CN109425875B - Satellite signal separation and processing device and method - Google Patents

Abstract

The present application provides a satellite signal separation and processing device and method. The satellite signal separation and processing device includes: an antenna array; and a processor, wherein the antenna array includes a plurality of array elements, and the processor adjusts the shape of the composite pattern of the plurality of array elements, and when the satellite signal to be separated is to be separated The incoming and outgoing directions form a pointing gain and at the same time form attenuation in the incoming and outgoing directions of other satellite signals, so as to separate the satellite signals to be separated. The number of required antenna array elements is greatly reduced, and the size and cost of the antenna array are greatly reduced.

Description

Satellite signal separation and processing device and method

technical field

The present application relates to a satellite signal separation processing device and method.

Background technique

As the global navigation satellite system (GNSS) has been widely used in the military and civilian fields, the research on the navigation countermeasures around the GNSS system has also received increasing attention.

In a complex transponder-type spoofing jamming scenario, it is necessary to separate the received satellite signals, thereby introducing a set delay and Doppler to each satellite signal. In this way, the target can be interfered with the designated position, which has higher concealment and controllability than direct forwarding without signal separation.

Disclosed civil signals can be signal separated based on pseudocode. But for the unknown pseudo-random code authorization signal, there are mainly two spatial processing methods for signal separation. The first method utilizes multiple parabolic antennas, each of which points and tracks a satellite to be separated by adjusting its azimuth and elevation angles. The second method is to use an antenna array to form a gain beam aimed at the satellite to be separated. In the prior art, these two satellite signal separation methods only consider the information of the incoming direction of the satellite signal to be separated, so, in order to achieve sufficient spatial resolution, the main lobe width of the antenna and the main beam of the array need to be narrow enough to meet the The requirement of spatial resolution means larger antenna aperture and larger number of array elements. A set of parabolic antennas with a diameter of 3m is usually required to separate multiple navigation satellite signals. In order to achieve the same spatial resolution, a half-wavelength planar antenna array requires at least hundreds of array elements. Both methods have high hardware cost and implementation complexity.

SUMMARY OF THE INVENTION

The purpose of the present application is to provide a satellite signal separation and processing device and method with low hardware cost and simple implementation.

According to an aspect of the present application, a satellite signal separation and processing device is provided, comprising: an antenna array; and a processor, wherein the antenna array includes a plurality of array elements, and the processor adjusts the The shape of the composite pattern forms a pointing gain in the incoming direction of the satellite signal to be separated and attenuation in the incoming direction of other satellite signals.

According to an aspect of the present application, a satellite signal separation and processing method is provided, comprising: receiving satellite signals from multiple satellites through an antenna array including multiple array elements, and adjusting the shape of a composite pattern of the multiple array elements , forming a pointing gain in the incoming direction of the satellite signal to be separated while forming attenuation in the incoming direction of other satellite signals.

According to the embodiment of the present application, when satellite signal separation is performed, the direction information of all satellite signals is considered, and the steering vectors of the antenna array for all satellites are used to calculate the weighted vector of the antenna array for the satellite signals to be separated. Separating the incoming direction of the satellite signal forms a directional gain while forming attenuation in the incoming direction of other satellite signals, so as to separate the satellite signal to be separated, the required number of antenna elements is greatly reduced, and the size and cost of the antenna array are greatly reduced.

Description of drawings

FIG. 1 shows an apparatus for separating and processing satellite signals according to an embodiment of the present application.

FIG. 2 shows a satellite signal separation and processing apparatus according to another embodiment of the present application.

FIG. 3 shows a schematic diagram of an array element arrangement of an antenna array and a satellite signal direction according to an embodiment of the present application.

FIG. 4 shows a schematic diagram of the shape of a composite pattern of multiple array elements obtained by a method for separating and processing satellite signals according to an embodiment of the present application.

