CN116318210A - Compensation method, compensator and system for nonlinear distortion of pulse field source - Google Patents
Compensation method, compensator and system for nonlinear distortion of pulse field source Download PDFInfo
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Abstract
Description
技术领域technical field
本发明属于通信技术领域,具体涉及一种用于脉冲场源非线性失真的补偿方法、补偿器及系统。The invention belongs to the technical field of communication, and in particular relates to a compensation method, a compensator and a system for nonlinear distortion of a pulse field source.
背景技术Background technique
大功率脉冲场源工作在微波频段,用以产生高幅值脉冲辐射场,通常采用速调管、回旋管等电子真空器件,此类器件输出功率的线性度比较差,输出波形失真度各不相同,如何提高脉冲场源的线性度是亟需解决的重要难题。受限于电子真空器件自身物理结构和色散特性,很难从脉冲源本身提高其输出线性度,往往采用提高宽带接收机、混频器等接收设备线性度的方式来实现。但是宽带接收机中放大器、混频器等射频接收前端组件的三阶输出交调点等指标的不足将影响数字接收前端的线性度。与发射端的PA相比,数字接收机处的高速ADC通常因为非线性较弱而被当作是理想的设备。但实际中,接收机前端ADC带来的弱非线性依旧会导致激荡,且由于非线性较弱而难以被识别和校准。这会使得系统难以保证较大的无杂散动态范围SFDR而出现接收信号的非线性失真。在接收机出现非线性失真的情况下,系统的无杂散动态范围下降,采集到的弱信号就非常容易被强信号非线性失真分量或其他杂波所淹没。High-power pulsed field sources work in the microwave frequency band to generate high-amplitude pulsed radiation fields. Electronic vacuum devices such as klystrons and gyrotrons are usually used. The linearity of output power of such devices is relatively poor, and the degree of distortion of output waveforms varies. Similarly, how to improve the linearity of the pulsed field source is an important problem that needs to be solved urgently. Limited by the physical structure and dispersion characteristics of electronic vacuum devices, it is difficult to improve the output linearity of the pulse source itself, and it is often achieved by improving the linearity of receiving equipment such as broadband receivers and mixers. However, the lack of indicators such as the third-order output intermodulation point of RF receiving front-end components such as amplifiers and mixers in broadband receivers will affect the linearity of the digital receiving front-end. A high-speed ADC at a digital receiver is usually considered an ideal device due to its lower nonlinearity compared to the PA at the transmitter. But in practice, the weak nonlinearity brought by the front-end ADC of the receiver will still cause turbulence, and it is difficult to be identified and calibrated due to the weak nonlinearity. This will make it difficult for the system to ensure a large spurious-free dynamic range SFDR, and nonlinear distortion of the received signal will appear. In the case of nonlinear distortion in the receiver, the spurious-free dynamic range of the system decreases, and the collected weak signal is easily overwhelmed by the nonlinear distortion component of strong signal or other clutter.
对于高性能要求的宽带数字接收机而言,各模拟和模数混合器件的弱非线性同样会降低动态范围提升的可能,在强弱信号共存的情况下影响对微弱信号的检测能力。因此,设计高动态范围宽带数字接收机的首要任务是尽可能提高各器件的线性度。受现有工艺的制约,仅通过不断优化模拟电路很难达到理想的线性效果。利用某种数字补偿技术来降低接收机前端的非线性问题,是现阶段更为常用的方案。目前相关领域广泛采用的线性化技术大致有功率回退方法、反馈技术、前馈技术、预失真技术等,其中预失真技术被广泛应用于解决发射端非线性失真问题。若将预失真思想应用于接收端中,将RF射频前端和模数转换器ADC表现出来的非线性看作一个类似于PA的非线性系统,则补偿方案即为构造出类似数字预失真DPD后逆的补偿系统,保证整体呈现线性来达成接收端的线性化。For wideband digital receivers that require high performance, the weak nonlinearity of each analog and analog-digital hybrid device will also reduce the possibility of improving the dynamic range, and affect the ability to detect weak signals when strong and weak signals coexist. Therefore, the primary task of designing a wideband digital receiver with high dynamic range is to improve the linearity of each device as much as possible. Constrained by the existing technology, it is difficult to achieve the ideal linear effect only by continuously optimizing the analog circuit. It is a more commonly used solution at this stage to use some digital compensation technology to reduce the nonlinear problem of the front end of the receiver. At present, the linearization technologies widely used in related fields generally include power back-off method, feedback technology, feed-forward technology, pre-distortion technology, etc. Among them, pre-distortion technology is widely used to solve the problem of nonlinear distortion at the transmitter. If the pre-distortion idea is applied to the receiving end, and the nonlinearity shown by the RF front-end and the analog-to-digital converter ADC is regarded as a nonlinear system similar to PA, then the compensation scheme is to construct a similar digital pre-distortion DPD The inverse compensation system ensures the overall linearity to achieve the linearization of the receiving end.
然而进入非线性系统的输入信号为模拟信号,想要得到接收机的数字输入信号就需要额外增加一个模数转换器ADC将信号转换。这样的结构有三个缺点,其一,增加高速模数转换器ADC带来成本的上升;其二,想要直接将射频信号转换到基带作为参考信号需要ADC具有极高的采样率与转换精度;其三,新增的模数转换器ADC依然有非线性影响补偿效果。可见,现有技术不能在不添加额外模数转换器ADC的情况下,直接对接收机非线性进行补偿,也就难以在不添加额外模数转换器ADC的情况下采用提高接收设备线性度的方式来提高脉冲场源辐射信号的线性度。However, the input signal entering the nonlinear system is an analog signal, and to obtain the digital input signal of the receiver, an additional analog-to-digital converter ADC is required to convert the signal. Such a structure has three disadvantages. First, adding a high-speed analog-to-digital converter ADC brings about an increase in cost; second, if you want to directly convert the RF signal to the baseband as a reference signal, the ADC needs to have a very high sampling rate and conversion accuracy; Third, the newly added analog-to-digital converter ADC still has a nonlinear effect compensation effect. It can be seen that the existing technology cannot directly compensate the non-linearity of the receiver without adding an additional analog-to-digital converter ADC, and it is difficult to adopt the method of improving the linearity of the receiving device without adding an additional analog-to-digital converter ADC. Ways to improve the linearity of the pulsed field source radiation signal.
发明内容Contents of the invention
本发明的目的是提供一种用于脉冲场源非线性失真的补偿方法、补偿器及系统,以解决相关技术中针对脉冲场源非线性失真的问题,不能在不添加额外模数转换器ADC的情况下,直接对接收机非线性进行补偿的难题。The purpose of the present invention is to provide a compensation method, compensator and system for nonlinear distortion of pulsed field source, to solve the problem of nonlinear distortion of pulsed field source in the related art, without adding additional analog-to-digital converter ADC In the case of , it is a difficult problem to directly compensate the nonlinearity of the receiver.
