JP6025189B2 - Rescue signal bearing detection device, rescue signal bearing detection method, and rescue signal bearing detection program - Google Patents

Description

  The present invention relates to a rescue signal azimuth detection device, a rescue signal azimuth detection method, and a rescue signal azimuth detection program, and in particular, has a mechanism for estimating the arrival azimuth of a rescue signal (radio wave) by using a MUSIC (Multiple Signal Classification) algorithm. The present invention relates to a rescue signal bearing detection device, a rescue signal bearing detection method, and a rescue signal bearing detection program.

  EPIRB (Emergency position indicating radio beacon) is a global system for maritime distress and safety, which is promoted by IMO (International Maritime Organization). ) Among the devices, it is an important device for detecting the position and sending the information in the case of distress and ship information.

  The EPIRB is a fixed buoy, and as described in Japanese Patent Application Publication No. 2004-514119 “Housing for emergency call transmitter” of Patent Document 1, when an emergency occurs and submerged, It automatically rises to the surface and periodically transmits two rescue signals with frequencies of 406.028 MHz and 121.5 MHz for 48 hours or more. The 406.028 MHz distress signal is derived from the Cospas-Sarsat system (Cosmicheskaya Systyema Poiska Avariynich Sudov-Search And Rescue Satellite Aided Tracking), a low altitude Earth Orbit Search and Rescue, The position can be determined by the Doppler effect obtained from the moving speed of the satellite and the rotation speed of the earth.

  The positioning information and the signal contents are received by the ground receiving station and then sent to the operation command center, where an alarm is issued by analyzing the occurrence of an emergency, nationality, ship name, and the like. The warning is relayed to a rescue coordination center that conducts SAR activities, and a complete rescue system is adopted anywhere in the world. On the other hand, the 121.5 MHz distress signal is a homing signal, and is mainly used for detecting a direction at a short distance, and facilitates searching from an aircraft, a ship, or the like existing near the distress site.

JP-T-2004-514119 (page 2-3)

  However, as described above, the conventional technique measures the Doppler frequency when the satellite receives the rescue signal from the EPIRB by performing positioning by Doppler shift, and the latitude / longitude of the position where the rescue signal is transmitted. Is to calculate. For this reason, when the radio wave from EPIRB is received by the satellite, the distance to the satellite is known by the Doppler effect of the radio wave frequency, but two candidate beacon positions are detected. Therefore, in order to distinguish which one of the two detected locations is the real position where the rescue signal is transmitted, the detection is performed also in another satellite, and two candidates detected in another satellite are detected. Of these, an identification method is required in which the true position is the one that matches the two positions detected by the previous satellite.

  Further, in such positioning by Doppler shift, there is a possibility that the beacon position cannot be specified with high accuracy due to a correction error in satellite orbit prediction, an error due to insufficient frequency stability on the beacon side, and the like. Furthermore, in the LEOSAR system, the satellite does not always exist in the sky, so in the worst case, there is a possibility that a time lag of about 2 hours will occur until the satellite reaches the sky and receives the distress signal. is there. On the other hand, at the time of ship disaster, since a quick rescue operation is necessary, it is indispensable to avoid the case where the above-mentioned rescue signal cannot be received.

  In addition, since the 121.5 MHz homing signal is not input with ID information for specifying the transmission source, it cannot be identified whether it is a rescue signal from a beacon or a signal from another aircraft or the like. . Therefore, even if a homing signal is detected, it cannot be confirmed whether it is a real distress or an erroneous call.

(Object of the present invention)
The present invention has been made in view of such circumstances, and even if a rescue signal can be received from a beacon that can reliably receive a rescue signal and does not have position information, the direction of arrival of the rescue signal Another object of the present invention is to provide a rescue signal azimuth detecting device, a rescue signal azimuth detecting method, and a rescue signal azimuth detecting program capable of quickly measuring a firing position of a rescue signal.

  In order to solve the above-described problems, the rescue signal bearing detection device, the rescue signal bearing detection method, and the rescue signal bearing detection program according to the present invention mainly adopt the following characteristic configuration.

