Any satellite non-cooperative positioning method and device

Abstract

The invention discloses an arbitrary satellite non-cooperative positioning method and device, and the method comprises the steps: extracting the Doppler information of each satellite at different observation moments according to the carrier signals, received at different observation moments, of a plurality of satellites; according to the extracted Doppler information, constructing an equation set which takes time and Doppler frequency shift as known quantities and takes satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities; and solving the equation set to obtain the coordinates of the receiver. According to the method, the signal of any satellite passing through the top is received, Doppler information is extracted, an equation set is constructed, the position coordinates of the receiver are calculated, and navigation positioning when the GNSS is interfered or suppressed is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of navigation and positioning, and in particular relates to a method and device for non-cooperative positioning of arbitrary satellites. Background Art

[0002] Normally, GNSS (Global Navigation Satellite System) can be used for navigation and positioning. However, under certain conditions, such as when GNSS is interfered with or suppressed, it cannot be used. Although inertial navigation can be used for a short period of time, the problem of accumulated error of inertial navigation is more obvious. Summary of the invention

[0003] In order to solve the navigation and positioning problem when GNSS is interfered with or suppressed, the present invention provides a method and device for non-cooperative positioning of arbitrary satellites, which receives the signal of any satellite passing overhead, extracts Doppler information and constructs a set of equations to calculate the receiver coordinates, thereby realizing navigation and positioning when GNSS is interfered with or suppressed.

[0004] According to one aspect of the present invention, a method for non-cooperative positioning of any satellite is provided, comprising:

[0005] According to the carrier signals of multiple satellites received at different observation times, the Doppler information of each satellite at different observation times is extracted;

[0006] Based on the extracted Doppler information, a set of equations is constructed with time and Doppler frequency shift as known quantities and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities;

[0007] Solve the equations to obtain the coordinates of the receiver.

[0008] As a further technical solution, the method further includes: setting the relationship between the number of observations M and the number of satellites N to satisfy: M×N>7×N+3.

[0009] As a further technical solution, the method further includes: receiving carrier signals of multiple satellites at different observation times according to a set number of observation times.

[0010] As a further technical solution, after receiving carrier signals of multiple satellites at different observation times, the method further includes:

[0011] Calculating the position and velocity of each of the satellites at different observation times;

[0012] Calculating the relative speed between each of the satellites and the receiver at different observation times;

[0013] The Doppler frequency shift of each satellite at different observation times is calculated according to the relative speed.

[0014] As a further technical solution, after obtaining the Doppler frequency shift of each satellite at different observation times, the method further includes:

[0015] According to the Doppler shift formula, equations are constructed for each satellite at different observation times;

[0016] A set of equations is formed according to equations of the plurality of satellites at different observation times.

[0017] As a further technical solution, solving the equation group includes: using the least square method or Newton's method to solve the equation group.

[0018] According to one aspect of the present invention, there is provided a device for non-cooperative positioning of any satellite, comprising:

[0019] A signal extraction module, used to extract Doppler information of each satellite at different observation times based on carrier signals of multiple satellites received at different observation times;

[0020] The signal solving module is used to construct a set of equations with time and Doppler frequency shift as known quantities and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities based on the extracted Doppler information, and solve the set of equations to obtain the coordinates of the receiver.

[0021] According to one aspect of the present invention, there is provided a receiver equipped with the device for non-cooperative positioning of any satellite.

[0022] According to one aspect of the present invention, there is provided a receiver, comprising: a radio frequency front-end component for receiving satellite signals; a signal sampling and digitization component for sampling and digitally converting received satellite signals; a signal demodulation and frequency analysis component for processing the converted signals and extracting Doppler information of the satellite; a positioning calculation component for constructing a set of equations with time and Doppler frequency shift as known quantities and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities based on the extracted Doppler information, and solving the set of equations to obtain the coordinates of the receiver.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The arbitrary satellite non-cooperative positioning method proposed in the present invention can receive signals from any satellite passing overhead, extract Doppler information and construct a set of equations for calculation, so as to locate the receiver without knowing the orbital parameters of these satellites, thereby realizing navigation positioning when the GNSS is interfered or suppressed. In addition, the present invention can obtain satellite orbital parameters and carrier frequencies for other purposes while obtaining the receiver coordinates. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings used in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A schematic diagram of the principle of a method for non-cooperative positioning of arbitrary satellites provided in an embodiment of the present invention.

