共查询到20条相似文献,搜索用时 31 毫秒
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《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(10):1056-1060
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针对短波电台入网中对皮抵消的要求,本文提出采用基于LS准则的FTF算法,同时把“稳健估计(RE)”应用于FTF算法中,并设计出一种新的自适应回波抵消器结构,理论分析和计算机模拟结果都表明该回波抵消器具有收敛速度快,稳态误差小,稳定可靠,抗干扰能力强等特点,明显地提高了短波电台入网的性能。 相似文献
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针对线性调频中断连续波(LFMICW)信号的隐身问题,根据LFMICW回波信号中目标信息处理方法,提出利用信号和匹配滤波器的群延迟特性设计LFMICW对消信号.定义了对消误差因子,并分析了信噪比为6dB且该因子不同取值时单目标的对消结果,利用模糊函数分析对消后的目标合成回波和未对消的干扰目标回波信号的模糊特性,并给出了... 相似文献
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An acoustic echo canceller with sub-band noise cancelling that employs a cascade configuration is proposed. The adaptation control adopted to match the occurrence of intermittent speech/echo and continuous room noise using the NLMS algorithm is very effective in echo and noise cancellation. Hardware is implemented and its performance evaluated through experiments. The noise cancellation significantly enhances overall echo-cancellation performance.<> 相似文献
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Friedman V. Khoury J.M. Theobald M. Gopal V.P. 《Solid-State Circuits, IEEE Journal of》1990,25(4):979-986
The architecture of a codec in which the echo cancellation is done in two stages, an analog hybrid to reduce the echo level at the input of the A/D converter and a programmable digital balance filter, is presented. The design problems connected with this architecture, such as the signal-to-noise performance of the A/D converter and the limiting effects of the variation of the analog components on the echo cancellation performance of the device and on the structure of the digital balance filters, are discussed. These results were used in the design of a single-power-supply CMOS device implemented in 1.5-μm technology using ΣΔ modulation techniques for A/D and D/A conversion. Its echo cancellation performance is sufficiently high that only one set of coefficients per national standard is necessary 相似文献
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一种基于DSP的音频实时处理系统 总被引:1,自引:1,他引:0
声学回声消除器一直是视频会议系统不可缺少的组件。将回声消除算法结合噪音消除和静音检测算法等,提出一种改进的实时音频处理系统方法,并在TMS320C6713B上实现,能够有效改善噪音、双工检测、非线性回声等导致自适应滤波器发散的问题。该系统在保证正常双工通话的同时,对非线性回声的抑制有着明显的改善效果。 相似文献
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An approach to the implementation of asynchronous and timing jitter insensitive data echo cancellation is described. This approach introduces a small amount of jitter in the transmitted data signal, or alternatively in the received signal sampling, and uses a simple digital phase-locked loop together with the storage of two sets of echo canceler coefficients. The effect of derived timing jitter on the echo cancellation accuracy is completely eliminated for a loop timed transceiver (as in a digital subscriber loop network termination transceiver), and is easily reduced to negligible levels for a nonloop timed transceiver (as in a digital subscriber loop line card transceiver or a voiceband data modem). In the case of a voiceband data modem, this approach is one method to achieve asynchronous echo cancellation without the need to recover and resample a continuous-time far-end data signal. 相似文献
