公开(公告)号：US4864639A

公开(公告)日：1989-09-05

申请号：US101488

申请日：1987-09-28

申请人： Mark A. Dapore ,  Daniel A. Titus

发明人： Mark A. Dapore ,  Daniel A. Titus

IPC分类号： H03J1/00 ,  H03J3/32 ,  H03J7/02 ,  H03J7/28 ,  H04B1/16

CPC分类号： H03J7/02 ,  H03J3/32 ,  H03J7/28 ,  H04B1/16 ,  H03J1/0008

摘要： An FM receiver is self tested by connecting a positive feedback network in circuit with a wideband, front end r.f. amplifier of the receiver, so that the amplifier is converted into an oscillator. R.f. and i.f. characteristics of the receiver are determined by comparing the amplitude of an i.f. signal with a predetermined reference value while the amplifier is converted to an oscillator. Noise characteristics of the receiver are determined by comparing the amplitude of an audio frequency signal of the receiver with a predetermined value while the amplifier is converted to an oscillator and the amplifier derives an unmodulated r.f. output. Baseband characteristics of the receiver are determined by varying a reactance in the positive feedback path to impose FM on r.f. oscillations derived by the amplifier and by comparing the amplitude of the output of the audio frequency amplifier with a predetermined value. By varying the value of the reactance in the feedback loop, the oscillating frequency is swept to determine the center operating frequency and i.f. bandwidth of the r.f., amplifier.

摘要翻译： FM接收机通过将电路中的正反馈网络与宽带前端r.f.连接进行自检。 放大器，使放大器转换为振荡器。 R.f. 而如果。 通过比较i.f的振幅来确定接收机的特性。 当放大器转换为振荡器时，具有预定参考值的信号。 通过将放大器转换为振荡器并且放大器导出未调制的r.f，将接收机的音频信号的幅度与预定值进行比较来确定接收机的噪声特性。 输出。 接收机的基带特性通过改变正反馈路径中的电抗来对FM施加r.f.来确定。 并且通过将音频放大器的输出的幅度与预定值进行比较来产生振荡。 通过改变反馈回路​​中的电抗值，扫描振荡频率以确定中心工作频率和i.f. r.f.，放大器的带宽。