  (1) A rescue signal azimuth detection device according to the present invention is a rescue signal azimuth detection device that detects the azimuth of a rescue signal transmitted from an EPIRB (Emergency position indicating radio beacon), receives a radio signal, and receives the rescue signal. A receiving unit that generates an IQ signal from which unnecessary components are removed for detection, and calibration of the receiving operation in the receiving unit based on the analysis result of the frequency of the generated IQ signal, and the symbol of the IQ signal Based on the conversion result to the rate, it is analyzed whether or not the radio signal received by the receiving unit is a rescue signal. If it is determined that the radio signal is a rescue signal, the rescue message included in the rescue signal is An analyzing unit that demodulates, an azimuth measuring unit that measures an arrival direction of a signal that is determined to be a rescue signal, the rescue message demodulated by the analysis unit, and the A display unit position measuring unit displays the arrival direction of the distress signal measured, characterized in that it constitutes at least contain.

  (2) A rescue signal direction detection method according to the present invention is a rescue signal direction detection method for detecting a direction of a rescue signal transmitted from an EPIRB (Emergency position indicating radio beacon). A reception step of generating an IQ signal from which unnecessary components are removed for detection of the signal, and a calibration of the reception operation in the reception step based on the analysis result of the frequency of the generated IQ signal, and the symbol of the IQ signal Based on the conversion result to the rate, it is analyzed whether or not the radio signal received in the reception step is a rescue signal. If it is determined that the radio signal is a rescue signal, the rescue message included in the rescue signal is An analyzing step for demodulating, an azimuth measuring step for measuring the arrival azimuth of the signal determined to be a rescue signal by the analyzing step unit, and the solution And a display step portion of the step is displaying the arrival direction of the distress signals the azimuth measuring step and the rescue message demodulated measured, characterized in that it constitutes at least contain.

  (3) A rescue signal direction detection program according to the present invention is characterized in that at least the rescue signal direction detection method described in (2) is implemented as a program executable by a computer.

  According to the rescue signal bearing detection apparatus, rescue signal bearing detection method, and rescue signal bearing detection program of the present invention, the following effects can be achieved.

  That is, in the present invention, it becomes possible to always receive a rescue signal periodically transmitted from the EPIRB, so it is not necessary to depend on the LEOSAR system, and the LEOSAR system is not functioning normally. Even when there is no satellite in the sky above the beacon and the beacon position cannot be specified, the rescue signal is directly received, the rescue signal is analyzed, and the arrival direction of the rescue signal. It becomes possible to measure the firing position of the rescue signal.

It is a block block diagram which shows an example of the block configuration of the rescue signal direction detection apparatus by this invention. It is a block block diagram for demonstrating the further detailed structure of the block structure of the rescue signal direction detection apparatus shown in FIG. FIG. 3 is a flowchart for explaining an example of the operation of the receiving unit 1 in the rescue signal azimuth detecting device shown in FIGS. 1 and 2; FIG. It is a flowchart for demonstrating an example of operation | movement of the analysis part 11 in the rescue signal azimuth | direction detection apparatus shown in FIG. 1, FIG. FIG. 3 is a flowchart for explaining an example of the operation of an azimuth measuring unit 16 in the rescue signal azimuth detecting device shown in FIGS. 1 and 2; FIG. It is a flowchart for demonstrating an example of operation | movement of the display part 20 in the rescue signal azimuth | direction detection apparatus shown in FIG. 1, FIG. It is a schematic diagram which shows an example regarding arrangement | positioning of the antenna element shown in FIG. It is a table which shows the format of the rescue signal transmitted periodically from EPIRB. It is a schematic diagram for demonstrating a mode that the intersection in each azimuth | direction of the rescue signal received in a different point is specified as a firing position of a rescue signal.

  Preferred embodiments of a rescue signal bearing detection device, rescue signal bearing detection method, and rescue signal bearing detection program according to the present invention will be described below with reference to the accompanying drawings. In the following description, the rescue signal direction detection device and the rescue signal direction detection method according to the present invention will be described. However, the rescue signal direction detection method is implemented as a rescue signal direction detection program executable by a computer. Needless to say, the rescue signal direction detection program may be recorded on a computer-readable recording medium.

