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公开(公告)号：US06725027B1
公开(公告)日：2004-04-20
申请号：US09624009
申请日：2000-07-21
IPC分类号： H04B110
CPC分类号： H04B1/1669 , H04B1/1081
摘要： A multipath noise reducer detects and removes the individual noise spikes occurring in an interval of multipath noise, thereby reducing the multipath noise with minimal distortion of the audio output signal. The multipath noise spikes are detected by comparing a rectified signal with a threshold signal derived from the rectified signal. When the multipath noise reducer is used in an FM stereo radio receiver, stereo separation may also be controlled according to the detection of multipath noise.
摘要翻译： 多径噪声减少器检测并去除在多径噪声间隔中出现的各个噪声尖峰，从而以最小的音频输出信号失真减少多路径噪声。 通过将整流信号与从整流信号导出的阈值信号进行比较来检测多径噪声尖峰。 当FM立体声无线电接收机中使用多路径降噪器时，也可以根据多路径噪声的检测来控制立体声分离。
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公开(公告)号：US06795559B1
公开(公告)日：2004-09-21
申请号：US09723201
申请日：2000-11-28
IPC分类号： H04B1500
CPC分类号： H04B1/1027
摘要： An impulse noise reducer detects impulse noise in an audio signal by detecting and smoothing the high-frequency amplitude of the audio signal, attenuating the non-smoothed amplitude according to the smoothed amplitude, and comparing the attenuated amplitude with a threshold. Impulse noise is discriminated from high-frequency audio components because the latter tend to occur in longer-lasting bursts and are therefore attenuated more strongly. The impulse noise reducer is simplified because it does not have to perform intermediate-frequency signal processing, and its sensitivity is not affected by adjacent-channel signals because these signals are substantially absent from the audio signal. The impulse noise reducer can be implemented by digital signal processing, and is suitable for use in a medium-wave AM audio broadcast receiver.
摘要翻译： 脉冲噪声降低器通过检测和平滑音频信号的高频振幅来检测音频信号中的脉冲噪声，根据平滑的幅度衰减非平滑幅度，并将衰减幅度与阈值进行比较。 脉冲噪声与高频音频分量区分开来，因为后者往往会发生在持续较长的脉冲串中，因此会更强烈地衰减。 由于不需要执行中频信号处理，所以脉冲噪声减少器被简化，并且其灵敏度不受相邻信道信号的影响，因为这些信号基本上不存在于音频信号中。 脉冲减噪器可以通过数字信号处理实现，适用于中波AM音频广播接收机。
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公开(公告)号：US06385261B1
公开(公告)日：2002-05-07
申请号：US09233173
申请日：1999-01-19
IPC分类号： H03D104
CPC分类号： H04B1/10
摘要： An impulse noise detector detects impulse noise in an audio signal by filtering out the audio components of the signal, then comparing an envelope of a filtered signal with a threshold obtained as a moving average of the envelope. Short-duration impulse noise is thereby detected without detecting tone bursts and other fast-rising signals of longer duration. The envelope may be taken directly from the filtered signal, or from a difference signal obtained from a preliminary envelope of the filtered signal, to emphasize impulse noise when distorted audio components leak into the filtered signal.
摘要翻译： 脉冲噪声检测器通过滤除信号的音频分量来检测音频信号中的脉冲噪声，然后将滤波信号的包络与作为包络的移动平均值获得的阈值进行比较。 从而在没有检测到较长持续时间的音调脉冲串和其它快速上升信号的情况下检测短时脉冲噪声。 可以从经滤波的信号或从滤波信号的初始包络获得的差分信号直接取包络线，以便在失真的音频分量泄漏到滤波信号中时强调脉冲噪声。
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公开(公告)号：US06690805B1
公开(公告)日：2004-02-10
申请号：US09315035
申请日：1999-05-20
IPC分类号： H04R1500
CPC分类号： H04B1/1661 , H03G3/345
摘要： An audio signal noise reduction system comprises a noise detecting circuit 11 for detecting a noise from an audio signal and outputting a detection signal indicating a start time and an end time of a noise period of the noise, an LPF 12 for extracting a low frequency component of the audio signal, an HPF 14 for extracting intermediate and high frequency components of the audio signal, a polynomial interpolation circuit 13 for polynomial-interpolating the noise period of the low frequency component being extracted, a mute circuit 15 for muting an output level of the noise period of the intermediate and high frequency components being extracted, and a signal synthesizing circuit 16 for synthesizing the low frequency component whose noise period is polynomial-interpolated and the intermediate and high frequency components the level of whose noise period is suppressed to thus output the audio signal.
