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公开(公告)号：US06873650B1
公开(公告)日：2005-03-29
申请号：US09607619
申请日：2000-06-30
CPC分类号： H04L27/2608
摘要： A circuit compensating for the difference in transmission rate of digital samples generated in transmit and receive paths between a user and a transceiver processing in the frequency domain, such as a digital multi-tone (DMT) transceiver. Compensation of the DMT transmission rate in the receive path in accordance with exemplary embodiments of the present employs zero-padding of the frequency domain coefficients generated by the DMT transceiver prior to applying an inverse transform, such as the inverse fast Fourier transform (IFFT). Zero-padding the frequency domain coefficients allows for the compensation of the transmission rate in the receive path by generating digital samples from the frequency domain coefficients with an inverse transform having a rate matched to the frequency domain transform and rate employed in the transmit path.
摘要翻译： 补偿在用户与频域中的收发器处理（例如数字多音调（DMT）收发器）之间的发送和接收路径中产生的数字样本的传输速率差异的电路。 根据本发明的示例性实施例，在接收路径中的DMT传输速率的补偿在应用诸如快速傅里叶逆变换（IFFT）的逆变换之前，由DMT收发器产生的频域系数的零填充。 对频域系数进行零填充允许通过利用与发送路径中采用的频域变换和速率匹配的速率的逆变换从频域系数生成数字样本来补偿接收路径中的传输速率。
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公开(公告)号：US07003027B2
公开(公告)日：2006-02-21
申请号：US10016438
申请日：2001-12-10
申请人： Yhean-Sen Lai , Kannan Rajamani
发明人： Yhean-Sen Lai , Kannan Rajamani
CPC分类号： H04B3/23 , H04L25/4927
摘要： Apparatus and devices used to achieve a computationally efficient modem having a transmit path and a receive path. The apparatuses include a Farrow phase shifter for shifting the phase of signals in the transmit path, a fractionally spaced equalizer capable of equalization and signal decimation in the receive path, a primary echo sub-canceler and a post equalizer echo canceler for canceling echoes on the receive path, and a phase locked loop and add/delete register for controlling the sampling rate of a CODEC. The method includes shifting the phase of a transmit signal using a Farrow structure, equalizing and decimating a receive signal with a fractionally spaced equalizer, canceling primary echoes on the receive signal using a sub-canceler structure and canceling remaining echoes using a post equalizer echo canceler, and adjusting the sampling rate of a CODEC using a phase locked loop and an add/delete register.
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3.发明授权Methods and apparatus for providing sample rate conversion between CD and DAT 有权在CD和DAT之间提供采样率转换的方法和设备公开(公告)号：US06772022B1
公开(公告)日：2004-08-03
申请号：US09335277
申请日：1999-06-17
IPC分类号： G06F1700
CPC分类号： G10L19/022
摘要： A method of converting between a sampling rate associated with a first audio format and a second audio format includes up-sampling an input signal sampled at the sample rate associated with the first audio format. Then, the up-sampled signal is filtered as a function of a fractional delay to generate an output signal sampled at the sample rate associated with the second audio format. The fractional delay is computed from the sample rates associated with the first and second audio formats. In one embodiment, the sample rates that are converted between are associated with a compact disc format having a sample rate of about 44.1 kHz and a digital audio tape format having a sample rate of about 48 kHz. In such case, the input samples are preferably up-sampled by a factor of two and the samples are then preferably filtered in accordance with a third order six taps coefficient finite impulse response filtering technique. The methodology of the present invention permits sample rate conversion from the CD format to the DAT format and from the DAT format to the CD format without changing filter coefficients.
摘要翻译： 在与第一音频格式相关联的采样率和第二音频格式之间转换的方法包括对与第一音频格式相关联的采样率采样的输入信号进行上采样。 然后，上采样信号作为分数延迟的函数进行滤波，以产生以与第二音频格式相关联的采样率采样的输出信号。 从与第一和第二音频格式相关联的采样率计算分数延迟。 在一个实施例中，在其之间转换的采样率与具有约44.1kHz的采样率的压缩光盘格式和具有约48kHz的采样率的数字音频磁带格式相关联。 在这种情况下，输入采样优选地以2倍上采样，然后优选地根据三阶六抽头系数有限脉冲响应滤波技术对采样进行滤波。 本发明的方法允许从CD格式到DAT格式和从DAT格式到CD格式的采样率转换，而不改变滤波器系数。
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公开(公告)号：US06721287B1
公开(公告)日：2004-04-13
申请号：US09392380
申请日：1999-09-09
申请人： Yhean-Sen Lai , Kannan Rajamani
发明人： Yhean-Sen Lai , Kannan Rajamani
IPC分类号： H04B320
CPC分类号： H04B3/23 , H04B14/048
摘要： A pulse code modulation modem having a far echo canceller that compensates for robbed bit echo noise by polling the receiving modem for robbed bit position information and incorporating that information into its far echo cancellation circuitry.
