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公开(公告)号：US5493717A
公开(公告)日：1996-02-20
申请号：US251713
申请日：1994-05-31
申请人： Detlef Schwarz
发明人： Detlef Schwarz
CPC分类号： H03G5/24 , H04B1/1036 , H04B2001/1054
摘要： FM radio receivers, particularly in moving vehicles, are subject to intermittent adjacent-channel interference. It is known to detect such interference and suppress it by narrowing bandwidth in the Intermediate Frequency (IF) signal path. However, it is desirable to again broaden the bandwidth once the interference has subsided. An improved system, which automatically and dynamically adjusts the bandwidth, employs first and second signal level evaluation circuits (11, 12), a comparison stage (13) which compares their outputs, and a variable-bandwidth filter stage (6, 14) controlled by the comparison stage. The comparison stage is programmed with a set of signal difference threshold values and corresponding filter bandwidth values, and controls the filter stage (6, 14) to adjust the bandwidth to the appropriate value, indicated by which signal difference threshold value has been exceeded. In a preferred embodiment, a second IF filter (15) does "double duty" as part of the variable-bandwidth filter stage.
摘要翻译： FM无线电接收机，特别是在移动车辆中，受到间歇性的相邻信道干扰。 已知通过在中频（IF）信号路径中的带宽变窄来检测这种干扰并抑制它。 然而，一旦干扰消退，则期望再次扩大带宽。 采用第一和第二信号电平评估电路（11,12），比较它们的输出的比较级（13）和控制了可变带宽滤波器级（6,14）的改进的系统，其自动和动态地调整带宽 通过比较阶段。 比较级用一组信号差阈值和相应的滤波器带宽值编程，并且控制滤波器级（6,14）将带宽调整到由超过哪个信号差阈值所指示的适当值。 在优选实施例中，第二IF滤波器（15）作为可变带宽滤波器级的一部分进行“双重占空”。
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公开(公告)号：US5537448A
公开(公告)日：1996-07-16
申请号：US205315
申请日：1994-03-02
申请人： Detlef Schwarz , Stefan Bartels
发明人： Detlef Schwarz , Stefan Bartels
CPC分类号： H03L7/107
摘要： An improved Phase-Locked Loop (PLL) radio receiver circuit includes a phase detector, either an active loop filter or a set of parallel, alternately selectable loop filters, and a Voltage-Controlled Oscillator (VCO) whose input is connected to the output of the loop filter. The output of the VCO is fed to frequency divider. The output of the frequency divider and a reference frequency signal form the inputs to the phase detector/comparator. Toggling among the loop filters occurs such that the loop limit frequency, defined by a loop amplification of 1, is altered by this toggling without significantly changing the gradient of the amplification to the frequency, in a frequency range which includes the limit frequency.
摘要翻译： 改进的锁相环（PLL）无线电接收器电路包括相位检测器，有源环路滤波器或一组并行交替可选择的环路滤波器，以及一个电压控制振荡器（VCO），其输入端连接到 环路滤波器。 VCO的输出馈送到分频器。 分频器的输出和参考频率信号形成相位检测器/比较器的输入。 在环路滤波器之间进行切换，使得通过这种切换来改变由环路放大1定义的环路限制频率，而不会在包括极限频率的频率范围内将放大梯度显着地改变为频率。
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公开(公告)号：US5339455A
公开(公告)日：1994-08-16
申请号：US21029
申请日：1993-02-23
申请人： Lothar Vogt , Stefan Bartels , Rainer Arnold , Detlef Schwarz
发明人： Lothar Vogt , Stefan Bartels , Rainer Arnold , Detlef Schwarz
CPC分类号： H03G5/24 , H04B1/1027 , H04B2001/1054
摘要： A mobile radio receiver, for example, a car radio, needs a circuit to detect and suppress adjacent-channel interference. This can be done by using bandpass filters (14) of differing bandwidth. The present invention dynamically adjusts bandwidth to an optimum value by continuously comparing (13) a first signal level, upstream of the bandpass filter, to a second signal level, downstream of the bandpass filter, to derive a difference value representative of adjacent-channel interference, then uses an electronically controlled selector switch (6) to select a particular filter (14.sub.N) whose bandwidth is sufficiently narrow to cut out the interfering broadcast signal. A table associating each magnitude range of interference with a particular filter bandwidth assures that bandwidth is broadened as interference diminishes, thereby assuring sufficient reception signal strength.
摘要翻译： 诸如汽车无线电的移动无线电接收机需要电路来检测和抑制相邻信道干扰。 这可以通过使用不同带宽的带通滤波器（14）来完成。 本发明通过将带通滤波器的上游的第一信号电平（13）与带通滤波器的下游的第二信号电平连续地进行比较，将带宽动态地调整为最佳值，以导出表示相邻信道干扰的差值 ，然后使用电子控制的选择器开关（6）来选择其带宽足够窄的特定滤波器（14N）以切断干扰广播信号。 将每个幅度范围的干扰与特定滤波器带宽相关联的表格确保了随着干扰减小而使带宽变宽，从而确保足够的接收信号强度。
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