CN115032586A - Communication satellite interference source positioning system based on satellite communication station - Google Patents

Abstract

The invention discloses a communication satellite interference source positioning system based on a satellite communication station. The fixed central station adopts the double-star or three-star positioning mode to complete the initial positioning of the interference source; the vehicle-mounted station performs the mobile positioning task issued by the central station to complete the ground interference source investigation; the UAV station is used as a positioning capability enhancement system to carry out the interference source. Spectrum data forensics; signal monitoring and interference source positioning platform, as the core management system of the entire interference source positioning, completes the operation control of system equipment, and adopts the working method of "mission planning-task execution-result feedback" to meet the user's business needs. The realization of the invention greatly improves the reliability and accuracy of the positioning of the interference source of communication satellites, provides a feasible solution for the radio management committee to comprehensively monitor the spectrum of all communication satellites, especially the positioning of the interference source, and further improves the satellite spectrum resources. Ability to manage and secure communications.

Description

Communication Satellite Interference Source Locating System Based on Satellite Communication Station

technical field

The invention belongs to the application field of satellite communication, and relates to a system solution for locating signals of ground interference sources of communication satellites.

Background technique

With the rapid development of electronic informatization and the widespread popularization of wireless communication technology, satellite communication technology has become an important development direction, and at the same time it has promoted the continuous changes of modern military and social production. In modern military warfare, the multi-dimensional integration of sea, land, air and space requires the establishment of a multi-level, high-complexity, large-capacity integrated integrated communication system. Satellite communication plays an important role in coordination, command, communication and control. The initiative of information electronic warfare will directly determine the initiative of the frontal battlefield, which promotes the continuous improvement and improvement of the reconnaissance and anti-reconnaissance capabilities of the military satellite communication system. The satellite communication system intercepts the enemy's intentional or unintentional electronic radiation, and accurately locates the radiation signal source, which will provide a strong basis for the acquisition of dynamic battlefield information and provide strong support for the final strategy and tactics.

The passive passive positioning system uses satellites as a platform for positioning through the cooperation of satellites and ground receiving stations, and uses the basic information of the interference source target location and the positioning surface determined by multiple positioning parameters to accurately locate the signal interference source. . This passive satellite positioning method has low requirements for the geographical location of the interference source, small environmental restrictions, wide coverage and high concealment, and can quickly and accurately locate the position of the interference source target. Practical significance and important role. The passive positioning system of satellites can be divided into single-line positioning system, dual-satellite positioning system and multi-satellite positioning system of satellite constellation according to the number of satellites involved in positioning. Among them, the single-satellite positioning system has short positioning time, simple implementation and low system operation cost; the dual-satellite positioning system has short positioning time, low system operation cost, high positioning accuracy and mature method technology; the multi-satellite positioning system of the satellite constellation covers The area is extensive, the positioning accuracy is high, and the system implementation is relatively complex. The above methods only rely on satellites and fixed ground receiving stations, have certain requirements on terrain conditions and environment, and have certain limitations in use scenarios.

Therefore, in view of the limitations of the traditional satellite interference source positioning method, the present invention proposes a communication satellite interference source positioning system solution. At the same time, the integrated unified management software is deployed in the signal monitoring and interference source positioning platform to carry out unified command and dispatch of the whole system, make up and optimize the traditional interference source positioning solution, and overcome the complex environment such as remote suburbs, mountains and high-rise buildings. The positioning difficulties brought about, thus greatly expanding the application scope of the interference source positioning, improving the positioning accuracy and timeliness, and further enhancing the anti-interception and anti-jamming capabilities of the satellite communication system.

SUMMARY OF THE INVENTION

The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, provide a communication satellite interference source positioning system, optimize and perfect the traditional interference source positioning solution method, greatly improve the system positioning accuracy, and increase the system mobility and flexibility sex.

The technical solution of the present invention is: a communication satellite interference source positioning system based on a satellite communication station, including a satellite communication station and a signal monitoring and interference source positioning platform; the satellite communication station includes a fixed central station, a vehicle-mounted station and a wireless man-machine station;

The signal monitoring and interference source positioning platform generates a mission plan according to the user's business needs, and sends scheduling instructions to the fixed central station, motor vehicle station and/or UAV station in the satellite communication station according to the mission plan;

The fixed central station responds to the scheduling instruction scheduling, is used to complete the initial positioning of the interference source, and sends the initial positioning information to the signal monitoring and interference source positioning platform;

The motor vehicle on-board station responds to the scheduling instruction scheduling, is used for performing mobile positioning tasks and completes the investigation of ground interference sources, and sends the investigation results to the signal monitoring and interference source positioning platform;

The unmanned aerial vehicle station responds to the scheduling instruction scheduling, is used for spectrum data forensics for the designated interference source, and sends the acquired spectrum data to the signal monitoring and interference source positioning platform;

The signal monitoring and interference source positioning platform adjusts the mission plan in real time according to the information fed back by the satellite communication station, sends scheduling instructions to the corresponding satellite communication station according to the new mission plan, and finally locates the interference source according to the information fed back by the satellite communication station.

Preferably, the fixed central station adopts a synchronous double-star or three-star positioning mode to perform preliminary positioning of the interference source.

Preferably, the target signal is a modulated signal transmitted by a fixed central station, and two time difference (TDOA) position lines or two frequency difference (TDOA) position lines in the dual-satellite positioning mode are directly used to perform a rendezvous positioning process; for some special signals Or application scenarios, including the positioning of moving target signals or unmodulated signals (CW signals and CW frequency sweep signals) emitted by fixed targets, it is necessary to use the Samsung positioning mode for positioning, and enhance the detection of neighboring satellites through signal cancellation and signal preprocessing. Adaptability to signal conditions and target signal conditions.

