| 摘要 |
PURPOSE:To expand follow-up range without increasing jitters of demodulation carrier for synchronous detection, by expanding the frequency variable range by cascading two frequency control circuits. CONSTITUTION:Input carrier A is multiplied 1 by demodulation cariers B1 and B2, and results are inputted to LPF2. Phase detection outputs C1 and C2 are compared 4 each other and led to polarity decision circuit 5, where its polarity is discriminated by the control signal of receiving logic part 3. Frequency control circuit 6 is altered as shown in the figure. Frequency control circuit 10 inserts or deletes one pulse into or from a higher clock at every 1st sampling pulse S1 in the same way as circuit 6. Frequency control circuit 11, on the other hand, inserts or deletes one pulse into or from the output clock D2 of circuit 10 at every 2nd sampling pulse S2. Therefore, the total frequency variable range can be expanded corresponding to the frequency variable range by circuit 11. |
