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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; coding, decoding or code conversion, in general H03M; repeater stations H04B 7/14; demodulators adapted for ac systems of digital information transmission H04L 27/00; synchronous demodulators adapted for colour television H04N 9/66)
Definition statement
This subclass/group covers:

Demodulation or transference of signals modulated on a sinusoidal carrier or on electromagnetic waves.

Relationship between large subject matter areas

The modulation and demodulation of pulse trains, for example in Pulse Width Modulation circuits, is covered in subclass H03K.

System aspects of modulation by digital signals of the frequency, phase or amplitude of a sinusoidal carrier, or carriers, for example in quadrature (I-Q) modulation systems, and the demodulation thereof, is covered in subclass H04L.

Analogue quadrature modulation used in the NTSC and PAL colour television systems (where the I and Q signals representing colour difference values are substantially continuously variable), and the demodulation of these signals, is covered in H04N.

The modulation of sinusoidal signals, for example in AM and FM broadcasting, is covered in sub class H03C.

References relevant to classification in this subclass
This subclass/group does not cover:
Masers, lasers
Circuits capable of acting both as modulator and demodulator;balanced modulators
Details applicable to both modulators and frequency changers
Demodulating pulses which have been modulated with a continuously variable signal
Transforming types of pulse modulation
Relay systems, e.g. repeater stations
Demodulators adapted for digitally modulated-carrier systems
Synchronous demodulators adapted for colour television
Phase locked loops; phase comparators therein
Informative references
Attention is drawn to the following places, which may be of interest for search:
Coding, decoding or code conversion, in general
Further details of receivers within transmission systems
Further circuits for superheterodyne receivers within transmission systems
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Homodyne, synchrodyne or zero-IF receiver
A receiver in which the local oscillator (LO) frequency is set to the same frequency as the received RF carrier frequency resulting in direct conversion of the received signal to a baseband (or zero IF) frequency for information recovery. In a near-zero IF receiver, the LO frequency is set very close to the carrier frequency of the RF signal.
Superheterodyne receiver
A receiver in which a received RF signal is converted to an intermediate frequency (IF) by at least one stage of frequency conversion (e.g. a ‘mixer’ stage which forms the product of the RF signal and a local oscillator signal)
Synonyms and Keywords

In patent documents the following abbreviations are often used:

Superhet
A superheterodyne receiver
Double (multiple) superhet
A double-conversion receiver using two intermediate frequencies, i.e. a superhet receiver in which a received RF signal passes through two (or more) successive stages of frequency conversion to different intermediate frequencies, one of which may be zero-IF or baseband.
Demodulation of amplitude-modulated oscillations (H03D 5/00, H03D 9/00, H03D 11/00 take precedence)
Definition statement
This subclass/group covers:

Demodulation of signals being amplitude-modulated on a sinusoidal carrier.

References relevant to classification in this group
This subclass/group does not cover:
Circuits for demodulating amplitude-modulated or angle-modulated oscillations at will
Demodulation or transference of modulation of modulated electromagnetic waves
Super-regenerative demodulator circuits
Amplitude demodulators adapted for digitally modulated-carrier systems, e.g. using on-off keying; Single sideband orvestigial sideband modulation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Homodyne or synchrodyne single sideband receivers
Special rules of classification within this group

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 subclass/group, the following terms (or expressions) are used with the meaning indicated:
IP2
Second Order Intercept Point
IM2
Second order intermodulation product
Modifications of demodulators to reduce interference by undesired signals
Definition statement
This subclass/group covers:

Example:

media0.jpg

WO2011047703

IM2 reduction e.g. by summing RF signal to LO

by means of non-linear two-pole elements (H03D 1/22, H03D 1/26, H03D 1/28 take precedence)
References relevant to classification in this subgroup
This subclass/group does not cover:
Homodyne or synchrodyne circuits
Demodulation of amplitude-modulated oscillations by means of transit-time tubes
Demodulation of amplitude-modulated oscillations by deflecting an electron beam in a discharge tube
by means of non-linear elements having more than two poles (H03D 1/22, H03D 1/26, H03D 1/28 take precedence)
References relevant to classification in this subgroup
This subclass/group does not cover:
Homodyne or synchrodyne circuits
Demodulation of amplitude-modulated oscillations by means of transit-time tubes
Demodulation of amplitude-modulated oscillations by deflecting an electron beam in a discharge tube
of semiconductor devices
Definition statement
This subclass/group covers:

