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1. 发明授权

US4245345A Timing acquisition in voiceband data sets 失效
标题翻译：语音带数据集中的时序采集
公开(公告)号：US4245345A
公开(公告)日：1981-01-13
申请号：US75646
申请日：1979-09-14
申请人： Richard D. Gitlin , Edmond Y. Ho , Howard C. Meadors, Jr. , Stephen B. Weinstein
发明人： Richard D. Gitlin , Edmond Y. Ho , Howard C. Meadors, Jr. , Stephen B. Weinstein
IPC分类号： H03H15/00 , H04B3/04 , H04L7/00 , H04L7/02 , H04L7/04 , H04L7/10 , H04L27/01
CPC分类号： H04L7/10 , H04L27/01 , H04L7/007 , H04L7/046
摘要： In a multipoint data communication system using quadrature-amplitude modulation, a master modem (20) and a plurality of tributary modems (11a, 11b . . . 11n) are interconnected via respective transmission channels (13a, 13b . . . 13n, 16). Adaptive equalizer circuitry (55, 56) in the master modem equalizes the channel from a particular tributary by multiplying samples of signals received from the tributary by an ensemble of tap coefficients associated with the tributary. The tap coefficient ensembles for each tributary are stored in a memory (91) from which they are retrieved at the start of transmission from that tributary. Timing-acquisition circuitry (29) within the master modem adjusts the phase of the latter's sampling circuitry (23, 27) at the start of transmission from a given tributary so that the received signals are sampled at the correct time points. In particular, a timing acquisition signal having spectral components only within the non-rolloff region of the equalized baseband-equivalent transfer function is transmitted by the tributary. The master samples and equalizes the received timing acquisition signal to form a succession of timing acquisiton equalizer outputs. The time by which the operation of the sampling circuitry is to be advanced or retarded is determined as a trigonometric function of two successive ones of the timing acquisition equalizer outputs. The timing acquisition signal is illustratively a double-dotting pattern having a four-symbol-interval period. That period is integrally related to the carrier frequency. This allows the samples needed in order to begin forming the timing acquisition equalizer outputs to be generated by replicating the samples taken over only four symbol intervals.
摘要翻译：在使用正交幅度调制的多点数据通信系统中，主调制解调器（20）和多个支路调制解调器（11a，11b，...，11n）经由各个传输信道（13a，13b，...，13n，16）互连，。主调制解调器中的自适应均衡器电路（55,56）通过将从支路接收的信号的采样乘以与支路相关联的抽头系数的整体来均衡来自特定支路的信道。每个支流的抽头系数集合存储在从该支流的传输开始时从其中检索它们的存储器（91）中。主调制解调器内的定时采集电路（29）在给定支路的发送开始时调整后者的采样电路（23,27）的相位，使得接收的信号在正确的时间点进行采样。特别地，仅在均衡的基带等效传递函数的非滚降区域内具有频谱分量的定时获取信号由支流传输。主机采样并均衡接收到的定时采集信号，形成一系列定时采集均衡器输出。将采样电路的操作提前或延迟的时间确定为两个连续的定时获取均衡器输出的三角函数。定时获取信号示例性地是具有四符号间隔周期的双点图案。这个时期与载波频率是一体的。这允许为了开始形成定时获取均衡器输出而需要的样本，通过复制仅在四个符号间隔所取的样本来产生。

2. 发明授权

US4237554A Coefficient tap leakage for fractionally-spaced equalizers 失效
$Coefficient tap leakage for fractionally-spaced equalizers$
标题翻译：分数间隔均衡器的抽头泄漏系数
公开(公告)号：US4237554A
公开(公告)日：1980-12-02
申请号：US016495
申请日：1979-03-01
申请人： Richard D. Gitlin , Howard C. Meadors, Jr. , Stephen B. Weinstein
发明人： Richard D. Gitlin , Howard C. Meadors, Jr. , Stephen B. Weinstein
IPC分类号： H03H15/00 , H03H21/00 , H04B3/06 , H04L25/03 , H04L25/04 , H04L27/01 , H04B3/04
CPC分类号： H04L27/01
摘要： A quadrature amplitude modulated (QAM) data signal transmitted at T symbols per second is sampled in a data receiver at a rate of 2/T samples per second and applied to a transversal-type equalizer structure (25, 46, 34, 35) having taps spaced at T/2 second intervals. A demodulated equalized signal (a.sub.j, b.sub.j), generated once every T seconds, is quantized to form a decision (a.sub.j *, b.sub.j *) as to the value of the original modulating data symbol. An error signal (e.sub.j, e.sub.j) is formed in response to the pre- and post-quantized values of the demodulated equalized signal. Tap coefficients (c.sub.i (j), c.sub.i (j)) used in generating the equalized signals are updated in response to (a) a correction term which is a function of the error signal and (b) a predetermined tap leakage term which has a constant magnitude. The introduction of the tap leakage term maintains the coefficient values at minimum levels.
摘要翻译：以每秒T个符号发送的正交幅度调制（QAM）数据信号以每秒2个/ T个采样的速率在数据接收机中采样，并被施加到横向型均衡器结构（25,46,34,35），其具有水龙头以T / 2秒间隔隔开。将每T秒一次产生的解调均衡信号（aj，bj）量化，以形成关于原始调制数据符号的值的判定（aj *，bj *）。响应于解调的均衡信号的前后量化值形成误差信号（ej，ej）。响应于（a）作为误差信号的函数的校正项和（b）预定的抽头泄漏项，更新用于产生均衡信号的抽头系数（ci（j），ci（j）），其具有恒定幅度。抽头泄漏项的引入将系数值保持在最低水平。

3. 发明授权

US4334313A Timing recovery technique 失效
标题翻译：定时恢复技术
公开(公告)号：US4334313A
公开(公告)日：1982-06-08
申请号：US185016
申请日：1980-09-08
申请人： Richard D. Gitlin , Howard C. Meadors, Jr.
发明人： Richard D. Gitlin , Howard C. Meadors, Jr.
IPC分类号： H04L7/02 , H04B3/04
CPC分类号： H04L7/0058
摘要： In a first data receiver (10), sampling circuitry (20, 25, 35) forms samples of a received data signal representing a succession of data symbols. The samples are formed at twice the symbol rate. Transversal filter circuitry (251, 261) operates on the samples by multiplying them by respective ones of a queue of coefficients. Further circuitry (55, 60, 65, 70, 252, 262), operative in response to the resulting products, forms decisions as to the values of the transmitted symbols and updates the values of the coefficients. Timing recovery circuitry (40) periodically identifies the largest of the coefficients in magnitude and either advances or retards the operation of the sampling circuitry by a fixed step size depending on whether that coefficient is or is not within a predetermined portion of the queue. Timing recovery circuitry (830) within a second data receiver (100) operates in a similar manner, but employs a step size whose magnitude is determined by the position of the largest coefficient relative to the center of the coefficient queue.
摘要翻译：在第一数据接收器（10）中，采样电路（20,25,35）形成表示一系列数据符号的接收数据信号的采样。样品以符号率的两倍形成。横向滤波器电路（251,261）通过将它们乘以系数队列中的相应的一个来对样本进行操作。响应于所得到的产品可操作的进一步的电路（55,60,65,70,252,262）形成关于发送符号的值的决定并更新系数的值。定时恢复电路（40）周期性地识别幅度中最大的系数，并且取决于系数是否在队列的预定部分内或者不在队列的预定部分内，使采样电路的操作前进或延迟固定的步长。第二数据接收器（100）内的定时恢复电路（830）以类似的方式操作，但采用其幅度由相对于系数队列的中心的最大系数的位置确定的步长。

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