CN115575910A - Calibration system, device and calibration method for broadband target array - Google Patents
Calibration system, device and calibration method for broadband target array Download PDFInfo
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Abstract
The invention provides a calibration system, a device and a calibration method of a broadband target array, wherein the calibration system comprises a main control module, a digital signal processing module, a frequency conversion module and a quaternary antenna: the four-element antenna is connected with the frequency conversion module through a microwave cable, the frequency conversion module is connected with the digital signal processing module through the microwave cable and a serial port cable, and the digital signal processing module is connected with the main control module through an optical fiber to form a calibration system of the broadband target array. The invention independently finishes the calibration work of each working frequency point and instantaneous bandwidth in the large working bandwidth of the system, does not depend on a Lai Gaoduan instrument, overcomes the defect of long time consumption in the traditional calibration using frequency sweeping mode, and reduces the calibration time.
Description
Technical Field
The invention relates to the technical field of calibration of target array systems, in particular to a calibration system, a calibration device and a calibration method of a broadband target array, and particularly relates to an internal self-building calibration method and a calibration device of the broadband target array.
Background
The target array system is a system for simulating an aerial radio frequency target signal in a laboratory, and belongs to a key part of a radio frequency semi-physical simulation system. The radio frequency simulation test makes up the defects of full-digital simulation, can simulate the electromagnetic environment in the actual combat environment more vividly, and can check the performance condition of the radar guidance system in the actual combat more accurately. Therefore, the accuracy of the target array system simulation has an important influence on the performance of the assessment equipment.
The principle of the target array system for simulating the target position is mainly based on an amplitude gravity center formula provided by Boeing company, namely, the signal amplitude is respectively controlled according to the amplitude gravity center formula and three paths of signals with consistent phases are spatially synthesized. The accuracy of the target array system is limited by the amplitude-phase consistency of each signal. Therefore, in order to ensure the precision of the system for simulating the target position, calibration needs to be performed on the target array system, that is, the amplitude-phase consistency of each path of signal is calibrated.
The traditional target array calibration method mainly comprises a standard signal source, a vector network analyzer and a four-horn receiving antenna, and amplitude-phase and angle calibration is carried out on the target array antenna by adopting dot-frequency continuous waves through an interference principle. The method depends heavily on standard instruments, the system connection is complex, integration cannot be realized, and time consumption is quite long due to the fact that continuous waves are used as calibration signals.
Patent document CN104391187a discloses a calibration device and a calibration method for a multi-frequency-point antenna array, which includes the following steps: the calibration control management module is used for performing calibration control and data processing on the antenna array; the microwave signal source generates a calibration time antenna array microwave signal; a four-horn receiving antenna receives an antenna array radiation radio frequency signal; the receiver module receives signals radiated by the antenna and performs frequency mixing amplification; and the vector network analyzer compares the amplitude and the phase of the intermediate-frequency signal amplified by the receiver module. And according to the working frequency point of the tested equipment, carrying out initial value calibration, angle simulation precision measurement and initial value verification calibration on the antenna array so that the radio frequency output signals of the antenna array triple antennas meet the requirement of amplitude-phase consistency.
The patent document CN104391187a cannot substantially improve efficiency, has a high degree of dependence on equipment, and cannot achieve a truly low cost. Most importantly, the conventional method similar to the method cannot acquire absolute amplitudes and phases at various frequency points, which causes that the method cannot calibrate the instantaneous bandwidth of a target array, and causes that a target array system cannot simulate the current mainstream high-resolution imaging radar target.
Disclosure of Invention
In view of the defects in the prior art, the present invention aims to provide a calibration system, a device and a calibration method for a broadband target array.
The invention provides a calibration system of a broadband target array, which comprises a main control module, a digital signal processing module, a frequency conversion module and a quaternary antenna, wherein the main control module comprises:
the four-element antenna is connected with the frequency conversion module through a microwave cable, the frequency conversion module is connected with the digital signal processing module through the microwave cable and a serial port cable, and the digital signal processing module is connected with the main control module through an optical fiber to form a calibration system of the broadband target array.
Preferably, the main control module is used for calibration control, data storage and data processing of the target array;
and the data processing comprises the step of obtaining the instantaneous amplitude-phase characteristics of each antenna unit of the target array through the acquired signal time domain data.
