CN113985345A - Ultra-wideband correction amplitude-phase fusion direction finding method and system - Google Patents

Ultra-wideband correction amplitude-phase fusion direction finding method and system Download PDF

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CN113985345A
CN113985345A CN202111172561.6A CN202111172561A CN113985345A CN 113985345 A CN113985345 A CN 113985345A CN 202111172561 A CN202111172561 A CN 202111172561A CN 113985345 A CN113985345 A CN 113985345A
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amplitude
phase
vector
finding
correction
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徐思远
李宏圆
李霄
姚群
马干军
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723 Research Institute of CSIC
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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
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14—Systems for determining direction or deviation from predetermined direction
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F16/00—Information retrieval; Database structures therefor; File system structures therefor
    • G06F16/20—Information retrieval; Database structures therefor; File system structures therefor of structured data, e.g. relational data
    • G06F16/22—Indexing; Data structures therefor; Storage structures
    • G06F16/2228—Indexing structures
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F16/00—Information retrieval; Database structures therefor; File system structures therefor
    • G06F16/20—Information retrieval; Database structures therefor; File system structures therefor of structured data, e.g. relational data
    • G06F16/25—Integrating or interfacing systems involving database management systems
    • G06F16/252—Integrating or interfacing systems involving database management systems between a Database Management System and a front-end application

Abstract

The invention discloses an ultra-wideband correction amplitude-phase fusion direction finding method and a system, wherein an FPGA (field programmable gate array) is used as a main control chip of the system and internally processes PDW (product data word) information, and the ultra-wideband correction amplitude-phase fusion direction finding method comprises the following specific steps: the method comprises the steps of arranging a direction-finding antenna array on a rotary table, connecting a correction source with a transmitting antenna to serve as a radiation source, firstly carrying out multichannel amplitude correction to reduce inherent errors of channels, then utilizing the rotary table to rotate the direction-finding antenna to obtain the amplitude and phase difference of radiation source signals in different directions of 0-360 degrees, generating n-channel characteristic vectors, storing the characteristic vectors according to the rotating direction of the direction-finding antenna and the known frequency of the correction source, forming a database after processing, finally carrying out correlation calculation on data calculated in real time and the database during direction finding to obtain a direction angle, and outputting a processing result. The invention can effectively reduce the inherent error of the system channel and realize higher direction-finding precision with lower equipment quantity.