[0027] Figure 2 A schematic diagram of a specific process of solving a receiver position provided by an embodiment of the present invention.

[0028] Figure 3 A structural schematic diagram of a receiver provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] It should be noted that:

[0030] In view of the current situation that GNSS cannot be used when it is interfered with or suppressed, and using inertial navigation for short-term supplementation will lead to more obvious cumulative errors, the present invention provides an arbitrary satellite non-cooperative positioning method, which can be used as an alternative navigation and positioning solution when GNSS is interfered with or suppressed.

[0031] The prior art also uses some technical means to solve the problem of difficulty in achieving high-precision navigation when the signal is interfered or destroyed. However, the current prior art still needs to rely on satellite orbit data to calculate the position of the satellite. In actual situations, in non-cooperative positioning, satellite orbit data is difficult to obtain (some are confidential, and more are not guaranteed in terms of accuracy and timeliness). Moreover, when the position is unknown, it is difficult to identify the satellite to which the received satellite signal belongs, so it is difficult to match the received signal with the satellite orbit. Compared with the prior art, the method of the present invention does not need to care about the satellite's orbit data, and can directly solve its own position, thereby improving availability and reliability.

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention are arbitrarily combined with each other to form a new technical solution. This combination is not restricted by the sequence of steps and / or the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that this combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] See also Figure 1 An embodiment of the present invention provides a method for non-cooperative positioning of arbitrary satellites. First, based on the carrier signals of multiple satellites received at different observation times, the Doppler information of each satellite at different observation times is extracted; then, based on the extracted Doppler information, a set of equations is constructed with time and Doppler frequency shift as known quantities, and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities; finally, the set of equations is solved to obtain the coordinates of the receiver.

[0034] It should be noted that when the satellite is in motion, the receiver will generate a Doppler effect when receiving satellite signals. Since the Doppler effect is related to relative velocity, at different times and for different satellites, there will be multiple equal Doppler surfaces (or equal relative velocity surfaces), and equal Doppler change surfaces (or equal relative acceleration surfaces), which are usually hyperboloids, conical surfaces, spherical surfaces or hyperspheres. The position of the receiver can be obtained by finding the intersection of these surfaces. Therefore, the embodiment of the present invention receives carrier signals of multiple satellites at different times, extracts the Doppler information of each satellite at different times, constructs a set of equations with time and Doppler frequency shift as known quantities, and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown variables, and solves this set of equations to obtain the coordinates of the receiver, that is, complete positioning, and at the same time, the satellite orbit parameters and carrier frequency can also be obtained for other uses.

[0035] In the embodiment of the present invention, since there are a large number of satellites in the sky, there are more than 6,000 low-orbit communication satellites (LEO) and medium-orbit communication satellites (MEO) alone, and there are hundreds of visible satellites at any location, which is sufficient to complete non-cooperative mode positioning.

[0036] It should be noted that, in the process of solving the receiver position in the embodiment of the present invention, the known quantities involved include:

[0037] tj : Observation time, j-th observation, j=1,2,…,M.

[0038] Δf i,j : The Doppler shift received by the i-th satellite at the j-th observation, i = 1, 2, ..., N, j = 1, 2, ..., M. N is the number of satellites received in the observation, and M is the number of observations for each satellite.

[0039] c: speed of light.

[0040] The unknowns involved include:

[0041] r rec =(x rec ,y rec ,z rec ): The location (coordinates) of the receiver.

[0042] f i0 : The carrier frequency of the ith satellite.

[0043] a i ,e i ,i i ,Ω i ,ω i ,M i : Orbital parameters of the ith satellite.

[0044] For each satellite, there are 7 unknowns. If there are N satellites, there are a total of 7×N+3 unknowns. Therefore, if you want to solve an overdetermined equation, the product of the number of observations M and the number of satellites N must be greater than the number of unknowns, that is, M×N>7×N+3. It can generally be assumed that the number of observations must be greater than 7.

