A fast doppler positioning method based on opportunity signals

Abstract

This invention provides a fast Doppler localization method based on opportunistic signals. The method includes: establishing instantaneous Doppler frequency shift measurements for each satellite based on the receiver's initial position and velocity information, the wavelength of the opportunistic signal, and the position and velocity information of each satellite; establishing an instantaneous Doppler localization equation based on the relationship between the instantaneous Doppler frequency shift measurements for each satellite and the receiver's position information; determining regularization parameters using the variance expansion factor method; obtaining constraint parameters based on the regularization parameters and the stable functional; and solving the instantaneous Doppler localization equation under the condition of minimizing the constraint parameters to obtain the instantaneous Doppler localization result based on the opportunistic signal. The localization result includes the receiver's final position information, final velocity information, and frequency offset.

Description

Technical Field

[0001] This invention relates to the fields of radio navigation, signal and information processing technology, and in particular to a fast Doppler positioning method based on opportunistic signals. Background Technology

[0002] Global Navigation Satellite System (GNSS) plays an important role in military, maritime, and transportation sectors. However, due to its inherent vulnerability, it is easily interfered with, whether intentionally or unintentionally, and may malfunction. To reduce dependence on GNSS or to compensate for its weaknesses, navigation via signals of opportunity (SOP), such as low-Earth orbit communication signals, broadcast television signals, and public mobile communication signals, can be implemented.

[0003] With the rapid development and construction of giant low-Earth orbit (LEO) internet constellations in recent years, a large number of high-quality signal resources have been provided for opportunistic signal navigation. Compared with the Global Navigation Satellite System (GNSS), LEO opportunistic signal navigation has the following advantages: 1) LEO satellites have low orbits, small weight, and low satellite and launch costs, and can be launched in a single launch with multiple satellites; 2) Since the orbital altitude of LEO satellites is generally below 1000km, compared with medium- and high-Earth orbit navigation satellites at 20000-35000km, their signal transmission paths are shorter, signal delays are smaller, and power losses are lower. Under the same signal transmission power, the landing signal power reaching the Earth's surface can be 30dB higher (i.e., 1000 times), which can improve the positioning availability in urban canyons or complex electromagnetic environments; 3) LEO satellites operate at higher speeds and have longer trajectories in the same time period. One minute of LEO satellite operation is roughly equivalent to 20 minutes of geometric configuration change for a current medium-Earth orbit satellite. The correlation between observation equations between adjacent epochs is greatly reduced, and various errors can be estimated and separated more quickly when estimating positioning parameters. Therefore, by receiving low-Earth orbit opportunity signals and extracting Doppler measurement information, constructing instantaneous Doppler observation equations, and using satellite orbit information obtained by combining satellite two-line elements (TLE) data with orbit prediction models, navigation and positioning solutions that do not rely on satellite navigation can be achieved.

[0004] Opportunistic navigation based on low-Earth orbit (LEO) opportunity signals can achieve Doppler navigation and positioning under navigation satellite rejection conditions. However, due to their lower orbits, the signal coverage area of ​​LEO satellites is much smaller than that of navigation satellite signals. Therefore, there are situations where the number of visible satellites is relatively small. In such cases, the stability of the least-squares estimates of parameters drops sharply, and even small noise fluctuations can lead to serious deviations in the estimation results. Therefore, Doppler positioning calculations require accumulation over multiple time intervals, and currently still require a certain convergence time (typically around 10 minutes) to achieve accuracy at the hundred-meter level, becoming a major factor restricting its widespread engineering application. Summary of the Invention

[0005] This invention provides a fast Doppler localization method based on opportunistic signals, which can solve the above-mentioned technical problems.

[0006] This invention provides a fast Doppler localization method based on opportunity signals, the method comprising:

[0007] The instantaneous Doppler frequency shift measurement value for each satellite is established based on the receiver's initial position and initial velocity information, the wavelength of the opportunity signal, and the position and velocity information of each satellite.

[0008] An instantaneous Doppler positioning equation is established based on the relationship between the instantaneous Doppler frequency shift measurement value corresponding to each satellite and the position information of the receiver;

[0009] The regularization parameter is determined by the variance expansion factor method. The constraint parameter is obtained based on the regularization parameter and the stable functional. The instantaneous Doppler positioning equation is solved under the condition of minimizing the constraint parameter to obtain the instantaneous Doppler positioning result based on the opportunistic signal. The positioning result includes the receiver's final position information, final velocity information and frequency offset.

[0010] Preferably, the instantaneous Doppler frequency shift measurement value for each satellite is established using the following formula:

[0011]

[0012] In the formula, f d The instantaneous Doppler frequency shift measurement is represented by λ, where λ represents the wavelength of the opportunity signal, and v s and v represent the satellite's velocity information and the receiver's initial velocity information, respectively, r s and r represent the satellite's position information and the receiver's initial position information, respectively.