Preferably, the digital signal processing module includes: the device comprises an optical fiber communication module, a channel compensation module, a data acquisition module and a signal generation module;
the optical fiber communication module is used for receiving a control instruction in real time, transmitting acquired data to the main control module and providing a reference signal;
the data acquisition module is used for simultaneously acquiring microwave signals received by the quaternary antenna;
the signal generation module is used for generating signals, and the signals comprise extremely narrow pulse signals with adjustable frequency, amplitude, modulation degree, pulse width and periodic parameters, variable frequency control parameters and microwave signals during calibration;
the channel compensation module is used for compensating the error of the channel.
Preferably, the frequency conversion module up-converts the input intermediate frequency signal to a radio frequency and down-converts the input radio frequency signal to an intermediate frequency.
Preferably, the quaternary antenna is used for receiving a radio frequency signal radiated by the target array during calibration;
the quaternary antenna is a plurality of dual-polarized horn antennas and can be switched according to the polarization direction of the array to be tested.
According to the calibration method of the broadband target array of the calibration system of the broadband target array, provided by the invention, before the target array in a microwave semi-physical simulation test is put into use, the frequency bands covered by the target array need to be sequentially calibrated, so that radio frequency signals output by a triple antenna of the target array meet the requirement of amplitude-phase consistency, and the calibration of the broadband target array comprises the following steps: calibrating a target array initial value and measuring a target array angle error;
the target array initial value calibration is to acquire each antenna link radiation signal of a target array, process a digital signal, analyze signal characteristics to obtain amplitude and phase, and generate a broadband initial value table according to the difference value of the amplitude and the phase of the antenna link radiation signal and a reference signal;
and the target array angle error measurement is to measure the target array triplet combination position loaded into the broadband initial value table, and obtain an actual combination angle value according to a theoretical combination angle and an angle error.
Preferably, the calibration steps of the initial amplitude and phase values of the target array are as follows:
step S1.1: dividing the digital-to-analog conversion output port of the frequency converter into two paths, wherein one path is connected with any input port of the frequency converter to provide a reference signal; one path is connected with the simulation system, and is sent to the antenna in the selected target array through the simulation system feed link and radiates outwards;
step S1.2: connecting the main control module with the simulation system by using the optical fiber, sending the frequency point to be calibrated currently and the position of the antenna in the target array to the simulation system by using the main control module, and gating the corresponding antenna by using the simulation system;
step S1.3: the main control module issues a control instruction, the digital signal processing module generates a very narrow pulse signal, and the very narrow pulse signal is transmitted to a channel corresponding to any input port of a frequency converter connected with the frequency conversion module through a channel corresponding to a digital-to-analog conversion output port of the frequency converter; one path of the signal passes through an antenna link of a target array system and transmits an extremely narrow pulse signal which introduces an amplitude error and a phase error corresponding to a current gating channel;
step S1.4: the extremely narrow pulse signals are subjected to down-conversion of corresponding intermediate-frequency extremely narrow pulse signals by the frequency conversion module, and then the digital signal processing module synchronously acquires the intermediate-frequency extremely narrow pulse signals and transmits the intermediate-frequency extremely narrow pulse signals to the main control module through the optical fiber communication module;
step S1.5: the master control module performs pulse matching filtering processing in a single pulse period on the intermediate-frequency extremely-narrow pulse signal of the current gating channel to obtain the amplitude and phase of the signal in the synthesized large bandwidth, further generates an amplitude-frequency characteristic curve and a phase-frequency characteristic curve in the synthesized large bandwidth, and records data;
step S1.6: the main control module carries out pulse train matched filtering processing within a single-frame signal length on the two collected intermediate-frequency extremely-narrow pulse signals to obtain amplitude and phase difference values of the corresponding signals, records data and simultaneously generates a currently calibrated antenna serial number and a completion mark;
step S1.7: judging whether the initial value calibration of all the target array antennas is finished, if so, triggering the step S1.8; if not, repeating the step S1.2 to the step S1.6;
step S1.8: and taking the amplitude value of the antenna radiation signal with the minimum difference value between the target array antenna and the reference signal amplitude value as a reference, generating a broadband initial value table and loading the table into a simulation system to finish the broadband amplitude-phase initial value calibration.
