a terminal selection process based on selection conditions F4 and F5, processing unit 61 measures the average field strength X (FIG. 8), the packet acquisition rate P (FIG. 8), and the maximum fluctuation range D1 of the average field strength (FIG. 9).

[0076] In detail, the processing unit 61 requests the remaining response terminals 20 to emit radio waves multiple times in succession by the second and subsequent response request signals. In other words, the processing unit 61 requests the remaining response terminals 20 to transmit response signals multiple times in succession. More specifically, the processing unit 61 causes the remaining response terminals 20 to carry a packet set by the response signal (radio wave). The packet set includes a predetermined number of packets. In this embodiment, the processing unit 61 requests the remaining response terminals 20 to transmit response signals five times in succession.

[0077] The wireless communication unit 62 (wireless communication circuit unit 621) detects, for each packet set, the value of the field intensity of each packet received by the antenna 622. As shown in Fig. 8, the processing unit 61 measures, for each packet set, the average field intensity value X and the packet acquisition rate P.

[0078] More specifically, the processing unit 61 measures the average field strength X for each packet set, based on the value of the field strength of each packet detected by the wireless communication circuit unit 621 .

[0079] The average field strength X indicates the average value of the field strength of each packet that the antenna 622 was able to receive in each response signal (each packet set). Specifically, the average field strength X1 indicates the average value of the field strength of each packet detected when the wireless communication unit 62 receives the first response signal (first packet set). Similarly, the average field strength values ​​X2 to X5 indicate the average values ​​of the field strength of each packet detected when the antenna 622 receives the second to fifth response signals (second to fifth packet sets), respectively.

[0080] The processing unit 61 measures a packet acquisition rate P for each packet set based on the packets received by the wireless communication unit 62. The processing unit 61 uses the packet acquisition rate P when executing a terminal selection process based on the selection condition F5.

[0081] The packet acquisition rate P indicates the number of packets that the wireless communication unit 62 was able to receive from among the multiple packets included in a packet set. Specifically, the packet acquisition rate P1 indicates the number of packets that the wireless communication unit 62 received by the first response signal (first packet set). Similarly, the packet acquisition rates P2 to P5 indicate the numbers of packets that the wireless communication unit 62 received by the second to fifth response signals (second to fifth packet sets), respectively.

[0082] 9, the processing unit 61 further measures a maximum fluctuation width D1 of the average field strength based on the average field strength value X for each measurement. The maximum fluctuation width D1 of the average field strength value indicates the difference between the maximum and minimum values ​​of the average field strength value X. The processing unit 61 obtains the maximum and minimum values ​​from the average field strength value X measured for each packet set, and determines the maximum fluctuation width D1 of the average field strength value. For example, the processing unit 61 may determine the maximum fluctuation width D1 of the average field strength value based on the following formula (1). D1 = |Maximum value {X(1)~X(n)} - Minimum value {X(1)~X(n)} (1)

[0083] In the above formula (1), n ​​is the number of consecutive transmissions of the response signal. For example, if the number of consecutive transmissions of the response signal is 5, the processing unit 61 may obtain the maximum fluctuation width D1 of the average field strength based on the following formula (2). D1=|Maximum value {X1, X2, X3, X4, X5} - Minimum value {X1, X2, X3, X4, X5}...(2)

[0084] The maximum fluctuation range D1 of the average field strength is an example of an index of the stability of the field strength value. More specifically, the smaller the maximum fluctuation range D1 of the average field strength, the more stable the field strength value. The processing unit 61 uses the maximum fluctuation range D1 of the average field strength when executing the terminal selection process based on the selection condition F4. Specifically, the processing unit 61 selects the response terminal 20 with the smallest maximum fluctuation range D1 of the average field strength from among the remaining response terminals 20.

[0085] In addition, in order to perform the terminal selection process based on the selection condition F4 and the selection condition F5, the processing unit 61 may measure the average field strength X, the minimum field strength Xmin, the packet acquisition rate P, and the maximum difference D2 between the average field strength and the minimum field strength.

[0086] Fig. 10 is a diagram showing an example of the average field strength X, the minimum field strength Xmin, and the packet acquisition rate P measured by the processing unit 61 of the radio wave measurement terminal 60. Fig. 11 is a diagram showing the maximum difference D2 between the average field strength and the minimum field strength measured by the processing unit 61 of the radio wave measurement terminal 60.

[0087] The minimum electric field strength value Xmin indicates the minimum value of the electric field strength of each packet in each response signal (each packet set) received by the wireless communication unit 62. The processing unit 61 measures the minimum electric field strength value Xmin for each packet set based on the value of the electric field strength of each packet detected by the wireless communication circuit unit 621.

[0088] Specifically, the minimum field strength value Xmin1 indicates the minimum value of the field strength of each packet detected when the wireless communication unit 62 receives the first response signal (first packet set). Similarly, the minimum field strength values ​​Xmin2 to Xmin5 indicate the minimum values ​​of the field strength of each packet detected when the wireless communication unit 62 receives the second to fifth response signals (second to fifth packet sets), respectively.

[0089] The processing unit 61 further measures a maximum difference D2 between the average field strength value X and the minimum field strength value Xmin for each packet set based on the average field strength value X and the minimum field strength value Xmin. The maximum difference D2 between the average field strength value X and the minimum field strength value Xmin indicates the largest value among the differences between the average field strength value X and the minimum field strength value Xmin for each packet set.

[0090] The processing unit 61 obtains the difference between the average field strength value X and the minimum field strength value Xmin for each packet set, and calculates the maximum difference D2 between the average field strength value and the minimum field strength value. For example, the processing unit 61 may calculate the maximum difference D2 between the average field strength value and the minimum field strength value based on the following formula (3). D2=maximum value{|X(1)-Xmin(1)|~|X(n)-Xmin(n)|}...(3)

[0091] In the above formula (3), n is the number of consecutive transmissions of the response signal. For example, if the number of consecutive transmissions of the response signal is 5, the processing unit 61 may obtain the maximum difference D2 between the average field strength and the minimum field strength based on the following formula (4). D2=maximum value {|X1-Xmin1|, |X2-Xmin2|, |X3-Xmin3|, |X4-Xmin4|, |X5-Xmin5|}...(4)

[0092] The maximum difference D2 between the average field strength value and the minimum field strength value is an example of an index of the stability of the field strength value. More specifically, the smaller the maximum difference D2 between the average field strength value and the minimum field strength value, the more stable the field strength value. The processing unit 61 may use the maximum difference D2 between the average field strength value and the minimum field strength value when executing the terminal selection process based on the selection condition F4. Specifically, the processing unit 61 may select the response terminal 20 with the smallest maximum difference D2 between the average field strength value and the minimum field strength value from among the remaining response terminals 20.

[0093] Next, the selection condition F6 will be further explained with reference to Fig. 4, Fig. 12, and Fig. 13. Fig. 12 is a block diagram showing the configuration of the slave unit 20. Fig. 13 is a diagram showing a communication system 100 (telemetry system 100). In detail, Fig. 13 shows a state in which the slave unit 20f is broadcasting a response request signal (wireless signal).