Detailed ways

The apparatus and method for separating and processing satellite signals based on an antenna array disclosed in the present application will be described in detail below with reference to the accompanying drawings. For the sake of brevity, in the description of the various embodiments of the present application, the same or similar devices use the same or similar reference numerals.

The following first takes the GPS satellite navigation system as an example to analyze the spatial distribution characteristics of satellites from the angle of the number of visible satellites and the angle between the satellites.

According to the GPS baseline configuration, the GPS constellation consists of 24 working satellites located in 6 geocentric orbital planes, each with 4 satellites. Sufficiently dispersed satellite geometry ensures good observability for global users. At any point on the Earth's surface, the number of visible satellites varies from a minimum of 4 to a maximum of 11. Also, usually the minimum angle between satellites is not less than 10, and in most cases the angle between satellites is greater than 20 degrees.

According to the above analysis of satellite spatial distribution, it can be seen that an effective signal separation method should be able to extract any given satellite signal from at most 11 received satellite signals with a minimum angle of 10°. Considering the sensitivity range of general GPS receivers, the attenuation of other satellite signals should not be less than 20dB to 30dB. The current satellite signal separation method in the prior art only considers the information of the incoming direction of the satellite signal to be separated. In this way, the number of antenna array elements required for signal separation depends on the spatial resolution of the antenna array, which must be formed by a large number of antenna array elements. A very narrow beam can effectively attenuate the signals of other satellites. According to the relationship between the main lobe width of the uniform linear array beam pattern and the number of array elements, in order to achieve a main lobe width of 10°, at least 12 antenna array elements are usually required. If two-dimensional beam scanning is performed on the azimuth and elevation angles of the satellite signal, a plane array needs to be used. Generally, the pattern function of a rectangular array is the product of two linear array pattern functions, that is, to achieve 10° At least 12×12 antenna elements are required for the spatial resolution.

According to an embodiment of the present application, a satellite signal separation and processing device and method are proposed, which receive satellite signals from multiple satellites through an antenna array including multiple array elements, and adjust the shape of a composite pattern of multiple array elements. , forming a pointing gain in the incoming direction of the satellite signal to be separated while forming attenuation in the incoming direction of other satellite signals. In this way, the information of the incoming and outgoing signals of all satellites is utilized, and the required number of elements of the antenna array depends on the number of satellites to be separated, not on the spatial resolution.

FIG. 1 shows an apparatus for separating and processing satellite signals according to an embodiment of the present application. As shown in FIG. 1 , the satellite signal separation and processing apparatus 10 includes an antenna array 100 and a processor 200 . The antenna array 100 can receive satellite signals from M (M>1) satellites, and the antenna array 100 further includes N (N>1) array elements 110 . The processor 200 can adjust the composite pattern shape of the multiple array elements 110 of the antenna array 100 to form a directional gain in the incoming direction of the satellite signal to be separated while forming attenuation in the incoming direction of other satellite signals, thereby separating the satellite signal to be separated.

Any one of the satellite signals can be selected as the satellite signal to be separated. In this way, the M satellite signals can be separated one by one in the above manner only through the antenna array having M antenna elements. Of course, in order to achieve a more suitable antenna array arrangement in engineering applications, the number of antenna array elements may also be greater than M, for example, M+1, M+2 or M+3 antenna array elements may be used. In this way, the size and cost of the antenna array will be greatly reduced.

FIG. 2 shows a satellite signal separation and processing apparatus according to another embodiment of the present application. As shown in FIG. 2 , the processor 200 includes a determination module 210 and a calculation module 220 . The determination module 210 determines the steering vector of the antenna array for each satellite. The calculation module 220 calculates the weighted vector of the antenna array for the satellite to be separated according to the steering vector of the antenna array for each satellite, so as to adjust the shape of the composite pattern of the multiple elements of the antenna array.

