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US4674103A Method and arrangement for detecting the presence of a training signal in a modem receiver 失效
用于检测调制解调器接收机中训练信号的存在的方法和装置

Method and arrangement for detecting the presence of a training signal in a modem receiver
摘要：
For rapidly detecting a periodic training signal in a modem receiver, delay line storage (21) is provided for a signal section which is equal to one training signal period (q.multidot.M samples) plus an additional adjacent window (q.multidot.W samples). Thus, the stored signal section includes two windows (17', 19) which are offset by one training signal period and which are similar if a training signal is present. In evaluation means (41) connected to the two windows (17', 19), two auxiliary signals (z.sub.1, z.sub.2) are generated (61, 65) which represent the signal energy and the correlation, respectively, of the samples in the two windows. From the auxiliary signals, a dissimilarity metric (z.sub.3) is derived (69) and is compared (73) to a given threshold for generating an indicator signal (CYC) which becomes active when a training signal is present, i.e. when the two window contents are similar and the metric (z.sub.3) falls below the threshold. A carrier frequency offset estimate (.DELTA..sub.f) is also derived from the second auxiliary signal (z.sub.2).
摘要（中）：

为了快速检测调制解调器接收机中的周期性训练信号，为等于一个训练信号周期（q×M个样本）加上附加的相邻窗口（q×W个样本）的信号部分提供延迟线存储器（21）。 因此，存储的信号部分包括被一个训练信号周期偏移的两个窗口（17'，19），并且如果存在训练信号则这两个相似。 在连接到两个窗口（17'，19）的评估装置（41）中，生成两个辅助信号（z1，z2），分别表示两个样本中的信号能量和相关性 视窗。 从辅助信号中，导出不同度量（z3）（69）并与（73）比较（73）给定阈值，以产生当存在训练信号时变为有效的指示信号（CYC），即当两个窗口内容 是相似的，度量（z3）低于阈值。 还从第二辅助信号（z2）导出载波频率偏移估计（DELTA f）。

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