Beam correction method for digital emission array

Abstract

The invention discloses a beam correction method for a digital emission array, which comprises the following steps of: based on an automatic external correction means, measuring amplitudes and phase information correspondingly output by all test channels under different D / A excitation code values, and forming a correction table; and calling the correction table to obtain a D / A excitation code value of a full test channel, and correcting a phase weighted value according to a phase value in the correction table so as to correct a wave beam. According to the invention, the amplitude-phase error introduced by link nonlinearity can be effectively solved, the influence of hardware difference between channels can be eliminated, the shaping precision is greatly improved, and the power amplifier does not need to integrally back by 5-10dB, so that the equivalent radiation power of the array plane can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of digital phased arrays, and in particular to a beam correction method for a digital transmit array. Background Art

[0002] Digital aperture technology realizes phase shift and beamforming digitally, and has the advantage of flexible beam compared with analog phased arrays, and has been widely used. With the rapid development of aerospace technologies such as Internet communication satellites, the requirements for the functions and performance of the system are getting higher and higher. Compared with the past, the Internet satellite constellation and its payload subsystems have put forward more complex functions and very demanding performance requirements, especially the ability to transmit shaped beams.

[0003] As Figure 1 shown in the block diagram of a typical digital transmit array. Transmit beam shaping requires adjusting the amplitude and phase between each channel, which means that there must be specific differences in the output amplitude and phase of each channel. Since the D / A and power amplifiers in the digital array are non-linear devices, it is more complex than traditional in-phase correction. Conventional transmit arrays usually use deep saturation excitation to achieve the highest power amplifier efficiency for maximum power radiation. However, to meet the transmit shaping weighting, the saturation operating point is usually overall backed off by 5-10 dB and then the D / A excitation amplitude and phase weight values are adjusted. This backing off not only causes power waste, but also reduces the power amplifier efficiency, significantly reducing the equivalent radiated power of the system.

[0004] Furthermore, since the power amplifier itself is a non-linear device, even after the excitation is backed off, there are still differences in the transmit link gain with the change of the excitation power, and there will also be phase deviations. As Figure 2 and Figure 3 shown in the measured situation of a certain power amplifier chip.

[0005] In addition, the gain consistency of power amplifier chips between individuals deteriorates significantly in the non-saturation region compared with the saturation region, and there are amplitude and phase errors in the transmit links between different channels. Therefore, these two factors will further increase the difference between the actual amplitude and phase output of the array channels and the expected transmit weights, so the beam effect will be greatly reduced, resulting in problems such as poor beam shaping effect, pointing deviation, and sidelobe elevation.

[0006] In the existing related technologies involving emission correction, such as Patent CN110492917B, a fully digital beamforming array and a method for realizing automatic calibration of the amplitude and phase of the transceiver channels are proposed. A coupling line on the antenna array is used to realize the transceiver correction loop. In this method, a transmission line is embedded on the aperture surface of the antenna array, and calibration transceiver channels are connected to both ends of the transmission line. During emission calibration, each emission channel is sequentially excited, and at the same time, the amplitude and phase values of the signals sampled by the two calibration receiving channels are recorded. The amplitude and phase differences of all emission channels relative to the reference channel can be calculated. During reception calibration, all receiving channels of the system are in the working state, and the calibration emission channels on both sides are successively excited, and the amplitude and phase values of the calibration signals sampled by all receiving channels are recorded. The amplitude and phase differences of all receiving channels relative to the reference channel can be deduced.

[0007] Patent Application CN119363259A proposes a fast correction method based on phase coding. This method obtains the amplitude and phase of each channel by performing phase coding on all channels of the antenna, meeting the requirements of fast and high-precision calibration of the phased array antenna. During the calibration process, all T / R channels are working normally. The digital phase shifters in the components are used as encoders to perform phase coding on the signals of each channel. Finally, the measured complex signal sequence after coding is decoded. After deducting the amplitude and phase differences caused by the path from each channel to the test probe, the amplitude and phase signals of each T / R channel are obtained, and the antenna calibration is completed. This method can perform fast amplitude and phase correction on each T / R channel.

[0008] The above two methods mainly focus on the amplitude and phase consistency test of the emission and reception channels of the array, and then compensate for the amplitude and phase according to the consistency test results, but they cannot solve the problems of back-off and nonlinearity introduced by unequal amplitude addition weighting in emission.

