CN114966533A - Direction finding method of phase interferometer of direction finding positioning system - Google Patents
Direction finding method of phase interferometer of direction finding positioning system Download PDFInfo
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Abstract
The invention discloses a direction finding method of a phase interferometer of a direction finding positioning system, which comprises the following steps: the terminal broadcasts a data packet signal with sign information and sine waves according to a protocol; after the base station receives and identifies the mark information, the base station controls the radio frequency switch to receive the sine wave signal in the data packet signal according to a preset sequence time-sharing gating antenna; preprocessing the received signal, eliminating phase difference caused by mismatch of radio frequency channel and receiving and transmitting carrier frequency, and constructing a multi-channel received signal; selecting a base line to calculate a phase difference, selecting a base line group to calculate a sum phase difference and a difference phase difference, and combining a fuzzy phase combination to construct a plurality of groups of complex numbers containing arrival angle information; filtering complex elements with low clustering degree by a clustering method and calculating all possible arrival angles; and finally, obtaining an estimated value of the arrival angle of the signal by an energy method. The method can enable the base station to quickly and accurately estimate the arrival angle of the terminal broadcast signal, and has lower complexity and cost.
Description
Technical Field
The invention relates to the technical field of radio signal direction finding, in particular to a direction finding method of a phase interferometer of a direction finding positioning system.
Background
The radio direction finding aims at detecting the incoming wave direction of a radiation source, and has wide application in military and civil fields, such as electronic reconnaissance, radar, secondary radar, mobile communication, indoor positioning and the like. Compared with other direction finding methods, the phase interferometer direction finding method has the advantages of simple structure and easiness in implementation. Compared with other array types, the circular array has higher utilization rate of the space of the array surface in two-dimensional direction finding. In most cases, a uniform circular array is generally used.
The invention reduces the base station cost and reduces the data amount by optimizing the base station antenna array design and adopting the time division mode to design the antenna channel gating sequence of a single receiving processor, but simultaneously changes the received signal model to cause the phase interferometer direction finding algorithm to be unusable, therefore, the received signal model is reconstructed according to the antenna channel gating sequence design and the interferometer direction finding algorithms under different array element numbers, different base line lengths and different phase difference combinations are deduced, and the clustering method and the energy method are fused for deblurring to obtain the estimated value of the incident angle of the terminal. The invention can enable the base station to quickly and accurately estimate the arrival angle of the terminal broadcast signal, and has lower complexity and cost.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a direction finding method of a phase interferometer of a direction finding positioning system, which can enable a base station to quickly and accurately estimate the arrival angle of a terminal broadcast signal and has the technical characteristic of low complexity.
In order to achieve the above purpose, the technical solution for solving the technical problem is as follows:
a direction finding method of a phase interferometer of a direction finding positioning system comprises the following steps:
step S1: a terminal broadcasts a data packet signal with mark information, wherein the data packet signal comprises a section of continuous sine wave signal for direction finding;
step S2: after the central communication antenna of the base station receives and identifies the mark information, the base station controls the radio frequency switch to time-share gate the direction-finding antenna and the communication antenna according to a preset sequence to receive the sine wave signal in the data packet signal;
step S3: preprocessing a received signal, eliminating phase difference of a radio frequency channel and phase difference caused by receiving and transmitting carrier frequency mismatch, and constructing a multi-channel received signal;
step S4: selecting direction-finding array elements with mutual interval p to form a base line and calculating phase difference, selecting base lines with mutual interval q and calculating sum phase difference and difference phase difference, and combining fuzzy phase combination to construct a plurality of groups of complex numbers { f i pq }；
Step S5: analyzing the clustering degree of each element in a group of complex numbers and other groups of elements by a clustering method, filtering the elements with lower clustering degree or module value greater than 1, and calculating all possible arrival angles by using the remaining elements;
step S6: and for each possible arrival angle, generating a guide vector by using the position of the array element, the wavelength and the radius information of the circular array, combining the vector generated signal s consisting of the signals received by each antenna, calculating the signal energy, and taking the angle with the strongest energy as an estimated value.
