JP2014075627A - Communication line availability determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication line availability determination device capable of stabilizing determination of whether or not ship-ground communication lines having different communication line characteristics are available.SOLUTION: A communication line availability determination device 20 comprises: a communication line stability evaluation unit 21 for evaluating stability of communication quality of each of a plurality of ship-ground communication lines connecting a PC3 installed in a ship and a PC33 installed on the ground; and a communication line availability determination unit 22 for determining: that a ship-ground communication line is available, when stability of the ship-ground communication line is equal to or larger than a first threshold previously determined for each ship-ground communication line; and that a ship-ground communication line is not available, when stability of the ship-ground communication line is lower than the first threshold and equal to or smaller than a second threshold previously determined for each ship-ground communication line after it is determined that the ship-ground communication line is available.

Description

  The present invention relates to a communication line use determination device mounted in a ship-land communication system.

  In recent years, various communication systems have been constructed in accordance with social demands and progress in communication technology. One of them is a ship-land communication system. In this ship-land communication system, a ship-land communication line (hereinafter simply referred to as a communication line) is provided between a device (for example, a personal computer (PC)) placed on the ship and a device (eg, a PC) placed on land. In some cases, data communication such as audio and video is possible. Even in such a ship-land communication system, in order to use a more optimal ship-land communication line, it is possible to switch from the ship-land communication line in use to another ship-land communication line. Yes.

  The present inventor extracted the following prior art documents as a result of conducting a prior art literature search in the process of making the present invention.

  Patent Document 1 discloses a wireless terminal device capable of automatically switching a connection-destination wireless communication system according to application contents, communication state, user state, surrounding environment state, and the like. ing.

JP 2002-112347 A

  By the way, in the ship-land communication system, when switching the ship-land communication line, it is necessary to determine whether or not the switching-destination ship-land communication line can be used. In addition, since the ship-land communication system is susceptible to communication failures due to ship movement and weather changes, it is necessary to determine whether the communication quality of the ship-land communication line is stable enough to withstand actual use. .

  Therefore, as the use judgment of the ship-land communication line, the stability of the communication quality of the ship-land communication line is evaluated, and when the evaluated stability exceeds a predetermined threshold value, it is determined that it can be used. In such a case, a method of determining that it cannot be used can be considered.

  However, in the past, since it was determined whether the ship-land communication line can be used or not based on one threshold value, the frequency of repeating the determination to be usable and the determination to be unusable increases. There is a problem that the use judgment of the ship-land communication line becomes unstable.

  An object of the present invention is to provide a communication line use determination device capable of stabilizing the determination of whether a ship-land communication line having different communication line characteristics can be used or not.

  The communication line use determination device according to the present invention is (1) whether or not each of a plurality of ship-land communication lines connecting between a device installed on a ship and a device installed on the ground is usable or not. A communication line usage determining device for determining the stability of communication quality of the ship-land communication line, and the stability is predetermined for each ship-land communication line. It is determined that a ship-land communication line that is equal to or greater than a threshold value of 1 can be used, and the stability is lower than the first threshold value after the use is determined to be possible, and is determined in advance for each ship-land communication line. Use determination means for determining that the use of the ship-land communication line that is equal to or lower than the second threshold value is impossible.

  With this configuration, the communication line use determination device according to the present invention determines whether the use of the communication line between the ship and the land is possible or not based on the first and second threshold values provided with a certain level difference. Compared with the case where it is determined whether or not the use of the communication line between the ship and the land is possible based on one threshold value, the determination as to whether or not the use of the communication line is possible can be stabilized.

  A communication line usage determining apparatus according to the present invention is the communication line usage determining apparatus according to (1), wherein (2) the stability evaluation means stepwise increases the stability in units of predetermined time units. The stability is increased on the condition that the communication quality of the inter-ship communication line is stable within the predetermined time unit, and the ship-land communication is performed within the predetermined time unit. The stability is lowered on condition that the communication quality of the communication line is not stable.

  With this configuration, the communication line usage determining apparatus according to the present invention raises and lowers the stability in stages, so that the accuracy of the stability can be increased.

  ADVANTAGE OF THE INVENTION According to this invention, the communication line utilization determination apparatus which can stabilize determination of whether the utilization of a ship-land communication line is possible or impossible can be provided.

It is a block diagram which shows the structure of the ship-land communication system in embodiment of this invention. It is a figure which shows the threshold value of the communication network in embodiment of this invention. It is function explanatory drawing of the communication line stability evaluation part and communication line utilization determination part in embodiment of this invention. It is a flowchart which shows the determination procedure of the communication line utilization determination apparatus in embodiment of this invention. It is a flowchart which shows the procedure of communication line stability evaluation and communication line utilization determination.

