CN115421166A - Interference source identification and monitoring method of international search and rescue satellite system - Google Patents

Interference source identification and monitoring method of international search and rescue satellite system Download PDF

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Publication number
CN115421166A
CN115421166A CN202211067019.9A CN202211067019A CN115421166A CN 115421166 A CN115421166 A CN 115421166A CN 202211067019 A CN202211067019 A CN 202211067019A CN 115421166 A CN115421166 A CN 115421166A
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signal
interference
satellite
bits
interference source
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徐京渝
万千
赵辉
高平
孔祥娇
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China Transport Telecommunications And Information Center
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China Transport Telecommunications And Information Center
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42—Determining position

Abstract

A method for identifying and monitoring interference sources of an international search and rescue satellite system comprises the following steps that a ground receiving station receives a radio signal which is sent by a satellite and contains a normal signal and an interference signal, and then the interference sources are identified and monitored according to the following steps: step 100, determining that the signal transmission time is more than 520ms +/-1% as an interference signal; step 200, further judging the coding format: firstly, judging that the bit synchronization identification of the 1 st to 15 th bits of the signal and the frame synchronization identification of the 16 th to 24 th bits of the signal are not synchronous and consistent and can be judged as an interference signal; secondly, if the 25 th to 36 th bits do not completely accord with the rule, the signal is judged to be an interference signal; step 300, the doppler position of the interfering signal is determined. The invention adopts globally deployed LUT ground reception to realize data reception of satellites in different places, has higher coverage area and real-time performance and accurate positioning precision, is beneficial to searching of interference sources, thereby reducing the interference of the interference sources on the signals received by the satellites and the ground stations and improving the positioning precision and the positioning time efficiency of the position marker in danger.

Description

Interference source identification and monitoring method of international search and rescue satellite system
Technical Field
The invention belongs to the technical field of satellite communication, and particularly relates to an interference source identification and monitoring method based on a 406.0-406.1MHz frequency band of an international search and rescue satellite system.
Background
The international Search and Rescue Satellite system (COSPAS-SARSAT, comicheskekaya Sistema PoiskaAvariynichSudov-Search and research Satellite) is an important component of the Global Maritime Distress and Safety System (GMDSS) of the International Maritime Organization (IMO), and is a system for carrying out distress alarm information service by using satellites in the global scope.
Referring to fig. 1, a schematic diagram of an international search and rescue satellite system is shown, where the international search and rescue satellite system mainly includes a position indicator 1, a satellite 2, and a ground receiving station, where the ground receiving station is divided into a Local user terminal 3 (LUT) and a Mission Control Center 4 (MCC). The distress indication marker 1 is mainly arranged on a ship, an airplane or carried by a person, and sends an alarm signal manually or automatically in distress. Satellite 2 mainly includes a plurality of GNSS (Global navigation satellite system) satellites and low orbit satellites distributed globally, and LUT3 and MCC4 are distributed in 45 countries and regions globally.
The main operation process of the international search and rescue satellite system comprises the following steps: the distress location indicator 1 sends an alarm signal to the satellite 2 when in distress, the satellite 2 forwards the alarm signal to the local user terminal 3, the local user terminal 3 receives, decodes and calculates the received alarm signal, sends the relevant information of the distress location indicator identification code and the location data to the MCC4, the MCC4 confirms the position in distress and the distress information to generate an alarm message (SIT-185), and then the alarm message is distributed to the search and rescue center 5 to assist search and rescue personnel to rapidly carry out rescue work according to the position in distress and the information.
