|  | H |
SECTION H — ELECTRICITY

|  | H03 |
BASIC ELECTRONIC CIRCUITRY

|  | H03B |
GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS (measuring, testing Fulltext... Hierarchy... Expanded...G01R; generators adapted for electrophonic musical instruments Fulltext... Hierarchy... Expanded...G10H; synthesis of sound waves Fulltext... Hierarchy... Expanded...G10L; masers, lasers Fulltext... Hierarchy... Expanded...H01S; dynamo-electric machines Fulltext... Hierarchy... Expanded...H02K; power inverter circuits Fulltext... Hierarchy... Expanded...H02M; by using pulse techniques Fulltext... Hierarchy... Expanded...H03K; automatic control of generators Fulltext... Hierarchy... Expanded...H03L; starting, synchronisation or stabilisation of generators where the type of generator is irrelevant or unspecified Fulltext... Hierarchy... Expanded...H03L; generation of oscillations in plasma Fulltext... Hierarchy... Expanded...H05H)

|  | H03C |
MODULATION (measuring, testing Fulltext... Hierarchy... Expanded...G01R; masers, lasers Fulltext... Hierarchy... Expanded...H01S; modulators specially adapted for use in dc amplifiers Fulltext... Hierarchy... Expanded...H03F 3/38; modulating pulses Fulltext... Hierarchy... Expanded...H03K 7/00; pulse code modulation Fulltext... Hierarchy... Expanded...H03K 13/00; so-called modulators capable only of switching between predetermined states of amplitude, frequency or phase Fulltext... Hierarchy... Expanded...H03K 17/00, Fulltext... Hierarchy... Expanded...H04L; synchronous modulators specially adapted for colour television Fulltext... Hierarchy... Expanded...H04N 9/50)

|  | H03C |
Note(s) This sub-class deals only with modulation, keying, or interruption of sinusoidal oscillations or electromagnetic waves, the modulating signal having any desired waveform. In this sub-class, circuits usable both as modulator and demodulator are classified in the group dealing with the type of modulator involved.

|  | H03D |
DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER (masers, lasers Fulltext... Hierarchy... Expanded...H01S; circuits capable of acting both as modulator and demodulator Fulltext... Hierarchy... Expanded...H03C; details applicable to both modulators and frequency-changers Fulltext... Hierarchy... Expanded...H03C; demodulating pulses Fulltext... Hierarchy... Expanded...H03K 9/00; transforming types of pulse modulation Fulltext... Hierarchy... Expanded...H03K 11/00; pulse code modulation Fulltext... Hierarchy... Expanded...H03K 13/00; repeater stations Fulltext... Hierarchy... Expanded...H04B 7/14; demodulators adapted for ac systems of digital-information transmission Fulltext... Hierarchy... Expanded...H04L 27/00; synchronous demodulators adapted for colour television Fulltext... Hierarchy... Expanded...H04N 9/50)

|  | H03D |
Note(s) This sub-class deals only with (a) demodulation or transference of signals modulated on a sinusoidal carrier or on electromagnetic waves, and (b) comparing phase or frequency of two mutually-independent oscillations.

|  | H03F |
AMPLIFIERS (measuring, testing Fulltext... Hierarchy... Expanded...G01R; optical parametric amplifiers Fulltext... Hierarchy... Expanded...G02F; circuit arrangements with secondary emission tubes Fulltext... Hierarchy... Expanded...H01J 43/30; masers, lasers Fulltext... Hierarchy... Expanded...H01S; control of amplification Fulltext... Hierarchy... Expanded...H03G; coupling arrangements independent of the nature of the amplifier, voltage dividers Fulltext... Hierarchy... Expanded...H03H; amplifiers capable only of dealing with pulses Fulltext... Hierarchy... Expanded...H03K; repeater circuits in transmission lines Fulltext... Hierarchy... Expanded...H04B 3/36, Fulltext... Hierarchy... Expanded...H04B 3/58; application of speech amplifiers in telephonic communication Fulltext... Hierarchy... Expanded...H04M 1/60, Fulltext... Hierarchy... Expanded...H04M 3/40)

|  | H03F |
Note(s) This sub-class deals with (a) linear amplification, there being linear relationship between the amplitudes of input and output, and the output having substantially the same waveform as the input, (b) dielectric amplifiers, magnetic amplifiers, and parametric amplifiers when used as oscillators or frequency-changers, and (c) constructions of active elements of dielectric amplifiers and parametric amplifiers for which no provision exists elsewhere.