Preferably, the three-star positioning mode includes three target satellites, one of which is used as the main satellite, and the other two are compatible with the main satellite as adjacent satellites; one of the fixed central stations is selected as a reference station, and the rest are used as positioning stations, and each positioning station corresponds to Collect the signal of a target satellite;

According to the mission plan, schedule the positioning antenna of the positioning station to point to the main and adjacent satellites, configure the receiving link equipment and the L-band switch matrix;

Control the reference station to point to the target satellite and transmit the reference signal at the designated frequency;

According to the task loading work configuration parameters, the target and reference signals are collected synchronously, the sampling data of the main adjacent satellite signal is obtained, the sampled data is subjected to mutual fuzzy correlation processing, and the time difference of arrival TDOA and the main adjacent star generated by the different paths of the signal passing through the main adjacent satellite are extracted. The arrival frequency difference FDOA caused by the Doppler frequency shift caused by the different relative velocities of the on-orbit perturbation completes the positioning parameter estimation;

Using the satellite ephemeris data to solve the positioning equation, the time difference position line and the frequency difference position line are obtained, and the best positioning point is obtained by the intersection of the two lines.

Preferably, the compatibility of adjacent satellites includes forwarding compatibility, coverage compatibility, reference station signal, ephemeris calibration signal and selected parameters for rendezvous positioning.

Preferably, the adjacent star is selected in the following manner:

First, the adjacent satellite should have the beam coverage, polarization, frequency band and transponder available in combination with the main satellite, and have the available initial ephemeris to meet the basic conditions for locating the target signal;

Secondly, consider the influence of the satellite distance on the processing gain to avoid exceeding the processing capability of the signal monitoring and interference source location platform;

Finally, analyze the error situation of the combination of the selected neighbor star and the main star, and avoid the positioning blind moment when the angle between the positioning line is zero.

Preferably, the vehicle station is equipped with a satellite downlink signal monitoring antenna, the antenna adopts a vehicle-mounted antenna, the main surface of the antenna is a standard paraboloid, the antenna structure is a folding method, the antenna panel is folded during transportation, and the antenna panel is unfolded during operation. Accurate positioning by positioning pins; when working, the vehicle is stopped and leveled, and after installing the corresponding frequency band feed, adjust the antenna to aim at the target to start work.

Preferably, the UAV station adopts a multi-rotor unmanned aerial vehicle as a carrying platform, and uses the floating signal monitoring technology to monitor the uplink signal of the transmitting earth station and take photos of the interference source and target site for evidence collection.

The beneficial effects of the present invention compared with the prior art are:

The invention deploys unified management software in the signal monitoring and interference source positioning platform to carry out unified management and scheduling of the whole system, adopts Samsung interference source positioning to improve positioning accuracy, uses positioning algorithm for calculation, and introduces motor vehicle station and unmanned aerial vehicle at the same time. The stations are respectively used for ground investigation of interference sources, target photography and spectrum forensics, and finally accurately locate the interference source of the ground station antenna.

Compared with the existing interference source positioning method, the present invention further improves the accuracy and reliability of the positioning target, and at the same time overcomes the positioning difficulties caused by complex environments such as remote suburbs, high mountains, high buildings, etc., thereby greatly expanding the interference source positioning method. The scope of application improves the positioning accuracy and timeliness, and enhances the anti-interception and anti-jamming capabilities of the satellite communication system.

Considering the ubiquity and easy promotion of the interference source positioning method, the unified management software is deployed in the signal monitoring and interference source positioning platform to realize the unified management and scheduling of the interference source positioning system, and the motor vehicle station and the UAV station are introduced to achieve accurate The positioning, method establishment and optimization are mainly reflected in the following aspects:

(1) Based on the diversity of satellite spectrum, the system deploys a variety of satellite communication ground station types, including fixed central stations in C, Ku, and Ka frequency bands, vehicle-mounted stations and UAV stations;

(2) In order to improve the collaborative working ability of the system, an integrated unified management software is deployed in the signal monitoring and interference source positioning platform to conduct unified command and dispatch of system resources;

(3) Considering the complexity and harshness of the environment where the antenna of the interference source ground station is located, a vehicle-mounted station and an unmanned aerial vehicle station are introduced, which can maneuver the fixed central station to conduct ground investigation of the interference source and take photos of the antenna of the target ground station. And spectrum data forensics, greatly improving the accuracy and timeliness of interference source location.

Description of drawings

Fig. 1 is a composition diagram of a communication satellite interference source positioning system based on a satellite communication station;

Fig. 2 is a working flow chart of a communication satellite interference source positioning system based on a satellite communication station;

Figure 3 is a schematic diagram of a dual-star positioning mode;

Figure 4 is a simulation diagram of a double-star positioning cross line;

Figure 5 is a schematic diagram of Samsung positioning mode;

Figure 6 is a 3-D CAF correlation output diagram;

Fig. 7 is a schematic diagram of orbit determination of spontaneous and self-received time difference;

Fig. 8 is a schematic diagram of the calculation principle of the isochronous position line;

Fig. 9 is a schematic diagram of the TDOA position line;

Figure 10 is a schematic diagram of the Samsung dual frequency difference rendezvous positioning principle;

Fig. 11 is a schematic diagram of the position line of TDOA/FDOA intersection positioning;

FIG. 12 is a schematic diagram of a position line for TDOA/TDOA intersection positioning;

Figure 13 shows the simulation results of the radiation characteristics of the 4.8-meter-diameter antenna corresponding to different frequencies;

Fig. 14 is the main workflow of positioning processing;

FIG. 15 is a process flow related to reference signal CAF;

Figure 16 is the workflow of double star positioning;

Figure 17 shows the Samsung positioning workflow;

Fig. 18 is the parameter setting process of the fixed central station positioning system of the satellite interference source;

Figure 19 shows signal acquisition and storage;

Figure 20 is a simple flow of PODS track determination;

Fig. 21 shows correlation processing and parameter estimation;

Fig. 22 is based on the communication satellite interference source positioning workflow;

FIG. 23 is a display diagram of the positioning result.

Detailed ways

The present invention will be further elaborated below in conjunction with the examples.