Further, the step S1 includes the following steps:
step S11: the mark information at least comprises a MAC address for identifying and distinguishing the terminal and a characteristic identification code for identifying a sine wave;
step S12: the sine wave signal s (t) is generated by modulating direction-finding information code with frequency f sin I.e. s (t) exp { j2 pi f sin t}。
Further, the step S2 includes the following steps:
step S21: the base station comprises an array antenna, the array antenna consists of a communication antenna array element and N direction-finding antenna array elements, the direction-finding antennas are uniformly distributed along a circumference with the radius of R, the array elements are spaced by a radian omega of 2 pi/N and numbered 1,2,.
Step S22: the radio frequency switch gates the communication antenna to receive the space radio signal;
step S23: when the characteristic identification code for identifying the sine wave is detected, the base station controls the radio frequency switch to time-divisionally gate the direction-finding antenna and the communication antenna according to a preset sequence to receive the sine wave signal;
step S24: the preset array element gating sequence is that the communication antenna array elements, the direction-finding antenna array elements, the communication antenna array elements and the direction-finding antenna array elements are alternately gated, and optionally, the communication antenna array elements are gated by circulating several rounds;
step S25: gating duration T sw And 2f sin T sw Is an integer;
step S26: the receiving wavelength of the gating array element is lambda and is determined by the pitch angle theta and the azimuth angle of the antenna array
When the sine wave signal s (T) of the direction exists, s (T-2T) sw )＝exp{j(2πf sin t-2π·2f sin T sw )}＝exp{j2πf sin t}＝s(t)；
When the communication antenna is gated, i.e., i 0, N0, 2N-2,
y i (t)＝s(t-nT sw )exp{j2πΔf(t-nT sw )}，
when the direction-finding antenna is gated, i.e., i 1,., N1, 3., 2N-1,
wherein, Δ f is the frequency difference caused by the mismatch of the receiving and transmitting carrier frequencies;
step S27: the mismatch of the receiving and transmitting carrier frequencies is generated by the combined action of Doppler frequency offset introduced by the mutual motion between the terminal and the base station and the mismatch of the receiving and transmitting local oscillators.
Further, the step S3 includes the following steps:
step S31: compensating the phase difference of the radio frequency channels, and calibrating the phase difference through a static signal source in the far field normal direction of the antenna array;
step S32: compensating for phase difference caused by mismatch of receiving and transmitting carrier frequencies, and constructing multi-channel received signal r i (t), i ═ 1,2,. ang, N, satisfying:
wherein exp { j γ } is a constant;
step S33: r is i (t) the longer the signal length, the higher the measurement accuracy of the phase difference, and the single measurement, the measurement accuracy of the phase difference and the signal-to-noise ratio have the following relationship:
epsilon is the signal-to-noise ratio, and the precision is improved to
L＝T sw /T s ，T s A sampling time interval.
Further, the step S4 includes the following steps:
step S41: selecting a baseline (i, i + p) and a baseline (i + q, i + q + p), which are not parallel;
the base line (i, i + p) consists of mod (i-1, N) +1 and mod (i + p-1, N) +1 direction-finding antenna elements, and the phase difference is:
step S42: the maximum phase ambiguity number is combined with the wavelength, the size of the antenna array surface and the direction finding range
The fuzzy phase difference is set as phi i,i+p +2M i,i+p π}，
Similarly, the phase difference of the baseline (i + q, i + q + p) is:
step S43: the maximum phase ambiguity number is combined with the wavelength, the size of the antenna array surface and the direction finding range
The fuzzy phase difference is set as phi i+q,i+q+p +2M i+q,i+q+p π}，
The sum of the phase differences between the base line (i, i + p) and the base line (i + q, i + q + p) is:
the difference between the phase difference between the base line (i, i + p) and the base line (i + q, i + q + p) is:
step S44: definition of
Combining the fuzzy phase difference set to construct a set of complex numbers:
n groups of complex numbers are constructed by changing the value of i (i 1, 2.., N).
