IPC 6 English version H03D !A-H03D 13/00

H03D-H03D01300

SECTION H– ELECTRICITY

H 03

BASIC ELECTRONIC CIRCUITRY

H 03 D

DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER (masers, lasers H 01 S; circuits capable of acting both as modulator and demodulator H 03 C; details applicable to both modulators and frequency-changers H 03 C; demodulating pulses H 03 K 9/00; transforming types of pulse modulation H 03 K 11/00; coding, decoding or code conversion, in general H 03 M; repeater stations H 04 B 7/14; demodulators adapted for ac systems of digital-information transmission H 04 L 27/00; synchronous demodulators adapted for colour television H 04 N 9/66)

Note

This subclass covers only:

–

demodulation or transference of signals modulated on a sinusoidal carrier or on electromagnetic waves;

–

comparing phase or frequency of two mutually-independent oscillations.

Demodulation of amplitude-modulated oscillations (H 03 D 5/00, H 03 D 9/00, H 03 D 11/00 take precedence)

Details

Modifications of demodulators to reduce interference by undesired signals

Modifications of demodulators to reduce distortion, e.g. by negative feedback

by means of non-linear two-pole elements (H 03 D 1/22, H 03 D 1/26, H 03 D 1/28 take precedence)

of diodes

with provision for equalising ac and dc loads

by means of non-linear elements having more than two poles (H 03 D 1/22, H 03 D 1/26, H 03 D 1/28 take precedence)

of discharge tubes

of semiconductor devices

with provision for preventing undesired type of demodulation, e.g. preventing anode detection in a grid detection circuit

Homodyne or synchrodyne circuits

for demodulation of signals wherein one sideband or the carrier has been wholly or partially suppressed

by means of transit-time tubes

by deflecting an electron beam in a discharge tube (H 03 D 1/26 takes precedence)

Demodulation of angle-modulated oscillations (H 03 D 5/00, H 03 D 9/00, H 03 D 11/00 take precedence)

by detecting phase difference between two signals obtained from input signal (H 03 D 3/28 to H 03 D 3/32 take precedence; limiting arrangements H 03 G 11/00)

by counting or integrating cycles of oscillations

by combining signals additively or in product demodulators

by means of diodes, e.g. Foster-Seeley discriminator

in which the diodes are simultaneously conducting during the same half period of the signal, e.g. ratio detector

by means of discharge tubes having more than two electrodes

by means of semiconductor devices having more than two electrodes

by means of electromechanical resonators

by means of synchronous gating arrangements

producing pulses whose amplitude or duration depends on the phase difference

by means of active elements with more than two electrodes to which two signals are applied derived from the signal to be demodulated and having a phase difference related to the frequency deviation, e.g. phase detector

Modifications of demodulators to reject or remove amplitude variations by means of locked-in oscillator circuits

by means of sloping amplitude/frequency characteristic of tuned or reactive circuit (H 03 D 3/28 to H 03 D 3/32 take precedence)

Modifications of demodulators to reduce effect of temperature variations (automatic frequency control H 03 L)

by means of transit-time tubes

by deflecting an electron beam in a discharge tube (H 03 D 3/30 takes precedence)

by means of electromechanical devices (H 03 D 3/16 takes precedence) [3]

Circuits for demodulating amplitude-modulated or angle-modulated oscillations at will (H 03 D 9/00, H 03 D 11/00 take precedence)

Transference of modulation from one carrier to another, e.g. frequency-changing (H 03 D 9/00, H 03 D 11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as frequency-changers H 03 F)

by means of diodes (H 03 D 7/14 to H 03 D 7/22 take precedence)

having negative resistance characteristic, e.g. tunnel diode

by means of discharge tubes having more than two electrodes (H 03 D 7/14 to H 03 D 7/22 take precedence)

the signals to be mixed being applied between the same two electrodes

the signals to be mixed being applied between different pairs of electrodes

by means of semiconductor devices having more than two electrodes (H 03 D 7/14 to H 03 D 7/22 take precedence)

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 (H 03 D 7/20 takes precedence)

Demodulation or transference of modulation of modulated electromagnetic waves (devices or arrangements for demodulating light, transferring modulation in light waves G 02 F 2/00)

Demodulation using distributed inductance and capacitance, e.g. in feeder lines

for angle-modulated oscillations

Transference of modulation using distributed inductance and capacitance

11/

Super-regenerative demodulator circuits

11/

for amplitude-modulated oscillations

11/

by means of semiconductor devices having more than two electrodes

11/

for angle-modulated oscillations

11/

by means of semiconductor devices having more than two electrodes

13/

Circuits for comparing the phase or frequency of two mutually-independent oscillations