Ship information exchange device, ship information exchange method, and ship information exchange program

Abstract

To reduce a processing load of demodulation processing.SOLUTION: A ship information exchange device includes a receiving unit that receives a wireless signal, a generation unit that generates received data of a plurality of channels used for transmitting ship information from the wireless signal, a detection unit that detects the reception level of each of the channels, and a demodulation unit that demodulates the received data, and the demodulation unit determines the received data to be demodulated according to a result of detecting the reception level.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a ship information exchange device, a ship information exchange method, and a ship information exchange program. [Background technology]

[0002] Conventionally, there is known a technique for transmitting and receiving ship information such as ship identification codes between ships. The ship information is transmitted and received using a channel in a predetermined frequency band, and is demodulated by a receiving device. Summary of the Invention [Problem to be solved by the invention]

[0003] However, with conventional technology, the processing load of the demodulation process on the device that receives the ship information increases, and data loss may occur due to the demodulation process not being completed in time.

[0004] This invention has been made to solve the above-mentioned problems, and its purpose is to provide a ship information exchange device, a ship information exchange method, and a ship information exchange program that can reduce the processing load of demodulation processing. [Means for solving the problem]

[0005] (1) In order to solve the above problem, a ship information exchange device according to one aspect of the present invention comprises a receiving unit that receives a radio signal, a generating unit that generates received data of multiple channels used for transmitting ship information from the radio signal, a detecting unit that detects the receiving level of each of the channels, and a demodulating unit that demodulates the received data, and the demodulating unit determines the received data to be demodulated based on the detection result of the receiving level.

[0006] In this way, the configuration that determines the received data to be demodulated according to the reception levels of multiple channels allows selective demodulation of received data that includes ship information, compared to a configuration that sequentially and repeatedly demodulates the received data contained in the radio signals of all channels in a time-division manner, regardless of whether the radio signals contain ship information. This suppresses an increase in the processing load caused by demodulating received data that does not contain ship information, and makes it possible to speed up the response of various processes in the demodulation unit. As a result, the processing load of the demodulation process can be reduced, and the processing costs and production costs for performing the demodulation can be reduced.

[0007] (2) The demodulation unit may determine the number of channels used to transmit the ship information based on the detection result, and determine the received data to be demodulated based on the determination result.

[0008] (3) The detection unit may further detect the reception level at a boundary frequency between the adjacent channels.

[0009] (4) The demodulation unit may demodulate the received data of the first channel when the receiving level of the first channel is equal to or greater than a predetermined value and the receiving level at the boundary frequency between the first channel and the channel adjacent to the first channel is less than a predetermined value.

[0010] (5) When the reception levels of the first and second channels, which are channels of a continuous frequency band, are equal to or greater than a predetermined value and the reception levels at the boundary frequency between the first and second channels are less than a predetermined value, the demodulation unit may demodulate the reception data of the first channel and the reception data of the second channel, respectively.

[0011] (6) When the reception levels of the first and second channels, which are channels of a continuous frequency band, are equal to or greater than a predetermined value, and the reception level at the boundary frequency between the first and second channels is equal to or greater than a predetermined value, the demodulation unit may demodulate composite data obtained by combining the reception data of the first and second channels.

[0012] (7) The demodulation unit may demodulate composite data obtained by combining the received data of each of the channels of the plurality of consecutive frequency bands when the receiving level of each of the channels of the plurality of consecutive frequency bands is equal to or greater than a predetermined value and the receiving level at each boundary frequency of the adjacent channels is equal to or greater than a predetermined value.

[0013] (8) The demodulation unit may determine the received data to be demodulated based on a comparison result between the receiving level of the channel and a first threshold, and a comparison result between the receiving level at the boundary frequency and a second threshold different from the first threshold.

[0014] (9) The vessel information may include at least one of the vessel identification code, vessel name, vessel position, vessel course, vessel speed, and vessel destination.

[0015] (10) In order to solve the above problem, a ship information exchange method according to one aspect of the present invention is a ship information exchange method in a ship information exchange device, which receives a radio signal, generates received data of multiple channels used to transmit ship information from the radio signal, detects the receiving level of each of the channels, determines the received data to be demodulated based on the detection result of the receiving level, and demodulates the received data to be demodulated.

[0016] (11) In order to solve the above problem, a ship information exchange program according to a certain aspect of the present invention performs the following processes: receiving a radio signal; generating received data for multiple channels used to transmit ship information from the radio signal; detecting the receiving level of each of the channels; determining the received data to be demodulated based on the detection result of the receiving level; and demodulating the received data to be demodulated. [Effects of the Invention]

[0017] According to the present invention, the processing load of the demodulation process can be reduced. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing the configuration of a ship information exchange system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the configuration of a ship information exchange device according to an embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing an example of a frequency spectrum generated by a detection unit in the ship information exchange device according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing another example of a frequency spectrum generated by the detection unit in the ship information exchange device according to the embodiment of the present invention. [Figure 5] FIG. 5 is a diagram showing another example of a frequency spectrum generated by the detection unit in the ship information exchange device according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing an example of a comparison result notified to a processing unit by a detection unit in the ship information exchange device according to the embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing another example of the comparison result notified to the processing unit by the detection unit in the ship information exchange device according to the embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing another example of the comparison result notified to the processing unit by the detection unit in the ship information exchange device according to the embodiment of the present invention. [Figure 9] FIG. 9 is a diagram showing another example of the comparison result notified to the processing unit by the detection unit in the ship information exchange device according to the embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing another example of the comparison result notified to the processing unit by the detection unit in the ship information exchange device according to the embodiment of the present invention. [Figure 11] FIG. 11 is a flowchart illustrating an example of an operation performed by the ship information exchange device according to the embodiment of the present disclosure when demodulating received data. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any manner.

