JP6320126B2 - Wireless signal discrimination device - Google Patents

Description

  The present invention relates to a radio signal discriminating apparatus that discriminates whether or not a transmission end of a radio signal arriving at an aerial line via a navigation monitoring automatic broadcasting system is present or not.

  AIS (Automatic Identification System) devices are being installed in many ships to improve safety and convenience in navigation, as they are being made cheaper, smaller, with lower power consumption and higher functionality as technology advances. .

  In addition, such an AIS device is suitable for ships that have a gross tonnage of 300 tons or more for ships that sail internationally, ships that have a total tonnage of 500 tons or more for ships that travel only in the territorial waters, and passenger ships that sail internationally. The loading obligation is imposed on all. In addition, many simple AIS devices that can be operated even if there are no radio workers are being installed in ships that do not have the obligation to install them.

FIG. 5 is a diagram illustrating a configuration example of the AIS apparatus.
In the figure, the feeding points of the antennas 31AIS and 31GPS are respectively connected to the first antenna terminal and the second antenna terminal of the transponder 40, and the digital input / output port of the transponder 40 is connected to the cascaded collector / distributor 50 and An operation display unit 60 is connected. A desired external device or sensor (none of which is shown) is connected to the collector / distributor 50.

The transponder 40 includes the following elements.
(1) A switch (SW) 41 which is a single pole double throw and whose common contact is connected to the first antenna terminal.
(2) Hybrid (H) 42 having a first terminal connected to the make (break) contact of switch 41

(3) TDMA receivers 43-1 and 43-2 and DSC receiver 44 connected to the second to fourth terminals of the hybrid 42, respectively.
(4) Modulator / demodulator 45 having first to third demodulation inputs connected to the outputs of these TDMA receivers 43-1, 43-2 and DSC receiver 44, respectively.

(5) A transmitter 46 having a modulation input connected to the modulation output of the modem 45 and having an output connected to a break (make) contact of the switch 41
(6) GPS receiver 47 having an input connected to the second antenna terminal

(7) A control unit 48 having a digital input / output port connected to the above described collector / distributor 50 in addition to an input / output port connected to the input / output port of the modem 45 and the output of the GPS receiver 47, respectively.

  In the AIS apparatus having such a configuration, the switch 41 and the TDMA receiving units 43-1 and 43-2 operate under the control of the control unit 48, and provide the modulation / demodulation unit 45 with a received wave that has arrived at the antenna 31AIS from another ship.

  The modem 45 demodulates the received wave to obtain identification information, heading, ship position, course, speed, etc. (hereinafter referred to as “notification information”) of the other ship. The control unit 48 converts the notification information obtained in this way into information of a predetermined format and content, and delivers it to the operation display unit 60 via the collector / distributor 50. The operation display unit 60 displays information delivered from the control unit 48 via the collector / distributor 50, thereby notifying personnel involved in the navigation of the ship.

  On the other hand, the collector / distributor 50 is linked to the above-described external devices and sensors under the control of the control unit 48, thereby identifying the ship's identification information, heading, ship position, course, speed, etc. (hereinafter referred to as "notification information"). ) Are collected and given to the control unit 48.

  The GPS receiving unit 47 applies a predetermined satellite navigation to a radio signal arriving at the antenna 31 GPS from a GPS satellite (not shown), so that the time (based on the multiple access performed by the TDMA receiving units 43-1 and 43-2 and the like) And the position of the ship (antenna 31GPS), and the position is handed over to the control unit 48 as information that can be incorporated into the notification information of the ship.

  The control unit 48 converts these pieces of information into a predetermined format and gives the information to the modem unit 45. The modem unit 45 generates a transmission wave modulated with such information in the form of a control unit 48. The transmission unit 46 transmits the transmission wave to other ships and land stations via the switch 41 and the antenna 31AIS under the control of the control unit 48.

  Note that such transmission waves conform to a predetermined time division multiplexing system under the synchronization control performed by the TDMA receiving units 43-1 and 43-2 to receive the above-described received waves under the control unit 48. It is generated as a burst wave during the transmission time slot (reserved under the control of the control unit 48 or assigned to the ship).