为了实现上述目的,本发明第一个方面,提供了一种用于脉冲场源非线性失真的补偿方法,包括:In order to achieve the above object, the first aspect of the present invention provides a compensation method for nonlinear distortion of a pulsed field source, including:
采用作为泛函级数的Volterra级数构建用于模拟数字接收机非线性失真的Volterra级数模型,并将所述数字接收机接收到的待补偿信号载入所述Volterra级数模型获得失真信号,其中,所述失真信号携带有非线性失真量;Using the Volterra series as a functional series to construct a Volterra series model for simulating the nonlinear distortion of a digital receiver, and loading the signal to be compensated received by the digital receiver into the Volterra series model to obtain a distorted signal , wherein the distorted signal carries a nonlinear distortion amount;
根据所述Volterra级数模型,构建用于表征所述非线性失真量的补偿模型,所述补偿模型包括非线性记忆矩阵和补偿核向量,所述非线性记忆矩阵由所述Volterra级数模型构造的各阶次的记忆非线性列向量构成,所述补偿核向量由所述Volterra级数模型各阶次的核系数构成;According to the Volterra series model, construct a compensation model for characterizing the nonlinear distortion amount, the compensation model includes a nonlinear memory matrix and a compensation kernel vector, and the nonlinear memory matrix is constructed by the Volterra series model The memory nonlinear column vector of each order of each order is formed, and described compensation kernel vector is formed by the kernel coefficient of each order of described Volterra series model;
利用所述补偿模型消除所述失真信号中的所述非线性失真量,获得补偿输出;Using the compensation model to eliminate the nonlinear distortion in the distorted signal to obtain a compensation output;
基于所述补偿输出,采用最小二乘法更新所述补偿模型的所述补偿核向量,以利用所述补偿核向量更新后的所述补偿模型实时消除所述失真信号中的所述非线性失真量。Based on the compensation output, using the least squares method to update the compensation kernel vector of the compensation model, so as to eliminate the nonlinear distortion amount in the distorted signal in real time by using the compensation model updated by the compensation kernel vector .
进一步地,基于所述补偿输出,采用最小二乘法更新所述补偿模型的所述补偿核向量的步骤包括:Further, based on the compensation output, the step of using the least squares method to update the compensation kernel vector of the compensation model includes:
从所述补偿输出中提取出非线性失真分量,所述非线性失真分量为,第k个所述待补偿信号载入所述Volterra级数模型获得的所述失真信号中所述非线性失真量的值,k为正整数;A nonlinear distortion component is extracted from the compensation output, and the nonlinear distortion component is the nonlinear distortion amount in the distorted signal obtained by loading the kth signal to be compensated into the Volterra series model The value of k is a positive integer;
根据提取的k个所述非线性失真分量确定所述非线性失真量的非线性信号功率;determining the nonlinear signal power of the nonlinear distortion amount according to the extracted k nonlinear distortion components;
基于所述非线性信号功率,采用最小二乘法对所述补偿模型的所述补偿核向量进行迭代运算,获得数据更新后的所述补偿核向量,并将更新后的所述补偿核向量载入所述补偿模型,以利用所述补偿模型实时消除所述失真信号中的所述非线性失真量。Based on the nonlinear signal power, the least square method is used to iteratively calculate the compensation kernel vector of the compensation model to obtain the updated compensation kernel vector, and load the updated compensation kernel vector into The compensation model is used to eliminate the nonlinear distortion amount in the distorted signal in real time by using the compensation model.
进一步地,基于所述补偿输出,采用最小二乘法更新所述补偿模型的所述补偿核向量的步骤还包括:Further, based on the compensation output, the step of using the least squares method to update the compensation kernel vector of the compensation model further includes:
确定所述失真信号的功率谱密度,并根据所述功率谱密度确定所述非线性失真量的频段信息;determining the power spectral density of the distorted signal, and determining the frequency band information of the nonlinear distortion amount according to the power spectral density;
根据所述频段信息构造多通带滤波器;Constructing a multi-passband filter according to the frequency band information;
采用所述多通带滤波器从所述补偿输出中提取出所述非线性失真分量,所述非线性失真分量为,第k个所述待补偿信号载入所述Volterra级数模型获得的所述失真信号中所述非线性失真量的值,k为正整数;Using the multi-passband filter to extract the nonlinear distortion component from the compensation output, the nonlinear distortion component is obtained by loading the kth signal to be compensated into the Volterra series model The value of the nonlinear distortion amount in the distorted signal, k is a positive integer;
根据提取的k个所述非线性失真分量确定所述非线性失真量的非线性信号功率;determining the nonlinear signal power of the nonlinear distortion amount according to the extracted k nonlinear distortion components;
基于所述非线性信号功率,采用最小二乘法对所述补偿模型的所述补偿核向量进行迭代运算,获得数据更新后的所述补偿核向量,并将更新后的所述补偿核向量载入所述补偿模型,以利用所述补偿模型实时消除所述失真信号中的所述非线性失真量。Based on the nonlinear signal power, the least square method is used to iteratively calculate the compensation kernel vector of the compensation model to obtain the updated compensation kernel vector, and load the updated compensation kernel vector into The compensation model is used to eliminate the nonlinear distortion amount in the distorted signal in real time by using the compensation model.
进一步地,确定所述失真信号的功率谱密度,并根据所述功率谱密度确定所述非线性失真量的频段信息的步骤包括:Further, the step of determining the power spectral density of the distorted signal, and determining the frequency band information of the nonlinear distortion amount according to the power spectral density includes:
对所述失真信号进行离散傅里叶变换,获得所述功率谱密度,并根据所述功率谱密度绘制功率谱密度图;performing discrete Fourier transform on the distorted signal to obtain the power spectral density, and drawing a power spectral density diagram according to the power spectral density;
基于预先设置的功率谱门限,将所述功率谱密度图中第一个奈奎斯特频带内,位于所述功率谱门限之下的功率谱密度确定为所述非线性失真量的功率谱密度。Based on the preset power spectrum threshold, determine the power spectral density below the power spectrum threshold in the first Nyquist band in the power spectral density map as the power spectral density of the nonlinear distortion amount .
进一步地,基于所述非线性信号功率,采用最小二乘法对所述补偿模型的所述补偿核向量进行迭代运算的步骤包括:Further, based on the nonlinear signal power, the step of iteratively calculating the compensation kernel vector of the compensation model by using the least square method includes:
以最小化所述非线性信号功率的运算目标作为所述最小二乘法的代价函数,根据所述代价函数构造自相关矩阵;Taking the operation target of minimizing the nonlinear signal power as the cost function of the least squares method, constructing an autocorrelation matrix according to the cost function;
基于所述自相关矩阵的逆矩阵,采用最小二乘法对所述补偿模型的所述补偿核向量进行迭代运算。Based on the inverse matrix of the autocorrelation matrix, the least square method is used to iteratively calculate the compensation kernel vector of the compensation model.
本发明第二个方面,提供了一种面向数字接收机非线性失真的补偿器,包括:The second aspect of the present invention provides a compensator for nonlinear distortion of digital receivers, including:
非线性模拟模块,用于采用作为泛函级数的Volterra级数构建用于模拟数字接收机非线性失真的Volterra级数模型,并将所述数字接收机接收到的待补偿信号载入所述Volterra级数模型获得失真信号,其中,所述失真信号携带有非线性失真量;The nonlinear simulation module is used to construct a Volterra series model for simulating the nonlinear distortion of a digital receiver by using the Volterra series as a functional series, and load the signal to be compensated received by the digital receiver into the The Volterra series model obtains a distorted signal, wherein the distorted signal carries a nonlinear distortion amount;
补偿模型构建模块,用于根据所述Volterra级数模型,构建用于表征所述非线性失真量的补偿模型,所述补偿模型包括非线性记忆矩阵和补偿核向量,所述非线性记忆矩阵由所述Volterra级数模型构造的各阶次的记忆非线性列向量构成,所述补偿核向量由所述Volterra级数模型各阶次的核系数构成;Compensation model construction module, for according to described Volterra series model, constructs the compensation model for characterizing described nonlinear distortion amount, described compensation model comprises nonlinear memory matrix and compensation kernel vector, and described nonlinear memory matrix is composed of The memory nonlinear column vector of each order of described Volterra series model construction is formed, and described compensation kernel vector is formed by the nuclear coefficient of each order of described Volterra series model;
补偿输出获取模块,用于利用所述补偿模型消除所述失真信号中的所述非线性失真量,获得补偿输出;A compensation output acquisition module, configured to use the compensation model to eliminate the nonlinear distortion in the distorted signal to obtain a compensation output;
实时消除模块,用于基于所述补偿输出,采用最小二乘法更新所述补偿模型的所述补偿核向量,以利用所述补偿核向量更新后的所述补偿模型实时消除所述失真信号中的所述非线性失真量。A real-time elimination module, configured to update the compensation kernel vector of the compensation model by using the least squares method based on the compensation output, so as to eliminate the distortion in the distorted signal in real time by using the compensation model updated by the compensation kernel vector The nonlinear distortion amount.