[0020] [Configuration and basic operation] <Ship Information Exchange System> Fig. 1 is a diagram showing the configuration of a ship information exchange system according to an embodiment of the present invention. Referring to Fig. 1, the ship information exchange system 201 includes a plurality of ship information exchange devices 101. Fig. 1 shows ship information exchange devices 101A, 101B, 101C, and 101D as representative ship information exchange devices 101. The ship information exchange system 201 may be configured to include two, three, five or more ship information exchange devices 101.

[0021] The vessel information exchange device 101 is provided on the vessel 1 or a land station. For example, the vessel information exchange device 101A is provided on the vessel 1A, the vessel information exchange device 101B is provided on the vessel 1B, the vessel information exchange device 101C is provided on the vessel 1C, and the vessel information exchange device 101D is provided on the land station. The vessel information exchange device 101 is, for example, an AIS (Automatic Identification System).

[0022] A ship information exchange device 101 installed on a ship 1 periodically or irregularly transmits a radio signal including ship information of the ship 1 to other ship information exchange devices 101. For example, the ship information includes at least one of the ship's identification code, ship name, ship's position, ship's course, ship's speed, and ship's destination.

[0023] More specifically, the ship information exchange devices 101A, 101B, and 101C generate modulated data by modulating communication data including ship information according to, for example, BPSK (Binary Phase Shift Keying), and transmit radio signals including the generated modulated data. Note that the ship information exchange devices 101A, 101B, and 101C may be configured to use other modulation methods, such as QPSK (Quadrature PSK), 8PSK, and 16QAM (Quadrature Amplitude Modulation), instead of BPSK.

[0024] The ship information exchange device 101 receives a radio signal from another ship information exchange device 101 installed on the ship 1 and acquires modulated data from the received radio signal. The ship information exchange device 101 generates communication data by demodulating the acquired modulated data and acquires ship information from the generated communication data. The ship information exchange device 101 notifies the user of information such as the identification code of the ship 1 indicated in the acquired ship information.

[0025] The ship information exchange device 101 transmits and receives radio signals using multiple channels in predetermined frequency bands. As an example, the ship information exchange device 101 transmits and receives radio signals using six channels CH1 to CH6.

[0026] For example, the ship information exchange devices 101A, 101B, and 101C transmit radio signals using channels CH1, CH2, and CH3, respectively, out of the six channels.

[0027] In this case, the ship information exchange devices 101B, 101C, and 101D receive the radio signal on channel CH1 transmitted by the ship information exchange device 101A. Also, the ship information exchange devices 101A, 101C, and 101D receive the radio signal on channel CH2 transmitted by the ship information exchange device 101B. Also, the ship information exchange devices 101A, 101B, and 101D receive the radio signal on channel CH3 transmitted by the ship information exchange device 101C.

[0028] <Issues> For example, when the distance between the ship information exchange device 101 and another ship information exchange device 101 mounted on a ship 1 other than the ships 1A, 1B, and 1C becomes less than a predetermined value, the ship information exchange device 101 further receives a radio signal transmitted by the other ship information exchange device 101. The ship information exchange device 101 may also switch the channel of the radio signal it transmits.

[0029] Furthermore, in the ship information exchange system 201, random access wireless communication is performed by the ship information exchange devices 101. That is, the order in which the ship information exchange devices 101 installed on each ship 1 transmit wireless signals is not predetermined, and each ship information exchange device 101 transmits a wireless signal at its own individual transmission timing.

[0030] Therefore, in the conventional ship information exchange device 101, regardless of whether the received radio signal contains ship information or not, it was necessary to perform the demodulation process of the six received data contained in each of the six channel radio signals sequentially and repeatedly in a time-division manner.

[0031] Furthermore, the ship information exchange device 101 may transmit a radio signal using a composite channel obtained by combining a plurality of channels in a continuous frequency band, depending on the content of the ship information to be transmitted.

[0032] Therefore, in the conventional ship information exchange device 101, in addition to demodulating the six pieces of received data contained in each of the six channel radio signals, it was necessary to further demodulate the received data contained in the corresponding radio signal for each combination of multiple channels in consecutive frequency bands.

[0033] Therefore, in the conventional ship information exchange device 101, the processing load of the demodulation process becomes large, and data loss may occur due to the demodulation process not being completed in time.

[0034] The vessel information exchange device 101 according to the embodiment of the present invention solves the above problems by using the following configuration.

[0035] <Ship information exchange device> Fig. 2 is a diagram showing the configuration of a ship information exchange device according to an embodiment of the present invention. Referring to Fig. 2, the ship information exchange device 101 includes a receiving unit 10, a generating unit 20, a detecting unit 30, a storage unit 40, and a processing unit 50. The processing unit 50 is an example of a demodulating unit. For example, the detecting unit 30 is connected to the processing unit 50 via eleven signal lines SL1 to SL11. Hereinafter, each of the signal lines SL1 to SL11 will also be referred to as a signal line SL.

[0036] A part or all of the generating unit 20 is realized by, for example, an FPGA (Field-Programmable Gate Array). A part or all of the detecting unit 30 and the processing unit 50 is realized by, for example, a processor such as a CPU (Central Processing Unit) and a DSP (Digital Signal Processor). The storage unit 40 is, for example, a RAM (Random Access Memory) and includes memory areas 41_1 to 41_11.

[0037] The receiving unit 10 includes an antenna 11 and an amplifier 12 .

[0038] The generation unit 20 includes a mixer 21, an AD (Analog to Digital) conversion unit 22, filter units 23_1 to 23_11, and transfer units 24_1 to 24_11. Hereinafter, each of the filter units 23_1 to 23_11 will also be referred to as a filter unit 23, and each of the transfer units 24_1 to 24_11 will also be referred to as a transfer unit 24. The transfer units 24 are realized by, for example, DMA (Direct Memory Access).

