A method and a device for speech encoding

Claim 2

A speech encoding method according to claim 1, characterized in that said first analysis (10, 32, 33) is a short-term LPC-analysis (10, 32, 33) and said second analysis (11, 31, 34, 35) is a long-term LTP-analysis (11, 31, 34, 35).

Claim 3

A speech encoding method according to claim 1 or 2, characterized in that the second prediction parameters (321, 322, 341) modelling the examined speech frame comprise an excitation vector (61-61"'), said first product and second product (321, 322, 341, 342, 351) comprise LPC-parameters (321) modelling the speech frame examined in the first time slot, and an LTP-analysis residual signal (351) modelling the examined speech frame in the second time slot, and that the number of bits used for presenting said excitation vector (61-61"') used for modelling the examined speech frame is determined based upon said LPC-parameters (321) and LTP-analysis residual signal (351).

Claim 4

A speech encoding method according to claim 1 or 2, characterized in that said second prediction parameters (331, 341, 342) comprise an LTP-pitch lag term, an analysis/synthesis filter (10, 12, 32, 39) is used in the LPC-analysis, an open loop with a gain factor (341) is used in the LTP-analysis, the performance (m) of the analysis/synthesis filter (10, 12, 32, 39) used in the LPC-analysis (32) is determined prior to determining the number of bits used for presenting the first and the second prediction parameters (321, 322, 331, 341, 342, 351), the open loop gain factor (341) is determined in the LTP-analysis (31,34) prior to determining the number of bits used for presenting the first and second prediction parameters (321, 322, 331, 341, 342, 351), and the accuracy used for calculating said LPC-pitch lag term used in modelling the examined speech frame is determined based upon said model order (m) and open loop gain factor (341).

Claim 5

A speech encoding method according to claim 4, characterized in that when determining said second prediction parameters (331, 341, 342) , closed loop LTP-analysis (31, 35, 391) is used in order to determine the LTP-pitch lag term with a higher accuracy.

Claim 6

A telecommunication system (110) comprising communication means (111, 111', 112, 113, 114, 115, 116, 117, 118, 119) such as mobile stations (111, 111'), base stations (112), base station controllers (113), mobile communication switching centres (114), telecommunication networks (115, 116) and terminal devices (117, 118, 119) for establishing a telecommunication connection and transferring information between said communication means (111, 111', 112, 113, 114, 115, 116, 117, 118, 119), said communication means (111, 111', 112, 113, 114, 115, 116, 117, 118, 119) comprise a speech encoder (103), which said speech encoder (103) further comprises means for dividing a speech signal (301) into speech frames for encoding by frames, means for performing a first analysis (10, 32, 33) to the examined speech frame in order to form a first product (321, 322), which first product comprises prediction parameters (321, 322) modelling the examined speech frame in a first time slot, means for performing a second analysis (11, 31, 34, 35) to the examined speech frame in order to form a second product (341, 342, 351), which second product comprises prediction parameters (341, 342, 351) modelling the examined speech frame in a second time slot, and means for presenting the first and the second prediction parameters (321, 322, 341, 342, 351) in a digital form, characterized in, that it further comprises means (38, 39, 41, 42, 43, 44, 45, 46, 48, 71, 73) for analyzing the performance of the first analysis (10, 32, 33) and the second analysis (11, 31, 34, 35), based upon the first product (321, 322) and the second product (341, 342, 351), and that said performance analyzing means (38, 39, 41, 42, 43, 44, 45, 46, 48, 71, 73) have been arranged to determine the number of bits used for presenting one of the following parameters: the first prediction parameters (321, 322, 331), the second prediction parameters (341, 342, 351), and a combination of them.

Claim 7

A communication device comprising means (103, 104, 105, DPLX, ANT, 106 107) for transferring speech and a speech encoder (103) for speech encoding, which speech encoder (103) comprises means for dividing a speech signal (301) into speech frames for speech encoding by frames, means for performing a first analysis (10, 32, 33) to the examined speech frame in order to form a first product (321, 322), which first product comprises first prediction parameters (321, 322) modelling the examined speech frame in a first time slot, means for performing a second analysis (11, 31, 34, 35) to the examined speech frame in order to form a second product (341, 342, 351), which second product comprises second prediction parameters (341, 342, 351) modelling the examined speech frame in a second time slot, and means for presenting the first and the second prediction parameters (321, 322, 341, 342, 351) in a digital form, characterized in, that it further comprises means (38, 39, 41, 42, 43, 44, 45, 46, 48, 71, 73) for analyzing the performance of the first analysis (10, 32, 33) and the second analysis (11, 31, 34, 35) of the speech encoder (103) based upon the first product (321, 322) and the second product (341, 342, 351), and that said performance analyzing means (38, 39, 41, 42, 43, 44, 45, 46, 48, 71, 73) have been arranged to determine the number of bits used for presenting one of the following parameters: the first prediction parameters (321, 322, 331), the second prediction parameters (341, 342, 351) and a combination of them.

Claim 8

A speech encoder (103), which comprises means for dividing a speech signal (301) into speech frames for speech encoding by frames, means for performing a first analysis (10, 32, 33) to the examined speech frame in order to form a first product (321, 322), which first product comprises first prediction parameters (321, 322) modelling the examined speech frame in a first time slot, means for performing a second analysis (11, 31, 34, 35) to the examined speech frame in order to form a second product (341, 342, 351), which second product comprises second prediction parameters (341, 342, 351) modelling the examined speech frame in a second time slot, and means for presenting the first and the second prediction parameters (321, 322, 341, 342, 351) in a digital form, characterized in, that it further comprises means (38, 39, 41, 42, 43, 44, 45, 46, 48, 71, 73) for analyzing the performance of the first analysis (10, 32, 33) and the second analysis (11, 31, 34, 35) of the speech encoder (103) based upon the first product (321, 322) and the second product (341, 342, 351), and that said performance analyzing means (38, 39, 41, 42, 43, 44, 45, 46, 48, 71, 73) have been arranged to determine the number of bits used for presenting one of the following parameters: the first prediction parameters (321, 322, 331), the second prediction parameters (341, 342, 351) and a combination of them.

Claim 9

A speech encoder comprising means for receiving speech from a telecommunication connection in form of speech parameters (392, 382, 383), which speech parameters (392, 382, 383) comprise first prediction parameters (321, 322, 331) for modelling speech in a first time slot and second prediction parameters (341,392) for modelling speech in a second time slot, generating means (20, 21, 22, 24, 90, 91, 93-93"', 94, 95) for generating a synthesized speech signal (ss(n)) modelling the original speech signal (s(n)) based upon said speech parameters (392, 382, 383), characterized in, that said generating means (20, 21, 22, 24, 90, 91, 93-93"', 94, 95) comprise a mode selector (91), said speech parameters (392, 382, 383) comprise information parameters (382, 383), said mode selector (91) has been arranged to select a correct speech decoding mode for the first prediction parameters (321, 392) and the second prediction parameters (34, 392) based upon said information parameters (382, 383).