With the rapid development of electronic informatization and the widespread popularization of wireless communication technology, satellite communication technology has become an important development direction. In modern military warfare, the multi-dimensional integration of sea, land, air and space requires the establishment of a multi-level, high-complexity, large-capacity integrated integrated communication system. Satellite communication plays an important role in coordination, command, communication and control. The initiative of information electronic warfare will directly determine the initiative of the frontal battlefield, which promotes the continuous improvement and improvement of the reconnaissance and anti-reconnaissance capabilities of the military satellite communication system. The satellite communication system intercepts the enemy's intentional or unintentional electronic radiation, and accurately locates the radiation signal source, which will provide a strong basis for the acquisition of dynamic battlefield information and provide strong support for the final strategy and tactics. In this context, the present invention proposes a communication satellite interference source positioning system based on a satellite communication station, which adopts a three-star positioning mode of high-precision positioning, and is supplemented by vehicle-mounted stations and unmanned aerial vehicle stations to obtain evidence to complete accurate detection in complex environments. position. Hereinafter, the present invention will be described in detail based on the drawings.

As shown in Figures 1 and 2, it is a composition diagram of a communication satellite interference source positioning system based on a satellite communication station, including a signal monitoring and interference source positioning platform and a satellite communication station. station and drone station.

(1) The signal monitoring and interference source positioning platform is the core management system of the interference source positioning system. It conducts unified management and scheduling of the fixed central station, the vehicle-mounted station and the UAV station, and completes various aspects of satellite monitoring and interference source positioning. Task and operation control, including system management, task management, equipment status and running status monitoring, database management, etc. The signal monitoring and interference source positioning platform can also be interconnected with the data center (headquarters) through the ground network to realize remote operation and control of the system. The platform adopts the working method of "task planning-task execution-result feedback" to complete the user's business needs. The realization process is as follows:

a) According to business requirements, the signal monitoring and interference source positioning platform accesses the satellite information database, sets monitoring equipment and measurement parameters, and formulates and generates mission plans;

b) When executing the mission plan, the platform automatically sets the parameters of the controlled equipment or system and configures the system related to the mission;

c) After the task starts, automatically guide the antenna to perform satellite alignment and tracking according to the satellite orbit position information in the satellite parameter database;

d) During the task execution process, the equipment running status and task completion status are monitored in real time and displayed in a centralized manner;

e) After the task is completed, the corresponding task execution report is generated through the unified management software deployed in the platform, and the monitoring and positioning results are stored in the database for preservation.

(2) The signal monitoring and interference source positioning platform is to perform all-round satellite spectrum monitoring and interference source positioning for the satellite resources in the user-specified area, supplemented by the vehicle-mounted station and the UAV station to accurately locate the interference source and take photos for evidence collection. Allow users to fully autonomously control and supervise their satellite spectrum resources.

Specifically, the satellite fixed central station uses the dual-star or three-star positioning mode to perform satellite spectrum monitoring and preliminary positioning of interference sources; the vehicle-mounted station conducts ground interference source investigation and assists the fixed central station to complete satellite spectrum monitoring and interference source positioning; UAVs As a supplementary system, the station is used for spectrum monitoring and aerial photography of the uplink of the target ground station, and forensics of the interference source.

(3) Preliminary positioning of the interference source by the fixed central station

The fixed central station adopts the synchronous double-star or three-star positioning mode to initially locate the interference source.

1) Double star positioning mode

The two satellites used for dual-satellite positioning are usually two synchronous satellites that are close to each other. The satellite that is disturbed is the main satellite, and the satellite that is used for auxiliary positioning in the adjacent position is called the adjacent satellite. Due to the antenna characteristics of the transmitting station, the main lobe of its beam is usually aimed at the main star, while a side lobe of the beam is directed towards the adjacent star. The two satellites down-convert the received uplink signals and forward them to the ground, and the receiving stations in the satellite coverage area can receive these forwarded signals, as shown in Figure 3.

The homologous signals from the main lobe and side lobes of the antenna of the transmitting station only differ in power level, and the propagation paths of the signals are different after being transmitted by two different satellites, so a different time difference (DTO—differential timeoffset) is generated, and the time difference can be Using the homologous signal to perform correlation comparison estimation, it corresponds to the distance difference of the propagation path. Due to the different operating speeds of the synchronous satellites, a frequency difference (DFO—differential frequency offset) is formed.

According to the definition of solid geometry, a point whose distance difference to two fixed points in space is a constant constitutes a hyperboloid. Therefore, for the determined positions of the two satellites, the trajectory determined by a certain DTO value is a unilateral hyperboloid (using the positive and negative DTO to exclude the other hyperboloid), which can intersect with the earth's spherical surface to form a curve. The curve is usually symmetrically distributed on both sides of the earth, and the part located in the satellite coverage area is called the LOP-line of position, and the uplink signal transmitting station on the ground is located on this hyperbola. Since the time difference is mainly caused by the distance difference between the transmitting station and the two satellites, it is generally distributed along the longitude direction perpendicular to the satellite connection, as shown in Figure 4. In order to get the correct DTO value, it is necessary to know the geometric relationship between the satellites and the propagation delay of the signal between the satellite and the receiving station.

A single DTO value can only give a position line, and the position of the transmitting station cannot be determined yet. Other parameters must be used. The Doppler frequency difference caused by satellite perturbation is used in the dual-satellite positioning.

2) Samsung positioning mode

Compared with double-star positioning, three-star positioning needs to use one more neighboring star. The schematic diagram of positioning principle is shown in Figure 5.

3) The basic working principle of the communication satellite interference source positioning system

The system equipment receives the positioning task from the carrier monitoring or application system from the signal monitoring and interference source positioning platform, or directly initiates the positioning task by the operator in the unified management software interface in the platform.

The unified management software decomposes the mission parameters, schedules the positioning station antenna to point to the main satellite and the adjacent satellite, configures the receiving link equipment and L-band switch matrix, and connects the main adjacent satellite link required by the mission to the multi-channel signal configured by the positioning station. Acquisition and processing equipment/boards. The unified management software controls the reference station to point to the target satellite and transmits the reference signal at the designated frequency.