(Features of the present invention)
Prior to the description of the embodiments of the present invention, an outline of the features of the present invention will be described first. The present invention was made in view of a rescue signal periodically transmitted from an EPIRB (Emergency position indicating radio beacon), and the rescue signal azimuth detecting device detects a radio signal for the first time. When performing the calibration of the reception operation of the reception unit inside the rescue signal azimuth detection device based on the result of calculating the frequency of the radio signal, the calibration of the reception operation of the internal reception unit is completed Rescue message included in the rescue signal when the radio signal detected after the second time is analyzed to determine whether or not it matches the format of the rescue signal and the radio signal is detected as a rescue signal. A demodulating analysis unit, an azimuth measuring unit for measuring the arrival direction of the rescue signal, a demodulated rescue message, and the measured arrival direction of the rescue signal are displayed. Identify the firing position of 該救 flame signal, and mainly characterized in that it includes a display unit for displaying the firing position, at least.

  Here, in order to detect a rescue signal from the EPIRB, a process for determining whether or not the signal is a rescue signal when a radio signal having an amplitude exceeding a threshold provided in advance in the rescue signal bearing detection device is detected. The frequency of the radio signal is calculated by performing Fourier transform on the detected radio signal, and the radio signal is detected by performing synchronous detection on the radio signal based on the calculated frequency. It is also a main feature of the present invention that when a bit synchronization or frame synchronization signal included in the signal is detected, the wireless signal is regarded as a rescue signal and is determined to have been detected. .

  In the present invention, a MUSIC (Multiple Signal Classification) algorithm is used to measure the arrival direction of the rescue signal. To accurately measure the arrival direction of the rescue signal, the rescue signal direction is used. It is necessary to calibrate the receiving operation of the receiving system of the detection apparatus and to correct the correlation matrix in accordance with the frequency of the rescue signal received. Therefore, in the present invention, paying attention to the fact that the rescue signal from EPIRB is a burst signal transmitted periodically, a calibration step for calibrating the reception operation of the rescue signal bearing detection device, One of the features is that the arrival direction of the rescue signal is measured by receiving the rescue signal a plurality of times in two stages, that is, an analysis step for performing analysis and detection.

  Furthermore, in the present invention, the received radio signal is buffered for a predetermined time in a memory or other storage device in order to measure the direction of the rescue signal by receiving the rescue signal multiple times. When a rescue signal is detected, a radio signal corresponding to the detected rescue signal is extracted from a storage device such as the memory, and a correlation matrix is calculated. Based on the calculated correlation matrix and the detected frequency One of the features is that the arrival direction of the rescue signal is measured by the MUSIC algorithm.

  Furthermore, in the present invention, in order to measure the launch position of the rescue signal, the point where the rescue signal is received and the arrival direction of the rescue signal are stored for a predetermined elapsed time from the time of the first detection. In addition, when a plurality of rescue signals having the same frequency are detected until the predetermined elapsed time has passed, the rescue signal is calculated by calculating the intersection of the extension lines of the directions for each of the detected rescue signals. One of the features is to specify the launch position.

  By adopting the above mechanism, in the present invention, since the rescue signal transmitted periodically is directly received, unlike the conventional LEOSAR system, it is assumed when the rescue signal is detected by the satellite. The arrival direction and launch position of the rescue signal can be measured in real time without causing a time lag (about 2 hours).

(Configuration example of embodiment of the present invention)
Next, a configuration example of the embodiment of the rescue signal direction detection device according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram illustrating an example of a block configuration of a rescue signal direction detection device according to the present invention, and FIG. 2 illustrates a more detailed configuration of the block configuration of the rescue signal direction detection device illustrated in FIG. It is a block block diagram for this.

  As shown in FIG. 1, the rescue signal azimuth detection device according to an embodiment of the present invention includes at least a reception unit 1, an analysis unit 11, an azimuth measurement unit 16, and a display unit 20.