Example:

media1.jpg

US2009015295

Amplitude demodulation using e.g. MOS transistors

Homodyne or synchrodyne circuits { (receiver circuits H04B 1/30) }
Definition statement
This subclass/group covers:

Example:

media2.jpg

EP2315350

Demodulation using two quadrature channels (20b) and a PLL (12) in a synchronous circuit. (Analog/digital converter 6, decimation filter 8, Hilbert filter 10; elements 14, 16, 18, 20, 22 are not relevant for the demodulation principle)

Informative references
Attention is drawn to the following places, which may be of interest for search:
Homodyne or synchrodyne receiver circuits
{using switches for the decoding (diodes used as switches H03D 1/2218) }
Informative references
Attention is drawn to the following places, which may be of interest for search:
Diodes used as switches
{using two quadrature channels (H03D 1/2209 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Decoders for simultaneous demodulation and decoding of signals composed of a sum-signal and a suppressed carrier, amplitude modulated by a difference signal
{and a phase locked loop}
Informative references
Attention is drawn to the following places, which may be of interest for search:
Mean frequency regulation of modulators using a phase locked loop
{using FET`s (H03D 1/2209, H03D 1/2245 and H03D 1/2281 take precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Decoders for simultaneous demodulation and decoding of signals composed of a sum-signal and a suppressed carrier, amplitude modulated by a difference signal
Using two quadrature channels
Using a phase locked loop
for demodulation of signals wherein one sideband or the carrier has been wholly or partially suppressed { (receiver circuits H04B 1/302) }
Informative references
Attention is drawn to the following places, which may be of interest for search:
Receiver circuits
by deflecting an electron beam in a discharge tube (H03D 1/26 takes precedence)
References relevant to classification in this subgroup
This subclass/group does not cover:
Demodulation of amplitude-modulated oscillations by means of transit-time tubes
Demodulation of angle-, {frequency- or phase-} modulated oscillations (H03D 5/00, H03D 9/00, H03D 11/00 take precedence)
Definition statement
This subclass/group covers:

Demodulation of angle-, frequency- or phase- modulated oscillations.

Example:

media3.jpg

EP1163719

FM demodulation by conversion into two quadrature related signals

References relevant to classification in this group
This subclass/group does not cover:
Circuits for demodulating amplitude-modulated or angle-modulated oscillations at will
Demodulation or transference of modulation of modulated electromagnetic waves
Super-regenerative demodulator circuits
Frequency demodulators adapted for digitally modulated-carrier systems, i.e. using frequency-shift keying
Phase demodulators adapted for digitally modulated-carrier systems, i.e. using phase-shift keying
Informative references
Attention is drawn to the following places, which may be of interest for search:
Arrangements for measuring frequencies; Arrangements for analyzing frequency spectra
Automatic bandwidth control
Muting in frequency-modulation receivers
Arrangements for limiting amplitude
Automatic frequency regulation in receivers
Automatic frequency control
Phase-locked loops in general
Phase-locked loops including two phase detectors in general
H03L7/87
Phase-locked loops using a controlled phase shifter in general
Multiple phase locked loops in general
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
I/Q
in-phase, quadrature
{Details of arrangements applicable to more than one type of frequency demodulator (H03D 3/28 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Modifications of demodulators to reduce effects of temperature variations
{Modifications of demodulators to reduce interference by undesired signals (H03D 3/248 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Angle demodulation by detecting phase difference between two signals obtained from input signal including locked-in oscillation circuits to reject or remove amplitude variations with means for eliminating interfering signals, e.g. by multiple phase locked loops
{Arrangements for reducing frequency deviation, e.g. by negative frequency feedback (combined with a phase locked loop demodulator H03D 3/242; changing frequency deviation for modulators H03C 3/06) }
Informative references
Attention is drawn to the following places, which may be of interest for search:
Changing frequency deviation for modulators
Angle demodulation by detecting phase difference between two signals obtained from input signal including locked-in oscillation circuits to reject or remove amplitude variations combined with a phase locked loop demodulator
{wherein the demodulated signal is used for controlling a bandpass filter (automatic bandwidth control H03G; automatic frequency control H03J 7/02) }
Informative references
Attention is drawn to the following places, which may be of interest for search:
Automatic bandwidth control
Automatic frequency control
{by sampling the oscillations and further processing the samples, e.g. by computing techniques (H03D 3/007 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Angle demodulation by converting the oscillations into two quadrature related signals
{by converting the oscillations into two quadrature related signals (H03D 3/245 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Angle demodulation by detecting phase difference between two signals obtained from input signal including locked-in oscillation circuits to reject or remove amplitude variations using at least two phase detectors in the loop
by detecting phase difference between two signals obtained from input signal (H03D 3/28 to H03D 3/32 take precedence; {muting in frequency-modulation receivers H03G 3/28} ; limiting arrangements H03G 11/00)
Definition statement
This subclass/group covers:

