Nonlinear second harmonic distortion correction method, device, equipment and storage medium

Abstract

The application discloses a kind of nonlinear second harmonic distortion correction method, device, equipment and storage medium, the method includes: after receiving calibration trigger signal, test signal of preset frequency is generated in response to calibration trigger signal;Based on the statistical distribution characteristics of test signal, determine the compensation parameter for inhibiting second harmonic distortion;Receive radio frequency service signal, and based on compensation parameter, radio frequency service signal is carried out nonlinear compensation, and the compensated radio frequency service signal is obtained and output.Because the application generates test signal in response to calibration trigger signal, then based on the statistical distribution characteristics of test signal, determine the compensation parameter for inhibiting second harmonic distortion, finally based on compensation parameter, radio frequency service signal is carried out nonlinear compensation, compared with prior art, the application effectively reduces the calculation complexity, and improves real-time.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a nonlinear second harmonic distortion correction method, apparatus, device, and storage medium. Background Technology

[0002] In modern wireless communication systems, especially high-frequency broadband systems such as 5G NR, millimeter-wave communication, and satellite communication, the front-end of the radio frequency receiver includes nonlinear devices such as low-noise amplifiers (LNAs), mixers, and analog-to-digital converters (ADCs). These devices introduce nonlinear distortion during signal processing, with second harmonic distortion (HD2) being a particularly prominent problem. The frequency of the second harmonic component is twice that of the input signal carrier frequency. In broadband systems (such as OFDM), it is very likely to fall into the target signal band or its adjacent channels, causing spectrum pollution, deterioration of adjacent channel leakage ratio (ACLR), and a significant reduction in the receiver's signal-to-noise ratio (SNR) and sensitivity, thereby affecting the overall bit error rate performance of the system.

[0003] To suppress second-harmonic distortion, various technical solutions have been proposed. Digital predistortion (DPD) technology cancels distortion by injecting inverse nonlinearity at the front end of the signal chain. However, this method requires accurate modeling of the system's nonlinear characteristics, typically involving complex operations such as high-order polynomial inversion, resulting in a heavy computational burden and making it difficult to deploy in resource-constrained RF chips or real-time processing scenarios requiring low latency. Adaptive filtering techniques (such as LMS and RLS algorithms) suppress distortion by dynamically adjusting filter coefficients through error feedback, but their convergence speed and stability face challenges under conditions of rapid channel changes or wideband signals, making real-time performance difficult to guarantee.

[0004] Therefore, there is an urgent need for a nonlinear second harmonic distortion correction method that can effectively reduce computational complexity and improve real-time performance. Summary of the Invention

[0005] The main objective of this invention is to provide a nonlinear second harmonic distortion correction method, apparatus, device, and storage medium, aiming to solve the technical problems of high computational complexity and poor real-time performance of existing second harmonic distortion correction technologies.

[0006] To achieve the above objectives, the present invention provides a nonlinear second harmonic distortion correction method, the method comprising the following steps:

[0007] Upon receiving a calibration trigger signal, a test signal of a preset frequency is generated in response to the calibration trigger signal.

[0008] Based on the statistical distribution characteristics of the test signal, compensation parameters for suppressing second harmonic distortion are determined.

[0009] The system receives radio frequency (RF) service signals and performs nonlinear compensation on the RF service signals based on the compensation parameters to obtain and output the compensated RF service signals.

[0010] Optionally, the step of determining the compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal includes:

[0011] Collect and cache a preset number of data points of the test signal;

[0012] Based on the preset number of data points, the skewness value of the output signal after the nonlinear transformation of the test signal is determined, and the skewness value is used as the statistical distribution characteristic of the test signal. The nonlinear transformation includes compensation parameters to be determined.

[0013] The compensation parameters are iteratively updated with the goal of minimizing the absolute value of the skewness.

[0014] When the absolute value of the skewness value satisfies the preset convergence condition during the iterative update process, the current compensation parameter is used as the compensation parameter to suppress second harmonic distortion.

[0015] Optionally, the step of determining the skewness value of the output signal after nonlinear transformation of the test signal based on the preset number of data points, and using the skewness value as the statistical distribution characteristic of the test signal, includes:

[0016] Based on the preset number of data points, the mean and standard deviation of the output signal after the nonlinear transformation of the test signal are determined;

[0017] Based on the mean and the preset number of data points, the third central moment of the output signal is determined;

[0018] The skewness value is determined based on the third central moment and the standard deviation, and the skewness value is used as the statistical distribution characteristic of the test signal.

[0019] Optionally, the step of iteratively updating the compensation parameters with the optimization objective of minimizing the absolute value of the skewness includes:

[0020] A cost function is constructed based on the absolute value of the skewness value, and the gradient of the cost function with respect to the compensation parameter is determined.

[0021] Based on the gradient, the compensation parameters are updated using gradient descent until the absolute value of the skewness value satisfies the preset convergence condition.

[0022] Optionally, the step of generating a test signal of a preset frequency in response to the calibration trigger signal after receiving the calibration trigger signal includes:

[0023] In response to the calibration trigger signal, a test signal acquisition request signal is generated;

[0024] Based on the test signal, a request signal is obtained, and the auxiliary phase-locked loop is controlled to generate a single-frequency signal of a preset frequency, and the single-frequency signal is used as the test signal.

