CN111220945A - Direction finding method and device and ultra-wideband direction finding system - Google Patents

Direction finding method and device and ultra-wideband direction finding system Download PDF

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CN111220945A
CN111220945A CN201811416573.7A CN201811416573A CN111220945A CN 111220945 A CN111220945 A CN 111220945A CN 201811416573 A CN201811416573 A CN 201811416573A CN 111220945 A CN111220945 A CN 111220945A
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antenna
weight corresponding
incident angle
angles
incident
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赵瑞祥
张西洋
尹作彪
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Qing Yanxun Technology Beijing Co Ltd
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Qing Yanxun Technology Beijing Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0294—Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0284—Relative positioning

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  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
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Abstract

The present disclosure provides a direction finding method, comprising: determining a plurality of incidence angles of a signal sent by a target relative to an antenna array, wherein the incidence angles are included angles of the signal relative to a perpendicular line of a connecting line of two antenna units in the antenna array; and determining the direction of the target according to each incident angle and the first weight corresponding to each incident angle, wherein the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle. By the direction finding method, the direction finding precision of the target direction finding can be improved.

Description

Direction finding method and device and ultra-wideband direction finding system
Technical Field
The disclosure relates to the field of internet of things, in particular to a direction finding method and device and an ultra-wideband direction finding system.
Background
With the development of the internet of things, the position information is more and more important, and the demand for high-precision position information is more and more. Currently, there is a problem of low accuracy in the measurement of the direction information.
Therefore, how to improve the direction finding accuracy when finding the direction of the target becomes a technical problem to be solved by those skilled in the art.
Disclosure of Invention
The embodiment of the disclosure provides a direction finding method, which includes: determining a plurality of incidence angles of a signal sent by a target relative to an antenna array, wherein the incidence angles are included angles of the signal relative to a perpendicular line of a connecting line of two antenna units in the antenna array; and determining the direction of the target according to each incident angle and the first weight corresponding to each incident angle, wherein the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle.
Optionally, the first weight corresponding to the incident angle is negatively correlated with the absolute value of the incident angle, and specifically includes: the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle historical moment; and/or the first weight corresponding to the incident angle is inversely related to the absolute value of the current moment of the incident angle.
Optionally, the number of the antenna units in the antenna array is N, and the number of the incident angles is
Figure BDA0001879616150000011
Wherein N is a positive integer greater than or equal to 3.
Optionally, before determining the direction of the target according to each of the incident angles and the first weight corresponding to each of the incident angles, the method further includes: determining a second weight corresponding to each incident angle, wherein when the distance between two antenna units with opposite incident angles belongs to a first distance interval, the second weight corresponding to the incident angle belongs to the first interval; the determining the direction of the target according to each of the incident angles and the first weight corresponding to each of the incident angles specifically includes determining the direction of the target according to each of the incident angles, the first weight corresponding to each of the incident angles, and the second weight corresponding to each of the incident angles.
Optionally, when the distance between the two antenna elements with the opposite incident angles does not belong to a first distance interval, the second weight corresponding to the incident angle belongs to a second interval, and any value of the first interval is greater than all values of the second interval, where: the first interval is 0.8 to 1 times of the half wavelength of communication.
Optionally, the first weight corresponding to the incident angle is negatively correlated with the absolute value of the incident angle, and specifically includes: when the absolute value of the incidence angle does not belong to a first angle interval, the first weight corresponding to the incidence angle is zero; when the distance between the two antenna units with the opposite incident angles does not belong to the first distance interval, the second weight corresponding to the incident angle belongs to the second interval, which specifically includes: when the distance between the two antenna units with the opposite incident angles does not belong to a first distance interval, the second weight corresponding to the incident angles is zero; the determining the direction of the target according to each of the incident angles, the first weight corresponding to each of the incident angles, and the second weight corresponding to each of the incident angles specifically includes: screening out a credible incident angle of which the first weight corresponding to the incident angle or the second weight corresponding to the incident angle is not zero from all the incident angles; and performing Kalman filtering processing on each credible incidence angle to determine the direction of the target.
Optionally, the trusted angle of incidence includes: θ 1, θ 2, θ 3.. θ m; wherein, at time k, the signal incidence angle comprises: theta 1k、θ2k、θ3k...θmk(ii) a The kalman filtering process performed on each of the trusted incident angles specifically includes: performing extended Kalman filtering processing on each credible incidence angle; wherein the state transition equation in the extended Kalman filtering process is
Figure BDA0001879616150000021
Wherein,
Figure BDA0001879616150000022
a state predictor for a unit vector pointing in the direction of the target at time k,
Figure BDA0001879616150000023
the state optimal estimation value of the unit vector pointing to the direction of the target at the moment k-1; wherein the measurement equation in the extended Kalman filtering process is zk＝h(xk)+vkWherein
Figure BDA0001879616150000024
vkTo measure noise, rkIs a unit vector pointing in the direction of the target at the time k, the
Figure BDA0001879616150000031
Wherein, the1、l2、l3...lmAnd the unit vectors are respectively unit vectors of the connecting line directions of the two antenna units with the corresponding credible incidence angles.
Optionally, the number of the antenna units in the antenna array is specifically 2n, and the number of the incident angles is
Figure BDA0001879616150000032
Wherein n is a positive integer greater than or equal to 2; and (2n-1) antenna units form a polygonal array, and one antenna unit is arranged at the center of the polygonal array, so that connecting lines of any two adjacent antenna units are not parallel.
Optionally, the polygon array is specifically a regular polygon array.
Optionally, a value range of the first weight includes zero, and/or a value of the second interval includes zero.
The embodiment of the present disclosure further provides a direction-finding device, including: the antenna array comprises a processing module, a receiving module and a processing module, wherein the processing module is configured to determine a plurality of incidence angles of a signal sent by a target relative to the antenna array, and the incidence angles are included angles of the signal relative to a perpendicular line of a connecting line of two antenna units in the antenna array; and determining the direction of the target according to each incident angle and a first weight corresponding to each incident angle, wherein the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle.
Optionally, the direction-finding device further includes: an antenna arrangement comprising the antenna array; wherein the number of the antenna units in the antenna array is N, and the number of the incident angles is N
Figure BDA0001879616150000033
Wherein N is a positive integer greater than or equal to 3.
Optionally, the direction-finding device, wherein: the processing module is further configured to determine a second weight corresponding to each incident angle before determining the direction of the target according to each incident angle and a first weight corresponding to each incident angle, wherein the second weight corresponding to each incident angle belongs to a first interval when the distance between two antenna units with opposite incident angles belongs to the first interval; and the number of the first and second groups,
optionally, the processing module is specifically configured to determine the direction of the target according to each of the incident angles, a first weight corresponding to each of the incident angles, and a second weight corresponding to each of the incident angles.
Optionally, the direction-finding device, wherein: the antenna device also comprises a preprocessing module which is respectively connected with each antenna unit; wherein the pre-processing module is configured to determine a phase at which each of the antenna elements receives the signal and provide the phase to the processing module such that the processing module determines each of the angles of incidence.
