| 摘要 |
PURPOSE:To hold the period stability of the 2nd pulse generators by counting pulses generated by the 1st pulse generator with period stability and the 2nd pulse generator which is easy to start, and correcting the period of the 2nd pulse generator. CONSTITUTION:A received burst signal A is supplied to a start pulse detecting circuit 1 to detect a start pulse signal B, which is applied to the 2nd pulse generating circuit 3 as a voltage-controlled oscillator. The circuit 3 stops the generation of pulses by the signal B and restarts the generation when the signal B is ceased, and its signal C is counted by a counter 6. The signal B is inputted to a gate 4 to inhibit a signal D from the 1st pulse generating circuit 2 as a crystal oscillator, and the output signal D' of the gate 4 is counted by a counter 5. A counter having a greater value between the counters 5 and 6 clears the other counter to set or reset an FF7 according to their outputs E and F, and the FF7 decides on whether the generated number of pulses is great or not. Its decision signal G is inputted through an LPF8 to the circuit 3 to control a pulse generation period, and thus the signal C is allowed to follow up the signal D, holding the period stability of the signal C. |