Further, the step S5 includes the following steps:
step S51: with a certain set of complex numbers f i pq For reference, each element in the group is close to one element in the rest groups, namely the clustering degree of the elements is the highest, the close elements correspond to the real incoming wave direction, the distance from each element in the group to each element in the rest groups is calculated, and if the element modulus is larger than 1, the distance between the elements is set as the maximum value;
step S52: searching the shortest distance from each element in the group to other elements in each group, summing the N-1 shortest distances corresponding to each element, and finding out the element class with the smallest distance sum in the group;
step S53: at least one element class exists in the group, and all possible angles of arrival are calculated from elements in the element class:
further, the step S6 includes the following steps:
step S61: for each possible angle of arrival
Combining the wavelength and the position of the antenna array element to generate an Nx 1 guide vector A;
step S62: eliminating phase difference signal r by using each array element i (t) forming an N × L dimensional data vector R;
step S63: calculating S ═ A H R, obtaining a 1 xL-dimensional data vector S and obtaining the element energy sum P thereof, namely P ═ Σ | S i | 2 ，s i Is the ith element in the data vector S;
step S64: each possible angle of arrival corresponds to an energy, and the angle corresponding to the maximum energy is used as an unambiguous angle of arrival estimate.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages and positive effects:
the direction finding method of the phase interferometer of the direction finding positioning system can enable a base station to quickly and accurately estimate the arrival angle of the terminal broadcast signal, and has the technical characteristic of low complexity.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:
FIG. 1 is a schematic flow chart of a direction-finding method of a phase interferometer of a direction-finding positioning system according to the present invention;
fig. 2 is a schematic diagram of an antenna array according to the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, the present embodiment discloses a direction finding method for a phase interferometer of a direction finding positioning system, which includes the following steps:
step S1: a terminal broadcasts a data packet signal with mark information, wherein the data packet signal comprises a section of continuous sine wave signal for direction finding;
step S2: after the central communication antenna of the base station receives and identifies the mark information, the base station controls the radio frequency switch to time-share gate the direction-finding antenna and the communication antenna according to a preset sequence to receive the sine wave signal in the data packet signal;
step S3: preprocessing a received signal, eliminating phase difference of a radio frequency channel and phase difference caused by receiving and transmitting carrier frequency mismatch, and constructing a multi-channel received signal;
step S4: selecting p-spaced direction-finding array elements to form a base line and calculating phase difference, selecting q-spaced base lines and calculating sum phase difference and difference phase difference, and combining fuzzy phase combination to construct a plurality of complex numbers { f } i pq }；
Step S5: analyzing the clustering degree of each element in a group of complex numbers and other groups of elements by a clustering method, filtering the elements with lower clustering degree or module value greater than 1, and calculating all possible arrival angles by using the remaining elements;
step S6: for each possible arrival angle, information such as array element position, wavelength, circular array radius and the like is used for generating a guide vector, a signal s is generated by combining vectors formed by signals received by each antenna, signal energy is calculated, and the angle with the strongest energy is taken as an estimated value.
Further, the step S1 includes the following steps:
step S11: the mark information at least comprises a MAC address for identifying and distinguishing the terminal and a characteristic identification code for identifying a sine wave;
step S12: the sine wave signal s (t) is generated by modulating direction-finding information code with frequency f sin I.e. s (t) exp { j2 pi f sin t}。
Further, the step S2 includes the following steps:
step S21: the base station comprises an array antenna, the array antenna consists of a communication antenna array element and N direction-finding antenna array elements, the direction-finding antennas are uniformly distributed along a circumference with the radius of R, the array elements are spaced by a radian omega of 2 pi/N and numbered 1,2,.