[0094] First, the configuration of the child device 20 will be described with reference to Fig. 12. As shown in Fig. 12, the child device 20 includes a processing unit 21, a wireless communication unit 22, a connection unit 23, and a storage unit 24. The wireless communication unit 22 includes a wireless communication circuit unit 221 and an antenna 222.

[0095] An electric wire PL, which is connected to the meter 30, is connected to the connection unit 23. Thus, the connection unit 23 is wired to the meter 30 via the electric wire PL. The processing unit 21 acquires a measurement value from the meter 30 via the electric wire PL and the connection unit 23.

[0096] The processing unit 21 controls each element of the child device 20. For example, the processing unit 21 controls the wireless communication unit 22 and the storage unit 24. The processing unit 21 includes a processor such as a CPU or an MPU. The processor controls each element of the child device 20 by executing a computer program stored in the storage unit 24. The processing unit 21 and the storage unit 24 may form a microcomputer.

[0097] The wireless communication unit 22 performs wireless communication. Specifically, the wireless communication unit 22 transmits and receives radio waves (wireless signals). The configuration of the wireless communication unit 22 is substantially the same as that of the wireless communication unit 62 of the radio wave measurement terminal 60, and therefore a detailed description thereof will be omitted.

[0098] The storage unit 24 stores identification information for identifying the device itself and identification information for identifying a communication partner of the device. The storage unit 24 also stores various computer programs executed by the processing unit 21 (processor). The storage unit 24 includes, for example, a semiconductor memory such as a ROM, a RAM, and a flash memory.

[0099] Next, the process executed by the processing unit 21 of the response terminal 20 will be described using the slave 20f (FIG. 13) as an example. In order to execute the terminal selection process based on the selection condition F6, the processing unit 61 (FIG. 4) of the radio wave measurement terminal 60 requests the processing unit 21 of the slave 20f (remaining response terminal 20) to respond with the number of slaves 20 that can communicate with the processing unit 21 (slave 20f) by the second or subsequent response request signal.

[0100] The processing unit 21 of the slave device 20f broadcasts a response request signal in response to a request from the radio wave measurement terminal 60. The response request signal transmitted from the slave device 20f includes identification information for identifying the slave device itself (slave device 20f). The response request signal transmitted from the slave device 20f is received by other slave devices 20 installed within the communication distance range of the slave device 20f.

[0101] For example, as shown in Fig. 13, slave units 20a to 20e and 20g to 20k are installed within the communication distance range of slave unit 20f. Therefore, the response request signal transmitted from slave unit 20f is received by slave units 20a to 20e and 20g to 20k.

[0102] Each of the slave units 20a to 20e and 20g to 20k that have received the response request signal transmits a response signal to the slave unit 20f. The wireless communication unit 22 (wireless communication circuit unit 221) of the slave unit 20f detects the value of the field intensity of the radio waves received from the slave units 20a to 20e and 20g to 20k, and outputs the value to the processing unit 21.

[0103] The processing unit 21 of the slave unit 20f acquires the number of peripheral terminals based on the value of the electric field strength detected by the wireless communication unit 22. Specifically, the processing unit 21 of the slave unit 20f acquires the number of slave units 20 whose electric field strength values ​​detected by the wireless communication unit 22 are equal to or greater than the first reference value Q1. The processing unit 21 of the slave unit 20f transmits a response signal indicating the acquired number of peripheral terminals to the radio wave measurement terminal 60.

[0104] Although the radio wave measurement terminal 60 is also present within the communication distance of the response terminal 20, the computer program stored in the storage unit 63 of the radio wave measurement terminal 60 is designed so that the processing unit 61 does not respond to a response request signal transmitted from the response terminal 20. Alternatively, the processing unit 21 of the response terminal 20 may add "-1" to the acquired number of surrounding terminals.

[0105] Next, the processing executed by the processing unit 61 of the radio wave measurement terminal 60 will be described with reference to Fig. 1 to Fig. 18. Fig. 14 to Fig. 18 are flowcharts showing the processing executed by the processing unit 61 of the radio wave measurement terminal 60. The processing shown in Fig. 14 to Fig. 18 is started when an operator operates the operation unit 64 of the radio wave measurement terminal 60.

[0106] When an operator operates the operation unit 64 of the radio wave measurement terminal 60, the processing unit 61 of the radio wave measurement terminal 60 decides whether or not to change the priority of the selection condition F depending on whether or not the operation unit 64 has accepted an instruction from the operator to change the priority (step S1).

[0107] When the operation unit 64 receives an instruction to change the priority order from the operator, the processing unit 61 of the radio wave measurement terminal 60 decides to change the priority order of the selection condition F (Yes in step S1). Then, based on the instruction to change the priority order, the processing unit 61 changes the priority order of the selection condition F (step S2).

[0108] When the processing unit 61 of the radio wave measurement terminal 60 changes the priority of the selection condition F, it causes the wireless communication unit 62 to broadcast a first response request signal (step S3). Alternatively, if the operation unit 64 does not accept an instruction from the operator to change the priority, the processing unit 61 of the radio wave measurement terminal 60 decides not to change the priority of the selection condition F (No in step S1) and causes the wireless communication unit 62 to broadcast a first response request signal (step S3).

[0109] After the first response request signal is broadcast, processing unit 61 of radio wave measurement terminal 60 receives the response signal via wireless communication unit 62 (step S4). More specifically, the first response request signal requests information on the number of relay steps from child device 20. Memory unit 24 (FIG. 12) of child device 20 stores information on the number of relay steps, and response terminal 20 transmits a response signal indicating the number of relay steps to radio wave measurement terminal 60 in response to the first response request signal.

[0110] When the processing unit 61 of the radio wave measurement terminal 60 receives the response signal via the wireless communication unit 62, it selects one of the multiple selection conditions F (selection conditions F1 to F7) in accordance with the priority set for each of the multiple selection conditions F. Specifically, the processing unit 61 of the radio wave measurement terminal 60 assigns "1" to the value of the variable N and selects the selection condition F with the Nth priority (step S5). In other words, the processing unit 61 of the radio wave measurement terminal 60 selects the selection condition F with the first priority. In this embodiment, the processing unit 61 selects selection condition F1.

[0111] When the processing unit 61 of the radio wave measurement terminal 60 selects the selection condition F1, it executes a terminal selection process based on the selection condition F1 (step S6). Specifically, the processing unit 61 of the radio wave measurement terminal 60 selects, from among the response terminals 20, a response terminal 20 whose field strength value is equal to or greater than a first reference value Q1, based on the field strength value of the first response signal (radio wave) detected by the wireless communication unit 62.

[0112] The processing unit 61 of the radio wave measurement terminal 60 executes a terminal selection process based on the selection condition F1 to determine whether or not there is a response terminal 20 that matches the selection condition F1 (step S7). Specifically, the processing unit 61 of the radio wave measurement terminal 60 determines whether or not there is a response terminal 20 whose field strength value is equal to or greater than the first reference value Q1.