  That is, in the rescue signal azimuth detecting device of FIG. 1, after the wireless signal (rescue signal) transmitted periodically is received by the receiving unit 1, the analysis unit 11 receives the received wireless signal (rescue signal). The frequency is calculated, and the reception operation of the reception unit 1 in the rescue signal direction detection device is calibrated based on the calculated result.

  After calibration of the receiving unit 1 in the rescue signal azimuth detection device, when the radio signal (rescue signal) is received again by the receiving unit 1, the analysis unit 11 synchronizes the received radio signal with the synchronization bit of the rescue signal, It is confirmed whether or not a frame is included. If a synchronization bit and a synchronization frame of a rescue signal are included, the received radio signal is detected as a rescue signal, and the analysis unit 11 relates to the detected rescue signal. And the azimuth measuring unit 16 measures the arrival direction of the rescue signal.

  Thereafter, the rescue message demodulated by the analysis unit 11 and the arrival direction of the rescue signal measured by the orientation measurement unit 16 are displayed on the display unit 20.

  Further, the display unit 20 wirelessly corresponds to the arrival direction of the rescue signal measured by the direction measuring unit 16 and the detected rescue signal until the predetermined elapsed time elapses after the rescue signal is first detected. When the point where the signal is received is stored in a memory or the like, and the azimuth measuring unit 16 has calculated a plurality of arrival azimuths of rescue signals of the same frequency until the predetermined elapsed time has elapsed, The rescue signal launch point is calculated, and the calculated rescue signal launch point is displayed.

  In other words, by calculating the intersection where the extension lines of the respective azimuths of the plurality of rescue signal reception points stored in the memory or the like intersect with each other, it is displayed that the rescue signal emission position exists at the intersection. To do.

  In the present embodiment, the display unit 20 is provided with a memory or the like for storing the arrival direction of the rescue signal measured by the orientation measurement unit 16 and the point where the radio signal corresponding to the detected rescue signal is received. Although the case will be described, the present invention is not limited to such a case. For example, such a memory or the like is arranged on the side of the azimuth measuring unit 16 for measuring the arrival direction of the rescue signal, and the predetermined elapsed time determined in advance from the time when the rescue signal is first detected on the azimuth measuring unit 16 side. You may make it memorize | store until it passes. In such a case, when the arrival directions of a plurality of rescue signals having the same frequency are measured until the predetermined elapsed time elapses, the orientation measurement unit 16 at each reception point of the plurality of rescue signals. By calculating the intersection where the extension lines of the rescue signal azimuth intersect each other, the rescue signal launch position may be calculated and output to the display unit 20 together with the arrival direction of the rescue signal.

  Next, a more detailed internal configuration of each block shown in FIG. 1 will be described with reference to FIG. As shown in FIG. 2, the receiver 1 of the rescue signal azimuth detecting device shown in FIG. 1 includes an antenna element 2, a band pass filter 3, an amplifier 4, an amplitude controller 5, a mixer 6, a low pass filter 7, An A / D converter 8, an IQ separator 9, and a decimation filter 10 are configured to receive at least a radio signal and output a baseband IQ signal.

  The analysis unit 11 includes at least a reception level determination unit 12, a Fourier transformer 13, a PLL 14, and a symbol demodulator 15. The analysis unit 11 analyzes the frequency of the radio signal received by the reception unit 1, and When calibrating the conversion process for the mixer 6 and analyzing whether the radio signal received after the calibration corresponds to a rescue signal, and determining that the radio signal is a rescue signal, the radio signal (rescue Signal) is demodulated, and a rescue message included in the radio signal (rescue signal) is output to the display unit 20.

  The azimuth measuring unit 16 includes at least a storage unit 17, a correlation matrix generator 18, and a MUSIC computing unit 19, and the radio signal received by the receiving unit 1 when the analysis unit 11 detects a rescue signal. Among the signals, the arrival direction of the radio signal corresponding to the detected rescue signal is measured, and the measured arrival direction of the radio signal (rescue signal) is output to the display unit 20.

