| 摘要 |
PROBLEM TO BE SOLVED: To obtain the FM sound signal reproducing circuit in which the occurrence of unpleasant sound due to a narrow track width and a small azimuth effect is prevented by means of a comparatively simple method, even in the case of reproduction in the NTSC LP mode. SOLUTION: Resistors 37, 47 are provided respectively between LP de- emphasis circuits 36, 46 and low pass filters 39, 49, and an external terminal is provided to a connection point between a resistor 47 of a main reproduction means and the low-pass filter 49. An externally mounted capacitance 56 is provided to the external terminal during the sound reproduction, selected by a digital transistor 55 and inserted between ground and the external terminal. Thus, with the comparatively simple method in the case of the reproduction in the NTSC system LP mode by using a conventional reproduction circuit of an FM audio IC, high frequency components of stereophonic sum signals are attenuated to reduce noise due to a narrow track width. |
