| 摘要 |
PURPOSE:To shorten a measurement time by measuring the frequency characteristics of a station detector (SD) only by a DC power source and a DC voltmeter. CONSTITUTION:Voltage values of input terminals 5 and 6 of an FM detecting circuit 2 are measured by DC voltmeters 9 and 10 to obtain voltage values V1 and V2. The band width of the DS is so set that a frequency higher than the center frequency f0 is f02 and a lower frequency is f01. Switching circuits 7 and 8 are placed at sides 7'' and 8'' to apply the voltage V1 to a terminal 5 and the an offset voltage corresponding to the voltage value V2 and frequency f01 to a terminal 6, and consequently the voltage corresponding to the frequency f01 appears at the output terminal 12 of an SD output circuit 3. The indication of a DC voltmeter 13 is compared with a specification value to decide whether the voltage value is normal or not. Then, when the voltage values of power sources 11 and 12 are set to said voltage values V1 and V2, the voltage of frequency f0 appears at a terminal 12 and the indication of the voltmeter 13 is compared with the specification value to decide whether the voltage value is normal or not. Further, a measurement is taken similarly as to the frequency f02 to make a decision as mentioned above. Consequently, the frequency characteristics of the SD output are tested only on DC basis, so the measurement time is shortened.
|