[0039] (Receiver) The receiving unit 10 receives the radio signals. More specifically, the amplifier 12 amplifies the radio signals of the channels CH1 to CH6 received via the antenna 11 and outputs the amplified signals to the generating unit 20. (Generation part)

[0040] The generation unit 20 generates, from the wireless signal, reception data for the channels CH1 to CH6 used for transmitting ship information.

[0041] More specifically, the mixer 21 converts the radio signal received from the amplifier 12 into a baseband analog signal using an LO (Local Oscillator) signal received from a local oscillator (not shown), and outputs the converted analog signal to the AD conversion unit 22.

[0042] AD conversion unit 22 converts the analog signal received from mixer 21 into a digital signal and outputs the digital signal to filter unit 23.

[0043] Filter unit 23 is, for example, a BPF (Band Pass Filter), and attenuates, of the frequency components of the signal indicated by the digital signal received from AD conversion unit 22, components outside a predetermined frequency band.

[0044] For example, filter units 23_1, 23_3, 23_5, 23_7, 23_9, and 23_11 attenuate, from among frequency components of the signal indicated by the digital signal received from AD conversion unit 22, components outside the frequency bands corresponding to channels CH1 to CH6, respectively.

[0045] More specifically, filter unit 23_1 attenuates, among the frequency components of the signal indicated by the digital signal received from AD conversion unit 22, components outside a frequency band F1 corresponding to channel CH1. Filter unit 23_3 attenuates, among the frequency components of the signal indicated by the digital signal received from AD conversion unit 22, components outside a frequency band F2 corresponding to channel CH2. Filter unit 23_5 attenuates, among the frequency components of the signal indicated by the digital signal received from AD conversion unit 22, components outside a frequency band F3 corresponding to channel CH3. Filter unit 23_7 attenuates, among the frequency components of the signal indicated by the digital signal received from AD conversion unit 22, components outside a frequency band F4 corresponding to channel CH4. Filter unit 23_9 attenuates, among the frequency components of the signal indicated by the digital signal received from AD conversion unit 22, components outside a frequency band F5 corresponding to channel CH5. Furthermore, filter unit 23_11 attenuates, among the frequency components of the signal indicated by the digital signal received from AD conversion unit 22, components outside frequency band F6 corresponding to channel CH6.

[0046] Furthermore, for example, filter units 23_2, 23_4, 23_6, 23_8, and 23_10 attenuate components outside the frequency band including the boundary frequency of the corresponding adjacent channel, among the frequency components of the signal indicated by the digital signal received from AD conversion unit 22.

[0047] More specifically, filter unit 23_2 attenuates, among the frequency components of the signal represented by the digital signal received from AD conversion unit 22, components outside a frequency band F1s between a center frequency C1 of frequency band F1 and a center frequency C2 of frequency band F2. Filter unit 23_4 attenuates, among the frequency components of the signal represented by the digital signal received from AD conversion unit 22, components outside a frequency band F2s between a center frequency C2 and a center frequency C3 of frequency band F3. Filter unit 23_6 attenuates, among the frequency components of the signal represented by the digital signal received from AD conversion unit 22, components outside a frequency band F3s between a center frequency C3 and a center frequency C4 of frequency band F4. Filter unit 23_8 attenuates, among the frequency components of the signal represented by the digital signal received from AD conversion unit 22, components outside a frequency band F4s between a center frequency C4 and a center frequency C5 of frequency band F5. Furthermore, filter unit 23_10 attenuates, of the frequency components of the signal indicated by the digital signal received from AD conversion unit 22, components outside a frequency band F5s between center frequency C5 and the center frequency C6 of frequency band F6.

[0048] The transfer unit 24 stores the digital signal that has passed through the filter unit 23 in a memory area 41 in the storage unit 40 .

[0049] More specifically, the transfer unit 24_1 stores the received data D1 of the channel CH1, which is a digital signal that has passed through the filter unit 23_1, in the memory area 41_1. The transfer unit 24_3 stores the received data D2 of the channel CH2, which is a digital signal that has passed through the filter unit 23_3, in the memory area 41_3. The transfer unit 24_5 stores the received data D3 of the channel CH3, which is a digital signal that has passed through the filter unit 23_5, in the memory area 41_5. The transfer unit 24_7 stores the received data D4 of the channel CH4, which is a digital signal that has passed through the filter unit 23_7, in the memory area 41_7. The transfer unit 24_9 stores the received data D5 of the channel CH5, which is a digital signal that has passed through the filter unit 23_9, in the memory area 41_9. The transfer unit 24_11 stores the received data D6 of the channel CH6, which is a digital signal that has passed through the filter unit 23_11, in the memory area 41_11.

[0050] Furthermore, transfer unit 24_2 stores received data D1s of frequency band F1s, which is a digital signal that has passed through filter unit 23_2, in memory area 41_2. Transfer unit 24_4 stores received data D2s of frequency band F2s, which is a digital signal that has passed through filter unit 23_4, in memory area 41_4. Transfer unit 24_6 stores received data D3s of frequency band F3s, which is a digital signal that has passed through filter unit 23_6, in memory area 41_6. Transfer unit 24_8 stores received data D4s of frequency band F4s, which is a digital signal that has passed through filter unit 23_8, in memory area 41_8. Transfer unit 24_10 stores received data D5s of frequency band F5s, which is a digital signal that has passed through filter unit 23_10, in memory area 41_10.

[0051] (Detection unit) The detector 30 performs a detection process to detect the reception levels of the channels CH1 to CH6. For example, in the detection process, the detector 30 further detects the reception levels at the boundary frequencies of adjacent channels.

[0052] For example, at a detection timing according to a predetermined detection cycle, the detection unit 30 generates a frequency spectrum of the digital signal by performing FFT (Fast Fourier Transform) processing on the digital signal that has passed through the filter unit 23 for a predetermined length of time. The detection unit 30 compares the signal strength of a predetermined frequency indicated by the generated frequency spectrum with a predetermined threshold TH1.

