Method for non-linear signal processing in an echo canceller
AssigneeNokia Telecommunications Oy
InventorHeimo Lahdemaki
Life of this patent
Estimating the term…
Abstract
Non-linear signal processing is provided in an echo canceller, in which the level of the signals passing through the echo canceller from the near end to the far end is attenuated to a predetermined blocking level, when the level of the near end signals is lower than a given threshold level. The level of the signal passing through the echo canceller from the near end to the far end is raised in a ramp-like manner from the blocking level back to the normal level (T.sub.SUP), when the level (L.sub.Sin) of the near end signals again exceeds the given threshold level or in a double talk situation.
Claims14
A method for non-linear signal processing in an echo canceller, comprising:
- (a) measuring a level of a first end signal entering and passing through an echo canceller from a first end of a transmission connection on its way to a second end of the transmission connection;
- (b)(i) attenuating the level of said first end signal passing through said echo canceller to a predetermined blocking level when the level measured in step (a) is lower than a given threshold level, and
- (b)(ii) ramping-up the level of said first end signal passing through said echo canceller from said blocking level to a normal, unattenuated level, during a predetermined time interval, when the level measured in step (a) again exceeds said given threshold level, or a double talk situation is detected.
Dependencies are inferred from the claim text.