Step S22: the radio frequency switch gates the communication antenna to receive the space radio signal;
step S23: when the characteristic identification code for identifying the sine wave is detected, the base station controls the radio frequency switch to time-divisionally gate the direction-finding antenna and the communication antenna according to a preset sequence to receive the sine wave signal;
step S24: the preset array element gating sequence is that the communication antenna array elements, the direction-finding antenna array elements, the communication antenna array elements and the direction-finding antenna array elements are alternately gated, and optionally, the communication antenna array elements are gated by circulating several rounds;
step S25: gating duration T sw And 2f sin T sw Is an integer;
step S26: the receiving wavelength of the gating array element is lambda and is determined by the pitch angle theta and the azimuth angle of the antenna array
When the sine wave signal s (T) of the direction exists, s (T-2T) sw )＝exp{j(2πf sin t-2π·2f sin T sw )}＝exp{j2πf sin t}＝s(t)；
When the communication antenna is gated, i.e., i 0, N0, 2N-2,
y i (t)＝s(t-nT sw )exp{j2πΔf(t-nT sw )}，
when the direction-finding antenna is gated, i.e., i 1,., N1, 3., 2N-1,
wherein, Δ f is the frequency difference caused by the mismatch of the receiving and transmitting carrier frequencies;
step S27: the mismatch of the receiving and transmitting carrier frequencies is generated by the combined action of Doppler frequency offset introduced by the mutual motion between the terminal and the base station and the mismatch of the receiving and transmitting local oscillators.
Further, the step S3 includes the following steps:
step S31: compensating the phase difference of the radio frequency channel, wherein the phase difference is calibrated by a static signal source in the far field normal direction of the antenna array, and the analyzed phase difference is caused by the mismatch of the radio frequency channel, components and a receiving and transmitting carrier frequency because the phase difference introduced by an incident angle does not exist in the received signals of each antenna at the moment;
step S32: compensating for phase difference caused by mismatch of receiving and transmitting carrier frequencies, and constructing multi-channel received signal r i (t), i ═ 1,2,. ang, N, satisfying:
wherein exp { j γ } is a constant;
step S33: r is i (t) the longer the signal length, the higher the measurement accuracy of the phase difference, and the single measurement, the measurement accuracy of the phase difference and the signal-to-noise ratio have the following relationship:
epsilon is the signal-to-noise ratio, and the precision is improved to
L＝T sw /T s ，T s A sampling time interval.
Further, the step S4 includes the following steps:
step S41: selecting a baseline (i, i + p) and a baseline (i + q, i + q + p), which are not parallel;
the base line (i, i + p) consists of mod (i-1, N) +1 and mod (i + p-1, N) +1 direction-finding antenna elements, and the phase difference is:
step S42: the maximum phase ambiguity number is combined with the wavelength, the size of the antenna array surface and the direction finding range
The fuzzy phase difference is set as phi i,i+p +2M i,i+p π}，
Similarly, the phase difference of the baseline (i + q, i + q + p) is:
step S43: the maximum phase ambiguity number of the combination of wavelength, antenna array plane size and direction finding range is
The fuzzy phase difference is set as phi i+q,i+q+p +2M i+q,i+q+p π}，
The sum of the phase differences between the base line (i, i + p) and the base line (i + q, i + q + p) is:
the difference between the phase difference between the base line (i, i + p) and the base line (i + q, i + q + p) is:
step S44: definition of
Combining the fuzzy phase difference set to construct a set of complex numbers:
n groups of complex numbers are constructed by changing the value of i (i 1, 2.., N).
Further, the step S5 includes the following steps:
step S51: with a certain set of complex numbers f i pq For reference, each element in the group is close to one element in the rest groups, namely the clustering degree of the elements is the highest, the close elements correspond to the real incoming wave direction, the distance from each element in the group to each element in the rest groups is calculated, and if the element modulus is larger than 1, the distance between the elements is set as the maximum value;
step S52: searching the shortest distance from each element in the group to other elements in each group, summing the N-1 shortest distances corresponding to each element, and finding out the element class with the smallest distance sum in the group;
step S53: at least one element class exists in the group, and all possible arrival angles are calculated according to elements in the element class:
further, the step S6 includes the following steps:
step S61: for each possible angle of arrival
Combining the wavelength and the position of the antenna array element to generate an Nx 1 guide vector A;
step S62: eliminating phase difference signal r by using each array element i (t) forming an N × L dimensional data vector R;
step S63: calculating S ═ A H R, obtaining a 1 XL-dimensional data vector S and obtaining the element energy sum P thereof, namely P ═ Σ | S i | 2 ，s i Is the ith element in the data vector S;
step S64: each possible angle of arrival corresponds to an energy, and the angle corresponding to the maximum energy is used as an unambiguous angle of arrival estimate.