The signal monitoring and interference source location platform loads the work configuration parameters according to the task, synchronously collects the target and reference signals, obtains the sampling data of the main adjacent satellite signal, sends the sampled data to the correlator for mutual fuzzy correlation processing, and extracts the signal through the main adjacent satellite path. The time difference of arrival TDOA generated by the different generation and the frequency of arrival FDOA caused by the Doppler frequency shift caused by the relative velocity of the main neighbor satellite on-orbit perturbation are used to complete the positioning parameter estimation.

After the positioning parameter estimation is completed, the system will use the satellite ephemeris data to solve the positioning equation to obtain the time difference position line and the frequency difference position line, and the best positioning point is obtained by the intersection of the two lines. In the positioning process, the processing of the reference station signal can also be used to calibrate the positioning error, and the combination of different position lines can be used to adapt to special signal types. Signal cancellation and signal preprocessing are used to enhance the signal conditions of neighboring satellites and target signals. The ability to adapt to conditions improves the success rate and positioning accuracy of positioning.

a) Positioning parameter estimation

The satellite ground station transmits the signal s1(t) to the target satellite (main star) through the main lobe of the antenna, but due to the radiation characteristics of the antenna, the antenna also radiates a signal s2(t) with a certain energy to the space through its side lobes, s1( t) and s2(t) are homologous, and s2(t) can be received and retransmitted by compatible satellites in adjacent orbits.

Signal mutual ambiguous correlation is the core of signal processing of positioning equipment. In order to obtain DTO and DFO of two signals s1(t) and s2(t) at the same time, the cross ambiguity function (Cross Ambiguity Function, CAF) is used to realize the mathematical expression as follows shown:

Among them, τ is the time difference; f is the frequency difference; T is the correlation accumulation time.

When τ=DTO, f=DFO, the CAF outputs the maximum value, which means that the unbiased estimation of DTO and DFO has been completed. Since the main and adjacent satellite signals are homologous, they have correlation, but the correlation to other signals or noise is very weak, Therefore, as long as the correlator accumulation time T is long enough, the correlation of the main neighbor signal can be achieved.

Convert the above continuous domain CAF function to discrete domain (sampled signal), t=nT _s , f=kf _s /N, T _s is the sampling period, f _s =1/T _s is the sampling frequency, and n is each sampling point , N is the total number of sampling points, and the CAF expression for discrete signals is obtained:

At this time, τ=DTO, and k/N=DFO. Figure 6 shows the CAF correlation output.

b) Reference station ephemeris measurement

At present, the orbit measurement of geostationary communication satellites in China is mostly realized by single-station sound and distance measurement combined with angle measurement. With the advancement of BD-2 system engineering development, some new methods have been introduced one after another. At present, there have been engineering experiments in China that use one primary station and three secondary stations to perform orbit measurement in the method of sending and receiving at the same time. The lengthened pseudo-code ranging is used. In addition to the time difference, the satellite frequency difference should also be measured, the frequency band The C and Ku frequency bands are used, and the time synchronization adopts the rubidium clock and the two-way common view of the satellite. According to the experimenter, this method is currently the method with the highest orbit measurement accuracy for geostationary communication satellites in China. Its ranging accuracy can reach centimeter level, and its orbit determination accuracy can reach meter level.

Taking the system of measuring distance difference as an example, four distances can be obtained by measuring the time difference of four signals by means of four stations spontaneously sending and receiving. The first station is called the primary station, and the other receiving stations are called secondary stations.

As shown in Figure 7, it is assumed that A, B, C, and D are four ground stations, of which A is the master station, which can send signals to the target. The coordinates of the four stations are known as (x _i , y _i , z _i ), i=1, 2, 3, 4, and the satellite S (x, y, z) is the satellite to be orbited, then the geocentric coordinates In the system, the slant distance from the satellite to the ground station is:

In the self-transmitting and self-receiving mode, each station independently transmits and receives signals to the satellite at the same time, and extracts the time difference to obtain the following measurement equation (in the ground-fixed coordinate system):

c(τ _i -delay)=2d _i =2||rr _si ||=H(r)

Among them, c is the speed of light, τ _i is the time difference measured by the i-th station, delay is the satellite transponder delay, d _i is the distance from the station to the satellite, r is the position of the satellite in the ground-fixed coordinate system, r _si is the position of the station in the ground-fixed coordinate system.

Self-transmitting and self-receiving requires each station to have signal transmission capability, and does not require high inter-station synchronization. After each station extracts the time difference, the signal is preprocessed at each sub-station, outliers are removed, and the ground station equipment delay is removed. Correct the influence of atmospheric refraction, extract the smoothed data according to the regular time, and then transmit it to the central station; then, do the initial orbit determination calculation, and then perform the orbit differential improvement to obtain the ephemeris of the satellite and the estimated time delay of the satellite transponder. The calculation of the partial derivative of the observation equation involved in orbit determination is as follows:

First calculate the partial derivative with respect to the satellite state in the ground-fixed coordinate system:

Then convert the partial derivative in the ground-fixed coordinate system to the J2000.0 inertial coordinate system:

4) Positioning solution

a) isochronous position line

As shown in Figure 8, TDOA=ime(T→M→R)-Time(T→m→R),

Assuming that the signal propagates at the speed of light c in free space,

Time(T→M→R)=TM/c+MR/c,

Time(T→m→R)=Tm/c+mR/c,

TDOA=(TM–Tm)/c+(MR–mR)/c,

The position of the monitoring station receiver R is known. If the positions of the main star M and the adjacent star m are accurately known at this time, (MR–mR)/c in the above formula can be calculated by using the positions of the satellite and the receiving station. . Therefore, the equation of time difference (TDOA=constant) can be expressed as:

TM-Tm=D=c×TDOA-(MR-mR).

In engineering, the solution of the isochronous position line can be realized by the search method, which can be carried out according to the following process: first, use CAF to estimate the TDOA parameter; second, calculate D; third, search on the earth surface according to TM-Tm=D A set of position points T is obtained. Fourth, the iso-TDOA is obtained by connecting the line.

