CPC Definition - Subclass H03C

Last Updated Version: 2019.05
MODULATION (measuring, testing G01R; masers, lasers H01S; modulators specially adapted for use in the amplifiers H03F 3/38; modulating pulses H03K 7/00; so-called modulators capable only of a switching between predetermined states of amplitude, frequency or phase H03K 17/00, H04L; coding, decoding or code conversion, in general H03M; synchronous modulators specially adapted for colour television H04N 9/65)
Definition statement

This place covers:

  • Modulation, keying, or interruption of sinusoidal oscillations or electromagnetic waves, the modulating signal having any desired waveform.
  • Amplitude modulation
  • Angle modulation
  • Amplitude and angle modulation produced simultaneously or at will by the same modulating signal
  • Modulating electromagnetic waves

In this subclass, modulation is a process of applying information onto a sinusoidal carrier.

Relationships with other classification places

Transference of modulation from one carrier to the other and frequency changing is classified in H03D 7/00. Frequency changers used to convert from baseband may, where appropriate, additionally be classified in H03C.

H03C is used to classify modulators essentially at circuit level, e.g. transistor level. Higher level aspects, e.g. transmitters or transmission systems, particularly where the modulator type is only a black box or of a standard configuration, are generally classified in H04B, H04L or with the specific application.

References
Limiting references

This place does not cover:

Measuring, testing

G01R

Modulating light

G02F 1/00

Masers, lasers

H01S

Modulators specially adapted for use in dc amplifiers

H03F 3/38

Modulating non-sinusoidal oscillations

H03K, H04L

Modulating pulses

H03K 7/00

So-called modulators capable only of switching between predetermined states of amplitude, frequency or phase

H03K 17/00, H04L

Coding, decoding or code conversion, in general

H03M

Transmission of data signals, monitoring and testing arrangements and suppression of noise and interference

H04B

AC transmission systems

H04L 27/00

Synchronous modulators specially adapted for colour television

H04N 9/65

Special rules of classification
  • Circuits usable both as modulator and demodulator are classified in H03C.
  • Quite frequently, an exclusive group assignment of documents to amplitude modulation (H03C 1/00) or angle modulation (H03C 3/00) is not feasible (and/or not given within the document). In these cases, the best match with a subgroup definition in either or both groups is decisive.
  • Cases concerning a type of modulation that effects neither amplitude nor angle modulation, e.g. waveform modulation, should be classified in H03C 99/00.
Amplitude modulation (H03C 5/00, H03C 7/00 take precedence)
Definition statement

This place covers:

Circuits and methods usable for modulation of a sinusoidal electromagnetic carrier wave whereby its amplitude is modified according to a modulating signal with frequency lower than that of the carrier. The modulating signal can be digital, resulting e.g. in Amplitude Shift Keying, or analog (see the example below).

Example:

media0.png

Waveform of amplitude modulated carrier wave.

Relationships with other classification places

While modulators modulating the angle as well as the amplitude of a signal are classified in H03C 5/00, aspects of the amplitude modulation may still be classified in H03C 1/00.

References
Limiting references

This place does not cover:

Amplitude modulation and angle modulation produced simultaneously or at will by the same modulating signal

H03C 5/00

Modulating electromagnetic waves

H03C 7/00

Mixers per se

H03D 7/00

Pulse amplitude modulation

H03K 7/02

Informative references

Attention is drawn to the following places, which may be of interest for search:

Balanced modulators/mixers

H03D 7/1425, H03D 7/1441, H03D 7/14

Amplifiers

H03F

Summing of phase-modulated signals

H03F 1/0294

Automatic control of gain

H03G

Transmitters and details of transmission

H04B 1/00

AC transmission systems including amplitude modulation circuits

H04L 27/02, H04L 27/04

Special rules of classification

Documents should in general be classified in all subgroups which apply, e.g. a single sideband modulator may, in addition to H03C 1/60, be classified in H03C 1/36, if it is a transistor type.