Example (b):
the terminal adopts the data packet signal of bluetooth communication protocol broadcast area sign information, and the data packet signal contains a section of continuous sine wave signal and is used for the direction finding, contains the following information in the data packet:
byte numbers 7-12 represent MAC addresses for identifying and distinguishing terminals;
byte numbers 15-17 represent characteristic identification codes for identifying sine waves;
byte numbers 27-43 represent direction-finding information codes, for example, a CH37 broadcast channel is adopted, the signal bandwidth is 1MHz, and the direction-finding information codes are as follows: 0xCC, 0x27, 0x45, 0x67, 0xF7, 0xDB, 0x34, 0xC4, 0x03, 0x8E, 0x5C, 0x0B, 0xAA, 0x97, 0x30, 0x56, 0xE6, the signal generated after CH37 channel whitening filtering and GFSK modulation is a sine wave of 250kHz, namely f 37 sin ＝250kHz。
The base station comprises an array antenna, the array antenna consists of a communication antenna array element and 6 direction-finding antenna array elements, the antenna array is shown in figure 2, the direction-finding antennas are uniformly distributed along the circumference with the radius of R ═ lambda/2, the array elements are spaced by the radian of omega ═ pi/3, and are numbered with 1, 2.
The pitch angle is defined as the included angle between the incident direction of the signal and the XOY plane, and the azimuth angle is defined as the included angle between the projection of the incident direction of the signal on the XOY plane and the X axis.
When the characteristic identification code for identifying the sine wave is detected, the base station controls the radio frequency switch to time-share gate the direction-finding antenna and the communication antenna to receive the sine wave signal according to a preset sequence, the preset gating sequence of the array elements is 0, 1, 0,2, 0, 3, … …, 0, 6, and the gating duration T sw ＝2μs，2f sin T sw ＝1；
Receiving wavelength is lambda and is formed by the pitch angle theta and azimuth angle of the antenna array
Directional sine wave signal s (t) is generated when the communication antenna is gated, i.e., i is 0, N is 0, 2N-2,
y i (t)＝s(t-nT sw )exp{j2πΔf(t-nT sw )}，
when the direction-finding antenna is gated, i.e., i 1,., N1, 3., 2N-1,
wherein, Δ f is the frequency difference caused by the mismatch of the transmitting and receiving carrier frequencies.
Compensating the phase difference of the radio frequency channels, wherein the phase difference is calibrated through a static signal source in the far field normal direction of the antenna array, and because the phase difference introduced by an incident angle does not exist in signals received by each antenna at the moment, the phase difference is caused by mismatching of the radio frequency channels, components and local oscillators for receiving and transmitting;
compensating for phase difference caused by mismatch of receiving and transmitting carrier frequencies, and constructing multi-channel received signal r i (t), i ═ 1,2,. and N, satisfy
Wherein exp { j γ } is a constant;
sampling time interval T s ＝0.25μs，r i (t) the signal length is L-8, and the phase difference is measured with a precision of
ε is the signal-to-noise ratio.
Setting p to be 3 and q to be 1;
the base line (i, i +3) is not parallel to the base line (i +1, i + 4);
the base line (i, i +3) consists of mod (i-1,6) +1 antenna elements and mod (i +3-1,6) +1 antenna elements, and the phase difference is:
the maximum phase ambiguity number is combined with the wavelength, the size of the antenna array surface and the direction finding range
Blurred phaseThe set of bit differences is { phi i,i+3 +2M i,i+3 π}，M i,i+3 ∈[-1,1]；
Similarly, the phase difference of the baseline (i +1, i +4) is:
the maximum phase ambiguity number is combined with the wavelength, the size of the antenna array surface and the direction finding range
The fuzzy phase difference is set as phi i+1,i+4 +2M i+1,i+4 π}，M i+1,i+4 ∈[-1,1]；
The sum of the phase differences between the baseline (i, i +3) and the baseline (i +1, i +4) is:
the difference between the phase difference of the base line (i, i +3) and the base line (i +1, i +4) is:
definition of
Combining the fuzzy phase difference set to construct a set of complex numbers:
by changing the value of i (i ═ 1, 2.., 6), 6 sets of complex numbers are constructed.
