| 摘要 |
PURPOSE:To offer a PRI filter tuned to a pulse repetitive interval PRI automatically to an incoming pulse train by applying an operation to an output and feeding back the result so as to control a delay time of a delay circuit. CONSTITUTION:A delay time T of a delay circuit 6 is decided by the rule of control dT/dt=Gx, where x is an output of an LPF11 and G is a control gain. A code (k) is generated from an output of the k-th stage (-K<=k<=K) of a shift register 7 by a code generator 8. The timing of generation is produced after T+k , where is the delay time per one stage of the register 7. The code is added at an adder 9 by an interval of and multiplied with a multiplier 10 further. Each incoming pulse is outputted from the multiplier 10 only when a pulse preceding by T+K + or -K from the pulse exists, and a DC component (x) is extracted by the LPF11. When x>0, it represents that the PRI of the incoming pulse train is deviated upward of T+K and when x<0, it represents that the PRI is deviated downward. Thus, when the delay time T is controlled by the rule of control, the T+K approaches the PRI of the incoming pulse train as the time is elapsed. |
