| 摘要 |
PURPOSE:To reduce the number of parts to lower the cost by omitting a lead filter which separates a pilot signal discriminating a stereophonic broadcast or a different program broadcast. CONSTITUTION:In the demodulator circuit which demodulates TV voice multiple cmposite signals including 55.125K Hz pilot signals which were modulated at 982.5Hz at a stereophonic time and were AM-modulated at 922.5Hz at a different program time, lead filter 4 is provided which takes out frequency 922.5 or 98.25Hz from the pilot signal detection output. Then, the output of AM detector circuit 3 is applied to Schmitt circuit 6 through filter 4, and demodulator circuit 1 is switched to the different program or the stereophonic program broadcast according to the frequency of filter 4. Meanwhile, switch 8 is operated by the output of decision circuit 10 which is detected by pilot signal detector circuit 2, and the output of Schmitt circuit 7 is applied to demodulator circuit 1 through switch 8, thereby switching to the demodulation of the broadcast opposite to the frequency of filter 4. |