With a first plurality f 1 pq For reference, each element in the group is close to one element in the rest groups, namely the clustering degree of the elements is the highest, the close elements correspond to the real incoming wave direction, the distance from each element in the group to each element in the rest groups is calculated, and if the element modulus is larger than 1, the distance between the elements is set as the maximum value;
searching the shortest distance from each element in the group to other elements in each group, and summing the 5 shortest distances corresponding to each element to find out the element class with the minimum distance sum in the group;
at least one element class exists in the group, and all possible angles of arrival are calculated from elements in the element class:
for each possible angle of arrival
Combining the wavelength and the position of the antenna array element to generate a 6 multiplied by 1 guide vector A;
forming a 6 multiplied by 8 dimensional data vector R by using signals of each array element after eliminating the phase difference of the radio frequency channels;
calculating S ═ A H R, obtaining a data vector S with 1 × 8 dimensions, and obtaining the element energy sum P, namely P ═ Σ | S i | 2 ，s i Is the ith element in the data vector S;
each possible angle of arrival corresponds to an energy, and the angle corresponding to the maximum energy is used as an unambiguous angle of arrival estimate.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (7)
1. A direction finding method of a phase interferometer of a direction finding positioning system is characterized by comprising the following steps:
step S1: a terminal broadcasts a data packet signal with mark information, wherein the data packet signal comprises a section of continuous sine wave signal for direction finding;
step S2: after the central communication antenna of the base station receives and identifies the mark information, the base station controls the radio frequency switch to time-share gate the direction-finding antenna and the communication antenna according to a preset sequence to receive the sine wave signal in the data packet signal;
step S3: preprocessing a received signal, eliminating phase difference of a radio frequency channel and phase difference caused by receiving and transmitting carrier frequency mismatch, and constructing a multi-channel received signal;
step S4: selecting direction-finding array elements with mutual interval p to form a base line and calculating phase difference, selecting base lines with mutual interval q and calculating sum phase difference and difference phase difference, and combining fuzzy phase combination to construct a plurality of groups of complex numbers { f i pq }；
Step S5: analyzing the clustering degree of each element in a group of complex numbers and other groups of elements by a clustering method, filtering the elements with lower clustering degree or module value greater than 1, and calculating all possible arrival angles by using the remaining elements;
step S6: and for each possible arrival angle, generating a guide vector by using the position of the array element, the wavelength and the radius information of the circular array, combining the vector generated signal s consisting of the signals received by each antenna, calculating the signal energy, and taking the angle with the strongest energy as an estimated value.
2. The method of claim 1, wherein the step S1 comprises the following steps:
step S11: the mark information at least comprises a MAC address for identifying and distinguishing the terminal and a characteristic identification code for identifying a sine wave;
step S12: the sine wave signal s (t) is generated by modulating direction-finding information code with frequency f sin I.e. bys(t)＝exp{j2πf sin t}。
3. The method of claim 1, wherein the step S2 comprises the following steps:
step S21: the base station comprises an array antenna, the array antenna consists of a communication antenna array element and N direction-finding antenna array elements, the direction-finding antennas are uniformly distributed along a circumference with the radius of R, the interval radian omega of the array elements is 2 pi/N, the array elements are numbered 1,2, the.
