Phase calibration method, phase calibration device and storage medium

Abstract

The embodiment of the invention provides a phase calibration method, a phase calibration device and a storage medium, the phase calibration method is used for obtaining a phase step and a phase code table used for phase calibration of a phase shifter, and the phase calibration method comprises the following steps: presetting a first phase code table which comprises a plurality of phase codes, traversing a preset phase step combination by using the first phase code table to perform phase calibration, transmitting a preset waveform signal by using a calibrated phase code, judging whether the performance index of the preset waveform signal accords with a performance index threshold value or not, and taking the phase step combination of which the performance index accords with the performance index threshold value as an optimal phase step; and performing phase calibration on a plurality of groups of transmitting antennas by adopting the preferred phase step and one or more second phase code tables, and obtaining a third phase code table by taking part or all of phase codes obtained after the phase calibration of the plurality of groups of transmitting antennas. The optimal phase stepping is obtained by combining the waveform performance indexes, so that the transmitted waveform is closer to the expected waveform, and better calibration precision is obtained.

Description

Technical Field

[0001] This article relates to but is not limited to the field of radio frequency technology, and in particular to a phase calibration method, a phase calibration device and a storage medium. Background Art

[0002] Integrated circuit (IC), also known as chip, is a way to miniaturize circuits in electronics and is often manufactured on the surface of semiconductor wafers. A chip contains a bare die manufactured using semiconductor manufacturing processes and a packaging structure. The RF chip structure usually includes a phase shifter for adjusting the phase of the wave. The RF phase shifter has the function of adjusting the phase of the RF signal and is an important component of the RF and microwave transceiver system.

[0003] However, currently the calibration of phase shifters is limited by the environment. Summary of the invention

[0004] The embodiments of the present application provide a phase calibration method, a phase calibration device, and a storage medium, which can improve the phase output accuracy to adapt to the desired waveform signal.

[0005] On the one hand, an embodiment of the present application provides a phase calibration method for obtaining a phase step and a phase code table used for phase calibration of a phase shifter, comprising:

[0006] A first phase code table is preset, wherein the first phase code table includes a plurality of phase codes, the first phase code table is used to traverse a preset phase step combination for phase calibration, a preset waveform signal is transmitted using the calibrated phase code, and whether a performance index of the preset waveform signal meets a performance index threshold is determined, and a phase step combination whose performance index meets the performance index threshold is used as a preferred phase step;

[0007] The preferred phase stepping and one or more second phase code tables are used to perform phase calibration on multiple groups of transmitting antennas, and a third phase code table is obtained by taking part or all of the phase codes obtained after the phase calibration of the multiple groups of transmitting antennas.

[0008] On the other hand, an embodiment of the present application further provides a phase calibration method for performing phase calibration on a phase shifter output waveform, comprising:

[0009] The above phase calibration method is used to obtain the optimal phase step and the third phase code table;

[0010] A calibration command is generated according to the preferred phase stepping and the third phase code table to perform phase calibration on one or more antenna boards, wherein the antenna board includes a radar chip and a transmitting antenna connected to the radar chip.

[0011] On the other hand, an embodiment of the present application further provides a calibration device, including a processor and a memory storing a computer program executable on the processor, wherein the processor implements the steps of any of the aforementioned phase calibration methods when executing the program.

[0012] On the other hand, an embodiment of the present application further provides a non-transitory computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute any of the aforementioned phase calibration methods.

[0013] By adopting the method of this embodiment, the optimal phase step is obtained by combining the waveform performance index, so that the transmission waveform can be closer to the desired waveform and better calibration accuracy can be obtained. In addition, by separately determining the phase step and the phase code table, the calibration time can be shortened.

[0014] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by implementing the present application. Other advantages of the present application can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0016] Figure 1A This is a flow chart of a phase calibration method according to an embodiment of the present disclosure;

[0017] Figure 1B This is a flow chart of another phase calibration method according to an embodiment of the present disclosure;

[0018] Figure 2 A diagram of a calibration system for calibrating a radar chip according to an embodiment of the present disclosure;

[0019] Figure 3 The overall flow chart of calibrating the radar chip according to the embodiment of the present disclosure;

[0020] Figure 4 A flow chart for determining a preferred phase step for an embodiment of the present disclosure;

[0021] Figure 5 A flow chart for determining a preferred phase code table for an embodiment of the present disclosure;

[0022] Figure 6 A flow chart for calibrating other antenna panels for embodiments of the present disclosure;

[0023] Figure 7 This is a flow chart of phase calibration according to an embodiment of the present disclosure;

[0024] Figure 8 A schematic diagram of a radar transmission waveform according to an embodiment of the present disclosure;

[0025] Fig. 9 Schematic diagram of a calibration device according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0026] The present application describes multiple embodiments, but the description is exemplary rather than restrictive, and it is obvious to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described in the present application. Although many possible feature combinations are shown in the drawings and discussed in the specific embodiments, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0027] The present application includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features and elements disclosed in the present application may also be combined with any conventional features or elements to form a unique invention scheme defined by the claims. Any features or elements of any embodiment may also be combined with features or elements from other invention schemes to form another unique invention scheme defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in the present application may be implemented individually or in any appropriate combination. Therefore, except for the limitations made according to the attached claims and their equivalents, the embodiments are not subject to other restrictions. In addition, various modifications and changes may be made within the scope of protection of the attached claims.