Preferably, the target array angle error measuring step is as follows:
step S2.1: connecting an output port corresponding to the digital-to-analog converter of the frequency converter with the simulation system, sending the output port to an antenna in the currently selected target array through a feed link of the simulation system through a control instruction, radiating the antenna outwards, and synthesizing a target position in space;
step S2.2: connecting a main control module with a simulation system, wherein the main control module sends the frequency point to be calibrated currently and the position of the synthetic target to the simulation system, and the simulation system gates a corresponding antenna according to an instruction;
step S2.3: the main control module sends a control instruction, an extremely narrow pulse signal is transmitted through an output port channel corresponding to the digital-to-analog converter of the frequency converter, and the quaternary antenna simultaneously receives radio frequency signals radiated by a corresponding target array;
step S2.4: the frequency is converted to intermediate frequency by the frequency conversion module, and the digital signal processing module synchronously collects the frequency and transmits the frequency to the main control module by the optical fiber module;
step S2.5: respectively carrying out pulse train matched filtering processing within the length of a single-frame signal on the received intermediate-frequency extremely-narrow pulse signal to obtain the distance from a synthetic position to two antennas, further obtaining a corresponding azimuth angle error and a corresponding pitch angle error, and generating a corresponding angle serial number and a completion mark;
step S1.7: judging whether all the target array angle error measurement is finished, if so, calibrating all the target array angle error measurement; if not, repeating the step S2.2 to the step S2.5.
The calibration device for the broadband target array comprises a calibration system for the broadband target array according to any one of claims 1 to 5.
Preferably, the calibration device of the broadband target array is mounted on a turntable in the simulation system, and is overlapped with the aperture plane of the quaternary antenna and the rotation center of the turntable, and the turntable can be rotated to the direction of the antenna to be calibrated through a control command.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention independently completes the calibration work of each working frequency point and the instantaneous bandwidth in the large working bandwidth of the system without using a Lai Gaoduan instrument, overcomes the defect of long time consumption of the traditional calibration using a frequency sweeping mode, and reduces the calibration time.
2. The invention adopts the synthesized extremely narrow pulse, achieves the effect of instantaneous broadband by a simple method, solves the problem that the instantaneous bandwidth expansion of the system is influenced by the sweep frequency stepping on the traditional calibration precision, and reduces the pressure of the AD hardware performance of the traditional receiver.
3. The invention has simple system structure, low cost and strong universality.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a schematic diagram illustrating a conventional antenna array calibration system.
Fig. 2 is a schematic diagram of the antenna array calibration system according to the present invention.
FIG. 3 is a schematic diagram of the components of the calibration system for the broadband target array of the present invention.
FIG. 4 is a schematic diagram of the channel self-calibration principle of the present invention.
FIG. 5 is a schematic diagram illustrating the calibration principle of the initial amplitude and phase values of the target array according to the present invention.
FIG. 6 is a schematic diagram of the calibration principle of the angular error of the target array according to the present invention.
Fig. 7 is a schematic diagram of the time-frequency domain characteristics of the synthesized extremely narrow pulse signal.
In fig. 7, the abscissa represents time and the ordinate represents frequency, where Δ f represents frequency step.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the concept of the invention. All falling within the scope of the present invention.
The invention can independently complete each working frequency point in the large working bandwidth of the system and the calibration work in the large instantaneous bandwidth. The method overcomes the dependence of the traditional calibration method on high-end instruments such as standard signal sources, vector network analyzers and the like, overcomes the defect of long time consumption in the traditional calibration method using a frequency sweep mode, and solves the problem that the instantaneous bandwidth expansion of the system is influenced by frequency sweep stepping in the traditional calibration precision. The antenna array calibration system corresponding to the conventional calibration method is shown in fig. 1, and the antenna array calibration system corresponding to the calibration method of the present invention is shown in fig. 2.
According to the calibration system of the broadband target array provided by the present invention, as shown in fig. 2 and fig. 3, the calibration system includes a main control module, a digital signal processing module, a frequency conversion module and a quaternary antenna:
the four-element antenna is connected with the frequency conversion module through a microwave cable, the frequency conversion module is connected with the digital signal processing module through the microwave cable and a serial port cable, and the digital signal processing module is connected with the main control module through an optical fiber to form a calibration system of the broadband target array.
The main control module is used for target array calibration control, data storage and data processing; and the data processing comprises the step of obtaining the instantaneous amplitude-phase characteristics of each antenna unit of the target array through the acquired signal time domain data.
The digital signal processing module includes: the device comprises an optical fiber communication module, a channel compensation module, a data acquisition module and a signal generation module; the optical fiber communication module is used for receiving a control instruction in real time, transmitting acquired data to the main control module and providing a reference signal; the data acquisition module is used for simultaneously acquiring microwave signals received by the quaternary antenna; the signal generation module is used for generating signals, and the signals comprise extremely narrow pulse signals with adjustable frequency, amplitude, modulation degree, pulse width and periodic parameters, variable frequency control parameters and microwave signals during calibration; the channel compensation module is used for compensating the error of the channel.
