(under the class definition) Subject matter wherein the oscillator has means to adjust its generated frequency and is also provided with a control circuit or loop for controlling the oscillator frequency adjusting means in response to deviation of the generated frequency of the oscillator from a desired frequency or range of frequencies in such direction and amount as to restore the oscillator frequency to the desired frequency or range of frequencies. The control circuit or loop includes: (1) discriminator means for sensing the deviation of the generated frequency of the oscillator in direction and amount and for producing control energy proportional to such deviation, and (2) means responsive to the control energy and coupled to frequency adjusting means of the oscillator to vary the frequency adjusting means in such direction and amount as to restore the generated frequency of the oscillator to the desired frequency or range of frequencies.
(1) Note. The automatic frequency stabilizing systems defined above are to be distinguished from the frequency stabilizing systems classified lower in the schedule (see the
search notes below) by the fact that the A.F.S. systems rely on sensing a drift in frequency of the generated oscillations and asserting a corrective control to adjust a frequency determining element of the oscillator in the proper sense to bring it back on frequency, whereas the frequency stabilizing systems classified elsewhere do not sense a drift of frequency and retune the oscillator as a function of such drift, but rely on adding means to the oscillator system to correct or compensate, or to prevent, changes in oscillator circuit parameters that tend to cause an undesired change in oscillator frequency. Such means may, for example, compensate for the affects of changes in humidity, temperature, current load impedance, tube impedance, electrode bias potential, etc.
SEE OR SEARCH THIS CLASS, SUBCLASS:
41, for beat frequency oscillators with frequency stabilizing means. See also, (1) Note, above.
88, for magnetron type oscillators with frequency stabilizing means. See, also, (1) Note, above.
175+, for oscillators in general with frequency stabilizing means. See, also (1) Note, above. SEE OR SEARCH CLASS
322, Electricity: Single Generator Systems,
32, for dynamoelectric generator systems with frequency responsive devices or networks for automatically maintaining the frequency of the generated wave constant.
329, Demodulators,
315+, for frequency demodulators and subclasses 345+ for phase demodulators.
332, Modulators,
123+, for average condition control in frequency modulator distortion prevention and subclasses 155+ and 159+ for average condition control in an amplitude modulator.
334, Tuners,
13, for a tuner having a saturable core element combined with means to automatically center the frequency of the circuit; subclass 16 for a tuner having a reactance tuning means combined with automatic frequency centering means, and subclasses 26+ for tuners having an electromagnetic operator combined with automatic frequency centering means.
348, Television,
536+, for synchronizing systems which may utilize oscillators
of the automatic frequency stabilized type and subclass 735 for television tuners which may utilize oscillators of the automatic frequency stabilized type. 375, Pulse or Digital Communications,
354+, for synchronizing systems which may use oscillators of the automatic frequency stabilized type.
455, Telecommunications,
91+, for radio transmitters using oscillators of the automatic frequency stabilized type; and subclasses 130+ for receivers using oscillators of the automatic frequency stabilized type.
