US PATENT SUBCLASS 455 / 255
.~.~ Local oscillator frequency control

Current as of: June, 1999
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455 /   HD   TELECOMMUNICATIONS

130  DF  RECEIVER OR ANALOG MODULATED SIGNAL FREQUENCY CONVERTER {24}
230  DF  .~ Local control of receiver operation {7}
255.~.~ Local oscillator frequency control {2}
256  DF  .~.~.~> Combined with other control
257  DF  .~.~.~> Automatic {2}

DEFINITION

Classification: 455/255

Local oscillator frequency control:

(under subclass 230) Subject matter including one or more local oscillators combined with means to adjust the generated frequency thereof or with a control circuit or loop for controlling the oscillator frequency adjusting means in response to deviation of the generated oscillator frequency 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.

(1) Note. The control circuit or loop includes: (a) discriminator means for sensing the deviation of the generated frequency of the oscillator, or oscillators, in direction and amount and for producing control energy proportional to such deviation, and (b) means responsive to the control energy and coupled to frequency adjusting means of the oscillator, or oscillators, to the desired frequency or range of frequencies whereby the intermediate frequency output of a mixer means, to which the output of the oscillator, or oscillators, is applied will remain constant at a given frequency or range of frequencies.

SEE OR SEARCH THIS CLASS, SUBCLASS:

147, for panoramic type receivers with local oscillator control means.

196.1+, for wave selection (i.e., tuning) means combined with local oscillator tuning means.

208+, for phase or frequency modulation type receivers with synchronized or controlled local oscillator means.

226, for measuring, testing, or calibrating apparatus for receivers which may include oscillator control means.

316, for wave or modifying or conversion systems with frequency stabilization means for at least one local oscillator. SEE OR SEARCH CLASS

332, Modulators,

123+, for controlling an average condition of a frequency modulator and subclasses 155+ and 161+ for controlling an average condition of an amplitude modulator.