The international search and rescue satellite organization stipulates that all ship, aviation and land users around the world must be equipped with and use a unified 406MHz distress signpost. When a ship, an airplane or an individual encounters life danger, the distress indication beacon 1 is automatically or manually started, 406.0-406.1MHz frequency band signals are transmitted, the satellite 2 receives the signals, the signals are received and decoded by the LUT3, and the MCC4 determines the distress coordinate position and beacon information and informs the relevant search and rescue departments 5 to search and rescue. The 406.0-406.1MHz band has been registered by the International Telecommunications Union (ITU) and uses dedicated frequencies for search and rescue, which are not freely available. However, the phenomenon of illegally using the 406.0-406.1MHz frequency band exists all over the world, the illegal transmission of the 406.0-406.1MHz frequency band can cause interference to the transmission of the distress location mark and influence the reception of distress signals of a ground station, so that the performance is reduced, the quality is deteriorated, the positioning precision is reduced, information is wrong or even lost, the interference with larger power can cover the 406MHz distress location mark signals, the distress search and rescue time effectiveness is influenced, and the safe search and rescue of people is delayed.
Therefore, an interference source monitoring method is urgently needed to identify the interference source in the 406.0-406.1MHz frequency band and acquire the transmitting position of the interference source.
Disclosure of Invention
Therefore, the invention aims to provide an interference source identification and monitoring method of an international search and rescue satellite system, which is used for identifying an interference source in a 406.0-406.1MHz frequency band and acquiring the emission position of the interference source.
In order to achieve the above object, the present invention provides an interference source identification and monitoring method for an international search and rescue satellite system, wherein the international search and rescue satellite system adopts a low-orbit search and rescue satellite system, the system comprises at least one satellite and at least one ground receiving station, each ground receiving station comprises a local user terminal and a task control center, the ground receiving station receives a radio signal which is transmitted by the satellite and contains a normal signal and an interference signal, and then the interference source identification and monitoring are performed according to the following steps:
step 100, judging that the signal is an interference signal when the signal emission time is more than 520ms +/-1%, and otherwise, carrying out the next step;
step 200, further judging the coding format:
firstly, judging bit synchronization identification of 1 st to 15 th bits and frame synchronization identification bits of 16 th to 24 th bits of the signal, wherein if the bit synchronization identification and the frame synchronization identification bits do not accord with each other, the signal can be judged to be an interference signal;
secondly, the 25 th bit of the normal signal is marked as a format mark, the 26 th bit of the normal signal is marked as 1, the 27 th to 36 th bits are country codes, and if the 25 th to 36 th bits do not completely accord with the rules, the normal signal is judged to be an interference signal;
step 300, measuring the Doppler position of the interference signal:
positioning by adopting a plurality of satellites and a plurality of ground receiving stations to realize positioning of an interference source; and distributing the monitored interference source information including the transmission time, the transmission frequency, the transmission coordinate position and the like of the interference source through the task control center. A plurality of global 40 task control centers are communicated through an FTP network, and a plurality of low-orbit ground receiving systems and data detected by different satellites are adopted for positioning, so that the position confirmation of an interference source is realized.
Further comprising step 400, the transmission frequency of the interference source is confirmed:
if the interference sources at the same position are monitored within 72 hours, the interference sources can be identified as the same interference source, and detection counting is carried out; once the position is changed or not monitored within 72 hours, another interference source is identified, and the detection counting is carried out again.
Wherein the bit synchronization flag of the 1 st to 15 th bits of the signal in step 200 is consistent with the bit synchronization flag of the 16 th to 24 th bits of the signal, that is, the first 24 bits of the signal are 111111111111111000101111; or 111111111111111111011010000 in self-test mode. Bit 25 defines the message type, "0" for short message format or "1" for long message format.
The main formula adopted in the step 300 for determining the doppler position of the interference signal is as follows:
Figure BDA0003828765660000031
where f is the observation frequency of the satellite that retransmits the interfering signal, Δ v = v r -v s Is the relative movement between the satellite and the local user terminal, v r Is the speed, v, of the local user terminal s Is the velocity of the satellite, c is the speed of light 3X 10 8 m/s，f 0 Is the carrier frequency of the satellite transmission, the frequency f forms a doppler curve with respect to the time diagram.
If the position of the interference source cannot be determined in step 300, no interference information is formed, and interference source statistics are not taken into account.
The invention adopts the ground receiving station deployed globally, realizes the data receiving of satellites in different places, has higher coverage area and real-time performance and accurate positioning precision, is beneficial to searching of interference sources, thereby reducing the interference of the interference sources on the signals received by the satellites and the ground station and improving the positioning precision and the positioning time efficiency of the position marker in danger.