[0025] Optionally, the step of receiving the radio frequency service signal, performing nonlinear compensation on the radio frequency service signal based on the compensation parameters, and obtaining and outputting the compensated radio frequency service signal includes:

[0026] Receive radio frequency service signals and determine the in-phase branch signals and quadrature branch signals in the radio frequency service signals;

[0027] Based on the compensation parameters, nonlinear compensation is performed on the in-phase branch signal and the quadrature branch signal respectively to obtain the compensated in-phase branch signal and the compensated quadrature branch signal.

[0028] The compensated in-phase branch signal and the compensated quadrature branch signal are used as the compensated radio frequency service signal.

[0029] Optionally, before the step of performing nonlinear compensation on the radio frequency service signal based on the compensation parameters, the method further includes:

[0030] Determine whether the compensation enable signal is valid;

[0031] If the compensation enable signal is valid, then the step of performing nonlinear compensation on the radio frequency service signal based on the compensation parameters is executed;

[0032] If the compensation enable signal is invalid, the step of performing nonlinear compensation on the radio frequency service signal based on the compensation parameters is bypassed, and the radio frequency service signal is output.

[0033] Furthermore, to achieve the above objectives, the present invention also proposes a nonlinear second harmonic distortion correction device, the device comprising:

[0034] The signal generation module is used to generate a test signal of a preset frequency in response to the calibration trigger signal after receiving the calibration trigger signal.

[0035] The parameter determination module is used to determine the compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal.

[0036] The signal processing module is used to receive radio frequency service signals, perform nonlinear compensation on the radio frequency service signals based on the compensation parameters, and obtain and output the compensated radio frequency service signals.

[0037] Furthermore, to achieve the above objectives, the present invention also proposes a nonlinear second harmonic distortion correction device, the device comprising: a memory, a processor, and a nonlinear second harmonic distortion correction program stored in the memory and executable on the processor, the nonlinear second harmonic distortion correction program being configured to implement the steps of the nonlinear second harmonic distortion correction method as described above.

[0038] Furthermore, to achieve the above objectives, the present invention also proposes a storage medium storing a nonlinear second harmonic distortion correction program, wherein the nonlinear second harmonic distortion correction program, when executed by a processor, implements the steps of the nonlinear second harmonic distortion correction method as described above.

[0039] This invention discloses a method for generating a test signal of a preset frequency in response to a calibration trigger signal; determining compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal; receiving an RF service signal and performing nonlinear compensation on the RF service signal based on the compensation parameters to obtain and output the compensated RF service signal. Because this invention generates a test signal in response to a calibration trigger signal, then determines the compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal, and finally performs nonlinear compensation on the RF service signal based on the compensation parameters, compared with existing technologies, this invention effectively reduces computational complexity and improves real-time performance. Attached Figure Description

[0040] Figure 1 This is a flowchart illustrating the first embodiment of the nonlinear second harmonic distortion correction method of the present invention;

[0041] Figure 2 This is a schematic diagram of a typical communication receiver module;

[0042] Figure 3 This is a flowchart illustrating the second embodiment of the nonlinear second harmonic distortion correction method of the present invention;

[0043] Figure 4 This is a schematic diagram of the architecture for second harmonic distortion calibration of the present invention;

[0044] Figure 5 This is a block diagram illustrating the implementation of the second harmonic calibration of the present invention;

[0045] Figure 6 This is a flowchart illustrating the third embodiment of the nonlinear second harmonic distortion correction method of the present invention;

[0046] Figure 7 This is a structural block diagram of the first embodiment of the nonlinear second harmonic distortion correction device of the present invention;

[0047] Figure 8This is a schematic diagram of the structure of a nonlinear second harmonic distortion correction device for the hardware operating environment involved in the embodiments of the present invention.

[0048] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0049] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0050] This invention provides a nonlinear second harmonic distortion correction method, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the nonlinear second harmonic distortion correction method of the present invention.

[0051] In this embodiment, the nonlinear second harmonic distortion correction method includes steps S10~S30:

[0052] Step S10: After receiving the calibration trigger signal, generate a test signal of a preset frequency in response to the calibration trigger signal.

[0053] It should be noted that the executing entity in this embodiment can be a computer server device with data processing, network communication, and program execution functions applied in a second harmonic distortion correction scenario, such as a communication receiving device, radio frequency receiver, or zero / low intermediate frequency receiver, or an electronic device capable of realizing the above functions (such as a nonlinear second harmonic distortion correction device). The following uses a system including a nonlinear second harmonic distortion correction device (hereinafter referred to as the system) as an example to illustrate this embodiment and the following embodiments.

[0054] It should be understood that the calibration trigger signal can be a control signal or command used to initiate the entire second harmonic distortion calibration process. The calibration trigger signal can come from two sources: automatic triggering upon power-on and external manual triggering.