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

  First, the structure of the ship-land communication system in this embodiment is demonstrated.

  As shown in FIG. 1, an inter-ship communication system 1 in this embodiment includes an in-board communication network 2, a ship-side PC 3, a ship-mounted communication device 10, the Internet 30, a land-side PC 33, a satellite communication network 40, and a mobile phone. A network 50 is provided. The satellite communication network 40 includes a communication satellite 41 and a satellite base station 42, and the mobile phone network 50 includes a mobile phone base station 51.

  In the following description, an example of performing a voice call between the PC 3 and the PC 33 in the ship-land communication system 1 will be described.

  The PC 3 includes, for example, hardware such as a microphone, a speaker, and an audio signal processing circuit, and software for performing audio communication, and is connected to the onboard communication device 10 via the inboard communication network 2.

  The ship-mounted communication device 10 includes a satellite communication unit 11, a land communication unit 12, a communication line switching unit 13, and a communication line use determination device 20. Although not shown, the ship-mounted communication device 10 includes a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and is stored in advance in the ROM. It works according to the program.

  The satellite communication unit 11 communicates with the PC 33 via a communication line including the satellite communication network 40 and the Internet 30 to which the satellite communication network 40 is connected. That is, a communication satellite 41 (for example, Inmarsat satellite) and a satellite base station 42 of the satellite communication network 40 and the Internet 30 are provided between the satellite communication unit 11 and the PC 33. The satellite communication unit 11 communicates with the PC 33 by entering the satellite communication network 40.

  The land communication unit 12 communicates with the PC 33 via a communication line including a mobile phone network 50 and the Internet 30 to which the mobile phone network 50 is connected. That is, a mobile phone base station 51 of the mobile phone network 50 and the Internet 30 are provided between the land communication unit 12 and the PC 33. In addition, the land communication unit 12 communicates with the PC 33 by entering the mobile phone network 50.

  Here, a communication network that enables the satellite communication unit 11 and the land communication unit 12 to communicate is, for example, as shown in FIG. That is, the satellite communication unit 11 can communicate with the satellite communication networks of Company A and Company B. Further, the land communication unit 12 can communicate with the mobile phone networks of the C company and the D company, and the wireless LANs (Local Area Networks) of the E company, the F company, and the G company that comply with the IEEE 802.11 standard. The ship-mounted communication device 10 enables communication between ship and land by selecting and entering any one of these communication networks.

  Since the communication line includes a communication network, the use of the communication line can be determined by determining the use of the communication network. Therefore, in the following description, the satellite communication network 40 and the mobile phone network 50 are used as objects of use determination.

  The communication line switching unit 13 is connected to the PC 3 via the inboard communication network 2 and receives a packet output from the PC 3. In addition, the communication line switching unit 13 determines which one of the communication networks stored as a communication line selection candidate in the communication line selection candidate storage unit 24, which will be described later, according to a predetermined priority (for example, communication speed, billing mode, etc.). It is determined whether to use the communication network, and the communication network is connected or switched.

  The communication line usage determination device 20 includes a communication line stability evaluation unit 21, a communication line usage determination unit 22, a threshold storage unit 23, and a communication line selection candidate storage unit 24. This communication line usage determining device 20 is for determining whether a communication network in which the satellite communication unit 11 and the land communication unit 12 can communicate has stability enough to withstand actual use.

  The communication line stability evaluation unit 21 evaluates the stability of the communication quality of the communication network that the satellite communication unit 11 and the land communication unit 12 can communicate with, and transmits the evaluated stability data to the communication line use determination unit 22. To do.

  As will be described in detail later, the communication line stability evaluation unit 21 evaluates the stability step by step for each predetermined time unit. The communication line stability evaluation unit 21 determines the communication network to be evaluated within a predetermined time unit. Increase the stability by one level on the condition that the communication quality is stable, and decrease the stability by one level on the condition that the communication quality of the communication network to be evaluated is not stable within a predetermined time unit It is. The communication line stability evaluation unit 21 constitutes stability evaluation means according to the present invention.