The stated objects of the invention, as well as other objects not listed here, are met within the scope of the independent claims of the present application. Embodiments of the invention are defined in the independent claims, with specific features being defined in the dependent claims.
Drawings
The technical solution of the present invention is explained in detail below with reference to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of an international search and rescue satellite system;
FIG. 2 is a coding format of 406.0-406.1MHz distress signpost signals;
FIG. 3 is a short message encoding format of a 406MHz distress signpost signal;
FIG. 4 is a long message encoding format of a 406MHz distress signpost signal;
FIG. 5 is a flowchart of a method for identifying and monitoring an interference source of the international search and rescue satellite system according to the present invention;
fig. 6 is a graph of observed frequency versus time for a LEO satellite transmitting an interfering signal.
Detailed Description
The features and effects of the present invention will be described in detail below with reference to the accompanying drawings in conjunction with exemplary embodiments.
Generally, the signal with degraded or damaged reception quality of the radio signal receiving station caused by illegal radio transmission can be referred to as radio interference. The invention mainly aims at 406.0-406.1MHz frequency band interference sources, monitors and positions 406.0-406.1MHz frequency band interference sources all over the world by using a low orbit satellite group and ground receiving stations distributed in 45 countries and regions, and distributes monitored interference source information including interference source transmitting time, transmitting frequency, transmitting coordinate position and the like through a task control center. Thereby identifying, positioning and confirming the 406.0-406.1MHz frequency band interference signals.
The interference source of the invention particularly refers to the interference signal of the 406.0-406.1MHz frequency band. And judging the signals as interference signals as long as the signals which do not meet the requirement of the 406MHz distress signpost.
The identification of the 406.0-406.1MHz frequency band interference signal is realized by judging whether the signal characteristic accords with the distress indication landmark characteristic. The real distress signal and the interference signal can not be distinguished when the satellite receives the signal, because the signal is a 406.0-406.1MHz frequency band signal which is transmitted, the satellite is only responsible for forwarding the radio signal to the ground station, and the ground station is responsible for distinguishing the real distress indication beacon and the interference.
Firstly, the format of the standard code used for the distress signpost code is determined, and as shown in fig. 2, the code format of the 406MHz distress signpost signal is shown. The figure shows two coding formats of message frames of 406MHz distress indication signposts adopting different protocols, the message types of all fields are clear, and in the following steps, the interference signals are judged according to the marks fixed by the bits.
The 406MHz distress indication beacon signal supports two messages with the same frame format but different total bit numbers, wherein the short message is a 112-bit signal, and the long message is 144 bits. FIG. 3 is a short message encoding format; fig. 4 is a long message encoding format.
The bits of the 406MHz distress signpost message frame are divided into five groups:
1. synchronization group: bits 1 to 24 are systematic bits, bits 1 to 15 are bit syncs, and bits 16 to 24 are frame syncs.
PDF-1: bits 25 to 85 are data bits. This set of data bits is called PDF-1 (protected data field), bit 25 defining the message type, "0" for short message format or "1" for long message format.
BCH-1: bits 86 to 106 are BCH error correction codes that can detect and correct errors of up to 3 bits among the bits of PDF-1 and BCH-182.
4. The content of the fourth group depends on the message format.
Short message format: bits 107 through 112 are not protected data bits. FIG. 3 shows a short message encoding format;
long message Format (PDF-2): positions 107 through 132 are data bits protected by a second protected data field. FIG. 3 shows a short message encoding format; fig. 4 is a long message encoding format.
BCH-2: last 12 bits are applicable to only long messages (133 th to 144 th bits), and errors of at most 2 bits among 38 bits of BCH-2 and PDF-2 are detected and corrected.
The emission power output of the 406MHz distress indication position is 35-39dBm, a signal with the duration of 0.5s is sent every 50s, and the signal can be emitted for 24 hours at minimum. The power output rise time should be less than 5ms at the 10% to 90% power point, assuming that the power output rises linearly from zero, it must be zero before 0.6ms begins from the rise time measurement; if not, the maximum acceptable level is-10 dBm. The 406MHz distress index thus determines the output power range.