[0055] Understandably, a test signal can refer to a signal with known characteristics generated specifically for measuring the nonlinear characteristics of a system. It is not the communication service data to be received, but rather a tool signal used for diagnosing and calibrating the system.

[0056] It should be noted that a preset frequency test signal refers to a test signal whose frequency value can be pre-configured via software or hardware. This provides flexibility, allowing equipment manufacturers or users to set the most suitable test frequency according to different application scenarios and different operating frequency bands, making calibration more targeted and universal.

[0057] In a specific implementation, a test signal acquisition request signal can be generated in response to the calibration trigger signal; based on the test signal acquisition request signal, the auxiliary phase-locked loop can be controlled to generate a single-frequency signal of a preset frequency, and the single-frequency signal can be used as a test signal.

[0058] It should be understood that the test signal acquisition request signal can be a control signal used to notify and initiate the downstream test signal generation module.

[0059] It's important to clarify that the auxiliary phase-locked loop (PLL) is used in contrast to the main PLL in the receiver's main signal path. The main PLL generates the receiver's local oscillator (LO) signal, responsible for down-converting the received RF service signal to baseband or intermediate frequency (IF), and its frequency varies with the service channel. The auxiliary PLL, on the other hand, is an independent, dedicated frequency synthesizer. Its activation, deactivation, and frequency setting are independent of the main service path; therefore, the generation of test signals will not interfere with or be constrained by the RF service signal being processed.

[0060] It should be understood that a single-frequency signal, or single-tone signal, refers to a signal that contains only a single frequency component in the frequency domain, ideally a pure sine wave or cosine wave.

[0061] It should be noted that the second harmonic generated by a single-frequency signal passing through a nonlinear device has a definite and unique position in the frequency spectrum, making it easy to observe and measure. Furthermore, generating a high-quality single-frequency signal, whether through an auxiliary phase-locked loop or other methods, is technically relatively simple and cost-effective.

[0062] Step S20: Based on the statistical distribution characteristics of the test signal, determine the compensation parameters used to suppress second harmonic distortion.

[0063] It should be explained that statistical distribution characteristics can refer to mathematical indices that quantify the symmetry of the probability distribution shape of a signal amplitude, i.e., the skewness of the signal.

[0064] It should be understood that second harmonic distortion refers to the generation of a new frequency component in the output signal at twice the frequency of the input signal due to the nonlinearity of the devices in the radio frequency receiving link. This is a harmful signal distortion.

[0065] It should be noted that the skewness value of the output signal after the nonlinear transformation of the test signal can be determined, and the skewness value is used as the statistical distribution characteristic of the test signal. The nonlinear transformation includes compensation parameters to be determined. The compensation parameters are iteratively updated with the goal of minimizing the absolute value of the skewness value. When the absolute value of the skewness value meets the preset convergence condition during the iterative update process, the current compensation parameter is used as the compensation parameter for suppressing second harmonic distortion.

[0066] Since this embodiment mainly focuses on the suppression of second harmonic distortion, the analysis process ignores third-order and higher-order distortion.

[0067] Since the I / Q channels are symmetrical real signals, only one channel needs to be analyzed. For example, refer to... Figure 2 , Figure 2 This is a typical schematic diagram of a communication receiver module. The signal input includes the Ref signal test signal required by the HD2 algorithm and the normal simulated RF service signal chirp / QPSK. The analog front-end (AFE) at the signal receiver includes a mixer that down-converts the receiver's LO, a filter, and a digital-to-analog converter (ADC). After ADC conversion, the signal enters the HD2 module corresponding to the HD2 algorithm. When the strobe signal sel=00, the test signal enters the HD2_CALC module (calculation submodule) to calculate the compensation coefficient. Subsequently, when sel=01, the compensation coefficient is sent to the HD2_INV module (compensation submodule) to perform second harmonic distortion compensation on the input RF service signal (Chirp / QPSK sig_in). After the algorithm processing is completed, the compensated RF service signal (Chirp / QPSK sig_out) is output.

[0068] It should be noted that the HD2 algorithm can refer to the complete method flow of this invention, and the HD2 module can refer to the hardware circuit, logic unit or system sub-architecture that implements the above-mentioned HD2 algorithm function in the digital part of the receiver (after ADC). It is the physical or logical carrier of the HD2 algorithm.

[0069] Mathematical derivation of the HD2 algorithm: For nonlinear systems, a polynomial model can be used for approximation. Assume the input signal (i.e., the test signal) is a single-frequency sinusoidal signal. Nonlinear device output signal The relationship is:

[0070] ;

[0071] The above equation ignores nonlinear terms of order three and above, where The linear gain coefficient, The coefficients of the quadratic nonlinear term are expanded to obtain:

[0072] ;

[0073] It is evident that the existence of the quadratic term causes the output signal to contain both a DC component and a second harmonic component. Now that we understand the cause of the second harmonic, we will analyze the statistical characteristics (i.e., statistical distribution characteristics) of the nonlinear signal:

[0074] First, we introduce the concept of skewness, which describes the asymmetry of a signal distribution relative to its mean. A skewness value of 0 indicates a symmetrical distribution, while a non-zero value indicates a skewed distribution.