Description

Ultra-wideband correction amplitude-phase fusion direction finding method and system
Technical Field
The invention belongs to the technical field of electronic information direction finding, and particularly relates to an ultra-wideband correction amplitude-phase fusion direction finding method and system.
Background
In recent years, the rapid development of the fields of communication, radar and electronic countermeasure, new system radars are more and more applied, the electromagnetic environment is higher and higher in density and complex, and the development of a broadband digital receiver with ultra wide band, high sensitivity, large dynamic range and simultaneously arriving signal adaptability is not slow.
At present, the main methods for measuring the direction of an incoming wave include a amplitude comparison system, a time difference system, a spatial spectrum system, an interferometer system and the like. The amplitude comparison system is based on different measuring directions of the amplitude of the incoming wave receiving signals in different directions by utilizing the directional characteristics of the direction-finding antenna array during the traveling of the radio wave. The time difference system determines the arrival direction of the electric wave by measuring the time difference of the electric wave reaching each direction-finding antenna unit of the direction-finding antenna array during the traveling of the electric wave. The space spectrum system is still in a research and test stage, and the broadband direction-finding antenna, the antenna array elements and the multichannel receiver are required to have consistent electrical performance. The interferometer system determines the incoming wave direction according to different receiving phases and different phase differences of direction-finding antenna units when electric waves from different directions reach the direction-finding antenna array during the traveling of the electric waves, but when the antenna spacing is larger than 0.5 wavelength, phase ambiguity is caused, and a long and short baseline combination mode is often adopted, so that the system requirement is high.
Disclosure of Invention
The invention aims to provide an ultra-wideband correction amplitude-phase fusion direction finding method and system, which are based on an FPGA and solve the problems of low precision, complexity and high cost of the existing direction finding method.
The technical solution for realizing the purpose of the invention is as follows:
an ultra-wideband correction amplitude-phase fusion direction finding method comprises the following steps:
multichannel amplitude correction: correcting by using a fixed power point, obtaining n paths of received amplitude values under different powers after sweeping, fitting a curve, and taking the corresponding amplitude on the fitted curve as a calculation amplitude according to the signal power during direction finding to reduce the inherent amplitude error;
and (3) forming a breadth-phase fusion database: arranging a direction-finding antenna array on a rotary table, setting signal frequency, acquiring the amplitude and phase difference of radiation source signals with different directions of 0-360 degrees, calculating according to n channels to form characteristic vectors, storing the characteristic vectors according to the rotation direction and the signal frequency of the direction-finding antenna, processing by an interpolation value smoothing algorithm, and finally forming a correction table database;
database-based direction finding: when a certain direction is measured in real time, acquiring imaginary real parts and corrected amplitudes of n channels, calculating to obtain a front-end channel alignment amplitude-phase vector, indexing to a characteristic vector in a database according to frequency, calculating complex numbers and performing modulus on all angles, and searching for an azimuth corresponding to the maximum value, wherein the azimuth is a direction finding result.
An ultra-wideband correction amplitude-phase fusion direction-finding system comprises a correction source, an upper computer, an FPGA (field programmable gate array), a receiver and a rotary table;
the correction source is connected with a signal of an upper computer and is connected with a transmitting antenna as a radiation source;
the turntable is in signal connection with an upper computer, controls the orientation of the receiver and is used for acquiring the amplitude and phase difference of radiation source signals in different orientations of 0-360 degrees;
the FPGA is connected with an upper computer through a serial port and transmits a real-time processing result to the upper computer; the FPGA firstly corrects the multichannel amplitude, and the corresponding amplitude on the fitting curve is taken as the calculated amplitude according to the signal power during direction finding; then obtaining the amplitude and phase difference of the radiation source signals in different directions of 0-360 degrees, calculating according to n channels to form characteristic vectors, storing the characteristic vectors according to the rotating directions and signal frequencies of the direction-finding antenna, processing through an interpolation smoothing algorithm, and finally generating a correction table database; and during real-time direction finding, acquiring imaginary real parts and corrected amplitudes of the n channels, calculating to obtain an alignment amplitude-phase vector of a front-end channel, indexing to a characteristic vector in a database according to frequency, calculating complex numbers and performing modulus on all angles, and searching an azimuth corresponding to the maximum value as a direction finding result.
Compared with the prior art, the invention has the following remarkable advantages:
the invention reduces the inherent error of the channel by multi-channel amplitude correction, fuses the signal amplitude and the phase information, fully utilizes the signal information received by each antenna array, collects data at a fixed angle, calculates the related vector to carry out smoothing and interpolation processing, generates a database, and carries out related operation on the actually measured data and the database during direction finding to obtain the direction, thereby effectively reducing the inherent error of the system channel, having low cost and realizing higher direction finding precision with lower equipment quantity.
Drawings
FIG. 1 is a basic block diagram of the architecture.
Fig. 2 is a diagram of the direction-finding principle and the structure.
Fig. 3 is a schematic diagram of the multichannel amplitude correction principle.
Fig. 4 is a flow chart of the calibration direction finding work.
Detailed Description
The invention is further described with reference to the following figures and embodiments.