The digital signal processing module receives the control parameters, controls the corresponding channel to carry out signal acquisition and signal playing, and controls the frequency conversion module through a serial port according to the corresponding time sequence;
the frequency conversion module up-converts an input intermediate frequency signal to a radio frequency and down-converts the input radio frequency signal to an intermediate frequency. And signals received by the quaternary antenna are converted into intermediate frequency signals according to corresponding control instructions, sent to the digital signal processing module for processing, and sent to the main control module for amplitude measurement, phase measurement and broadband phase comparison processing to generate a system calibration table.
The quaternary antenna is used for receiving a target array radiation radio frequency signal during calibration; the quaternary antenna is a plurality of dual-polarized horn antennas and can be switched according to the polarization direction of the array to be tested.
According to the calibration method of the broadband target array of the calibration system of the broadband target array, provided by the invention, before the target array in a microwave semi-physical simulation test is put into use, the frequency bands covered by the target array need to be sequentially calibrated, so that radio frequency signals output by a triple antenna of the target array meet the requirement of amplitude-phase consistency, and the calibration of the broadband target array comprises the following steps: calibrating a target array initial value and measuring a target array angle error;
the target array initial value calibration is to acquire each antenna link radiation signal of a target array, process a digital signal, analyze signal characteristics to obtain amplitude and phase, and generate a broadband initial value table according to the difference value of the amplitude and the phase of the antenna link radiation signal and a reference signal; the calibration steps of the initial amplitude and phase values of the target array are as follows:
step S1.1: dividing the power of a digital-to-analog conversion output port of the frequency converter into two paths, wherein one path is connected with any input port of the frequency converter to provide a reference signal; one path is connected with the simulation system, and is sent to the antenna in the selected target array through the simulation system feed link and radiates outwards;
step S1.2: connecting the main control module with the simulation system by using the optical fiber, sending the frequency point to be calibrated currently and the position of the antenna in the target array to the simulation system by using the main control module, and gating the corresponding antenna by using the simulation system;
step S1.3: the main control module issues a control instruction, the digital signal processing module generates a very narrow pulse signal, and the very narrow pulse signal is transmitted to a channel corresponding to any input port of a frequency converter connected with the frequency conversion module through a channel corresponding to a digital-to-analog conversion output port of the frequency converter; one path of the signal passes through an antenna link of a target array system and transmits an extremely narrow pulse signal which introduces an amplitude error and a phase error corresponding to a current gating channel;
step S1.4: the extremely narrow pulse signals are subjected to down-conversion of corresponding intermediate-frequency extremely narrow pulse signals by the frequency conversion module, and then the digital signal processing module synchronously acquires the intermediate-frequency extremely narrow pulse signals and transmits the intermediate-frequency extremely narrow pulse signals to the main control module through the optical fiber communication module;
step S1.5: the master control module performs pulse matching filtering processing in a single pulse period on the intermediate-frequency extremely-narrow pulse signal of the current gating channel to obtain the amplitude and phase of the signal in the synthesized large bandwidth, further generates an amplitude-frequency characteristic curve and a phase-frequency characteristic curve in the synthesized large bandwidth, and records data;
step S1.6: the main control module carries out pulse train matched filtering processing within a single-frame signal length on the two collected intermediate-frequency extremely-narrow pulse signals to obtain amplitude and phase difference values of the corresponding signals, records data and simultaneously generates a currently calibrated antenna serial number and a completion mark;
step S1.7: judging whether the initial value calibration of all the target array antennas is finished, if so, triggering a step S1.8; if not, repeating the step S1.2 to the step S1.6;
step S1.8: and taking the amplitude value of the antenna radiation signal with the minimum difference value between the target array antenna and the reference signal amplitude value as a reference, generating a broadband initial value table and loading the table into a simulation system to finish the broadband amplitude-phase initial value calibration.
And the target array angle error measurement is to measure the target array triplet combination position loaded in the broadband initial value table, and obtain an actual combination angle value according to a theoretical combination angle and an angle error. The target array angle error measurement steps are as follows:
step S2.1: connecting an output port corresponding to the digital-to-analog converter of the frequency converter with the simulation system, sending the output port to an antenna in the currently selected target array through a feed link of the simulation system through a control instruction, radiating the antenna outwards, and synthesizing a target position in space;
step S2.2: connecting a main control module with a simulation system, wherein the main control module sends the frequency point to be calibrated currently and the position of the synthetic target to the simulation system, and the simulation system gates a corresponding antenna according to an instruction;
step S2.3: the main control module sends a control instruction, an extremely narrow pulse signal is emitted through an output port channel corresponding to the frequency converter digital-to-analog converter, and the quaternary antenna simultaneously receives radio frequency signals radiated by a corresponding target array;
step S2.4: the frequency is converted to intermediate frequency by the frequency conversion module, and the digital signal processing module synchronously collects the frequency and transmits the frequency to the main control module by the optical fiber module;
step S2.5: respectively carrying out pulse train matched filtering processing within the length of a single-frame signal on the received intermediate-frequency extremely-narrow pulse signal to obtain the distance from a synthetic position to two antennas, further obtaining corresponding azimuth angle error and pitch angle error, and generating a corresponding angle serial number and a completion mark;
step S1.7: judging whether all the target array angle error measurement is finished, if so, calibrating all the target array angle error measurement; if not, repeating the step S2.2 to the step S2.5.