Glossary of terms

In this place, the following terms or expressions are used with the meaning indicated:

by means of

The actual amplitude modulation is performed by these "means". It does not mean that such "means" are merely present in the circuit but fulfilling another purpose.

Synonyms and Keywords

In patent documents, the following abbreviations are often used:

AM

Amplitude Modulation

SSB

single side band

by means of variable impedance element (H03C 1/28 - H03C 1/34, H03C 1/46 - H03C 1/52, H03C 1/62 take precedence)
References
Limiting references

This place does not cover:

Amplitude Modulation by means of transit-time tube

H03C 1/28

Amplitude Modulation by means of a magnetron

H03C 1/30

Amplitude Modulation by deflection of electron beam in discharge tube

H03C 1/32

Amplitude Modulation by means of light-sensitive element

H03C 1/34

Amplitude Modulators with mechanically or acoustically driven parts

H03C 1/46

Amplitude Modulation by means of Hall-effect devices

H03C 1/48

Amplitude Modulation by converting angle modulation to amplitude modulation

H03C 1/50

Amplitude Modulators in which carrier or one side-band are wholly or partially suppressed

H03C 1/52

Amplitude Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present

H03C 1/62

by means of discharge device having at least three electrodes (H03C 1/28 - H03C 1/34, H03C 1/50, H03C 1/52, H03C 1/62 take precedence)
References
Limiting references

This place does not cover:

Amplitude Modulation by means of transit-time tube

H03C 1/28

Amplitude Modulation by means of a magnetron

H03C 1/30

Amplitude Modulation by deflection of electron beam in discharge tube

H03C 1/32

Amplitude Modulation by means of light-sensitive element

H03C 1/34

Amplitude Modulation by converting angle modulation to amplitude modulation

H03C 1/50

Amplitude Modulators in which carrier or one side-band are wholly or partially suppressed

H03C 1/52

Amplitude Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present

H03C 1/62

by means of semiconductor device having at least three electrodes (H03C 1/34, H03C 1/50, H03C 1/52, H03C 1/62 take precedence)
References
Limiting references

This place does not cover:

Amplitude Modulation by means of light-sensitive element

H03C 1/34

Amplitude Modulation by converting angle modulation to amplitude modulation

H03C 1/50

Amplitude Modulators in which carrier or one side-band are wholly or partially suppressed

H03C 1/52

Amplitude Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present

H03C 1/62

by converting angle modulation to amplitude modulation (H03C 1/28 - H03C 1/34, H03C 1/46, H03C 1/48 take precedence)
Definition statement

This place covers:

Example:

media1.jpg

US2007040606

Conversion of angle modulation (212) in amplitude modulation (228).

References
Limiting references

This place does not cover:

Amplitude Modulation by means of transit-time tube

H03C 1/28

Amplitude Modulation by means of a magnetron

H03C 1/30

Amplitude Modulation by deflection of electron beam in discharge tube

H03C 1/32

Amplitude Modulation by means of light-sensitive element

H03C 1/34

Amplitude Modulators with mechanically or acoustically driven parts

H03C 1/46

Amplitude Modulation by means of Hall-effect devices

H03C 1/48

Modulators in which carrier or one side-band are wholly or partially suppressed (H03C 1/28 - H03C 1/34, H03C 1/46, H03C 1/48 take precedence)
References
Limiting references

This place does not cover:

Amplitude Modulation by means of transit-time tube

H03C 1/28

Amplitude Modulation by means of a magnetron

H03C 1/30

Amplitude Modulation by deflection of electron beam in discharge tube

H03C 1/32

Amplitude Modulation by means of light-sensitive element

H03C 1/34

Amplitude Modulators with mechanically or acoustically driven parts

H03C 1/46

Amplitude Modulation by means of Hall-effect devices

H03C 1/48

{using field-effect transistors}
Definition statement

This place covers:

Example:

media2.png

EP1338085

Carrier suppression in a double balanced modulator using field effect transistors.

Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present (H03C 1/28 - H03C 1/34, H03C 1/46, H03C 1/48 take precedence)
References
Limiting references

This place does not cover:

Amplitude Modulation by means of transit-time tube

H03C 1/28

Amplitude Modulation by means of a magnetron

H03C 1/30

Amplitude Modulation by deflection of electron beam in discharge tube

H03C 1/32

Amplitude Modulation by means of light-sensitive element

H03C 1/34

Amplitude Modulators with mechanically or acoustically driven parts

H03C 1/46

Amplitude Modulation by means of Hall-effect devices

H03C 1/48

Angle modulation (H03C 5/00, H03C 7/00 take precedence)
Definition statement

This place covers:

  • Circuits and methods usable for angle, i.e. frequency and/or phase modulation.
Relationships with other classification places

While modulators modulating the angle as well as the amplitude of a signal are classified in H03C 5/00, aspects of the angle modulation may still be classified in H03C 3/00.

References
Limiting references

This place does not cover:

Amplitude modulation and angle modulation produced simultaneously or at will by the same modulating signal

H03C 5/00

Modulating electromagnetic waves

H03C 7/00

Frequency tuning of oscillators

H03B

Tuning of resonant circuits

H03J

Pulse/frequency modulators

H03K 7/04, H03K 7/06

Informative references

Attention is drawn to the following places, which may be of interest for search:

Oscillators, VCO

H03B

Mixers per se

H03D 7/00

Reduction of nonlinear distortion in amplifiers (particularly regarding H03C 3/406 and H03C 5/00

H03F 1/32

PLLs and other frequency regulation arrangements in general

H03L 7/00

PLL with fractional dividers

H03L 7/1974

Transmitters and details of transmission

H04B 1/00

AC transmission systems including phase or frequency modulation circuits

H04L 27/10, H04L 27/12, H04L 27/18, H04L 27/20

Glossary of terms

In this place, the following terms or expressions are used with the meaning indicated:

FM

Frequency Modulation

PLL

Phase Locked Loop

VCO

Voltage Controlled Oscillator

"by means of" in the subgroup definition

see explanation in H03C 1/00

Means for changing frequency deviation {(for demodulation H03D 3/003, H03D 3/242)}
Definition statement

This place covers:

Means for modifying the frequency modulation characteristics, e.g. the frequency range or bandwidth or the sensitivity of frequency deviation with respect to the modulating signal.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Reducing frequency deviation for demodulation

H03D 3/003, H03D 3/242

Modifications of modulator for regulating the mean frequency
Definition statement

This place covers:

Modifications of angle modulators for regulating the mean frequency of the carrier wave

Example:

media3.jpg

US5331293

Regulation of mean frequency in a modulator without PLL, using a demodulator in the feedback path

{using a phase locked loop}
Definition statement

This place covers:

media4.png

Schematic view of a PLL including a reference clock (LO), a phase detector, a loop filter, a voltage controlled oscillator (VCO) and a divider. The arrows point to subgroups assigned to manners of modulation.

Example:

media5.jpg

US2007093217

Regulation of mean frequency in a modulator with PLL, using three point modulation (H03C 3/0941) in divider (H03C 3/0925), reference clock (H03C 3/0966) and in front of the VCO (H03C 3/095) and at a mixer (H03C 3/0983).

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

PLL with frequency divider/counter in general

H03L 7/18

{using fractional frequency division in the feedback loop of the phase locked loop}
References
Limiting references

This place does not cover:

PLL synthesisers with fractional dividers

H03L 7/1974

by means of variable impedance (H03C 3/30 - H03C 3/38 take precedence)
Definition statement

This place covers:

Circuits or methods using an element with variable impedance for angle modulation.