[0075] ;

[0076] In the formula, The skewness value of the output signal is represented by y, and the output signal after the test signal undergoes nonlinear transformation. It is the mean of the output signal. It is the standard deviation of the output signal.

[0077] In a practical implementation, the mean value of the output signal after the test signal undergoes a nonlinear transformation can be determined. and standard deviation Then, the third central moment of the output signal is determined based on the mean. Then, the skewness value is determined based on the third-order central moment and the standard deviation. The skewness value is used as the statistical distribution characteristic of the test signal.

[0078] The following analysis examines the effects of the fundamental signal and nonlinear terms on the skewness:

[0079] The statistical properties of the quadratic term are used to analyze the impact of quadratic nonlinearity on radio frequency service signals, given the input signal. It is a uniformly distributed signal with zero mean, and the signal amplitude is in and Between these two points, the probability density function is:

[0080] .

[0081] Just care The effect on the distribution is temporarily ignored, so the squaring operation performs a nonlinear transformation on the signal distribution and calculates... Mean:

[0082] .

[0083] Solving for:

[0084] .

[0085] The squared signal has a positive mean. Since squaring maps all negative values ​​to positive ones, the signal probability density function is concentrated on the positive half-axis, losing the symmetry of the original distribution. Therefore, for uniformly distributed signals... The introduction of the quadratic term disrupts the symmetry, directly leading to skewed statistical distributions with non-zero values.

[0086] Statistical properties of cubic terms, assuming For a zero-mean signal, at this time:

[0087] .

[0088] because It is an odd function and Because of the symmetry, the positive and negative integrals cancel each other out. Therefore, the cubic term does not directly affect the mean of the signal, and further nonlinear transformations of the cubic term will not destroy the symmetry of the input signal or change the skewness of the distribution.

[0089] Based on the above definitions, it can be seen that the skewness and quadratic nonlinear coefficients... The following relationships exist:

[0090] ;

[0091] skewness value varies Increases and deviates significantly from 0, when When the skewness is 0, the signal is recovered, which is the basis for constructing the cost function.

[0092] Nonlinear compensation models, performed in the digital domain, require the construction of an inverse nonlinear model, typically employing the same polynomial form to compensate for its own nonlinear effects.

[0093] ;

[0094] in, It is a compensation coefficient, the purpose of which is to make the second harmonic component approach zero.

[0095] The above derivation shows that second harmonics cause the signal distribution to deviate from symmetry, which can be addressed by minimizing the absolute value of the skewness. Convergence compensation coefficient To indirectly eliminate second harmonics by restoring the signal distribution to symmetry, the solution of standard deviation is changed to absolute value averaging due to the complexity of optimizing skewness in actual implementation. It is difficult to evaluate whether the skewness is a convex function. Therefore, the mean condition is added when calculating the gradient to improve convergence.

[0096] Gradient descent can be used to effectively update the compensation coefficients.

[0097] ;

[0098] Wherein, cost function It can be done through weighting factors. Control the priority of skewness and mean convergence respectively.

[0099] It should be noted that gradient calculation can be approximated using numerical methods:

[0100] ;

[0101] In the formula, To solve for the small perturbation caused by the gradient increase, the optimal compensation coefficient is found through multiple iterations. At this point, the second harmonic component of the compensated signal approaches zero.

[0102] In a specific implementation, the step of iteratively updating the compensation parameters with the optimization objective of minimizing the absolute value of the skewness includes: constructing a cost function based on the absolute value of the skewness and determining the gradient of the cost function with respect to the compensation parameters; updating the compensation parameters using gradient descent based on the gradient until the absolute value of the skewness satisfies a preset convergence condition.

[0103] Step S30: Receive the radio frequency service signal, and perform nonlinear compensation on the radio frequency service signal based on the compensation parameters to obtain and output the compensated radio frequency service signal.

[0104] It should be understood that radio frequency service signals can refer to broadband signals received by a communication receiver that carry actual communication services (such as voice and data).

[0105] This embodiment discloses a method for generating a test signal of a preset frequency in response to a calibration trigger signal; determining compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal; receiving an RF service signal and performing nonlinear compensation on the RF service signal based on the compensation parameters to obtain and output the compensated RF service signal. Because this embodiment generates a test signal in response to a calibration trigger signal, then determines the compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal, and finally performs nonlinear compensation on the RF service signal based on the compensation parameters, compared to existing technologies, this embodiment effectively reduces computational complexity and improves real-time performance.

[0106] refer to Figure 3 , Figure 3 This is a flowchart illustrating the second embodiment of the nonlinear second harmonic distortion correction method of the present invention.

[0107] Based on the first embodiment described above, in this embodiment, step S20 includes steps S201 to S204:

[0108] Step S201: Collect and cache a preset number of data points of the test signal.

[0109] Step S202: Based on the preset number of data points, determine the skewness value of the output signal after the nonlinear transformation of the test signal, and use the skewness value as the statistical distribution characteristic of the test signal. The nonlinear transformation includes compensation parameters to be determined.

[0110] Step S203: Iteratively update the compensation parameters with the goal of minimizing the absolute value of the skewness.