[0053] More specifically, the detection unit 30 performs FFT processing on the digital signal that has passed through the filter unit 23_1 to generate a frequency spectrum SP1 of the digital signal. The detection unit 30 compares the signal strength at the center frequency C1 indicated by the frequency spectrum SP1 with a threshold TH1.

[0054] The detection unit 30 also performs FFT processing on the digital signal that has passed through the filter unit 23_2 to generate a frequency spectrum SP1s of the digital signal. The detection unit 30 compares the signal strength at a boundary frequency C1s, which is the boundary frequency between channel CH1 and channel CH2 and is indicated by the frequency spectrum SP1s, with a threshold value TH1.

[0055] Furthermore, the detection unit 30 performs FFT processing on the digital signal that has passed through the filter unit 23_3 to generate a frequency spectrum SP2 of the digital signal. The detection unit 30 compares the signal strength at the center frequency C2 indicated by the frequency spectrum SP2 with a threshold TH1.

[0056] The detection unit 30 also performs FFT processing on the digital signal that has passed through the filter unit 23_4 to generate a frequency spectrum SP2s of the digital signal. The detection unit 30 compares the signal strength at a boundary frequency C2s, which is the boundary frequency between channel CH2 and channel CH3 and is indicated by the frequency spectrum SP2s, with a threshold TH1.

[0057] Furthermore, the detection unit 30 performs FFT processing on the digital signal that has passed through the filter unit 23_5 to generate a frequency spectrum SP3 of the digital signal. The detection unit 30 compares the signal strength at the center frequency C3 indicated by the frequency spectrum SP3 with a threshold TH1.

[0058] The detection unit 30 also performs FFT processing on the digital signal that has passed through the filter unit 23_6 to generate a frequency spectrum SP3s of the digital signal. The detection unit 30 compares the signal strength at a boundary frequency C3s, which is the boundary frequency between channel CH3 and channel CH4 and is indicated by the frequency spectrum SP3s, with a threshold TH1.

[0059] The detection unit 30 also performs FFT processing on the digital signal that has passed through the filter unit 23_7 to generate a frequency spectrum SP4 of the digital signal. The detection unit 30 compares the signal strength at the center frequency C4 indicated by the frequency spectrum SP4 with a threshold TH1.

[0060] Furthermore, the detection unit 30 performs FFT processing on the digital signal that has passed through the filter unit 23_8 to generate a frequency spectrum SP4s of the digital signal. The detection unit 30 compares the signal strength at a boundary frequency C4s, which is the boundary frequency between channel CH4 and channel CH5 and is indicated by the frequency spectrum SP4s, with a threshold value TH1.

[0061] Furthermore, the detection unit 30 performs FFT processing on the digital signal that has passed through the filter unit 23_9 to generate a frequency spectrum SP5 of the digital signal. The detection unit 30 compares the signal strength at the center frequency C5 indicated by the frequency spectrum SP5 with a threshold TH1.

[0062] Furthermore, the detection unit 30 performs FFT processing on the digital signal that has passed through the filter unit 23_10 to generate a frequency spectrum SP5s of the digital signal. The detection unit 30 compares the signal strength at a boundary frequency C5s, which is the boundary frequency between channels CH5 and CH6 and is indicated by the frequency spectrum SP5s, with a threshold TH1.

[0063] Furthermore, the detection unit 30 performs FFT processing on the digital signal that has passed through the filter unit 23_11 to generate a frequency spectrum SP6 of the digital signal. The detection unit 30 compares the signal strength at the center frequency C6 indicated by the frequency spectrum SP6 with a threshold TH1.

[0064] Hereinafter, each of the center frequencies C1 to C6 will also be referred to as a center frequency C, and each of the boundary frequencies C1s to C5s will also be referred to as a boundary frequency Cs.

[0065] 3 is a diagram showing an example of a frequency spectrum generated by a detection unit in a ship information exchange device according to an embodiment of the present invention. FIG. 3 shows a frequency spectrum SP1 of a passing signal of a filter unit 23_1 generated by a detection unit 30 in a ship information exchange device 101 that receives a radio signal on channel CH1 containing ship information.

[0066] 3, in the ship information exchange device 101 that receives a radio signal on channel CH1 containing ship information, the signal strength at the center frequency C1 is equal to or greater than the threshold value TH1 in the frequency spectrum SP1 generated by the detection unit 30. On the other hand, in the frequency spectrum SP1, the signal strength at the boundary frequency C1s is less than the threshold value TH1.

[0067] 4 is a diagram showing another example of a frequency spectrum generated by a detection unit in a ship information exchange device according to an embodiment of the present invention. Compared to FIG. 3, FIG. 4 further shows a frequency spectrum SP2 of a passing signal of a filter unit 23_3 generated by a detection unit 30 in a ship information exchange device 101 that also receives a radio signal of channel CH2 containing ship information in parallel.

[0068] 4, in the ship information exchange device 101 that also receives in parallel a radio signal on channel CH2 containing ship information, the signal strength at the center frequency C2 in the frequency spectrum SP2 generated by the detection unit 30 is equal to or greater than the threshold value TH1. On the other hand, in the frequency spectrum SP2, the signal strength at the boundary frequency C1s is less than the threshold value TH1.

[0069] Fig. 5 is a diagram showing another example of a frequency spectrum generated by a detection unit in a ship information exchange device according to an embodiment of the present invention. Fig. 5 shows a frequency spectrum SP1s of a passing signal of a filter unit 23_2 generated by a detection unit 30 in a ship information exchange device 101 that receives a radio signal on a composite channel CH12 of channels CH1 and CH2 containing ship information.

[0070] Referring to FIG. 5, in the ship information exchange device 101 that receives the radio signal of the composite channel CH12 containing the ship information, in the frequency spectrum SP1s generated by the detection unit 30, the signal strength at the boundary frequency C1s is equal to or greater than the threshold value TH1.