[0009] Patent CN107132427B proposes a near-field signal test method and device for a phased array antenna in a saturated working state. After respectively performing weighting processing on the measured amplitude and measured phase data of each channel, the measured amplitude value and measured phase value of each channel are obtained; according to the measured amplitude values and phase values of each channel, the amplitude difference corresponding to the target amplitude value and the phase difference corresponding to the target phase value are respectively formed; it is judged whether the amplitude difference and the phase difference meet the condition for ending the iteration, so as to judge whether it is necessary to perform weighting processing on the measured amplitude value and measured phase value of each channel according to the amplitude difference and the phase difference to complete the iterative processing; after actually completing the iterative processing of each channel's data, the measured amplitude value and phase value of each channel of the antenna are obtained.

[0010] This method realizes the convergence of the weighting coefficient through iterative weighting value and near-field amplitude-phase extraction under near-field conditions. However, its implementation is relatively complex. After changing the weighting value in each iteration, a new round of near-field amplitude-phase extraction is required. Moreover, when the number of channels is large, the number of iterations will increase, and the test workload will increase significantly. Summary of the Invention

[0011] To solve the problems that the digital transmit array has a large power loss after the operating point retreats, and due to the nonlinearity of devices such as power amplifiers and the amplitude-phase errors of the link after the retreat, the final weighting error is too large, affecting the quality of the transmit beam, etc., the present invention proposes a beam correction method for a digital transmit array, which can improve the equivalent radiated power, improve the beam performance, and is easy to implement through automatic testing.

[0012] The technical solution adopted by the present invention is as follows:

[0013] A beam correction method for a digital transmit array, comprising:

[0014] Based on an automatic external calibration means, measure the amplitude and phase information corresponding to the outputs of all test channels under different D / A excitation code values, and form a calibration table;

[0015] Obtain the D / A excitation code values of all test channels by calling the calibration table, and correct the beam by correcting the phase weighting value according to the phase values in the calibration table.

[0016] Further, the step of measuring the amplitude and phase information corresponding to the outputs of all test channels under different D / A excitation code values based on the automatic external calibration means and forming a calibration table includes:

[0017] Build a test environment and perform initialization settings;

[0018] Simultaneously sample the first test channel and the excitation DDS reference signal to obtain the test channel data and reference channel received data at the corresponding coordinate points, and calculate the amplitude value of the test channel and the phase value relative to the reference channel;

[0019] Adjust the output amplitude code value of the first test channel according to a preset step, calculate the amplitude and phase values and form a calibration table, and each D / A excitation code value corresponds to an amplitude and a phase;

[0020] When the data acquisition of the first test channel is completed, perform the data acquisition of the next test channel until all test channels are traversed.

[0021] Further, the building of the test environment includes: placing the transmitting probe at a preset distance from the digital transmitting array surface, and keeping the scanning frame plane where the transmitting probe is located parallel to the digital transmitting array surface; adjusting the transmitting probe to align with the antenna normal direction of the first test channel and connecting it to a common test channel.

[0022] Further, the value range of the preset distance at which the transmitting probe is placed from the digital transmitting array surface includes: 3λ to 10λ, where λ is the wavelength corresponding to the lowest frequency required for the test.

[0023] Further, the initialization settings include: after the scanning frame where the transmitting probe is located moves into place, sending a trigger signal to the host computer, and the host computer controls the digital transmitting array surface to turn on the first test channel, configuring the D / A excitation code value, setting the initial phase to 0, and turning off the power amplifiers and D / A outputs of the remaining test channels.

[0024] Further, the obtaining of the test channel data and reference channel received data corresponding to the coordinate points includes:

[0025] Calculating the test channel data S test _N(n exci_i ,f j );

[0026] Calculating the reference channel received data S ref_ N(n exci_i ,f j );

[0027] Where N represents the test channel number, n exci_ is the i-th excitation code value of test channel N, and f j represents the current test frequency.

[0028] Further, the calculating of the amplitude value of the test channel includes:

[0029] Amp_N(n exci_i ,f j ) = 20 * log10(abs(f j S test _N(n exci_i ,f j )))

[0030] Where f j S test _N(n exci_i ,f j ) is the complex value at the frequency point f test _N(n exci_i ,f j ) after performing a fast Fourier transform on the test channel received signal S j at the frequency point f

[0031] Further, calculating the phase value of the test channel relative to the reference channel includes:

[0032]

[0033] where f j S ref_ N(n exci_i , f j ) is the complex value at the frequency point f j S ref_ N(n exci_i , f j ) after performing a fast Fourier transform on the reference signal f j .

[0034] Further, when the data acquisition of the first test channel is completed, performing the data acquisition of the next test channel includes: the host computer sending a trigger signal to the scanning frame, and the scanning frame adjusting the transmitting probe to align the normal direction of the antenna of the next test channel, and continuing to perform the data acquisition of the next test channel.

