H - Electricity – 04 – B
Patent
H - Electricity
04
B
H04B 1/16 (2006.01) G10L 19/00 (2006.01) H04L 1/00 (2006.01) G10L 11/02 (2006.01)
Patent
CA 2140364
CLAIMS 1. A method in a frame based radio communication system, for concealing rejected frames in a speech decoder of a receiver, which speech decoder is of the source-filter type and is controlled by received parameters representing audio signals transmitted over a communication channel on a frame by frame basis, said method being characterized by: (a) accepting or rejecting received frames depending on whether the parameters contained therein are considered to represent proper audio signals; (b) detecting whether accepted frames represent primarily speech or background sounds; (c) concealing rejected frames by updating the parameters contained therein in accordance with a first concealing algorithm if the last accepted frame primarily repre- sented speech and in accordance-with a second concealing algorithm if the last accepted frame contained primarily background sounds. 2. The method of claim 1, characterized in that said second concealing algorithm comprises locking filter and gain parameters to their values in the last accepted frame. 3. The method of claim 2, characterized by said second concealing algorithm decreasing the output level of the audio signal from said speech decoder when a first predetermined number of consecutive frames have been rejected. 4. The method of claim 3, characterized by said second concealing algorithm repeatedly decreasing the output level of the audio signal from said speech decoder each time said first predeter- mined number of further consecutive frames have been rejected. 21 5. The method of any of the preceding claims, characterized by said first concealing algorithm interpolating predetermined received parameters from the first rejected frame with corre- sponding parameters from the last accepted frame. 6. The method of claim 5, characterized by said first concealing algorithm interpolating predetermined received parameters from the current rejected frame with corresponding parameters from the previous rejected frame and decreasing the output level of the audio signal from said speech decoder if at least two consecutive frames have been rejected. 7. The method of claim 6, characterized by said first concealing algorithm muting the output signal from said speech decoder if a second predetermined number of further consecutive frames have been rejected. 8. The method of any of the preceeding claims, characterized in that transmitted parameters are encoded in accordance with a first encoding algorithm if they represent speech and in accordance with a second encoding algorithm if they represent background sounds. 9. The method of any of the preceeding claims, characterized in that received parameters are decoded in accordance with a first decoding algorithm if they represent speech and in accordance with a second decoding algorithm if they represent background sounds. 10. An apparatus in a frame based radio communication system, for concealing rejected frames in a speech decoder of a receiver, which speech decoder is of the source-filter type and is controlled by received parameters representing audio signals transmitted over a communication channel on a frame by frame basis, said apparatus being characterized by: (a) means (20, 28) for accepting or rejecting received 22 frames depending on whether the parameters contained therein are considered to represent proper audio sig- nals; (b) means (34) for detecting whether accepted frames repre- sent primarily speech or background sounds; (c) means (32) for concealing rejected frames by updating the parameters contained therein in accordance with a first concealing algorithm (LOOP S) if the last accepted frame primarily represented speech and in accordance with a second concealing algorithm (LOOP B) if the last accepted frame contained primarily background sounds. 11. The apparatus of claim 10, characterized by means (32) for performing said second concealing algorithm by locking filter and gain parameters to their values in the last accepted frame. 12. The apparatus of claim 11, characterized by said means for performing said second concealing algorithm decreasing the output level of the audio signal from said speech decoder (40) when a first predetermined number of consecutive frames have been rejected. 13. The apparatus of claim 12, characterized by said means for performing said second concealing algorithm repeatedly decreasing the output level of the audio signal from said speech decoder each time said first predetermined number of further consecutive frames have been rejected. 14. The apparatus of any of the preceding claims 10-13, charac- terized by means (32) for performing said first concealing algorithm by interpolating predetermined received parameters in the first rejected frame with corresponding parameters from the last accepted frame. 15. The apparatus of claim 14, characterized by said means for 23 performing said first concealing algorithm interpolating predetermined received parameters in the current rejected frame with corresponding parameters from the previous rejected frame and decreasing the output level of the audio signal from said speech decoder if at least two consecutive frames have been rejected. 16. The apparatus of claim 15, characterized by said means for performing said first concealing algorithm muting the output signal from said speech decoder if a second predetermined number of further consecutive frames have been rejected. 17. The apparatus of any of the preceeding claims, characterized by means for encoding transmitted parameters in accordance with a first encoding algorithm if they represent speech and in accordance with a second encoding algorithm if they represent backgropund sounds. 18. The apparatus of any of the preceeding claims, characterized by means (38, 40) for decoding received parameters in accordance with a first decoding algorithm if they represent speech and in accordance with a second decoding algorithm if they represent bachground sounds.
Dans un récepteur d'un système de radiocommunications géré par trames, des trames rejetées sont dissimulées en fonction d'un premier algorithme (BOUCLE S) si la dernière trame acceptée est une trame vocale, et en fonction d'un second algorithme (BOUCLE B) si la dernière trame acceptée est une trame contenant des bruits de fond.
Bergstrom Rolf Anders
Jansson Fredrik Klas Janis
Wigren Karl Torbjorn
Marks & Clerk
Telefonaktiebolaget Lm Ericsson
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