公开(公告)号：US4151472A

公开(公告)日：1979-04-24

申请号：US851374

申请日：1977-11-14

申请人： Eiji Watanabe ,  Junichi Onozawa ,  Jouji Tanaka ,  Takazo Takahashi ,  Tsuneo Kitamura ,  Hiroshi Yamada ,  Hiroshi Noguchi ,  Yukio Ueno

发明人： Eiji Watanabe ,  Junichi Onozawa ,  Jouji Tanaka ,  Takazo Takahashi ,  Tsuneo Kitamura ,  Hiroshi Yamada ,  Hiroshi Noguchi ,  Yukio Ueno

IPC分类号： H04Q1/30 ,  G01R15/09 ,  G01R23/00 ,  G08B3/10 ,  H04Q7/16 ,  H03K17/26 ,  H03K5/18

CPC分类号： G01R15/09 ,  G01R23/005 ,  G08B3/1008

摘要： In a selective calling circuit including a band-pass filter which may be constituted by an active filter, and a power source for energizing the filter, a control signal is generated which has a predetermined duration in accordance with the output of the band-pass filter at a point of time whereat the output of the band-pass filter reaches a predetermined level. In response to the control signal, there is established a state in which the center frequency of the band-pass filter can be changed, and the output of the power source is changed from a first level to a second level for a period of time substantially corresponding to the predetermined duration of the control signal. At the aforementioned first level, the band-pass filter may be energized, while at the second level, it may be deenergized.

摘要翻译： 在包括可由有源滤波器构成的带通滤波器和用于激励滤波器的电源的选呼电路中，产生根据带通滤波器的输出具有预定持续时间的控制信号 在带通滤波器的输出达到预定电平的时间点。 响应于控制信号，建立了可以改变带通滤波器的中心频率并且将电源的输出从第一电平改变到第二电平一段时间的状态 对应于控制信号的预定持续时间。 在上述第一级，带通滤波器可以被激励，而在第二级，它可以被断电。