The calibration device for the broadband target array comprises a calibration system for the broadband target array. The calibration device of the broadband target array is arranged on a rotary table in the simulation system, is superposed with the aperture surface of the quaternary antenna and the rotation center of the rotary table, and can rotate the rotary table to the direction of the antenna to be calibrated through a control command.
According to the calibrating device for the broadband target array, each module in the calibrating device responds to instruction scheduling of the main control module in real time, the digital signal processing module provides a reference signal and collects an echo signal, the main control module performs data processing, analysis and calculation to generate a three-dimensional error mapping table, amplitude and phase errors and synthetic angle errors of each antenna unit of a target system are finally obtained, after the channel compensation module compensates the errors, the spatial positions of simulated radiation targets of the radar semi-physical simulation system under different working frequencies and large instantaneous bandwidths are realized, and finally the detection of the detection, target tracking and other capabilities of the radar guidance system under different working frequencies is realized.
Specifically, the invention is realized by the following steps:
the method comprises the following steps: fixing a calibration device of a broadband target array on a flight turntable, wherein the mouth surface of a quaternary antenna is superposed with the rotation center of the turntable;
step two: the digital signal processing module simultaneously acquires four paths of intermediate frequency signals according to a four-channel synchronous acquisition algorithm; generating a narrow pulse signal with adjustable parameters such as frequency, amplitude, modulation degree, pulse width, period and the like by synthesizing a narrow pulse generating algorithm;
step three: the frequency conversion module carries out up-conversion and down-conversion of the five-path signals in real time according to the control instruction;
step four: the optical fiber module receives the control instruction in real time and transmits the acquisition signal to the main control module;
step five: the main control module obtains instantaneous amplitude-phase characteristics of each antenna unit of the target array by using the acquired signal time domain data according to an instantaneous bandwidth amplitude-phase frequency characteristic curve extraction algorithm; and obtaining accurate distance data to calculate the angle error according to a one-dimensional high-resolution signal processing algorithm.
Specifically, the workflow mechanism of the present invention is as follows:
firstly, the device is arranged on a flight turntable of a simulation system, and a main control module controls the flight turntable to point to the coordinate of an antenna array antenna to be measured;
then, for different test functions, the calibration is as follows: 1. performing power division on an output port 5 of the frequency conversion module, or performing power division on four paths, connecting channels 1-4, and completing self calibration; 2. or the output port 5 of the frequency conversion module is divided into two paths, one path provides a reference signal, and the other path is sent to a target array system and radiated outwards through an antenna to finish initial value calibration; 3. or directly sending the data to a target array system, and radiating the data outwards through an antenna to finish the angular error calibration;
then, the digital signal processing module connects the main control module with the simulation system through the optical fiber module, the main control module sends the frequency points to be calibrated and the positions of the antennas in the target array to the simulation system, and the simulation system adjusts the direction of the rotary table and gates the corresponding antennas according to instructions;
then, the main control module issues a control instruction, the control device emits and synthesizes an extremely narrow pulse signal through the channel 5, the control channel 1 collects a space radiation signal, and the control channel 2 collects a coupling signal through the channel 5; the signal is subjected to down-conversion by the frequency conversion module, is synchronously acquired by the digital signal processing module and is transmitted to the main control module by the optical fiber module;
finally, the main control module processes the acquired channel data to generate an amplitude-phase initial value and an angle error, and records the data; the main control module controls the working time sequence and information interaction of other modules in real time.
The invention is further described by way of example:
assuming that the frequency point of the target array to be calibrated is f C Instantaneous bandwidth of B, frequency range of f c -B/2～f c +B/2。
Firstly, calibrating the channel of the device, as shown in fig. 4, generating a very narrow pulse signal s (t) as follows:
f 0 ＝f c -B/2
wherein i represents the number of pulses, j represents an imaginary number, rect () represents a rectangular function, exp represents an exponential function, T represents time, τ represents the width of the transmitted pulse, T represents the number of pulses, and r representing the pulse repetition period of the signal, f 0 The carrier frequency starting frequency, B is the single sub-pulse width, N is the carrier frequency stepping number, and delta f is the carrier frequency stepping ladder. The time-frequency domain characteristics of the synthesized extremely narrow pulse signal are shown in fig. 7.
