US PATENT SUBCLASS 455 / 257
.~.~.~ Automatic

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  DF  .~.~ Local oscillator frequency control {2}
257.~.~.~ Automatic {2}
258  DF  .~.~.~.~> Utilizing particular local oscillator control {4}
265  DF  .~.~.~.~> With local oscillator synchronization or locking

DEFINITION

Classification: 455/257

Automatic:

(under subclass 255) Subject matter wherein the control means consists of a self-acting control circuit or loop whereby the output frequency of the oscillator means or the output of the mixer means is maintained constant at a desired frequency or within a desired frequency range. The control circuit or loop generally includes discriminator means for sensing the deviation of the oscillator output frequency in direction and amount with means for producing a control energy corresponding to the sensed deviation and applying the generated control energy to a controlling means in the oscillator circuit in the proper sense or direction to restore the oscillator output frequency to a desired value.

(1) Note. Systems wherein the frequency deviation of the output of the conversion means (i.e., intermediate frequency) is sensed and a control energy applied in such a direction as to compensate for the deviation are also found here.

SEE OR SEARCH CLASS

331, Oscillators,

1+, for similar subject matter relating to oscillator systems of general utility having automatic frequency stabilization means. See Lines With Other Classes and Within That Class, and References to Other Classes, in the class definition of Class 331 and the search notes under subclass 1 of that class.