[0035] Further, obtaining the D / A excitation code values of all test channels by calling the calibration table and correcting the phase weighting values according to the phase values in the calibration table includes:

[0036] Based on the transmission weighting table, finding the test channel number K with the largest amplitude at the target frequency, and configuring its excitation code value according to the saturation output so that the amplitude value of Amp_K reaches the maximum;

[0037] Based on the amplitude difference delta_Amp between the shaping weights, performing a look-up table mapping according to the required output amplitude Amp_K - delta_Amp of each channel to obtain the excitation code values of the remaining N - 1 test channels respectively;

[0038] After obtaining the excitation code values of all N test channels, indexing the phase values Phi corresponding to the N test channels according to the calibration table, and the actual phase weighting coefficient of the test channel after phase correction is Phi_weight - Phi.

[0039] The beneficial effects of the present invention are as follows:

[0040] Based on the automatic external calibration means, the present invention measures the amplitude and phase information corresponding to the outputs of all channels under different D / A excitation code values. Since the external calibration means is adopted, the consistency differences between channels are also measured. During use, the excitation code values of all channels are obtained by calling the calibration table, and the phase weighting values are corrected according to the phase values in the table. The present invention can effectively solve the amplitude-phase errors introduced by link non-linearity and simultaneously eliminate the influence of hardware differences between channels, greatly improving the shaping accuracy. Moreover, the power amplifier no longer needs to be overall backed off by 5 - 10 dB, so the equivalent radiated power of the array surface can also be greatly increased.

[0041] From the perspective of the test comparison results, under the same shaping weight values, the method of the present invention significantly improves the quality of the transmitting beam, greatly improves the sidelobes, and effectively reduces the interference of the transmitting beam to the non-covered airspace. Description of the Drawings

[0042] Figure 1 is a block diagram of a typical digital transmitting array.

[0043] Figure 2 is one of the test result diagrams of a typical transmitting channel (gains at different excitation points).

[0044] Figure 3 is the second test result diagram of a typical transmitting channel (phases at different excitation points).

[0045] Figure 4 is a flowchart of a beam correction method for a digital transmitting array according to Embodiment 1 of the present invention.

[0046] Figure 5 is a schematic diagram of a beam correction method for a digital transmitting array according to Embodiment 1 of the present invention.

[0047] Figure 6 is a flowchart for error correction according to the calibration table in Embodiment 1 of the present invention.

[0048] Figure 7 is the radiation pattern of transmitting beam 1 before and after calibration.

[0049] Figure 8 is the radiation pattern of transmitting beam 2 before and after calibration.

[0050] Figure 9 is the radiation pattern of transmitting beam 3 before and after calibration. Detailed Embodiments

[0051] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0052] Embodiment 1

[0053] This embodiment provides a beam correction method for a digital transmit array, including:

[0054] Based on automatic external calibration means, measure the amplitude and phase information corresponding to the outputs of all test channels at different D / A excitation code values, and form a calibration table;

[0055] Obtain the D / A excitation code values of all test channels by calling the calibration table, and correct the beam by correcting the phase weighting values according to the phase values in the calibration table.

[0056] As Figure 4 shown, based on automatic external calibration means, measure the amplitude and phase information corresponding to the outputs of all test channels at different D / A excitation code values, and form a calibration table, including:

[0057] Build a test environment and perform initialization settings;

[0058] Simultaneously sample the first test channel and the excitation DDS reference signal to obtain the test channel data and reference channel received data of the corresponding coordinate points, and calculate the amplitude value of the test channel and the phase value relative to the reference channel;

[0059] Adjust the output amplitude code value of the first test channel according to a preset step (for example, it can be stepped according to an equivalent 0.1 dB excitation amplitude, and the optimal selection needs to be made according to the test effect), calculate the amplitude and phase values and form a calibration table, as shown in Table 1, each D / A excitation code value corresponds to an amplitude and a phase;

[0060] When the data acquisition of the first test channel is completed, perform the data acquisition of the next test channel until all test channels are traversed.

[0061] Table 1 - Calibration Table

[0062] Channel number (excitation code, frequency) Output power (excitation code, frequency) Output phase (excitation code, frequency) <![CDATA[Chanel_1n exci_1 ,f j )]]> <![CDATA[Amp_1n exci_1 ,f j )]]> <![CDATA[Phi_1n exci_1 ,f j )]]> <![CDATA[Chanel_1n exci_2 ,f j )]]> <![CDATA[Amp_1n exci_2 ,f j )]]> <![CDATA[Phi_1n exci_2 ,f j )]]> ... ... ... <![CDATA[Chanel_1n exci_I ,f j )]]> <![CDATA[Amp_1n exci_I ,f j )]]> <![CDATA[Phi_1n exci_I ,f j )]]>

[0063] Preferably, building a test environment includes: As Figure 4As shown in the figure, place the transmitting probe at a preset distance from the digital transmitting array surface, and keep the scanning frame plane where the transmitting probe is located parallel to the digital transmitting array surface; adjust the transmitting probe to align with the antenna normal of the first test channel and connect it to a common test channel.