[0045] See also Figure 2 After receiving the carrier signals of multiple satellites at different observation times, the receiver position solution process specifically includes the following steps:

[0046] Step 1: Calculation of satellite position and velocity

[0047] According to Kepler's equation, the satellite's mean anomaly angle M i (t j ) and the eccentric anomaly angle E i (t j ) is:

[0048] M i (t j )=E i (t j )-e i sin(E i (t j ))

[0049] Among them, M i (t j ) is the mean anomaly angle, E i (t j ) is the angle of approach, e i is the eccentricity of the satellite. i (t j ) can be solved by numerical methods (such as Newton's method). However, since the satellite parameters are unknown, the time for receiving satellites is short, and satellites are mainly LEO and MEO with small eccentricity, the following formula can be used for approximation:

[0050]

[0051] Satellite position calculation:

[0052] The satellite's instantaneous true anomaly v i (t j ) and the eccentric anomaly angle E i (t j ) is:

[0053]

[0054] Satellite position r i (t j )=(x i (t j) ,y i (t j ),z i (t j ))for:

[0055]

[0056] Among them, a i is the semi-major axis of the satellite, e i is the eccentricity, v i (t j ) is the instantaneous true anomaly, E i (t j ) is the periapsis angle.

[0057] Satellite speed calculation:

[0058] The speed of the satellite v i (t j )=(v xi (t j) ,v yi (t j ),v zi (t j )) is the derivative of the satellite position with respect to time:

[0059]

[0060] Step 2: Calculation of relative speed

[0061] The receiver's position is r rec =(x rec ,y rec ,z rec ), the satellite position is r i (t j ), the satellite’s velocity is v i (t j ), then the relative position vector r between the receiver and the satellite i,rec (t j )for:

[0062] r i,rec (t j )=r i (t j )-r rec

[0063] Relative speed v rel,i (t j ) is the velocity component between the satellite and the receiver, along the line of sight between the receiver and the satellite:

[0064]

[0065] Step 3: Calculation of Doppler shift

[0066] Based on the relative speed v rel,i (t j ), the Doppler frequency shift Δf can be calculated i,j :

[0067]

[0068] Where: c is the speed of light, f i0 is the carrier frequency of the ith satellite, v rel,i (t j ) is the relative speed between the satellite and the receiver.

[0069] Step 4: Construct the system of equations

[0070] According to the Doppler shift formula, equations are constructed here for each satellite at different observation times:

[0071]

[0072] In this equation, Δf i,j is the known Doppler shift r i (t j ) and vi (t j ) is given by the orbital parameter θ i =(a i ,e i ,i i ,Ω i ,ω i ,M i ) indicates that f i0 is the satellite carrier frequency, and the receiver coordinates r rec =(x rec ,y rec ,z rec ) is the unknown quantity to be solved.

[0073] Step 5: Solve the system of equations

[0074] After obtaining the equation group, since there are N satellites, each satellite has Doppler frequency shift data at M observation times, that is, this equation group consists of N×M equations. By solving this nonlinear equation group, the three-dimensional coordinates r of the receiver can be obtained. rec =(x rec ,y rec ,z rec ), and the orbital parameters and carrier frequencies of all satellites can also be obtained.

[0075] Common solution methods include least squares method or Newton's method.

[0076] When the least squares method is used to solve a nonlinear system of equations, the minimized error function is as follows:

[0077]

[0078] When using Newton's method to solve the nonlinear equations, update the receiver coordinates r rec until the error is minimized.

[0079] It should be understood that any technology not described in detail in the specification of the present invention may be regarded as conventional technical means or common knowledge in the art.

[0080] Based on the same inventive concept as the above-mentioned method embodiment, an embodiment of the present invention also provides a device for non-cooperative positioning of arbitrary satellites, including: a signal extraction module, used to extract the Doppler information of each satellite at different observation times based on the carrier signals of multiple satellites received at different observation times; a signal solution module, used to construct a group of equations with time and Doppler frequency shift as known quantities, and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities based on the extracted Doppler information, and solve the group of equations to obtain the coordinates of the receiver.

[0081] The device for non-cooperative positioning of arbitrary satellites provided in an embodiment of the present invention receives signals from arbitrary satellites passing overhead, constructs a set of equations based on Doppler information of multiple satellites at different observation times, and calculates the position of the receiver, thereby achieving positioning without knowing the satellite orbit parameters, and solving the problem of navigation positioning when GNSS is interfered with or suppressed.