[0111] Step S204: When the absolute value of the skewness value satisfies the preset convergence condition during the iterative update process, the current compensation parameter is used as the compensation parameter for suppressing second harmonic distortion.

[0112] It should be understood that since skewness is the ratio of the third central moment to the cube of the standard deviation, calculating the mean, standard deviation, and third central moment requires summing and averaging a series of data. Without a sufficient number of samples, these statistical values ​​are meaningless or prone to significant errors due to noise and transient fluctuations. Therefore, it is necessary to collect and cache a predetermined number of data points of the test signal to smooth out noise, so that the calculated skewness value better reflects the statistical characteristics of the signal's nonlinear distortion itself, rather than accidental noise interference, thereby improving the robustness of the algorithm's convergence.

[0113] In a specific implementation, the step of determining the skewness value of the output signal after nonlinear transformation of the test signal based on the preset number of data points, and using the skewness value as the statistical distribution characteristic of the test signal, may include: determining the mean and standard deviation of the output signal after nonlinear transformation of the test signal based on the preset number of data points; determining the third central moment of the output signal based on the mean and the preset number of data points; determining the skewness value based on the third central moment and the standard deviation, and using the skewness value as the statistical distribution characteristic of the test signal.

[0114] For example, refer to Figure 4 , Figure 4 This is a schematic diagram of the architecture for second harmonic distortion calibration. A zero / low IF receiver is used as an example. The algorithm of this invention is applied to the receiver's digital-to-analog converter and processed in the digital domain. This zero / low IF receiver easily detects high-order harmonic distortions other than the fundamental signal at the digital end, with second harmonic distortion (HD2) being particularly severe. This is mainly due to the presence of nonlinear devices in the system (such as power amplifiers and mixers). The invention, located in the green box, calculates and compensates for both the I and Q channels separately to ultimately eliminate second harmonic distortion.

[0115] In this embodiment, the RF service signal is coupled into the receiver via an antenna and a Balun for I and Q channel reception. The Ref signal test signal required by the HD2 algorithm is generated by a phase-locked loop as an AUX LO single-tone signal, which is an auxiliary LO relative to the main receiver LO. The RF service signal or test signal passes through a series of analog devices to reach the HD2 module, which is the main module of this invention, for algorithm processing. The two muxers simultaneously select 0 or 1, indicating whether to follow the i-branch or q-branch. After being processed by the HD2 module, the RF service signal will continue to undergo the subsequent digital front-end RXDFE operation of the zero / low intermediate frequency receiver.

[0116] In practical implementation, since radio frequency (RF) service signals are typically separated into I and Q baseband signals for processing in the digital domain, the step of receiving the RF service signal, performing nonlinear compensation on the RF service signal based on the compensation parameters, and obtaining and outputting the compensated RF service signal includes: receiving the RF service signal; determining the in-phase branch signal (I-channel signal) and the quadrature branch signal (Q-channel signal) in the RF service signal; performing nonlinear compensation on the in-phase branch signal and the quadrature branch signal respectively based on the compensation parameters to obtain the compensated in-phase branch signal and the compensated quadrature branch signal; and using the compensated in-phase branch signal and the compensated quadrature branch signal as the compensated RF service signal.

[0117] Test signals and RF service signals are injected as excitation through the control module (HD2_CAL_CTRL module), and other register configurations are also injected simultaneously. For example... Figure 5 As shown, Figure 5 This is a block diagram illustrating the implementation of the second harmonic calibration method of this invention. The light green control module can determine IQ multiplexing and the acquisition of offline test signals through register configuration. Test signal data is sent to the parameter calculation submodule (HD2_CAL module), which mainly calculates compensation parameters and ultimately outputs the compensation parameter C2_hat to the compensation execution module (including the I-channel signal compensation execution module and the Q-channel signal compensation execution module) to perform independent online compensation for the I and Q channels of the RF line service signal. The I-channel signal compensation execution module compensates the I-channel signal of the RF line service signal, and the Q-channel signal compensation execution module compensates the Q-channel signal of the RF line service signal.

