| 摘要 |
PCT No. PCT/FI95/00564 Sec. 371 Date Jun. 12, 1996 Sec. 102(e) Date Jun. 12, 1996 PCT Filed Oct. 11, 1995 PCT Pub. No. WO96/12348 PCT Pub. Date Apr. 25, 1996A signal of a locking detector of a synthesizer indicates in a first state that a loop is locked, and in a second state that the loop is unlocked. The synthesizer may be temporarily deactivated by switching off the operating voltage of a voltage controlled oscillator by means of a switching signal. The alarm circuit of the synthesizer includes a first detector, a state of the output of which changes with a delay, in response to the change of the signal of the detector conveyed to the detector, and a second detector, the state of the output of which changes with a delay, in response to the change of the switching signal conveyed to the detector, and a device generating the alarm signal. The device provides the output signal of the alarm circuit in response to the output signals of the detectors. By selecting appropriate delay-times for the detector, it is possible to achieve the intended operation.
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