The positioning significance of iso-TDOA iso-time difference position line: any position point on the line can satisfy the arrival time difference TDOA obtained by the CAF algorithm, that is, the target can be located at any position of the iso-TDOA position line. Obviously, we can obtain another set of CAF estimation parameters TDOA2 through another adjacent star, and use the same process to obtain the iso-TDOA2, which is the basic principle of Samsung dual-time-lapse rendezvous positioning. Figure 9 is a schematic diagram of the TDOA position line. For a synchronous orbit communication satellite, the typical TDOA position line is north-south. When the orbital distance of the main satellite or the adjacent satellite is relatively close and the inclination angle is large, the trend of the TDOA position line at different times will occur. changes, with the effect of "spinning" over time.

b) Equal frequency difference position line

The satellite is perturbed in orbit, and there is a radial velocity relative to the target, so the signal received by the receiving station has a Doppler frequency shift. Due to the different perturbation speeds of the main neighbor satellite relative to the target, the arrival frequency difference FDOA will be generated when the ground receiving station receives the target signal.

For the main star ascending:

f_M-out＝f_M-up-LO_M；For the main star descending:

f _M-out = f _M-up -LO _M ;

For neighboring stars ascending:

f_m-out＝f_m-up-LO_m；For neighbors descending:

fm _-out =fm _{-up- LOm} ;

Definition: FDOA=f _M-down- f _m-down ; ΔLo=LO _M -LO _m ;

The perturbation speed of synchronous orbit satellites is much less than the speed of light. The first two items in the above formula can be expressed as:

It can be expressed as the following formula:

We precisely know the satellite's position, velocity and local oscillator Lo, the above equation can be converted into the following equation:

In engineering, the solution of the isochronous position line can also be realized by the search method, which can be carried out according to the following process: first, use CAF to estimate the FDOA parameters; second, calculate D'; third, search on the surface of the earth according to D' to obtain A group of position points T, the fourth, connect the line to obtain the iso-FDOA of the equal frequency difference position line.

The positioning meaning of iso-FDOA equal frequency difference position line: any position point on the line can satisfy the arrival frequency difference FDOA obtained by the CAF algorithm, that is, the target can be located at any position of the iso-FDOA of the equal frequency difference position line. Obviously, we can obtain another set of CAF estimation parameters FDOA2 through another neighboring star, and use the same process to obtain the equal frequency difference position line iso-FDOA2, which is the basic principle of Samsung dual frequency difference intersection positioning, as shown in the figure 10 shown.

In general, the target signal is the modulated signal transmitted by the fixed station, and two time difference (TDOA) position lines or two frequency difference (TDOA) position lines in the dual-satellite positioning mode can be directly used for a rendezvous positioning process, which is also the most commonly used at present. rendezvous positioning method. For some special signals or application scenarios, such as the positioning of moving target signals or unmodulated signals (CW signals and CW frequency sweep signals) emitted by fixed targets, the Samsung positioning mode needs to be used for positioning. The ability to adapt to neighboring satellite signal conditions and target signal conditions is enhanced through signal cancellation and signal preprocessing. The positioning of the special signal generally adopts the three-star positioning mode, and locates the target signal through the two sets of TDOA and FDOA position lines obtained by the main satellite and two compatible adjacent satellites. The moving target signal has no frequency difference, and can only be positioned by the double time difference position line; the CW signal and the CW sweep frequency signal have no time difference, and can only be positioned by the double frequency difference position line. Because the signal sent by the positioning station (fixed central station) to the neighboring satellite is relatively weaker than that of the main satellite, and there is a certain frequency offset due to factors such as different local oscillator frequencies on the satellite, positioning processing needs to be deployed in the positioning station. The software performs signal cancellation and signal preprocessing to eliminate signal errors and enhance the ability to adapt to neighboring satellite signal conditions and target signal conditions.

c) Double star rendezvous positioning

Dual-satellite positioning is used to locate the target signal through the TDOA and FDOA position lines obtained by the main star and a compatible adjacent star, or under some special signal conditions and application scenarios, using multiple TDOA and FDOA position line pairs obtained by time-sharing The target signal is positioned, and the rendezvous methods are as follows:

Real-time TDOA/FDOA intersection positioning;

Time-sharing TDOA/TDOA rendezvous positioning;

Time-sharing FDOA/FDOA rendezvous positioning.

Figure 11 is a schematic diagram of the location line for TDOA/FDOA intersection positioning. The typical TDOA location line is mostly north-south, while the FDOA location line is mostly east-west.

d) Samsung Rendezvous Positioning

Samsung positioning locates the target signal through two sets of TDOA and FDOA position lines obtained by the main star and two compatible adjacent stars. The rendezvous methods are as follows:

Real-time TDOA/TDOA rendezvous positioning, which can be used to locate moving targets and fixed ground targets;

Real-time FDOA/FDOA intersection location, which can be used for location of CW signal and CW frequency sweep signal.

Figure 12 is a schematic diagram of the position line for TDOA/TDOA intersection positioning. Since typical TDOA position lines tend to run north-south, the intersection angle of the position lines in the Samsung dual-time-difference intersection scheme is relatively small.

e) Targeting conditions

Having a neighboring star that is compatible with the main star is a necessary condition for binary and triple positioning. Double positioning requires at least one neighboring star, while triple positioning requires two neighboring stars. The compatibility of neighboring stars is embodied in the following aspects:

■Forward compatible

The adjacent satellite transponder is required to adopt a transparent forwarding design; the uplink receiving frequency of the repeater (ground uplink) should be compatible with the main satellite, that is, the adjacent satellite transponder must be able to receive and forward the target and reference signals in its frequency band and frequency design. The downlink transmission frequency of the repeater can be other frequency bands.

■ Overlay Compatible

The satellite transponder corresponds to the corresponding beam, and the coverage compatibility requires that the uplink beam coverage of the adjacent satellite must have sufficient intersection. Only the position of the target and the reference signal is located in the intersection of the main satellite and the adjacent satellite's uplink beam, the adjacent satellite can realize the forwarding of the signal. , the area other than the intersection may cause the signal-to-noise ratio of the adjacent satellite signal to be too low due to low reception G/T and other reasons, resulting in difficulty or failure of signal correlation.