  The display unit 20 includes at least a message output unit 21 and an azimuth output unit 22. The display unit 20 includes a message of a radio signal (rescue signal) demodulated by the analysis unit 11 and a radio signal (rescue) measured by the azimuth measurement unit 16. The arrival direction of the signal is displayed. In addition, if multiple rescue signals of the same frequency are received at different points after the first rescue signal is detected and a certain elapsed time has elapsed, the launch point of the radio signal (rescue signal) is calculated. Then, the emission position of the calculated radio signal (rescue signal) is displayed.

(Description of operation of embodiment)
Next, an example of the operation of the rescue signal bearing detection apparatus shown in FIGS. 1 and 2 as an embodiment of the present invention will be described with reference to the flowchart of FIG. FIG. 3 is a flowchart for explaining an example of the operation of the rescue signal azimuth detecting device shown in FIGS. 1 and 2. FIG. 3 (A) shows the receiver 1, and FIG. 3 (B) shows the analysis. 3C shows an example of the operation of the azimuth measuring unit 16, and FIG. 3D shows an example of the operation of the display unit 20, respectively.

  In the flowchart of FIG. 3, first, an example of the operation of the receiving unit 1 will be described based on FIG. The antenna element 2 constituting the receiving unit 1 receives a radio signal and outputs it as a received signal to the band pass filter 3 (step S1). As shown in FIG. 4, the antenna element 2 includes an odd number of elements (in the example of FIG. 4, the case of three elements including three antenna elements 2a, 2b, and 2c) is circular. Arranged at equal intervals on the circumference, the two-dimensional orientation can be measured from the reference point O located at the center of the circle. Here, FIG. 4 is a schematic diagram showing an example of the arrangement of the antenna elements 2 shown in FIG. 2, and the three antenna elements 2a, 2b, and 2c are rotated at equal intervals (120 ° each on the same circumference). An example of arrangement at intervals) is shown.

  When received signals from each of the three antenna elements 2a, 2b, and 2c are input, the band-pass filter 3 performs band limitation to extract only frequency components effective for the received signals, and the received signals are received. Unnecessary components such as noise included in each of the three systems of received signals are removed and output to the amplifier 4 (step S2). When the received signal from the band pass filter 3 is input, the amplifier 4 amplifies the received signal based on a predetermined amplification factor and outputs the amplified signal to the amplitude controller 5 (step S3).

  When the reception signal from the amplifier 4 is input, the amplitude controller 5 determines whether or not the reception signal exceeds a predetermined amplitude threshold value. When the amplitude threshold value is exceeded, The signal is treated as an effective radio signal for determining whether or not it is a rescue signal, and the amplitude of the signal is adjusted to an appropriate amplitude value so as to be suitable for subsequent processing and output to the mixer 6 ( Step S4). Thereafter, the mixer 6 mixes the received signal output from the analysis unit 11 with the received frequency, thereby converting the received signal from the amplitude controller 5 so that the frequency of the received signal is suitable for subsequent processing. And output to the low-pass filter 7 (step S5).

  When the reception signal from the mixer 6 is input, the low-pass filter 7 removes unnecessary waves generated when the frequency of the reception signal is converted, and the A / D converter 8 receives the signal. (Step S6). Thereafter, the A / D converter 8 performs processing for converting the received signal from the low-pass filter 7 from an analog signal to a digital signal, and outputs it to the IQ separator 9 (step S7). .

  In the IQ separator 9, the received signal from the A / D converter 8 is converted into a real signal (I signal) and a complex signal (Q signal) and output to the decimation filter 10. (Step S8). When the IQ signal from the IQ separator 9 is input, the decimation filter 10 performs decimation processing on the IQ signal, thereby converting the frequency of the IQ signal to be suitable for subsequent processing, It outputs to the analysis part 11 and the direction measurement part 16 (step S9).