[0071] The detection unit 30 notifies the processing unit 50 of the comparison result between the signal strengths of the center frequency C and the boundary frequency Cs and the threshold value TH1. As an example, the detection unit 30 notifies the processing unit 50 of the comparison result via the signal line SL by setting the level of a notification signal, which is a signal to be output to the signal line SL, in accordance with the comparison result between the signal strengths of the center frequency C and the boundary frequency Cs and the threshold value TH1.

[0072] More specifically, when the signal strength of the center frequency C is equal to or greater than the threshold value TH1, the detection unit 30 sets the notification signal to be output to the corresponding signal line SL to a high level, and when the signal strength of the center frequency C is less than the threshold value TH1, the detection unit 30 sets the notification signal to be output to the corresponding signal line SL to a low level.

[0073] In addition, when the signal strength of the boundary frequency Cs is greater than or equal to the threshold value TH1, the detection unit 30 sets the notification signal to be output to the corresponding signal line SL to a high level, and when the signal strength of the boundary frequency Cs is less than the threshold value TH1, the detection unit 30 sets the notification signal to be output to the corresponding signal line SL to a low level.

[0074] Fig. 6 is a diagram showing an example of a comparison result notified to a processing unit by a detection unit in a ship information exchange device according to an embodiment of the present invention. Fig. 6 shows a notification signal output to a signal line SL by a detection unit 30 in a ship information exchange device 101 that has received a radio signal RS1 on channel CH1 containing ship information. In Fig. 6, a high-level notification signal is shown as "1" and a low-level notification signal is shown as "0". The same applies to Figs. 7 and onwards.

[0075] Referring to Figure 6, in the ship information exchange device 101 that receives the radio signal RS1, in the frequency spectrum SP1 generated by the detection unit 30, the signal strength at the center frequency C1 is greater than or equal to the threshold value TH1, while in the frequency spectra SP2 to SP6 and frequency spectra SP1s to SP5s, the signal strength at the center frequencies C2 to C6 and boundary frequencies C1s to C5s is less than the threshold value TH1.

[0076] In this case, for example, the detection unit 30 sets the notification signal output to the signal line SL1 to a high level, and sets the notification signals output to the signal lines SL2 to SL11 to a low level.

[0077] 7 is a diagram showing another example of a comparison result notified to a processing unit by a detection unit in a ship information exchange device according to an embodiment of the present invention. Fig. 7 shows a notification signal output to a signal line SL by a detection unit 30 in a ship information exchange device 101 that has received a radio signal RS1 on channel CH1 containing ship information and a radio signal RS2 on channel CH2 containing ship information.

[0078] Referring to Figure 7, in the ship information exchange device 101 that receives the radio signals RS1 and RS2, in the frequency spectra SP1 and SP2 generated by the detection unit 30, the signal strength at the center frequencies C1 and C2 is greater than or equal to the threshold value TH1, while in the frequency spectra SP3 to SP6 and frequency spectra SP1s to SP5s, the signal strength at the center frequencies C3 to C6 and boundary frequencies C1s to C5s is less than the threshold value TH1.

[0079] In this case, for example, the detection unit 30 sets the notification signals output to the signal lines SL1 and SL2 to a high level, and sets the notification signals output to the signal lines SL2 and SL4 to SL11 to a low level.

[0080] 8 is a diagram showing another example of a comparison result notified to a processing unit by a detection unit in a ship information exchange device according to an embodiment of the present invention. Fig. 8 shows a notification signal output to a signal line SL by a detection unit 30 in a ship information exchange device 101 that has received a radio signal RS12 on a composite channel CH12 of channels CH1 and CH2 containing ship information.

[0081] Referring to Figure 8, in the ship information exchange device 101 that receives the radio signal RS12, in the frequency spectra SP1, SP2, and SP1s generated by the detection unit 30, the signal strength at the center frequencies C1, C2 and boundary frequency C1s is greater than or equal to the threshold value TH1, while in the frequency spectra SP3 to SP6 and frequency spectra SP2s to SP5s, the signal strength at the center frequencies C3 to C6 and boundary frequencies C2s to C5s is less than the threshold value TH1.

[0082] In this case, for example, the detection unit 30 sets the notification signals output to the signal lines SL1 to SL3 to a high level, and sets the notification signals output to the signal lines SL4 to SL11 to a low level.

[0083] Fig. 9 is a diagram showing another example of the comparison result notified to the processing unit by the detection unit in the ship information exchange device according to the embodiment of the present invention. Fig. 9 shows the notification signals output to the signal lines SL1 to SL11 by the detection unit 30 in the ship information exchange device 101 that has received the radio signal RS1234 of the composite channel CH1234 of channels CH1 to CH4 containing ship information, the radio signal RS5 of channel CH5 containing ship information, and the radio signal RS5 of channel CH6 containing ship information.

[0084] Referring to Figure 9, in the ship information exchange device 101 that receives the radio signals RS1234, RS5, and RS6, in the frequency spectra SP1 to SP6, SP1s to SP3s generated by the detection unit 30, the signal strength at the center frequencies C1 to C6 and the boundary frequencies C1s to C3s is greater than or equal to the threshold value TH1, while in the frequency spectra SP4s and SP5s, the signal strength at the boundary frequencies C4s and C5s is less than the threshold value TH1.

[0085] In this case, for example, the detection unit 30 sets the notification signals output to the signal lines SL1 to SL7, SL9, and SL11 to a high level, and sets the notification signals output to the signal lines SL8 and SL10 to a low level.

[0086] Fig. 10 is a diagram showing another example of the comparison result notified to the processing unit by the detection unit in the ship information exchange device according to the embodiment of the present invention. Fig. 10 shows the notification signals output to the signal lines SL1 to SL11 by the detection unit 30 in the ship information exchange device 101 that has received the radio signal RS1234 of the composite channel CH1234 of the channels CH1 to CH4 that includes ship information, and the radio signal RS56 of the composite channel CH56 of the channels CH5 and CH6 that includes ship information.