Example:

media4.jpg

EP1040565

Phase demodulation by mixing of two signals obtained from input signal. A phase shifter network (504) provides a phase shift of 90° at the center frequency.

References relevant to classification in this subgroup
This subclass/group does not cover:
Modifications of demodulators to reduce effects of temperature variations
Angle demodulation by means of transit-time tubes
Angle demodulation by deflecting an electron beam in a discharge tube
Informative references
Attention is drawn to the following places, which may be of interest for search:
Muting in frequency-modulation receivers
Limiting arrangements
by counting or integrating cycles of oscillations {arrangements for measuring frequencies G01R 23/10}
Informative references
Attention is drawn to the following places, which may be of interest for search:
Arrangements for measuring frequencies
{using at least twophase detectors in the loop (H03D 3/244 takes precedence; in general H03L 7/087) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Angle demodulation by detecting phase difference between two signals obtained from input signal including locked-in oscillation circuits to reject or remove amplitude variations combined with means for obtaining automatic gain control
Informative references
Attention is drawn to the following places, which may be of interest for search:
PLLs using at least two phase detectors in the loop in general
{using a controlled phase shifter (in general H03L 7/081) }
Informative references
Attention is drawn to the following places, which may be of interest for search:
PLLs provided with an additional controlled phase shifter in general
{with means for eliminating interfering signals, e.g. by multiple phase locked loops (multiple loops in general H03L 7/07, H03L 7/22) }
Informative references
Attention is drawn to the following places, which may be of interest for search:
PLLs with multiple loops in general
by means of sloping amplitude/frequency characteristic of tuned or reactive circuit (H03D 3/28 to H03D 3/32 takes precedence)
Definition statement
This subclass/group covers:

Example:

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US2006226897

FM demodulation by is conversion to an amplitude modulated output signal (VO)

References relevant to classification in this subgroup
This subclass/group does not cover:
Modifications of demodulators to reduce effects of temperature variations
Angle demodulation by means of transit-time tubes
Angle demodulation by deflecting an electron beam in a discharge tube
Modifications of demodulators to reduce effects of temperature variations ( {automatic frequency regulation in receivers H03J} ; automatic frequency control H03L)
Informative references
Attention is drawn to the following places, which may be of interest for search:
Automatic frequency regulation in receivers
Automatic frequency control
by deflecting an electron beam in a discharge tube (H03D 3/30 takes precedence)
References relevant to classification in this subgroup
This subclass/group does not cover:
Demodulation of angle-modulated oscillations by means of transit-time tubes
by means of electromechanical devices (H03D 3/16 takes precedence)
Definition statement
This subclass/group covers:

FM Demodulation by means of electromechanical devices such as FBARs or piezoelectric resonators.