  That is, the AIS device automatically notifies the ship's notification information to surrounding ships and land stations, obtains notification information notified in the same manner from other ships, and performs predetermined processing to obtain the ship. It is used to support collision control, cargo information, navigation management operations, maritime security operations, operation control at ports, etc.

  As prior arts related to the present invention, there are Patent Documents 1 to 5 listed below.

(1) “Ship position information extracting means that receives a ship identification signal transmitted from a ship and extracts at least position information of the ship from the ship identification signal; and captures the position of a target from radar detection data; Target capturing / tracking means for tracking, a first mark indicating the position or speed vector of the ship obtained by the ship position information extracting means, and the position or speed vector of the target obtained by the target capturing / tracking means Control means for displaying the first mark in preference to the second mark at the display position of the first mark or in the vicinity thereof. "The table when displaying the mark of another ship by the automatic vessel identification device (AIS) and the mark of the target by the automatic collision prevention assistance device (ARPA) on the same display screen. The ship display device is characterized in that it eliminates the complexity of the displayed contents and makes it possible to effectively use the capabilities of ARPA.

(2) “Detecting means for detecting other ship information including at least position information of other ships, and the importance of the other ship information detected by the detecting means is determined according to a predetermined condition, and the importance of a preset range is determined. By providing other ship information extracting means for extracting other ship information and a display control means for graphically displaying the position of the other ship corresponding to the extracted other ship information, When displaying the relative position relationship between other ships and own ship or between other ships in graphic form, it prevents the display from becoming complicated when the number of other ships increases and improves visibility. '' Other ship display device with ... Patent Document 2

(3) “The AIS device of the ship with the ARPA radar device is connected to the ARPA radar device via the interface, and the dynamic information of the nearby vessel to be received and the radar symbol information acquired from the ARPA radar device are compared every moment. , Radar symbol information without dynamic information for which a predetermined match is recognized is set as transmission stop warning information, dynamic information without radar symbol information with a predetermined match is set as intangible notification warning information, and the warning information is displayed. By displaying on the device and prompting the operator to be vigilant, and converting the alert information into a report and transmitting it to a nearby vessel, the “transmission AIS device does not stop transmission or the dynamic information without the entity, transmission information By receiving AIS devices and prompting vigilance, the environment where the deterrence effect against unauthorized information transmission is realized is realized. Reliability method AIS transceiver information characterized by the reliability improved "point location ... Patent Document 3

(4) “A ship's navigation support system that is installed in a ship and supports navigation, an AIS (automatic ship identification) device that receives target ship information transmitted from the target ship, and a target ship captured from the radar signal of the radar. ARPA (Automatic Collision Prevention Assistance) device for tracking the ship, own ship position information specifying means for specifying the ship position, and relative to the ship of the target ship from the received target ship position information and the specified ship position information Target relative position calculating means for calculating the position, and the same target determining means for specifying the same target ship that is being tracked by the ARPA device from the relative position of the target ship calculated by the target relative position calculating means And AIS information monitoring means for monitoring the accuracy of the target ship information received by the AIS device and determining whether the target ship information received by the AIS device is incorrect. When the AIS information monitoring means determines that the target ship information is incorrect, it outputs an abnormal signal. By using the characteristics of the AIS device and the ARPA device, the ARPA device complements the AIS device. And improve the reliability of the target ship information received by the AIS device ".

(5) “Target ship information receiving means for receiving target ship position information transmitted from the target ship or a third party in a ship navigation support apparatus that is mounted on a ship and supports navigation, and identifies the ship position. The target ship position information specifying means, the target ship position information calculating means for calculating the relative position of the target ship to the ship from the received target ship position information and the specified ship position information, and the radar signal of the radar The target ship capture and tracking means for providing the movement information of the target ship from the history, the target ship relative position calculated by the target relative position calculation means and the target ship capture and tracking means being tracked The same target determination that identifies the target ship that has obtained the target ship position information by the target ship information receiving means, which is the same as the target ship that is being tracked by the target ship capturing and tracking means, by comparing the relative position of the target ship. Means and equipment The same target determination means is further provided with the same target determination period limiting means for limiting the period during which the same determination is performed. A ship navigation support apparatus characterized by “complementing by utilizing each characteristic of the target ship information received and efficiently integrating information on the target ship”. Patent Document 5