摘要翻译： 音频信号噪声降低系统包括：噪声检测电路11，用于检测来自音频信号的噪声，并输出表示噪声的噪声周期的开始时间和结束时间的检测信号; LPF12，用于提取低频分量 音频信号的中频和高频分量的HPF14，用于多项式插值所提取的低频分量的噪声周期的多项式插值电路13，用于使音频信号的输出电平静音的静音电路15， 中间和高频分量的噪声周期被提取，以及信号合成电路16，用于合成噪声周期被多项式插值的低频分量，并且中间和高频分量抑制其噪声周期的电平从而输出 音频信号。
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公开(公告)号：US07551743B1
公开(公告)日：2009-06-23
申请号：US09617086
申请日：2000-07-14
IPC分类号： H04B15/00
CPC分类号： G11B20/24 , H04B1/1661
摘要： The FM broadcast is received and the FM demodulated FM composite signal is stereo demodulated, and when the high band components of the demodulated signal are few, the correction is conducted by using the signals just before and just after the noise generation period, and when the high band components are large, the interpolation is conducted by using a central value calculated from the value of a predetermined period before the noise generation period, and a central value calculated from the value of a predetermined period after the noise generation period.
摘要翻译： FM广播被接收并且FM解调的FM复合信号被立体声解调，并且当解调信号的高频带分量很少时，通过使用恰好在噪声产生周期之前和之后的信号来进行校正，并且当 高频带分量较大时，通过使用从噪声产生期间之前的规定期间的值算出的中心值，以及根据噪声产生期间后的规定期间的值计算出的中心值进行插值。
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公开(公告)号：US06664849B1
公开(公告)日：2003-12-16
申请号：US09614680
申请日：2000-07-12
IPC分类号： H03D300
CPC分类号： H03D3/002
摘要： A digital FM demodulator converts a digital FM input signal to a demodulated signal, detects the amplitude of the digital FM input signal, generates a corresponding amplitude signal, and adjusts the amplitude of the demodulated signal according to the amplitude signal, thereby compensating for variations in the amplitude of the digital FM input signal and removing amplitude distortion from the demodulated signal. This reduces the performance requirements of, for example, a low-pass analog filter preceding the digital FM demodulator in an FM radio broadcast receiver, permitting the analog filter to be implemented in a semiconductor integrated circuit.
摘要翻译： 数字FM解调器将数字FM输入信号转换为解调信号，检测数字FM输入信号的幅度，产生相应的幅度信号，并根据振幅信号调整解调信号的幅度，从而补偿 数字FM输入信号的幅度和解调信号的幅度失真。 这降低了例如在FM无线电广播接收机中的数字FM解调器之前的低通模拟滤波器的性能要求，允许模拟滤波器在半导体集成电路中实现。
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公开(公告)号：US06901146B1
公开(公告)日：2005-05-31
申请号：US09723291
申请日：2000-11-28
CPC分类号： H03D3/006
摘要： A stereo composite signal including a pilot signal is demodulated by processing input samples to obtain internal samples having variable sampling timings, synchronizing these sampling timings with the pilot signal, and digitally processing the internal samples to obtain stereo audio data. The internal samples may be obtained from the input samples by decimation or interpolation. Since the sampling frequency and sampling timing of the input samples do not have to be precisely controlled, no voltage-controlled oscillator is needed, and the demodulator can easily be incorporated into a monolithic integrated circuit.