[0113] If there is no response terminal 20 that matches the selection condition F1 (No in step S7), the processing unit 61 of the radio wave measurement terminal 60 executes a display process (step S9) and ends the processes shown in Fig. 14 to Fig. 18. In detail, in the display process, the processing unit 61 of the radio wave measurement terminal 60 causes the display unit 65 to display information indicating that there is no slave unit 20 with which the newly installed slave unit 20A can communicate. For example, the display unit 65 displays a message indicating that there is no slave unit 20 with which the newly installed slave unit 20A can communicate.

[0114] If there is a response terminal 20 that meets the selection condition F1 (Yes in step S7), the processing unit 61 of the radio wave measurement terminal 60 determines whether the number of response terminals 20 selected based on the selection condition F1 is one or not (step S8).

[0115] If the number of remaining response terminals 20 is one (Yes in step S8), the processing unit 61 of the radio wave measurement terminal 60 executes a display process (step S9) and ends the processes shown in Fig. 14 to Fig. 18. In detail, in the display process, the processing unit 61 of the radio wave measurement terminal 60 causes the display unit 65 to display information that identifies the slave unit 20 that will be a communication partner of the newly installed slave unit 20A. For example, the display unit 65 displays identification information of the slave unit 20 that will be a communication partner of the newly installed slave unit 20A.

[0116] When the number of remaining response terminals 20 is not one but multiple (No in step S8), the processing unit 61 of the radio wave measurement terminal 60 selects one of the multiple selection conditions F (selection conditions F1 to F7) according to the priority set for each of the multiple selection conditions F, as shown in Fig. 15. Specifically, the processing unit 61 of the radio wave measurement terminal 60 assigns "N+1" to the variable N and selects the selection condition F with the N+1th priority (step S10). For example, when the current value of the variable N is "1", the processing unit 61 of the radio wave measurement terminal 60 selects the selection condition F with the second highest priority.

[0117] When the processing unit 61 of the radio wave measurement terminal 60 selects the selection condition F with the N+1th priority, it determines whether the selection condition F with the N+1th priority is one of the selection condition F2 and the selection condition F7 (step S11).

[0118] If the selection condition F with the N+1th priority is one of the selection condition F2 and the selection condition F7 (Yes in step S11), the processing unit 61 of the radio wave measurement terminal 60 executes a terminal selection process based on the selection condition F2 or the selection condition F7 (step S12).

[0119] Specifically, when executing a terminal selection process based on selection condition F2, the processing unit 61 of the radio wave measurement terminal 60 selects, from the remaining response terminals 20, the response terminal 20 with the fewest number of relay steps, based on information on the number of relay steps included in the first response signal received from the response terminal 20. When executing a terminal selection process based on selection condition F7, the processing unit 61 of the radio wave measurement terminal 60 selects, from the remaining response terminals 20, the response terminal 20 with the largest field strength value, based on the field strength value of the first response signal (radio wave) detected by the wireless communication unit 62.

[0120] After selecting a response terminal 20 based on the selection condition F2 or F7, the processing unit 61 of the radio wave measurement terminal 60 determines whether the number of remaining response terminals 20 is one or not (step S13).

[0121] If the number of remaining response terminals 20 is one (Yes in step S13), the processing unit 61 of the radio wave measurement terminal 60 executes a display process (step S9) and ends the processes shown in Figures 14 to 18. If the number of remaining response terminals 20 is not one but multiple (No in step S13), the process returns to step S10.

[0122] If the selection condition F with the N+1th priority is not one of selection condition F2 and selection condition F7 (No in step S11), that is, if the selection condition F with the N+1th priority is neither selection condition F2 nor selection condition F7, as shown in FIG. 16, the processing unit 61 of the radio wave measurement terminal 60 determines whether the selection condition F with the N+1th priority is selection condition F3 (step S14).

[0123] If the selection condition F with the N+1th priority is selection condition F3 (Yes in step S14), the processing unit 61 of the radio wave measurement terminal 60 causes the wireless communication unit 62 to transmit a response request signal to the remaining response terminals 20, requesting information on the number of subordinate sub-units (step S15).

[0124] The response terminal 20 that has received the response request signal requesting information on the number of subordinate slave units transmits a response signal indicating the number of subordinate slave units to the radio wave measurement terminal 60. Specifically, the processing unit 21 of the response terminal 20 obtains, from the storage unit 24, identification information for identifying the communication partner of the response terminal 20, and obtains the number of subordinate slave units.

[0125] When the processing unit 61 of the radio wave measurement terminal 60 receives the response signal via the wireless communication unit 62 (step S16), it acquires the subordinate slave number information from the response signal. Then, the processing unit 61 of the radio wave measurement terminal 60 executes a terminal selection process based on the selection condition F3 (step S17). Specifically, the processing unit 61 of the radio wave measurement terminal 60 selects the response terminal 20 with the least number of subordinate slaves from among the remaining response terminals 20 based on the subordinate slave number information.

[0126] After executing the terminal selection process based on the selection condition F3, the processing unit 61 of the radio wave measurement terminal 60 determines whether the number of remaining response terminals 20 is one or not (step S13).

[0127] If the number of remaining response terminals 20 is one (Yes in step S13), the processing unit 61 of the radio wave measurement terminal 60 executes a display process (step S9) and ends the processes shown in Figures 14 to 18. If the number of remaining response terminals 20 is not one but multiple (No in step S13), the process returns to step S10 shown in Figure 15.

[0128] If the selection condition F with the N+1th priority is not selection condition F3 (No in step S14), as shown in FIG. 17, the processing unit 61 of the radio wave measurement terminal 60 determines whether the selection condition F with the N+1th priority is one of selection condition F4 and selection condition F5 (step S18).

[0129] When the selection condition F with the N+1th priority is one of the selection conditions F4 and F5 (Yes in step S18), the processing unit 61 of the radio wave measurement terminal 60 causes the wireless communication unit 62 to transmit a response request signal requesting that the packet set be carried multiple times in succession to the remaining response terminals 20 (step S19), as described with reference to Fig. 8. As a result, the remaining response terminals 20 transmit the response signal multiple times in succession to the radio wave measurement terminal 60. In this embodiment, the remaining response terminals 20 transmit the response signal five times in succession.

[0130] When the processing unit 61 of the radio wave measurement terminal 60 receives the response signal via the wireless communication unit 62 (step S20), it measures the packet acquisition rate P and the maximum fluctuation width D1 of the average field strength, as described with reference to Figures 8 and 9. Alternatively, the processing unit 61 of the radio wave measurement terminal 60 may measure the packet acquisition rate P and the maximum difference D2 between the average field strength and the minimum field strength, as described with reference to Figures 10 and 11. After receiving the response signal via the wireless communication unit 62, the processing unit 61 of the radio wave measurement terminal 60 executes a terminal selection process based on the selection condition F4 or the selection condition F5 (step S21).