■Reference station signal

Dual-satellite positioning requires at least one reference signal with a known location. In terms of forwarding, the reference signal is required to have the same forwarding characteristics as the target signal, and usually the same set of receivers and local oscillators must be used. The reference signal can be selected from the communication service signal of the known position on the main adjacent satellite, or autonomously transmitted by building a reference station.

■Ephemeris calibration signal

When the satellite ephemeris error is large, such as the public TLE ephemeris, in order to obtain high-precision positioning results, a larger number of reference signals must be used to calibrate or improve the ephemeris accuracy.

■Select reasonable parameters for intersection positioning

There are positioning blind times and blind spots in the dual-satellite and three-star positioning technologies. For example, the dual-satellite positioning application usually has two time periods when the FDOA sensitivity is too low in one orbital period (about 24 hours). Usually larger. When the target is located in a low-latitude area, the angle between the double-time-difference position line is too small, and the positioning error will increase significantly when the target is located in a low-latitude area, which is called the Samsung positioning blind spot. At the same time, different target and signal type positioning applications also have specific technical adaptability requirements. For example, the TDOA resolution of narrowband or CW signals is reduced or invalid. In this case, the FDOA/FDOA intersection method should be considered for positioning; moving target signals due to FDOA failure, At this time, the TDOA/TDOA rendezvous mode should be considered for positioning.

f) Feasibility of positioning parameter estimation

The signal retransmitted by the adjacent satellite is the signal radiated by the far-angle side lobe of the target antenna. Compared with the signal of the main star, the signal-to-noise ratio of the adjacent satellite signal is very low. The main lobe and side lobe gains of the antenna radiation characteristics are as follows:

Figure 13 shows the simulation results of the radiation characteristics of the 4.8-meter-aperture antenna corresponding to different frequencies. The gain of the 40° far-angle side lobe in the C-band is 70dB weaker than the main lobe, and the gain of the Ku-band 20° far-angle side lobe is 70dB weaker than the main lobe. It can be seen that If the adjacent satellite has the same forwarding and coverage characteristics as the main star, when the signal-to-noise ratio of the main star is 10dB, the signal-to-noise ratio on the adjacent satellite can reach -60dB. At this time, the CAF has a processing gain of 80dB theoretically.

It can be seen that the signal of neighboring stars is weak in the positioning scene, but it is possible to finally realize the positioning only if the relevant parameters of the positioning signal can be estimated by CAF to realize the correlation detection of the signal of the main neighboring star. The relationship between the signal correlation and the signal-to-noise ratios γ1 and γ2 of the main neighbor satellite signal can be expressed as follows:

In the above formula, γ is the input signal-to-noise ratio of the correlator, and the peak output threshold of the effective correlation detection of the γ1 correlator is 20dB.

5) Double star/Samsung positioning workflow and steps

The main work flow of positioning processing of the satellite interference source positioning system and the work flow of reference signal CAF related processing are shown in Figures 14 and 15 respectively. Figures 16 and 17 show the specific workflow of the signal monitoring and interference source positioning platform for double-star positioning and three-star positioning.

The specific workflow has five steps:

1) Preparation for positioning and determination of target signal

After accepting the positioning task for a certain signal, the system needs to carry out the necessary preparations, which are mainly to prepare the support conditions such as satellites and ground stations used by the system.

Since the positioning of the primary star is directly determined by the positioning task, the selection of the neighboring star is mainly considered. The selection of adjacent stars needs to comprehensively consider a variety of factors in order to facilitate the realization of positioning. First, the adjacent satellite should have the beam coverage, polarization, frequency band and transponder available in combination with the main satellite, and have the available initial ephemeris to meet the basic conditions for locating the target signal. Secondly, the influence of the satellite spacing on the processing gain should be considered to avoid exceeding the processing capability of the interference source positioning platform (within 12° of the C-band and within 8° of the Ku-band). Third, use the error period analysis tool configured in the system to analyze the error situation of the combination of the selected adjacent star and the main star, and try to avoid the position blind moment when the angle between the position line (especially the time difference position line) is zero. Finally, when the above conditions are satisfied, the available reference stations and on-board signal overlap can be further considered, so as to reduce the complexity of system processing as much as possible. If the existing signals on the satellite cannot meet the requirements of the reference station, the system's own outstation should be adjusted to transmit signals to assist positioning.

In addition to the above preparation conditions, after accepting the positioning task, the antenna and downconverter of the ground station should be adjusted to prepare for receiving signals, and the existence of interference signals in the main satellite transponder should be confirmed by means of spectrum analysis.

2) Parameter setting

After making the necessary preparations, starting the positioning task first requires setting the necessary parameters. There are both mission-related parameters, such as the mission number, frequency and bandwidth parameters of the target signal, and the host star, the selected adjacent star and transponder; there are also parameters related to system processing, such as the coordinates of the receiving station, whether to use the phase or not. Correction and multi-station position correction, general search range of target transmitting station, etc. As shown in Figure 18.

3) Data collection and real-time ephemeris calculation

After completing the parameter setting, the system enters the formal operation interface. According to the previously set task parameters, the collection and storage of the reference signal and the target signal can be started, as shown in Figure 19. At the beginning of data collection, the system also generates satellite ephemeris instantly based on the effective initial ephemeris of the two satellites to provide satellite position and velocity information for final positioning.

In the positioning process, it is assumed that the position and drift speed of the satellite are accurately known, but in the actual use process, some initial forecast values can only be obtained through the Internet or the International Satellite Organization, which cannot meet the needs of instant positioning. In the satellite interference source positioning system, the high-precision orbit prediction model (HPOP) and the precise orbit determination module (PODS) of the satellite toolkit software (STK) are selected, and the high-fidelity mechanical model is used to generate the real-time ephemeris data of the satellite. can meet the requirements of the system. The flow chart of orbit determination is shown in Figure 20.

4) Correlation processing and parameter estimation

After the data collection is completed, the data can be processed and parameter estimated. The DTO/DFO results of the reference signal and the target signal estimated by the signal processing platform, the corresponding signal-to-noise ratio, etc. are given in the form of a list, and the relevant estimation results are written into the database, as shown in Figure 21.