  The communication line usage determination unit 22 determines whether or not the communication network evaluated by the communication line stability evaluation unit 21 can be actually used. When the communication line usage determining unit 22 determines that the communication network is usable, the communication line usage determining unit 22 transmits a registration signal for registering the communication network as a communication line selection candidate to the communication line selection candidate storage unit 24 and determines that the communication line usage determining unit 22 cannot use the communication network. Transmits an exclusion signal for excluding the communication network from the communication line selection candidates to the communication line selection candidate storage unit 24. The communication line usage determining unit 22 constitutes a usage determining unit according to the present invention.

  The threshold storage unit 23 is configured to store data set in advance for a communication network that allows the satellite communication unit 11 and the land communication unit 12 to communicate. The data includes an entry threshold value, an exit threshold value, an upper limit value, and the like related to the stability of the communication quality of the communication network. The entry threshold is a threshold for determining whether or not the communication network can be entered, that is, whether or not the communication network is available. The leaving threshold is a threshold value for determining whether or not to leave the communication network after it is determined that it can be used, that is, whether or not the communication network can be used after it is determined that it can be used. The upper limit value is a predetermined upper limit value for the stability of the communication network. These data are set for each communication network in accordance with the characteristics of the communication network.

  The communication line selection candidate storage unit 24 stores, as communication line selection candidates, communication lines that are determined to be usable based on the registration signal transmitted from the communication line use determination unit 22. Further, the communication line selection candidate storage unit 24 is configured to exclude the corresponding communication network from the communication line selection candidates based on the exclusion signal transmitted from the communication line usage determination unit 22.

  Next, functions of the communication line stability evaluation unit 21 and the communication line use determination unit 22 will be specifically described with reference to FIG.

  FIG. 3 shows the stability of the communication quality of the communication network in stages. The horizontal axis in the figure is a constant time passage, and continuously represents 1 minute as a time unit. For example, time unit 1 is a constant from time 0 to 1 minute, and time unit 2 is a constant from time 1 minute to 2 minutes. The vertical axis in the figure represents the stability of the communication quality of the communication network.

  In FIG. 3, the departure threshold value, the entry threshold value, and the upper limit value are exemplified as those of the satellite communication network 40 that is predetermined and stored in the threshold value storage unit 23.

  First, the function of the communication line stability evaluation unit 21 will be described.

  The communication line stability evaluation unit 21 sets the stability of the communication quality of the satellite communication network 40 to be evaluated to 0 at the start of evaluation.

  The communication line stability evaluation unit 21 sends a response request packet including, for example, a Ping command from the satellite communication unit 11 or the land communication unit 12 to the PC 33 via the satellite communication network 40 to be evaluated. It is determined whether the satellite communication unit 11 has received a response confirmation packet for the packet from the PC 33. The response request packet is transmitted at a rate of once in a time unit, for example.

  Further, the communication line stability evaluation unit 21 increases the stability by one step when it is determined that the satellite communication unit 11 has received the response confirmation packet, and thereafter stabilizes stepwise according to the number of times the response confirmation packet is received. Increase the degree. Here, when the stability is 0, the stability is increased by one step from 0 to the stability 1, and thereafter, the stability is increased stepwise according to the number of times the response confirmation packet is received.

  In addition, when the stability reaches the upper limit value, the communication line stability evaluation unit 21 maintains the stability at the upper limit value even if a response confirmation packet is received thereafter.

  Further, when the communication line stability evaluation unit 21 determines that the satellite communication unit 11 has not received the response confirmation packet, the communication line stability evaluation unit 21 decreases the stability by one step, and thereafter, depending on the number of times the response confirmation packet has not been received. The stability is gradually lowered. Here, even when the response confirmation packet is not received when the stability is 0, the stability 0 is maintained.

  That is, as described above, the communication line stability evaluation unit 21 evaluates the stability step by step for each predetermined time unit, and the communication quality of the communication line to be evaluated is determined within a predetermined time unit. The stability is increased by one step on the condition that it is stable, and the stability is decreased by one step on the condition that the communication quality of the communication line to be evaluated is not stable within a predetermined time unit.

  In the present embodiment, an example is given in which response request packets are sent once per time unit. In this case, the stability is increased by one step by receiving one response confirmation packet for one response request packet, and one response confirmation packet for one response request packet cannot be received. Decrease stability by one step. On the other hand, when a response request packet is sent at a rate of multiple times within a time unit, the stability is increased by one level by receiving all response confirmation packets corresponding to the multiple response request packets. It is preferable that the stability is lowered by one step because all of the response confirmation packets corresponding to one response request packet could not be received.

  In this embodiment, the stability is increased by one step and decreased by one step. However, the stability may be increased or decreased by several steps according to the characteristics of the communication line.