摘要翻译： 一种具有远回波消除器的脉码调制调制解调器，其通过轮询接收调制解调器用于抢占比特位置信息并将该信息并入其远回波消除电路来补偿抢地址回波噪声。
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公开(公告)号：US06526429B1
公开(公告)日：2003-02-25
申请号：US09549753
申请日：2000-04-14
申请人： Yhean-Sen Lai , Kannan Rajamani
发明人： Yhean-Sen Lai , Kannan Rajamani
IPC分类号： G06F1710
CPC分类号： G06F17/142 , G06F17/10 , H03H17/08
摘要： A method for designing an all pass filter, in accordance with the present invention, includes providing a plurality of signals having a group delay, and normalizing the group delay to determine a normalized group delay function. Cepstral coefficients of the normalized group delay function are determined for to a denominator polynomial of a transfer function of the all pass filter wherein a magnitude function and the normalized group delay function of the denominator polynomial are related through the cepstral coefficients. The denominator polynomial coefficients are determined through a non-linear recursive difference equation by employing the cepstral coefficients.
摘要翻译： 根据本发明的用于设计全通滤波器的方法包括提供具有群延迟的多个信号，以及归一化群延迟以确定归一化群延迟函数。 归一化组延迟函数的倒谱系数被确定为全通滤波器的传递函数的分母多项式，其中分母多项式的幅度函数和归一化组延迟函数通过倒谱系数相关。 通过使用倒谱系数通过非线性递归差分方程确定分母多项式系数。
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公开(公告)号：US07003100B2
公开(公告)日：2006-02-21
申请号：US10016549
申请日：2001-12-10
申请人： Yhean-Sen Lai , Kannan Rajamani
发明人： Yhean-Sen Lai , Kannan Rajamani
CPC分类号： H04B3/23 , H04L27/2601
摘要： A modem incorporating apparatus and methods to achieve computationally efficient echo cancellation. The apparatus include a cyclic echo synthesizer sub-canceler in the time domain and a echo canceler in the frequency domain. The method includes generating a cyclic echo synthesizer signal using a sub-canceler structure, adding the cyclic echo synthesizer signal to a receive signal in the time domain, generating an echo cancellation signal, and subtracting the echo cancellation signal from the receive signal in the frequency domain. The apparatus and methods may be used for echo cancellation in an asynchronous digital subscriber line (ADSL) modem using discrete multi-tone (DMT) technology.
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公开(公告)号：US06240128B1
公开(公告)日：2001-05-29
申请号：US09096425
申请日：1998-06-11
申请人： Raja Banerjea , Bahman Barazesh , Yhean-Sen Lai , Kannan Rajamani
发明人： Raja Banerjea , Bahman Barazesh , Yhean-Sen Lai , Kannan Rajamani
IPC分类号： H04L516
摘要： A so-called post equalization echo canceler is utilized in conjunction with transmitter and receiver data timing synchronization to enhance tracking of the echo path impulse response and convergence of the transversal filter in the post equalization echo canceler. This is realized by employing the equalization error in the receiver to adapt coefficients of the post equalization echo canceler transversal filter, in conjunction, with the transmitter and receiver data timing synchronization. The timing synchronization is realized by using sample rate conversion of the transmit sample rate to the receive sample rate and, in one example, variable phase interpolation of the converted timing signal. The receiver timing is recovered, and a phase error signal generated by the timing recovery unit is advantageously employed to adjust a variable phase interpolator in the receiver and a variable phase interpolator in a path supplying the transmitter signal to an input of the post equalization echo canceler. This insures that both the adaptive transversal filter of the post equalization echo canceler and a transversal filter in an equalizer in the receiver are operating on data having the same timing. In this example, the timing is that of the received data signal. In an embodiment of the invention, the post equalization echo canceler is utilized in conjunction with a so-called conventional, e.g., a primary, echo canceler. The conventional echo canceler is employed before the equalizer to cancel a major portion of any echo signal, while the post equalization echo canceler is employed after the equalizer to cancel residual echo signals caused primarily by drift in the hybrid network. To this end, the conventional echo canceler is “trained” during the initial half-duplex operation of the modem and, then, updating of its impulse response is inhibited, while the post equalization echo canceler is allowed to continue adapting.