JP 2002-372583 A JP 2003-048595 A JP 2005-141656 A JP 2005-181078 A JP 2005-182539 A

  By the way, in the above-described conventional examples and patent documents, the authenticity of the position indicated by the radio signal arriving from a non-existing ship or the like is not positively discriminated, or even if discriminated, radio that requires a complicated and large processing amount It was realized by using navigation together.

  The present invention provides a radio signal discriminating apparatus capable of accurately discriminating whether or not there is a transmitting end of an incoming radio signal and the possibility of the existence thereof without greatly changing the basic configuration compared to the conventional example. With the goal.

In the first aspect of the present invention, the azimuth calculating means obtains the relative azimuth of the position indicated by the radio signal that has arrived via the navigation monitoring automatic broadcast system. The arrival direction specifying means specifies the arrival direction of the radio signal. The discriminating unit discriminates the authenticity or normality of the radio signal or the position based on the difference between the azimuth and the arrival direction.

  That is, the authenticity and normality of a radio signal that has arrived via a navigation monitoring automatic broadcast system from a transmitting end (device) that does not exist or is located at a position different from the entity can be easily realized without using radio navigation. It is easily distinguished under direction detection.

According to a second aspect of the present invention, in the AIS signal discriminating device according to the first aspect, the arrival direction specifying means may be configured to receive the received waves individually received from different other ships, respectively. The direction of arrival is obtained based on the difference in phase corresponding to the difference in the length of the reaching propagation path and the arrangement of these linear antenna elements .

That is, the linear antenna element receives a radio signal from another ship that is different in authenticity or normality of the radio signal that has arrived through the navigation monitoring automatic broadcast system or the position indicated by the radio signal, and the linear antenna Discrimination is made based on the arrival direction obtained based on the difference in phase corresponding to the difference in the propagation path reaching the element and the arrangement of these linear antenna elements .

In the invention described in claim 3, the radio signal determining apparatus according to claim 1, wherein the arrival direction specifying means, under the beamforming scanning the direction of the main lobe in the range of a predetermined azimuth angle including the azimuth Then, the arrival direction of the radio signal is specified.

  That is, the authenticity and normality of the arrival direction of a radio signal can be determined beyond the range of deviations that can accompany the arrival direction, even for a transponder to which an antenna that can change the direction of the main lobe by beamforming is applied. This is realized without unnecessary beam forming.

  The transponder to which the present invention is applied can improve the performance and reliability at low cost while ensuring the degree of freedom of configuration.

  Further, according to the transponder to which the present invention is applied, it is possible to determine the authenticity or normality of the position indicated by the radio signal that has arrived through the navigation surveillance automatic broadcasting system without significantly changing the configuration of the antenna system. Is efficiently and accurately realized.

  Further, the transponder to which the present invention is applied can be improved in performance and reliability at low cost.

  Therefore, according to the present invention, it is possible to easily reduce or alleviate the vulnerability of the navigation monitoring automatic broadcast system without complicating the configuration and unnecessarily increasing the cost.

It is a figure which shows 1st and 2nd embodiment of this invention. It is an operation | movement flowchart of the control part in 1st embodiment of this invention. It is a figure which shows the structure of a conversion table. It is an operation | movement flowchart of the control part in 2nd embodiment of this invention. It is a figure which shows the structural example of an AIS apparatus.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First embodiment]
FIG. 1 is a diagram showing first and second embodiments of the present invention.
In the figure, components having the same functions and configurations as those shown in FIG. 3 are given the same reference numerals, and descriptions thereof are omitted here.

The configuration of this embodiment is different from the conventional example shown in FIG. 5 in the points listed below.
(1) A control unit 11 is provided instead of the control unit 48.
(2) An antenna 12 composed of linear antenna elements 12E-1 to 12E-6 arranged in parallel to the cylinder axis at predetermined intervals on the side wall of a virtual cylinder is provided instead of the antenna 31AIS.