进一步地,所述实时消除模块包括:Further, the real-time elimination module includes:
提取单元,用于从所述补偿输出中提取出非线性失真分量,所述非线性失真分量为,第k个所述待补偿信号载入所述Volterra级数模型获得的所述失真信号中所述非线性失真量的值,k为正整数;An extraction unit, configured to extract a nonlinear distortion component from the compensation output, where the nonlinear distortion component is obtained by loading the kth signal to be compensated into the distortion signal obtained by the Volterra series model The value of the nonlinear distortion amount, k is a positive integer;
确定单元,用于根据提取的k个所述非线性失真分量确定所述非线性失真量的非线性信号功率;a determining unit, configured to determine the nonlinear signal power of the nonlinear distortion amount according to the extracted k nonlinear distortion components;
迭代运算单元,用于基于所述非线性信号功率,采用最小二乘法对所述补偿模型的所述补偿核向量进行迭代运算,获得数据更新后的所述补偿核向量,并将更新后的所述补偿核向量载入所述补偿模型,以利用所述补偿模型实时消除所述失真信号中的所述非线性失真量。An iterative operation unit, configured to perform an iterative operation on the compensation kernel vector of the compensation model by using the least squares method based on the nonlinear signal power, to obtain the updated compensation kernel vector, and to obtain the updated compensation kernel vector. The compensation kernel vector is loaded into the compensation model, so as to eliminate the nonlinear distortion in the distorted signal in real time by using the compensation model.
进一步地,所述实时消除模块还包括:Further, the real-time elimination module also includes:
频段确定单元,用于确定所述失真信号的功率谱密度,并根据所述功率谱密度确定所述非线性失真量的频段信息;a frequency band determining unit, configured to determine the power spectral density of the distorted signal, and determine the frequency band information of the nonlinear distortion amount according to the power spectral density;
滤波器构造单元,用于根据所述频段信息构造多通带滤波器;a filter construction unit, configured to construct a multi-passband filter according to the frequency band information;
提取单元,用于采用所述多通带滤波器从所述补偿输出中提取出所述非线性失真分量,所述非线性失真分量为,第k个所述待补偿信号载入所述Volterra级数模型获得的所述失真信号中所述非线性失真量的值,k为正整数;An extraction unit, configured to extract the nonlinear distortion component from the compensation output by using the multi-passband filter, the nonlinear distortion component is, and the kth signal to be compensated is loaded into the Volterra stage The value of the nonlinear distortion amount in the distorted signal obtained by the numerical model, k is a positive integer;
确定单元,用于根据提取的k个所述非线性失真分量确定所述非线性失真量的非线性信号功率;a determining unit, configured to determine the nonlinear signal power of the nonlinear distortion amount according to the extracted k nonlinear distortion components;
迭代运算单元,用于基于所述非线性信号功率,采用最小二乘法对所述补偿模型的所述补偿核向量进行迭代运算,获得数据更新后的所述补偿核向量,并将更新后的所述补偿核向量载入所述补偿模型,以利用所述补偿模型实时消除所述失真信号中的所述非线性失真量。An iterative operation unit, configured to perform an iterative operation on the compensation kernel vector of the compensation model by using the least squares method based on the nonlinear signal power, to obtain the updated compensation kernel vector, and to obtain the updated compensation kernel vector. The compensation kernel vector is loaded into the compensation model, so as to eliminate the nonlinear distortion in the distorted signal in real time by using the compensation model.
本发明第三个方面,提供了一种信号补偿系统,包括:A third aspect of the present invention provides a signal compensation system, including:
数字接收机,所述数字接收机包括面向数字接收机非线性失真的补偿器;a digital receiver comprising a compensator for non-linear distortion of the digital receiver;
脉冲场源,所述脉冲场源用于产生脉冲辐射信号;a pulsed field source for generating a pulsed radiation signal;
所述数字接收机接收所述脉冲辐射信号,并将所述脉冲辐射信号作为待补偿信号载入所述面向数字接收机非线性失真的补偿器。The digital receiver receives the pulsed radiation signal, and loads the pulsed radiation signal as a signal to be compensated into the compensator for nonlinear distortion of the digital receiver.
进一步地,所述数字接收机还包括:Further, the digital receiver also includes:
射频前端;RF front end;
模数转换器,所述模数转换器的输入端与所述射频前端的输出端电连接,所述模数转换器的输出端与所述面向数字接收机非线性失真的补偿器电连接。An analog-to-digital converter, the input end of the analog-to-digital converter is electrically connected to the output end of the radio frequency front end, and the output end of the analog-to-digital converter is electrically connected to the compensator for nonlinear distortion of the digital receiver.
相对于现有技术而言,本申请提供的技术方案至少具备如下技术效果:Compared with the prior art, the technical solution provided by this application has at least the following technical effects:
本发明无需额外增加模数转换器ADC采集原始输入数据,直接对数字接收机接收到的信号进行补偿,无需求得原输入信号仍然能大量消除数字接收机的非线性失真,通过识别非线性分量的频率分布,构造滤波器提取出非线性量,构造出补偿信号中非线性失真量信号能量的代价函数并以此辨识更新补偿模型参数,该方法无需增加额外ADC来获取实际输入信号,而能够较好的改善信号补偿系统的无杂散动态范围SFDR性能。The present invention does not need to add additional analog-to-digital converter ADC to collect the original input data, directly compensates the signal received by the digital receiver, does not need to obtain the original input signal, and can still eliminate the nonlinear distortion of the digital receiver in large quantities, by identifying the nonlinear component The frequency distribution of the frequency distribution, the filter is constructed to extract the nonlinear quantity, and the cost function of the nonlinear distortion signal energy in the compensation signal is constructed to identify and update the compensation model parameters. This method does not need to add an additional ADC to obtain the actual input signal, but can Better improve the SFDR performance of the signal compensation system.