[0028] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps of the specific order described. As will be understood by those of ordinary skill in the art, other sequences of steps are also possible. Therefore, the specific sequence of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to the steps of performing them in the order written, and those skilled in the art can easily understand that these sequences can be changed and still remain within the spirit and scope of the embodiments of the present application.

[0029] The DDM-MIMO (Doppler Division Multiplexing-Multiple-Input and Multiple-Output) waveform is a commonly used waveform for millimeter-wave radar in automotive scenarios. This waveform uses phase modulation between transmit pulses to separate channels in the Doppler domain to form multiple virtual channels. Under the DDM-MIMO waveform, the transmit signals are transmitted simultaneously, with high power, long target detection range, and a large speed unambiguous range (speed unambiguous means that the speed does not exceed the maximum speed range of the radar). However, the accuracy requirements for the transmission phase of the transmit signal are high. If the phase accuracy of the modulation during transmission is low, it is easy to cause large leakage and strong coupling between the transmit channels, which will lead to errors in the calculation of the transmission signal sequence, resulting in angle resolution errors.

[0030] To implement DDM-MIMO, phase shifters are used to adjust the phase of the input signal so that each sub-channel or filter can selectively process signals within different Doppler frequency shift ranges. Specifically, by adjusting the phase of different TX transmission chain phase shifters, the spectrum from different TX signals can be moved to different frequency ranges, and then the corresponding filters are used to separate and process the signals. In this way, each sub-channel or filter can specifically process the target signal within a specific Doppler frequency shift range.

[0031] Taking radar chips as an example, phase shifters are usually configured in the transmitting module and receiving module of the radar chip. The phase shifter can achieve phase control of the signal by adjusting the phase of its input signal. Specifically, the phase shifter controls the phase of the signal sent by the antenna through phase stepping. Different phase shifters have different phase step values, usually expressed in angles or bits. Selecting a suitable phase step value is very important for achieving the required phase adjustment accuracy and range. The inventors found that in the calibration of the phase shifter performed when the radar chip leaves the factory, there are usually fewer phase codes that support calibration, and the impact of DDM leakage is not considered. In addition, when the external environment changes, the phase code calibrated at the factory may no longer be suitable for the current application scenario.

[0032] To this end, the embodiment of the present disclosure provides a phase calibration method to calibrate the transmission phase. After the phase is calibrated by the implementation method, the DDM-MIMO waveform is transmitted using the calibrated transmission phase, which can reduce the leakage amplitude, reduce the coupling effect between TX channels, improve the angle measurement accuracy and reduce the angle error rate. It should be noted that the implementation method is not to calibrate the output phase of the phase shifter in order to improve the performance of the phase shifter, but to make the phase shifter output the DDM-MIMO waveform more accurately through calibration.

[0033] A phase calibration method provided by the embodiment of the present disclosure is as follows: Figure 1AAs shown, the method for obtaining the phase step and phase code table used for phase calibration of the phase shifter includes the following steps:

[0034] Step 10: preset a first phase code table, wherein the first phase code table includes a plurality of phase codes, use the first phase code table to traverse a preset phase step combination for phase calibration, use the calibrated phase code to transmit a preset waveform signal, determine whether a performance index of the preset waveform signal meets a performance index threshold, and use a phase step whose performance index meets the performance index threshold as a preferred phase step;

[0035] The first phase code table is an uncalibrated phase code table, which is a preset phase code table used to determine the preferred phase step. When the first phase code table is preset, since the preferred phase step cannot be selected yet, a phase code table containing the most phase codes can be selected as the first phase code table, or a phase code table that takes both performance and the number of phase codes into consideration can be selected, for example, a phase code table that does not have the most phase codes but has better performance can be selected, or other standards can be used for selection.

[0036] The preset waveform signal refers to a signal of a certain waveform that the transmitter is expected to emit. The waveform includes but is not limited to frequency modulated continuous wave (FMCW), Doppler diversity wave (DDM), pulse wave, etc. The performance index of the preset waveform refers to the parameter used to evaluate the performance of the preset waveform. For different waveforms, the evaluation index is different and can be set as needed.