(3) The power supply control unit 13 having a combined output connected to the power supply points of these linear antenna elements 12E-1 to 12E-6 and connected to the common contact of the switch 41 is provided.
(4) Provided in the power feeding control unit 13 and connected to the six ports corresponding to the feeding points of the linear antenna elements 12-1 to 12-6, respectively, and a specific input port of the control unit 11 A direction finding processor 14 having a connected output port is provided.

FIG. 2 is an operation flowchart of the control unit in the first embodiment of the present invention.
The operation of this embodiment will be described below with reference to FIGS.
The feature of this embodiment is the following processing procedure performed by the control unit 11 in conjunction with the antenna 12, the power feeding control unit 13 and the direction finding processing unit 14 in comparison with the conventional example shown in FIG.

The feed controller 13 feeds the transmission wave given from the transmitter 46 via the switch 41 by making the directivity in the horizontal direction omnidirectional by the linear antenna elements 12-1 to 12-6. Under this power supply, it transmits to other ships and land stations as in the conventional example.
On the other hand, for the received waves R1 to Rn that individually arrive at these linear antenna elements 12-1 to 12-6 from different ships, the power feeding control unit 13 hands over to the direction finding processing unit 14, respectively.

  The direction finding processing unit 14 takes in the received waves R1 to Rn that have been delivered in this manner and individually arrived at the linear antenna elements 12-1 to 12-6, and these received waves Rc (c = 1 to n). ), The difference in phase (φ1c to φ6c) corresponding to the difference in the length of the propagation path reaching the linear antenna elements 12-1 to 12-6, and these lines on the side wall of the virtual cylinder described above Based on the arrangement of the antenna elements 12-1 to 12-6, the arrival angle θc (c = 1 to n) indicating the arrival direction of the received wave is calculated. Note that such an arrival angle θc indicates a geographical orientation of another ship or the like corresponding to the transmission source of the received wave.

  The switch 41 and the TDMA receiving units 43-1 and 43-2 operate under the control unit 48 as in the conventional example, and receive received waves Rc (c = 1 to n) individually arriving at the antenna 12 from other ships. The modulation / demodulation unit 45 is provided.

  Further, the modem 45 demodulates these received waves Rc (c = 1 to n), thereby “notification information c” (c) indicating the identification information, bow, ship position, course, speed, etc. of each other ship. = 1 to n).

Moreover, the control part 11 performs the following process.
(1) The notification information c is converted into an array Ac (c = 1 to n) having a predetermined format and contents (step S1 in FIG. 2).

(2) The relative azimuth angle Θc (c = 1 to n) of the position Lc (c = 1 to n) of the other ship included in the array Ac is obtained (step S2 in FIG. 2).

(3) A deviation δc (c = 1 to n) represented by the following equation is calculated with respect to the azimuth angle Θc and the arrival angle θc (step S3 in FIG. 2).
δc = | θc−Θc |

(4) The magnitude relationship dc (c = 1 to n) between the deviation δc and the predetermined threshold th (≧ 0) is determined (step S4 in FIG. 2).

(5) Deliver the aforementioned “notification information c” and the magnitude relationship dc to the operation display unit 60 via the collector / distributor 50 in association with the received waves Rc (c = 1 to n), respectively (step S5 in FIG. 2). .

  The operation display unit 60 notifies the personnel involved in the navigation of the ship by displaying the notification information c and the magnitude relationship dc delivered in this way.

  That is, according to the present embodiment, the true / false of the direction of the other ship indicated by the received wave Rc is determined with a predetermined accuracy without applying complicated radio navigation and satellite navigation that require a large amount of processing. The result of the determination is displayed on the display image of the operation display unit 60.

  Therefore, the information notified from the non-existent ship through the AIS is identified with low cost and high accuracy, and the result of the determination is provided for navigation support, and unnecessary hindrance to navigation by the camouflaged ship is avoided.

