Details of transmission systems, not covered by a single one of groups; Details of transmission systems not characterised by the medium used for transmission

Introduced: September 1968

Last revised: January 2006

Classification Context

Section:: ELECTRICITY
Class:: ELECTRIC COMMUNICATION TECHNIQUE
Subclass:: TRANSMISSION

Additional Content

Glossary

Homodyne receiver A receiver which involves multiplying the modulated received signal by a local oscillator which has the same frequency as that associated with the received signal, so that the received signal will be directly converted into the baseband. Superheterodyne receiver superheterodyne receivers A receiver in which the frequency of the incoming signal is reduced in a mixer or frequency changer by heterodyning with another frequency at the local oscillator. (Heterodyning: combining two sinusoidal frequencies radio frequency waves in a non-linear device resulting in sum and difference frequencies). Synchrodyne receiver synchrodyne receivers A receiver in which a mixing carrier signal is inserted in exact synchronism with the original carrier at the transmitter. Used for the selective detection of signals coded in a certain way.

Limiting references

Demodulation or transference of modulation from one carrier to another

12 direct subcodes

Child Classifications

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H04B 1/02 Transmitters
H04B 1/06 Receivers
H04B 1/38 Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
H04B 1/59 Responders; Transponders
H04B 1/6 Supervising unattended repeaters
H04B 1/62 for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio
H04B 1/66 for reducing bandwidth of signals; for improving efficiency of transmission
H04B 1/68 for wholly or partially suppressing the carrier or one side band
H04B 1/69 Spread spectrum techniques
H04B 1/72 Circuits or components for simulating antennas, e.g. dummy antennas
H04B 1/74 for increasing reliability, e.g. using redundant or spare channels or apparatus
H04B 1/76 Pilot transmitters or receivers for control of transmission or for equalising

Top Applicants

Top 10 applicants by patent filingsfor class H04, 2013–2023, worldwide · Source: EPO PATSTAT

QUALCOMM US 97,396
HUAWEI TECHNOLOGIES COMPANY CN 96,502
SAMSUNG ELECTRONICS COMPANY KR 86,981
TELEFONAKTIEBOLAGET LM ERICSSON (PUBL) SE 55,869
HUAWEI TECHNOLOGIES COMPANY 55,349
LG ELECTRONICS KR 53,649
CANON 33,341
SONY CORPORATION JP 32,761
ZTE CORPORATION CN 32,274
GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORPORATION 28,327