With reference to fig. 1, the ultra-wideband correction amplitude-phase fusion direction-finding system provided by the invention uses an FPGA as a main control chip of the system, internally processes PDW information, and performs data processing through a Microblaze soft core built in the FPGA. The ultra-wideband correction amplitude-phase fusion direction finding method specifically comprises the following steps: the method comprises the steps of arranging a direction-finding antenna array on a rotary table, connecting a correction source with a transmitting antenna to serve as a radiation source, firstly carrying out multichannel amplitude correction to reduce inherent errors of channels, then utilizing the rotary table to rotate the direction-finding antenna to obtain the amplitude and phase difference of radiation source signals in different directions of 0-360 degrees, generating n-channel characteristic vectors, storing the characteristic vectors according to the rotating direction of the direction-finding antenna and the known frequency of the correction source, forming a database after processing, finally carrying out correlation calculation on data calculated in real time and the database during direction finding to obtain a direction angle, receiving a display control command, and outputting a processing result.
Fig. 2 shows the direction-finding principle and structure. The direction-finding antenna array is composed of a plurality of directional antennas according to a circular array (the value of the embodiment is n), and the center pointing included angles of any two adjacent antenna beams are consistent. After Microblaze initializes modules such as a serial port, an FIFO (first in first out) and a register control module, data processing is carried out on the obtained PDW, and information such as frequency and amplitude is analyzed to carry out subsequent direction finding.
As shown in fig. 3, the multipaths are theoretically linear in the sensitivity range, but due to the inherent errors, the amplitudes need to be corrected. Different powers of a self-detection source are set, the n-path channel receives discrete amplitude values, corresponding curves are marked as y1, y2 and y3 … … yn, a least square method is used for fitting the discrete points to obtain a straight line which is marked as y', and the correction process is as follows when real-time direction finding work is carried out in the later stage: and reading the amplitudes of the n channels, and marking the amplitudes as p1, p2, p3, … … and pn on corresponding curves, wherein the straight line fitted by the n points intersects the fitted straight line y 'at p' as the amplitude ampm of the corrected n paths, wherein m is 1, 2 … … n, and n is the number of antenna array elements.
As shown in fig. 4, the direction finding workflow is corrected. The amplitude of the correction multichannel is fitted to form a curve y' which is used as a basis for subsequent amplitude correction, then the rotary table is rotated to different angles, the correction source is set to have different frequencies, n channels form an n-dimensional table, and a database is formed after smoothing and internal difference processing, wherein the calculation process is specifically described as follows:
arranging a direction-finding antenna array on a rotary table, connecting a correction source with a transmitting antenna as a radiation source, rotating the direction-finding antenna to an angle by using the rotary table, setting a signal frequency, and acquiring imaginary parts q of the PDW of n channelsmReal part imOriginal amplitude ori-ampmThe subscript m is 1, 2 … … n, n is the number of antenna elements, and the phase atan2 (q) is obtained according to the imaginary real partm，im) The original amplitude is corrected by the above correction method to obtain a corrected amplitude p' marked as ampmFrom this, the front-end magnitude-phase vector a is calculated:
front end amplitude phase vector A ═ a1 a2…am…an] (1)
Wherein the m-th path of IQ data am＝{am.i，am·q}，am.i＝ampm*cos(atan2(qm，im))，am·q＝ampm*sin(atan2(qm，im))。
Calculating a front-end one-channel alignment magnitude-phase vector B:
Figure BDA0003293863810000031
wherein the content of the first and second substances,
Figure BDA0003293863810000041
and (3) for IQ data conjugation of the channel 1, carrying out multiple calculation and accumulation on the B vector to obtain an accumulated front-end channel alignment magnitude-phase vector C:
C＝[c1 c2…cm…cn] (3)
the normalized magnitude-phase vector D is obtained through calculation:
D＝C/|c1| (4)
from this, the vector E at the current angle at the current frequency is derived:
Figure BDA0003293863810000042
wherein D isHIs the conjugate transpose of vector D. The IQ value of the vector E is a table value corresponding to the n channels at the current angle at the current frequency.
When the database is obtained, under different frequencies in different directions of 0-360 degrees, the amplitude and the phase of n channels are calculated through formulas (1) - (5), a vector E is stored according to the rotation direction and the signal frequency of the direction-finding antenna to form a plurality of vectors E, and all the vectors E are synthesized into a correction table database E' through a conventional interpolation value smoothing algorithm.
When a certain direction is measured in real time, the PDW acquires imaginary real parts and corrected amplitudes of n channels, calculates a front-end channel alignment amplitude phase vector B' according to the formulas (1) and (2), indexes a vector E in a database according to PDW frequency calculated by the FPGA, and performs correlation operation on a certain angle d to obtain an evaluation value of the angle d:
fd＝B′EH (6)
where d is 0, 1, 2 … …, 360, evaluating values at all angles are calculated circularly, and the largest evaluating value f is founddThe corresponding direction is the direction finding result.
The invention reduces the inherent error of the channel through the multi-channel amplitude correction on the basis of the ultra-wideband single-bit receiver, fuses the signal amplitude and the phase information, fully utilizes the signal information received by each path of antenna array, collects data at a fixed angle, calculates the related vector to carry out smoothing and interpolation processing, generates a database, and carries out the related operation on the actually measured data and the database during direction finding to obtain the direction angle. The method has the advantages of effectively reducing inherent errors of system channels, along with high sensitivity, ultra-wide instantaneous bandwidth, small volume of the whole equipment, light weight, low cost and realization of higher direction finding precision with lower equipment quantity.