  In the present embodiment, when erroneous determinations due to the fact that not all axes of the linear antenna elements 12E-1 to 12E-6 are maintained vertically due to waves or ship swinging should be avoided. May be configured in any of the following forms.

(1) A rocking device and a mechanism for maintaining all the axes of the linear antenna elements 12E-1 to 12E-6 vertically are provided.
(2) A means for appropriately performing integration processing to reduce the possibility of erroneous determination is provided.

  Further, these swinging devices, mechanisms, and means may be configured to behave in conformity with entities such as topography, environmental conditions, weather conditions, and waves.

  Further, the arrangement and number of the linear antenna elements 12E-1 to 12E-6 on the vertical plane may be any as long as the arrival angle θc can be obtained with desired accuracy and speed.

In the present embodiment, the arrival angle θc is uniquely determined by the above-described processing performed by the direction finding processing unit 14.
However, such a determination of the magnitude relationship dc (c = 1 to n) based on the arrival angle θc may be realized by, for example, linking the units as follows.

(1) The power feeding control unit 13 controls the direction of the main lobe of the antenna 12 within a predetermined arrival angle range including the arrival angle θc (indicating the arrival direction of the received wave) indicated by “notification information c”. The search is performed by electronic beam forming under the section 11.

(2) Under this search, it is determined whether or not the received wave arriving from the corresponding other ship can be received at the maximum level.
Further, in the present embodiment, the azimuth angle Θc and the arrival angle θc that give the above-described deviation δc do not necessarily have to be obtained based on the received waves received at the same time, but individually in different periods on the time axis. You may obtain | require based on the received received wave.

[Second Embodiment]
The configuration of the present embodiment is different from the configuration of the first embodiment described above in that a control unit 11A is provided instead of the control unit 11.

  A feature of the present invention is that in the present embodiment, whether or not the transmission end for each received wave Rc (c = 1 to n) is located at a position indicated by notification information obtained by demodulation of the corresponding received wave is determined by: As described later, it is realized under the processing performed by the control unit 11A.

In the present embodiment, the direction finding processing unit 14 stops the operation and does not perform the above-described processing.
In addition, the power feeding control unit 13 sets the directivity of the antenna 12 in the horizontal direction to be non-directional, and shares the antenna 12 for reception and transmission.

  The TDMA receivers 43-1 and 43-2 obtain the received electric field strength Ec (c = 1 to n) individually corresponding to the corresponding other ship for any of the received waves Rc (c = 1 to n). The data is delivered to the control unit 11A via the modem unit 45.

Incidentally, the main memory of the control unit 11A has a distance conversion table 11T configured as follows, as shown in FIG.
(1) Surfaces individually corresponding to two transmission powers of 12.5 watts and 1 watt (both are nominal values) that can be applied to the transmission end of the received wave Rc (hereinafter referred to as “surface H” and “surface L”) Said).

(2) Both the surface H and the surface L are configured as a row of records having the following two fields.
-"Electric field strength" field indicating the received electric field strength that can be obtained by the TDMA receivers 43-1 and 43-2 with a predetermined accuracy (for example, 0.5 decibel steps)-Conversion of the value of the corresponding "Electric field strength" field A "relative distance" field that indicates the relative distance (of the corresponding other ship) given as a value

Here, it is assumed that such converted values are calculated in advance under the application of known values and standard values listed below.
(1) Transmit power deviation
(2) Gain and directivity of antenna 12

(3) Propagation loss and transmission characteristics of the wireless transmission path that can be formed with other ships (all or part of the distribution of topography and features that can intervene with other ships, weather conditions and their variations) May be taken into account.)

FIG. 4 is an operation flowchart of control in the second embodiment of the present invention.
Hereinafter, the operation of the present embodiment will be described with reference to FIG. 1, FIG. 3, and FIG.
11 A of control parts are the following about any of the received electric field intensity | strength Ec (c = 1-n) calculated | required separately by TDMA receiving part 43-1 and 43-2 about received wave Rc (c = 1-n). Process.