Controlling the digital signal processing module to generate the synthesized extremely narrow pulse signal, outputting the signal to the frequency conversion module through a channel 5, connecting the signal to frequency converter channels 1-4 through four paths of power distribution, and processing the signal by the digital signal processing module channel 14, collecting, transmitting to a main control module through an optical fiber communication module, and performing pulse compression processing on each sub-pulse of the synthesized extremely narrow pulse signal by the main control module to obtain a group of amplitude phases marked as F i ,A i ,φ i Wherein, i =0,1,2, … and n-1,n represent the number of sub-pulses of the synthesized extremely-narrow pulse signal, and finally the channel amplitude-phase-frequency characteristic table is obtained. As shown in table 1:
TABLE 1
| Number of pulses | 0 | 1 | 2 | n-1 | |
| Frequency of | F0 | F1 | F2 | …… | Fn-1 |
| Amplitude of | A0 | A1 | A2 | …… | An-1 |
| Phase position | φ1 | φ2 | φ3 | …… | φn-1 |
Taking channel 1 as an example, it is shown in table 2. The amplitude characteristic of the ideal channel is constant and the phase characteristic is linear. Therefore, an amplitude-phase-frequency compensation characteristic table can be obtained according to the amplitude-phase-frequency characteristic of the channel, and compensation filter coefficients { a1, a2, …, a (M + 1) } with the order M can be solved reversely in a channel intelligent algorithm such as a particle swarm algorithm, wherein M represents the order, and the number of FIR filter coefficients is the order +1. And the amplitude-phase characteristic calibration of each channel of the calibration device in the measured instantaneous bandwidth can be finished by loading the coefficient into a channel compensation module in the digital signal processing module.
TABLE 2
Then, after the self channel of the device is calibrated, the initial value calibration of the amplitude and phase of the target array is carried out, as shown in fig. 5, the output port 5 of the frequency converter of the device is divided into two paths, and one path is connected with the input port B of the frequency converter to provide a reference signal for the device; one path is connected with the simulation system, can be sent to the antenna in the selected target array through a simulation system feed link through a control command, and radiates outwards through the antenna;
one path of the signal is radiated and synthesized into a very narrow pulse signal through the device channel 5, namely the signal received by the channel 2 is as follows:
one path passes through an antenna link of the target array system, and amplitude-phase errors Ai and phi i are introduced, namely signals received by a channel 1 are as follows:
and the digital signal processing module uploads the two collected paths of data to the main control module. The main control module performs pulse compression processing on each sub-pulse signal in the same frame signal to obtain the amplitude-phase parameter sigma (F) of each stepping frequency point of the target array i ,A i ,φ i )；
The same frame of signals of the channel 1 and the channel 2 are subjected to pulse string compression processing to obtain a high-precision amplitude-phase parameter F of a test frequency point c Delta A, delta phi, after all antenna units of the target array are calibrated,
selecting the amplitude delta A _ min of the radiation signal with the minimum amplitude difference as a reference, and subtracting the amplitude delta A _ min from the amplitude difference of each antenna to obtain the final amplitude-phase parameter sigma (F) of all the antennas c Δ Ai- Δ A _ min, Δ φ i), which value, together with the initial value of the calibration for the target array at that frequency point, will be Σ (F [ + ]) i ,A i ,φ i ) Minus (F) c Δ a- Δ a _ min, Δ Φ) to obtain an amplitude-phase-frequency characteristic table within the instantaneous bandwidth of the target array with the test frequency point as the center and the bandwidth B, as shown in table 3, thereby obtaining a three-dimensional error mapping table, as shown in table 4:
TABLE 3
| Antenna serial number | Center frequency | Bandwidth of | Attenuation control value | |
| 1 | fs | B | ΔA1-ΔA_min | Δφ1 |
| 2 | fs | B | ΔA2-ΔA_min | Δφ2 |
| …… | …… | …… | …… | …… |
TABLE 4
Then, after loading the three-dimensional error mapping table into the simulation system, measuring and calibrating the angle error of the target array, as shown in fig. 6, using the same synthesized extremely narrow pulse signal as the transmitting signal,
connecting the output port 5 of the frequency converter of the device with a simulation system, transmitting the control instruction to the triple antenna in the selected target array through a feed link of the simulation system, radiating the control instruction outwards through the antenna, and synthesizing a target position in space;
the device receives signals radiated by the target array through a channel 1, a channel 2, a channel 3 and a channel 4. The digital signal processing module uploads the two collected paths of data to the main control module;
and the main control module performs pulse train compression processing on the same frame of signals in the channel 1 and the channel 2 to obtain distances R1 and R2 from the synthesized position to the antenna A and the antenna B. The azimuth error is calculated by the following formula:
θ＝arcsin((R2-R1)/d 1 )
where θ represents the azimuth error, d 1 Represents the spacing between the a and B antennas; similarly, the same frame signal in the channel 3 and the channel 4 is subjected to pulse train compression processing, and distances R3 and R4 from the combining position to the C antenna and the D antenna are obtained. And calculating a pitch angle error phi through a formula, wherein the calculation formula is as follows:
φ＝arcsin((R4-R3)/d 2 )
wherein, phi represents a pitch angle error, and D2 represents a distance between the C antenna and the D antenna;
and sequentially measuring actual synthetic angle errors of all triples of the target array to obtain a database of theoretical angle errors and actual measurement angle errors, and completing the angle error calibration of the target array.
