Method and apparatus for echo suppression
AssigneeTelefonaktiebolaget LM Ericsson
InventorsJohan Gnosspelius, Patrik Sörqvist
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Abstract
The present invention relates to echo suppression in a telephony system wherein a communication link is established over an analogue network and a digital network. The disclosed echo suppression invention provides cost-effective ways of minimizing an echo arising in the public switched telephone network (PSTN) by calculating a first value for the energy level of the signal from the analogue to the digital network, and likewise calculating a second value for the energy level of the signal from the digital to the analogue network. The sound from the analogue network to digital network is transmitted in dependence of the results of a comparison between the first and second values.
Claims12
A method for suppressing echo in a telephone connection, a first part of said connection being connected through an analogue network and a second part of the connection being connected through a digital network, characterized by the steps of transmitting all sound from the digital network to the analogue network, determining a first value for the energy level of the signal from the analogue network to the digital network, determining a second value for the energy level of the signal from the digital to the analogue network;
- transmitting sound from the analogue network to the digital network in dependence of the result of a comparison between said first and second values.
An apparatus for suppressing echo in a telephone connection in which a first part of the connection is connected through an analogue network and a second part of the connection is connected through a digital network, characterized in that the apparatus comprises
- first detection means arranged to determine a first value of the energy level in the signal from the analogue network to the digital network;
- second detection means arranged to determine a second value of the energy level in the signal from the digital network to the analogue network;
- comparing means for comparing the first and the second value and transmit an output signal representing the result of the comparison;
- connection means arranged to always transmit the signal from the digital network to the analogue network, and to transmit or not transmit the signal from the analogue network to the digital network in dependence of the output signal from the comparing means.
Dependencies are inferred from the claim text.