  In this embodiment, an example of sending a response request packet is given, but it goes without saying that the stability can be raised or lowered by other means (for example, a measurement result of a bit error rate or electric field strength of a communication line). Also good.

  Next, the function of the communication line usage determining unit 22 will be described.

  The communication line usage determination unit 22 sets the satellite communication network 40, whose communication quality stability has been evaluated by the communication line stability evaluation unit 21 in the previous stage, as the determination target, and the entry threshold value and the leaving threshold value of the satellite communication network 40 as the determination target. Is read from the threshold storage unit 23. The communication line usage determination unit 22 determines that the satellite communication network 40 can be used (can enter) when the stability of the satellite communication network 40 to be determined is equal to or greater than the entry threshold, and after it is determined that the satellite communication network 40 can be used. When the stability of the satellite communication network 40 to be determined is equal to or less than the retreat threshold, it is determined that the satellite communication network 40 cannot be used (participation is impossible, retreat). The entry threshold value is larger than the exit threshold value, and a certain level difference is provided between them. In the example of FIG. 3, the entry threshold is 6 and the departure threshold is 3. That is, the communication line usage determination unit 22 determines whether or not the satellite communication network 40 can be used (can enter or cannot enter) based on two threshold values (entry threshold value and leaving threshold value) provided with a certain level difference. Is determined.

  Here, the use determination of the satellite communication network 40 will be described.

  In FIG. 3, the time unit 0 is an initial setting, so the stability is 0.

  The stability in the time units 1, 2, and 3 is 1, 2, and 3 respectively, and since the entry threshold is 6 or less, the satellite communication network 40 at this time is determined to be unusable (no entry).

  The stability in the time units 4 and 5 is 4 and 5 respectively, both being smaller than the entry threshold 6 and before being determined to be usable (before being determined to be able to enter), the satellite at this time It is determined that the communication network 40 cannot be used (cannot enter).

  The stability in the time units 6, 7, and 8 is 6, 7, and 8 respectively, and since the entry threshold is 6 or more, it is determined that the satellite communication network 40 at this time can be used.

  Although the stability in the time unit 9 is 5 and smaller than the entry threshold 6, it is determined that the satellite communication network 40 at this time can be used because it is determined that it can be used.

  The stability in the time units 10 to 13 is 6 to 9, respectively, and since both are more than the entry threshold value 6, it is determined that the satellite communication network 40 at this time can be used.

  Since the stability in the time units 14 to 16 is the upper limit value 10 and each is equal to or greater than the entry threshold value 6, it is determined that the satellite communication network 40 at this time can be used.

  The stability in the time units 17 to 20 is 9 to 6, respectively, and since both are more than the entry threshold value 6, it is determined that the satellite communication network 40 at this time can be used.

  The stability in the time units 21 and 22 is 5 and 4 respectively, both of which are lower than the entry threshold 6, but since it is determined that it can be used, the satellite communication network 40 at this time is determined to be usable. .

  The stability of the time units 23 to 25 is 3 to 1, respectively, which are all equal to or less than the retreat threshold 3, and after it has been determined that it can be used, the satellite communication network 40 at this time cannot be used (cannot enter, Evacuation).

  To summarize the above determination, the communication line usage determination unit 22 (1) determines that the satellite communication network 40 is available (can be entered) when the stability is equal to or greater than the entry threshold, and (2) is determined to be available. After that, when the stability is equal to or less than the withdrawal threshold, it is determined that the satellite communication network 40 cannot be used (cannot enter, leave).

  From the determinations of (1) and (2) above, whether or not the satellite communication network 40 can be used based on two threshold values (entry threshold value and leaving threshold value) provided with a certain level difference (whether or not to enter). ) To determine whether the use of the satellite communication network 40 is possible or impossible based on one threshold value, and the frequency at which the determination that the use is possible and the determination that the use is not possible are repeated. Can be suppressed, and the determination of whether or not the communication line can be used can be stabilized.

  Note that the communication line usage determining device 20 executes the same processing as that of the satellite communication network 40 for the mobile phone network 50.

  Next, the operation of the ship-land communication system 1 in this embodiment will be described using the flowcharts shown in FIGS. 4 and 5 with reference to the block configuration diagram shown in FIG.

  In the following description of the operation, an example of determining whether or not any communication network can be used when both the satellite communication network 40 and the cellular phone network 50 are not connected as communication lines will be described. . Further, as described above, the response request packet is transmitted at a rate of once in a time unit of one minute.