[0037] Step 20: Use the preferred phase stepping and one or more second phase code tables to perform phase calibration on multiple groups of transmitting antennas, and obtain part or all of the phase codes obtained after the phase calibration of the multiple groups of transmitting antennas to obtain a third phase code table.

[0038] When performing phase calibration on multiple groups of transmitting antennas, one or more second phase code tables can be used for calibration. The second phase code tables used for calibration of different groups of transmitting antennas can be the same or different. In this step, the preferred phase step has been determined, so a phase code table containing a phase that is closer to the preferred phase step can be selected as the second phase code table according to the preferred phase step. For example, if the phase step is 90°, a phase code table containing a phase of 90±5° (here only for example) can be selected as the second phase code table. In some embodiments, the second phase code table can be the same as the first phase code table, that is, the same phase code table as in step 10 is selected for calibration. The purpose of calibration is to select a phase code that makes the output phase conform to the expected phase as an alternative phase code, and obtain a third phase code table as the preferred phase code table by synthesizing the alternative phase codes obtained after phase calibration of multiple groups of antennas. The output phase is the phase of the radio frequency signal transmitted by the transmitting antenna after phase shifting by the phase shifter, and the expected phase refers to the expected phase of the radio frequency signal. For example, the expected phase is 180°, and a phase code that enables the transmitting antenna to transmit a 180° phase signal is selected through phase calibration.

[0039] By adopting the method of this embodiment, the optimal phase step is obtained by combining the waveform performance index, so that the transmission waveform can be closer to the desired waveform and better calibration accuracy can be obtained. In addition, by separately determining the optimal phase step and the phase code table, the calibration time can be shortened.

[0040] In an exemplary embodiment, in the above step 10, the step of using the first phase code table to traverse the preset phase step combination for phase calibration may include: generating a preset phase step combination based on the number of transmitting antennas and the desired phase; when using the first phase code table to traverse the preset phase step combination for phase calibration, selecting a preset phase step combination from the preset phase step combination, and generating a phase calibration command according to the selected preset phase step combination, the phase code table and the target position to perform phase calibration until all preset phase step combinations are traversed.

[0041] Optionally, when performing phase calibration in step 10, a group of transmitting antennas located on the same chip may be phase calibrated, and a preferred phase step may be selected with reference to the result of the calibration of the group of transmitting antennas. Specifically, after calibration using different phase step combinations, each phase step combination will obtain a calibrated phase code, and a preset waveform signal is transmitted using the phase code, and a performance index of the preset waveform signal is calculated, and it is determined whether the obtained performance index meets the performance index threshold, and the phase step combination whose performance index meets the performance index threshold is used as the preferred phase step. For example, the phase step combination with the best performance index may be used as the preferred phase step.

[0042] In an exemplary embodiment, when the performance index of the preset waveform signal is better than the performance index threshold, the performance index threshold can be updated, and the performance index threshold is updated using the performance index of the preset waveform signal. In this way, the performance index threshold can be made the optimal value, and the phase step combination corresponding to the performance index threshold is used as the preferred phase step. The performance index threshold can be one or more. The above update includes but is not limited to modifying or replacing one or more performance index thresholds.

[0043] In an exemplary embodiment, taking the preset waveform as a DDM waveform as an example, the step of transmitting the preset waveform signal using the calibrated phase code and judging whether the performance index of the preset waveform signal meets expectations may include: transmitting the DDM waveform signal using the calibrated phase code and judging whether the DDM leakage level of the current DDM waveform signal is less than the preset minimum DDM leakage level, and the preset minimum DDM leakage level is the aforementioned performance index threshold. For the DDM waveform signal, its performance index can be measured by the DDM leakage level, and for other waveforms, other performance indexes can be used for measurement.

[0044] Optionally, the preset minimum DDM leakage level may be a theoretical value or a preset threshold value, which may be optimized in the process. For example, when it is determined that the DDM leakage level of the current DDM waveform signal is less than the preset minimum DDM leakage level, the minimum DDM leakage level may be modified to the DDM leakage level of the current DDM waveform signal. This allows the current phase calibration to obtain better DDM waveform performance.

[0045] In an exemplary embodiment, the step 10 may also include a pre-screening operation. Specifically, in the process of traversing the preset phase step combination for phase calibration, the phase code table may be pre-screened according to the theoretical gain threshold and the theoretical phase threshold to exclude the phase code whose theoretical gain does not meet the theoretical gain threshold and / or the theoretical phase difference does not meet the theoretical phase threshold. This can shorten the calibration process and avoid meaningless calibration.