Optionally, the direction-finding device, wherein: the antenna units in the antenna array are specifically cross omnidirectional antennas.
Optionally, the direction-finding device, wherein: the number of the antenna units in the antenna array is specifically 2n, and the number of the incidence angles is
Figure BDA0001879616150000041
Wherein n is a positive integer greater than or equal to 2; and (2n-1) antenna units form a polygonal array, and one antenna unit is arranged at the center of the polygonal array, so that connecting lines of any two adjacent antenna units are not parallel.
Optionally, the direction-finding device, wherein: the antenna array comprises six antenna units, and the polygonal array is a regular pentagonal array.
Optionally, the direction-finding device, wherein: the first interval is 0.8 to 1 times of the half wavelength of communication.
The embodiment of the present disclosure further provides an ultra wide band direction finding system, including a tag, a base station, and a server, wherein: the tag is configured to transmit an ultra wideband signal to the base station; the base station comprises an antenna device and a preprocessing module; the antenna device comprises an antenna array; the antenna array comprises six antenna units, five antenna units form a regular pentagonal array, and one antenna unit is arranged at the center of the regular pentagonal array; the antenna device is configured to receive the ultra-wideband signal; the preprocessing module is configured to determine phases of the ultra-wideband signals received by the antenna units and provide the phases to the server; the server is configured to determine the direction of the target according to each phase difference, a first weight corresponding to each phase difference and a second weight corresponding to each phase difference; wherein the phase difference is a difference between the two phases; a first weight corresponding to the phase difference is inversely related to an absolute value of the phase difference; and when the distance between the two antenna units belongs to a first distance interval, the second weight corresponding to the phase difference of the ultra-wideband signals received by the two antenna units belongs to the first interval.
The at least one technical scheme adopted by the embodiment of the disclosure can achieve the following beneficial effects that when the direction of the target is determined according to a plurality of incidence angles of the signal sent by the target relative to the antenna array, the incidence angle with larger error is removed or the weight is reduced, the weight of the incidence angle with smaller error is improved, and the direction finding precision can be effectively improved.
Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the disclosure. The objectives and other advantages of the disclosure may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
The technical solution of the present disclosure is further described in detail by the accompanying drawings and examples.
Drawings
The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the principles of the disclosure and not to limit the disclosure. In the drawings:
fig. 1 is a schematic flow chart of a direction finding method provided in an embodiment of the present disclosure.
Fig. 2 is a schematic view of an incident angle in a direction finding method provided by an embodiment of the present disclosure.
Fig. 3 is a schematic diagram of two incident angles in a direction finding method provided by an embodiment of the present disclosure.
Fig. 4 is a schematic flow chart of a direction finding method provided in an embodiment of the present disclosure.
Fig. 5 is a schematic diagram of three incident angles in a direction finding method provided by an embodiment of the present disclosure.
Fig. 6 is a schematic diagram of an antenna array in a direction finding method according to an embodiment of the present disclosure.
Fig. 7 is a schematic diagram of another antenna array in a direction finding method according to an embodiment of the present disclosure.
Fig. 8 is a schematic block diagram of a direction-finding device provided in an embodiment of the present disclosure.
Fig. 9 is a schematic block diagram of a direction-finding device provided in an embodiment of the present disclosure.
Fig. 10 is a schematic structural diagram of an antenna array in a direction-finding device according to an embodiment of the present disclosure.
Fig. 11 is a schematic diagram of a relationship between H and H in a direction-finding device provided in an embodiment of the present disclosure.
Fig. 12 is a schematic structural diagram of another antenna array in a direction-finding device according to an embodiment of the present disclosure.
Fig. 13 is a schematic view of an ultra-wideband direction finding system according to an embodiment of the present disclosure.
Detailed Description
For the purpose of making the purpose, technical solutions and advantages of the present disclosure more clear, the following description will be made on the technical solutions of the present disclosure clearly and completely in conjunction with the specific embodiments of the present disclosure and the corresponding drawings. It is to be understood that the disclosed embodiments are merely exemplary of some, and not necessarily all, of the disclosed embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present specification without any creative effort belong to the protection scope of the present disclosure.
As described above, in order to solve the problem of low direction finding accuracy, according to an embodiment of the present disclosure, there is provided a direction finding method, as shown in fig. 1, the method including:
s101, determining a plurality of incidence angles of a signal sent by a target relative to an antenna array, wherein the incidence angles are included angles of the signal relative to a perpendicular line of a connecting line of two antenna units in the antenna array;
the signal transmitted by the target is specifically a radio frequency signal, such as a bluetooth signal, an ultra wideband signal, and the like.
When the target is far enough away from the antenna array, for example, the distance between the antenna elements in the antenna array is in centimeters, and the distance between the target and the antenna array is several meters or even tens of meters, the signal transmitted by the target can be regarded as a plane wave. As shown in fig. 2, with reference to two antenna elements, the first antenna element 1011 and the second antenna element 1012 are spaced apart by a distance d, so that a signal radiated from a far-field signal source (i.e., a target) can look at a plane wave when reaching the antenna array, and an angle θ between the signal and a perpendicular line connecting the first antenna element 1011 and the second antenna element 1012 is an incident angle.
With reference to FIG. 2, according to
Figure BDA0001879616150000061
determining a value of θ, where α 1 and α 2 are receiving phases of the first antenna unit 1011 and the second antenna unit 1012 for receiving the target transmission signal, d is a distance between the two antenna units, C is a light velocity, ω is a center frequency of the target transmission signal, and pi is a circumferential rate, where α 1 and α 2 may be determined by a radio frequency processing module (e.g., a bluetooth processing module, an ultra wideband processing module), and such a radio frequency processing module capable of determining a phase generally includes a phase-locked loop, a mixer, a digital-to-analog conversion circuit, and other electronic devices, and an internal structure of the radio frequency processing module is not a key point of the present invention and is not described herein.
Referring to fig. 3, the antenna array includes a first antenna element 1011, a second antenna element 1012 and a third antenna element 1013, a target transmits a signal as a plane wave, P1 and P2 are parallel, the target transmits a signal that may generate two incident angles (θ 1 and θ 2 in fig. 3) with respect to three antenna elements in the antenna array, and the direction of the target may be determined according to θ 1 and θ 2. Specifically, in fig. 3, with the position of the first antenna unit 1011 as the starting point of the vector, all vectors having an angle θ 1 with the perpendicular to the first antenna unit 1011 and the second antenna unit 1012 form a conical surface, that is, a conical surface is formed on the right side of the perpendicular to the first antenna unit 1011 and the second antenna unit 1012 in fig. 3, and similarly, all vectors having an angle θ 2 with the perpendicular to the first antenna unit 1011 and the third antenna unit 1013 form another conical surface, and the intersection portion of the two conical surfaces in space is the vector pointing to the target direction. Therefore, when the number of the antenna elements in the antenna array is plural, any two of the antenna elements can generate an incident angle, and the number of the generated incident angles can be known according to the permutation and combination principle. Therefore, when the same signal transmitted by the same target reaches the antenna array, a plurality of incident angles are generated, the value of each incident angle is determined respectively, and the direction of the target is determined according to the values of the plurality of incident angles. The method of determining the angle of incidence from the Phase difference to determine the target direction in the embodiments of the present disclosure is also called Phase difference of arrival (PDOA).
