共查询到17条相似文献,搜索用时 125 毫秒
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方位多通道技术是合成孔径雷达(SAR)实现高分宽测的手段之一。在多通道系统中通道失配是不可避免的,这会导致SAR 图像模糊。已有的通道失配校正方法大多依赖于系统参数以及场景内容。参数的不确定性将会大大降低校正算法的稳定性。该文提出了一种改进的通道失配校正方法,根据失配产生的原因,将通道失配分为距离增益误差、脉冲采样时钟误差和传输相位误差3 项。前两项误差通过交替估计进行补偿,而传输相位误差则通过代价函数给予估计。该方法对成像场景的依赖较小,基于机载多通道验证平台实测数据的实验验证了该方法的有效性。 相似文献
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多片ADC并行采集系统的误差时域测量与校正 总被引:3,自引:0,他引:3
并行时间交替采样是提高系统最大采样率的有效方法之一,但由于制造工艺的局限性,并行时间交替采样将不可避免地造成通道失配误差。本文利用正弦采样信号的时域特性,推导出一种快速而精确的算法,用于同时校正通道失配引起的增益误差、偏置误差和时间误差,并通过模拟仿真证明了算法的可行性。 相似文献
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为了降低并行时间交替采样系统中通道失配误差的 硬性,利用两个标准斜波 信号的时域特性,对斜波信号多次采样,采样点减去偏置误差得到的无偏置采样值,从而求 解采样点的时间误差和增益误差联立方程,计算时间和增益误差。本文算法的采样点数和推导计算量较少,是一种快速而 精确的工程实用算法;并使用Matlab对本文算法进行模拟仿真证明其可行性,并通过Farrow 结构的滤波器对估计所得的通道失配误差进行校正验证,校正后的无杂散动态范围(SFDR,spurious free dynamic range)至少达到50dB。 相似文献
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针对接收阵列射频通道间增益不一致以及系统感知模型与目标角度信息失配等情况下,基于压缩感知(Compressive Sensing,CS)的多目标波达方向(Direction of Arrival,DOA)估计方法性能下降的问题,提出了一种新的单通道CS-DOA估计方法.引入一种单通道阵列体制,并建立系统模型失配时的DOA稀疏感知模型;将丹茨格(Dantzig Selector,DS)算法和遗传算法相结合,分别对目标角度信息矢量和系统模型失配误差进行交替迭代优化.该方法有效克服了常见CS-DOA方法无法抑制系统模型失配误差的问题,避免了射频通道间增益不一致对DOA估计性能的影响.仿真结果表明:该方法性能优于传统DOA估计算法,能够对任意相关性信号进行有效DOA估计,具有更高的角度分辨力和估计精度. 相似文献
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在高速OFDM接收机中利用分时ADC(TIADC)对接收信号进行采样,解决了单片ADC不能满足传输速率高达数Gb/s的通信系统需求的难题。由于TIADC各通道间的不匹配,时钟失配误差和增益失配误差大大影响了系统性能。在传输速率为4 Gb/s的OFDM系统中,利用4通道TIADC对接收信号进行采样,对两种失配误差和信道进行联合估计与均衡,并针对64QAM符号调制,对TIADC进行采样精度仿真。仿真结果证明,校准后的9位TIADC可以使系统误码率接近理想值。 相似文献
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该文提出一种改进的时间交错采样模数转换器(TIADC)失配误差补偿方法。系统通过误差参数和简化的拉格朗日插值算法分别实现了对偏置、增益的失配误差补偿和采样时间的失配误差补偿。该补偿方法在FPGA中采用低复杂度的定点运算实现,在TIADC硬件平台中实现了对多通道ADC采样数据的线上校正。实验结果表明:所提改进方法在仿真环境下使无杂散动态范围提升了51 dB,并且在硬件实现过程中使SFDR优化达45 dB。在保持失配误差估计精度和补偿效果优良的前提下,该方法不仅降低了算法的计算复杂度,而且该补偿结构不受TIADC通道数目的限制。 相似文献
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时间交叉模数转换结构是提高模数转换系统采样率的一种有效途径。由于制造工艺的局限和布线的差异,这种结构会引入通道失配而限制系统的性能。通道失配包括偏置失配、增益失配和时间失配。文中提出了一种基于快速傅里叶变换(Fast Fourier Transform,FFT)计算时间失配并采用有限冲激响应(Finite Impusle Response,FIR)滤波器对它进行补偿的方法,并通过Matlab仿真验证了算法的有效性和可行性。 相似文献
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为了提高时间交织模数转换器(TIADC)的有效分辨率,需要对其通道之间的线性/非线性失配误差进行估计和补偿。该文针对M通道TIADC的带有记忆效应的非线性失配误差提出了一种自适应盲校正算法。通过子通道重构结构(SCR)重构非线性误差信号,并通过滤波降采样最小均方(FDLMS)算法估计非线性失配误差系数。实验仿真结果表明,该方法可以有效校正带有记忆效应的非线性失配误差,并且可以大大降低实现难度和硬件资源消耗。 相似文献
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本文介绍了作者对200MHz并行多通道实时采样系统中固有的误差:多通道非均匀时间采样误差和增益误差校正的方法。在频域对采样数据进行频谱重建,消除了由于非均匀时间采样引入的高次谐波,使得采样时间误差均值减小到原来的3.84。同时还对增益误差进行了完全校正,取得了较好的效果。 相似文献
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In data acquisition systems, with help of time-interleaved analog-to-digital converter (TIADC) architecture, the maximum sample rate of the whole system can be increased efficiently. However, inevitable offset mismatch, gain mismatch, and timing error between time-interleaved channels degrade the sampling performance. In order to develop the mismatched TIADC structure, this paper first proposes a new time-domain algorithm to estimate the three aforementioned mismatch errors, and then puts forward a calibration method to calibrate the mismatch errors. Finally, numerical simulations are presented to verify the proposed estimation and calibration algorithm. 相似文献