According to an embodiment of the present application, M satellite signals are separated by an antenna array with N array elements, and the signal model received by the array can be expressed as:

in,

x(t) is the N×1-dimensional observation data vector, and each row corresponds to the signal received by one array element;

s _j (t) represents the jth satellite signal;

a _j (j=1,...M) represents the steering vector of the antenna array for the jth satellite signal, which is related to the geometric configuration of the antenna array and the incoming wave direction of the satellite signal;

n(t) is an N×1-dimensional noise signal vector, and each row corresponds to the additive white Gaussian noise at its corresponding array element.

By constructing a weighting vector for the antenna array to weight and sum the received signals of each array element, the gain of the antenna array for signals in different directions can be controlled, that is, the composite pattern shape of multiple array elements. The output signal of the array can be expressed as:

In order to realize the separation of satellite signals, using the information of the incoming directions of all satellite signals, a weighting vector is constructed for the satellites to be separated to weight and sum the received signals of the array, so that a pointing gain is formed in the incoming directions of the satellite signals to be separated while the incoming directions of other satellite signals are Attenuation is formed to separate the satellite signal to be separated.

Without loss of generality, assuming that the satellite with j=1 is used as the satellite signal to be separated, the received signal can be expressed as:

For the satellite to be separated j=1, the output signal of the array when the weighting vector is w is:

According to this embodiment, the processor 200 determines the steering vector a _j of the antenna array for each satellite, and calculates the weighting vector w of multiple elements of the antenna array according to the steering vector a _j of the antenna array for each satellite , so that in the output signal, a pointing gain is formed in the coming direction of the satellite signal s ₁ (t) to be separated, while attenuation is formed in the coming direction of the other satellite signals s _j (t). In this way, the output signal will contain only the satellite signal to be separated, while the other satellite signals have been attenuated into noise components.

According to an embodiment of the present application, the determination module 210 of the processor 200 may determine the steering vector a _j of the antenna array for each satellite based on the array synthesis method.

For a given satellite, its steering vector is related to the arrival direction of the satellite signal, the attitude and geometry of the array, the non-ideality of the antenna element and the radio frequency channel and other factors. After the antenna array is calibrated, the non-idealities of the antenna elements and the RF channel can be ignored, and the steering vector can be calculated from the relative positions of the satellite and the array.

FIG. 3 shows a schematic diagram of an array element arrangement of an antenna array of an apparatus for separating and processing satellite signals and a direction of satellite signals according to an embodiment of the present application. Suppose the incident direction vector of a satellite signal is:

表示与X轴间的方位角。对一般的接收机来说，可见卫星的方向是在ENU本地坐标系上定义的，在天线阵列姿态已知的情况下，入射方向天线坐标系中的坐标可以由ENU坐标系中的坐标乘以一个旋转矩阵计算得到。where θ represents the elevation angle of the direction vector on the XY plane where the array is located,

Indicates the azimuth angle from the X-axis. For a general receiver, the direction of the visible satellite is defined in the ENU local coordinate system. When the attitude of the antenna array is known, the coordinates in the incident direction antenna coordinate system can be multiplied by the coordinates in the ENU coordinate system. A rotation matrix is calculated.

The geometry of the array, that is, the arrangement of the antenna elements, can be represented by a matrix:

P=[p ₁ ,p ₂ ,...p _N ] ^T ,

Among them, N is the number of array elements, and p _k =[x _k , y _k , z _k ] ^T represents the position of the kth array element in the antenna coordinate system.

Then the steering vector a _j of the antenna array for each satellite can be expressed as:

where _λ represents the wavelength of the carrier signal of the satellite signal,

表示第j颗卫星信号的入射方向向量。

Represents the incident direction vector of the jth satellite signal.

According to an embodiment of the present application, the determination module 210 of the processor 200 may further determine the steering vector a _j of the antenna array for each satellite based on the signal tracking method. For example, satellite navigation systems usually broadcast both civilian and military signals at the same time, and methods based on signal tracking can track the civilian signal to determine the steering vector of the military signal.