References relevant to classification in this subgroup
This subclass/group does not cover:
Demodulation of angle-modulated oscillations by detecting phase difference between two signals obtained from input signal by combining signals additively or in product demodulators by means of electromechanical resonators
Circuits for demodulating amplitude-modulated or angle-modulated oscillations at will (H03D 9/00, H03D 11/00 take precedence)
Definition statement
This subclass/group covers:

Circuits selectable between FM and AM demodulation

Polar or phase-amplitude demodulation

Example:

media7.jpg

US2007178866

Demodulator switchable between AM demodulation

media8.jpg

WO2007005139

Phase-amplitude-phase demodulation

References relevant to classification in this group
This subclass/group does not cover:
Demodulation or transference of modulation of modulatedelectromagnetic waves
Super-regenerative demodulator circuits
Demodulators adapted for digitally modulated-carrier systems characterised by combinations of amplitude and angle modulation, e.g. quadrature-amplitude modulated carrier systems
Informative references
Attention is drawn to the following places, which may be of interest for search:
Polar or phase-amplitude modulation
Transference of modulation from one carrier to another, e.g. frequency-changing (H03D 9/00, H03D 11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F)
Definition statement
This subclass/group covers:

Mixer circuits in general, applicable to both transmitters or receivers.

References relevant to classification in this group
This subclass/group does not cover:
Demodulation or transference of modulation of modulated electromagnetic waves
Super-regenerative demodulator circuits
Dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F
Informative references
Attention is drawn to the following places, which may be of interest for search:
Arrangements for performing computing operations, multiplication or division
by means of diodes (H03D 7/14 to H03D 7/22 take precedence)
References relevant to classification in this subgroup
This subclass/group does not cover:
Balanced arrangements
Multiple-frequency-changing
Modifications of frequency-changers for eliminating image frequencies
By means of transit-time tubes
By deflecting an electron beam in a discharge tube
by means of discharge tubes having more than two electrodes (H03D 7/14 to H03D 7/22 take precedence)
References relevant to classification in this group
This subclass/group does not cover:
Balanced arrangements
Multiple-frequency-changing
Modifications of frequency-changers for eliminating image frequencies
By means of transit-time tubes
By deflecting an electron beam in a discharge tube
by means of semiconductor devices having more than two electrodes (H03D 7/14 to H03D 7/22 take precedence)
References relevant to classification in this subgroup
This subclass/group does not cover:
Balanced arrangements
Multiple-frequency-changing
Modifications of frequency-changers for eliminating image frequencies
By means of transit-time tubes
By deflecting an electron beam in a discharge tube
Balanced arrangements
Definition statement
This subclass/group covers:

Example:

media9.jpg

DE102010002575

Balanced active mixer arrangement (Gilbert type)

{ with transistors}
References relevant to classification in this subgroup
This subclass/group does not cover:
Balanced arrangements using a combination of bipolar transistors and field-effect transistors
H03D7/14E
{ using field-effect transistors (H03D 7/145 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Balanced arrangements using a combination of bipolar transistors and field-effect transistors
H03D7/14E
Multiple-frequency-changing
Definition statement
This subclass/group covers:

Examples:

media10.jpg

US2001007151

Dual conversion receiver using two frequency changers being connected in cascade

media11.jpg

EP2363952

Balanced passive mixer arrangement with two frequency changers located in different paths

References relevant to classification in this subgroup
This subclass/group does not cover:
Circuits for superheterodyne receivers on system level
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Q/I
quadrature / in-phase
{at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature (combined with amplitude demodulation H03D 1/2245, combined with angle demodulation H03D 3/007; N-path filters H03H 19/002) }
Informative references
Attention is drawn to the following places, which may be of interest for search:
Homodyne or synchrodyne circuits for amplitude demodulation using two quadrature channels
Angle demodulation by converting the oscillations into two quadrature related signals
N-path filters
Modifications of frequency-changers for eliminating image frequencies { (H03D 7/16 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Multiple-frequency-changing
by deflecting an electron beam in a discharge tube (H03D 7/20 takes precedence)
Definition statement
This subclass/group covers:

Example:

media12.jpg

US2623167:

Mixing of a signal ("carrier") frequency with a local oscillator frequency to obtainan intermediate frequency by means of a discharge tube.