  Next, an example of the operation of the analysis unit 11 that has received three systems of IQ signals from the decimation filter 10 of the reception unit 1 will be described with reference to the flowchart of FIG. In the reception level determination unit 12 of the analysis unit 11, the amplitude is calculated for any one of the three IQ signals from the decimation filter 10 of the reception unit 1, and the IQ signal from the decimation filter 10 is calculated. Is determined (step S11), and if it is determined that an IQ signal has been input (YES in step S11), the fact is notified to the Fourier transformer 13. That is, it is determined whether or not the amplitude of the received radio signal exceeds a predetermined threshold level. If the received radio signal is below the threshold level, the received radio signal is invalidated and exceeds the threshold level. Is treated as an effective radio signal for determining whether or not it is a rescue signal, and a process equivalent to the process of notifying the fact to the Fourier transformer 13 is performed.

  In the Fourier transformer 13, if it is determined that the IQ signal from the decimation filter 10 of the reception unit 1 is input as the determination result from the reception level determination unit 12, 3 from the decimation filter 10 of the reception unit 1. Fourier transform is performed on any one of the system IQ signals, the frequency of the received signal (radio signal) received by the antenna element 2 in step S1, and the mixer 6 of the receiver 1 and The data is output to the PLL 14 of the analysis unit 11 (step S12). In the mixer 6 of the receiving unit 1 that has received the reception frequency of the reception signal from the Fourier transformer 13, the conversion process using the reception frequency of the reception signal received from the Fourier transformer 13 is performed thereafter in step S 5. The receiving operation is calibrated.

  On the other hand, in the PLL 14, when the reception frequency of the reception signal from the Fourier transformer 13 is input, synchronous detection is performed on the IQ signal from the decimation filter 10, and the frequency of the IQ signal is converted into a symbol rate. The data is output to the symbol demodulator 15 (step S13). When an output signal converted into a symbol rate is input from the PLL 14, whether or not the symbol demodulator 15 can detect the bit synchronization 52 and the frame synchronization 53 of the rescue signal shown in FIG. 4 from the output signal. Is determined (step S14). FIG. 4 is a table showing a format of a rescue signal periodically transmitted from the EPIRB. The unmodulated carrier 51, bit synchronization 52, frame synchronization 53, information bit 54, error correction code 55, and emergency code 56 are shown in FIG. It is shown that it is composed of.

  If the bit synchronization 52 and the frame synchronization 53 of the rescue signal shown in FIG. 4 can be detected (YES in step S14), it is determined that the rescue signal has been detected, and the determination result is used as the direction measurement unit 16. Is output to the storage device 17 (step S15). Here, when the bit synchronization 52 and the frame synchronization 53 of the rescue signal can be detected, a radio signal having the same frequency is received after the reception operation related to the conversion process of the mixer 6 in step S5 is calibrated. This is the case. Furthermore, when bit synchronization and frame synchronization can be detected (YES in step S14), the symbol demodulator 15 of the analysis unit 11 includes the rescue signal information bit 54 shown in FIG. A rescue signal message (rescue message) is extracted and output to the message output unit 21 of the display unit 20 (step S16).

  Next, an example of the operation of the azimuth measuring unit 16 that has received the determination result knowledge that the rescue signal has been detected from the symbol demodulator 15 of the analyzing unit 11 will be described with reference to the flowchart of FIG. The azimuth measurement unit 16 performs an operation of storing the IQ signal from the decimation filter 10 of the reception unit 1 in the storage unit 17 (step S21), and also indicates that a rescue signal has been detected from the symbol demodulator 15 of the analysis unit 11. It is monitored whether the determination result has been notified (step S22).

  When a determination result indicating that the rescue signal has been detected is received from the symbol demodulator 15 of the analysis unit 11 (YES in step S22), the three IQ signals stored in the storage unit 17 of the azimuth measurement unit 16 are stored. The three IQ signals corresponding to the rescue signal are extracted from the inside and output to the correlation matrix generator 18 (step S23).