Step S22: the radio frequency switch gates the communication antenna to receive the space radio signal;
step S23: when the characteristic identification code for identifying the sine wave is detected, the base station controls the radio frequency switch to time-divisionally gate the direction-finding antenna and the communication antenna according to a preset sequence to receive the sine wave signal;
step S24: the preset array element gating sequence is that the communication antenna array elements, the direction-finding antenna array elements, the communication antenna array elements and the direction-finding antenna array elements are alternately gated, and optionally, the communication antenna array elements are gated by circulating several rounds;
step S25: gating duration T sw And 2f are sin T sw Is an integer;
step S26: the receiving wavelength of the gating array element is lambda and is determined by the pitch angle theta and the azimuth angle of the antenna array
When the sine wave signal s (T) of the direction exists, s (T-2T) sw )＝exp{j(2πf sin t-2π·2f sin T sw )}＝exp{j2πf sin t}＝s(t)；
When the communication antenna is gated, i.e., i 0, N0, 2N-2,
y i (t)＝s(t-nT sw )exp{j2πΔf(t-nT sw )}，
when the direction-finding antenna is gated, i.e., i 1,., N1, 3., 2N-1,
wherein, Δ f is the frequency difference caused by the mismatch of the receiving and transmitting carrier frequencies;
step S27: the mismatch of the receiving and transmitting carrier frequencies is generated by the combined action of Doppler frequency offset introduced by the mutual motion between the terminal and the base station and the mismatch of the receiving and transmitting local oscillators.
4. The method of claim 1, wherein the step S3 comprises the following steps:
step S31: compensating the phase difference of the radio frequency channels, and calibrating the phase difference through a static signal source in the far field normal direction of the antenna array;
step S32: compensating for phase difference caused by mismatch of receiving and transmitting carrier frequencies, and constructing multi-channel received signal r i (t), i ═ 1, 2.., N, satisfying:
wherein exp { j γ } is a constant;
step S33: r is i (t) the longer the signal length, the higher the measurement accuracy of the phase difference, and the single measurement, the measurement accuracy of the phase difference and the signal-to-noise ratio have the following relationship:
epsilon is the signal-to-noise ratio, and the precision is improved to
L＝T sw /T s ，T s A sampling time interval.
5. The method of claim 1, wherein the step S4 comprises the following steps:
step S41: selecting a baseline (i, i + p) and a baseline (i + q, i + q + p), which are not parallel;
the base line (i, i + p) consists of mod (i-1, N) +1 and mod (i + p-1, N) +1 direction-finding antenna elements, and the phase difference is:
step S42: the maximum phase ambiguity number is combined with the wavelength, the size of the antenna array surface and the direction finding range
Set of fuzzy phase differences as
Similarly, the phase difference of the baseline (i + q, i + q + p) is:
step S43: the maximum phase ambiguity number is combined with the wavelength, the size of the antenna array surface and the direction finding range
The fuzzy phase difference is set as phi i+q,i+q+p +2M i+q,i+q+p π}，
The sum of the phase differences between the base line (i, i + p) and the base line (i + q, i + q + p) is:
the difference between the phase difference between the base line (i, i + p) and the base line (i + q, i + q + p) is:
step S44: definition of
Combining the fuzzy phase difference set to construct a set of complex numbers:
n groups of complex numbers are constructed by changing the value of i (i 1, 2.., N).
6. The method of claim 1, wherein the step S5 comprises the following steps:
step S51: with a certain set of complex numbers f i pq For reference, each element in the group is close to one element in the rest groups, namely the clustering degree of the elements is the highest, the close elements correspond to the real incoming wave direction, the distance from each element in the group to each element in the rest groups is calculated, and if the element modulus is larger than 1, the distance between the elements is set as the maximum value;
step S52: searching the shortest distance from each element in the group to other elements in each group, summing the N-1 shortest distances corresponding to each element, and finding out the element class with the smallest distance sum in the group;
step S53: at least one element class exists in the group, and all possible angles of arrival are calculated from elements in the element class:
7. the method of claim 1, wherein the step S6 comprises the following steps:
step S61: for each possible angle of arrival
Combining the wavelength and the position of the antenna array element to generate an Nx 1 guide vector A;
step S62: eliminating phase difference signal r by using each array element i (t) forming an N × L dimensional data vector R;
step S63: calculating S ═ A H R, obtaining a 1 XL-dimensional data vector S and obtaining the element energy sum P thereof, namely P ═ Σ | S i | 2 ，s i Is the ith element in the data vector S;
step S64: each possible angle of arrival corresponds to an energy, and the angle corresponding to the largest energy is used as an unambiguous angle of arrival estimate.
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