(1) The notification information c is converted into an array Ac (c = 1 to n) having a predetermined format and contents (step S1 in FIG. 4).

(2) Whether there is a record that satisfies the requirement that “the value of the“ field strength ”field is equal to the received field strength Ec with a desired accuracy” in either “surface H” or “surface L” of the conversion table 11T. It is determined whether or not (step S2 in FIG. 4).

(3) If there is no record that satisfies these requirements, the following processing is omitted.
(4) If there is a record corresponding to the opposite, the value Dc of the “relative distance” field of the record is acquired (step S3 in FIG. 4).

(5) The relative distance rc (c = 1 to n) of the position Lc (c = 1 to n) of the other ship included in the array Ac is obtained (step S4 in FIG. 4).
(6) A deviation δc (c = 1 to n) represented by the following equation is calculated with respect to the relative distance rc and the value Dc (step S5 in FIG. 4).
δc = | Dc−rc |

(7) A magnitude relation dc (c = 1 to n) between the deviation δc and a predetermined threshold th (≧ 0) is determined (step S6 in FIG. 4).

(8) The above-mentioned “notification information c” and the magnitude relation dc are delivered to the operation display unit 60 via the collector 50 in association with the received wave Rc (c = 1 to n) (step S7 in FIG. 4).

  The operation display unit 60 notifies the personnel involved in the navigation of the ship by displaying the notification information c and the magnitude relationship dc delivered in this way.

  That is, according to the present embodiment, the true / false of the distance converted (estimated) based on the received electric field strength of the received wave Rc can be obtained without applying a radio navigation or satellite navigation that requires a complicated and large amount of processing. The determination is made with a predetermined accuracy, and the result of the determination is displayed on the display image of the operation display unit 60.

  Therefore, the information notified from the ship that does not exist via the AIS is identified at low cost and with high accuracy, the result of the determination is provided for navigation support, and unnecessary hindrance to navigation by the camouflaged ship is avoided.

  In this embodiment, the presence / absence of a record that satisfies the requirement that “the value of the“ field strength ”field is equal to the received field strength Ec with a desired accuracy” indicates “surface H” and “surface L” in the conversion table 11T. Both of them are discriminated by referring to them.

  However, the presence / absence of such a record may be determined by, for example, each unit linking as follows.

[Behavior of each part in AIS transponder at transmitting end]
(1) The binary information indicating whether the transmission power of the transmission wave is 12.5 watts or 1 watt is generated by the control unit 11A.
(2) The modem unit 45 and the transmission unit 46 transmit the binary information to other ships as, for example, a binary broadcast message (Message 8).

[Behavior of the control unit 11A in the AIS transponder at the receiving end]
(1) The control unit 11A provides notification information corresponding to the received electric field strength Ec (c = 1 to n) obtained by the TDMA receiving units 43-1 and 43-2 for the received wave Rc (c = 1 to n). c is converted into a predetermined array Ac (c = 1 to n), respectively (step S1 in FIG. 4).

(2) It is determined whether or not the above-described binary information is included in any of the arrays Ac (c = 1 to n) (step S11 in FIG. 4).
(3) When such binary information is included, it is determined whether or not there is a record that satisfies the requirement that “the value of the“ field strength ”field is equal to the received field strength Ec with a desired accuracy” ( Hereinafter, prior to “record determination”, only one of the “surface H” and “surface L” of the conversion table 11T corresponding to the binary information is set as a reference target (step S12 in FIG. 4). ).

In the present embodiment, the “record determination” may be replaced by the following process performed by the control unit 11A.
(1) Reception received from another ship (AIS transponder) determined to be normal under a predetermined determination criterion among the received electric field strengths Ec obtained by the TDMA receivers 43-1 and 43-2 The electric field strength Ecn is identified.

(2) The position of the other ship included in the received wave Rcn (notification information cn) arriving from the other ship is converted into a relative distance rcn to the own ship.
(3) A pair of the relative distance rcn and the received electric field strength Ecn is recorded as a record in a record table (not shown) instead of the distance conversion table 11T, and sorted in descending order (ascending order) of the relative distance as appropriate.