  When three systems of IQ signals corresponding to the rescue signal are output, the correlation matrix generator 18 calculates a correlation matrix and outputs the correlation matrix to the MUSIC calculator 19 (step S24). In the MUSIC calculator 19, the MUSIC calculation is performed on the correlation matrix output from the correlation matrix generator 18, the arrival direction of the rescue signal is calculated, and output to the direction output unit 22 of the display unit 20. (Step S25).

  Next, a flowchart of FIG. 3D shows an example of the operation of the display unit 20 that receives the rescue message from the symbol demodulator 15 of the analysis unit 11 and the arrival direction of the rescue signal from the MUSIC computing unit 19 of the direction measurement unit 16. Will be described. First, when a rescue message is received from the symbol demodulator 15 of the analysis unit 11, the rescue message is displayed on the message output unit 21 of the display unit 20 (step S31).

  Further, when the arrival direction of the rescue signal is received from the MUSIC computing unit 19 of the orientation measurement unit 16, the orientation output unit 22 of the display unit 20 receives a predetermined constant from the time when the radio signal corresponding to the first rescue signal is received. Until the elapsed time elapses, the location where the radio signal corresponding to the rescue signal is received and the arrival direction of the rescue signal are stored in a memory or the like, and the arrival direction of the rescue signal is displayed (step S32). ).

  Next, the azimuth output unit 22 of the display unit 20 periodically transmits from the EPIRB until the predetermined elapsed time has elapsed by referring to the stored content stored in the memory or the like. Whether or not a plurality of rescue signals having the same frequency are received, and a plurality of information relating to the arrival directions of the rescue signals are received and displayed from the MUSIC computing unit 19 of the bearing measurement unit 16 at a plurality of different points as the rescue signal bearing detection device. (Step S33). When a plurality of pieces of information regarding arrival directions of rescue signals of the same frequency are received and displayed (YES in step S33), as shown in FIG. 6, extension lines of the respective directions of rescue signals received at a plurality of different points. The intersection at is calculated (step S34). Thereafter, the intersection where the extended lines of the plurality of directions received at the plurality of points intersect with each other is specified and displayed as the rescue signal emission position (step S35).

  Here, FIG. 6 is a schematic diagram for explaining how the intersections in the respective directions of the rescue signals received at different points are identified as the rescue signal transmission points. In FIG. 6, when a rescue signal is received at two points of the first point 61 and the second point 62 with respect to the movement in the traveling direction 60 of a ship or the like carrying the rescue signal bearing detection device, A state in which the target 63 serving as a position is specified is shown. That is, at the first point 61, there is a rescue signal emission point on the extension line of the first direction θ <b> 1 with respect to the traveling direction 60, and at the second point 62, the second direction θ <b> 2 extends with respect to the traveling direction 60. Since there is a rescue signal emission point on the line, it is calculated that the rescue signal emission position of the target 63 is at the intersection where the extension line of the first direction θ1 and the extension line of the second direction θ2 intersect each other. it can.

  The configuration of the preferred embodiment of the present invention has been described above. However, it should be noted that such embodiments are merely examples of the present invention and do not limit the present invention in any way. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Reception part 2 Antenna element 2a Antenna element 2b Antenna element 2c Antenna element 3 Band pass filter 4 Amplifier 5 Amplitude controller 6 Mixer 7 Low pass filter 8 A / D converter 9 IQ separator 10 Decimation filter 11 Analysis part 12 Reception level judgment unit 13 Fourier transformer 14 PLL
15 Symbol demodulator 16 Direction measuring unit 17 Storage unit 18 Correlation matrix generator 19 MUSIC computing unit 20 Display unit 21 Message output unit 22 Direction output unit 51 Unmodulated carrier 52 Bit synchronization 53 Frame synchronization 54 Information bit 55 Error correction code 56 Emergency Code 60 Traveling direction 61 First point 62 Second point 63 Target O Reference point θ1 First direction θ2 Second direction

Claims (10)