[0046] In an exemplary embodiment, in step 20, the third phase code table obtained by taking part or all of the phase codes obtained after phase calibration of the multiple groups of transmitting antennas can be obtained by taking the union of the phase codes obtained after phase calibration of the multiple groups of transmitting antennas as the preferred phase code table, or by taking the union and then deleting some phase codes according to quantity or other requirements. By taking the union, the obtained preferred phase code table can be adapted to different groups of transmitting antennas. The group of transmitting antennas referred to herein refers to all transmitting antennas connected to a chip transmitting module, or can be a group of transmitting antennas used in the chip transmission process.

[0047] In an exemplary embodiment, after obtaining the third phase code table, the method may further include: using empirical values ​​to correct the third phase code table, including but not limited to: removing one or more phase codes from the third phase code table, and / or, adding one or more phase codes to the third phase code table.

[0048] The embodiment of the present disclosure also provides a phase calibration method for performing phase calibration on a waveform signal output by a phase shifter, such as Figure 1B As shown, including:

[0049] Step 10 to step 20: Same as the above steps 10-20, the phase calibration method of the embodiment of FIG. 1 is used to obtain the preferred phase step and the third phase code table used for phase calibration of the phase shifter;

[0050] Step 30, generating a calibration command according to the preferred phase stepping and the third phase code table, and performing phase calibration on one or more antenna boards, wherein the antenna board includes a radar chip and a transmitting antenna connected to the radar chip, and the radar chip includes a phase shifter.

[0051] By adopting the method of this embodiment, the optimal phase step is obtained by combining the waveform performance index, so that the transmission waveform can be closer to the desired waveform and better calibration accuracy can be obtained. In addition, by separately determining the optimal phase step and the phase code table, the calibration time can be shortened.

[0052] The above embodiment method is specifically described below by taking a four-transmit and four-receive millimeter-wave radar chip and a preset waveform being a DDM waveform as an example.

[0053] In this example, if Figure 2As shown, the millimeter wave radar chip includes a transmitting module, a receiving module and a signal processing module, etc. The millimeter wave radar chip may also include other modules, which are not limited in this article. In this example, the transmitting module includes four transmitting channels: the first transmitting channel T1, the second transmitting channel T2, the third transmitting channel T3 and the fourth transmitting channel T4. Each transmitting channel corresponds to a transmitting antenna, totaling 4 transmitting antennas. The transmitting module generates a transmitting waveform according to the configuration, and modulates it to a specified working frequency band (for example, within the 76GHz-81GHz band) to generate a transmitting signal. The transmitting signal is sent to the transmitting antenna for transmission, and the transmitting signal is reflected by the target to generate an echo signal. In this example, the receiving module includes four receiving channels, the first receiving channel R1, the second receiving channel R2, the third receiving channel R3 and the fourth receiving channel R4. Each transmitting channel corresponds to a receiving antenna, totaling 4 receiving antennas. The receiving module processes the echo signal reflected by the target received by the receiving antenna (including but not limited to: amplification, mixing, filtering, down-conversion to baseband signal, etc.) to obtain a baseband echo signal, which is sent to the signal processing module. The signal processing module performs digital signal processing on the received baseband echo signal (including but not limited to: A / D sampling, 1D-FFT (including distance dimension Fourier transform), 2D-FFT (including distance dimension FFT and velocity dimension FFT), CI / NCI (coherent processing / incoherent processing), CFAR (constant false alarm detection), DOA (direction of arrival), etc.), so as to detect the target and estimate the target parameters (including but not limited to: distance, speed, azimuth, pitch angle, signal-to-noise ratio SNR, radar scattering cross section RCS, etc.), and finally sends it to the tracking end for application layer processing.

[0054] The overall processing flow of this embodiment is as follows Figure 3 As shown, the following steps are included:

[0055] Step 1: randomly select one or more antenna boards from the same batch of antenna boards as reference antenna boards, select one reference antenna board for phase calibration, and then determine the preferred phase step of each transmitting antenna;

[0056] An antenna board includes Figure 2 Several antennas and radar chips in the system.

[0057] Step 2: perform phase calibration on the remaining reference antenna plates to generate an optimal phase code table (i.e., the aforementioned third phase code table);

[0058] Step three: perform online phase calibration on other antenna boards in this batch based on the determined preferred phase step and preferred phase code table.

[0059] Since antenna boards of the same batch are manufactured at the same time, the performance difference is relatively small. Therefore, the preferred phase step and preferred phase code table can be determined in batches, that is, the preferred phase step and preferred phase code table obtained after calibration of antenna boards of different batches may be different. In other embodiments, it is not excluded that antenna boards of different batches use the same preferred phase step and preferred phase code table for phase calibration, and this document does not limit this.

[0060] The following is an introduction in steps.

