| 摘要 |
PURPOSE:To store the preceding information after encoding, by reading out a control signal stored on the occasion of a good S/N ratio from a memory and controlling an oscillating frequency until the control information having the good S/N ratio can be acquired again. CONSTITUTION:The condition that a noise output from a frequency discriminator 6 is samll is detected at a threshold level or more, this is picked up via a low- pass filter 7 and inputted to a sample holding circuit 9 to store the output voltage. The voltage is encoded at an AD coverter 10 and stored in a memory circuit 11. The stored signal is converted into a DC output at a DA converter 12 and stored in a sample holding circuit 13a, this output is amplified at a limiter amplifier 15 and applied to a varactor diode 3 for AFC control. If the reception input is decreased, the memory 11 is read out and tentatively stored in a sample holding circuit 13a and this output performs the AFC control. |