Compared with the method based on array synthesis, the method based on signal tracking does not require a large amount of prior information and complex calibration process. The steering vector a _j of a satellite can be expressed as:

Among them, v _jk , φ _jk respectively represent the amplitude and carrier phase of the j-th satellite signal S extracted from the k-th element channel.

For each visible satellite, the determination module 210 can extract the amplitude and phase of the satellite signal received by each of the N array elements to form a steering vector. This method of steering vector determination requires no prior knowledge of satellite orientation and array geometry, and all non-idealities of the array and RF front-end are included in the extracted magnitude and phase, so this method is self-calibrating , more convenient and effective.

After obtaining the steering vectors a _j of the antenna array, the calculation module 220 of the processor 200 calculates the weighting vector w of the antenna array, and adjusts the shape of the composite pattern of the multiple elements of the antenna array to separate the satellite signals to be separated. come out.

Assuming that each satellite signal is statistically independent and uncorrelated with noise, the power of the output signal y(t) of the antenna array can be expressed as:

Among them, P _j is the power of the jth satellite signal, and P _n is the power of the noise signal.

Calculate the weighting vector w, so that the gain of the satellite signal to be separated increases, for example, the incoming direction of the signal to be separated can have a pointing gain, that is,

w ^H a ₁ =α ₁ =1.

At the same time, when calculating the weighted vector, other satellite signals are regarded as interference, and the attenuation constraint is set upwards.

w ^H a _j =α _j (j=2,...,M).

The attenuation of other satellite signals is made to a predetermined threshold α _j (j=2,...,M). The predetermined threshold can be set according to the receiver sensitivity, for example, the residual signal level after weighted synthesis can be at least lower than the receiver sensitivity.

In addition, it can be seen from the calculation formula of the output signal power that the noise signal power may be amplified by the modulo value of the weighting vector. In order to ensure a specific and sufficient signal-to-noise ratio of the desired signal for the subsequent synthesis of spoofing signals, the construction of the weighting vector should be such that The noise should be as small as possible, that is, the modulo value of the weighting vector should be as small as possible.

Therefore, according to an embodiment of the present application, the signal separation problem is transformed into the following optimization problem based on multilinear constraints:

Among them, w represents the weighting vector of the antenna array for the satellite signal to be separated, a _j (j=1,...,M) represents the steering vector of the antenna array for each satellite, M represents the total number of visible satellites, i represents the satellite to be separated, α _j represents the predetermined threshold of attenuation, min represents the minimization, and st represents the constraint condition.

In this way, according to the embodiments of the present application, when satellite signal separation is performed, the direction information of all satellite signals is considered, and the steering vectors of the antenna array for all satellites are used to calculate the weighted vector of the antenna array for the satellite signals to be separated, The directional gain is formed in the incoming direction of the satellite signal to be separated and the attenuation is formed in the incoming direction of other satellite signals, so as to separate the satellite signal to be separated, the number of required antenna elements is greatly reduced, and the size and cost of the antenna array are greatly reduced.

Without loss of generality, the satellite to be separated can be set i=1. In order to solve the optimal weighted vector, the Lagrangian multiplier method should be used to construct the Lagrangian function:

Then the optimal weight vector w should satisfy:

From the first equation it can be found that the optimal weight vector can be expressed as a linear combination of the steering vectors of the antenna array for each satellite:

Substituting this into the last two constraint equations, λ,μj ( _j =2,...,M) can be solved. It has been proved that the optimal weighting vector can be written in the following form:

w _opt =A(A ^H A) ^-1 b,

in,

A=[a ₁ , a ₂ ,...a _M ], is the array manifold matrix composed of the steering vectors of the antenna array for all satellites;

b=[1,α ₂ ,...α _M ] ^T , which is an M×1-dimensional column vector composed of pointing gain and attenuation coefficient.