[0061] In the above step 1, the preferred phase step is determined to determine the theoretical phase step used when the antenna board is phase-calibrated. The process is as follows: Figure 4 As shown, any reference antenna board can be selected to determine the preferred phase step, including the following steps:

[0062] Step 1-1, initialize phase parameters, the phase parameters include: minimum DDM leakage parameter leakage_min (for example, set to 0), preferred phase step step_opt = {step0, step1, step2, step3}, phase step combination step_cur, alternative phase code code_opt = {code0, code1, code2, code3, ..., codeN}, phase code table code_table, theoretical gain threshold amp_th, theoretical phase threshold phi_th;

[0063] The minimum DDM leakage parameter leakage_min is a performance indicator for measuring the DDM waveform;

[0064] The preferred phase step step_opt is a step set, which is used to record which antenna corresponds to which phase step is a more preferred solution. The preferred phase step step_opt includes n steps, where n is the number of transmitting antennas included in the antenna board, that is, each transmitting antenna corresponds to a phase step. During initialization, the preferred phase step step_opt is empty;

[0065] The phase step combination step_cur is a set obtained by making n antennas correspond to different phase steps, which is equivalent to a candidate library of the preferred phase step;

[0066] The candidate phase code code_opt is used to record the candidate phase code, one phase code corresponds to one phase;

[0067] The phase code table code_table records one or more phase code tables, for example, can be recorded by a phase code table identifier, each phase code table includes multiple phase codes corresponding to the required multiple phase codes, different code tables may correspond to different phase shifter performances (for example, different gains), and different code tables may have different numbers of phase codes;

[0068] The theoretical gain threshold amp_th and the theoretical phase threshold phi_th are used to exclude the phase codes that do not meet the requirements in the phase code table.

[0069] Step 1-2, pre-screening the phase code table code_table according to the theoretical gain threshold amp_th and the theoretical phase threshold phi_th, and excluding the phase codes whose theoretical gain and theoretical phase difference do not meet the requirements;

[0070] The theoretical gain corresponding to the phase code can be calculated using existing technology. The theoretical gain of each phase code in the phase code table is calculated and then compared with the theoretical gain threshold amp_th respectively, so that the phase code that does not meet the theoretical gain threshold amp_th requirement can be excluded.

[0071] Each phase code corresponds to a theoretical phase. The difference between the theoretical phase and the expected phase corresponding to each phase code is calculated respectively. The obtained multiple differences are compared with the theoretical phase threshold phi_th respectively, and the phase codes that do not meet the requirements of the theoretical phase threshold phi_th are excluded.

[0072] Step 1-3, select one from the phase step combination step_cur as the current transmit phase step, select the phase code table code_table, and generate a phase calibration command according to the current transmit phase step, phase code table, and corner reflector placement parameters;

[0073] Before calibration, in a dark room, a 10dBsm (decibel square meter) angular anti-target is placed at a certain distance R in front of the radar, and the target search range is set in the calibration command.

[0074] When selecting the phase code table code_table, a phase code table with more codes may be selected from multiple phase code tables, or a phase code table with better performance may be selected, that is, the aforementioned first phase code table.

[0075] Step 1-4, transmitting the phase calibration command generated in step 1-3, performing phase calibration on the reference antenna board, and writing the calibrated phase code, i.e., the calibration value, into the flash memory;

[0076] The transmitting module receives the calibration command input from the outside and starts the automatic calibration function of the transmitting phase.

[0077] The calibrated phase code is the phase code corresponding to the current transmission phase step

[0078] The number of phase codes is determined by the phase step value. For example, if the phase step value is 45°, 360 / 45=8 phase codes are required. In order to facilitate data extraction, the number of phase codes can be unified (for example, the maximum number is taken), so that the data in the memory is stored neatly and can be easily accessed.

[0079] Step 1-5, after calibration, power on again, load the phase code, i.e. the calibration value, from the flash and use the current transmission phase to step the transmission signal, calculate the current DDM leakage level leakage_cur and evaluate whether the current DDM leakage level leakage_cur is less than the minimum DDM leakage leakage_min, if yes, execute step 1-6, otherwise execute step 1-7;

[0080] The current DDM leakage level leakage_cur can be calculated by the following method: collect radar echo data containing multiple targets; perform Doppler diversity processing on the collected echo data to divide it into different sub-channels or frequency bands, and each sub-channel corresponds to a specific Doppler frequency shift range; in each sub-channel, extract the target signal and quantify its intensity (which can be done by calculating the energy, power or amplitude of the target signal in each sub-channel); for each sub-channel, calculate the total energy of the target signal contained in it; calculate the leakage level, which can be expressed by the signal leakage ratio (Leakage Ratio) or leakage factor (Leakage Factor), and the leakage level can be defined as the ratio of leakage energy to the total energy of the target signal, or the ratio of leakage energy to the total energy of the background noise.

[0081] Step 1-6, updating (e.g., replacing) the minimum DDM leakage parameter leakage_min with the current DDM leakage level leakage_cur, and writing the current transmit phase step into the preferred phase step step_opt;

[0082] Exemplarily, if the performance indicator threshold is not an extreme value (maximum value or minimum value), the performance indicator threshold may not be updated.