Referring to fig. 1, the ground receiving station of the international Search and Rescue satellite uses a LEOSAR (Low Earth Orbit Search and Rescue satellite system) system to identify and monitor the interference source. The ground receiving station of the international search and rescue satellite system is divided into a Local user terminal 3 (LUT) and a Mission Control Center 4 (MCC), wherein the LUT is a satellite signal receiving station fixedly distributed in different regions in the world and used for receiving 406.0-406.1MHz signals transmitted by satellites, after the signals are compiled and analyzed for ambiguity, interference source information is screened out, the interference source information is transmitted to a target MCC through the MCC system through a network, an interference source detection result is finally formed, and the monitoring of the interference source in the 406.0-406.1MHz frequency band is completed.
Please refer to fig. 5, which is a flowchart of the interference source identification and monitoring method of the international search and rescue satellite system according to the present invention; the search and rescue satellite system comprises 1-N satellites, 1-N LUTs and MCCs which are located on the ground, and the system receives 406.0-406.1MHz frequency band signals transmitted by the satellites, including real distress signals and interference signals in the frequency band, and firstly distinguishes the interference and the real distress signals. The invention judges the signal which does not meet the requirements of all 406MHz distress indication beacon specifications as the interference signal. Firstly, distinguishing interference signals and real distress signals according to the following steps:
1. step 100, judging the signal emission rule
The 406MHz distress signaling bit is burst every 50s, with each transmission time being about 520ms + -1%. When the 406MHz distress indicator is activated, a CW (consisting of an unmodulated carrier with a transmit frequency measured between the 90% power point and the beginning of modulation) preamble is generated before transmitting the encoded data (message and error signal), the CW carrier lasts about 160ms +1% (between 158.4ms-161.6 ms), then a long message transmits 360ms (144 bits of information), a short message transmits 280ms (112 bits of information), and the transmission bit rate is 400bps. Most of the 406MHz band interference signals are usually longer in duration, and can be distinguished by the signal transmission time. If the signal transmission time is more than 520ms +/-1%, the signal can be judged as an interference signal, and if not, the next step is carried out.
2. Step 200, judging the coding format
The 406MHz distress indication bitmark specifies that the 1 st to 24 th bits are systematic bits, wherein the bit sync of the 1 st to 15 th bits is 111111111111111 (15 bits are 1), and the frame sync of the 15 th to 24 th bits is 000101111 (011010000 under the self-test mode). Only if the bit sync and the frame sync are consistent, the distress beacon signal is identified (i.e. the first 24 bits of the signal are 111111111111111000101111), and the inconsistency is identified as a jamming signal. The bit sync and the frame sync in the self-check mode are identical to 111111111111111111011010000, and otherwise, the bit sync and the frame sync are recognized as an interference signal.
If the first 24 bits of the interference signal are just consistent, the verification needs to be carried out through the 25 th to 36 th bit codes, the 25 th bit of the normal signal identifies the message type (0 is a short message, and 1 is a long message), the 26 th bit of the normal signal identifies the message type (1), and the 26 th bit of the normal signal identifies the country code, and the 25 th to 36 th bits of the normal signal do not completely accord with the above rule and are judged as the interference signal.
If the signal is judged to be normal, the signal is normally processed according to the distress information, and if the signal is judged to be interference information, the signal is distributed to a corresponding task control center for processing.
3. Step 300, determining the Doppler position of the interference signal
The interference source positioning of the invention is to position the interference source by utilizing the interference signal per se, which is called as passive positioning, and the relative speed between the interference source and the satellite is measured and calculated according to the Doppler effect between the satellite and the interference source. The method comprises the steps of combining measurement and calculation data of a plurality of low-orbit ground receiving systems and different satellites to obtain distance differences between an interference source and the satellites, forming two or more hyperboloids by adopting a hyperboloids intersection positioning principle, and forming an intersection point through intersection of the hyperboloids, thereby calculating the position of the interference source and realizing the positioning of the interference source. The interference source position can not be determined only by providing information by a single satellite, and the interference source position can be determined by the aid of a plurality of satellites. Therefore, MCC needs to be communicated, signals detected by a plurality of satellites are adopted to receive and exchange data with a ground receiving station, so that interference source positioning is realized, and monitored interference source information including interference source transmitting time, transmitting frequency, transmitting coordinate position and the like is distributed through the MCC.