In this way, the output signal of the receiver can be expressed as:

The weighted vector of the antenna array for the satellite to be separated can be obtained through the multi-linear constraint optimization calculation based on the above-mentioned satellite gain, so that in the output signal of the antenna array, the gain of the satellite signal to be separated can be guaranteed, and the residual signal of other satellite signals after weighted synthesis can be guaranteed. The signal level is lower than the receiver sensitivity, and the noise is as small as possible, so that the receiver can successfully receive the satellite signal to be separated, while other satellite signals are regarded as interference, thereby realizing the separation of the signal to be separated.

Here, the satellite with j=1 is schematically used as the satellite to be separated. It can be understood that the satellite to be separated can be any one of the visible satellites. Usually, in practical applications, it is necessary to separate all visible satellite signals, solve the above optimization problem for each satellite signal based on the known steering vector information of each satellite, and use the resulting weighted vector to perform the array received signal vector respectively. Weighted synthesis means that all visible satellite signals can be separated one by one.

According to another aspect of the present application, a satellite signal separation and processing method is also proposed, including: receiving satellite signals from multiple satellites through an antenna array including multiple array elements, and adjusting the shape of a composite pattern of multiple array elements , forming a pointing gain in the incoming direction of the satellite signal to be separated while forming attenuation in the incoming direction of other satellite signals. The satellite signal separation processing method further includes: determining a steering vector of the antenna array for each satellite; calculating a weighted vector of the antenna array for the satellite to be separated according to the steering vector of the antenna array for each satellite, The weighting vector adjusts the shape of the composite pattern of the multiple elements of the antenna array, and forms a directivity gain in the incoming direction of the satellite signal to be separated while forming attenuation in the incoming direction of other satellite signals.

According to an embodiment, the number of elements of the antenna array may be determined according to the maximum number of visible satellites. Wherein, the steering vector of the antenna array for each satellite signal may be determined according to the incoming wave directions of the satellite signal to be separated and other satellite signals, and the arrangement of multiple elements of the antenna array. Alternatively, the steering vector of the antenna array for each satellite can be determined by tracking known signals from the satellite to be separated and other satellites, and based on the amplitude and phase of the tracked known signals.

According to an embodiment, according to the obtained steering vector of the antenna array for each satellite signal, the weighted vector of the antenna array for the satellite to be separated is calculated based on the multi-linear constraint optimization of the gain of the satellite signal. Wherein, the multi-linear constraint optimization condition based on the gain of the satellite signal includes: calculating the weighting vector so that the incoming direction of the signal to be separated has a pointing gain, the incoming direction signal of other satellite signals is attenuated to be lower than a predetermined threshold, and the modulo value of the weighting vector is the smallest .

For example, the weighting vector can be calculated based on the following satellite signal gain multilinear constraint optimization:

Among them, w represents the weighting vector of the antenna array for the satellite signal to be separated, a _j (j=1,...,M) represents the steering vector of the antenna array for each satellite, M represents the total number of visible satellites, i represents the satellite to be separated, α _j represents the predetermined threshold of attenuation, min represents the minimization, and st represents the constraint condition.

FIG. 4 shows a schematic diagram of the shape of a composite pattern of multiple array elements obtained by a method for separating and processing satellite signals according to an embodiment of the present application. For ease of illustration, it is assumed here that all visible satellite signals have a fixed pitch angle in the coming direction, and a azimuth angle that varies in [0°, 360°]. After signal separation processing, the shape of the composite pattern of multiple elements of the antenna array is shown in Figure 4. The solid line on the azimuth angle represents the incoming wave direction of the satellite signal to be separated, and the dotted line on the azimuth angle represents other satellites. The direction of the signal. It can be seen that a pointing gain is formed in the incoming direction of the satellite signal to be separated, and attenuation is formed in the incoming direction of other satellite signals, thereby separating the satellite signal to be separated.