[0064] Specifically, the preset distance range for placing the transmitting probe from the digital transmitting array surface can be 3λ to 10λ, where λ is the wavelength corresponding to the lowest frequency required for the test.

[0065] Preferably, the initialization settings include: after the scanning frame where the transmitting probe is located moves into place, send a trigger signal to the host computer, and the host computer controls the digital transmitting array surface to turn on the first test channel, configure the D / A excitation code value, set the initial phase to 0, and turn off the power amplifiers and D / A outputs of the remaining test channels.

[0066] Preferably, obtaining the test channel data and reference channel received data for the corresponding coordinate points includes:

[0067] Calculating the test channel data S test _N(n exci_i ,f j );

[0068] Calculating the reference channel received data S ref_ N(n exci_i ,f j );

[0069] Where N represents the test channel number, n exci_i is the i-th excitation code value of test channel N, and f j represents the current test frequency.

[0070] Preferably, calculating the amplitude value of the test channel includes:

[0071] Amp_N(n exci_i ,f j ) = 20 * log10(abs(f j S test _N(n exci_i ,f j )))

[0072] Where f j S test _N(n exci_i ,f j ) is the complex value at the frequency point f test _N(n exci_ ,f j ) after performing a fast Fourier transform on the test channel received signal S j at the frequency point f.

[0073] Preferably, calculating the phase value of the test channel relative to the reference channel includes:

[0074]

[0075] where f j S ref_ N(n exci_ , f j ) is the complex value at the frequency point f j S ref_ N(n exci_ , f j ) after performing a fast Fourier transform on the reference signal f j .

[0076] Preferably, after the data acquisition of the first test channel is completed, the data acquisition of the next test channel is performed, including: the host computer sends a trigger signal to the scanning frame, and the scanning frame adjusts the transmitting probe to align the normal direction of the antenna of the next test channel, and continues to perform the data acquisition of the next test channel.

[0077] Preferably, as Figure 6 shown, obtaining the D / A excitation code values of all test channels by calling the calibration table, and correcting the phase weighting values according to the phase values in the calibration table, including:

[0078] Based on the transmit weighting table, find the test channel number K with the largest amplitude at the target frequency, and configure its excitation code value according to the saturation output to make the amplitude value of Amp_K reach the maximum;

[0079] Based on the amplitude difference delta_Amp between the shaping weights, perform a look-up table mapping according to the required output amplitude Amp_K - delta_Amp of each channel to obtain the excitation code values of the remaining N - 1 test channels respectively (if the granularity of the calibration table is not enough, interpolation can be used for refinement);

[0080] After obtaining the excitation code values of all N test channels, index the phase values Phi corresponding to the N test channels according to the calibration table, and the actual phase weighting coefficient of the test channel after phase correction is Phi_weight - Phi.

[0081] In order to fully verify the effect of the beam correction method in this embodiment, three shaping beams of a 128-element fully digital transmit array were tested and compared. Before the above correction, the sidelobes of its transmit shaping beam were relatively high, causing a certain interference to the area outside the beam coverage area. The beam comparison results before and after correction are as Figures 7 - 9 shown.

[0082] From Figures 7 - 9From the comparison effect, under the same shaping weights, the quality of the transmitting beam is significantly improved, the sidelobes are greatly improved, and the interference of the transmitting beam to the non-covered airspace is effectively reduced.

[0083] Embodiment 2

[0084] This embodiment is based on Embodiment 1:

[0085] This embodiment provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the beam correction method for a digital transmit array in Embodiment 1. Among them, the computer program can be in the form of source code, object code, executable file or some intermediate form, etc.

[0086] Embodiment 3

[0087] This embodiment is based on Embodiment 1:

[0088] This embodiment provides a computer-readable storage medium, storing a computer program, and when the computer program is executed by a processor, it implements the beam correction method for a digital transmit array in Embodiment 1. Among them, the computer program can be in the form of source code, object code, executable file or some intermediate form, etc. The storage medium includes: any entity or device that can carry the computer program code, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the storage medium does not include electrical carrier signals and telecommunication signals.