[0118] like Figure 5As shown, after power-on startup, the parameter calculation submodule can be triggered by power-on or manually, both on the rising edge. A single trigger automatically calculates and iterates the second harmonic distortion of the I and Q channels to obtain the calibration parameters for both channels. Step 1: Upon detecting the rising edge of the calibration trigger signal, the control module immediately sends a test signal acquisition request signal, that is, pulls the test signal acquisition flag hd2_auto_testdata_flag high. Step 2: When hd2_auto_testdata_flag is high, the test signal generation module TEST_SIGNAL_GEN, corresponding to the auxiliary phase-locked loop AUX LO, generates a single-tone test signal. The frequency is controlled by a preset register. The test signal is input to the control module through the input port, and simultaneously provides a data count value hd2_delay_cnt. Step 3: When hd2_delay_cnt reaches the pre-configured data count register value, it is considered that the offline test data has arrived, and the compensation parameter calculation can begin. In this embodiment, the number of data points is preset to 1024 points, which can be determined by algorithm modeling and is an integer multiple of the frequency period oversampling factor; Step 4: After the test data arrives at the control module, the 1024 data points preset in the register are automatically obtained and the parameter calculation submodule is used to calculate the inverse coefficient of second harmonic distortion: by default, the I-channel parameter calculation starts first and then the Q-channel parameter calculation starts automatically; Step 5: When both I and Q channels are completed, hd2_auto_testdata_flag is pulled low, the signal generation module stops sending test signals and switches to the RF service signal of the RF port. The RF service signal and compensation parameters are sent to the compensation execution module for real-time second harmonic distortion correction; Step 6: When the compensation execution module detects that the compensation enable signal is valid and the calculation completion flag HD2_calc_done is completed, the compensation execution module performs the calculation on the RF service signal. The calculation process involves several steps: Step 7: Before the next parameter calibration, the compensation parameters maintain the previous calibration result. The compensation execution module continuously performs compensation and correction on the RF service signal when the compensation enable signal is valid. If the compensation enable signal is invalid, the compensation execution module is bypassed. The single-channel mode selection signal in the diagram can be used to select whether to calibrate both I and Q channels simultaneously, or only one channel. The channel selection signal in the diagram can be used in a multi-channel system to select which receiving channel to calibrate. The internal parameters of the hd2 iteration can refer to the internal intermediate variables or configuration parameters used by the control module during iterative algorithms such as gradient descent.

[0119] It should be noted that the nonlinear second harmonic distortion correction method of this invention only requires iterative calculation of the compensation coefficient based on the statistical characteristics of the test signal itself, resulting in low complexity and suitability for real-time processing. In terms of HD2 suppression capability, it can effectively eliminate the second harmonic to background noise and is suitable for wide and narrowband or time-varying channels. Specific application scenarios include satellite communication receivers, 4G LTE / 5G NR user terminals, and radar signal processing.

[0120] This embodiment discloses the acquisition and caching of a preset number of data points of the test signal; based on the preset number of data points, determining the skewness value of the output signal after nonlinear transformation of the test signal, and using the skewness value as the statistical distribution characteristic of the test signal; the nonlinear transformation includes compensation parameters to be determined; iteratively updating the compensation parameters with the optimization objective of minimizing the absolute value of the skewness value; when the absolute value of the skewness value satisfies a preset convergence condition during the iterative update process, the current compensation parameter is used as the compensation parameter for suppressing second harmonic distortion. Because this embodiment determines the skewness value of the output signal after nonlinear transformation of the test signal by caching a preset number of data points of the test signal, and then iteratively updates the compensation parameters with the optimization objective of minimizing the absolute value of the skewness value, compared with the prior art, this embodiment improves the robustness and applicability of the system.

[0121] refer to Figure 6 , Figure 6 This is a flowchart illustrating the third embodiment of the nonlinear second harmonic distortion correction method of the present invention.

[0122] Based on the above embodiments, in this embodiment, before step S30, steps S205~S207 are further included:

[0123] Step S205: Determine whether the compensation enable signal is valid.

[0124] Step S206: If the compensation enable signal is valid, then perform the step of nonlinear compensation of the radio frequency service signal based on the compensation parameters.

[0125] Step S207: If the compensation enable signal is invalid, the step of performing nonlinear compensation on the radio frequency service signal based on the compensation parameters is bypassed, and the radio frequency service signal is output.

[0126] It should be noted that the compensation enable signal can be a digital control signal, which is essentially a binary switch instruction used to command the compensation execution module in the digital signal processing link to be either active or bypassed.

[0127] It should be understood that in the event of unexpected calibration failures, abnormal compensation parameters, or extreme nonlinearity in the front-end circuitry, invalid compensation may severely distort or even interrupt the signal. Enable control provides an emergency shutdown or safety bypass mechanism to ensure that, in the worst-case scenario, the system can still bypass the faulty module, maintain basic signal paths and communication functions, and prevent a single module failure from rendering the entire system unusable.

[0128] This embodiment discloses a method for determining whether a compensation enable signal is valid. If the compensation enable signal is valid, a step of performing nonlinear compensation on the radio frequency service signal based on the compensation parameters is executed. If the compensation enable signal is invalid, the step of performing nonlinear compensation on the radio frequency service signal based on the compensation parameters is bypassed, and the radio frequency service signal is output. Because this embodiment determines whether to perform nonlinear compensation on the radio frequency service signal by judging whether the compensation enable signal is valid, compared to existing technologies, this embodiment improves the reliability and security of the system.

[0129] Furthermore, this embodiment of the invention also proposes a storage medium storing a nonlinear second harmonic distortion correction program, which, when executed by a processor, implements the steps of the nonlinear second harmonic distortion correction method described above.

[0130] Reference Figure 7 , Figure 7 This is a structural block diagram of the first embodiment of the nonlinear second harmonic distortion correction device of the present invention.

[0131] like Figure 7 As shown, the nonlinear second harmonic distortion correction device proposed in this embodiment of the invention includes: a signal generation module 501, a parameter determination module 502, and a signal processing module 503.

[0132] The signal generation module 501 is used to generate a test signal of a preset frequency in response to the calibration trigger signal after receiving the calibration trigger signal.