Claims (7)

1. An ultra-wideband correction amplitude-phase fusion direction finding method is characterized by comprising the following steps:
multichannel amplitude correction: correcting by using a fixed power point, obtaining n paths of received amplitude values under different powers after sweeping, fitting a curve, and taking the corresponding amplitude on the fitted curve as a calculation amplitude according to the signal power during direction finding to reduce the inherent amplitude error;
and (3) forming a breadth-phase fusion database: arranging a direction-finding antenna array on a rotary table, setting signal frequency, acquiring the amplitude and phase difference of radiation source signals with different directions of 0-360 degrees, calculating according to n channels to form characteristic vectors, storing the characteristic vectors according to the rotation direction and the signal frequency of the direction-finding antenna, processing by an interpolation value smoothing algorithm, and finally forming a correction table database;
database-based direction finding: when a certain direction is measured in real time, acquiring imaginary real parts and corrected amplitudes of n channels, calculating to obtain a front-end channel alignment amplitude-phase vector, indexing to a characteristic vector in a database according to frequency, calculating complex numbers and performing modulus on all angles, and searching for an azimuth corresponding to the maximum value, wherein the azimuth is a direction finding result.
2. The ultra-wideband calibration amplitude-phase fusion direction-finding method according to claim 1, wherein the direction-finding antenna array is composed of n directional antennas in a circular array, and the center pointing included angles of any two adjacent antenna beams are consistent.
3. The ultra-wideband correction amplitude-phase fusion direction-finding method as claimed in claim 1, wherein the formation of the amplitude-phase fusion database specifically comprises the following steps:
setting signal frequency and obtaining imaginary parts q of PDW of n channelsmReal part imOriginal amplitude ori _ ampmThe phase atan2 (q) is obtained from the imaginary real partm,im)，
Calculating a front-end amplitude-phase vector A:
front end amplitude phase vector A ═ a1 a2 … am … an] (1)
Wherein the m-th path of IQ data am＝{am.i,am.q}，am.i＝ampm*cos(atan2(qm,im))，am.q＝ampm*sin(atan2(qm,im))；
Calculating a front-end one-channel alignment magnitude-phase vector B:
Figure FDA0003293863800000011
wherein the content of the first and second substances,
Figure FDA0003293863800000012
and (3) for IQ data conjugation of the channel 1, carrying out multiple calculation and accumulation on the B vector to obtain an accumulated front-end channel alignment magnitude-phase vector C:
C＝[c1 c2 … cm … cn] (3)
the normalized magnitude-phase vector D is obtained through calculation:
D＝C/|c1| (4)
from this, the vector E at the current angle at the current frequency is derived:
Figure FDA0003293863800000021
wherein D isHIs the conjugate transpose of vector D; the IQ value of the vector E is a table value corresponding to n channels at the current angle under the current frequency;
under different frequencies in different directions of 0-360 degrees, the amplitude and phase of n paths of channels are calculated through formulas (1) - (5), a vector E is stored according to the rotation direction and the signal frequency of the direction-finding antenna to form a plurality of vectors E, and all the vectors E are synthesized into a correction table database E' through an interpolation value smoothing algorithm.
4. The ultra-wideband correction amplitude-phase fusion direction-finding method as claimed in claim 1, wherein the amplitude-phase fusion database is formed, and in the direction-finding based on the database, the complex calculation formula corresponding to the angle d is:
fd＝B′EH
b' is a front-end channel alignment amplitude-phase vector during real-time measurement, and the PDW frequency calculated by E indexes a characteristic vector in a database.
5. An ultra-wideband correction amplitude-phase fusion direction-finding system is characterized by comprising a correction source, an upper computer, an FPGA, a receiver and a rotary table;
the correction source is connected with a signal of an upper computer and is connected with a transmitting antenna as a radiation source;