[0089] It should be noted that for the foregoing method embodiments, for the sake of simple description, they are expressed as a series of action combinations. However, those skilled in the art should know that this application is not limited by the described action sequence, because according to this application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

Claims

1. A beam correction method for a digital transmit array, characterized in that: include: Based on automatic external correction, the amplitude and phase information of the corresponding output of all test channels under different D / A excitation code values ​​are measured, and a correction table is formed; The D / A excitation code values ​​of all test channels are obtained by calling the correction table, and the phase weighted value is corrected according to the phase value in the correction table, so as to correct the beam.

2. A beam correction method for a digital transmit array according to claim 1, characterized in that: The automatic external correction method measures the amplitude and phase information of the corresponding outputs of all test channels under different D / A excitation code values, and forms a correction table, including: Build a test environment and perform initial settings; The first test channel and the excitation DDS reference signal are sampled simultaneously to obtain the test channel data and the reference channel receiving data of the corresponding coordinate points, and the amplitude value of the test channel and the phase value relative to the reference channel are calculated; Adjust the output amplitude code value of the first test channel according to the preset step, calculate the amplitude and phase values ​​and form a correction table, each D / A excitation code value corresponds to an amplitude and phase; When the data collection of the first test channel is completed, the data collection of the next test channel is executed until all the test channels are traversed.

3. A beam correction method for a digital transmit array according to claim 2, characterized in that: The test environment is constructed by placing a transmitting probe at a preset distance from a digital transmitting array, keeping the scanning frame plane where the transmitting probe is located parallel to the digital transmitting array; adjusting the transmitting probe to align with the antenna normal of the first test channel and connecting it to a public test channel.

4. A beam correction method for a digital transmit array according to claim 3, characterized in that: The preset distance value range of the transmitting probe placed on the digital transmitting array plane includes: 3λ~10λ, wherein λ is the wavelength corresponding to the lowest frequency required for the test.

5. A beam correction method for a digital transmit array according to claim 2, characterized in that: The initialization setting includes: after the scanning frame where the transmitting probe is located moves into place, a trigger signal is sent to the upper computer, the upper computer controls the digital transmitting array to open the first test channel, configures the D / A excitation code value, configures the initial phase to 0, and shuts off the power amplifiers and D / A outputs of the remaining test channels.

6. A beam correction method for a digital transmit array according to claim 2, characterized in that: The step of acquiring the test channel data and the reference channel receiving data of the corresponding coordinate points includes: Calculate the test channel data S of the corresponding coordinate point test _N(n exci_i ,f j ); Calculate the reference channel receiving data S corresponding to the coordinate point ref_ N(n exci_i ,f j ); Where N represents the test channel number, n exci_i is the i-th excitation code value of test channel N, f j Indicates the current test frequency.

7. A beam correction method for a digital transmit array according to claim 6, characterized in that: The calculating the amplitude value of the test channel comprises: Amp_N(n exci_i ,f j )=20*log10(abs(f j S test _N(n exci_i ,f j ))) Among them, f j S test _N(n exci_i ,f j ) is the test channel receiving signal S test _N(n exci_i ,f j ) after fast Fourier transform at frequency f j The complex value at .

8. A beam correction method for a digital transmit array according to claim 7, characterized in that: The step of calculating the phase value of the test channel relative to the reference channel comprises: Among them, f j S ref_ N(n exci_i ,f j ) is the reference signal f j S ref_ N(n exci_i ,f j ) after fast Fourier transform at frequency f j The complex value at .

9. A beam correction method for a digital transmit array according to claim 2, characterized in that: When the data collection of the first test channel is completed, the data collection of the next test channel is executed, including: the host computer sends a trigger signal to the scanning frame, the scanning frame adjusts the transmitting probe to align the transmitting probe with the antenna normal of the next test channel, and continues to execute the data collection of the next test channel.

10. A beam correction method for a digital transmit array according to claim 1, characterized in that: The method of acquiring the D / A excitation code values ​​of all test channels by calling the correction table and correcting the phase weighted value according to the phase value in the correction table includes: Based on the transmission weighting table, find the test channel number K with the largest amplitude at the target frequency, and configure its excitation code value according to the saturated output to maximize the amplitude value of Amp_K; Based on the amplitude difference delta_Amp between the shaping weights, a table lookup mapping is performed according to the output amplitude Amp_K-delta_Amp required by each channel to obtain the excitation code values ​​of the remaining N-1 test channels respectively; After all the excitation code values ​​of the N test channels are obtained, the phase values ​​Phi corresponding to the N test channels are indexed according to the correction table. After the phase correction, the actual phase weighting coefficient of the test channel is Phi_weight-Phi.

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