[0087] Referring to Figure 10, in the ship information exchange device 101 that receives the radio signals RS1234 and RS56, in the frequency spectra SP1 to SP6, SP1s to SP3s, and SP5s generated by the detection unit 30, the signal strength at the center frequencies C1 to C6 and the boundary frequencies C1s to C3s, and C5s is greater than or equal to the threshold value TH1, while in the frequency spectrum SP4s, the signal strength at the boundary frequency C4s is less than the threshold value TH1.

[0088] In this case, for example, the detection unit 30 sets the notification signals output to the signal lines SL1 to SL7 and SL9 to SL11 to a high level, and sets the notification signal output to the signal line SL8 to a low level.

[0089] In addition, the detection unit 30 may be configured to compare the signal strength at the center frequency C with a threshold value TH1, and also compare the signal strength at the boundary frequency Cs with a threshold value TH2 different from the threshold value TH1, and notify the processing unit 50 of the comparison results.

[0090] In addition, the detection unit 30 may be configured to use a value other than the threshold value TH1 as the threshold value used for comparison with the signal strength at at least one center frequency C, or may be configured to use a value other than the threshold value TH1 as the threshold value used for comparison with the signal strength at at least one boundary frequency Cs.

[0091] (Processing section) The processing unit 50 determines the received data to be demodulated in accordance with the detection result of the reception level by the detection unit 30, and demodulates the determined received data to be demodulated. More specifically, the processing unit 50 determines the received data to be demodulated in accordance with the comparison result notified from the detection unit 30, i.e., the level of the notification signal received from the detection unit 30 via the signal line SL, and obtains the determined received data to be demodulated from the storage unit 40 and demodulates it.

[0092] For example, the processing unit 50 determines the number of channels used to transmit the ship information based on the detection result of the reception level by the detection unit 30, and determines the reception data to be demodulated based on the determination result.

[0093] For example, when the reception level at the center frequency C1 of channel CH1 is equal to or greater than a predetermined value and the reception level at the boundary frequency C1s is less than a predetermined value, the processing unit 50 demodulates the reception data D1 of channel CH1.

[0094] More specifically, in a state where the processing unit 50 receives the notification signal shown in Fig. 6 from the detection unit 30, the processing unit 50 determines that the channel used for transmitting the ship information is channel CH1. In this case, every time the transfer unit 24_1 stores the received data D1 in the memory area 41_1, the processing unit 50 retrieves the received data D1 from the memory area 41_1 and demodulates the data. On the other hand, in a state where the processing unit 50 receives the notification signal shown in Fig. 6 from the detection unit 30, the processing unit 50 erases the received data stored in the memory areas 41_2 to 41_11 by the transfer units 24_2 to 24_11 without demodulating it.

[0095] Also, for example, when the reception level at the center frequency C1 of channel CH1 and the reception level at the center frequency C2 of channel CH2, which are channels of a continuous frequency band, are equal to or greater than a predetermined value, and the reception level at the boundary frequency C1s is less than a predetermined value, the processing unit 50 demodulates the reception data D1 of channel CH1 and the reception data D2 of channel CH2, respectively.

[0096] More specifically, in a state where the processing unit 50 receives the notification signal shown in Fig. 7 from the detection unit 30, the processing unit 50 determines that the channels used for transmitting the ship information are channels CH1 and CH2. In this case, every time the transfer unit 24_1 stores the received data D1 in the memory area 41_1, the processing unit 50 retrieves the received data D1 from the memory area 41_1 and demodulates it, and every time the transfer unit 24_3 stores the received data D2 in the memory area 41_3, the processing unit 50 retrieves the received data D2 from the memory area 41_3 and demodulates it. On the other hand, in a state where the processing unit 50 receives the notification signal shown in Fig. 7 from the detection unit 30, the processing unit 50 erases the received data stored in the memory areas 41_2, 41_4 to 41_11 by the transfer units 24_2, 24_4 to 24_11 without demodulating it.

[0097] Furthermore, for example, when the reception level at the center frequency of each of the channels of the plurality of consecutive frequency bands is equal to or greater than a predetermined value, and the reception level at the boundary frequency between adjacent channels of the plurality of consecutive frequency bands is equal to or greater than a predetermined value, the processing unit 50 demodulates composite data obtained by combining the reception data of each of the channels of the plurality of consecutive frequency bands.

[0098] As an example, when the reception level at the center frequency C1 of channel CH1, which is a channel of a continuous frequency band, and the reception level at the center frequency C2 of channel CH2 are equal to or greater than a predetermined value, and the reception level at the boundary frequency C1s is equal to or greater than a predetermined value, the processing unit 50 demodulates the composite data obtained by combining the reception data D1 and D2 of channel CH1 and channel CH2.

[0099] More specifically, when the processing unit 50 receives the notification signal shown in Fig. 8 from the detection unit 30, it determines that the channel used to transmit the ship information is the composite channel CH12 of the channels CH1 and CH2. In this case, every time the transfer units 24_1 and 24_3 store the received data D1 and D2 in the memory areas 41_1 and 41_3, the processing unit 50 retrieves the received data D1 and D2 from the memory areas 41_1 and 41_3 and combines them to generate composite data D12, and demodulates the generated composite data D12. On the other hand, when the processing unit 50 receives the notification signal shown in Fig. 8 from the detection unit 30, it deletes the received data stored in the memory areas 41_4 to 41_11 by the transfer units 24_4 to 24_11 without demodulating them. Note that the processing unit 50 may be configured to retrieve the received data D1, D1s, and D2 from the memory areas 41_1 to 41_3 and combine them to generate the composite data D12.

[0100] [Operation flow] Each device in the ship information exchange system according to an embodiment of the present disclosure includes a computer including a memory, and a processing unit such as a CPU in the computer reads and executes a program including some or all of the steps in the following flowchart from the memory. The programs for these devices can be installed externally. The programs for these devices are distributed in a state stored on a recording medium or via a communication line.