S102, determining the direction of the target according to each incident angle and a first weight corresponding to each incident angle, wherein the first weight corresponding to each incident angle is inversely related to the absolute value of the incident angle.
The inventor finds that in engineering practice, when the phase difference is calculated based on the measured receiving phase, and the incident angle theta is calculated, the calculated incident angle has the problems of large error and low accuracy, so that the conventional ultra-wideband, Bluetooth or other radio frequency devices have the problem of low direction-finding accuracy when direction-finding is carried out.
In step S102, referring to fig. 2, assuming that the value of the incident angle is negative when the target is on the right side of the perpendicular line of the two antenna units in fig. 2 and the value of the incident angle is positive when the target is on the left side of the perpendicular line, the method is based on
Figure BDA0001879616150000071
where α 1 and α 2 are the receiving phases of the first antenna element 1011 and the second antenna element 1012 for receiving the signal transmitted by the target, d is the distance between the two antenna elements, C is the speed of light, ω is the center frequency of the signal transmitted by the target, and π is the circumference ratio, and when (α 1- α 2) in the above formula is expressed as phase difference y, there is a difference
Figure BDA0001879616150000072
When d and co are not changed, the process,
Figure BDA0001879616150000073
is constant, the differentiation is carried out, then
Figure BDA0001879616150000074
Then
Figure BDA0001879616150000075
Therefore, when θ is 0 °, the error of the determined incident angle θ caused by the error of the measured phase difference y is the smallest, and when θ is 90 °, the error of the determined incident angle θ caused by the error of the measured phase difference y is the largest. Therefore, the first weight of each incident angle is determined according to the absolute value of each incident angle, the absolute value is large, the value of the first weight is low, the absolute value is small, and the value of the first weight is high, wherein the first weight value can be zero at the lowest, namely the data of the incident angle is directly rejected.
For example, when the absolute value of θ is in the [0 °, 30 ° ] interval, the first weight of the incident angle (or the phase difference characterizing the incident angle) is 1; when the absolute value of θ lies in the interval (30 °, 90 °), the first weight of the incident angle (or the phase difference characterizing the incident angle) is zero.
For another example, when the absolute value of θ is in the interval [0 °, 30 ° ], the first weight of the incident angle (or the phase difference representing the incident angle) is 1; the first weight of the angle of incidence (or the phase difference characterizing the angle of incidence) is 0.5 when the absolute value of theta lies in the (30 deg., 45 deg.) interval, and the first weight of the angle of incidence (or the phase difference characterizing the angle of incidence) is zero when the absolute value of theta lies in the (45 deg., 90 deg.) interval.
In this way, when the direction of the target is determined according to a plurality of incidence angles of the signal transmitted by the target relative to the antenna array, the incidence angle with large error is removed or the weight is reduced, the weight of the incidence angle with small error is increased, the intersection part of the incidence angle with high weight is more reliable to determine the direction of the target, the direction finding precision can be effectively improved, and the determined direction of the target is more accurate.
Optionally, the first weight corresponding to the incident angle is negatively correlated with the absolute value of the incident angle, and specifically includes: the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle historical moment; and/or the first weight corresponding to the incident angle is inversely related to the absolute value of the current moment of the incident angle.
The first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle historical time, namely, the current value of the incident angle is calculated according to the historical data of the incident angle. For example, IN one direction finding of the target, if there are 4 antenna units IN the antenna array, the antenna array may generate 6 incident angles (IN 1, IN2, and IN3.. IN6, respectively), and the target sequentially transmits 10 signals to the antenna array within 1 second IN this direction finding, so that the incident angle IN1 has 10 absolute values (V1, V2, and V3... V10, respectively), and when the 10 th signal transmitted by the target is received, the first weight corresponding to the absolute value V10 of the incident angle IN1 at the current time may be determined according to an average value of V1 and V2.. V9 of the incident angle IN1 at the historical time, and similarly, the first weights corresponding to the values of IN2 and IN3.. IN6 at the current time are determined respectively. For another example, the first weight for V2 may be determined from the value V1 of the angle of incidence IN1, the first weight for V3 may be determined from the value of V2, and so on.
The first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle at the current moment. For example, the first weight corresponding to the absolute value V10 of the incident angle IN1 at the current time is inversely related to the absolute value V10 of IN1 at the current time, i.e., the first weight corresponding to V10 is determined according to the obtained V10 at the current time.
The first weight corresponding to the incident angle is inversely related to the absolute value of the historical moment of the incident angle and the first weight corresponding to the incident angle is inversely related to the absolute value of the current moment of the incident angle; that is, the first weight corresponding to the incident angle is inversely related to the absolute values of the incident angle history time and the current time. For example, the first weight corresponding to V10 of the incident angle IN1 at the current time is determined according to the average value of V1, V2.. V9 of the incident angle IN1 at the historical time and V10 of the current time. For another example, the absolute value of the incident angle IN1 at the historical time IN one direction finding and the absolute value of the current time are kalman filtered, the first weight corresponding to the absolute value of the current time IN1 is determined, and the value of IN1 at the current time is corrected. For another example, the absolute value of the incident angle IN1 at the historical time and the absolute value of the current time IN the plurality of direction finding are kalman filtered, the first weight corresponding to the absolute value of the current time IN1 is determined, and the value of IN1 at the current time is corrected. Similarly, a first weight corresponding to the value of IN2, IN3.. IN6 at the current time is determined.
Thus, IN these embodiments, the direction of the target at the current time is determined based on the determined first weight corresponding to the value of IN1, IN2, IN3.. IN6 at the current time.
When the moving speed of the target is far less than the propagation speed of the signal in the air (for example, the moving speed of the target is the moving speed of a person, and the ultra-wideband signal is close to the speed of light in the air), the direction finding precision of the target in the direction finding process can be improved by the scheme of determining the current direction of the target through the absolute value of the incident angle at the historical moment, and the direction finding precision can be further improved by the scheme of determining the current direction of the target through the absolute value of the incident angle at the historical moment and the current moment.
Optionally, the number of the antenna units in the antenna array is N, and the number of the incident angles is
Figure BDA0001879616150000091
Wherein N is a positive integer greater than or equal to 3. For example, the number of antenna elements in the antenna array is 6, and any two antenna elements are combined to generate a total of 15 incident angles when receiving a signal transmitted by a targetIn some embodiments, only 3 incident angles are determined and the direction of the target is determined, while in the present embodiment, all 15 incident angles are determined, and the direction of the target is determined according to the first weights corresponding to the 15 incident angles.
