Systems employing more than two channels, e.g. quadraphonic (H04S5/00, H04S7/00 take precedence)

Introduced: January 1980

Title

Titles differ between systems:

IPC: Systems employing more than two channels, e.g. quadraphonic

CPC: Systems employing more than two channels, e.g. quadraphonic (H04S5/00, H04S7/00 take precedence)

Full titles differ between systems:

IPC:

Systems employing more than two channels, e.g. quadraphonic

CPC:

Systems employing more than two channels, e.g. quadraphonic (H04S5/00, H04S7/00 take precedence)

Pseudo-stereophonic systems Indicating arrangements of stereophonic systems; Control arrangements, e.g. balance control of stereophonic systems

CPC subdivides this area 4x more granularly than IPC with 3 additional codes.

3 codes are CPC-only extensions.

IPC defines codes here since 1980.

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H04S 3/002 +1 CPC CPC only CPC only
H04S 3/006 CPC only CPC only
H04S 3/008 CPC only CPC only
H04S 3/02 of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other since 1980 IPC+CPC Available in IPC and CPC

Class H04,2013–2023, worldwide · Source: EPO PATSTAT

Class H04,2013–2023, worldwide · Source: EPO PATSTAT