[0133] The parameter determination module 502 is used to determine compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal.

[0134] The signal processing module 503 is used to receive radio frequency service signals, perform nonlinear compensation on the radio frequency service signals based on the compensation parameters, and obtain and output the compensated radio frequency service signals.

[0135] The signal generation module 501 is further configured to generate a test signal acquisition request signal in response to the calibration trigger signal; based on the test signal acquisition request signal, control the auxiliary phase-locked loop to generate a single-frequency signal of a preset frequency, and use the single-frequency signal as a test signal.

[0136] This device embodiment discloses that, upon receiving a calibration trigger signal, it generates a test signal of a preset frequency in response to the calibration trigger signal; based on the statistical distribution characteristics of the test signal, it determines compensation parameters for suppressing second harmonic distortion; it receives an radio frequency (RF) service signal and performs nonlinear compensation on the RF service signal based on the compensation parameters, thereby obtaining and outputting the compensated RF service signal. Because this device embodiment generates a test signal in response to a calibration trigger signal, then determines the compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal, and finally performs nonlinear compensation on the RF service signal based on the compensation parameters, compared to existing technologies, this device embodiment effectively reduces computational complexity and improves real-time performance.

[0137] Based on the first embodiment of the nonlinear second harmonic distortion correction device of the present invention, a second embodiment of the nonlinear second harmonic distortion correction device of the present invention is proposed.

[0138] In this embodiment, the parameter determination module 502 is further configured to collect and cache a preset number of data points of the test signal; based on the preset number of data points, determine the skewness value of the output signal after the nonlinear transformation of the test signal, and use the skewness value as the statistical distribution characteristic of the test signal, wherein the nonlinear transformation includes compensation parameters to be determined; iteratively update the compensation parameters with the goal of minimizing the absolute value of the skewness value; when the absolute value of the skewness value satisfies a preset convergence condition during the iterative update process, use the current compensation parameter as the compensation parameter for suppressing second harmonic distortion.

[0139] The parameter determination module 502 is further configured to determine the mean and standard deviation of the output signal after the nonlinear transformation of the test signal based on the preset number of data points; determine the third central moment of the output signal based on the mean and the preset number of data points; determine the skewness value according to the third central moment and the standard deviation, and use the skewness value as the statistical distribution characteristic of the test signal.

[0140] The parameter determination module 502 is further configured to construct a cost function based on the absolute value of the skewness value, and determine the gradient of the cost function with respect to the compensation parameter; based on the gradient, update the compensation parameter using gradient descent until the absolute value of the skewness value satisfies a preset convergence condition.

[0141] The signal processing module 503 is further configured to receive radio frequency service signals, determine the in-phase branch signals and quadrature branch signals in the radio frequency service signals; perform nonlinear compensation on the in-phase branch signals and the quadrature branch signals respectively based on the compensation parameters to obtain the compensated in-phase branch signals and the compensated quadrature branch signals; and use the compensated in-phase branch signals and the compensated quadrature branch signals as the compensated radio frequency service signals.

[0142] Other embodiments or specific implementations of the nonlinear second harmonic distortion correction device of the present invention can be referred to the above-described method embodiments, and will not be repeated here.

[0143] This application provides a nonlinear second harmonic distortion correction device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the nonlinear second harmonic distortion correction method in Embodiment 1 above.

[0144] The following is for reference. Figure 8 This document illustrates a structural schematic diagram suitable for implementing a nonlinear second harmonic distortion correction device according to embodiments of this application. The nonlinear second harmonic distortion correction device in embodiments of this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), and in-vehicle terminals (e.g., in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers. Figure 8 The nonlinear second harmonic distortion correction device shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0145] like Figure 8As shown, the nonlinear second harmonic distortion correction device may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory 1002 or a program loaded from a storage device 1003 into a random access memory 1004. The random access memory 1004 also stores various programs and data required for the operation of the nonlinear second harmonic distortion correction device. The processing unit 1001, the read-only memory 1002, and the random access memory 1004 are interconnected via a bus 1005. An input / output interface 1006 is also connected to the bus. Typically, the following systems can be connected to the input / output interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the nonlinear second harmonic distortion correction device to communicate wirelessly or wiredly with other devices to exchange data. Although the figures show nonlinear second harmonic distortion correction devices with various systems, it should be understood that implementation or possession of all the systems shown is not required. More or fewer systems may be implemented alternatively.

[0146] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from read-only memory 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0147] The nonlinear second-harmonic distortion correction device provided in this application, employing the nonlinear second-harmonic distortion correction method described in the above embodiments, can solve the technical problems of high computational complexity and poor real-time performance in existing second-harmonic distortion correction technologies. Compared with the prior art, the beneficial effects of the nonlinear second-harmonic distortion correction device provided in this application are the same as those of the nonlinear second-harmonic distortion correction method provided in the above embodiments, and other technical features of this nonlinear second-harmonic distortion correction device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0148] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0149] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0150] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0151] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0152] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as read-only memory / random access memory, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0153] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the protection scope of the present invention.