附图说明Description of drawings
构成本申请的一部分的说明书附图用来提供对本发明的进一步理解,本发明的示意性实施例及其说明用于解释本发明,并不构成对本发明的不当限定。在附图中:The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:
图1为本发明一实施例提供的一种用于脉冲场源非线性失真的补偿方法的流程示意图;Fig. 1 is a schematic flowchart of a compensation method for nonlinear distortion of a pulsed field source provided by an embodiment of the present invention;
图2为图1为中步骤S14的具体执行流程意图;Fig. 2 is the specific execution flow diagram of step S14 in Fig. 1;
图3为本发明一实施例提供的一种用于脉冲场源非线性失真的补偿器的结构示意图;Fig. 3 is a schematic structural diagram of a compensator for nonlinear distortion of a pulsed field source provided by an embodiment of the present invention;
图4为本发明一实施例提供的信号补偿系统的结构示意图;FIG. 4 is a schematic structural diagram of a signal compensation system provided by an embodiment of the present invention;
图5为本发明一实施例建立的非线性后补偿结构图;FIG. 5 is a structural diagram of nonlinear post-compensation established by an embodiment of the present invention;
图6为本发明一实施例数字接收机的后补偿仿真实验步骤示意图;6 is a schematic diagram of post-compensation simulation experiment steps of a digital receiver according to an embodiment of the present invention;
图7为本发明一实施例中仿真双音信号非线性失真的功率谱图;Fig. 7 is a power spectrum diagram of the nonlinear distortion of the simulated two-tone signal in an embodiment of the present invention;
图8为本发明一实施例提供的补偿模型自适应参数更新流程图;Fig. 8 is a flow chart of updating the adaptive parameters of the compensation model provided by an embodiment of the present invention;
图9为图6进行仿真补偿后输出信号的功率谱图。FIG. 9 is a power spectrum diagram of the output signal after simulation compensation in FIG. 6 .
附图标记说明:Explanation of reference signs:
10、数字接收机;11、补偿器;111、非线性模拟模块;112、补偿模型构建模块;113、补偿输出获取模块;114、实时消除模块;141、频段确定单元;142、滤波器构造单元;143、提取单元;144、确定单元;145、迭代运算单元;12、模数转换器;13、射频前端;20、脉冲场源。10. Digital receiver; 11. Compensator; 111. Nonlinear analog module; 112. Compensation model construction module; 113. Compensation output acquisition module; 114. Real-time elimination module; 141. Frequency band determination unit; 142.
具体实施方式Detailed ways
以下结合附图和具体实施例对本发明作进一步详细说明,根据下面说明和权利要求书,本发明的优点和特征将更清楚。需要说明的是,附图均采用非常简化的形式且均适用非精准的比例,仅用以方便、明晰地辅助说明本发明实施例的目的。The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description and claims, the advantages and features of the present invention will be more clear. It should be noted that all the drawings are in very simplified form and inaccurate scales, and are only used to facilitate and clearly assist the purpose of illustrating the embodiments of the present invention.
需要说明的是,为了清楚地说明本发明的内容,本发明特举多个实施例以进一步阐释本发明的不同实现方式,其中,该多个实施例是列举式而非穷举式。此外,为了说明的简洁,前实施例中已提及的内容往往在后实施例中予以省略,因此,后实施例中未提及的内容可相应参考前实施例。It should be noted that, in order to clearly illustrate the content of the present invention, the present invention specifically cites multiple embodiments to further explain different implementation modes of the present invention, wherein the multiple embodiments are enumerated rather than exhaustive. In addition, for the sake of brevity of description, the content mentioned in the previous embodiment is often omitted in the latter embodiment, therefore, the content not mentioned in the later embodiment can refer to the previous embodiment accordingly.
本发明第一个实施例,提供了一种用于脉冲场源非线性失真的补偿方法,如图1所示,该补偿方法包括如下步骤:The first embodiment of the present invention provides a compensation method for nonlinear distortion of a pulsed field source, as shown in Figure 1, the compensation method includes the following steps:
步骤S11:采用作为泛函级数的Volterra级数构建用于模拟数字接收机10非线性失真的Volterra级数模型,并将数字接收机10接收到的待补偿信号载入Volterra级数模型获得失真信号,其中,失真信号携带有非线性失真量。Step S11: using the Volterra series as a functional series to construct a Volterra series model for simulating the nonlinear distortion of the
步骤S12:根据Volterra级数模型,构建用于表征非线性失真量的补偿模型,补偿模型包括非线性记忆矩阵和补偿核向量,非线性记忆矩阵由Volterra级数模型构造的各阶次的记忆非线性列向量构成,补偿核向量由Volterra级数模型各阶次的核系数构成。Step S12: According to the Volterra series model, construct a compensation model for characterizing the amount of nonlinear distortion. The compensation model includes a nonlinear memory matrix and a compensation kernel vector. The nonlinear memory matrix is constructed by the Volterra series model. The linear column vector is formed, and the compensation kernel vector is formed by the kernel coefficients of each order of the Volterra series model.
步骤S13:利用补偿模型消除失真信号中的非线性失真量,获得补偿输出。Step S13: Using the compensation model to eliminate the nonlinear distortion in the distorted signal to obtain a compensation output.
步骤S14:基于补偿输出,采用最小二乘法更新补偿模型的补偿核向量,以利用补偿核向量更新后的补偿模型实时消除失真信号中的非线性失真量。Step S14: based on the compensation output, update the compensation kernel vector of the compensation model by using the least squares method, so as to eliminate the nonlinear distortion in the distorted signal in real time by using the compensation model updated by the compensation kernel vector.
具体而言,由于宽带数字接收机10记忆效应尤为明显,Volterra级数作为泛函级数,理论上可以模拟出一切可以用连续泛函描述的系统,是常用的记忆非线性模型,具有普适性,因此本发明实施例采用离散Volterra级数模型来模拟数字接收机10非线性失真,Volterra级数模型的表达式为:Specifically, since the memory effect of wideband
式中,x(k)是第k个离散的输入信号(即待补偿信号),k为正整数,y(k)是x(k)进入Volterra级数模型后的对应输出,d为输入的非线性阶数,D是d的最大值。Nd为第d阶Volterra核的最大记忆深度。h(r1,r2,…,rd)是第d阶Volterra级数对应的核系数。Volterra级数模型的核系数总数为:In the formula, x(k) is the kth discrete input signal (that is, the signal to be compensated), k is a positive integer, y(k) is the corresponding output of x(k) after entering the Volterra series model, and d is the input The nonlinear order, D is the maximum value of d. N d is the maximum memory depth of the dth order Volterra kernel. h(r 1 , r 2 ,..., r d ) is the kernel coefficient corresponding to the dth order Volterra series. The total number of kernel coefficients for the Volterra series model is:
实际中,随着记忆深度增加,信号幅度会有所衰减,而衰减后项的高阶非线性失真对系统线性的影响锐减。对于接收机而言,对系统的无杂散动态范围影响最大的是低阶非线性失真。因此,可采用低阶短记忆效应的Volterra级数模型模拟接收机的非线性失真,例如,取第2、3阶项的最大记忆深度为2的Volterra级数模型。In practice, as the memory depth increases, the signal amplitude will be attenuated, and the impact of the high-order nonlinear distortion of the attenuated term on the linearity of the system will decrease sharply. For the receiver, it is the low-order nonlinear distortion that has the greatest impact on the spurious-free dynamic range of the system. Therefore, the Volterra series model of the low-order short memory effect can be used to simulate the nonlinear distortion of the receiver, for example, the Volterra series model with the maximum memory depth of the second and third order items being 2.
步骤S12中的补偿模型应尽可能模拟出数字接收机10的非线性失真,因此,补偿模型采用与步骤S11中Volterra级数模型相似的结构,来表征失真信号的非线性记忆部分。补偿模型B(k)的表达式为:The compensation model in step S12 should simulate the nonlinear distortion of the
B(k)=AT(k)×w。B(k)= AT (k)×w.
式中的T为矩阵的转置运算符,定义表征非线性记忆部分的矩阵AT(k)(即非线性记忆矩阵),为G*N矩阵,其中A(k)的表达式为:T in the formula is the transposition operator of the matrix, defining the matrix A T (k) representing the nonlinear memory part (that is, the nonlinear memory matrix), which is a G*N matrix, where the expression of A(k) is:
A(k)=[v(k-G+1)v(k-G+2)…v(k-1)v(k)]。A(k)=[v(k-G+1)v(k-G+2)...v(k-1)v(k)].