[0131] Specifically, when executing a terminal selection process based on selection condition F4, the processing unit 61 of the radio wave measurement terminal 60 selects, from the remaining response terminals 20, the response terminal 20 having the smallest maximum fluctuation width D1 of the average field strength. Alternatively, the processing unit 61 of the radio wave measurement terminal 60 selects, from the remaining response terminals 20, the response terminal 20 having the smallest maximum difference D2 between the average field strength and the minimum field strength. When executing a terminal selection process based on selection condition F5, the processing unit 61 of the radio wave measurement terminal 60 selects, from the remaining response terminals 20, the response terminal 20 having the largest packet acquisition rate P.

[0132] After selecting a response terminal 20 based on the selection condition F4 or F5, the processing unit 61 of the radio wave measurement terminal 60 determines whether the number of remaining response terminals 20 is one or not (step S13).

[0133] If the number of remaining response terminals 20 is one (Yes in step S13), the processing unit 61 of the radio wave measurement terminal 60 executes a display process (step S9) and ends the processes shown in Figures 14 to 18. If the number of remaining response terminals 20 is not one but multiple (No in step S13), the process returns to step S10 shown in Figure 15.

[0134] If the selection condition F with the N+1th priority is not one of selection condition F4 and selection condition F5 (No in step S18), that is, if the selection condition F with the N+1th priority is neither selection condition F4 nor selection condition F5, as shown in FIG. 18, the processing unit 61 of the radio wave measurement terminal 60 causes the wireless communication unit 62 to transmit a response request signal requesting information on the number of surrounding terminals to the remaining response terminals 20 (step S22).

[0135] The processing unit 21 of the responding terminal 20 that receives the response request signal requesting information on the number of surrounding terminals acquires the number of surrounding terminals as described with reference to Figures 12 and 13, and transmits a response signal indicating the number of surrounding terminals to the radio wave measurement terminal 60.

[0136] When the processing unit 61 of the radio wave measurement terminal 60 receives the response signal via the wireless communication unit 62 (step S23), it acquires peripheral terminal number information from the response signal. Then, the processing unit 61 of the radio wave measurement terminal 60 executes a terminal selection process based on the selection condition F6 (step S24). Specifically, the processing unit 61 of the radio wave measurement terminal 60 selects a response terminal 20 whose peripheral terminal number is equal to or greater than the second reference value Q2 from among the remaining response terminals 20 based on the peripheral terminal number information.

[0137] After selecting a response terminal 20 based on the selection condition F6, the processing unit 61 of the radio wave measurement terminal 60 determines whether or not the number of remaining response terminals 20 is one (step S13).

[0138] If the number of remaining response terminals 20 is one (Yes in step S13), the processing unit 61 of the radio wave measurement terminal 60 executes a display process (step S9) and ends the processes shown in Figures 14 to 18. If the number of remaining response terminals 20 is not one but multiple (No in step S13), the process returns to step S10 shown in Figure 15.

[0139] In the processing described with reference to Figures 14 to 18, the processing unit 61 of the radio wave measurement terminal 60 executes a terminal selection process based on selection condition F1 and a terminal selection process based on selection condition F7 based on the field strength value acquired by the first response request signal, but when executing the terminal selection process based on selection condition F7, the processing unit 61 of the radio wave measurement terminal 60 may transmit a response request signal to the remaining response terminals 20 to acquire the field strength values.

[0140] Similarly, in the processing described with reference to Figures 14 to 18, the processing unit 61 of the radio wave measurement terminal 60 obtained the relay number information by the first response request signal, but when executing the terminal selection processing based on selection condition F2, the processing unit 61 of the radio wave measurement terminal 60 may transmit a response request signal to the remaining response terminals 20 to obtain the relay number information.

[0141] Furthermore, in the processing described with reference to Figures 14 to 18, the processing unit 61 of the radio wave measurement terminal 60 measured the maximum fluctuation range D1 of the average field strength or the maximum difference D2 between the average field strength and the minimum field strength, and the packet acquisition rate P by transmitting a single response request signal, but the processing unit 61 of the radio wave measurement terminal 60 may transmit a response request signal when executing a terminal selection process based on selection condition F4 and when executing a terminal selection process based on selection condition F5, and measure the maximum fluctuation range D1 of the average field strength or the maximum difference D2 between the average field strength and the minimum field strength when executing the terminal selection process based on selection condition F4, and measure the packet acquisition rate P when executing the terminal selection process based on selection condition F5.

[0142] Next, an example of the process executed by the radio wave measurement terminal 60 will be described with reference to Fig. 3, Fig. 7, and Fig. 19. Fig. 19 is a sequence diagram showing an example of the process executed by the radio wave measurement terminal 60. More specifically, Fig. 19 shows an example of the process executed after the priority of the selection condition F is changed by the worker to the priority shown in Fig. 7.

[0143] In the following description, the handset 20h may be referred to as the "first handset 20h." Similarly, the handset 20i, 20f, 20j, and 20k may be referred to as the "second handset 20i," the "third handset 20f," the "fourth handset 20j," and the "fifth handset 20k," respectively.

[0144] 19, the radio wave measurement terminal 60 broadcasts a first response request signal. In this embodiment, the first handset 20h to the fifth handset 20k receive the first response request signal and transmit response signals to the radio wave measurement terminal 60.

[0145] When the radio wave measurement terminal 60 receives the response signal, it executes a terminal selection process based on the selection condition F1. In the example shown in Fig. 19, since the values ​​of the electric field strength of the radio waves received from the first handset 20h and the third handset 20f are less than the first reference value Q1, the second handset 20i, the fourth handset 20j, and the fifth handset 20k are selected by the terminal selection process based on the selection condition F1. Therefore, the number of remaining response terminals 20 is more than one.

[0146] As shown in Fig. 7, the selection condition F with the second highest priority is selection condition F7. In the example shown in Fig. 19, the radio wave measurement terminal 60 transmits a second response request signal to the remaining response terminals 20, that is, the second handset 20i, the fourth handset 20j, and the fifth handset 20k, and receives response signals from the second handset 20i, the fourth handset 20j, and the fifth handset 20k.

[0147] When the radio wave measurement terminal 60 receives the response signal, it executes a terminal selection process based on the selection condition F7. In the example shown in Fig. 19, the field strength value Z1 of the radio waves received from the second handset 20i and the fifth handset 20k is greater than the field strength value Z2 of the radio waves received from the fourth handset 20j, and the field strength values ​​Z1 of the radio waves received from the second handset 20i and the fifth handset 20k are the same value. Therefore, the second handset 20i and the fifth handset 20k are selected by the terminal selection process based on the selection condition F7, and the number of remaining response terminals 20 becomes more than one.

[0148] As shown in Fig. 7, the selection condition F with the third priority is selection condition F2. In the example shown in Fig. 19, the radio wave measurement terminal 60 transmits a third response request signal to the remaining response terminals 20, that is, the second handset 20i and the fifth handset 20k, and receives response signals from the second handset 20i and the fifth handset 20k.