Optionally, before determining the direction of the target according to each of the incident angles and the first weight corresponding to each of the incident angles, the method further includes: determining a second weight corresponding to each incident angle, wherein when the distance between two antenna units with opposite incident angles belongs to a first distance interval, the second weight corresponding to the incident angle belongs to the first interval; the determining the direction of the target according to each of the incident angles and the first weight corresponding to each of the incident angles specifically includes determining the direction of the target according to each of the incident angles, the first weight corresponding to each of the incident angles, and the second weight corresponding to each of the incident angles.
Wherein the second weight corresponding to the incident angle is related to the spacing of the antenna elements relative to the incident angle. For example, referring to fig. 3, a distance between the first antenna element 1011 and the second antenna element 1012 opposite to the incident angle θ 1 is d1, a distance between the first antenna element 1011 and the third antenna element 1013 opposite to the incident angle θ 2 is d2, a second weight corresponding to the incident angle θ 1 is associated with the distance d1, and a second weight corresponding to the incident angle θ 2 is associated with the distance d 2.
Optionally, when the distance between the two antenna units with the opposite incident angles does not belong to a first distance interval, the second weight corresponding to the incident angle belongs to a second interval, and any value of the first interval is greater than all values of the second interval. For example, the distance d1 belongs to the first distance interval
Figure BDA0001879616150000101
The second weight corresponding to the incident angle theta 1 belongs to the first interval [0.8, 1%]The spacing d2 does not belong to the first spacing interval
Figure BDA0001879616150000102
The second weight corresponding to the incident angle theta 2 belongs to the second interval [0, 0.2%]. Where λ is the half wavelength of the communication.
Optionally, the first distance interval is 0.8 to 1 times of a half wavelength of communication, that is, the interval
Figure BDA0001879616150000103
Since the phase is reversed to generate an error and require a larger amount of calculation to process the error when the distance between the antenna elements is too large (for example, more than 1 half wavelength) when the direction of the target is measured according to the phase difference method, it is difficult to determine the incident angle when the distance between the antenna elements is too small and the phase difference of the received target signal is large.
For example, the value of the first weight corresponding to the incident angle θ 1 is K11, the value of the corresponding second weight is K12, the value of the first weight corresponding to the incident angle θ 2 is K21, and the value of the corresponding second weight is K22, and the following processes are respectively performed: the final weight value corresponding to θ 1 is K11 × K12, and the final weight value corresponding to θ 2 is K21 × K22. For example, when there are k incident angles, the final weight values of the k incident angles are calculated based on the first weight and the second weight corresponding to each incident angle, respectively, and the direction of the target is determined based on the final weight values of the k incident angles.
In this way, the direction of the target is determined based on the incident angles, the first weights corresponding to the incident angles, and the second weights corresponding to the incident angles, and the direction finding accuracy when the direction of the target is found is further improved.
Optionally, determining the second weight corresponding to the incident angle may be before determining the first weight corresponding to the incident angle, or may be after determining the second weight corresponding to the incident angle. Specifically, determining the second weight corresponding to the incident angle may include determining the second weight before determining the plurality of incident angles of the target transmitted signal relative to the antenna array in step S101, or determining the second weight after determining the plurality of incident angles of the target transmitted signal relative to the antenna array in step S101, before determining the first weight corresponding to the incident angle.
For example, referring to fig. 4, in one embodiment, the direction finding method includes:
s401, determining a second weight corresponding to the incident angle; the incidence angle is an included angle of a signal sent by a target relative to a perpendicular line of a connecting line of two antenna units in the antenna array; when the distance between the two antenna units with the opposite incident angles belongs to a first distance interval, a second weight corresponding to the incident angle belongs to the first interval;
in step S401, the second weight corresponding to the incident angle is determined according to the distance, which may be before the target sends the signal to the antenna array or after the target sends the signal. For example, before a target sends a signal, second weights of incidence angles relative to two antenna units in the antenna array are determined according to the distance between the two antenna units, and the determined second weights are predicted to be locally stored in a direction-finding device or on a direction-finding resolving server. Wherein the value of the second weight may take zero at a minimum.
S402, determining a plurality of incidence angles of the signal transmitted by the target relative to an antenna array;
in step S402, the target transmits a signal to an antenna array in the direction-finding device, and after the antenna array receives the signal transmitted by the target, the direction-finding device (or the direction-finding calculation server) determines values of a plurality of incident angles when receiving the signal, or determines a plurality of phase differences or a plurality of phase values for representing the plurality of incident angles.
And S403, determining the direction of the target according to each incident angle, a first weight corresponding to each incident angle and a second weight corresponding to each incident angle, wherein the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle.
In step S403, for example, the value of the first weight corresponding to the incident angle θ 1 is K11, the value of the corresponding second weight is K12, the value of the first weight corresponding to the incident angle θ 2 is K21, the value of the corresponding second weight is K22.. the value of the first weight corresponding to the incident angle θ m is Km1, the value of the corresponding second weight is Km2, and the final weight values are determined to be: k11 × K12, K21 × K22.. Km1 × Km2, thereby determining the direction of the target. Wherein the value of the first weight may take zero at a minimum.
For related implementation in this embodiment, reference may be made to the description of the foregoing embodiment, which is not described herein again.
Optionally, the first weight corresponding to the incident angle is negatively correlated with the absolute value of the incident angle, and specifically includes: when the absolute value of the incidence angle does not belong to a first angle interval, the first weight corresponding to the incidence angle is zero; when the distance between the two antenna units with the opposite incident angles does not belong to the first distance interval, the second weight corresponding to the incident angle belongs to the second interval, which specifically includes: when the distance between the two antenna units with the opposite incident angles does not belong to a first distance interval, the second weight corresponding to the incident angles is zero; the determining the direction of the target according to each of the incident angles, the first weight corresponding to each of the incident angles, and the second weight corresponding to each of the incident angles specifically includes: screening out a credible incident angle of which the first weight corresponding to the incident angle or the second weight corresponding to the incident angle is not zero from all the incident angles; and performing Kalman filtering processing on each credible incidence angle to determine the direction of the target.
For example, when the absolute value of an incident angle belongs to the [0 °, 60 ° ] interval, the first weight corresponding to the incident angle (or the phase difference characterizing the incident angle) is 1; when the absolute value of the incident angle belongs to the (60 °, 90 ° ] interval, the first weight value of the incident angle (or the phase difference characterizing the incident angle) is zero.
For example, when the distance between two antenna elements with opposite incident angles belongs to the first distance interval
Figure BDA0001879616150000121
When the second weight is 1, the second weight corresponding to the incident angle is 1; when the distance does not belong to the first distance interval
Figure BDA0001879616150000122
The second weight corresponding to the incident angle is zero, where λ is a half communication wavelength.