The position of the interference source is realized by Doppler processing of the signal by an orbital LEO (Low Earth Orbit Satellite) Satellite, and the LUT can independently process the downlink frequency spectrum of the search and rescue repeater and determine the Doppler curves from the position indicator and the interference source.
As the LEO satellite moves relative to the LUT, a frequency change relative to the LUT results. When a LEO satellite approaches a LUT, the carrier transmitted each time is transmitted at a closer position than the previous time. Therefore, the received wavelength becomes shorter and the frequency increases. Conversely, when the LEO satellite is far from the LUT, each transmitted carrier is transmitted at a location further away than the previous one. Therefore, the received wavelength becomes longer and the frequency is lowered. When the velocity Δ v of the LEO satellite relative to the LUT is much lower than the transmission velocity of the carrier, the observation frequency f of the LEO satellite transmitting the interference signal can be expressed as:
Figure BDA0003828765660000071
wherein Δ v = v r -v s Is the phase between the satellite and the LUTFor movement, v r Is the speed, v, of the LUT s Is the velocity of the satellite, c is the speed of light 3X 10 8 m/s，f 0 Is the carrier frequency of the satellite transmission.
The doppler frequency shift is the frequency difference between the transmitting end and the receiving end:
Δf＝f-f 0
then there are:
Figure BDA0003828765660000072
the relative velocity between the satellite and the interference source can be expressed as:
Figure BDA0003828765660000073
Figure BDA0003828765660000074
is the velocity vector of the satellite or satellites,
Figure BDA0003828765660000075
is a velocity vector of the interference source, therefore
Figure BDA0003828765660000076
Is the relative velocity of the satellite with respect to the source of the interference.
Figure BDA0003828765660000077
Is a normalized vector of interference sources to satellites,
Figure BDA0003828765660000078
is a position vector of the satellite(s),
Figure BDA0003828765660000079
is the position vector of the interference source, and theta is the propagation angle of the interference source to the satellite.
Due to the movement between the interferer and the satellite, the frequency of reception is highest when the satellite initially enters the field of view of one interferer and continues to decrease until the interferer moves out of view. The resulting frequency versus time plot constitutes a doppler curve. The LUT analyzes the doppler curve to determine the point of inflection in the curve (i.e., the point at which the curve changes curvature). If the Doppler curve does not contain an inflection point, the LUT infers that the curve is either forward or backward in time to estimate the inflection point. At the knee point, the doppler shift is zero, since the instantaneous relative velocity Δ ν between the interferer and the satellite is now zero, which is the closest time instant (TCA) between the interferer and the satellite. The LUT may also determine the slope of the Doppler curve at TCA, which is critical to determining the geographic location of the source.
The plot of frequency versus time, see fig. 6, contains the inflection point as the satellite moves toward the interferer, the frequency going from a maximum at time T1, through 0 at time T2, and becoming a minimum at time T3. This is the doppler shift effect.
The time when the satellite and the interference source are closest is calculated by determining the inflection point of the Doppler curve, and the satellite, the position of the interference source and the geocenter form a triangle by combining the position of the satellite. And applying the trigonometric function to obtain a distance equation between the satellite and the interference source. Combining the measuring and calculating data of a plurality of satellites and the LUT station, a plurality of ranging equations can be formed for the same interference source, and the position of the interference source can be calculated by solving the polynomial equation.
Step 400, confirming the position and frequency of the interference source:
the position of the interference source is confirmed by the position information of the 406.0-406.1MHz frequency band interference source, 40 global task control centers are communicated through an FTP (File Transfer Protocol) network, and data receiving and exchanging are carried out by adopting signals detected by a plurality of satellites and a ground receiving station, so that the position confirmation of the interference source is realized. The same interference source can continuously transmit, and the interference sources at the same position are identified as the same interference source within 72 hours, and detection counting is carried out; once the location changes or is not monitored within 72 hours, another interference source is identified and the detection count is repeated (fig. 5 interference detection flow chart).
