Communication device, communication system equipped with the same, communication method, and communication program

1 . A communication device that acquires an output signal from an external device and transmits it to an external server, the communication device comprising:

a first communication unit comprising a first antenna;

a second communication unit comprising a second antenna;

a processor configured with a program to perform operations comprising:

acquiring an output signal from the external device; and

operation as a first communication control unit configured to use the first communication unit to communicate with the external server to transmit the output signal to the external server when a radio field strength of the signal transmitted from the first communication unit to the external server is over a specific threshold value, and switch a subject of the communication from communication using the first communication unit to communication using the second communication unit to transmit the output signal to the external server when the radio field strength is at or below the specific threshold value.

2 . The communication device according to claim 1 ,

wherein the processor is configured with the program to perform operations further comprising operation as a second communication control unit configured to determine whether communication is possible according to whether the radio field strength of the signal transmitted from the second communication unit to the external server is over the specific threshold value.

3 . The communication device according to claim 2 ,

wherein the processor is configured with the program to perform operations such that operation as the second communication control unit determines whether communication is possible according to whether or not a response signal is received from the external server within a specific length of time when the output signal has been transmitted to the external server.

4 . The communication device according to claim 1 ,

wherein the processor is configured with the program to perform operations such that operation as the first communication control unit determines whether communication is possible according to whether or not a response signal is received from the external server within a specific length of time when the output signal has been transmitted to the external server.

5 . The communication device according to claim 1 ,

wherein the processor is configured with the program to perform operations such that operation as the first communication control unit uses RSSI (received signal strength indicator) or RSRP (reference signal received power) data as data for determination using radio field strength.

6 . The communication device according to claim 1 ,

wherein the first communication unit comprising the first antenna is configured to communicate with the external server by a first communication method, and

the second communication unit comprising the second antenna is configured to communicate with the external server by a second communication method that is different from the first communication method.

7 . The communication device according to claim 1 ,

further comprising a first storage that stores the output signal acquired.

8 . The communication device according to claim 7 ,

wherein the first storage stores the radio field strength of the signal transmitted from the first communication unit to the external server.

9 . The communication device according to claim 1 ,

further comprising a second storage configured to store the radio field strength of the signal transmitted from the second communication unit to the external server.

10 . The communication device according to claim 1 ,

wherein the external device includes a weather sensor configured to acquire weather data, a power monitoring sensor configured to acquire power information, or an agricultural sensor configured to acquire information from equipment used in agricultural cultivation.

11 . A communication system, comprising:

the communication device according to claim 1 ;

the external device configured to transmit the output signal to the communication device; and

the external server configured to receive the output signal transmitted via the communication device.

12 . A communication method that makes use of a communication device comprising first and second communication units respectively comprising first and second antennas that transmit output signals acquired from an external device to an external server, the communication method comprising:

acquiring an output signal from the external device; and

using the first communication unit to communicate with the external server to transmit the output signal to the external server when a radio field strength of the signal transmitted from the first communication unit to the external server is over a specific threshold value, and switching a subject of the communication from communication using the first communication unit to communication using the second communication unit to transmit the output signal to the external server when the radio field strength is at or below the specific threshold value.

13 . A communication program that is executed by a communication device comprising first and second communication units respectively comprising first and second antennas that transmit output signals acquired from an external device to an external server, the communication program causing a computer to execute a communication method comprising:

acquiring an output signal from the external device; and

using the first communication unit to communicate with the external server to transmit the output signal to the external server when a radio field strength of the signal transmitted from the first communication unit to the external server is over a specific threshold value, and switching a subject of the communication from communication using the first communication unit to communication using the second communication unit to transmit the output signal to the external server when the radio field strength is at or below the specific threshold value.