其中v(k)是由y(k)构造的每一阶不包含线性项的记忆非线性列向量,w是待识别的补偿核向量。Where v(k) is a memory nonlinear column vector constructed by y(k) at each order that does not contain linear items, and w is the compensation kernel vector to be identified.
v(k)=[y2(k)y(k)y(k-1)…y2(k-Nd+1)y3(k)y2(k)y(k-1)…yD(k-Nd+1)]T。v(k)=[y 2 (k)y(k)y(k-1)...y 2 (kN d +1)y 3 (k)y 2 (k)y(k-1)...y D ( kN d +1)] T .
w=[h(0,0)h(0,1)…h(N2-1,N2-1)h(0,0,0)h(0,0,1)…h(ND-1,…,ND-1)]T,式中h为Volterra级数模型表达式展开获得的各阶次的核系数。w=[h(0,0)h(0,1)...h(N 2 -1,N 2 -1)h(0,0,0)h(0,0,1)...h(N D - 1,..., ND -1)] T , where h is the kernel coefficient of each order obtained by expanding the Volterra series model expression.
步骤S13中利用补偿模型消除失真信号中的非线性失真量,获得的补偿输出为:s(k)=y(k)-B(k),其中,为便于后续的计算,将A(k)与y(k)取相同长度的记忆部分以便后续计算,由此,y(k)的表达式可表示为:In step S13, the compensation model is used to eliminate the nonlinear distortion in the distorted signal, and the obtained compensation output is: s(k)=y(k)-B(k), wherein, for the convenience of subsequent calculation, A(k) Take the memory part of the same length as y(k) for subsequent calculation, thus, the expression of y(k) can be expressed as:
y(k)=[y(k-G+1)y(k-G+2)…y(k-1)y(k)]T,由于A(k)中的v(k)是由y(k)构造的记忆非线性列向量,y(k)表达式中的y(k)是由x(k)经过记忆非线性处理的量。y(k)=[y(k-G+1)y(k-G+2)…y(k-1)y(k)] T , since v(k) in A(k) is determined by y (k) The memory nonlinear column vector constructed, y(k) in the expression of y(k) is the quantity processed by x(k) through memory nonlinearity.
如图2所示,步骤S14中,基于补偿输出,采用最小二乘法更新补偿模型的补偿核向量的步骤包括:As shown in Figure 2, in step S14, based on the compensation output, the step of updating the compensation kernel vector of the compensation model using the least squares method includes:
步骤S141:确定失真信号的功率谱密度,并根据功率谱密度确定非线性失真量的频段信息。Step S141: Determine the power spectral density of the distorted signal, and determine the frequency band information of the nonlinear distortion according to the power spectral density.
步骤S142:根据频段信息构造多通带滤波器。Step S142: Construct a multi-passband filter according to the frequency band information.
步骤S143:采用多通带滤波器从补偿输出中提取出非线性失真分量,非线性失真分量为,第k个待补偿信号载入Volterra级数模型获得的失真信号中非线性失真量的值。Step S143: Using a multi-passband filter to extract the nonlinear distortion component from the compensation output, the nonlinear distortion component is the value of the nonlinear distortion amount in the distortion signal obtained by loading the kth signal to be compensated into the Volterra series model.
步骤S144:根据提取的k个非线性失真分量确定非线性失真量的非线性信号功率。Step S144: Determine the nonlinear signal power of the nonlinear distortion amount according to the extracted k nonlinear distortion components.
步骤S145:基于非线性信号功率,采用最小二乘法对补偿模型的补偿核向量进行迭代运算,获得数据更新后的补偿核向量,并将更新后的补偿核向量载入补偿模型,以利用补偿模型实时消除失真信号中的非线性失真量。Step S145: Based on the nonlinear signal power, the least square method is used to iteratively calculate the compensation kernel vector of the compensation model to obtain the updated compensation kernel vector of the data, and load the updated compensation kernel vector into the compensation model to utilize the compensation model Removes the amount of nonlinear distortion from distorted signals in real time.
步骤S141中,确定失真信号的功率谱密度,并根据功率谱密度确定非线性失真量的频段信息的步骤包括:对失真信号进行离散傅里叶变换,获得功率谱密度,并根据功率谱密度绘制功率谱密度图,基于预先设置的功率谱门限,将功率谱密度图中第一个奈奎斯特频带内,位于功率谱门限之下的功率谱密度确定为非线性失真量的功率谱密度。具体地,对于宽带数字接收机10整个接收频段而言,接收到的强信号通常分布的较为稀疏,而数字接收机10系统的非线性失真分量可以认为主要由强信号带来。对失真信号求N点离散傅里叶变换,求取失真信号的功率谱密度,功率谱密度表达式为:In step S141, the step of determining the power spectral density of the distorted signal, and determining the frequency band information of the nonlinear distortion according to the power spectral density includes: performing discrete Fourier transform on the distorted signal to obtain the power spectral density, and drawing according to the power spectral density The power spectral density graph is based on a preset power spectral threshold, and the power spectral density below the power spectral threshold in the first Nyquist band in the power spectral density graph is determined as the power spectral density of the nonlinear distortion. Specifically, for the entire receiving frequency band of the wideband
然后绘制出失真信号的功率谱密度图,设置合适的功率谱门限Phold,则可认为功率谱密度图中第一个奈奎斯特频带内功率谱密度超出功率谱门限Phold的信号就是要接收的强信号。在功率谱门限Phold之下的弱信号可以认为是非线性失真量,由此可以得到非线性失真的大致分布频段。Then draw the power spectral density diagram of the distorted signal, and set an appropriate power spectral threshold P hold , then it can be considered that the signal whose power spectral density exceeds the power spectral threshold P hold in the first Nyquist band in the power spectral density diagram is to be Strong signal received. The weak signal below the power spectrum threshold P hold can be considered as the amount of nonlinear distortion, and thus the approximate distribution frequency band of the nonlinear distortion can be obtained.