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A new echo cancellation structure for discrete multitone systems is presented, where each used tone has its own per-tone echo canceller in addition to a per-tone equalizer, which provides an alternative to currently employed time domain and time/frequency domain approaches. The per-tone approach enables us to optimize the signal-to-noise ratio for each tone separately by solving a minimum mean-square error problem for each tone, with implicit so-called joint shortening. Complexity during data transmission is compared for time domain, time/frequency domain, and per-tone echo cancellation. Structures with reduced complexity are derived for an interpolated and a decimated rate setup. Finally, simulation results for an asymmetric digital subscriber line setting demonstrate improved performance over time domain (or time/frequency domain) echo cancellation. 相似文献
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针对通信中的回波问题,基于自适应滤波的LMS算法,设计了自适应回波抵消器。并基于利用FPGA芯片,在DSP Builder平台上,有效结合MatLab/Simulink和Quartus II设计工具,根据模块化设计思想实现了LMS算法自适应回波抵消器硬件电路设计。软件仿真和系统FPGA硬件实测结果表明,该设计方法使回波抵消器的FPGA硬件实现更加简便快捷。 相似文献
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Echo cancellation as an effective technique for echo control on telephone circuits is burdened by the appearance of carrier frequency offsets and phase jitter in some echo paths. In this paper we present a digital phase-adaptive structure for cancellation which will automatically compensate for echo path frequency offsets as large as 0.001 of the sampling rate without any reduction in return/loss enhancement. 相似文献
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自适应旁瓣对消技术能够很好地抑制旁瓣干扰,但在应用中发现, 自适应旁瓣对消对跟踪的高信噪比目标带来的信噪比损失较大,导致单脉冲和差测角精度下降。本文提出了一种基于CLEAN算法的自适应旁瓣对消方法,首先通过观测目标的先验信息构建目标回波模型,再利用该回波模型剔除对消通道中的目标信息,然后基于剔除目标信息后的对消通道数据,重新计算最优加权值进行主通道的干扰对消,最后仿真和实测结果验证了该方法不仅可以减少主通道中目标对消后的信噪比损失,同时也降低了对消后对目标测角精度的影响。 相似文献
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Loudspeaker nonlinearity at high volumes limits the achievable echo cancellation performance in linear acoustic echo cancellers. A new nonlinear adaptive filter for improving the echo cancellation performance at high volumes for hands free telephones is proposed. Experimental measurements show that an echo cancellation improvement of >8 dB can be obtained at high volumes as compared to a linear adaptive filter 相似文献
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提出了一种回声消除和噪声抑制算法,采用改进的自适应步长非线性滤波技术,用单芯片对该算法进行了实现.用180nm 3.3V/1.8V 6层金属混合信号CMOS工艺流片,可达70dB的声学回声消除性能,噪音消除达20dB,侧音消除达30dB.该芯片包含1个16位DSP、3个14位Σ-Δ ADC、2个16位Σ-Δ DAC、 以及内置ROM和RAM等,并集成有USB、UART、I2C和PCM等接口.测试结果表明该芯片具有全双工和远距离免提的功能,支持双路麦克风输入,技术规范符合G.165国际标准.该芯片功耗低,外围电路简单,自适应能力强,可广泛应用于蓝牙车载免提通信、GPS和即时通讯等领域. 相似文献
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基于WCDMA标准提出了FPGA+DPS平台下实现在数字中频技术中抵消WCDMA直放站回波干扰信号的方案.首先发射与WCDMA信号不相关的伪随机序列CAZAC码作为训练序列进行信道初估计,然后将初估计得到的时延和幅度信息作为赋给LMS自适应滤波器的初值,生成逼近干扰信号的抵消信号,实现回波对消.使用MATLAB和SIMULINK联合仿真,证明该方法拥有良好的性能. 相似文献
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根据多发多收合成孔径雷达(MIMO-SAR)的特点,提出在重叠等效相位中心(EPC)处采用对消处理抑制欺骗干扰的方法.MIMO-SAR采用收发同置天线配置可形成多组位置相同的等效相位中心;发射多载频线性调频(LFM)信号将使每组位置重叠等效相位中心处的回波相位有所差异.利用此特点,可以在子回波相位补偿后采用对消处理对欺骗干扰进行抑制.文中给出了收发同置MIMO-SAR的系统模型,分析了欺骗干扰下的回波特点,指出在位置重叠等效相位中心处的欺骗干扰信号对间仅存在相位差异,给出了对消处理完成欺骗干扰抑制的信号流程,实验结果证明了本文方法的有效性. 相似文献