[0083] Step 1-7, determine whether all phase step combinations have been traversed. If so, the preferred phase step obtained in step 1-6 is the final preferred phase step step_opt. The DDM leakage level corresponding to this phase step is the smallest, and the process of determining the preferred phase step is completed. If all phase step combinations have not been traversed, return to step 1-3 and select an untraversed phase step from the phase step combination step_cur as the current transmission phase step.

[0084] In this process, a fixed phase code table is selected, and all phase step combinations are traversed. Phase calibration is first performed to calibrate the phase code corresponding to the current step combination, and then the current step combination and the calibrated phase code are still used to transmit the preset waveform signal (in this case, the DDM waveform signal), and the performance of the preset waveform signal is evaluated, and finally the phase step that can make the transmitted preset waveform signal have the best performance is selected as the preferred phase step. By combining the waveform performance index to obtain the preferred phase step, the transmitted waveform can be made closer to the expected waveform and obtain better calibration accuracy.

[0085] In the above step 2, the process of determining the preferred phase code table is as follows: Figure 5 As shown, the following steps are included:

[0086] Step 2-1, taking the preferred phase step step_opt obtained in the above step 1 as the current transmit phase step, selecting the phase code table code_table, and generating a phase calibration command according to the current transmit phase step, the phase code table, and the corner reflector placement position and other parameters;

[0087] When selecting a phase code table, it can be selected according to the preferred phase step, for example, a phase code table whose phase is close to the preferred phase step is selected as the phase code table used in this step (i.e., the aforementioned second phase code table). The phase code tables used when calibrating different reference antenna boards can be the same or different.

[0088] Step 2-2, sending the phase calibration command generated in step 2-1, performing phase calibration on each reference antenna board, recording the calibrated phase code as the candidate phase code code_opt, and writing it into the flash;

[0089] This process can be performed on the remaining reference antenna boards except the reference antenna board used in performing step 1, so as to obtain a universal phase code table after synthesis.

[0090] For example, for transmitting antennas Tx1, Tx2, Tx3 and Tx4, the preferred phase steps are 270°, 0°, 180°, and 45°, respectively. Taking TX3 as an example, its preferred phase step is 180°, so the phase code that needs to be used by this antenna includes a 0-degree phase code and a 180-degree phase code. Then the phase sequence of Tx3 is 0°, 180°, 0°(360°), 180°(540°)…. To achieve this step, it is necessary to find a phase code that can actually adjust Tx3 to 180° or a phase code close to 180° from the phase code table containing theoretical phase modulation 178, 179, 180, 181, and 182. This phase code is the alternative phase code.

[0091] The candidate phase code may be part or all of the phase codes in the phase code table. There are 6 phase codes in the phase code table, but only 4 are actually used during calibration, so these 4 phase codes are candidate phase codes.

[0092] Step 2-3, determine whether all reference antenna boards have been traversed, if yes, execute step 2-4, otherwise, replace with other uncalibrated reference antenna boards and return to step 2-1;

[0093] Step 2-4, synthesizing the candidate phase codes of all reference antenna boards to obtain the preferred phase code table code_table_opt.

[0094] If the reference antenna board used in executing steps 1-1 to 1-7 is not calibrated in this process, the phase code obtained when the preferred phase step is calibrated in the above steps 1-1 to 1-7 is used as the candidate phase code of the reference antenna board. The preferred phase code table is obtained by integrating the candidate phase codes of all reference antenna boards, and the union of the candidate phase codes can be taken as the preferred phase code table. Optionally, after obtaining the preferred phase code table, some phase codes can be deleted (for example, when there is a requirement for the number of phase codes in the phase code table), or some phase codes can be added based on experience.

[0095] In this embodiment, in step 1, the phase code table is first fixed, and the preferred phase step is found by phase calibration of a reference antenna board. Then, in step 2, the preferred phase step determined in step 1 is used to perform phase calibration on multiple reference antenna boards, and a universal preferred phase code table is finally obtained by collecting the alternative phase codes of different reference antenna boards. In this embodiment, the preferred phase step and the preferred phase code table are determined in two steps, which can greatly reduce the calibration time, shorten the calibration process, and save resources compared to traversing the phase step and the phase code table in one process.

[0096] In the above step 3, the process of performing online phase calibration on other antenna boards in this batch based on the determined preferred phase step and preferred phase code table is as follows: Figure 6 As shown, the following steps are included:

[0097] Step 3-1, generating a phase calibration command according to the preferred phase step and the preferred phase code table;

[0098] Step 3-2, sending a phase calibration command to perform online phase calibration on the antenna boards other than the reference antenna board.