[0101] FIG. 11 is a flowchart illustrating an example of an operation performed by the ship information exchange device according to the embodiment of the present disclosure when demodulating received data.

[0102] Referring to FIG. 11, first, the vessel information exchange device 101 starts receiving a radio signal (step S11).

[0103] Next, the ship information exchange device 101 starts generating the received data D1 to D6 of the channels CH1 to CH6 and the received data D1s to D5s of the frequency bands F1s to F5s and storing them in the storage unit 40 (step S12).

[0104] Next, the ship information exchange device 101 waits for the detection timing according to a predetermined detection period (NO in step S13), and when the detection timing arrives (YES in step S13), it generates frequency spectra SP1 to SP6, SP1s to SP5s by performing FFT processing on the digital signal that has passed through the filter unit 23 (step S14).

[0105] Next, the ship information exchange device 101 detects the reception levels of channels CH1 to CH6 and the reception levels at boundary frequencies C1s to C5s using the generated frequency spectra SP1 to SP6 and SP1s to SP5s. More specifically, the ship information exchange device 101 compares the signal strength at center frequency C and the signal strength at boundary frequency Cs with threshold value TH1 (step S15).

[0106] Next, the ship information exchange device 101 determines the number of channels used to transmit the ship information based on the comparison result, and determines the received data to be demodulated based on the determination result (step S16).

[0107] Next, the ship information exchange device 101 starts demodulating the received data determined to be the target for demodulation. More specifically, every time the ship information exchange device 101 generates the received data D1 to D6, D1s to D5s, it retrieves the received data to be demodulated from the storage unit 40 among the generated received data D1 to D6, D1s to D5s and demodulates it, and deletes the received data not to be demodulated from the storage unit 40 (step S17).

[0108] Next, the ship information exchange device 101 waits for a new detection timing (NO in step S13).

[0109] In the ship information exchange device 101 according to the embodiment of the present invention, the detection unit 30 is configured to compare the signal strength of the center frequencies C1 to C6 and boundary frequencies C1s to C5s indicated by the frequency spectra SP1 to SP6, SP1s to SP5s of the digital signal that has passed through the filter unit 23 with a threshold value TH1 and notify the processing unit 50 of the comparison result, but this is not limiting. The detection unit 30 may also be configured to perform detection processing in an analog stage. More specifically, a plurality of pairs of analog BPFs and AD conversion units may be provided downstream of the mixer 21, and the detection unit 30 may be configured to compare the signal strength of the center frequency C and boundary frequency Cs of the analog signal that has passed through each analog BPF with a threshold value TH1 and notify the processing unit 50 of the comparison result.

[0110] In addition, in the ship information exchange device 101 according to the embodiment of the present invention, the generation unit 20 is configured to include the transfer units 24_2, 24_4, 24_6, 24_8, and 24_10, but is not limited to this. The generation unit 20 may be configured to include the transfer units 24_1, 24_3, 24_5, 24_7, 24_9, and 24_11, but not to include the transfer units 24_2, 24_4, 24_6, 24_8, and 24_10. In this case, the generation unit 20 generates the composite data without using the received data D1s to D5s.

[0111] Meanwhile, a technique capable of reducing the processing load of the demodulation process is desired.

[0112] In contrast, in the ship information exchange device 101 according to the embodiment of the present invention, the receiving unit 10 receives a radio signal. The generating unit 20 generates received data of channels CH1 to CH6 used for transmitting ship information from the radio signal. The detecting unit 30 detects the reception levels of channels CH1 to CH6. The processing unit 50 demodulates the received data. The processing unit 50 determines the received data to be demodulated according to the detection result of the reception level.

[0113] In this way, the configuration that determines the received data to be demodulated according to the reception levels of channels CH1 to CH6 allows selective demodulation of received data that includes ship information, compared to a configuration that sequentially and repeatedly performs demodulation processing of six pieces of received data contained in the radio signals of channels CH1 to CH6 in a time-division manner regardless of whether the radio signals contain ship information, thereby suppressing an increase in the processing load caused by demodulating received data that does not contain ship information and speeding up the response of various processes in the processing unit 50. Therefore, the processing load of the demodulation processing can be reduced, and the processing cost and production cost for performing the demodulation can be reduced.

[0114] Furthermore, the processing unit 50 determines the number of channels used for transmitting the ship information based on the detection result, and determines the received data to be demodulated based on the determination result.

[0115] With this configuration, in a system in which radio signals are transmitted and received using a composite channel formed by combining a plurality of channels, it is possible to appropriately demodulate received data on the composite channel.

[0116] The detector 30 also detects the reception level at the boundary frequency between adjacent channels.

[0117] Such an arrangement allows for a more accurate determination of the number of channels used to transmit the vessel information.

[0118] Furthermore, the processing unit 50 demodulates the received data of channel CH1 when the reception level of channel CH1 is equal to or greater than a predetermined value and the reception level at the boundary frequency between channel CH1 and channel CH2 adjacent to channel CH1 is less than a predetermined value.

[0119] With this configuration, the received data of channel CH1 can be demodulated separately from the received data of the composite channel CH12 of channels CH1 and CH2.

[0120] In addition, when the reception levels of channels CH1 and CH2 in the continuous frequency band are equal to or greater than a predetermined value and the reception level at the boundary frequency between channels CH1 and CH2 is less than a predetermined value, the processing unit 50 demodulates the reception data of channel CH1 and the reception data of channel CH2, respectively.

[0121] With this configuration, the received data of channel CH1 and the received data of channel CH2 can be demodulated separately from the received data of the composite channel CH12 of channels CH1 and CH2.

[0122] In addition, when the reception levels of channels CH1 and CH2 in the continuous frequency band are equal to or higher than a predetermined value and the reception level at the boundary frequency between channels CH1 and CH2 is equal to or higher than a predetermined value, the processing unit 50 demodulates the composite data obtained by combining the reception data of channels CH1 and CH2.