  In FIG. 4, the communication line usage determining device 20 performs processing for evaluating the stability of communication quality with respect to the satellite communication network 40, and performs processing for determining whether or not the evaluated satellite communication line can be used. (Step S10).

  Details of step S10 will be described with reference to FIG.

  The communication line stability evaluation unit 21 initializes a variable i representing the stability of the communication quality of the satellite communication network 40 to be evaluated (step S11). That is, the variable i is set to 0.

  The communication line stability evaluation unit 21 outputs a control signal to the satellite communication unit 11 so as to transmit a response request packet to the PC 33 via the satellite communication network 40 to be evaluated, and the satellite communication unit 11 transmits the response request packet. (Step S12).

  The communication line stability evaluation unit 21 determines whether the satellite communication unit 11 has received a response confirmation packet for the response request packet (step S13).

  In step S13, when the communication line stability evaluation unit 21 determines that the satellite communication unit 11 has not received a response confirmation packet (no reception), it subtracts 1 from the variable i (step S14).

  The communication line stability evaluation unit 21 determines whether or not the variable i is negative (step S15).

  In step S15, if the variable i is negative (YES), the communication line stability evaluation unit 21 substitutes 0 for the variable i (step S16), and proceeds to step S21 described later. If the variable i is not negative (NO), the communication line stability evaluation unit 21 proceeds to step S21 described later.

  In step S13, when the communication line stability evaluation unit 21 determines that the satellite communication unit 11 has received the response confirmation packet (with reception), 1 is added to the variable i (step S17).

  The communication line stability evaluation unit 21 determines whether or not the variable i is equal to or greater than a predetermined upper limit value for the satellite communication network 40 to be evaluated (step S18).

  In step S18, if the variable i is greater than or equal to the upper limit value (YES), the communication line stability evaluation unit 21 substitutes the upper limit value for the variable i (step S19), and proceeds to step S21 described later.

  The communication line usage determining unit 22 reads data of the leaving threshold predetermined for the satellite communication network 40 to be determined from the threshold storage unit 23, and determines whether or not the variable i is equal to or less than the leaving threshold (step S21). .

  In step S21, the communication line usage determining unit 22 indicates the size of the variable i with respect to the leaving threshold when the variable i is equal to or less than a predetermined leaving threshold for the satellite communication line to be determined (YES). The retreat flag is turned on (step S22).

  When the satellite communication network 40 that is the target of the turn-off flag turned on is registered in the communication line selection candidate storage unit 24 as a communication line selection candidate, the communication line usage determination unit 22 stores the communication line selection candidate storage unit 24. An exclusion signal for exclusion from the communication line selection candidates is transmitted to the communication line selection candidate storage unit 24, and is excluded from the communication line selection candidates in the communication line selection candidate storage unit 24 (step S23).

  In step S21, when the variable i is larger than a predetermined exit threshold for the satellite communication line to be determined (NO), the communication line usage determining unit 22 determines the predetermined value for the satellite communication line to be determined. The entry threshold data is read out from the threshold storage unit 23, and it is determined whether or not the variable i is equal to or greater than the entry threshold (step S24).

  In step S24, when the variable i is equal to or greater than the entry threshold (YES), the entry flag indicating the size of the variable i with respect to the entry threshold is turned on (step S25).

  The communication line usage determination unit 22 transmits a registration signal for registering the satellite communication network 40 that is the target of the entry flag that is turned on as a communication line selection candidate to the communication line selection candidate storage unit 24, and stores the communication line selection candidate storage. The satellite communication network 40 is registered in the unit 24 as a communication line selection candidate (step S26).

  In step S24, when the variable i is smaller than a predetermined entry threshold for the communication line to be determined (NO), the entry flag is turned off (step S27), and the leaving flag is turned off (step S28). That is, the communication line selection candidate storage unit 24 is not registered or excluded as a communication line selection candidate for the satellite communication line to be determined.

  The communication line usage determining unit 22 performs the process of returning to step S12 and the process of proceeding to step 30 described later after processing step S23, step S26, and step S28.

  Whether the communication line usage determination device 20 can perform the same processing as the satellite communication network 40 on the mobile phone network 50, that is, the processing for evaluating the stability of the communication quality and the use of the evaluated mobile phone network 50. Or the process which determines whether it is impossible is performed (step S10). In this case, transmission of a response request packet and reception of a response confirmation packet for the response request packet are performed via the land communication unit 12.

  Here, referring back to FIG. 4, the communication line switching unit 13 selects which communication network from the communication line selection candidates stored in the communication line selection candidate storage unit 24 according to the priority (for example, communication speed, billing form, etc.). Is used (step S30).