摘要翻译： 所谓后置均衡回波消除器与发射机和接收机数据定时同步结合使用，以增强跟踪均衡回波消除器中的回波路径脉冲响应和横向滤波器的收敛。 这通过在接收机中采用均衡误差来实现，以使后均衡回波消除器横向滤波器的系数与发射机和接收机的数据定时同步相结合。 通过使用发送采样率的采样率转换为接收采样率，并且在一个示例中，转换的定时信号的可变相位插值来实现定时同步。 接收器定时被恢复，并且有利地采用由定时恢复单元产生的相位误差信号来调整接收机中的可变相位内插器和将发射机信号提供给后均衡回波消除器的输入的路径中的可变相位内插器 。 这确保后均衡回波消除器的自适应横向滤波器和接收机中的均衡器中的横向滤波器对具有相同定时的数据进行操作。 在该示例中，定时是所接收的数据信号的时序。 在本发明的一个实施例中，后均衡回波消除器与所谓常规的，例如主回波消除器结合使用。 在均衡器之前采用传统的回波消除器来消除任何回波信号的主要部分，而在均衡器之后采用后均衡回波消除器来消除主要由混合网络中的漂移引起的残余回波信号。 为此，传统的回波消除器在调制解调器的初始半双工操作期间被“训练”，然后，抑制其脉冲响应的更新，同时允许后均衡回波消除器继续适配。
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公开(公告)号：US07949723B2
公开(公告)日：2011-05-24
申请号：US10438109
申请日：2003-05-14
IPC分类号： G06F15/16
CPC分类号： H04L67/34 , H04L69/329 , H04M1/24 , H04M1/2535
摘要： A unique real time tuning (RTT) process is employed for obtaining the desired optimum device parameter adjustments. The RTT parameter adjustment process is utilized with IP phone or other device chipsets as desired. In one embodiment, RTT provides a graphical user interface to a digital signal processor (DSP), or the like, on the device chipset allowing for observation, evaluation and control of the device parameters in real time. The real time exchange of the device parameter information between the device and an external workstation, e.g., a personal computer or the like, is provided by a User Datagram Protocol (UDP) that runs on a controller on the device, e.g., an ARM processor or the like. In this example, the unique combination of the RTT, UDP and DSP cooperate advantageously to implement, in accordance with the principles of the invention, the desired observability, and control to designers to tune the device, e.g., IP Phone, in real time to specified hardware, plastics, audio requirements required by existing standards or the like.
摘要翻译： 采用独特的实时调谐（RTT）过程来获得所需的最佳设备参数调整。 RTT参数调整过程根据需要与IP电话或其他设备芯片组一起使用。 在一个实施例中，RTT向设备芯片组上的数字信号处理器（DSP）等提供图形用户界面，允许实时观察，评估和控制设备参数。 在设备和外部工作站（例如个人计算机等）之间的设备参数信息的实时交换由在设备上的控制器上运行的用户数据报协议（UDP）提供，例如ARM处理器 或类似物。 在该示例中，RTT，UDP和DSP的独特组合有利地协调，以根据本发明的原理实现期望的可观察性，并且控制设计人员实时调谐设备，例如IP电话， 指定的硬件，塑料，现有标准要求的音频要求等。
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公开(公告)号：US06771695B1
公开(公告)日：2004-08-03
申请号：US09364411
申请日：1999-07-30
IPC分类号： H04B138
CPC分类号： H04L25/05 , H04L27/2608
摘要： A DMT signal conforming to a first DMT standard (e.g., the full-rate G.dmt standard based on 255 tones) is sampled at a sampling rate for the first DMT standard, filtered to attenuate a subset of the tones of the first DMT standard (e.g., all G.dmt tones above tone #127), and subsampled (e.g., 2:1) to provide a subsampled, filtered signal that can be further processed using components designed to operate under a second, different DMT standard (e.g., the half-rate G.lite standard based on 127 tones). As such, a conventional half-rate G.lite DMT transceiver can be modified (e.g., by changing the downstream sampling rate from 1.104 MHz to 2.208 MHz and adding an appropriate low-pass filter and decimator) for configuration in a full-rate G.dmt DMT system. The filtering and subsampling ensure that a downstream signal (even if it is a full-rate DMT initialization or synchronization signal containing tones above tone #127) can successfully be further processed using conventional half-rate DMT transceiver components, which are less complex and less expensive than those of full-rate DMT transceivers, thereby enabling the use of relatively inexpensive consumer personal equipment (CPE) in existing distributed full-rate DMT telecommunications systems.
摘要翻译： 符合第一DMT标准（例如，基于255个音调的全速率G.dmt标准）的DMT信号以对于第一DMT标准的采样率进行采样，被滤波以衰减第一DMT标准的音调的子集 （例如，音调＃127之上的所有G.dmt音调），并且被二次采样（例如，2:1）以提供可以使用被设计为在第二种不同DMT标准下操作的组件进一步处理的子采样滤波信号（例如， 基于127个音调的半速率G.lite标准）。 因此，传统的半速率G.lite DMT收发器可以被修改（例如，通过将下行采样率从1.104MHz改变到2.208MHz并添加适当的低通滤波器和抽取器）来配置全速率G .dmt DMT系统。 滤波和二次采样确保下行信号（即使是全速率DMT初始化或包含音调＃127以上的音频的同步信号）也可以使用传统的半速率DMT收发器组件进行进一步处理，这些组件不太复杂和较少 比全速率DMT收发器更昂贵，从而能够在现有的分布式全速率DMT电信系统中使用相对便宜的消费者个人设备（CPE）。
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