[0082] Based on the same inventive concept as the above method embodiment, the embodiment of the present invention further provides a receiver, which is equipped with the device for non-cooperative positioning of any satellite. The receiver provided by the embodiment of the present invention can realize navigation positioning by using the device for non-cooperative positioning of any satellite when the GNSS is interfered or suppressed, thereby avoiding the cumulative error problem faced by using inertial navigation for supplementary positioning.

[0083] Based on the same inventive concept as the above method embodiment, the present invention also provides a receiver, see Figure 3 , including: a radio frequency front-end component for receiving satellite signals; a signal sampling and digitization component for sampling and digitalizing the received satellite signals; a signal demodulation and frequency analysis component for processing the converted signals and extracting the Doppler information of the satellite; a positioning calculation component for constructing a set of equations with time and Doppler frequency shift as known quantities and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities based on the extracted Doppler information, and solving the set of equations to obtain the coordinates of the receiver.

[0084] The receiver provided in the embodiment of the present invention adopts an SDR architecture. In the receiver system, the RF front end (RFFront-End) is used to receive satellite signals and convert them into signals suitable for further processing. The RF front end mainly includes an antenna, an amplifier, a filter, a frequency converter, etc., which are used to receive satellite signals of different frequency bands.

[0085] Specifically, the design of the RF front end mainly includes antenna, low noise amplifier (LNA), filter, mixer, etc. The specific design is as follows:

[0086] Antenna: In order to receive signals from satellites, the receiver needs to design an antenna that supports multiple satellite frequency bands. Multi-frequency antennas can be used to enable them to work effectively in multiple frequency bands.

[0087] Low noise amplifier: After receiving the satellite signal, the low noise amplifier performs preliminary amplification to ensure the signal quality. The LNA needs to be designed to be low noise and broadband, able to support multiple frequency bands.

[0088] Filter: The filter is used to select the frequency band of interest. At the same time, it can suppress spurious signals to ensure the accuracy of subsequent signal processing.

[0089] Mixer: The mixer converts the received satellite signals of different frequency bands into intermediate frequencies (IF) for subsequent digital processing.

[0090] In the receiver system, the signal sampling and digitization (ADC / DSP) samples the analog signal obtained from the RF front end and converts it into a digital signal for processing by the SDR.

[0091] Specifically, the received RF signal is sampled by an analog-to-digital converter (ADC). Selecting the right sampling rate is key to ensure that the signal is not distorted, especially in the case of large Doppler shifts.

[0092] Sampling rate selection: According to the Nyquist theorem, the sampling rate should be higher than twice the signal bandwidth. For satellite signals, the sampling rate is usually selected to be tens of MHz to hundreds of MHz to ensure accurate capture of Doppler frequency shift and other signal characteristics.

[0093] Dynamic range: A large enough dynamic range is needed to capture signals from different satellites, which can vary greatly in strength.

[0094] In this receiver system, signal demodulation and frequency analysis (SDR processing) are performed in the digital domain, including filtering, frequency synchronization, Doppler estimation, phase tracking, etc., to extract frequency changes and signal characteristics received from the satellite.

[0095] The SDR part is responsible for processing the received signal, and the main steps include frequency synchronization and Doppler estimation.

[0096] Frequency synchronization: Due to the Doppler effect of the satellite, the frequency of the signal will shift. The SDR receiver needs to be frequency synchronized to ensure that the frequency of the signal is demodulated correctly. The synchronization process usually includes automatic frequency control (AFC) or fine synchronization through the baseband portion of the signal.

[0097] Doppler Estimation: The Doppler shift is related to the speed of the satellite relative to the receiver. The receiver needs to estimate the Doppler shift from the satellite signal. The Doppler shift estimation can be achieved by spectrum analysis of the received signal, sliding Fourier transform (FFT) or phase-locked loop, frequency and phase tracking algorithm of the frequency-locked loop.

[0098] In this receiver system, the processor part is used for positioning calculation and solution, and calculates the three-dimensional position of the receiver based on the geometric relationship between the frequency offsets of multiple satellites and the receiver position.