[0013] Preferably, the instantaneous Doppler localization equation is established using the following formula:

[0014]

[0015] in,

[0016] In the formula, Let H denote the partial derivative of the instantaneous Doppler frequency shift measurement vector, and let H denote the Jacobian matrix. These represent the receiver's velocities in the x, y, and z directions, respectively. Let represent the partial derivative of the unit vector along the line-of-sight direction from the i-th satellite to the receiver, where i = 1, 2, 3, ..., k, and k represents the total number of satellites. This represents the partial derivative of the velocity of the i-th satellite minus the velocity component along the line-of-sight direction. Let δx, δy, and δz represent the partial derivatives of the pseudorange, and let δx, δy, and δz represent the positions of the receiver in the x, y, and z directions, respectively. ε' represents the receiver's frequency offset, and ε′ represents the linearization error vector.

[0017] Preferably, the constraint parameters are obtained by the following formula:

[0018]

[0019] In the formula, A represents the constraint parameter. Here, Hx represents the instantaneous Doppler prediction vector, y represents the instantaneous Doppler frequency shift measurement vector, α represents the regularization parameter greater than 0, Ω(x) represents the stable functional, and R represents the regularization matrix.

[0020] Preferably, the instantaneous Doppler localization result based on the chance signal is obtained by the following formula:

[0021]

[0022] In the formula, This represents the instantaneous Doppler localization result based on the chance signal, where I represents the identity matrix.

[0023] The technical solution of this invention utilizes the Doppler frequency shift of satellite signals caused by the relative motion between the satellite and the receiver to reflect the relative relationship between the satellite's position and velocity and the receiver's position and velocity. A biased ridge estimation method is employed to achieve fast opportunistic signal navigation and positioning based on frequency measurement information. Furthermore, by introducing a stable functional during least-squares estimation, the invention reduces the massive positioning errors caused by the singularity of the observation matrix when available opportunity signals are limited, significantly shortening the convergence time to obtain stable and reliable instantaneous Doppler positioning results. This invention can be used for radio navigation and positioning under navigation satellite rejection conditions, as well as for combined navigation with inertial information to correct long-term pure inertial navigation errors, demonstrating promising military and civilian applications. Attached Figure Description

[0024] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0025] Figure 1 A flowchart of a fast Doppler localization method based on chance signals according to an embodiment of the present invention is shown;

[0026] Figure 2 A schematic diagram of a fast Doppler localization method based on chance signals according to an embodiment of the present invention is shown. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0030] like Figure 1 and Figure 2 As shown, this invention provides a fast Doppler localization method based on opportunity signals, the method comprising:

[0031] The instantaneous Doppler frequency shift measurement value for each satellite is established based on the receiver's initial position and initial velocity information, the wavelength of the opportunity signal, and the position and velocity information of each satellite.

[0032] An instantaneous Doppler positioning equation is established based on the relationship between the instantaneous Doppler frequency shift measurement value corresponding to each satellite and the position information of the receiver;

[0033] The regularization parameter is determined by the variance expansion factor method. The constraint parameter is obtained based on the regularization parameter and the stable functional. The instantaneous Doppler positioning equation is solved under the condition of minimizing the constraint parameter to obtain the instantaneous Doppler positioning result based on the opportunistic signal. The positioning result includes the receiver's final position information, final velocity information and frequency offset.

[0034] In this invention, a stable functional Ω(x) is introduced during the solution process to improve the ill-conditioned nature of the instantaneous Doppler positioning equation.

[0035] This invention utilizes the Doppler frequency shift of satellite signals caused by the relative motion between the satellite and the receiver to reflect the relative relationship between the satellite's position and velocity and the receiver's position and velocity. A biased ridge estimation method is employed to achieve fast opportunistic signal navigation and positioning based on frequency measurement information. Furthermore, by introducing a stable functional during least-squares estimation, the invention reduces the massive positioning errors caused by the singularity of the observation matrix when available opportunity signals are limited, significantly shortening the convergence time to obtain stable and reliable instantaneous Doppler positioning results. This invention can be used for radio navigation and positioning under navigation satellite rejection conditions, as well as for combined navigation with inertial information to correct long-term pure inertial navigation errors, demonstrating promising military and civilian applications.

[0036] According to one embodiment of the present invention, the instantaneous Doppler frequency shift measurement value corresponding to each satellite is established by the following formula:

[0037]

[0038] In the formula, f d The instantaneous Doppler frequency shift measurement is represented by λ, where λ represents the wavelength of the opportunity signal, and v s and v represent the satellite's velocity information and the receiver's initial velocity information, respectively, r s and r represent the satellite's position information and the receiver's initial position information, respectively.

