DIFF Subgroup
H04L 25/49 using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels
Introduced: July 1974
Full Title
Baseband systems > Synchronous or start-stop systems, e.g. for Baudot code > Transmitting circuits; Receiving circuits > using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels
CPC subdivides this area 3x more granularly than IPC with 4 additional codes.
4 codes are CPC-only extensions.
IPC defines codes here since 1980.
Child Classifications
Navigate with arrow keys, Enter to open
- H04L 25/493 by transition coding, i.e. the time-position or direction of a transition being encoded before transmission since 1980 IPC+CPC Available in IPC and CPC
- H04L 25/497 by correlative coding, e.g. partial response coding or echo modulation coding since 1980 +1 CPC IPC+CPC Available in IPC and CPC
Top Applicants
Top Applicants (IPC)
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
Top Applicants (CPC)
Class H04,2013–2023, worldwide · Source: EPO PATSTAT
- HUAWEI TECHNOLOGIES COMPANY CN 101,476
- QUALCOMM US 101,139
- SAMSUNG ELECTRONICS COMPANY KR 96,655
- TELEFONAKTIEBOLAGET LM ERICSSON (PUBL) SE 57,744
- LG ELECTRONICS KR 55,253
- HUAWEI TECHNOLOGIES COMPANY 54,181
- SONY CORPORATION JP 35,309
- ZTE CORPORATION CN 32,950
- INTEL CORPORATION US 27,533
- GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORPORATION CN 27,498