US PATENT SUBCLASS 455 / 280
.~.~ With coupling to a stage of the receiver

Current as of: June, 1999
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455 /   HD   TELECOMMUNICATIONS

130  DF  RECEIVER OR ANALOG MODULATED SIGNAL FREQUENCY CONVERTER {24}
269  DF  .~ With wave collector (e.g., antenna) {4}
280.~.~ With coupling to a stage of the receiver {7}
281  DF  .~.~.~> Having distributed parameters {1}
283  DF  .~.~.~> Undesired signal or noise control (e.g., antistatic) {5}
289  DF  .~.~.~> With coupling varying, regulating, or control
290  DF  .~.~.~> Including passive tuned circuit
291  DF  .~.~.~> Using active device (e.g., as preamplifier or reactance)
292  DF  .~.~.~> Transformer or other passive inductance
293  DF  .~.~.~> Specified stage (e.g., mixer, amplifier, or demodulator) {1}

DEFINITION

Classification: 455/280

With coupling to a stage of the receiver:

(under subclass 269) Subject matter including wave collector and a receiver stage coupled by a specified coupling means.

(1) Note. For purposes of classification in this class a tuned circuit connected between the grid and cathode of a tube and variably tunable will be considered as a preselector stage and not a part of the collector coupling circuit. Subject matter relating to preselector circuit means will be found in this class (455) subclass 193.1.

(2) Note. The word detector as defined in this and the indented subclasses will refer to a demodulator means and is not to be confused with mixer means sometimes referred to in the patent literature as a first detector with the demodulator being referred to as a second detector. In this and other subclasses in this class the word detector when used will always denote the demodulator or second detector means. Note that prior to the advent of the heterodyne type of receiver the antenna was usually connected directly to a radio frequency amplifier-detector means or detector means along with the output connected directly to some utilization means such as headphones.

(3) Note. Class 329, Demodulators, contains some demodulators combined with other elements such as an amplifier or speaker. The search notes to that class under the general class definition list combinations considered as classifiable in Class 329 and elsewhere. It will be noted that this Class is specifically mentioned as the proper place for "radio receivers generally including combinations of antennas and detectors or demodulators" and superheterodyne detectors (i.e., mixers).

(4) Note. As an example of the difference between subject matter to be found in this and indented subclasses and that to be found in this class under signal selection based on frequency, subclasses 150.1+ let it be assumed (a) that the system claimed or disclosed consists of a collector circuit

including the primary of an inductive transformer, one terminal of which is connected to ground and the other in a closed loop including the collector, or (b) a tunable circuit including the secondary of the input transformer and an amplifier having the tunable circuit connected between the grid and cathode thereof. For classification purposes in this subclass the collector loop circuit including the primary winding of the transformer (a) will be considered as a particular coupling circuit (i.e., transformer) between the collector and amplifier and will be found in subclass 292. The tunable circuit in the input of the tube means which also includes a winding of the transformer (i.e., secondary) (b) will be considered as a wave selecting means in combination with an amplifier means and will be found in subclasses 150+.

SEE OR SEARCH THIS CLASS, SUBCLASS:

129+, for transmitters with coupled antenna. 214+, for frequency or phase modulation receivers with particular discriminator.

313+, for receiver including particular wave conversion or mixer means.

337, for receiver including particular discriminator means.

341+, for receiver including particular amplifier means.

SEE OR SEARCH CLASS

178, Telegraphy,

2, for miscellaneous telegraphy systems which may comprise an antenna combined with detector or amplifier means.

315, Electric Lamp and Discharge Devices: Systems,

34, for electric lamp and discharge lead devices having an antenna combined therewith as a unitary structure and not otherwise classifiable.

329, Demodulators, appropriate subclasses for demodulator systems, per se.

330, Amplifiers, appropriate subclasses for amplifiers, per se.

331, Oscillators, 37+, for beat frequency oscillator, per se.

332, Modulators, appropriate subclasses for modulators, per se.

343, Communications: Radio Wave Antennas, appropriate

subclasses for radar, receivers consisting of an antenna combined with detector or other means. Search also

850+, for antenna structure combined with a coupling network or impedance in the leading. The leading is defined in the definition of Class 343 as being, "a conductive means for conveying the signal energy between the active antenna and the signal source or receiver.