5) Positioning processing and result display

After the parameter estimation is completed, the positioning algorithm can be used to complete the positioning process, and the positioning results can be displayed on the electronic map of the signal monitoring and interference source positioning platform at the same time. The displayed content includes the time difference line and frequency difference line within the search interval set during the establishment of the positioning task, as well as the positioning results obtained by different reference stations.

(4) Check the ground interference source at the vehicle station

As a favorable supplement to the fixed central station, the vehicle-mounted station has important advantages in mobility and flexibility when locating the interference source. The vehicle-mounted station can provide a mobile satellite data receiving link as part of the interference source positioning system , using maritime communication terminals, etc. to realize data and information communication with the fixed central station, after receiving the interference source positioning task issued by the central station, quickly deploy to the target area for detection and ground interference source investigation.

The satellite uplink signal monitoring antenna adopts the form of directional and omnidirectional antennas, covering the above-mentioned satellite frequency bands; the satellite downlink signal monitoring antenna adopts the vehicle-mounted antenna, and the main surface of the antenna is a standard paraboloid, and the target satellite operating frequency band signal can be received by replacing the feed source. The antenna structure is folded, the antenna panel is folded during transportation, and the antenna panel is unfolded during operation, and is accurately positioned by positioning pins. When working, the vehicle should be stopped and leveled. After installing the corresponding frequency band feed, adjust the antenna to aim at the target and start the work.

The vehicle-mounted station is a portable signal monitoring and interference source positioning system as a signal monitoring and interference source positioning platform. It adopts the form of a vehicle-mounted platform. The system's own power supply can meet the normal power consumption of the vehicle and the monitoring system. It needs additional power supply, has good maneuverability and environmental adaptability, can be easily deployed on any terrain in a short period of time, carries necessary spare components, and is equipped with on-board air conditioners, so that it has the ability to operate independently without additional protection.

(5) UAV station to obtain evidence of interference source

The UAV station is used to further supplement and enhance the capabilities of the portable signal monitoring and interference source positioning system. The floating signal monitoring system is used to perform aerial monitoring of satellite uplink signals and forensics of interference source targets.

The floating signal monitoring system is used for close-range monitoring of the uplink signal of the transmitting earth station. It can reduce the application scenarios of poor signal reception quality caused by occlusion by increasing the monitoring height. It is an effective supplement to the vehicle-mounted station. Take advantage of the height advantage to take photos and forensics of the focus of the target.

Aerial monitoring has the advantages of long monitoring distance, flexible setting of monitoring points, and guaranteed line-of-sight receiving effect in complex environments. The ability of seam perception, real-time online signal monitoring and data return can be carried out, which can effectively improve the comprehensive monitoring and control ability of ground signals.

The multi-function silent rotor unmanned aerial vehicle is a kind of unmanned aerial vehicle that has developed rapidly in recent years. This kind of aircraft uses a motor to drive the propeller, and the fuselage is made of carbon fiber. It has high strength, small size, light weight, flexible operation and strong concealment. , safe, reliable, practical and easy to use, the platform is designed with a large load capacity, high ceiling, and a working height of more than 100 meters.

The UAV station uses multi-rotor unmanned aerial vehicles as the carrying platform and ultra-miniaturized monitoring equipment design technology to realize aerial monitoring of radio signals, which is used for radio signal search census, monitoring and surveillance, illegal radiation source direction finding and radiation source location. .

Example

The present invention is based on the working process of the communication satellite interference source positioning system of the satellite communication station, as shown in Figure 22, and mainly includes the following steps:

Step 1: The signal monitoring and interference source positioning platform accesses the satellite information database, sets monitoring equipment and measurement parameters, and formulates and generates a communication satellite interference source positioning task.

Step 2, perform the task of locating the interference source, and describe the process of locating the interference source by taking the Samsung positioning mode as an example.

Step 2(a), create/read/receive positioning tasks.

Step 2(b), analysis of positioning conditions, including analysis of positioning conditions such as neighboring stars, reference stations, ephemeris parameters, and feasibility estimation of positioning parameters.

1) A neighboring star that is compatible with the main star is a necessary condition to achieve three-star positioning, and three-star positioning requires two neighboring stars.

2) Compatibility of neighboring satellites, including forwarding compatibility, coverage compatibility, reference station signal, ephemeris calibration signal and selection of reasonable parameters for rendezvous positioning, etc.

3) Feasibility estimation of positioning parameters.

Step 2(c): Loading the configuration parameters of the positioning work, including the intersection mode, satellite parameters, reference/target parameters, etc. The unified management software in the signal monitoring and interference source positioning platform automatically completes the parameter setting and configuration of the equipment and the system, and at the same time, the system Real-time monitoring and centralized display of equipment running status and task progress.

In step 2(d), the satellite fixed central station performs preliminary positioning of the interference source. According to the satellite orbit information, the unified management software in the signal monitoring and interference source positioning platform decomposes the task parameters, schedules the fixed station antenna to point to the main satellite and neighboring satellites, and at the same time schedules the control reference station to point to the target satellite, and transmits the reference signal at the designated frequency. .

Step 2(e), the fixed central station performs positioning signal sampling and synchronous sampling of the reference and target narrowband signals.

Step 2(f), the fixed central station performs reference and target positioning parameter estimation;

Step 2(g), the fixed central station (reference station) performs ephemeris measurement and error calibration.

Step 2(h), the fixed central station performs TDOA/TDOA intersection positioning and calculation;

The unified management software in the signal monitoring and interference source positioning platform combines the satellite database and the reference station database to perform error analysis on the positioning solution results. If the result does not meet the requirements, an instruction is sent to dispatch the vehicle-mounted station and/or the unmanned aerial vehicle station.

The unified management software combines the satellite database and the reference station database to perform error analysis on the positioning solution results, including confidence ellipse, reference station error, parameter estimation error and geometric error.

In step 2(i), the vehicle-mounted station is used as a favorable supplement to the fixed central station. It is dispatched by the signal monitoring and interference source positioning platform, and is quickly deployed to the target area of the interference source positioning result for approximation search, using the deployed omnidirectional antenna and orientation. The vehicle antenna completes the detection and ground interference source investigation, and forms the interference source investigation report.