The calibration method of the broadband target array can be realized only by a calibration device of the broadband target array, and the calibration cost is relatively low. Meanwhile, the traditional antenna array surface calibration method in the background technology depends on a standard instrument and generally cannot acquire absolute amplitude-phase-frequency characteristics in the target array instantaneous bandwidth, so that the calibration of the target array instantaneous bandwidth cannot be completed.
In the design research and development process of the invention, the data processing algorithm of the device main control module, the four-channel synchronous acquisition of the digital signal processing module and the generation method for synthesizing the extremely narrow pulse signal are designed more complicated, but the practical use is very convenient and efficient, the research and development cost is very low, the later maintenance is also relatively simple, and the universality is strong. The invention independently completes the calibration work of each working frequency point and instantaneous bandwidth in the large working bandwidth of the system through the self-built acquisition and analysis module in the device.
Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (10)
1. The calibration system of the broadband target array is characterized by comprising a main control module, a digital signal processing module, a frequency conversion module and a quaternary antenna:
the four-element antenna is connected with the frequency conversion module through a microwave cable, the frequency conversion module is connected with the digital signal processing module through the microwave cable and a serial port cable, and the digital signal processing module is connected with the main control module through an optical fiber to form a calibration system of the broadband target array.
2. The system for calibrating a broadband target array according to claim 1, wherein the main control module is configured to perform target array calibration control, store collected data, and perform data processing;
and the data processing comprises the step of obtaining the instantaneous amplitude-phase characteristics of each antenna unit of the target array through the acquired signal time domain data.
3. The system for calibrating a broadband target array according to claim 1, wherein the digital signal processing module comprises: the device comprises an optical fiber communication module, a channel compensation module, a data acquisition module and a signal generation module;
the optical fiber communication module is used for receiving a control instruction in real time, transmitting acquired data to the main control module and providing a reference signal;
the data acquisition module is used for simultaneously acquiring microwave signals received by the quaternary antenna;
the signal generating module is used for generating signals, and the signals comprise extremely narrow pulse signals with adjustable frequency, amplitude, modulation degree, pulse width and periodic parameters, variable frequency control parameters and microwave signals during calibration;
the channel compensation module is used for compensating the error of the channel.
4. The system for calibrating a broadband target array according to claim 1, wherein the frequency conversion module up-converts an input intermediate frequency signal to a radio frequency and down-converts an input radio frequency signal to an intermediate frequency.
5. The system for calibrating a broadband target array according to claim 1, wherein the quaternary antenna is configured to receive a calibration time target array radiated radio frequency signal;
the quaternary antenna is a plurality of dual-polarized horn antennas and can be switched according to the polarization direction of the array to be tested.
6. A method for calibrating a broadband target array of a calibration system for a broadband target array according to claim 1, wherein before a target array in a microwave semi-physical simulation test is put into use, frequency bands covered by the target array need to be sequentially calibrated, so that radio frequency signals output by a triple antenna of the target array meet the requirement of amplitude-phase consistency, and the broadband target array calibration comprises: calibrating a target array initial value and measuring a target array angle error;
the target array initial value calibration is to acquire each antenna link radiation signal of a target array, process a digital signal, analyze signal characteristics to obtain amplitude and phase, and generate a broadband initial value table according to the difference value of the amplitude and the phase of the antenna link radiation signal and a reference signal;
and the target array angle error measurement is to measure the target array triplet combination position loaded into the broadband initial value table, and obtain an actual combination angle value according to a theoretical combination angle and an angle error.