Claims

1. A nonlinear second harmonic distortion correction method, characterized in that, The method includes: Upon receiving a calibration trigger signal, a test signal of a preset frequency is generated in response to the calibration trigger signal. Based on the statistical distribution characteristics of the test signal, compensation parameters for suppressing second harmonic distortion are determined. Receive radio frequency service signals, and perform nonlinear compensation on the radio frequency service signals based on the compensation parameters to obtain and output the compensated radio frequency service signals; The step of determining the compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal includes: Collect and cache a preset number of data points of the test signal; Based on the preset number of data points, the skewness value of the output signal after the nonlinear transformation of the test signal is determined, and the skewness value is used as the statistical distribution characteristic of the test signal. The nonlinear transformation includes compensation parameters to be determined. The compensation parameters are iteratively updated with the goal of minimizing the absolute value of the skewness. When the absolute value of the skewness value satisfies the preset convergence condition during the iterative update process, the current compensation parameter is used as the compensation parameter to suppress second harmonic distortion.

2. The nonlinear second harmonic distortion correction method as described in claim 1, characterized in that, The step of determining the skewness value of the output signal after nonlinear transformation of the test signal based on the preset number of data points, and using the skewness value as the statistical distribution characteristic of the test signal, includes: Based on the preset number of data points, the mean and standard deviation of the output signal after the nonlinear transformation of the test signal are determined; Based on the mean and the preset number of data points, the third central moment of the output signal is determined; The skewness value is determined based on the third central moment and the standard deviation, and the skewness value is used as the statistical distribution characteristic of the test signal.

3. The nonlinear second harmonic distortion correction method as described in claim 1, characterized in that, The step of iteratively updating the compensation parameters with the optimization objective of minimizing the absolute value of the skewness includes: A cost function is constructed based on the absolute value of the skewness value, and the gradient of the cost function with respect to the compensation parameter is determined. Based on the gradient, the compensation parameters are updated using gradient descent until the absolute value of the skewness value satisfies the preset convergence condition.

4. The nonlinear second harmonic distortion correction method as described in claim 1, characterized in that, The step of generating a test signal of a preset frequency in response to the calibration trigger signal after receiving the calibration trigger signal includes: In response to the calibration trigger signal, a test signal acquisition request signal is generated; Based on the test signal, a request signal is obtained, and the auxiliary phase-locked loop is controlled to generate a single-frequency signal of a preset frequency, and the single-frequency signal is used as the test signal.

5. The nonlinear second harmonic distortion correction method as described in claim 1, characterized in that, The step of receiving the radio frequency service signal, performing nonlinear compensation on the radio frequency service signal based on the compensation parameters, and obtaining and outputting the compensated radio frequency service signal includes: Receive radio frequency service signals and determine the in-phase branch signals and quadrature branch signals in the radio frequency service signals; Based on the compensation parameters, nonlinear compensation is performed on the in-phase branch signal and the quadrature branch signal respectively to obtain the compensated in-phase branch signal and the compensated quadrature branch signal. The compensated in-phase branch signal and the compensated quadrature branch signal are used as the compensated radio frequency service signal.

6. The nonlinear second harmonic distortion correction method according to any one of claims 1-5, characterized in that, Before the step of performing nonlinear compensation on the radio frequency service signal based on the compensation parameters, the method further includes: Determine whether the compensation enable signal is valid; If the compensation enable signal is valid, then the step of performing nonlinear compensation on the radio frequency service signal based on the compensation parameters is executed; If the compensation enable signal is invalid, the step of performing nonlinear compensation on the radio frequency service signal based on the compensation parameters is bypassed, and the radio frequency service signal is output.

7. A nonlinear second harmonic distortion correction device, characterized in that, The device includes: The signal generation module is used to generate a test signal of a preset frequency in response to the calibration trigger signal after receiving the calibration trigger signal. The parameter determination module is used to determine the compensation parameters for suppressing second harmonic distortion based on the statistical distribution characteristics of the test signal. The signal processing module is used to receive radio frequency service signals, perform nonlinear compensation on the radio frequency service signals based on the compensation parameters, and obtain and output the compensated radio frequency service signals. The parameter determination module is further configured to collect and cache a preset number of data points of the test signal; based on the preset number of data points, determine the skewness value of the output signal after the nonlinear transformation of the test signal, and use the skewness value as the statistical distribution characteristic of the test signal, wherein the nonlinear transformation includes compensation parameters to be determined; iteratively update the compensation parameters with the optimization objective of minimizing the absolute value of the skewness value; when the absolute value of the skewness value satisfies a preset convergence condition during the iterative update process, use the current compensation parameter as the compensation parameter for suppressing second harmonic distortion.

8. A nonlinear second harmonic distortion correction device, characterized in that, The device includes: a memory, a processor, and a nonlinear second harmonic distortion correction program stored in the memory and executable on the processor, the nonlinear second harmonic distortion correction program being configured to implement the steps of the nonlinear second harmonic distortion correction method as described in any one of claims 1 to 6.

9. A storage medium, characterized in that, The storage medium stores a nonlinear second harmonic distortion correction program, which, when executed by a processor, implements the steps of the nonlinear second harmonic distortion correction method as described in any one of claims 1 to 6.

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