[0099] Once the Doppler frequency shift data from multiple satellites is obtained, the data can be handed over to the processor part to form a set of equations, which can be solved according to the numerical processing method to obtain information such as the receiver's coordinates and satellite parameters to complete the positioning.

[0100] Furthermore, while completing the positioning, satellite orbit parameters and carrier frequency can also be obtained for other uses.

[0101] In summary, the present invention takes into account that when the satellite is in motion, the receiver will generate the Doppler effect when receiving the satellite signal. Since the Doppler effect is related to the relative speed, there will be multiple equal Doppler surfaces and equal Doppler change surfaces at different times and for different satellites. The intersection of these surfaces can be obtained to obtain the position of the receiver. Therefore, the present invention receives the carrier signals of multiple satellites at different times, extracts the Doppler information of each satellite at different times, constructs a set of equations with time and Doppler frequency shift as known quantities, and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown variables, and solves this set of equations to obtain the coordinates of the receiver, that is, complete the positioning. The present invention can perform receiver position calculation without knowing the orbit parameters of the satellite, and realize navigation positioning when the GNSS is interfered or suppressed. In addition, while obtaining the receiver coordinates, the present invention can also obtain the satellite orbit parameters and carrier frequency for other uses.

[0102] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices. The flowcharts shown in the accompanying drawings are merely exemplary and do not necessarily include all the contents and operations / steps, nor do they necessarily have to be executed in the order described. For example, some operations / steps may be further decomposed, while some operations / steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

[0103] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions, for example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to the steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A method for non-cooperative positioning of arbitrary satellites, characterized in that: include: According to the carrier signals of multiple satellites received at different observation times, the Doppler information of each satellite at different observation times is extracted; Based on the extracted Doppler information, a set of equations is constructed with time and Doppler frequency shift as known quantities and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities; Solve the equations to obtain the coordinates of the receiver.

2. The method for non-cooperative positioning of arbitrary satellites according to claim 1, characterized in that: The method further includes: setting the relationship between the number of observations M and the number of satellites N to satisfy: M×N>7×N+3.

3. The method for non-cooperative positioning of arbitrary satellites according to claim 2, characterized in that: The method further comprises: receiving carrier signals of a plurality of satellites at different observation times according to a set number of observation times.

4. The method for non-cooperative positioning of arbitrary satellites according to claim 1 or 3, characterized in that: After receiving carrier signals from multiple satellites at different observation times, it also includes: Calculating the position and velocity of each of the satellites at different observation times; Calculating the relative speed between each of the satellites and the receiver at different observation times; The Doppler frequency shift of each satellite at different observation times is calculated according to the relative speed.

5. The method for non-cooperative positioning of arbitrary satellites according to claim 4, characterized in that: After obtaining the Doppler frequency shift of each satellite at different observation times, the method further includes: According to the Doppler shift formula, equations are constructed for each satellite at different observation times; A set of equations is formed according to equations of the plurality of satellites at different observation times.

6. The method for non-cooperative positioning of arbitrary satellites according to claim 1 or 5, characterized in that: Solving the system of equations includes: using a least squares method or a Newton method to solve the system of equations.

7. An apparatus for non-cooperative positioning of arbitrary satellites, characterized in that: include: A signal extraction module, used to extract Doppler information of each satellite at different observation times based on carrier signals of multiple satellites received at different observation times; The signal solving module is used to construct a set of equations with time and Doppler frequency shift as known quantities and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities based on the extracted Doppler information, and solve the set of equations to obtain the coordinates of the receiver.

8. A receiver, characterized in that: A device for non-cooperative positioning of any satellite is provided as claimed in claim 7.

9. A receiver, characterized in that: include: RF front-end components for receiving satellite signals; A signal sampling and digitization component, used for sampling and digitizing received satellite signals; The signal demodulation and frequency analysis component is used to process the converted signal and extract the Doppler information of the satellite; the positioning calculation component is used to construct a set of equations with time and Doppler frequency shift as known quantities and satellite orbit parameters, satellite carrier frequency and receiver coordinates as unknown quantities based on the extracted Doppler information, and solve the set of equations to obtain the coordinates of the receiver.

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