(4) For each received wave Rc newly received subsequently, the received electric field strength Ec obtained by the TDMA receivers 43-1 and 43-2 and the position of the ship included in the corresponding notification information c A pair with the relative distance rc (hereinafter referred to as “determined pair”) is obtained.
(5) The above performance table is regarded as a scatter diagram (FIG. 3 (b)) given as a pair of the relative distance rcn and the received electric field strength Ecn, and the region where the results are distributed on the scatter diagram (a broken line of any width or It may be identified as a curved line).

  Furthermore, in the present embodiment, the conversion table 11T and the result table described above are a three-dimensional or higher table associated with all or a part of the following items related to both or one of the own ship and the other ship. It may be configured.

・ Deviation in transmission power of transmitted waves ・ Manufacturer, model, lot number, ship name, presence / absence of dangerous objects, distribution of obstacles on the deck, weather conditions, topography, and features related to the installed AIS transponder Distribution, relative azimuth

In the present embodiment, the antenna 12 may be replaced with the antenna 31AIS shown in FIG.
Furthermore, the above-described embodiments may be combined instead of being alone when the obstacles to navigation and avoidance of confusion caused by received waves coming from an innocent ship or the like are to be realized with higher accuracy.

  Further, such obstruction and scattering of navigation are combined with both or any one of the embodiments described above based on the invention related to the application on the same day as the present application, for example, “determination of the presence or absence of other ships and the accuracy thereof”. To achieve higher accuracy.

  Further, in each of the above-described embodiments, the transmitting end of the incoming received wave is not limited to the ship station, but may be an AIS transponder mounted on a land station, a buoy or the like.

Moreover, in each embodiment mentioned above, this invention is applied to AIS applied to a ship station or a land station.
However, the present invention is not limited to such an AIS, and can be similarly applied to any system or apparatus described below.

(1) “Artificial Satellite AIS” that can monitor the navigational status of ships located on the ocean more than 80 km away from the coast by installing an AIS receiver in an artificial satellite orbiting in a low orbit.

(2) AIS transponders mounted on aircraft that search and monitor at sea
(3) Broadcast Dependent Surveillance-Broadcast (ADS-B) system in which aircraft constantly reports its position and altitude to other aircraft and ground stations.

  Furthermore, the configuration of each embodiment described above is not limited to the configuration illustrated in FIG. 1. If the characteristic processes and functions of the present invention are realized under the above-described linkage, the functions and loads of each unit are not limited. Not only the form of distribution but also the multiple access method, frequency allocation, and channel configuration applied to wireless transmission may be any.

  Further, the present invention is not limited to the above-described embodiments, and various configurations of the embodiments are possible within the scope of the present invention, and any improvements may be made to all or some of the components.

11, 11A Control unit 12 Antenna 12E Linear antenna element 13 Feed control unit 14 Search processing unit 31AIS, 31GPS antenna 40 Transponder 41 (SW) Switch 42 (H) Hybrid 43 TDMA reception unit 44 DSC reception unit 45 Modulation / demodulation unit 46 Transmission Unit 47 GPS receiving unit 50 collector / distributor 60 operation display unit

Claims (3)

Azimuth calculating means for obtaining a relative azimuth of the position indicated by the radio signal that has arrived through the navigation surveillance automatic broadcasting system;
An arrival direction specifying means for specifying an arrival direction of the radio signal;
A radio signal discrimination device comprising: discrimination means for discriminating whether the radio signal or the position is true or false based on a difference between the azimuth and the arrival direction. In the radio signal discrimination device according to claim 1,
The arrival direction specifying means includes:
Based on the difference in phase corresponding to the difference in the length of the propagation path where these received waves arrive at the linear antenna elements, and the arrangement of these linear antenna elements, for the received waves arriving individually from different ships And determining the direction of arrival. In the radio signal discrimination device according to claim 1 ,
The arrival direction specifying means includes:
A radio signal discriminating apparatus characterized in that the arrival direction of the radio signal is specified under beamforming that scans the direction of a main lobe within a range of a predetermined azimuth including the azimuth.