[0123] With this configuration, the received data of the combined channel CH12 of channels CH1 and CH2 can be demodulated separately from the received data of channel CH1 and the received data of channel CH2.

[0124] Furthermore, when the reception level of each of the channels of a plurality of consecutive frequency bands is equal to or greater than a predetermined value and the reception level at each boundary frequency between adjacent channels is equal to or greater than a predetermined value, the processing unit 50 demodulates composite data obtained by combining the reception data of each of the channels of a plurality of consecutive frequency bands.

[0125] With this configuration, the received data of the composite channel can be demodulated separately from the received data of the single channel.

[0126] The processing unit 50 also determines the received data to be demodulated based on the result of comparing the reception level of the channel with the threshold TH1 and the result of comparing the reception level at the boundary frequency with a threshold TH2 different from the threshold TH1.

[0127] This configuration makes it possible to more accurately determine the number of channels used to transmit ship information compared to a configuration in which the reception level is detected using a common threshold.

[0128] The vessel information also includes at least one of the vessel's identification code, vessel name, vessel position, vessel course, vessel speed, and vessel destination.

[0129] Such a configuration allows useful information about the vessel 1 to be exchanged.

[0130] Furthermore, a ship information exchange method according to an embodiment of the present invention is a ship information exchange method in a ship information exchange device 101. In this ship information exchange method, first, a radio signal is received. Next, received data of channels CH1 to CH6 used for transmitting ship information is generated from the radio signal. Next, the reception levels of channels CH1 to CH6 are detected. Next, the received data to be demodulated is determined according to the detection results of the reception levels. Next, the received data to be demodulated is demodulated.

[0131] In this way, by determining the received data to be demodulated according to the reception levels of channels CH1 to CH6, it is possible to selectively demodulate received data containing ship information, compared to a configuration in which the demodulation process of the six received data contained in the radio signals of channels CH1 to CH6 is performed sequentially and repeatedly in a time-division manner, regardless of whether the radio signals contain ship information. This makes it possible to suppress an increase in the processing load caused by demodulating received data that does not contain ship information and to speed up the response of various processes. Therefore, it is possible to reduce the processing load of the demodulation process and reduce the processing cost and production cost for performing the demodulation.

[0132] The above-described embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0133] 1 ship 10 Receiving unit 11 Antenna 12 Amplifiers 20 Generation part 21 Mixer 22 AD conversion section 23 Filter section 24 Transfer Unit 30 Detection unit 40 Storage section 41 Memory Area 50 Processing section 101 Ship information exchange device 201 Ship Information Exchange System SL signal line

Claims

1. a receiving unit for receiving a wireless signal; a generation unit that generates, from the wireless signal, reception data of a plurality of channels used for transmitting ship information; a detection unit that detects the reception level of each of the channels; a demodulation unit that demodulates the received data, the demodulation unit determines the received data to be demodulated in accordance with the detection result of the reception level; The demodulation unit determines the number of channels used to transmit the ship information based on the detection result, and determines the received data to be demodulated based on the determination result. The vessel information exchange device, wherein the detection unit further detects a reception level at a boundary frequency between adjacent channels.

2. 2. The ship information exchange device according to claim 1, wherein the demodulation unit demodulates the received data of the first channel when the reception level of the first channel is equal to or greater than a predetermined value and the reception level at a boundary frequency between the first channel and the channel adjacent to the first channel is less than a predetermined value.

3. The ship information exchange device according to claim 1 or claim 2, wherein the demodulation unit demodulates the received data of the first channel and the received data of the second channel when the reception levels of the first channel and the second channel, which are channels of a continuous frequency band, are equal to or greater than a predetermined value and the reception level at the boundary frequency between the first channel and the second channel is less than a predetermined value.

4. A ship information exchange device as described in any one of claims 1 to 3, wherein the demodulation unit demodulates composite data obtained by combining the received data of the first channel and the second channel when the receiving levels of the first channel and the second channel, which are channels of a continuous frequency band, are equal to or higher than a predetermined value and the receiving level at the boundary frequency between the first channel and the second channel is equal to or higher than a predetermined value.

5. 5. A ship information exchange device as described in any one of claims 1 to 4, wherein the demodulation unit demodulates composite data obtained by combining the received data of each of the channels of the plurality of consecutive frequency bands when the receiving level of each of the channels of the plurality of consecutive frequency bands is equal to or greater than a predetermined value and the receiving level at each boundary frequency of the adjacent channels is equal to or greater than a predetermined value.

6. A ship information exchange device described in any one of claims 1 to 5, wherein the demodulation unit determines the received data to be demodulated based on a comparison result between the reception level of the channel and a first threshold, and a comparison result between the reception level at the boundary frequency and a second threshold different from the first threshold.

7. The vessel information exchange device according to any one of claims 1 to 6, wherein the vessel information includes at least one of the vessel identification code, vessel name, vessel position, vessel course, vessel speed, and vessel destination.

8. A ship information exchange method in a ship information exchange device, Receives radio signals, generating reception data of a plurality of channels used for transmitting ship information from the wireless signal; Detecting a reception level of each of the channels, and further detecting a reception level at a boundary frequency of the adjacent channels; determining the number of channels used to transmit the ship information based on the detection result of the reception level, and determining the reception data to be demodulated based on the determination result; A ship information exchange method for demodulating the received data to be demodulated.

9. A computer, receiving a wireless signal; generating, from the wireless signal, reception data of a plurality of channels used for transmitting ship information; A process of detecting the reception level of each of the channels; a process of determining the received data to be demodulated according to the detection result of the reception level; a process of demodulating the received data to be demodulated, In the process of demodulating the received data, the number of the channels used to transmit the ship information is determined based on the detection result, and the received data to be demodulated is determined based on the determination result; A ship information exchange program, wherein the process of detecting the reception level further detects the reception level at a boundary frequency between adjacent channels.

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