为了使得补偿后数字接收机10的非线性失真量得到抑制甚至消除,步骤S145中,基于非线性信号功率,采用最小二乘法对补偿模型的补偿核向量进行迭代运算的步骤包括:以最小化非线性信号功率的运算目标作为最小二乘法的代价函数,根据代价函数构造自相关矩阵,基于自相关矩阵的逆矩阵,采用最小二乘法对补偿模型的补偿核向量进行迭代运算。由于矩阵求逆在一些硬件实现上具有局限性,本发明实施例在具体运算时,可将自相关矩阵的逆矩阵采用代价函数的互相关向量来代替计算。在获得更新后的补偿核向量后,将更新后的补偿核向量载入补偿模型,来消除非线性失真量。In order to suppress or even eliminate the nonlinear distortion of the
本发明实施例提供的补偿方法无需额外增加模数转换器ADC采集原始输入数据,直接对数字接收机10接收到的信号进行补偿,无需求得原输入信号仍然能大量消除数字接收机10的非线性失真,通过识别非线性分量的频率分布,构造滤波器提取出非线性量,构造出补偿信号中非线性失真量信号能量的代价函数并以此辨识更新补偿模型参数,该方法无需增加额外ADC来获取实际输入信号,而能够较好的改善系统无杂散动态范围SFDR性能。The compensation method provided by the embodiment of the present invention does not need to add an additional analog-to-digital converter ADC to collect the original input data, and directly compensates the signal received by the
本发明第二个实施例,提供了一种用于脉冲场源非线性失真的补偿器,如图3所示,包括非线性模拟模块111、补偿模型构建模块112、补偿输出获取模块113以及实时消除模块114。其中,非线性模拟模块111用于采用作为泛函级数的Volterra级数构建用于模拟数字接收机10非线性失真的Volterra级数模型,并将数字接收机10接收到的待补偿信号载入Volterra级数模型获得失真信号,其中,失真信号携带有非线性失真量。补偿模型构建模块112,用于根据Volterra级数模型,构建用于表征非线性失真量的补偿模型,补偿模型包括非线性记忆矩阵和补偿核向量,非线性记忆矩阵由Volterra级数模型构造的各阶次的记忆非线性列向量构成,补偿核向量由Volterra级数模型各阶次的核系数构成。补偿输出获取模块113,用于利用补偿模型消除失真信号中的非线性失真量,获得补偿输出。实时消除模块114,用于基于补偿输出,采用最小二乘法更新补偿模型的补偿核向量,以利用补偿核向量更新后的补偿模型实时消除失真信号中的非线性失真量。The second embodiment of the present invention provides a compensator for nonlinear distortion of a pulsed field source, as shown in Figure 3, including a nonlinear simulation module 111, a compensation
其中,实时消除模块114主要包括提取单元143、确定单元144以及迭代运算单元145,其中,提取单元143用于从补偿输出中提取出非线性失真分量,非线性失真分量为,第k个待补偿信号载入Volterra级数模型获得的失真信号中非线性失真量的值。确定单元144用于根据提取的k个非线性失真分量确定非线性失真量的非线性信号功率。迭代运算单元145用于基于非线性信号功率,采用最小二乘法对补偿模型的补偿核向量进行迭代运算,获得数据更新后的补偿核向量,并将更新后的补偿核向量载入补偿模型,以利用补偿模型实时消除失真信号中的非线性失真量。Wherein, the real-
在本发明实施例一具体应用实例中,实时消除模块114还包括频段确定单元141和频段确定单元141,频段确定单元141用于确定失真信号的功率谱密度,并根据功率谱密度确定非线性失真量的频段信息。滤波器构造单元142用于根据频段信息构造多通带滤波器。提取单元143,用于采用滤波器构造单元142构造的多通带滤波器从补偿输出中提取出非线性失真分量,非线性失真分量为,第k个待补偿信号载入Volterra级数模型获得的失真信号中非线性失真量的值。确定单元144用于根据提取的k个非线性失真分量确定非线性失真量的非线性信号功率。迭代运算单元145,用于基于非线性信号功率,采用最小二乘法对补偿模型的补偿核向量进行迭代运算,获得数据更新后的补偿核向量,并将更新后的补偿核向量载入补偿模型,以利用补偿模型实时消除失真信号中的非线性失真量。In a specific application example of the embodiment of the present invention, the real-
本发明第三个实施例,提供了一种信号补偿系统,如图4所示,该信号补偿系统包括脉冲场源20和数字接收机10,脉冲场源20用于产生脉冲辐射信号,数字接收机10包括面向数字接收机10非线性失真的补偿器11。数字接收机10接收脉冲辐射信号,并将脉冲辐射信号作为待补偿信号载入面向数字接收机10非线性失真的补偿器11,从而在不添加额外模数转换器ADC的情况下采用提高数字接收机10线性度的方式来提高脉冲场源20辐射信号的线性度。The third embodiment of the present invention provides a signal compensation system, as shown in Figure 4, the signal compensation system includes a
数字接收机10还包括射频前端13和模数转换器12,模数转换器12的输入端与射频前端13的输出端电连接,模数转换器12的输出端与面向数字接收机10非线性失真的补偿器11电连接。射频前端13接收脉冲场源20产生的脉冲辐射信号并发送至模数转换器12,由模数转换器12将脉冲辐射信号转换成数字信号后作为待补偿信号发送给补偿器11来进行补偿处理,从而消除脉冲辐射信号中的非线性失真量,改善信号补偿系统的无杂散动态范围SFDR性能。The
本发明第四个实施例结合上述三个实施例及附图1至附图9,针对宽带数字接收机10中存在的非线性失真问题,提出了一种基于最小二乘法的后补偿模型构建方法,利用补偿模型来消除信号的非线性失真分量复原出接收信号的应用实施例。In the fourth embodiment of the present invention, in combination with the above three embodiments and accompanying
本发明实施例基于最小二乘法的后补偿模型构建方法,具体步骤如下:The embodiment of the present invention is based on the post-compensation model construction method of the least square method, and the specific steps are as follows:
步骤一、选择合适的非线性模型来模拟数字接收机10的射频前端13与模数转换器12(本发明实施例在下文中将模数转换器12简称为ADC)的非线性失真,载入原信号,得到失真信号,如图5所示。
由于大多数的收发机都具有一定的记忆效应,对于宽带数字接收机10而言记忆效应尤为明显。本发明实施例选择离散Volterra级数模型来模拟数字接收机10的射频前端13与模数转换器12的非线性失真,Volterra级数模型表达式为:Since most transceivers have a certain memory effect, the memory effect is particularly obvious for the wideband
式中,x(k)是第k个离散的输入信号(即输入的第k个离散的待补偿信号),y(k)是x(k进入Volterra级数模型的对应输出,d为输入的非线性阶数,D是d的最大值,Nd为第d阶Volterra核的最大记忆深度,h(r1,r2,…,rd)是第d阶Volterra对应的核系数。模型核系数总数为:In the formula, x(k) is the kth discrete input signal (that is, the kth discrete input signal to be compensated), y(k) is the corresponding output of x(k entering the Volterra series model, d is the input Non-linear order, D is the maximum value of d, N d is the maximum memory depth of the d-th order Volterra kernel, h(r 1 , r 2 ,..., r d ) is the kernel coefficient corresponding to the d-th order Volterra. Model kernel The total number of coefficients is:
实际中,随着记忆深度增加,信号幅度会有所衰减,而衰减后项的高阶非线性失真对系统线性的影响锐减。对于数字接收机10而言,对系统的无杂散动态范围影响最大的是低阶非线性失真。因此,可采用低阶短记忆效应的Volterra级数模型模拟系统失真。例如,取第2、3阶项的最大记忆深度为2的Volterra级数模型模拟数字接收机10的非线性失真。In practice, as the memory depth increases, the signal amplitude will be attenuated, and the impact of the high-order nonlinear distortion of the attenuated term on the linearity of the system will decrease sharply. For
步骤二、辨识强信号与失真信号。对于宽带数字接收机10整个接收频段而言,接收到的强信号通常分布的较为稀疏,而接收机系统的非线性失真分量可以认为主要由强信号带来。对失真信号求N点离散傅里叶变换,求取失真信号的功率谱密度。功率谱密度表达式为:
绘制出失真信号的功率谱密度图,设置合适的功率谱门限Phold,则可认为功率谱密度图中第一个奈奎斯特频带内功率谱密度超出阈值Phold的信号就是要接收的强信号。在阈值Phold之下的弱信号可以认为是非线性失真量,由此可以得到非线性失真量的大致分布频段。由非线性失真量的频率信息(或者说频段信息),构造多通带滤波器,得到滤波器系数,将滤波器系数的FIR抽头系数向量定义为g=[g0g1…gG-1]T,矩阵维数为G*l,T为转置运算符。Draw the power spectral density diagram of the distorted signal, and set an appropriate power spectrum threshold P hold , then it can be considered that the signal whose power spectral density exceeds the threshold P hold in the first Nyquist band in the power spectral density diagram is the strong signal to be received. Signal. Weak signals below the threshold P hold can be considered as nonlinear distortion, and thus the approximate distribution frequency bands of the nonlinear distortion can be obtained. Construct a multi-passband filter by the frequency information (or frequency band information) of the nonlinear distortion amount to obtain the filter coefficients, and define the FIR tap coefficient vector of the filter coefficients as g=[g 0 g 1 ...g G-1 ] T , the matrix dimension is G*l, and T is the transpose operator.
