| 摘要 |
1,250,777. Automatic phase control, transistor oscillators and ramp generators. WESTERN ELECTRIC CO. Inc. 11 Dec., 1968 [13 Dec., 1967], No. 58795/68. Headings H3A and H3T. A phase locked oscillator system comprises a voltage controlled oscillator 310 and a phase comparator which includes a ramp generator 320. Means are provided for increasing the duration of the ramp function if the error signal from the comparator is indicative of a phase error exceeding a predetermined value. An output pulse from oscillator 310 switches on transistor 341 to charge capacitor 344 and at the end of the pulse, capacitor 344 commences to discharge, at a rate determined by transistor 345. Whenever a reference pulse is received on line 331, gate 330 opens, and the potential on capacitor 344 at that instant is transferred to capacitor 332 to provide an error signal indicative of the time interval between the oscillator output pulse and the reference output pulse. This error signal is fedback over line 312 to control the oscillator frequency. If the frequency drifts outside the lock-in range, the error signal falls to zero, and transistor 362 conducts to change the conductivity of transistor 345, thus increasing the duration of the ramp function produced by the discharge of capacitor 344. An error signal is thus once again produced to cut off transistor 362, after which the charge on capacitor 391 slowly leaks away allowing the conductivity of transistor 345 to revert to its normal value and reduce the duration of the ramp function again. Oscillator 310.-Capacitor 340 charges through. constant current source 321 at a rate determined by the control voltage on line 312, and the setting of potentiometer 311 until transistor 313 conducts. The output from 313 switches on a monostable blocking oscillator 317 which produces an output pulse which in turn triggers a similar blocking oscillator 336. The output pulse from 336 turns on transistor 329 to discharge capacitor 340, and the cycle then repeats. |