In step 2(j), the UAV station is used to further improve the capability of the mobile signal monitoring and interference source positioning system, complete the work such as photographing and spectrum data forensics, and form the interference source forensics report.

Step 3: The unified management software system generates a corresponding task execution report, and stores the signal monitoring and positioning results in a database for preservation and display.

Step 4, the task of locating the interference source ends.

Therefore, a solution method for a communication satellite interference source positioning system based on a satellite communication station proposed by the present invention realizes spectrum monitoring of communication satellites over a user-specified area and precise positioning of interference sources, and obtains a positioning result diagram (FIG. 23).

To sum up, the present invention considers the timeliness and accuracy of communication satellite interference source positioning, and proposes a communication satellite interference source positioning system solution method based on communication satellite stations. The interference source positioning platform is dispatched and managed in a unified manner, and at the same time, the motor vehicle station and the unmanned aerial vehicle station are introduced, which effectively avoids the positioning influence and difficulty caused by the complex ground environment (alpines, forests, buildings, etc.), and realizes the interference radiation source. Precise positioning greatly improves the positioning capability and reliability of the communication satellite interference source positioning system.

Descriptions of the calculation parameters referenced in the formula are shown in the table below.

The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art. The usual changes and substitutions made by those skilled in the art within the scope of the technical method of the present invention should be included in the protection scope of the present invention.

The parts not described in detail in the present invention belong to the common knowledge of those skilled in the art.

Claims (8)

1. based on the communication satellite interference source positioning system of satellite communication station, it is characterized in that: comprise satellite communication station and signal monitoring and interference source positioning platform; Described satellite communication station comprises fixed central station, motor vehicle on-board station and unmanned aerial vehicle stand; The signal monitoring and interference source positioning platform generates a mission plan according to the user's business needs, and sends scheduling instructions to the fixed central station, motor vehicle station and/or UAV station in the satellite communication station according to the mission plan; The fixed central station responds to the scheduling instruction scheduling, is used to complete the initial positioning of the interference source, and sends the initial positioning information to the signal monitoring and interference source positioning platform; The motor vehicle on-board station responds to the scheduling instruction scheduling, is used for performing mobile positioning tasks and completes the investigation of ground interference sources, and sends the investigation results to the signal monitoring and interference source positioning platform; The unmanned aerial vehicle station responds to the scheduling instruction scheduling, is used for spectrum data forensics for the designated interference source, and sends the acquired spectrum data to the signal monitoring and interference source positioning platform; The signal monitoring and interference source positioning platform adjusts the mission plan in real time according to the information fed back by the satellite communication station, sends scheduling instructions to the corresponding satellite communication station according to the new mission plan, and finally locates the interference source according to the information fed back by the satellite communication station. 2 . The system according to claim 1 , wherein the fixed central station adopts a synchronous double-star or three-star positioning mode to perform preliminary positioning of the interference source. 3 . 3. system according to claim 2, is characterized in that: target signal is the modulation signal that fixed central station transmits, directly adopts two time difference (TDOA) position lines or two frequency difference (TDOA) position lines under dual-star positioning mode It is enough to perform a rendezvous positioning process; for some special signals or application scenarios, including the positioning of moving target signals or unmodulated signals (CW signals and CW frequency sweep signals) emitted by fixed targets, the Samsung positioning mode needs to be used for positioning. Signal cancellation and signal preprocessing to enhance the adaptability to neighboring satellite signal conditions and target signal conditions. 4. The system according to claim 2, wherein: the three-star positioning mode includes three target satellites, one of which is used as the main satellite, and the other two are compatible with the main satellite as adjacent satellites; one is selected as a reference in the fixed central station station, the rest are used as positioning stations, each positioning station correspondingly collects the signal of a target satellite; According to the mission plan, schedule the positioning antenna of the positioning station to point to the main and adjacent satellites, configure the receiving link equipment and the L-band switch matrix; Control the reference station to point to the target satellite and transmit the reference signal at the designated frequency; According to the task loading work configuration parameters, the target and reference signals are collected synchronously, the sampling data of the main adjacent satellite signal is obtained, the sampled data is subjected to mutual fuzzy correlation processing, and the time difference of arrival TDOA and the main adjacent star generated by the different paths of the signal passing through the main adjacent satellite are extracted. The arrival frequency difference FDOA caused by the Doppler frequency shift caused by the different relative velocities of the on-orbit perturbation completes the positioning parameter estimation; Using the satellite ephemeris data to solve the positioning equation, the time difference position line and the frequency difference position line are obtained, and the best positioning point is obtained by the intersection of the two lines. 5. The system according to claim 4, wherein the compatibility of adjacent satellites includes forwarding compatibility, coverage compatibility, reference station signal, ephemeris calibration signal and selected parameters for rendezvous positioning. 6. The system according to claim 5, wherein the adjacent stars are selected in the following manner: First, the adjacent satellite should have the beam coverage, polarization, frequency band and transponder available in combination with the main satellite, and have the available initial ephemeris to meet the basic conditions for locating the target signal; Secondly, consider the influence of the satellite distance on the processing gain to avoid exceeding the processing capability of the signal monitoring and interference source location platform; Finally, analyze the error situation of the combination of the selected neighbor star and the main star, and avoid the positioning blind moment when the angle between the positioning line is zero. 7. The system according to claim 1, characterized in that: a satellite downlink signal monitoring antenna is mounted on the vehicle on-board station, the antenna adopts a vehicle-mounted antenna, the main surface of the antenna is a standard paraboloid, and the antenna structure is a folding mode, When transporting, the antenna panel is folded, and when working, the antenna panel is unfolded, and the positioning pin is used for accurate positioning; when working, the vehicle is stopped and leveled, and after installing the corresponding frequency band feed, adjust the antenna to align the target to work. 8. system according to claim 1 is characterized in that: described unmanned aerial vehicle station adopts multi-rotor unmanned aerial vehicle as carrying platform, utilizes floating signal monitoring technology to monitor the uplink signal of transmitting earth station and interfere source target Site photo forensics.

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