[0039] According to one embodiment of the present invention, the instantaneous Doppler localization equation is established by the following formula:

[0040]

[0041] in,

[0042] In the formula, Let H denote the partial derivative of the instantaneous Doppler frequency shift measurement vector, and let H denote the Jacobian matrix. These represent the receiver's velocities in the x, y, and z directions, respectively. Let represent the partial derivative of the unit vector along the line-of-sight direction from the i-th satellite to the receiver, where i = 1, 2, 3, ..., k, and k represents the total number of satellites. This represents the partial derivative of the velocity of the i-th satellite minus the velocity component along the line-of-sight direction. Let δx, δy, and δz represent the partial derivatives of the pseudorange, and let δx, δy, and δz represent the positions of the receiver in the x, y, and z directions, respectively. ε' represents the receiver's frequency offset, and ε′ represents the linearization error vector.

[0043] According to one embodiment of the present invention, the constraint parameters are obtained by the following formula:

[0044]

[0045] In the formula, A represents the constraint parameter. Here, Hx represents the instantaneous Doppler prediction vector, y represents the instantaneous Doppler frequency shift measurement vector, α represents the regularization parameter greater than 0, Ω(x) represents the stable functional, and R represents the regularization matrix.

[0046] According to one embodiment of the present invention, the instantaneous Doppler localization result based on the chance signal is obtained by the following formula:

[0047]

[0048] In the formula, This represents the instantaneous Doppler localization result based on the chance signal, where I represents the identity matrix.

[0049] In summary, this invention provides a fast Doppler positioning method based on opportunistic signals. It utilizes the Doppler frequency shift of satellite signals caused by the relative motion between the satellite and the receiver to reflect the relative relationship between the satellite's position and velocity and the receiver's position and velocity. A biased ridge estimation method is employed to achieve fast opportunistic signal navigation and positioning based on frequency measurement information. Furthermore, by introducing a stable functional during least-squares estimation, the invention reduces the massive positioning errors caused by the singularity of the observation matrix when available opportunistic signals are limited, significantly shortening the convergence time to obtain stable and reliable instantaneous Doppler positioning results. This invention can be used for radio navigation and positioning under navigation satellite rejection conditions, as well as for combined navigation with inertial information to correct long-term pure inertial navigation errors, demonstrating promising military and civilian applications.

[0050] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0051] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fast Doppler localization method based on chance signals, characterized in that, The method includes: The instantaneous Doppler frequency shift measurement value for each satellite is established based on the receiver's initial position and initial velocity information, the wavelength of the opportunity signal, and the position and velocity information of each satellite. An instantaneous Doppler positioning equation is established based on the relationship between the instantaneous Doppler frequency shift measurement value corresponding to each satellite and the position information of the receiver; The regularization parameter is determined by the variance expansion factor method. The constraint parameter is obtained based on the regularization parameter and the stable functional. The instantaneous Doppler positioning equation is solved under the condition of minimizing the constraint parameter to obtain the instantaneous Doppler positioning result based on the opportunistic signal. The positioning result includes the receiver's final position information, final velocity information and frequency offset.

2. The method according to claim 1, characterized in that, The instantaneous Doppler frequency shift measurement for each satellite is established using the following formula: where f d represents the instantaneous Doppler shift measurement, λ represents the wavelength of the opportunity signal, v s and v represent the satellite's velocity information and the receiver's initial velocity information, respectively, r s and r represent the satellite's position information and the receiver's initial position information, respectively.

3. The method according to claim 1, characterized in that, The instantaneous Doppler localization equation is established using the following formula: in, In the formula, H represents the partial derivative of the instantaneous Doppler frequency shift measurement vector, and H represents the Jacobian matrix. These represent the receiver's velocities in the x, y, and z directions, respectively. Let represent the partial derivative of the unit vector along the line-of-sight direction from the i-th satellite to the receiver, where i = 1, 2, 3, ..., k, and k represents the total number of satellites. This represents the partial derivative of the velocity of the i-th satellite minus the velocity component along the line-of-sight direction. Let δx, δy, and δz represent the partial derivatives of the pseudorange, and let δx, δy, and δz represent the positions of the receiver in the x, y, and z directions, respectively. ε' represents the receiver's frequency offset, and ε′ represents the linearization error vector.

4. The method according to claim 1, characterized in that, The constraint parameters are obtained using the following formula: In the formula, A represents the constraint parameter. Here, Hx represents the instantaneous Doppler prediction vector, y represents the instantaneous Doppler frequency shift measurement vector, α represents the regularization parameter greater than 0, Ω(x) represents the stable functional, and R represents the regularization matrix.

5. The method according to claim 1, characterized in that, The instantaneous Doppler localization result based on the chance signal is obtained by the following formula: In the formula, This represents the instantaneous Doppler localization result based on the chance signal, where I represents the identity matrix.

Images