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公开(公告)号：US5175508A
公开(公告)日：1992-12-29
申请号：US802686
申请日：1991-12-05
摘要： A voltage-controlled amplifier employs an operational amplifier with negative feedback for setting the gain. A voltage variable resistance such as a junction-field-effect transistor (JFET) is employed as part of a variable voltage divider for controlling the amplifier gain. Resistors in series and in parallel with the JFET determine minimum and maximum resistances corresponding to upper and lower limits for the amplifier gain. Thus, multiple channels of an amplifier can be provided with closely matched characteristics even using separate JFETs in each separate channel which have unmatched characteristics.
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公开(公告)号：US5138280A
公开(公告)日：1992-08-11
申请号：US802590
申请日：1991-12-05
CPC分类号： H03G1/007 , H03G3/3015
摘要： A multichannel amplifier employs field-effect transistors to vary the gain of operational amplifiers in each respective channel. Gain matching of the respective channels is obtained by providing each channel with a respective DC bias voltage which compensates for differences in pinch-off voltage of the field-effect transistors. The invention permits the use of inexpensive, unmatched JFETs in the amplifier. Close gain tracking achieves very accurate stereo imaging in an audio system.
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公开(公告)号：US5400188A
公开(公告)日：1995-03-21
申请号：US162548
申请日：1993-12-06
IPC分类号： G11B15/087 , G11B27/22 , G11B5/09
CPC分类号： G11B27/22 , G11B15/087
摘要： Digital signal processing (DSP) employing a differential mean calculation automatically distinguishes sections of blank tape from program material (such as music or voice) on cassette tapes. Blank tape produces a negligible differential mean value while program material produces substantial differential mean values. Thus, each differential mean is compared to a threshold so that a cassette player can be commanded to fast forward through a blank section of tape. A music envelope detector insures that low amplitude music signals are not detected as blank.
摘要翻译： 使用差分均值计算的数字信号处理（DSP）会自动区分空白磁带的部分与录像带上的节目素材（如音乐或声音）。 空白胶带产生可忽略的微分平均值，而程序材料产生实质的差分均值。 因此，将每个差分均值与阈值进行比较，使得可以命令盒式播放器快速前进通过磁带的空白部分。 音乐包络检测器确保低振幅音乐信号不被检测为空白。
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公开(公告)号：US5469510A
公开(公告)日：1995-11-21
申请号：US82633
申请日：1993-06-28
申请人： Henry F. Blind , Anthony J. Campagne , James L. Czekaj , Nicholas L. Difiore , Earl R. Geddes , Andrew C. Krochmal , Myron I. Senyk
发明人： Henry F. Blind , Anthony J. Campagne , James L. Czekaj , Nicholas L. Difiore , Earl R. Geddes , Andrew C. Krochmal , Myron I. Senyk
IPC分类号： B60R11/02 , G10K11/178 , H03G3/20 , H03G3/32 , H03G5/16 , H03G9/02 , H03G11/00 , H03H17/00 , H03H21/00 , H04B3/04
摘要： An acoustic production system having multiple signal sources and a power amplifier driving an acoustic transducer such as a loudspeaker includes an arbitrator in a power limiter circuit to selectively limit the input level of one of the sources to the power amp in response to an overdrive signal from the amplifier. The input level to the power amplifier is automatically reduced in response to the overdrive signal until a predetermined level of limiting has been attained. Once the predetermined level of limiting is reached, the arbitrator outputs a second overdrive signal to prompt additional limiting of the power amplifier output. Preferably, the arbitrator is included in an interior active noise cancellation module combined with an audio entertainment system for a passenger compartment of a motor vehicle. The audio system also preferably separates the audio reproduction into high frequency and low frequency branches, whereby the arbitrator acts upon the signals output in the frequency ranges of active noise cancellation and the bass output of the audio entertainment system that are most likely to overdrive an amplifier.
摘要翻译： 具有多个信号源的声学生产系统和驱动诸如扬声器之类的声学换能器的功率放大器包括：功率限制器电路中的仲裁器，用于响应于来自第二个信号的过驱动信号选择性地将功率放大器的一个源的输入电平限制到功率放大器 放大器。 功率放大器的输入电平响应于过驱动信号而自动减小，直到达到预定的限制水平。 一旦达到预定的限制电平，则仲裁器输出第二过驱动信号以提示功率放大器输出的附加限制。 优选地，仲裁者被包括在与用于机动车辆的乘客舱的音频娱乐系统相结合的内部主动噪声消除模块中。 音频系统还优选地将音频再现分离成高频和低频分支，由此仲裁器对在最有可能过度驱动放大器的有源噪声消除和音频娱乐系统的低音输出的频率范围中输出的信号起作用 。
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