摘要翻译： 通过处理输入样本来解调包含导频信号的立体声复合信号，以获得具有可变采样定时的内部采样，使这些采样定时与导频信号同步，并且数字处理内部采样以获得立体声音频数据。 可以通过抽取或插值从输入样本获得内部样本。 由于不需要精确控制输入采样的采样频率和采样定时，因此不需要压控振荡器，因此解调器可以很容易地集成到单片集成电路中。
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8.发明授权公开(公告)号：US06826392B2
公开(公告)日：2004-11-30
申请号：US10095060
申请日：2002-03-12
IPC分类号： H04B110
CPC分类号： H04B1/1081 , H04B7/005
摘要： A multipath noise reducer extracts a high-frequency signal from a demodulated signal obtained from a frequency-modulated signal, and generates a noise reduction coefficient from the extracted high-frequency signal. The demodulated signal is also separated into high-frequency and low-frequency components, the high-frequency component is multiplied by the noise reduction coefficient, and the resulting product is added to the low-frequency component. An output signal is thereby obtained in which the spike noise that characterizes multipath reception of a frequency-modulated signal is reduced with relatively little distortion of other parts of the signal, including the parts between noise spikes. The distortion can be further reduced by replacing the demodulated signal with an interpolated signal during noise spikes before the low-frequency component is separated.
摘要翻译： 多路径降噪器从从频率调制信号获得的解调信号中提取高频信号，并从所提取的高频信号产生噪声降低系数。 解调信号也分为高频和低频分量，高频分量乘以噪声降低系数，并将所得到的乘积加到低频分量上。 由此获得输出信号，其中表征频率调制信号的多径接收的尖峰噪声通过包括噪声尖峰之间的部分的信号的其它部分的相对较小的失真而减小。 通过在低频分量分离之前的噪声尖峰期间用内插信号替换解调信号，可以进一步减小失真。
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公开(公告)号：US06993309B2
公开(公告)日：2006-01-31
申请号：US09949755
申请日：2001-09-12
IPC分类号： H04B1/10
CPC分类号： H04H40/72 , H04B1/1081 , H04B1/1661
摘要： A noise removal unit mounted on a car radio according to the invention removes multipath noise and pulse noise from FM demodulated signals. At this time, the noise removal unit removes all of the multipath noise. Also, in case where the generation density of noise is high, the noise removal unit reduces the detection sensitivity so as not to detect pulse noise, particularly of small level, as noise. Comparing to multipath noise, pulse noise is noise rendering a large correction error than multipath noise. Therefore, in case where the generation density of pulse noise is high, by adapting the unit not to remove pulse noise of small level, it is made possible to reduce distortion of the FM demodulated signals to a minimum. Accordingly, it is made to reduce deterioration of the quality of FM voices to a minimum.
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公开(公告)号：US06788923B2
公开(公告)日：2004-09-07
申请号：US09783098
申请日：2001-02-15
IPC分类号： H04B110
CPC分类号： H03G3/345
摘要： A noise reducer generates a gate signal by detecting noise in a demodulated signal, and changes the lengths the gate pulses indicating the presence of noise according to the electric-field strength of a radio signal from which the demodulated signal has been obtained. The demodulated signal is modified during intervals indicated by the gate pulses, to reduce the noise. The amount of change of the gate-pulse lengths is preferably increased as the electric-field strength decreases. Noise can then be removed satisfactorily under even weak electric-field conditions.
摘要翻译： 噪声降低器通过检测解调信号中的噪声来产生门信号，并且根据获得解调信号的无线电信号的电场强度改变指示噪声存在的门脉冲的长度。 在由门脉冲指示的间隔期间修改解调信号，以减少噪声。 栅极脉冲长度的变化量优选随着电场强度的降低而增加。 在弱电场条件下，可以令人满意地去除噪声。
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