References
Limiting references

This place does not cover:

Angle modulation by means of transit-time tube

H03C 3/30

Angle modulation the tube being a magnetron

H03C 3/32

Angle modulation by deflection of electron beam in discharge tube

H03C 3/34

Angle modulation by means of light-sensitive element

H03C 3/36

Conversion of amplitude to angle modulation

H03C 3/38

{using bipolar transistors (H03C 3/227 takes precedence)}
References
Limiting references

This place does not cover:

Using a combination of bipolar transistors and field effect transistors

H03C 3/227

{using field effect transistors (H03C 3/227 takes precedence)}
References
Limiting references

This place does not cover:

Using a combination of bipolar transistors and field effect transistors

H03C 3/227

{using two quadrature frequency conversion stages in cascade}
Definition statement

This place covers:

Example:

media6.jpg

US2003095608

Conversion of amplitude to angle modulation by using two quadrature frequency conversion stages in cascade (4, 5 and 11, 12)

by means of electromechanical devices (H03C 3/28 takes precedence)
References
Limiting references

This place does not cover:

Angle modulation using variable impedance driven mechanically or acoustically

H03C 3/28

Amplitude modulation and angle modulation produced simultaneously or at will by the same modulating signal (H03C 7/00 takes precedence)
Definition statement

This place covers:

  • Circuits selectable between FM and AM modulation
  • Polar or phase-amplitude modulation by means of transistor circuits
  • Polar or phase-amplitude modulation by means of transit time tubes

Example:

media7.png

EP2034686

Polar modulation resulting in simultaneous amplitude and phase modulation.

References
Limiting references

This place does not cover:

Conversion of angle to amplitude modulation

H03C 1/50

Conversion of amplitude to angle modulation

H03C 3/38

Modulating electromagnetic waves

H03C 7/00

Glossary of terms

In this place, the following terms or expressions are used with the meaning indicated:

"by the same modulating signal"

also includes the common case where the modulation signal is split into two components

Modulating electromagnetic waves (modulating light G02F 1/00; for generating oscillations H03B, H03K)
Definition statement

This place covers:

Modulation of electromagnetic waves, e.g. microwaves

  • in transmission line, waveguide, cavity resonator or radiation field of aerial H03C 7/02
References
Limiting references

This place does not cover:

Modulating light

G02F 1/00

Informative references

Attention is drawn to the following places, which may be of interest for search:

For generating oscillations H03B

H03B; H03K

{using semiconductor devices}
Definition statement

This place covers:

Example:

media8.png

EP0463665

Microwave modulator using transmission line (2), vector modulator (4) and quadrature detector (6).

Polarisation of transmitted wave being modulated {(H03C 7/022 takes precedence)}
References
Limiting references

This place does not cover:

Using ferromagnetic devices, e.g. ferrites

H03C 7/022

Subject matter not provided for in other groups of this subclass
Definition statement

This place covers:

Modulation, keying, or interruption of sinusoidal oscillations or electromagnetic waves that does not comply with other groups of this subclass.

References
Limiting references

This place does not cover:

Amplitude modulation

H03C 1/00

Angle modulation

H03C 3/00

Amplitude modulation and angle modulation produced simultaneously or at will by the same modulating signal

H03C 5/00

Modulating electromagnetic waves

H03C 7/00

Indexing scheme relating to details of modulators or modulation methods covered by H03C
Definition statement

This place covers:

Particular circuit elements of modulators H03C200/01

Functional aspects of modulators H03C200/02

Filters with particular characteristics
References
Limiting references

This place does not cover:

Filtering of the input modulating signal for obtaining a constant sensitivity of frequency modulation

H03C 2200/0054

Gilbert multipliers
References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Balanced arrangements for transference of modulation from one carrier to another

H03D 7/14

with one sideband wholly or partially suppressed
References
Limiting references

This place does not cover:

Amplitude modulators in which one side-band is wholly or partially suppressed

H03C 1/60

Measures to linearise modulation or reduce distortion of modulation characteristics
References
Limiting references

This place does not cover:

Modification of amplitude modulators to reduce distorsion

H03C 1/06

Modification of angle modulators to linearise modulation

H03C 3/08