|  | H03G |
CONTROL OF AMPLIFICATION (impedance networks, e.g. attenuators, Fulltext... Hierarchy... Expanded...H03H; control of transmission in lines Fulltext... Hierarchy... Expanded...H04B 3/04)

|  | H03G |
Note(s) This sub-class deals with (a) control of gain of amplifiers or frequency-changers, (b) control of frequency range of amplifiers, and (c) limiting amplitude or rate of change of amplitude. Attention is drawn to the note following the title of sub-class Fulltext... Hierarchy... Expanded...H03F. [3]

|  | H03H |
IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (measuring, testing Fulltext... Hierarchy... Expanded...G01R; impedance networks or resonators consisting of distributed impedances, e.g. of the waveguide type, Fulltext... Hierarchy... Expanded...H01P; control of amplification, e.g. bandwidth control of amplifiers, Fulltext... Hierarchy... Expanded...H03G; tuning resonant circuits, e.g. tuning coupled resonant circuits, Fulltext... Hierarchy... Expanded...H03J; networks for modifying the frequency characteristics of communication systems Fulltext... Hierarchy... Expanded...H04B)

|  | H03H |
Note(s) This sub-class deals with (a) networks comprising lumped impedance elements, (b) networks comprising distributed impedance elements together with lumped impedance elements, (c) networks comprising electromechanical or electro-acoustic devices, (d) networks simulating reactances and comprising discharge tubes or semiconductor devices, and (e) constructions of electromechanical resonators. In this sub-class, the term "passive elements" refers to resistors, capacitors, inductors, mutual inductors, or diodes. [3] Main groups with a higher number take precedence. [3]

|  | H03J |
TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS (indicating arrangements for measuring Fulltext... Hierarchy... Expanded...G01D; measuring, testing Fulltext... Hierarchy... Expanded...G01R; remote-control in general Fulltext... Hierarchy... Expanded...G05, Fulltext... Hierarchy... Expanded...G08; automatic control or stabilisation of generators Fulltext... Hierarchy... Expanded...H03L)

|  | H03J |
Note(s) This sub-class also covers the control of tuning, including the combined control of tuning and other functions, e.g. combinations of tuning control and volume control, combinations of control of local oscillator and of supplementary resonant circuits. [3]

|  | H03K |
PULSE TECHNIQUE (measuring pulse characteristics Fulltext... Hierarchy... Expanded...G01R; mechanical counters having an electrical input Fulltext... Hierarchy... Expanded...G06M; information storage devices in general Fulltext... Hierarchy... Expanded...G11; sample-and-hold arrangements in electric analogue stores Fulltext... Hierarchy... Expanded...G11C 27/02; construction of switches involving contact making and breaking for generation of pulses, e.g. by using a moving magnet, Fulltext... Hierarchy... Expanded...H01H; static conversion of electric power Fulltext... Hierarchy... Expanded...H02M; generation of oscillations by circuits employing active elements which operate in a non-switching manner Fulltext... Hierarchy... Expanded...H03B; modulating sinusoidal oscillations with pulses Fulltext... Hierarchy... Expanded...H03C, Fulltext... Hierarchy... Expanded...H04L; discriminator circuits involving pulse counting Fulltext... Hierarchy... Expanded...H03D; automatic control of generators Fulltext... Hierarchy... Expanded...H03L; starting, synchronisation, or stabilisation of generators where the type of generator is irrelevant or unspecified Fulltext... Hierarchy... Expanded...H03L)

|  | H03K |
Note(s) This sub-class deals with (a) methods, circuits, devices, or apparatus using active elements operating in a discontinuous or switching manner for generating, counting, amplifying, shaping, modulating, demodulating, coding, decoding, or otherwise manipulating signals, (b) electronic switching not involving contact-making and braking, and (c) logic circuits handling electric pulses. In this sub-class, an "active element" is understood to exercise control over the conversion of input energy into an oscillation or a discontinuous flow of energy.

|  | H03L |
AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (of dynamo-electric generators Fulltext... Hierarchy... Expanded...H02P) [3]

|  | H03L |
Note(s) This sub-class includes automatic control circuits for generators of electronic oscillations or pulses and also includes starting, synchronisation, or stabilisation circuits for generators where the type of generator is irrelevant or unspecified. Stabilisation or starting circuits specially adapted to only one specific type of generator are classified with the generator in the relevant sub-group of sub-classes Fulltext... Hierarchy... Expanded...H03B, Fulltext... Hierarchy... Expanded...H03K. [3] The term "automatic control" includes only closed loop systems. [3]