  In step S30, the communication line switching unit 13 selects the satellite communication network 40 when using the satellite communication network 40 (step S31). When the communication line switching unit 13 selects the satellite communication network 40, the ship-land communication system 1 performs audio streaming between the ship side PC 3 and the land side PC 33 via the communication line including the satellite communication network 40. Packets are transmitted and received (step S33).

  In step S30, the communication line switching unit 13 selects the cellular phone network 50 when using the cellular phone network 50 (step S32). When the communication line switching unit 13 selects the mobile phone network 50, the ship-land communication system 1 performs audio streaming between the ship side PC 3 and the land side PC 33 via the communication line including the mobile phone network 50. Packets are transmitted and received (step S33).

  As described above, the inter-ship communication system 1 in the present embodiment is a communication line (satellite communication network 40 or mobile phone network 50) that connects between the PC 3 arranged on the ship and the PC 33 arranged on land. It has a communication line usage determining device 20 that determines whether it can be used or not. The communication line usage determination device 20 can use a communication line (satellite communication network 40 or mobile phone network 50) based on an entry threshold value and a departure threshold value (first and second threshold values) provided with a certain level difference. Therefore, the communication line (satellite communication) is compared with the case where it is determined whether or not the communication line (satellite communication network 40 or the mobile phone network 50) can be used based on one threshold value. The determination of whether or not the network 40 or the mobile phone network 50) can be used can be stabilized.

  Moreover, since the communication line usage determining device 20 raises and lowers the stability in stages, the accuracy of the stability can be increased.

  In the above-described embodiment, (a) as a method for evaluating the stability of communication quality of a communication line, an example is described in which a response request packet including a Ping command is sent to the communication line to be evaluated. However, as a method of evaluating the stability of the communication quality of the communication line, for example, a method of evaluating the stability of the communication quality of the communication line by measuring BER (Bit Error Rate) may be used.

  In the above-described embodiment, (a) in the inter-ship communication system 1, the audio streaming packet has been described as an example of the packet transmitted between the ship-side PC 3 and the ground-side PC 33. It may be a packet other than a packet.

  In the above-described embodiment, (c) the two communication networks of the satellite communication network 40 and the mobile phone network 50 are mainly described as examples. However, the present invention is not limited to this, The present invention can be applied to any communication network in which the satellite communication unit 11 and the land communication unit 12 can communicate, and the present invention can also be applied to three or more communication networks.

  In these cases (a) to (c), the communication line use determination device 20 can stabilize the determination of whether or not the communication line can be used, as in the above-described embodiment. In addition, the communication line usage determining device 20 can increase the accuracy of stability.

  As described above, the communication line use determination device according to the present invention has an effect of stabilizing the determination of whether the use of the ship-land communication line is possible or not, and is installed in the ship-land communication system. This is useful as a communication line usage determination device.

1 Communication system between ship and land 2 Inboard communication network 3, 33 PC
DESCRIPTION OF SYMBOLS 10 Shipboard communication apparatus 11 Satellite communication part 12 Land communication part 13 Communication line switching part 20 Communication line utilization determination apparatus 21 Communication line stability evaluation part (stability evaluation means)
22 Communication line usage judgment unit (usage judgment means)
23 Threshold Storage Unit 24 Communication Line Selection Candidate Storage Unit 30 Internet 40 Satellite Communication Network 41 Communication Satellite 42 Satellite Base Station 50 Cellular Phone Network 51 Cellular Phone Base Station

Claims (2)

A communication line usage determination device that determines whether each of a plurality of ship-land communication lines connecting between a device installed on a ship and a device installed on the ground is usable or not,
Stability evaluation means for evaluating the stability of the communication quality of the ship-land communication line;
It is determined that the use of a ship-land communication line whose stability is equal to or greater than a first threshold value predetermined for each ship-land communication line is possible, and the stability is determined after the use is determined to be possible. Use determination means for determining that the use of a ship-land communication line that is lower than a threshold value of 1 and is equal to or less than a second threshold value that is predetermined for each ship-land communication line;
A communication line usage determining apparatus comprising: The communication line usage determination device according to claim 1,
The stability evaluation means evaluates the stability in stages for each predetermined time unit, and the communication quality of the ship-land communication line is stable within the predetermined time unit. The communication line is characterized in that the stability is increased under conditions, and the stability is decreased under the condition that the communication quality of the ship-land communication line is not stable within the predetermined time unit. Usage determination device.

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