References relevant to classification in this subgroup
This subclass/group does not cover:
Transference of modulation by means of transit-time tubes
Demodulation or transference of modulation of modulated electromagnetic waves (demodulating light, transferring modulation in light waves G02F 2/00)
Definition statement
This subclass/group covers:
  • Demodulation using distributed inductance and capacitance H03D 9/02
  • Transference of modulation using distributed inductance and capacitance H03D 9/06
References relevant to classification in this subgroup
This subclass/group does not cover:
Devices or arrangements for demodulating light transferring the modulation of modulated light or for changing the frequency of light

Further classification information:

Demodulation using distributed inductance and capacitance, e.g. in feeder lines
Definition statement
This subclass/group covers:

Example:

media13.jpg
media14.jpg

GB2128827

Demodulation using a microwave detector including a transmission line (11) as distributed inductance

Transference of modulation using distributed inductance and capacitance
Definition statement
This subclass/group covers:

Example:

media15.jpg

WO2009054095

Transference of modulation using a mixer based on diodes and microstrip lines (51, 54) as distributed inductances

{mounted in a hollow waveguide (H03D 9/0641 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Diodes mounted on a stripline circuit located in a hollow waveguide
{using bipolar transistors (H03D 9/0683 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Using a combination of bipolar transistors and field effect transistors
{using field effect transistors (H03D 9/0683 takes precedence) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Using a combination of bipolar transistors and field effect transistors
Super-regenerative demodulator circuits {applications in responders G01S}
Definition statement
This subclass/group covers:

Super-regenerative demodulator circuits for amplitude modulation H03D 11/02

Super-regenerative demodulator circuits for angle modulation H03D 11/06

Informative references
Attention is drawn to the following places, which may be of interest for search:
Applications in responders
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Regenerative receiver; Super-regenerative receiver
A regenerative receiver is a receiver that uses feedback around an active device in a bandpass circuit, causing it to operate on the verge of oscillation. The active device may then provide high amplification of an RF signal in a receiver circuit that needs few components. In a super-regenerative receiver, the oscillation grows at the desired RF frequency and a lower frequency oscillation (within the same stage or from a second oscillator stage) periodically interrupts or "quenches" the main RF oscillation. This may occur at an ultrasonic rate.
by means of semiconductor devices having more than two electrodes
Definition statement
This subclass/group covers:

Example:

media16.jpg

GB2343571

Super regenerative demodulator

Circuits for comparing the phase or frequency of two mutually-independant oscillations { (measuring phase G01R 25/00; phase-discriminators with yes/no output G01R 25/005) }
Definition statement
This subclass/group covers:

Phase or frequency comparators

  • in which a pulse counter is used followed by a conversion into an analog signal H03D 13/001
  • in which both oscillations are converted by logic means into pulses which
  • are applied to filtering or integrating means H03D 13/003
  • in which one of the oscillations is, or is converted into, a signal having a special waveform, e.g. triangular H03D 13/005
  • by analog multiplication of the oscillations or by performing a similar analog operation on the oscillations H03D 13/007

Example:

media17.jpg
media18.jpg

US2008122491

Frequency comparator in which one signal (S1) is converted into a triangular waveform (Sw1) and compared with an internal oscillation (S2)

References relevant to classification in this group
This subclass/group does not cover:
Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
Phase-discriminators with yes/no output
Informative references
Attention is drawn to the following places, which may be of interest for search:
Phase locked loops; frequency or phase detectors or comparators therein
Subject matter not provided for in other groups of this subclass
Definition statement
This subclass/group covers:

Demodulation or transference of signals modulated on a sinusoidal carrier or on electromagnetic waves that does not comply with other groups of this subclass.

References relevant to classification in this group
This subclass/group does not cover:
Demodulation of amplitude-modulated oscillations
Demodulation of angle-, frequency-or phase- modulated oscillations
Circuits for demodulating amplitude-modulated or angle-modulated oscillations at will
Transference of modulation from one carrier to another, e.g. frequency-changing
Demodulation or transference of modulation of modulated electromagnetic waves
Super-regenerative demodulator circuits by means of semiconductor devices having more than two electrodes
Circuits for comparing the phase or frequency of two mutually-independent oscillations
Indexing scheme relating to details of demodulation or transference of modulation from one carrier to another covered by H03D
Definition statement
This subclass/group covers:

Particular circuit elements of demodulators H03D200/01

Functional aspects of demodulators H03D200/02

Quadrature arrangements
References relevant to classification in this group
This subclass/group does not cover:
Homodyne or synchrodyne circuits for amplitude demodulation using quadrature channels
Angle demodulation by converting the oscillations into two quadrature related signals
Multiple frequency changing with at least two frequency changers being located in different paths
This page is owned by Office of Patent Classification.
Last Modified: 10/11/2013