Search-lock system |
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| 申请号 | US3758866D | 申请日 | 1972-04-03 | 公开(公告)号 | US3758866A | 公开(公告)日 | 1973-09-11 |
| 申请人 | US NAVY; | 发明人 | HANSEN N; ORENSTEIN N; | ||||
| 摘要 | A received RF signal is mixed with the output of a voltagecontrolled local oscillator to provide an IF signal which is simultaneously passed to a frequency discriminator and a circulating memory. Control voltage for the oscillator is provided by an AFC unit which comprises an integrator receiving selected contant voltage inputs. During the search mode a search ramp is generated by the integrator. A flyback circuit causes the search voltage to repeat its traverse over a prescribed range. Bipolar video discriminator outputs above a predetermined threshold place the system in the lock mode and selectively gate two settable, constant voltage inputs to furnish a triangle wave integrator output centered on a voltage corresponding to the desired local oscillator frequency. The oscillator output is mixed with the stored IF to produce a replica of the input signal. | ||||||
| 权利要求 | 1. An automatic frequency controller responsive to a bipolar input signal, comprising: search generator means for producing two output signals having alternately high voltages of predetermined amplitudes, and for receiving the bipolar input signal for inhibiting the low voltage when the bipolar input signal is of one polarity; correction generator means for receiving the bipolar input signal for producing two output signals having high and low voltages of predetermined amplitudes in accordance with the said one polarity and another polarity, respectively, of the bipolar input signal; integrator means connected to receive said search generator means output signals and said correction generator means output signals for producing an output signal indicative of the integration thereof, the integrator means output signal further connected to said search generator means for alternately switching the search generator means output signals; and voltage controlled oscillator means operatively connected to receive the integrator means output signal for producing an output signal having a frequency which is a function of the bipolar input signal. 2. An automatic frequency controller according to claim 1 wherein: said search generator means comprises first and second voltage supply means for producing respectively the high and low voltages, said second voltage supply means connected for receiving the bipolar input signal for inhibiting the low voltage, and limit detector means connected to receive the integrator means output signal for activating the first and second supply means respectively in response to a first or second predetermined level of the output signal. 3. An automatic frequency controller according to claim 2 wherein: said correction generator means comprises third and fourth voltage supply means for producing respectively the high and low voltages, and switch means connected to receive the bipolar input signal for activating the third and fourth supply means respectively in response to said one polarity or said other polarity. 4. An automatic frequency controller according to claim 3 wherein: said one polarity of said bipolar input signal is positive; and said other polarity of said bipolar input signal is negative. |
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