| 摘要 |
PURPOSE:To always obtain a satisfactory receiving condition without being affected by an interference such as beat from an adjacent central office, by automatically switching the upper side-band and the lower side-band in accordance with a receiving condition. CONSTITUTION:The output terminal which can obtain a lower side-band detection signal of the matrix circuit 11 is connected to the detection circuit 21 through the band-pass filter 20 for lower side-band, also the output terminal which can obtain an upper side-band detection signal of the circuit 11 is connected to the detection circuit 23 through the band-pass filter 22 for upper side-band, the output sides of the detection circuits 21, 23 are connected to each base of the transistors 24, 25 constituting the differential amplifiers, respectively, each collector is connected to the positive power source terminal +B through the resistor 26 and the light emission diode 27 for displaying the upper side-band receiving, and the resistor 28 and the light emission diode 29 for displaying the lower side-band receiving, and the emitters of the transistors 24, 25 are grounded through the constant-current source 30. |