The MCC screens the interference sources in the service area according to the interference source monitoring result, distributes information such as the emission time, the emission frequency, the emission coordinate position and the like of the interference sources to the MCC in the service area, and the MCC staff in the local area submits interference position data to a radio management department for troubleshooting.
The interference monitoring technology has the advantages that the global ground receiving station is adopted, the satellite receiving data of different places are realized, the coverage area and the real-time performance are high, the positioning precision is accurate, the searching of an interference source is facilitated, the interference of the interference source to the satellite and the ground station receiving signals is reduced, and the positioning precision and the positioning time efficiency of the distress indication beacon are improved.
While the invention has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the disclosed device structure and its method of manufacture will include all embodiments falling within the scope of the present invention.

Claims (6)

1. An interference source identification and monitoring method of an international search and rescue satellite system adopts a low-orbit search and rescue satellite system, the system comprises at least one satellite and at least one ground receiving station, wherein each ground receiving station comprises a local user terminal and a task control center, the ground receiving station receives a radio signal which is sent by the satellite and contains a normal signal and an interference signal, and then the interference source identification and monitoring are carried out according to the following steps:
step 100, judging that the signal transmission time is more than 520ms +/-1% as an interference signal, otherwise, carrying out the next step;
step 200, further judging the coding format:
firstly, judging that the bit synchronization identification of the 1 st to 15 th bits of the signal and the frame synchronization identification of the 16 th to 24 th bits of the signal are not synchronous and consistent and can be judged as an interference signal;
secondly, the 25 th bit of the normal signal identifies the message type, the 26 th bit protocol identification is 1, the 27 th to 36 th bits are country codes, and if the 25 th to 36 th bits do not completely accord with the rules, the normal signal is judged to be an interference signal;
step 300, if judging as an interference signal, determining the Doppler position of the interference signal and sending the Doppler position to a certain task control center:
positioning by adopting a plurality of satellites and a plurality of ground receiving stations to determine the position of an interference source; and distributing the monitored interference source information including the transmission time, the transmission frequency and the transmission coordinate position of the interference source through the task control center.
2. The method of claim 1, further comprising: further comprising step 400 of confirming the positioning information of the interference source:
a plurality of global 40 task control centers are communicated through a file transfer protocol network, and signals detected by a plurality of satellites and a low-orbit ground receiving station are adopted for data receiving and exchanging, so that the position confirmation of an interference source is realized; if the interference sources at the same position are monitored within 72 hours, the interference sources can be identified as the same interference source, and detection counting is carried out; once the position is changed or not monitored within 72 hours, another interference source is identified and the detection counting is performed again.
3. The method of claim 1, further comprising: the bit synchronization mark of the 1 st to 15 th bits of the signal in the step 200 is consistent with the bit synchronization mark of the 16 th to 24 th bits of the signal, that is, the first 24 bits of the signal are 111111111111000101111; or 111111111111111111011010000 in self-test mode.
4. The method of claim 1, further comprising: the main formula adopted in the step 300 for determining the doppler position of the interference signal is as follows:
Figure FDA0003828765650000021
where f is the observation frequency of the satellite transmitting the interfering signal, Δ v = v r -v s Is the relative movement between the satellite and the local user terminal, v r Is the speed, v, of the local user terminal s Is the velocity of the satellite, c is the speed of light 3X 10 8 m/s，f 0 Is the carrier frequency of the satellite transmission, the frequency f forms a doppler curve with respect to the time diagram.
5. The method of claim 1, further comprising: if the interference source location cannot be determined in step 300, it is determined to be no location interference information.
6. The method of claim 1, further comprising: bit 25 in step 200 defines the message type, "0" for short message format or "1" for long message format.
CN202211067019.9A 2022-09-01 2022-09-01 Interference source identification and monitoring method of international search and rescue satellite system Pending CN115421166A (en)

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