A rescue signal azimuth detecting device for detecting the azimuth of a rescue signal transmitted from an EPIRB (Emergency position indicating radio beacon), which receives a radio signal and removes an IQ signal from which unnecessary components are removed for detection of the rescue signal. Based on the generated reception unit and the frequency analysis result of the generated IQ signal, the reception operation in the reception unit is calibrated. After the calibration is completed, the IQ signal is converted into a symbol rate. Analyzing the radio signal received by the receiving unit, if it is determined to be a rescue signal, an analysis unit for demodulating a rescue message included in the rescue signal; and An azimuth measuring unit that measures the arrival azimuth of a signal that the analysis unit determines to be a rescue signal, the rescue message demodulated by the analysis unit, and the rescue measured by the azimuth measurement unit Mayday azimuth detecting apparatus characterized by arrival and a display unit for displaying the azimuth constitutes at least include the issue.   When a plurality of rescue signals having the same frequency are detected from when the radio signal corresponding to the first rescue signal is received until a predetermined elapsed time elapses, each of the plurality of rescue signals arrives. 2. The rescue according to claim 1, wherein a position where the rescue signal is fired is identified and displayed on the display unit based on a direction and a point where the radio signal corresponding to each rescue signal is received. Signal orientation detection device.   When the analysis unit detects that the bit synchronization and frame synchronization of the EPIRB rescue signal are included as a conversion result of the IQ signal to the symbol rate, the received signal corresponding to the IQ signal is a rescue signal. 3. The rescue signal azimuth detecting device according to claim 1 or 2, wherein it is determined that there is one.   The azimuth measuring unit uses a MUSIC algorithm by calculating a correlation matrix related to the IQ signal from the receiving unit determined as a rescue signal in the analyzing unit after calibrating the receiving operation of the receiving unit. The rescue signal azimuth detecting apparatus according to claim 1, wherein an arrival azimuth of the rescue signal is calculated.   The analysis unit determines whether the amplitude of the received radio signal exceeds a predetermined threshold level, and if the amplitude exceeds the threshold level, determines whether the signal is a rescue signal 5. The process according to claim 1, wherein a process for determining whether the rescue signal is a valid radio signal is performed, and the received radio signal is invalidated if the signal is equal to or lower than the threshold level. The rescue signal bearing detection device according to any one of the above. A rescue signal direction detection method for detecting the direction of a rescue signal transmitted from an EPIRB (Emergency position indicating radio beacon), which receives a radio signal and removes an IQ signal from which unnecessary components are removed for detection of the rescue signal. Based on the generated reception step and the analysis result of the frequency of the generated IQ signal, the reception operation in the reception step is calibrated, and after the calibration is completed , based on the conversion result of the IQ signal to the symbol rate. Analyzing whether the radio signal received in the receiving step is a rescue signal, and determining that the radio signal is a rescue signal, an analysis step for demodulating a rescue message included in the rescue signal; An azimuth measuring step for measuring the arrival azimuth of the signal determined to be a rescue signal by the analysis step unit, and the rescue memorized by the analysis step. And a display step portion sage and the direction measuring step displays the arrival direction of the distress signal measured, mayday azimuth detection method characterized in that it constitutes at least contain.   When a plurality of rescue signals having the same frequency are detected from when the radio signal corresponding to the first rescue signal is received until a predetermined elapsed time elapses, each of the plurality of rescue signals arrives. The rescue according to claim 6, wherein a launch position of the rescue signal is identified and displayed in the display step based on an azimuth and a point where a radio signal corresponding to each rescue signal is received. Signal orientation detection method.   In the analysis step, when it is detected that bit synchronization and frame synchronization of the EPIRB rescue signal are included as a conversion result of the IQ signal to the symbol rate, the received signal corresponding to the IQ signal is a rescue signal. The rescue signal azimuth detection method according to claim 6 or 7, wherein it is determined that there is a rescue signal.   The azimuth measurement step uses a MUSIC algorithm by calculating a correlation matrix related to the IQ signal from the reception step determined as a rescue signal in the analysis step after calibrating the reception operation of the reception step. 9. The rescue signal direction detection method according to claim 6, wherein an arrival direction of the rescue signal is calculated.   10. A rescue signal direction detection program, wherein the rescue signal direction detection method according to claim 6 is implemented as a program executable by a computer.

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