For example, IN one embodiment, the antenna array receives signals to generate 6 incident angles (IN 1, IN2, and IN3.. IN6), determines whether the first weight and the second weight corresponding to the incident angles IN1 and IN2.. IN6 are zero values, determines that only the first weight corresponding to the incident angle IN3 is zero, discards the incident angle IN3, and selects and retains the other five incident angles IN1, IN2, IN4, IN5, and IN6 as reliable incident angles, and performs kalman processing to determine the direction of the target.
Thus, the direction-finding precision is further improved while the smoothness of Kalman filtering is improved.
Optionally, performing kalman filtering processing on each trusted incident angle to determine the direction of the target specifically includes:
the trusted angle of incidence comprises: θ 1, θ 2, θ 3.. θ m; wherein at time k, the trusted angle of incidence comprises: theta 1k、θ2k、θ3k...θmk；
Performing extended Kalman filtering processing on each credible incidence angle; wherein the state transition equation in the extended Kalman filtering process is
Figure BDA0001879616150000131
Wherein,
Figure BDA0001879616150000132
a state predictor for a unit vector pointing in the direction of the target at time k,
Figure BDA0001879616150000133
the state optimal estimation value of the unit vector pointing to the direction of the target at the moment k-1; wherein the measurement equation in the extended Kalman filtering process is zk＝h(xk)+vk，
Wherein
Figure BDA0001879616150000134
vkTo measure noise, rkIs a unit vector pointing in the direction of the target at the time k, the
Figure BDA0001879616150000135
Wherein, the1、l2、l3...lmAnd the unit vectors are respectively unit vectors of the connecting line directions of the two antenna units with the corresponding credible incidence angles.
Specifically, the equations and calculation process in the extended kalman filter processing are as follows:
xk＝f(xk-1,uk)+wk...(1)；
zk＝h(xk)+vk...(2)；
Figure BDA0001879616150000136
Figure BDA0001879616150000137
Figure BDA0001879616150000141
Figure BDA0001879616150000142
Pk′←(I-GkHk)Pk...(7)；
the above formula (1) is an equation of state, xkIs the state value at time k, ukIs the value of the control quantity at time k, wkProcess noise at time k; formula (2) is the measurement equation, zkMeasured at time k, vkThe measurement noise at time k; equation (3) is a state transition equation, and the optimal estimated value of the state at the time k-1 is obtained
Figure BDA0001879616150000143
Calculating a state prediction value at time k
Figure BDA0001879616150000144
In the formula (4), P is covariance and represents the correlation of each state quantity in the state equation, and the optimal estimated value P of the covariance P at the moment of k-1 is usedk-1' calculating the predicted value P of the covariance P at time kkQ is the process noise covariance, Q and wkIn relation, F is the Jacobian matrix of F (x, u); in formula (5), G is Kalman gain, R is measurement noise covariance, and R and vkRelated to, HkKalman gain G at time k, Jacobian matrix of h (x)kAccording to P of k timekDetermining a predicted value P of the covariance P at time kkDetermined according to equation (4); expressions (6) and (7) are predicted values P of the covariance P at the time k is determined from expressions (1) to (5)kAnd Kalman gain GkThen, the state prediction value at the time k is calculated
Figure BDA0001879616150000145
Predicted value P of covariance P at time kkCorrecting to obtain the optimal state estimation value at the k moment
Figure BDA0001879616150000146
Covariance Poptimum estimate P at sum time kkOptimal estimation value of 'k' time
Figure BDA0001879616150000147
State prediction value for time k +1
Figure BDA0001879616150000148
Predicted value P of sum covariance Pk+1Calculating (1); wherein Z in the formula (6)kThe measured value measured from the measuring device at time k.
For example, in one embodiment, taking the example of a measurement device including three antenna elements, assume that no control quantity is input at the target and the direction of the target between time k-1 and time k remains unchanged, i.e., ukThe predicted value of the state at the current time (i.e. time k) of the target is equal to the optimal estimated value of the state at the previous time (i.e. time k-1), and according to the above equations (1) and (3), there are: x is the number ofk＝xk-1+wk(8)，
Figure BDA0001879616150000149
In the formula (8), xkIs the unit vector pointing in the target direction at time k. The Jacobian matrix F of F (x, u) in the equation of state is I, i.e. F in equation (4) abovek＝Fk-1I, P at the previous moment can be passedk-1' determination of P at the present timek. Referring to fig. 5, the antenna array includes a first antenna unit 1011 (number 1011), a second antenna unit 1012 (number 1012) and a third antenna 1013 (number 1013), where h (x) in the above formula (2) is definedk) The following were used:
Figure BDA0001879616150000151
in the formula (10), r iskA unit vector pointing in the target direction at time k, rk＝[ak,bk,ck]，ak 2+bk 2+ck 2＝1，rkIn contrast to the incident direction of the signal transmitted by the target in fig. 5 (i.e., P1, P2, and P3 which are parallel to each other in fig. 5), the incident angles of the signal in fig. 5 are θ 1, θ 2, and θ 3, and θ 1 is at the time kk、θ2kAnd theta 3k。l1、l2、l3Unit vectors l pointing to the direction of the antenna unit with a larger number in the direction of the connection line of the two antenna units with opposite incidence angles1＝[l11,l12,l13]，l2＝[l21,l22,l23]，l3＝[l31,l32,l33](ii) a Calculating h (x)k) Jacobian matrix HkAnd then:
Figure BDA0001879616150000152
r in formula (11)kEqual to the predicted value of the state of the target direction at the current time (i.e. time k)
Figure BDA0001879616150000153
According to formula (9) having
Figure BDA0001879616150000154
H for the current time may be determinedkTo determine G at the current timek(ii) a At this time, P is determinedkAnd GkThen, the measuring device (i.e., direction-finding device) measures θ 1 at the current time (k time)k、θ2kAnd theta 3kThus having
Figure BDA0001879616150000155
Will be calculated
Figure BDA0001879616150000156
And GkAnd Z in the formula (12)kCan be substituted by formula (6)
Figure BDA0001879616150000157
Will have calculated Pk、HkAnd GkSubstitution of formula (7) to obtain Pk'. Wherein theta 1k、θ2kAnd theta 3kMay be the trusted angle of incidence screened by the first weight and the second weight.
Thus, according to the above equation (1) (2. (12), the optimal estimation value of the target direction at the current time is determined from the optimal estimation value of the state at the current time and the plurality of incident angles measured at the current time in the target direction. In particular, wkAnd vkCan be empirically preset to a non-zero value to yield Qk-1And R, for simple calculation, the target initial direction x can be presetInitialIs a zero vector.
In some other embodiments, the trusted angles of incidence are m, and at time k, the trusted angles of incidence include: theta 1k、θ2k、θ3k...θmk；
Figure BDA0001879616150000161
In the kalman filter processing or the extended kalman filter processing, the greater the number of the credible incident angles, the more the optimal estimated value is obtained
Figure BDA0001879616150000162
The closer to the true value, the higher the direction finding accuracy.
