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公开(公告)号：EP0795986A3
公开(公告)日：2000-11-22
申请号：EP97301456.6
申请日：1997-03-04
CPC分类号： H04L27/30
摘要： An adaptive Infinite Impulse Response (IIR) filter is provided that can adaptively detect the presence of one or more tones in its input stream. The tones to be detected may be of arbitrary frequency, subject only to a limitation that such tones fall within a frequency band consistent with accepted sampling principles ( e.g. , a maximum frequency of interest no greater than one-half the sampling frequency -- Nyquist sampling criteria). An IIR filter developed according to the method of the invention will adaptively locate the frequencies of tones to be detected, thereby allowing for frequency drift from nominal expected frequency values with no loss in accuracy. Such a filter will also process the input signal sample-by-sample, thereby avoiding the blocking problem of FFT-based filter approaches. With the filter of the invention, an application can identify the frequencies, associated power levels, SNR and duration of the tones. Thus, such an application can use a simple user specified library of tone parameters to decide if tones of interest are present in the input stream.
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公开(公告)号：EP0795986A2
公开(公告)日：1997-09-17
申请号：EP97301456.6
申请日：1997-03-04
IPC分类号： H04L27/30
CPC分类号： H04L27/30
摘要： An adaptive Infinite Impulse Response (IIR) filter is provided that can adaptively detect the presence of one or more tones in its input stream. The tones to be detected may be of arbitrary frequency, subject only to a limitation that such tones fall within a frequency band consistent with accepted sampling principles ( e.g. , a maximum frequency of interest no greater than one-half the sampling frequency -- Nyquist sampling criteria). An IIR filter developed according to the method of the invention will adaptively locate the frequencies of tones to be detected, thereby allowing for frequency drift from nominal expected frequency values with no loss in accuracy. Such a filter will also process the input signal sample-by-sample, thereby avoiding the blocking problem of FFT-based filter approaches. With the filter of the invention, an application can identify the frequencies, associated power levels, SNR and duration of the tones. Thus, such an application can use a simple user specified library of tone parameters to decide if tones of interest are present in the input stream.
摘要翻译： 提供了一种自适应无限脉冲响应（IIR）滤波器，可以自适应地检测其输入流中一个或多个音调的存在。 要检测的音调可以是任意频率，仅受限于这样的音调落入与接受的采样原理一致的频带内（例如，不大于采样频率的一半的奈奎斯特采样 标准）。 根据本发明的方法开发的IIR滤波器将自适应地定位待检测的音调的频率，从而允许来自标称预期频率值的频率漂移，而不会损失精度。 这样的滤波器也将逐个处理输入信号，从而避免基于FFT的滤波器方法的阻塞问题。 利用本发明的滤波器，应用可以识别频率，相关联的功率电平，SNR和音调的持续时间。 因此，这样的应用可以使用简单的用户指定的音调参数库来决定感兴趣的音调是否存在于输入流中。
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