[0149] When the radio wave measurement terminal 60 receives the response signal, it executes a terminal selection process based on the selection condition F2. As shown in Fig. 3, the number of relay stages of the second handset 20i is three, and the number of relay stages of the fifth handset 20k is four. Therefore, the second handset 20i is selected by the terminal selection process based on the selection condition F2, and the number of remaining response terminals 20 becomes one.

[0150] When the number of remaining response terminals 20 becomes one, the radio wave measurement terminal 60 executes a display process. In detail, the radio wave measurement terminal 60 displays, on the display unit 65, information for identifying the slave terminal 20 (the second slave terminal 20i) that will be the communication partner of the newly-installed slave terminal 20A.

[0151] Next, the radio wave measurement terminal 60 will be further described with reference to Fig. 4 and Fig. 20 to Fig. 22. Fig. 20 is a diagram showing the configuration of an operation unit 64 of the radio wave measurement terminal 60. As shown in Fig. 20, the operation unit 64 of the radio wave measurement terminal 60 has a plurality of hard keys 640. The plurality of hard keys 640 includes a numeric keypad 641, a direction key 642, and an enter key 643.

[0152] Fig. 21 is a diagram showing a first input screen G1 displayed on the display unit 65 of the radio wave measurement terminal 60. The first input screen G1 is a screen for inquiring of the operator as to whether or not to change the priority order set for each of a plurality of selection conditions F. As shown in Fig. 21, the first input screen G1 displays a message M, a first button M1, and a second button M2.

[0153] The message M is an image showing a message inquiring to the worker whether or not to change the priority order set for each of the multiple selection conditions F. The first button M1 and the second button M2 are button images. The worker can operate the directional key 642 to select one of the first button M1 and the second button M2.

[0154] When the worker presses the decision key 643 after selecting the first button M1, the display unit 65 displays the second input screen G2 shown in Fig. 22. On the other hand, when the worker presses the decision key 643 after selecting the second button M2, the processing unit 61 of the radio wave measurement terminal 60 decides not to change the priority of the selection condition F.

[0155] 22 is a diagram showing a second input screen G2 displayed on the display unit 65 of the radio wave measurement terminal 60. The second input screen G2 displays a first input field B1 to a sixth input field B6, and a third button M3.

[0156] The first to sixth input fields B1 to B6 are fields for inputting the priorities of the selection conditions F2 to F7, respectively. The third button M3 is a button image.

[0157] The worker operates the direction key 642 to select one of the first input field B1 to the sixth input field B6, and then operates the numeric keypad 641 to input a numerical value into the selected input field.

[0158] After entering numerical values ​​in all of the first input field B1 to the sixth input field B6, the worker operates the directional key 642 to select the third button M3 and presses the decision key 643 to set the priority order of selection conditions F2 to F7.

[0159] In the second input screen G2 described with reference to FIG. 22, the worker operates the numeric keypad 641 to input the priority order of selection conditions F2 to F7, but the second input screen G2 may be an input screen for inputting the priority order of selection conditions F2 to F7 in the form of a pull-down menu.

[0160] Furthermore, in the second input screen G2 described with reference to FIG. 22, the worker operates the numeric keypad 641 to input the priorities of all of the selection conditions F2 to F7, but as shown in FIG. 23, the second input screen G2 may be an input screen that allows the worker to select the priority of one of the selection conditions F from among the selection conditions F2 to F7.

[0161] Fig. 23 is a diagram showing a modified example of the second input screen G2. The second input screen G2 shown in Fig. 23 displays a first radio button R1 to a sixth radio button R6 and a third button M3.

[0162] By selecting one of the first radio button R1 to the sixth radio button R6, the operator can set the priority of one of the selection conditions F2 to F7 to second place. For example, by selecting the first radio button R1, the priority of the selection condition F2 is set to second place.

[0163] Specifically, the worker operates the directional key 642 to select one of the first radio button R1 to the sixth radio button R6, and then operates the directional key 642 to select the third button M3 and presses the enter key 643. As a result, the processing unit 61 sets the priority of the selection condition F corresponding to the selected radio button to second. Also, the processing unit 61 lowers the priority of the remaining selection condition F among selection conditions F2 to F7 by one. For example, when the priority of selection condition F7 is set to second, the processing unit 61 changes the priority of selection conditions F2 to F6 to third to seventh, respectively.

[0164] The first embodiment of the present invention has been described above with reference to Fig. 1 to Fig. 23. According to this embodiment, the operator can change the priority order of the selection conditions F.

[0165] For example, the worker can change the priority of the selection condition F depending on the environment of the site. As a result, compared to a case where the priority of the selection condition F is fixed, a communication partner suitable for the environment of the site can be selected as the communication partner of the newly installed slave unit 20A.

[0166] Specifically, by setting the priority of the selection condition F7 to the second place, the worker can select the slave device 20 having the highest field strength value as the communication partner of the newly installed slave device 20A. Also, by setting the priority of the selection condition F5 to the second place, the worker can select the slave device 20 having the least packet loss as the communication partner of the newly installed slave device 20A.

[0167] In addition, according to this embodiment, the worker can change the priority of selection condition F, thereby reducing the risk of the task of selecting a communication partner for the newly installed handset 20A taking a long time compared to when the priority of selection condition F is fixed.

[0168] For example, if the priority order of the selection conditions F1 to F7 is fixed as shown in Fig. 6, it may not be possible to determine a communication partner for the newly installed slave device 20A until a terminal selection process based on the selection condition F7 is executed. In contrast, according to this embodiment, the worker can set the priority order of the selection condition F7 to second, thereby preventing the work of selecting a communication partner for the newly installed slave device 20A from being prolonged.

[0169] The display unit 65 may display the field strength value detected by the first response request signal. By displaying the field strength value detected by the first response request signal, the worker can determine the communication environment at the site and change the priority order of the selection condition F.

[0170] [Embodiment 2] Next, a second embodiment of the present invention will be described with reference to Fig. 4 and Fig. 24 to Fig. 26. However, only differences from the first embodiment will be described, and explanations of the same matters as in the first embodiment will be omitted. The second embodiment differs from the first embodiment in that the processing unit 61 of the radio wave measurement terminal 60 changes the priority order of the selection condition F based on a response signal.

[0171] Fig. 24 is a flowchart showing the processing executed by the processing unit 61 of the radio wave measurement terminal 60. The processing shown in Fig. 24 is started when the operator operates the operation unit 64 of the radio wave measurement terminal 60.

[0172] When an operator operates the operation unit 64 of the radio wave measurement terminal 60, the processing unit 61 causes the wireless communication unit 62 to broadcast a first response request signal (step S31).