步骤三、非线性失真量的补偿模型应尽可能模拟出系统的非线性失真,因此,补偿模型采用与步骤一中Volterra级数模型相似的结构,来表征非线性记忆部分。补偿模型B(k)的表达式为
B(k)=AT(k)×wB(k)= AT (k)×w
定义表征补偿系统非线性记忆部分的矩阵AT(k),为G*N矩阵Define the matrix A T (k) representing the nonlinear memory part of the compensation system, which is a G*N matrix
A(k)=[v(k-G+1)v(k-G+2)…v(k-1)v(k)]A(k)=[v(k-G+1)v(k-G+2)...v(k-1)v(k)]
定义其中v(k)是由y(k)构造的每一阶不包含线性项的记忆非线性列向量,w是待识别的补偿模型的补偿核向量。Definition where v(k) is a memory nonlinear column vector constructed by y(k) at each order that does not contain linear terms, and w is the compensation kernel vector of the compensation model to be identified.
v(k)=[y2(k)y(k)y(k-1)…y2(k-Nd+1)y3(k)y2(k)y(k-1)…yD(k-Nd+1)]T。v(k)=[y 2 (k)y(k)y(k-1)...y 2 (kN d +1)y 3 (k)y 2 (k)y(k-1)...y D ( kN d +1)] T .
w=[h(0,0)h(0,1)…h(N2-1,N2-1)h(0,0,0)h(0,0,1)…h(ND-1,…,ND-1)]T。w=[h(0,0)h(0,1)...h(N 2 -1,N 2 -1)h(0,0,0)h(0,0,1)...h(N D - 1,...,N D -1)] T .
补偿后得到的补偿输出为:s(k)=y(k)-B(k),其中:The compensation output obtained after compensation is: s(k)=y(k)-B(k), where:
y(k)=[y(k-G+1)y(k-G+2)…y(k-1)y(k)]T y(k)=[y(k-G+1)y(k-G+2)...y(k-1)y(k)] T
本发明实施例提供的补偿算法的目的是为了使得补偿后系统的非线性失真量得到抑制甚至消除。对此,本发明实施例从补偿输出s(k)提取出第k个非线性分量值:The purpose of the compensation algorithm provided by the embodiment of the present invention is to suppress or even eliminate the nonlinear distortion of the system after compensation. In this regard, the embodiment of the present invention extracts the kth nonlinear component value from the compensation output s(k):
sf(k,w)=gT×s(k)=gr×[y(k)-B(k)]。 sf (k,w)= gT *s(k)= gr *[y(k)-B(k)].
后续步骤四在进行补偿模型的核向量计算时,应以其非线性分量能量值最小为目标。In the
步骤四、由最小二乘法,对补偿模型的核向量进行迭代计算:
用得到的K个离散数据(非线性分量值)的平方和来表示提取出的非线性信号功率,非线性信号功率(或者说信号能量)可表示为:The extracted nonlinear signal power is represented by the sum of the squares of the obtained K discrete data (nonlinear component values), and the nonlinear signal power (or signal energy) can be expressed as:
其中表示第k个离散输入信号所在的单位时间点数字接收机10的补偿输出的短时能量。以P(w)值最小作为最小二乘法的代价函数,可以得到迭代的公式:in represents the short-term energy of the compensated output of the
w(i)=w(i-1)-{QT[w(i-1)]*Q[w(i-1)]}-1*QT[w(i-1)]*sf[w(i-1)];w(i)=w(i-1)-{Q T [w(i-1)]*Q[w(i-1)]}-1*Q T [w(i-1)]*s f [w(i-1)];
其中,Q(w)是K*N维一阶导数矩阵。迭代公式可进一步表示为:Among them, Q(w) is a K*N-dimensional first-order derivative matrix. The iterative formula can be further expressed as:
其中,/>表示非线性向量中每个元素的累加。 where, /> Represents the accumulation of each element in a nonlinear vector.
由于最小二乘法RLS算法收敛速度快,可以在输入信号实时变化的前提下提高参数辨识能力。可以将代价函数写成:Due to the fast convergence speed of the least squares RLS algorithm, the parameter identification ability can be improved under the premise that the input signal changes in real time. The cost function can be written as:
其中,τ是遗忘因子,0<τ<1,τ与系统非线性失真的变化速度有关。Among them, τ is the forgetting factor, 0<τ<1, τ is related to the change speed of the nonlinear distortion of the system.
求得自相关矩阵R(i)和互相关向量M(i)为:The autocorrelation matrix R(i) and cross-correlation vector M(i) are obtained as:
R(i)=τR(i-1)+V(k)ggTVT(k)R(i)=τR(i-1)+V(k)gg T V T (k)
M(i)=τM(i-1)+gTy(k)V(k)gM(i)=τM(i-1)+g T y(k)V(k)g
推得补偿核向量的更新公式为:The update formula for deriving the compensation kernel vector is:
w(i)=w(i-1)-R-1(i){[V(k)ggTVT(k)]w(i-1)-V(k)ggTy(k))}w(i)=w(i-1)-R -1 (i){[V(k)gg T V T (k)]w(i-1)-V(k)gg T y(k)) }
由于矩阵求逆在一些硬件实现上具有局限性,也可以假设R-1(i)=M(i)来代替计算。Since matrix inversion has limitations in some hardware implementations, R −1 (i)=M(i) can also be assumed to replace the calculation.
最后将更新后的补偿核向量的核系数载入补偿模型,完成非线性失真量相消,具体消除原理如图5所示。Finally, load the kernel coefficient of the updated compensation kernel vector into the compensation model to complete the cancellation of nonlinear distortion. The specific elimination principle is shown in Figure 5.
因此,本发明实施例的优点在于:能够通过识别非线性失真的频率分布,构造滤波器提取出非线性失真分量,构造出补偿信号中非线性能量代价函数并以此辨识补偿模型参数,该方法无需增加额外ADC来获取实际输入信号的情况下,仍能大量消除系统得非线性失真,而能够较好的改善系统无杂散动态范围SFDR性能。Therefore, the advantages of the embodiment of the present invention are: by identifying the frequency distribution of the nonlinear distortion, constructing a filter to extract the nonlinear distortion component, constructing the nonlinear energy cost function in the compensation signal, and using this to identify the compensation model parameters, the method Without adding an additional ADC to obtain the actual input signal, the nonlinear distortion of the system can still be largely eliminated, and the spurious-free dynamic range SFDR performance of the system can be better improved.
