| 摘要 |
PURPOSE:To make unnecessary the reed filter and to establish the indentifier low in cost and high in reliability, by the identification through the use of the detection signal in response to difference between the detection output frequency of pilot signal and the reference signal frequency. CONSTITUTION:The composite signal is inputted to BPF1 to select and pick up the pilot signal fA and to obtain the single tone signal from the AM detector 2, and it is inputted to the wave shape circuit 4 via BPF3 to form the rectangular pulse signal fT. On the other hand, the signal fA is converted into rectangular pulse with the wave shape circuit 5, fed to the 1/64 frequency dividing unit 6 to form the reference signal fQ. The signals fQ and fT are inputted to D-FF7 to output the signal fD having the frequency of the difference between the both signals. The frequency of the signal fD is detected at the counter in cascade connection of FF8 and 9. The output of the detector 11 detecting the pilot signal and the output of FF9 through logical product are output of the AND gate 12 to obtain bilinguial control signal, and the logical product of the output of the inverter 13 inverting the output of FF9 and the output of the detector 11 is obtained from the output of the AND gate 14 to obtain stereo control signal. |