[0173] After broadcasting the first response request signal, the processing unit 61 receives a response signal via the wireless communication unit 62 (step S32). Based on the response signal, the processing unit 61 obtains the number of slave units 20 installed within the communication distance range of the radio wave measurement terminal 60. In other words, the processing unit 61 obtains the number of response terminals 20. Hereinafter, the number of response terminals 20 may be referred to as the "number of surrounding terminals."

[0174] When the processing unit 61 receives the response signal via the wireless communication unit 62, the processing unit 61 executes a decision process to decide whether or not to change the priority order of the selection condition F (step S33). Specifically, the processing unit 61 decides whether or not to change the priority order of the selection condition F based on the number of surrounding terminals.

[0175] When the processing unit 61 determines to change the priority of the selection condition F (Yes in step S33), it changes the priority of the selection condition F based on the response signal (step S34).

[0176] When the processing unit 61 changes the priority of the selection condition F, it selects one of the multiple selection conditions F (selection conditions F1 to F7) according to the priority set for each of the multiple selection conditions F. Specifically, the processing unit 61 assigns "1" to the value of the variable N and selects the selection condition F with the Nth priority (step S35). Alternatively, when the processing unit 61 decides not to change the priority of the selection condition F (No in step S33), it assigns "1" to the value of the variable N and selects the selection condition F with the Nth priority (step S35).

[0177] The process after selecting the selection condition F with the Nth priority is the same as the process shown in FIGS. 14 to 18, and therefore the description thereof will be omitted.

[0178] Next, the determination process (step S33) will be described with reference to Fig. 25. Fig. 25 is a flowchart showing the determination process (step S33) executed by the processing unit 61 of the radio wave measurement terminal 60.

[0179] As shown in FIG. 25, when starting the determination process, the processing unit 61 determines whether or not the number of surrounding terminals is equal to or greater than a first specified value (step S41).

[0180] If the number of surrounding terminals is equal to or greater than the first specified value (Yes in step S41), the processing unit 61 decides to change the priority of selection condition F (step S44) and ends the processing shown in Fig. 25. When the processing unit 61 decides to change the priority of selection condition F, it changes the priority of selection condition F based on the number of surrounding terminals (step S34 in Fig. 24).

[0181] If the number of surrounding terminals is not equal to or greater than the first specified value (No in step S41), the processing unit 61 determines whether the number of surrounding terminals is equal to or less than a second specified value (step S42). The second specified value indicates a value lower than the first specified value.

[0182] If the number of surrounding terminals is equal to or less than the second specified value (Yes in step S42), the processing unit 61 decides to change the priority of selection condition F (step S44) and ends the processing shown in Fig. 25. When the processing unit 61 decides to change the priority of selection condition F, it changes the priority of selection condition F based on the number of surrounding terminals (step S34 in Fig. 24).

[0183] If the number of surrounding terminals is not equal to or less than the second specified value (No in step S42), the processing unit 61 determines not to change the priority order of the selection condition F (step S43), and ends the processing shown in FIG.

[0184] According to this embodiment, when the number of surrounding terminals is equal to or greater than a first specified value, the priority of the selection condition F is changed. For example, when the number of surrounding terminals is equal to or greater than a first specified value, the processing unit 61 changes the priority of the selection condition F3 to second.

[0185] Specifically, when there are many surrounding terminals, there is a possibility that each responding terminal 20 has a large number of subordinate slave units. If a slave unit 20 with a large number of subordinate slave units is selected as the communication partner of the newly installed slave unit 20A, there is a possibility that the load will be concentrated on the slave unit 20 that has become the communication partner of the newly installed slave unit 20A. In response to this, by giving the second priority to the selection condition F3, it is possible to select a slave unit 20 with a small number of subordinate slave units as the communication partner of the newly installed slave unit 20A. As a result, it is possible to distribute the load.

[0186] Furthermore, according to this embodiment, when the number of surrounding terminals is equal to or less than a second specified value, the priority of selection condition F is changed. For example, when the number of surrounding terminals is equal to or less than a second specified value, the processing unit 61 changes the priority of selection condition F4 and selection condition F5 to second and third, respectively. Alternatively, the processing unit 61 changes the priority of selection condition F4 and selection condition F5 to third and second, respectively.

[0187] In detail, when the number of terminals around the newly installed handset 20A is small, when the newly installed handset 20A is unable to communicate with the handset 20 selected as the communication partner of the newly installed handset 20A, there is a possibility that communication via a detour route is also impossible. In response to this, by increasing the priority order of the selection condition F4 and the selection condition F5, the handset 20 with the most stable field strength value or the handset 20 with the least packet loss can be selected as the communication partner of the newly installed handset 20A. As a result, the stability of communication between the newly installed handset 20A and the handset 20 selected as the communication partner of the newly installed handset 20A can be improved. In other words, when there is a high possibility that communication via a detour route is impossible, a handset 20 with a lower possibility of being unable to communicate with the newly installed handset 20A can be selected as the communication partner of the newly installed handset 20A.

[0188] Next, a modified example of the determination process (step S33) will be described with reference to Fig. 26. Fig. 26 is a flowchart showing a modified example of the determination process (step S33) executed by the processing unit 61 of the radio wave measurement terminal 60.

[0189] In the process shown in FIG. 26, the processing unit 61 of the radio wave measurement terminal 60 determines whether or not to change the priority order of the selection condition F based on the field intensity value of the response signal (radio wave) to the first response request signal.

[0190] As shown in FIG. 26, when the processing unit 61 starts the decision process, it determines whether all of the field strength values ​​of the response signals (radio waves) received by the wireless communication unit 62 are greater than or equal to the first reference value Q1 and less than or equal to the third specified value (step S51).

[0191] If all of the field strength values ​​of the response signals received by the wireless communication unit 62 are equal to or greater than the first reference value Q1 and equal to or less than the third specified value (Yes in step S51), the processing unit 61 decides to change the priority of selection condition F (step S52) and ends the process shown in Fig. 26. When the processing unit 61 decides to change the priority of selection condition F, it changes the priority of selection condition F based on the field strength values ​​(step S34 in Fig. 24).

[0192] If at least a portion of the electric field strength values ​​of the response signal received by the wireless communication unit 62 is not greater than the first reference value Q1 and not greater than the third specified value (No in step S51), the processing unit 61 decides not to change the priority of the selection condition F (step S53) and terminates the processing shown in FIG. 26.

[0193] 26, when all of the field strength values ​​of the response signals received by the wireless communication unit 62 are equal to or greater than the first reference value Q1 and equal to or less than the third specified value, the priority of the selection condition F is changed. For example, when all of the field strength values ​​of the response signals received by the wireless communication unit 62 are equal to or greater than the first reference value Q1 and equal to or less than the third specified value, the processing unit 61 changes the priority of the selection condition F4 to second.

[0194] In detail, when all of the field strength values ​​of the response signals received by the wireless communication unit 62 are close to the first reference value Q1, the communication between the newly installed handset 20A and the handset 20 selected as the communication partner of the newly installed handset 20A is likely to become unstable. In response to this, by increasing the priority of the selection condition F4, the handset 20 with the most stable field strength value can be selected as the communication partner of the newly installed handset 20A. As a result, the stability of the communication between the newly installed handset 20A and the handset 20 selected as the communication partner of the newly installed handset 20A can be improved.