The present application proposes an apparatus and method for separating and processing satellite signals based on an antenna array using a known satellite spatial distribution, to separate authorized signals whose pseudocode generation method is unknown. In addition, it can be understood that the satellite signal separation and processing device and method proposed in this application are also applicable to unauthorized signals with known pseudo-code generation methods.

Exemplary embodiments of the present application have been described above with reference to the accompanying drawings. It should be understood by those skilled in the art that the above-mentioned embodiments are only examples for the purpose of illustration, not for limitation. Any modifications, equivalent replacements, etc. made under the teachings of the present application and the protection scope of the claims, etc., All should be included within the scope of protection claimed in this application.

Claims (10)

1. A satellite signal separation processing apparatus comprising:

an antenna array comprising a plurality of array elements; and

a processor, comprising:

a determination module that determines a steering vector for each satellite for the antenna array; and

the calculation module is used for calculating a weighting vector of the antenna array for the satellite to be separated based on satellite signal gain multi-linear constraint optimization according to the steering vector of the antenna array for each satellite, and adjusting the shape of a synthetic directional diagram of a plurality of array elements of the antenna array through the weighting vector, so that the incoming direction of the signal to be separated has directional gain, incoming direction signals of other satellite signals are attenuated to be lower than a preset threshold, and the modulus value of the weighting vector is minimum.

2. The apparatus of claim 1, wherein the number of elements of the antenna array is determined by a maximum number of visible satellites.

3. The apparatus of claim 1, wherein the determining module determines the steering vector of the antenna array for each satellite according to the incoming wave directions of the satellite signal to be separated and other satellite signals and the arrangement of the plurality of elements of the antenna array.

4. The apparatus of claim 1, wherein the determining module tracks known signals from the satellite to be separated and other satellites, and determines the steering vector of the antenna array for each satellite based on the amplitude and phase of the tracked known signals.

5. The apparatus of claim 1, wherein the calculation module calculates the weight vector based on the following satellite signal gain multi-linear constraint optimization:

wherein w represents the weighting vector of the antenna array for the satellite signals to be separated, a_j(j 1.. M) denotes a steering vector of the antenna array for each satellite, M denotes a total number of visible satellites, i denotes a satellite to be separated, and α denotes a total number of satellites to be separated_jRepresents a predetermined threshold for attenuation, min represents minimization, and s.t. represents a constraint.

6. A satellite signal separation processing method, comprising:

receiving satellite signals from a plurality of satellites via an antenna array comprising a plurality of elements, determining a steering vector for the antenna array for each satellite,

and calculating a weighting vector of the antenna array for the satellite to be separated based on satellite signal gain multi-linear constraint optimization according to the steering vector of the antenna array for each satellite, and adjusting the shape of a synthetic directional diagram of a plurality of array elements of the antenna array through the weighting vector, so that the incoming direction of the signal to be separated has directional gain, incoming direction signals of other satellite signals are attenuated to be lower than a preset threshold, and the modulus value of the weighting vector is minimum.

7. The method of claim 6, wherein the number of elements of the antenna array is determined according to the maximum number of visible satellites.

8. The method as claimed in claim 6, wherein the steering vector of the antenna array for each satellite signal is determined according to the incoming wave directions of the satellite signal to be separated and other satellite signals and the arrangement of the plurality of array elements of the antenna array.

9. The method of claim 6, wherein known signals from the satellite to be separated and other satellites are tracked, and a steering vector for each satellite is determined by the antenna array based on the amplitude and phase of the tracked known signals.

10. The method of claim 6, wherein the weight vector is calculated based on the following satellite signal gain multi-linear constraint optimization:

wherein w represents the weighting vector of the antenna array for the satellite signals to be separated, a_j(j 1.. M) denotes a steering vector of the antenna array for each satellite, M denotes a total number of visible satellites, i denotes a satellite to be separated, and α denotes a total number of satellites to be separated_jRepresents a predetermined threshold for attenuation, min represents minimization, and s.t. represents a constraint.

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