本发明针对宽带数字接收机10中存在非线性失真而影响系统无杂散动态范围SFDR的问题提出了一种基于最小二乘法的后补偿模型构建方法,该方法无需添加额外ADC采集参考信号,可以削弱信号的非线性失真分量,降低信号的归一化均方误差NMSE,提升系统的无杂散动态接收范围。The present invention proposes a method for constructing a post-compensation model based on the least squares method for the problem that non-linear distortion exists in the wideband
如图6所示,为方便阐述,本发明实施例以双音信号做仿真实验验证上述后补偿模型对非线性失真消除的可靠性,具体步骤如下:As shown in Figure 6, for the convenience of explanation, the embodiment of the present invention uses a dual-tone signal as a simulation experiment to verify the reliability of the above-mentioned post-compensation model for nonlinear distortion elimination, and the specific steps are as follows:
步骤1、选择合适的非线性模型来模拟射频前端13与ADC的非线性失真,载入测试信号,得到失真信号。产生输入数据x(k):
其中fs是采样频率,设为100MHZ。f1、f2为双音信号频率,这里分别设为6.3MHZ、10.3MHZ。取Volterra级数第2、3阶项的最大记忆深度为2,构造的非线性级数模型为:Where fs is the sampling frequency, set to 100MHZ. f 1 and f 2 are the frequencies of the two-tone signals, which are respectively set to 6.3MHZ and 10.3MHZ here. Taking the maximum memory depth of the second and third order items of the Volterra series as 2, the constructed nonlinear series model is:
y(k)=Y(k)*Wy(k)=Y(k)*W
Y(k)=[x(k),x2(k),x(k)x(k-1),x2(k-1),x3(k),x2(k)x(k-1),x(k)x2(k-1),x3(k-1)],W=10-2×[100,0.028,1.232,0.667,0.923,1.188,1.383,1.107]。Y(k)=[x(k), x 2 (k), x(k)x(k-1), x 2 (k-1), x 3 (k), x 2 (k)x(k -1), x(k) x 2 (k-1), x 3 (k-1)], W = 10 -2 × [100, 0.028, 1.232, 0.667, 0.923, 1.188, 1.383, 1.107].
W为非线性级数模型的核向量,将x(k)代入模型,得到接收机的失真输出信号y(k)。W is the kernel vector of the nonlinear series model, and x(k) is substituted into the model to obtain the distorted output signal y(k) of the receiver.
步骤2、绘制功率密度图,设置阈值,辨识强信号与失真信号。对于宽带接收机整个接收频段而言,接收到的强信号通常分布的较为稀疏,而接收机系统的非线性失真分量可以认为主要由强信号带来。对信号求N点离散傅里叶变换,求取信号的功率谱密度,绘制功率谱密度图如图7所示。
从图7中可以看出,信号失真后产生了多个失真分量,这些量的功率值较大。系统的最大无杂散功率谱范围SFDR只有31dB。It can be seen from Fig. 7 that multiple distortion components are generated after the signal is distorted, and the power values of these quantities are relatively large. The maximum spurious-free power spectrum range SFDR of the system is only 31dB.
步骤3、由功率谱图可以大致估测出失真信号的频率分布位置,由非线性失真的频率信息,构造多通带滤波器,并导出滤波器系数。将FIR抽头系数向量定义为g=[g0g1…gG-1]T,维数为G*1。这里将滤波器的系数长度设置为150。
步骤4、由最小二乘法,对补偿模型的核向量进行迭代计算。整个自适应参数更新过程如图8所示。
构造自相关矩阵R(i):R(i)=τR(i-1)+V(k)ggTVT(k)。Construct the autocorrelation matrix R(i): R(i)=τR(i-1)+V(k)gg T V T (k).
利用最小二乘法RLS算法更新补偿模型参数,训练次数设置为200次。The parameters of the compensation model were updated using the least squares RLS algorithm, and the training times were set to 200.
w(i)=w(i-1)-R-1(i){[V(k)ggTVT(k)]w(i-1)-V(k)ggTy(k)}}w(i)=w(i-1)-R -1 (i){[V(k)gg T V T (k)]w(i-1)-V(k)gg T y(k)} }
最后将计算出的系数更新到补偿模型B(k)中:B(k)=AT(k)×w,其中:Finally, update the calculated coefficients to the compensation model B(k): B(k)= AT (k)×w, where:
A(k)=[v(k-G+1)v(k-G+2)…v(k-1)v(k)]。A(k)=[v(k-G+1)v(k-G+2)...v(k-1)v(k)].
v(k)=[y2(k)y(k)y(k-1)…y2(k-Nd+1)y3(k)y2(k)y(k-1)…yD(k-Nd+1)]T。v(k)=[y 2 (k)y(k)y(k-1)...y 2 (kN d +1)y 3 (k)y 2 (k)y(k-1)...y D ( kN d +1)] T .
补偿后信号的频谱图如图9所示。The spectrum diagram of the compensated signal is shown in Fig. 9 .
从图9中可以发现,非线性失真量已经得到很好的抑制,通过本方法进行补偿后,系统的SFDR值已经由原来的32dB提升到53dB,有了22dB的改善。另外,采用归一化均方误差NMSE来对该方案线性化效果进行衡量。其数学表达式为:It can be seen from Figure 9 that the amount of nonlinear distortion has been well suppressed. After compensation by this method, the SFDR value of the system has been increased from the original 32dB to 53dB, which is an improvement of 22dB. In addition, the normalized mean square error (NMSE) is used to measure the linearization effect of the scheme. Its mathematical expression is:
其中,yr(i)为实际输入数据,作为标准的参考信号,ys(i)为本方案补偿后输出的补偿信号,K为参与计算的输出数据个数。NMSE比较的是补偿输入信号与实际信号的偏差,所以该值越小越好。通过计算,补偿前系统的NMSE是负20dB,补偿后系统的NMSE大幅下降,为负40dB。说明通过本发明后信号接收的质量有了大幅提升,改善了脉冲场源输出信号的非线性失真。Among them, y r (i) is the actual input data as a standard reference signal, y s (i) is the compensation signal output after compensation in this scheme, and K is the number of output data involved in the calculation. What NMSE compares is to compensate the deviation between the input signal and the actual signal, so the smaller the value, the better. By calculation, the NMSE of the system before compensation is negative 20dB, and the NMSE of the system after compensation drops significantly to negative 40dB. It shows that the quality of signal reception has been greatly improved by the invention, and the nonlinear distortion of the pulse field source output signal has been improved.
为了便于描述,在这里可以使用空间相对术语,如“在……之上”、“在……上方”、“在……上表面”、“上面的”等,用来描述如在图中所示的一个器件或特征与其他器件或特征的空间位置关系。应当理解的是,空间相对术语旨在包含除了器件在图中所描述的方位之外的在使用或操作中的不同方位。例如,如果附图中的器件被倒置,则描述为“在其他器件或构造上方”或“在其他器件或构造之上”的器件之后将被定位为“在其他器件或构造下方”或“在其他器件或构造之下”。因而,示例性术语“在……上方”可以包括“在……上方”和“在……下方”两种方位。该器件也可以其他不同方式定位(旋转90度或处于其他方位),并且对这里所使用的空间相对描述作出相应解释。For the convenience of description, spatially relative terms may be used here, such as "on ...", "over ...", "on the surface of ...", "above", etc., to describe The spatial positional relationship between one device or feature shown and other devices or features. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, devices described as "above" or "above" other devices or configurations would then be oriented "beneath" or "above" the other devices or configurations. under other devices or configurations". Thus, the exemplary term "above" can encompass both an orientation of "above" and "beneath". The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.
此外,需要说明的是,使用“第一”、“第二”等词语来限定零部件,仅仅是为了便于对相应零部件进行区别,如没有另行声明,上述词语并没有特殊含义,因此不能理解为对本申请保护范围的限制。In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing corresponding components. To limit the protection scope of this application.
以上所述仅为本申请的优选实施例而已,并不用于限制本申请,对于本领域的技术人员来说,本申请可以有各种更改和变化。凡在本申请的精神和原则之内,所作的任何修改、等同替换、改进等,均应包含在本申请的保护范围之内。The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.
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