[0195] The second embodiment of the present invention has been described above with reference to Fig. 4 and Fig. 24 to Fig. 26. According to this embodiment, the processing unit 61 of the radio wave measurement terminal 60 can change the priority order of the selection condition F based on the response signal.

[0196] 26, the processing unit 61 determines whether or not all of the field strength values ​​of the response signals (radio waves) received by the wireless communication unit 62 are equal to or greater than the first reference value Q1 and equal to or less than the third specified value, but the processing unit 61 may determine whether or not the sum of the field strength values ​​of the response signals is equal to or greater than the first reference value Q1 and equal to or less than the third specified value. Alternatively, the processing unit 61 may determine whether or not the average of the field strength values ​​of the response signals is equal to or greater than the first reference value Q1 and equal to or less than the third specified value.

[0197] The embodiments of the present invention have been described above with reference to the drawings (FIGS. 1 to 26). However, the present invention is not limited to the above embodiments, and can be implemented in various aspects without departing from the gist of the present invention. In addition, the components disclosed in the above embodiments can be modified as appropriate. For example, a certain component among all the components shown in one embodiment may be added to a component of another embodiment, or some components among all the components shown in one embodiment may be deleted from the embodiment.

[0198] The drawings are mainly schematic illustrations of each component to facilitate understanding of the invention, and the thickness, length, number, spacing, etc. of each component shown in the drawings may differ from the actual ones due to the convenience of creating the drawings. Furthermore, the configurations of each component shown in the above embodiment are merely examples and are not particularly limited, and it goes without saying that various modifications are possible within a range that does not substantially deviate from the effects of the present invention.

[0199] For example, in the embodiment described with reference to Figures 1 to 26, the slave unit 20 and the meter 30 are wired and connected by an electric wire PL, but the slave unit 20 and the meter 30 may be wirelessly connected. Similarly, in the embodiment described with reference to Figures 1 to 26, the master unit 10 and the meter 30 are wired and connected by an electric wire PL, but the master unit 10 and the meter 30 may be wirelessly connected.

[0200] In the embodiment described with reference to FIGS. 1 to 26, the meter 30 is connected to the master unit 10, but the meter 30 does not have to be connected to the master unit 10. In the embodiment described with reference to FIGS.

[0201] 1 to 26, only child devices 20 (child devices 20h, 20i, 20f, 20j, 20k) are installed within the communication distance of radio wave measurement terminal 60, but parent device 10 may be installed within the communication distance of radio wave measurement terminal 60. In this case, parent device 10 responds to a response request signal from radio wave measurement terminal 60, just like child devices 20.

[0202] In the embodiment described with reference to FIGS. 1 to 26, only the first response request signal is broadcast, but second and subsequent response request signals may also be broadcast.

[0203] In the embodiment described with reference to Figs. 1 to 26, the radio wave measuring terminal 60 acquires the relay number information, the subordinate child device number information, and the peripheral terminal number information by transmitting a response request signal three times. Specifically, the radio wave measuring terminal 60 transmits a response request signal requesting the relay number information, a response request signal requesting the subordinate child device number information, and a response request signal requesting the peripheral terminal number. However, the embodiment according to the present invention is not limited to a configuration in which the relay number information, the subordinate child device number information, and the peripheral terminal number information are acquired by transmitting a response request signal three times. The radio wave measuring terminal 60 may acquire the relay number information, the subordinate child device number information, and the peripheral terminal number information by transmitting a response request signal once or twice. For example, the radio wave measuring terminal 60 may transmit a response request signal requesting all of the relay number information, the subordinate child device number information, and the peripheral terminal number information.

[0204] Furthermore, in the embodiment described with reference to Figures 1 to 26, the radio wave measurement terminal 60 transmitted a response request signal multiple times to acquire information for executing the terminal selection process based on selection condition F1 to the terminal selection process based on selection condition F7, but the radio wave measurement terminal 60 may acquire information for executing the terminal selection process based on selection condition F1 to the terminal selection process based on selection condition F7 by a single response request signal.

[0205] Furthermore, in the embodiment described with reference to FIGS. 1 to 26, the priority order of the selection condition F1 is fixed, but the priority order of the selection condition F1 may be changeable.

[0206] In addition, in the embodiment described with reference to FIGS. 1 to 26, the multiple selection conditions F include selection conditions F1 to F7, but the multiple selection conditions F may include some of selection conditions F1 to F7.

[0207] Furthermore, in the embodiment described with reference to Figures 1 to 26, the radio wave measurement terminal 60 requested the remaining response terminals 20 to transmit multiple packet sets in order to execute the terminal selection process based on selection conditions F4 and F5, but the radio wave measurement terminal 60 may also request the remaining response terminals 20 to receive multiple packet sets (first radio waves).

[0208] In detail, the radio wave measurement terminal 60 may request the remaining response terminals 20 to receive a plurality of packet sets (first radio waves) and to measure a packet acquisition rate P and an index of stability of the field strength value. Here, the field strength value indicates the value of the field strength of the radio waves (each packet) received by the wireless communication unit 22 of the response terminal 20 from the radio wave measurement terminal 60. More specifically, the radio wave measurement terminal 60 may request the remaining response terminals 20 to measure the packet acquisition rate P and the maximum fluctuation width D1 of the average field strength value. Alternatively, the radio wave measurement terminal 60 may request the remaining response terminals 20 to measure the packet acquisition rate P and the maximum difference D2 between the average field strength value and the minimum field strength value.

[0209] After requesting reception of a plurality of packet sets, the radio wave measurement terminal 60 transmits the plurality of packet sets to the remaining response terminals 20. When the maximum fluctuation width D1 of the average field strength is requested as an index of the stability of the field strength value, the remaining response terminals 20 receive the plurality of packet sets (first radio waves) and measure the average field strength X, the packet acquisition rate P, and the maximum fluctuation width D1 of the average field strength. Alternatively, when the maximum difference D2 between the average field strength and the minimum field strength is requested as an index of the stability of the field strength value, the remaining response terminals 20 receive the plurality of packet sets (first radio waves) and measure the average field strength X, the minimum field strength Xmin, the packet acquisition rate P, and the maximum difference D2 between the average field strength and the minimum field strength.

[0210] After transmitting a plurality of packet sets, the radio wave measurement terminal 60 requests the remaining response terminals 20 to respond with the packet acquisition rate P and an index of the stability of the field strength value. As a result, the remaining response terminals 20 transmit a response signal (second radio wave) indicating the packet acquisition rate P and the index of the stability of the field strength value to the radio wave measurement terminal 60. Note that the remaining response terminals 20 may transmit a response signal (second radio wave) indicating the packet acquisition rate P and the index of the stability of the field strength value to the radio wave measurement terminal 60 in response to measuring the packet acquisition rate P and the index of the stability of the field strength value.