[0099] The preferred phase step is considered to be the expected theoretical phase step. Ultimately, other uncalibrated antenna boards need to be calibrated to select the phase code of each transmission channel that is closest to the preferred phase step in the preferred phase code table.

[0100] The disclosed embodiment is simple, fast and flexible to use, and is suitable for both general scenarios and rapid calibration during mass production. For an antenna board, in a dark room, a command is directly sent to a corner reflector target or a simulator target, and any phase calibration can be automatically completed in 2 seconds. The calibrated value is stored in the flash and can also be echoed through the serial port.

[0101] According to the phase stepping and phase code table, the phase calibration command is adjusted to perform the online phase calibration on the antenna board (corresponding to the above steps 1-4 and 3-2). Figure 7 As shown, the following steps are included:

[0102] Step 4-1, transmitting a single-frame single-phase point calibration waveform;

[0103] The transmitting module configures the phase of the transmitting channel to the phase of the specified position in the table according to the predetermined phase code table, and then sends the 4T4R calibration waveform (such as TDM-MIMO waveform - waveform used during calibration) at the phase point. The transmitting waveform is as follows Figure 8 As shown:

[0104] The phase code table predetermined for step 1-4 is the phase code table selected in step 1-3, and the phase code table predetermined for step 3-2 is the preferred phase code table obtained in step 2.

[0105] Step 4-2, performing echo preprocessing;

[0106] Echo preprocessing includes but is not limited to: the signal processing module samples the received echo signal (ADC), 2D-FFT processing (including distance dimension FFT and velocity dimension FFT), that is, transforming the time domain signal into the frequency domain, NCI (non-coherent processing), etc.

[0107] Step 4-3, extracting the single-phase point target amplitude and phase;

[0108] Process the 2D-FFT result in step 4-2: search for the target within the target search range, and save the amplitude and phase of the target in each receiving channel.

[0109] Repeat the above steps 4-1 to 4-3 until the predetermined phase code table is traversed.

[0110] Step 4-4, single phase point processing;

[0111] Single phase point processing is used for phase analysis.

[0112] Step 4-5, perform multi-frame optimization processing;

[0113] After the phase code table is traversed, multiple frames of results (including the target amplitude and phase) are obtained; the core of multi-frame optimization processing is to find the appropriate phase among many results. The detailed processing steps include:

[0114] 1) 0 bias processing

[0115] Perform zero bias processing on each receiving channel: for example, taking the theoretical 45-degree phase setting value as the benchmark, subtract the test value of the 45-degree phase point from each phase point and add 45 degrees.

[0116] 2) Phase winding removal

[0117] The phase of each phase point of each receiving channel is unwrapped. Phase unwrapping is a signal processing technology used to process signals with sudden phase changes or phase jumps. When the phase of a signal suddenly changes, a phase jump usually occurs, that is, the phase suddenly jumps from one value to another. In order to solve the problem caused by the phase jump, the phase unwrapping process limits the phase difference within a suitable range and makes appropriate corrections to restore the continuous phase information of the signal.

[0118] 3) Channel average

[0119] At each phase point, the phase and amplitude of the phase values ​​of each receiving channel are averaged.

[0120] 4) Choose the right phase

[0121] Among the averaged phase points, a suitable phase is selected, and the selection criterion is: the error with the ideal phase is minimal.

[0122] Step 4-6: Calibration result storage and display.

[0123] The selected results are stored in flash and displayed through the serial port.

[0124] This example method has the following advantages:

[0125] 1. This example combines the actual working waveform and the influence of DDM leakage during the calibration process, and improves the calibration accuracy by introducing a feedback mechanism, which can effectively reduce the leakage and inter-channel coupling caused by inaccurate transmission phase;

[0126] 2. Strong scalability. By pre-screening the phase code and integrating the calibration results of multiple reference boards, the number of phase code tables is effectively reduced, and a balance is achieved between calibration time and calibration performance, which is suitable for mass production and general use scenarios;

[0127] 3. Simple operation. By sending a calibration command to the radar, a single antenna board and any phase step can be quickly calibrated.

[0128] In an exemplary embodiment of the present disclosure, a calibration device (such as a host computer) is also provided. The calibration device may include a processor, a memory, and a computer program stored in the memory and executable on the processor, and the processor implements the calibration method of the present disclosure when executing the computer program.

[0129] like Fig. 9 As shown, in one example, the calibration device 100 may include: a processor 110, a memory 120, a bus system 130 and a transceiver 140, wherein the processor 110, the memory 120 and the transceiver 140 are connected via the bus system 130, the memory 120 is used to store instructions, and the processor 110 is used to execute the instructions stored in the memory 120 to control the transceiver 140 to send signals. Specifically, the operations of steps 1 to 3 in the above method can be controlled and executed by the processor 110, and the phase calibration command generated by the processor 110 can be sent to the phase shifter via the transceiver 140, and the phase shifter performs Figure 7 The phase calibration process is shown.