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It is well known that an OFDM receiver is vulnerable to synchronization errors. Despite fine estimations used in the initial acquisition, there are still residual synchronization errors. Though these errors are very small, they severely degrade the bit error rate (BER) performance. In this paper, we propose a residual error elimination scheme for the digital OFDM baseband receiver aiming to improve the overall BER performance. Three improvements on existing schemes are made: a pilot‐aided recursive algorithm for joint estimation of the residual carrier frequency and sampling time offsets; a delay‐based timing error correction technique, which smoothly adjusts the incoming data stream without resampling disturbance; and a decision‐directed channel gain update algorithm based on recursive least‐squares criterion, which offers faster convergence and smaller error than the least‐mean‐squares algorithms. Simulation results show that the proposed scheme works well in the multipath channel, and its performance is close to that of an OFDM system with perfect synchronization parameters. 相似文献
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Elbornsson J. Gustafsson F. Eklund J.-E. 《Signal Processing, IEEE Transactions on》2005,53(4):1413-1424
To significantly increase the sampling rate of an analog-to-digital converter (ADC), a time-interleaved ADC system is a good option. The drawback of a time-interleaved ADC system is that the ADCs are not exactly identical due to errors in the manufacturing process. This means that time, gain, and offset mismatch errors are introduced in the ADC system. These errors cause distortion in the sampled signal. In this paper, we present a method for estimation and compensation of the time mismatch errors. The estimation method requires no knowledge about the input signal, except that it should be band limited to the foldover frequency /spl pi//T/sub s/ for the complete ADC system. This means that the errors can be estimated while the ADC is running. The method is also adaptive to slow changes in the time errors. The Cramer-Rao bound (CRB) for the time error estimates is also calculated and compared to Monte Carlo simulations. The estimation method has also been validated on measurements from a real time-interleaved ADC system with 16 ADCs. 相似文献
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Wenchang Sun Xingwei Zhou 《Signal Processing, IEEE Transactions on》2000,48(1):223-226
The error estimate is useful in the application of the sampling theorem. For the classical Shannon sampling theorem, various errors are widely studied, but for the sampling theorem in general wavelet subspaces, only the aliasing error is studied. In this paper, we study three other errors: truncation error, amplitude error, and time-jitter error. With the same technique, a result on irregular sampling is improved 相似文献