7. The method for calibrating a broadband target array of the calibration system for a broadband target array according to claim 6, wherein the step of calibrating the amplitude and phase initial values of the target array comprises the following steps:
step S1.1: dividing the power of a digital-to-analog conversion output port of the frequency converter into two paths, wherein one path is connected with any input port of the frequency converter to provide a reference signal; one path is connected with the simulation system, and is sent to the antenna in the selected target array through the simulation system feed link and radiates outwards;
step S1.2: connecting a main control module with a simulation system by using an optical fiber, sending the frequency point to be calibrated currently and the position of an antenna in a target array to the simulation system by using the main control module, and gating the corresponding antenna by using the simulation system;
step S1.3: the main control module issues a control instruction, the digital signal processing module generates a very narrow pulse signal, and the very narrow pulse signal is transmitted to a channel corresponding to any input port of a frequency converter connected with the frequency conversion module through a channel corresponding to a digital-to-analog conversion output port of the frequency converter; one path of the signal passes through an antenna link of a target array system and transmits an extremely narrow pulse signal which introduces an amplitude error and a phase error corresponding to a current gating channel;
step S1.4: the extremely narrow pulse signals are subjected to down-conversion of corresponding intermediate-frequency extremely narrow pulse signals by the frequency conversion module, and then the digital signal processing module synchronously acquires the intermediate-frequency extremely narrow pulse signals and transmits the intermediate-frequency extremely narrow pulse signals to the main control module through the optical fiber communication module;
step S1.5: the master control module performs pulse matching filtering processing in a single pulse period on the intermediate-frequency extremely-narrow pulse signal of the current gating channel to obtain the amplitude and phase of the signal in the synthesized large bandwidth, further generates an amplitude-frequency characteristic curve and a phase-frequency characteristic curve in the synthesized large bandwidth, and records data;
step S1.6: the main control module carries out pulse train matched filtering processing within the length of a single-frame signal on the two collected intermediate-frequency extremely-narrow pulse signals to obtain the amplitude and phase difference values of the corresponding signals, records data and generates the serial number of the currently calibrated antenna and a completion mark at the same time;
step S1.7: judging whether the initial value calibration of all the target array antennas is finished, if so, triggering the step S1.8; if not, repeating the step S1.2 to the step S1.6;
step S1.8: and taking the amplitude value of the antenna radiation signal with the minimum difference value between the target array antenna and the reference signal amplitude value as a reference, generating a broadband initial value table and loading the table into a simulation system to finish the broadband amplitude-phase initial value calibration.
8. The method for calibrating a broadband target array of the calibration system for a broadband target array according to claim 6, wherein the target array angular error measurement step is as follows:
step S2.1: connecting an output port corresponding to the digital-to-analog converter of the frequency converter with the simulation system, sending the output port to an antenna in the currently selected target array through a feed link of the simulation system through a control instruction, radiating the antenna outwards, and synthesizing a target position in space;
step S2.2: connecting a main control module with a simulation system, wherein the main control module sends the frequency point to be calibrated currently and the position of the synthetic target to the simulation system, and the simulation system gates a corresponding antenna according to an instruction;
step S2.3: the main control module sends a control instruction, an extremely narrow pulse signal is transmitted through an output port channel corresponding to the digital-to-analog converter of the frequency converter, and the quaternary antenna simultaneously receives radio frequency signals radiated by a corresponding target array;
step S2.4: the frequency is converted to intermediate frequency by the frequency conversion module, and the digital signal processing module synchronously collects the frequency and transmits the frequency to the main control module by the optical fiber module;
step S2.5: respectively carrying out pulse train matched filtering processing within the length of a single-frame signal on the received intermediate-frequency extremely-narrow pulse signal to obtain the distance from a synthetic position to two antennas, further obtaining corresponding azimuth angle error and pitch angle error, and generating a corresponding angle serial number and a completion mark;
step S1.7: judging whether all the target array angle error measurement is finished, if so, calibrating all the target array angle error measurement; if not, repeating the step S2.2 to the step S2.5.
9. A calibration device for a broadband target array comprising the calibration system for a broadband target array according to any one of claims 1 to 5.
10. The calibration device for the wideband target array according to claim 9, wherein the calibration device for the wideband target array is installed on a turntable in the simulation system, and the turntable can be turned to the direction of the antenna to be calibrated by the control command, and the turntable coincides with the aperture plane of the quaternary antenna and the rotation center of the turntable.
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