In particular, in some embodiments, the antenna array in the direction-finding device is fixed, said/1、l2、l3...lmThe direction of the vector is known and remains unchanged. In other embodiments, the direction-finding device itself moves, and the antenna array also moves, and at this time, the attitude angle of the antenna array can be obtained according to the attitude sensor in the direction-finding device, so as to determine the l1、l2、l3...lmAnd vector and provide to the Kalman filter.
The direction finding method provided by the embodiment improves the continuity of target direction data through extended Kalman filtering processing, and further improves the direction finding precision. The calculation processing is carried out in a vector and matrix mode, the calculation amount is smaller and the processing speed is higher relative to the calculation of the angle value, so that signals with higher frequency can be received and processed in one direction finding process, and the direction finding precision is further improved. The more the number of the credible incidence angles is, the better the effect of improving the direction-finding precision is.
Optionally, the number of the antenna units in the antenna array is specifically 2n, and the number of the incident angles is two, where n is a positive integer greater than or equal to 2; and (2n-1) antenna units form a polygonal array, and one antenna unit is arranged at the center of the polygonal array, so that connecting lines of any two adjacent antenna units are not parallel.
For example, taking n as 3 as an example, referring to fig. 6, the antenna array includes six antenna elements, a first antenna element 601, a second antenna element 602, a third antenna element 603, a fourth antenna element 604, and a fifth antenna element 605 form a pentagonal array, and a sixth antenna element 606 is disposed in the center of the pentagonal array. The first antenna unit 601 is respectively adjacent to the second antenna unit 602, the fifth antenna unit 605 and the sixth antenna unit 606, and the first antenna unit 601 is not adjacent to the third antenna unit 603 or the fourth antenna unit 604; the sixth antenna unit 606 is adjacent to the other five antenna units; the adjacent relationship of the remaining antenna units is the same, and the connecting lines of any two adjacent antenna units in the antenna array are not parallel. For example, although the connection line of the first antenna element 601 and the third antenna element 603 is parallel to the connection line of the fourth antenna element 604 and the fifth antenna element 605, the first antenna element 601 and the third antenna element 603 are not adjacent.
Referring to fig. 5, when the connecting lines of the two antenna elements are not parallel, values of a plurality of incident angles of a signal transmitted by a target with respect to the antenna array are different, and first weights corresponding to the plurality of incident angles are also different, and when the direction of the target is determined according to each of the incident angles and the first weight corresponding to each of the incident angles, it does not happen that the first weight of one incident angle is zero, and the first weights of other incident angles which are the same as the value of the incident angle are also zero, thereby causing a decrease in direction-finding accuracy.
Referring to fig. 7, when it is determined that an included angle of a signal transmitted by a target with respect to a perpendicular line connecting the first antenna unit 701 and the second antenna unit 702 is 80 ° by the measured phase difference, the first weight value is zero; the incident angle of the signal with respect to the third antenna element 703 and the fourth antenna element 704 is also 80 °, and the first weight value thereof is zero, and the incident angle of the signal with respect to the fifth antenna element 705 and the sixth antenna element 706 is also 80 °, and the first weight value thereof is also zero; the accuracy is reduced when the target direction is determined according to the values of the plurality of incident angles, and further, the effect of improving the direction-finding accuracy based on the kalman filtering process is poor due to the small number of the credible incident angles.
Therefore, when the number of the antenna units in the antenna array is the same and the connecting lines of any two adjacent antenna units are not parallel, the direction finding precision is higher. Therefore, the scheme provided by the embodiment of the invention effectively utilizes each antenna unit in the antenna array, and the direction finding precision is higher.
Considering and determining a second weight corresponding to each incident angle, wherein when the distance between two antenna units with opposite incident angles belongs to a first distance interval, the second weight corresponding to the incident angle belongs to the first interval; then, one antenna unit is arranged at the center of the polygonal array, so that the distance between the antenna unit arranged at the center and other antenna units is equal, and thus more antenna units with the distance belonging to the first distance interval are provided, and each antenna unit in the antenna array is further effectively utilized, thereby improving the direction finding precision. Optionally, the first distance interval is 0.8 to 1 times of a half communication wavelength.
Optionally, the polygon array is specifically a regular polygon array. For example, referring to fig. 6, a first antenna element 601, a second antenna element 602, a third antenna element 603, a fourth antenna element 604, and a fifth antenna element 605 form a regular pentagonal array, and a unit vector l pointing to a direction of a connection line of two antenna elements with opposite incident angles and pointing to a direction of a numbered antenna element is larger1、l2、l3...l6The angle between the plurality of incident angles is determined to be uniform no matter what direction the target is located in the space, so that the direction finding precision is higher when the direction of the target in the range of 360 degrees is found.
Optionally, the polygonal array is specifically a regular trilateral array, a regular pentagonal array, a regular heptagonal array, or a regular nonagonal array.
Optionally, referring to fig. 6, the number of the antenna units in the antenna array is specifically six, and the polygonal array is specifically a regular pentagonal array. Thus, when the requirement that the connecting lines of any two adjacent antenna units are not parallel is met, the first distance interval (0.8 to 1 time of the half-wavelength of communication) can be met by the distance between two antenna units (for example, the distance between the first antenna unit 601 and the second antenna unit 602) on the side of the regular pentagon and the distance between the sixth antenna unit 606 and the other antenna units (for example, the distance between the sixth antenna unit 606 and the first antenna unit 601) at the center, so that on the premise that the number of the antenna units is not increased, each antenna unit is effectively utilized, the number of the credible incident angles is ensured to be the maximum, and the direction-finding accuracy is further improved.
Optionally, a value range of the first weight includes zero, and/or a value of the second interval includes zero. And when the first weight value or the second weight value corresponding to the incident angle is zero, abandoning the incident angle, and not performing Kalman filtering processing so as to improve the stability of Kalman filtering.
According to the direction finding method provided by the embodiment of the disclosure, high-precision direction finding of a plurality of targets in different directions can be realized simultaneously only by one direction finding device. Specifically, the signal sent by the target carries an identifier of the target, and the identifiers of different targets are different.
For related implementation in the embodiments of the present disclosure, reference may be made to the description of the foregoing embodiments, which are not described herein again.
Based on the same inventive concept, as shown in fig. 8, the disclosed embodiment further provides a direction-finding device 80, including: a processing module 801 configured to determine a plurality of incident angles of a signal transmitted by a target with respect to an antenna array, where the incident angles are included angles of the signal with respect to a perpendicular line connecting two antenna units in the antenna array; and determining the direction of the target according to each incident angle and a first weight corresponding to each incident angle, wherein the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle. For example, the processing module 801 may specifically include a CPU (central processing unit), an MCU (micro control unit), an ARM (embedded processor), and the like.
Optionally, referring to fig. 8, the direction-finding device 80 further includes:
an antenna arrangement 802 comprising the antenna array 8021; the number of the antenna units in the antenna array is N, the number of the incident angles is N, and N is a positive integer greater than or equal to 3.