[0211] 1 to 26, the radio wave measurement terminal 60 selects a communication partner for the newly installed slave device 20A, but the newly installed slave device 20A may select a communication partner for the newly installed slave device 20A. In this case, the newly installed slave device 20A is an example of a radio wave measurement device and has a similar configuration to the radio wave measurement terminal 60. [Industrial Applicability]

[0212] The present invention provides a radio wave measuring device and has industrial applicability. [Explanation of symbols]

[0213] 20A: Newly installed handset 20f: Child unit 20h: Child unit 20i: Child unit 20j: Child unit 20k: Child unit 60: Radio wave measurement terminal 61: Processing section 62: Wireless communication unit 63: Storage section 64:Operation unit 65:Display section

Claims

1. A radio wave measuring device that selects one of a plurality of first wireless communication terminals as a communication partner of a second wireless communication terminal, a processing unit that selects one of the plurality of first wireless communication terminals as a communication partner of the second wireless communication terminal based on a plurality of selection conditions; the processing unit executes a determination process for determining whether or not to change the priority order set for each of the plurality of selection conditions; When the processing unit determines to change the priority order, the processing unit changes the priority order; the processing unit executes a condition selection process of selecting one of the plurality of selection conditions in accordance with the priority order, and a terminal selection process of selecting, from among the plurality of first wireless communication terminals, a wireless communication terminal that matches the selected selection condition as a communication partner of the second wireless communication terminal, a wireless communication unit that transmits a first radio wave and receives a second radio wave from each of the plurality of first wireless communication terminals; The processing unit includes: acquiring the number of the first wireless communication terminals based on the second radio wave; In the determination process, it is determined whether or not to change the priority order based on the number of the first wireless communication terminals; When it is determined to change the priority order, the radio wave measuring device changes the priority order based on the number of the first wireless communication terminals.

2. A radio wave measuring device that selects one of a plurality of first wireless communication terminals as a communication partner of a second wireless communication terminal, a processing unit that selects one of the plurality of first wireless communication terminals as a communication partner of the second wireless communication terminal based on a plurality of selection conditions; the processing unit executes a determination process for determining whether or not to change the priority order set for each of the plurality of selection conditions; When the processing unit determines to change the priority order, the processing unit changes the priority order; the processing unit executes a condition selection process of selecting one of the plurality of selection conditions in accordance with the priority order, and a terminal selection process of selecting, from among the plurality of first wireless communication terminals, a wireless communication terminal that matches the selected selection condition as a communication partner of the second wireless communication terminal, a wireless communication unit configured to transmit a first radio wave, receive a second radio wave from each of the plurality of first wireless communication terminals, and detect a field intensity of each of the second radio waves; The processing unit includes: In the determination process, it is determined whether or not to change the priority order based on the electric field strength; When it is determined to change the priority, the radio wave measuring device changes the priority based on the electric field strength.

3. A reception unit that receives an instruction to change the priority order from an operator is further provided, The processing unit includes: In the determination process, a determination is made as to whether or not to change the priority order depending on whether or not the reception unit has received the change instruction; The radio wave measuring device according to claim 1 , wherein when it is determined to change the priority order, the priority order is changed based on the change instruction.

4. 4. The radio wave measuring device according to claim 1, wherein the processing unit repeatedly executes the condition selection process and the terminal selection process until one of the plurality of first wireless communication terminals is selected as a communication partner of the second wireless communication terminal.

5. a wireless communication unit configured to transmit a first radio wave, receive a second radio wave from each of the plurality of first wireless communication terminals, and detect a field intensity of each of the second radio waves; The plurality of selection conditions include a first selection condition and a plurality of second selection conditions, The processing unit determines, in the determination process, whether or not to change the priority order set for each of the plurality of second selection conditions; the first selection condition is a selection condition that specifies selecting, from among the plurality of first wireless communication terminals, a wireless communication terminal having the electric field strength equal to or greater than a first reference value; The processing unit selects the first selection condition in the initial condition selection process, The radio wave measuring device according to claim 1 , wherein the processing unit selects one of the plurality of second selection conditions in accordance with the priority order in a second or subsequent condition selection process.

6. the second wireless communication terminal communicates with a third wireless communication terminal via one wireless communication terminal selected from the plurality of first wireless communication terminals as a relay terminal, or communicates directly with the third wireless communication terminal; the plurality of selection conditions include a selection condition that specifies selecting a wireless communication terminal having a smallest number of relay terminals from among the plurality of first wireless communication terminals; The radio wave measuring device according to claim 1 , wherein the number of relay terminals indicates the number of wireless communication terminals that are present as relay terminals between the first wireless communication terminal and the third wireless communication terminal.

7. the plurality of selection conditions include a selection condition that specifies selecting a wireless communication terminal having a smallest number of subordinate terminals from among the plurality of first wireless communication terminals; The radio wave measuring device according to claim 1 , wherein the number of subordinate terminals indicates the number of wireless communication terminals that communicate with a third wireless communication terminal using the first wireless communication terminal as a relay terminal.

8. a wireless communication unit that transmits a first radio wave and receives a second radio wave from each of the plurality of first wireless communication terminals; The radio wave measuring device according to any one of claims 1 to 7, wherein the plurality of selection conditions include a selection condition that specifies selecting, from among the plurality of first wireless communication terminals, a wireless communication terminal having the most stable electric field strength of the first radio wave or the most stable electric field strength of the second radio wave.

9. a wireless communication unit that transmits a first radio wave and receives a second radio wave from each of the plurality of first wireless communication terminals; the first radio wave or the second radio wave carries a plurality of packets; the plurality of selection conditions include a selection condition that specifies selecting, from the plurality of first wireless communication terminals, a wireless communication terminal having the highest packet acquisition rate of the first radio wave or the highest packet acquisition rate of the second radio wave; the packet acquisition rate of the first radio wave indicates the number of packets received by the first wireless communication terminal among the plurality of packets carried by the first radio wave; 9. The radio wave measuring device according to claim 1, wherein the packet acquisition rate of the second radio wave indicates the number of packets received by the wireless communication unit out of the plurality of packets carried by the second radio wave.

10. the plurality of selection conditions include a selection condition that specifies selecting, from the plurality of first wireless communication terminals, a wireless communication terminal having a number of peripheral terminals equal to or greater than a second reference value; The radio wave measuring device according to claim 1 , wherein the number of peripheral terminals indicates a number of wireless communication terminals capable of communicating with the first wireless communication terminal.

11. a wireless communication unit configured to transmit a first radio wave, receive a second radio wave from each of the plurality of first wireless communication terminals, and detect a field intensity of each of the second radio waves; 11. The radio wave measuring device according to claim 1, wherein the plurality of selection conditions include a selection condition that specifies that a wireless communication terminal having the strongest electric field strength is selected from among the plurality of first wireless communication terminals.

12. The radio wave measuring device according to claim 1 , wherein the radio wave measuring device is the second wireless communication terminal.

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