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 G01R; generators adapted for electrophonic musical instruments G10H; synthesis of sound waves G10L; masers, lasers H01S; dynamo-electric machines H02K; power inverter circuits H02M; by using pulse techniques H03K; automatic control of generators H03L; starting, synchronisation or stabilisation of generators where the type of generator is irrelevant or unspecified H03L; generation of oscillations in plasma H05H)

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

Note(s)

  1. This sub-class deals only with modulation, keying, or interruption of sinusoidal oscillations or electromagnetic waves, the modulating signal having any desired waveform.
  2. 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 H01S; circuits capable of acting both as modulator and demodulator H03C; details applicable to both modulators and frequency-changers H03C; demodulating pulses H03K 9/00; transforming types of pulse modulation H03K 11/00; pulse code modulation H03K 13/00; repeater stations H04B 7/14; demodulators adapted for ac systems of digital-information transmission H04L 27/00; synchronous demodulators adapted for colour television 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 G01R; optical parametric amplifiers G02F; circuit arrangements with secondary emission tubes H01J 43/30; masers, lasers H01S; control of amplification H03G; coupling arrangements independent of the nature of the amplifier, voltage dividers H03H; amplifiers capable only of dealing with pulses H03K; repeater circuits in transmission lines H04B 3/36, H04B 3/58; application of speech amplifiers in telephonic communication H04M 1/60, 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, H03H; control of transmission in lines H04B 3/04)
 H03G

Note(s)

  1. 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.
  2. Attention is drawn to the note following the title of sub-class H03F[3]

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

Note(s)

  1. 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.
  2. In this sub-class, the term "passive elements" refers to resistors, capacitors, inductors, mutual inductors, or diodes. [3]
  3. Main groups with a higher number take precedence. [3]

 H03J
TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS (indicating arrangements for measuring G01D; measuring, testing G01R; remote-control in general G05, G08; automatic control or stabilisation of generators 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 G01R; mechanical counters having an electrical input G06M; information storage devices in general G11; sample-and-hold arrangements in electric analogue stores G11C 27/02; construction of switches involving contact making and breaking for generation of pulses, e.g. by using a moving magnet, H01H; static conversion of electric power H02M; generation of oscillations by circuits employing active elements which operate in a non-switching manner H03B; modulating sinusoidal oscillations with pulses H03C, H04L; discriminator circuits involving pulse counting H03D; automatic control of generators H03L; starting, synchronisation, or stabilisation of generators where the type of generator is irrelevant or unspecified H03L)
 H03K

Note(s)

  1. 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.
  2. 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 H02P)  [3]
 H03L

Note(s)

  1. 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 H03B, H03K[3]
  2. The term "automatic control" includes only closed loop systems. [3]