the turntable is in signal connection with an upper computer, controls the orientation of the receiver and is used for acquiring the amplitude and phase difference of radiation source signals in different orientations of 0-360 degrees;
the FPGA is connected with an upper computer through a serial port and transmits a real-time processing result to the upper computer; the FPGA firstly corrects the multichannel amplitude, and the corresponding amplitude on the fitting curve is taken as the calculated amplitude according to the signal power during direction finding; then obtaining the amplitude and phase difference of the radiation source signals in different directions of 0-360 degrees, calculating according to n channels to form characteristic vectors, storing the characteristic vectors according to the rotating directions and signal frequencies of the direction-finding antenna, processing through an interpolation smoothing algorithm, and finally generating a correction table database; and during real-time direction finding, acquiring imaginary real parts and corrected amplitudes of the n channels, calculating to obtain an alignment amplitude-phase vector of a front-end channel, indexing to a characteristic vector in a database according to frequency, calculating complex numbers and performing modulus on all angles, and searching an azimuth corresponding to the maximum value as a direction finding result.
6. The ultra-wideband correction amplitude-phase fusion direction-finding system according to claim 5, wherein the specific process of generating the correction table database by the FPGA is as follows:
obtaining imaginary parts q of PDW of n channelsmReal part imOriginal amplitude ori _ ampmThe phase atan2 (q) is obtained from the imaginary real partm,im)，
Calculating a front-end amplitude-phase vector A:
front end amplitude phase vector A ═ a1 a2 … am … an] (1)
Wherein the m-th path of IQ data am＝{am.i,am.q}，am.i＝ampm*cos(atan2(qm,im))，am.q＝ampm*sin(atan2(qm,im))；
Calculating a front-end one-channel alignment magnitude-phase vector B:
Figure FDA0003293863800000031
wherein the content of the first and second substances,
Figure FDA0003293863800000032
and (3) for IQ data conjugation of the channel 1, carrying out multiple calculation and accumulation on the B vector to obtain an accumulated front-end channel alignment magnitude-phase vector C:
C＝[c1 c2 … cm … cn] (3)
the normalized magnitude-phase vector D is obtained through calculation:
D＝C/|c1| (4)
from this, the vector E at the current angle at the current frequency is derived:
Figure FDA0003293863800000033
wherein D isHIs the conjugate transpose of vector D; the IQ value of the vector E is a table value corresponding to n channels at the current angle under the current frequency;
under different frequencies in different directions of 0-360 degrees, the amplitude and the phase of n paths of channels are calculated through formulas (1) - (5), a vector E is stored according to the rotation direction and the signal frequency of the direction-finding antenna to form a plurality of vectors E, and all the vectors E are synthesized into a correction table database through an interpolation value smoothing algorithm.
7. The ultra-wideband correction amplitude-phase fusion direction-finding system according to claim 5, wherein the specific process of generating the correction table database by the FPGA is as follows: the complex calculation formula is:
fd＝B′EH
b' is a front-end channel alignment amplitude-phase vector during real-time measurement, and the PDW frequency calculated by E indexes a characteristic vector in a database.
CN202111172561.6A 2021-10-05 2021-10-05 Ultra-wideband correction amplitude-phase fusion direction finding method and system Pending CN113985345A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114609579A (en) * 2022-03-23 2022-06-10 电子科技大学 Defocusing direction finding error correction method
CN114839587A (en) * 2022-03-25 2022-08-02 中国电子科技集团公司第二十九研究所 External correction method for interferometer system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114609579A (en) * 2022-03-23 2022-06-10 电子科技大学 Defocusing direction finding error correction method
CN114839587A (en) * 2022-03-25 2022-08-02 中国电子科技集团公司第二十九研究所 External correction method for interferometer system
CN114839587B (en) * 2022-03-25 2023-09-05 中国电子科技集团公司第二十九研究所 External correction method for interferometer system

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