The antenna device 802 and the processing module 801 may be integrated in one hardware device (for example, integrated in one direction-finding base station), or may be separately disposed in two separate hardware devices and communicatively connected, for example, the antenna device 802 is independently a hardware device disposed in a measurement area, the processing module 801 is specifically a server disposed in a non-measurement area, and the antenna device 802 and the processing module 801 are communicatively connected through WIFI, bluetooth, 4G or 5G to transmit data and instructions.
Optionally, the direction-finding device 80, wherein: the processing module 801 is further configured to determine a second weight corresponding to each of the incident angles before determining the direction of the target according to each of the incident angles and a first weight corresponding to each of the incident angles, where the second weight corresponding to each of the incident angles belongs to a first interval when the distance between two antenna units with the opposite incident angles belongs to the first interval; and the processing module 801 is specifically configured to determine the direction of the target according to each of the incident angles, a first weight corresponding to each of the incident angles, and a second weight corresponding to each of the incident angles.
Alternatively, referring to fig. 9, the direction-finding device 80, wherein:
the antenna apparatus 802 further includes a preprocessing module 8022 connected to each of the antenna elements in the antenna array 8021; the preprocessing module 8022 is configured to determine the phase of the signal received by each antenna element and provide the phase to the processing module, so that the processing module 801 determines each incident angle. The preprocessing module 8022 capable of determining the phase of the received signal may be a radio frequency processing module, which generally includes a phase-locked loop, a mixer, a digital-to-analog conversion circuit, and other electronic devices; the processing module 801 may determine the angle of incidence by calculating a phase difference based on the plurality of phases determined by the preprocessing module 8022.
Optionally, the direction-finding device 80, wherein: the antenna units in the antenna array 8021 are specifically cross-shaped omnidirectional antennas. Taking six antenna elements as an example, referring to fig. 10, an antenna array 8021 includes six cross-shaped omnidirectional antennas disposed on a substrate. With further reference to fig. 11, the distance (H in fig. 11) from the substrate to the center of the pattern (at the circle in fig. 11) of the antenna element transmitting and receiving the electromagnetic wave accounts for the height (H in fig. 11) of the antenna element
Figure BDA0001879616150000201
The larger the antenna array of antenna elements is, the more the signals of the antenna elements located at the center of the polygon (e.g., the sixth antenna element 606 in fig. 6) are located when receiving and transmitting electromagnetic wavesthe less the antenna elements (e.g., first, second, third, fourth, and fifth antenna elements in fig. 6) at the vertices of the polygon are obscured, i.e., the greater the angle α in fig. 11
Figure BDA0001879616150000202
The value is large, so that in the polygonal antenna array, the cross-shaped omnidirectional antenna positioned at the center is slightly influenced by shielding, and the direction-finding precision is further improved.
Optionally, the direction-finding device 80, wherein: the antenna units in the antenna array 8021 are specifically horn-type omnidirectional antennas. Taking six antenna elements as an example, referring to fig. 12, an antenna array 8021 includes six butterfly omnidirectional antennas disposed on a substrate. The butterfly antenna is narrow, so that in the polygonal antenna array, the cross butterfly antenna at the center is slightly influenced by the shielding of the butterfly antenna at the vertex of the polygon, and the direction-finding precision is further improved.
Optionally, the direction-finding device, wherein: the number of the antenna units in the antenna array is specifically 2n, the number of the incident angles is one, and n is a positive integer greater than or equal to 2; and (2n-1) antenna units form a polygonal array, and one antenna unit is arranged at the center of the polygonal array, so that connecting lines of any two antenna units are not parallel.
Optionally, the direction-finding device, wherein: the antenna array comprises six antenna units, and the polygonal array is a regular pentagonal array. Referring to fig. 6, 10 and 12, the polygonal array is embodied as a regular pentagonal array.
Optionally, the first distance interval is 0.8 times to 1 time of a half wavelength of communication. For example, when the signal received and transmitted by the antenna unit is an ultra-wideband signal with a center frequency of 4Ghz, the half wavelength of the communication is about 3.75 cm.
According to the direction-finding device provided by the embodiment of the disclosure, only one direction-finding device can achieve high-precision direction finding of multiple targets at the same time.
For the implementation of the embodiment of the direction finding device, reference may be made to the description of the embodiment of the direction finding method, and details are not described here.
Based on the same inventive concept, the embodiment of the present disclosure further provides an ultra-wideband direction finding system, including: including label 1301, base station 1302 and server 1303, wherein: the tag 1301 is configured to transmit an ultra wideband signal to the base station; the base station 1302 includes an antenna device and a preprocessing module; the antenna device comprises an antenna array; the antenna array comprises six antenna units, five antenna units form a regular pentagonal array, and one antenna unit is arranged at the center of the regular pentagonal array; the antenna device is configured to receive the ultra-wideband signal; the preprocessing module is configured to determine phases of the ultra-wideband signals received by the antenna units and provide the phases to the server; the server 1303 is configured to determine a direction of an object according to each phase difference, a first weight corresponding to each phase difference, and a second weight corresponding to each phase difference; wherein the phase difference is a difference between the two phases; a first weight corresponding to the phase difference is inversely related to an absolute value of the phase difference; and when the distance between the two antenna units belongs to a first distance interval, the second weight corresponding to the phase difference of the ultra-wideband signals received by the two antenna units belongs to the first interval.
Optionally, the server 1303 is further configured to determine the distance of the target with respect to the base station 1302 through TOF (time of flight) or TDOA (time difference of arrival), so that high-precision position information of the target can be determined according to the high-precision direction and distance.
The ultra-wideband direction-finding system provided by the embodiment of the disclosure can realize high-precision direction finding and positioning of a plurality of targets (namely a plurality of labels) at the same time. The labels of different labels are different, and the signal sent by the label carries the label corresponding to the label.
For the related implementation in the embodiment of the ultra-wideband direction finding system, reference may be made to the descriptions of the embodiments of the identity determination method and the identity determination device, which are not described herein again.
In the various embodiments provided in the present disclosure, it should be understood that the disclosed related devices, modules and methods may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, each functional module or functional unit in each embodiment of the present invention may be integrated into one processing module or processing unit, or each module or each unit may exist alone physically, or two or more modules or units are integrated into one module or unit. The integrated module or unit may be implemented in the form of hardware, or may be implemented in the form of a software functional unit.
The integrated module or unit may be stored in a computer-readable storage medium if it is implemented in the form of a software functional module or software functional unit and sold or used as a separate product. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer processor to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

Claims (19)

1. A method of direction finding comprising:
determining a plurality of incidence angles of a signal sent by a target relative to an antenna array, wherein the incidence angles are included angles of the signal relative to a perpendicular line of a connecting line of two antenna units in the antenna array;
and determining the direction of the target according to each incident angle and the first weight corresponding to each incident angle, wherein the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle.
2. The direction-finding method of claim 1, wherein the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle, specifically comprising:
the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle historical moment; and/or the presence of a gas in the gas,
the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle at the current moment.