[0130] It should be understood that the processor 110 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0131] The memory 120 may include a read-only memory and a random access memory, and provide instructions and data to the processor 110. A portion of the memory 120 may also include a non-volatile random access memory. For example, the memory 120 may also store information on the device type or information related to the phase code as described above.

[0132] In addition to the data bus, the bus system 130 may also include a power bus, a control bus, and a status signal bus. Fig. 9 Various buses are labeled as bus system 130 .

[0133] In the implementation process, the processing performed by the calibration device can be completed by the hardware integrated logic circuit in the processor 110 or the instructions in the form of software. That is, the steps of the method disclosed in the embodiment of the present disclosure can be embodied as being executed by a hardware processor, or being executed by a combination of hardware and software modules in the processor. The software module can be located in a storage medium such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 120, and the processor 110 reads the information in the memory 120 and completes the steps of the above method in combination with its hardware. To avoid repetition, it will not be described in detail here.

[0134] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

Claims

1. A phase calibration method, characterized in that: The phase step and phase code table used to obtain the phase shifter phase calibration include: A first phase code table is preset, wherein the first phase code table includes a plurality of phase codes, the first phase code table is used to traverse a preset phase step combination for phase calibration, a preset waveform signal is transmitted using the calibrated phase code, and whether a performance index of the preset waveform signal meets a performance index threshold is determined, and a phase step combination whose performance index meets the performance index threshold is used as a preferred phase step; The preferred phase stepping and one or more second phase code tables are used to perform phase calibration on multiple groups of transmitting antennas, and a third phase code table is obtained by taking part or all of the phase codes obtained after the phase calibration of the multiple groups of transmitting antennas.

2. The phase calibration method according to claim 1, characterized in that: The taking the phase step combination whose performance index meets the performance index threshold as the preferred phase step includes: taking the phase step combination with the best performance index as the preferred phase step.

3. The phase calibration method according to claim 2, characterized in that: The method further comprises: When the performance indicator of the preset waveform signal is better than the performance indicator threshold, the performance indicator threshold is updated using the performance indicator of the preset waveform signal.

4. The phase calibration method according to claim 1, characterized in that: The step of transmitting a preset waveform signal by using the calibrated phase code and determining whether a performance index of the preset waveform signal meets a performance index threshold comprises: The DDM waveform signal is transmitted using the calibrated phase code, and it is determined whether the DDM leakage level of the DDM waveform signal is less than a preset minimum DDM leakage level.

5. The phase calibration method according to claim 4, characterized in that: The method further comprises: When the DDM leakage level of the DDM waveform signal is less than a preset minimum DDM leakage level, the minimum DDM leakage level is replaced with the current DDM leakage level of the DDM waveform signal.

6. The phase calibration method according to claim 1, characterized in that: After obtaining the third phase code table, the method further includes: One or more phase codes are removed from the third phase code table, and / or one or more phase codes are added to the third phase code table.

7. The phase calibration method according to claim 1, characterized in that: The adopting the first phase code table to traverse the preset phase step combination to perform phase calibration includes: generating a preset phase step combination based on the number of transmit antennas and the desired phase; When the first phase code table is used to traverse the preset phase step combination for phase calibration, a preset phase step combination is selected from the preset phase step combination, and a phase calibration command is generated according to the selected preset phase step combination, the first phase code table and the target position to perform phase calibration, and a calibrated phase code is obtained until all preset phase step combinations are traversed.

8. The phase calibration method according to claim 7, characterized in that: When performing phase calibration, phase calibration is performed on a group of transmitting antennas located on the same chip.

9. The phase calibration method according to claim 1, characterized in that: In the process of traversing the preset phase step combination for phase calibration, the phase code table is pre-screened according to the theoretical gain threshold and the theoretical phase threshold to exclude phase codes whose theoretical gain does not meet the theoretical gain threshold and / or whose theoretical phase difference does not meet the theoretical phase threshold.

10. A phase calibration method, characterized in that: Used to perform phase calibration on the phase shifter output waveform signal, including: Adopting the phase calibration method described in any one of claims 1 to 9 to obtain the optimal phase step and the third phase code table; A calibration command is generated according to the preferred phase stepping and the third phase code table to perform phase calibration on one or more antenna boards, wherein the antenna board includes a radar chip and a transmitting antenna connected to the radar chip.

11. A calibration device comprising a processor and a memory storing a computer program executable on the processor, wherein: When the processor executes the program, the steps of the phase calibration method according to any one of claims 1 to 9 or claim 10 are implemented.

12. A non-transitory computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute the method of any one of claims 1 to 9 or claim 10.

Images