3. A method of direction finding as claimed in claim 2, wherein:
the number of the antenna units in the antenna array is N, and the number of the incidence angles is C2NWherein N is a positive integer greater than or equal to 3.
4. The direction finding method of claim 3, before determining the direction of the target according to each of the incident angles and the first weight corresponding to each of the incident angles, further comprising:
determining a second weight corresponding to each incident angle, wherein when the distance between two antenna units with opposite incident angles belongs to a first distance interval, the second weight corresponding to the incident angle belongs to the first interval;
the determining the direction of the target according to each of the incident angles and the first weight corresponding to each of the incident angles specifically includes determining the direction of the target according to each of the incident angles, the first weight corresponding to each of the incident angles, and the second weight corresponding to each of the incident angles.
5. The direction-finding method according to claim 4, wherein when the distance between the two antenna elements with the opposite incident angles does not belong to a first distance interval, the second weight corresponding to the incident angle belongs to a second interval, and any value of the first interval is greater than all values of the second interval, wherein:
the first interval is 0.8 to 1 times of the half wavelength of communication.
6. The direction-finding method of claim 4, wherein:
the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle, and specifically includes: when the absolute value of the incidence angle does not belong to a first angle interval, the first weight corresponding to the incidence angle is zero;
when the distance between the two antenna units with the opposite incident angles does not belong to the first distance interval, the second weight corresponding to the incident angle belongs to the second interval, which specifically includes: when the distance between the two antenna units with the opposite incident angles does not belong to a first distance interval, the second weight corresponding to the incident angles is zero;
the determining the direction of the target according to each of the incident angles, the first weight corresponding to each of the incident angles, and the second weight corresponding to each of the incident angles specifically includes: screening out a credible incident angle of which the first weight corresponding to the incident angle or the second weight corresponding to the incident angle is not zero from all the incident angles; and performing Kalman filtering processing on each credible incidence angle to determine the direction of the target.
7. The direction-finding method of claim 6, wherein:
the trusted angle of incidence comprises: θ 1, θ 2, θ 3.. θ m; wherein, at time k, the signal incidence angle comprises: theta 1k、θ2k、θ3k...θmk；
The kalman filtering process performed on each of the trusted incident angles specifically includes: performing extended Kalman filtering processing on each credible incidence angle; wherein the state transition equation in the extended Kalman filtering process is
Figure FDA0001879616140000021
Wherein,
Figure FDA0001879616140000022
a state predictor for a unit vector pointing in the direction of the target at time k,
Figure FDA0001879616140000023
the state optimal estimation value of the unit vector pointing to the direction of the target at the moment k-1; wherein the measurement equation in the extended Kalman filtering process is zk＝h(xk)+vkWherein
Figure FDA0001879616140000024
vkTo measure noise, rkIs a unit vector pointing in the direction of the target at the time k, the
Figure FDA0001879616140000025
Wherein, the1、l2、l3...lmAnd the unit vectors are respectively unit vectors of the connecting line directions of the two antenna units with the corresponding credible incidence angles.
8. A method of direction finding as claimed in any one of claims 2 to 7 wherein:
the number of the antenna units in the antenna array is specifically 2n, and the number of the incidence angles is
Figure FDA0001879616140000031
Wherein n is a positive integer greater than or equal to 2; and (2n-1) antenna units form a polygonal array, and one antenna unit is arranged at the center of the polygonal array, so that connecting lines of any two adjacent antenna units are not parallel.
9. The direction-finding method of claim 8, wherein:
the polygon array is specifically a regular polygon array.
10. A method of direction finding as claimed in any one of claims 1 to 7 wherein:
the value range of the first weight includes zero, and/or the value of the second interval includes zero.
11. A direction-finding device comprising:
the antenna array comprises a processing module, a receiving module and a processing module, wherein the processing module is configured to determine a plurality of incidence angles of a signal sent by a target relative to the antenna array, and the incidence angles are included angles of the signal relative to a perpendicular line of a connecting line of two antenna units in the antenna array; and determining the direction of the target according to each incident angle and a first weight corresponding to each incident angle, wherein the first weight corresponding to the incident angle is inversely related to the absolute value of the incident angle.
12. The direction-finding device of claim 11, further comprising:
an antenna arrangement comprising the antenna array; wherein the number of the antenna units in the antenna array is N, and the number of the incident angles is N
Figure FDA0001879616140000032
Wherein N is a positive integer greater than or equal to 3.
13. The direction-finding device of claim 12, wherein:
the processing module is further configured to determine a second weight corresponding to each incident angle before determining the direction of the target according to each incident angle and a first weight corresponding to each incident angle, wherein the second weight corresponding to each incident angle belongs to a first interval when the distance between two antenna units with opposite incident angles belongs to the first interval; and the number of the first and second groups,
the processing module is specifically configured to determine the direction of the target according to each of the incident angles, a first weight corresponding to each of the incident angles, and a second weight corresponding to each of the incident angles.
14. The direction-finding device of claim 12, wherein:
the antenna device also comprises a preprocessing module which is respectively connected with each antenna unit; wherein the pre-processing module is configured to determine a phase at which each of the antenna elements receives the signal and provide the phase to the processing module such that the processing module determines each of the angles of incidence.
15. The direction-finding device of claim 12, wherein:
the antenna units in the antenna array are specifically cross omnidirectional antennas.
16. The direction-finding device of any one of claims 12-15, wherein:
the number of the antenna units in the antenna array is specifically 2n, and the number of the incidence angles is
Figure FDA0001879616140000041
Wherein n is a positive integer greater than or equal to 2; and (2n-1) antenna units form a polygonal array, and one antenna unit is arranged at the center of the polygonal array, so that connecting lines of any two adjacent antenna units are not parallel.
17. The direction-finding device of claim 16, wherein:
the antenna array comprises six antenna units, and the polygonal array is a regular pentagonal array.
18. The direction-finding device of claim 17, wherein:
the first interval is 0.8 to 1 times of the half wavelength of communication.
19. An ultra-wideband direction finding system comprising a tag, a base station and a server, wherein:
the tag is configured to transmit an ultra wideband signal to the base station;
the base station comprises an antenna device and a preprocessing module; the antenna device comprises an antenna array; the antenna array comprises six antenna units, five antenna units form a regular pentagonal array, and one antenna unit is arranged at the center of the regular pentagonal array; the antenna device is configured to receive the ultra-wideband signal; the preprocessing module is configured to determine phases of the ultra-wideband signals received by the antenna units and provide the phases to the server;
the server is configured to determine the direction of the target according to each phase difference, a first weight corresponding to each phase difference and a second weight corresponding to each phase difference; wherein the phase difference is a difference between the two phases; a first weight corresponding to the phase difference is inversely related to an absolute value of the phase difference; and when the distance between the two antenna units belongs to a first distance interval, the second weight corresponding to the phase difference of the ultra-wideband signals received by the two antenna units belongs to the first interval.
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