Method and arrangement for changing source signal bandwidth in a telecommunication connection with multiple bandwidth capability

A digital radio telephone, comprising:

• a speech encoding arrangement,
• a speech signal input to the speech encoding arrangement,
• within the speech encoding arrangement a multiple mode speech encoder for encoding speech signals coupled to the speech signal input selectabily with a first encoding mode associated with a first bandwidth or a second encoding mode associated with a second bandwidth, and
• a soft bandwidth switching block with an input coupled to the speech signal input and an output coupled to the multiple mode speech encoder, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal coupled to the multiple mode speech encoder as a response to an instruction for changing speech signal bandwidth.

A transcoder and rate adaptor unit of a cellular radio system, comprising:

• a speech encoding arrangement,
• a speech signal input to the speech encoding arrangement,
• within the speech encoding arrangement a multiple mode speech encoder for encoding speech signals coupled to the speech signal input selectabily with a first encoding mode associated with a first bandwidth or a second encoding mode associated with a second bandwidth, and
• a soft bandwidth switching block with an input coupled to the speech signal input and an output coupled to the multiple mode speech encoder, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal coupled to the multiple mode speech encoder as a response to an instruction for changing speech signal bandwidth.

A digital radio telephone, comprising:

• a speech decoding arrangement,
• a speech signal input to the speech decoding arrangement,
• within the speech decoding arrangement a multiple mode speech decoder for decoding speech signals coupled to the speech signal input selectabily with a first decoding rate associated with a first bandwidth or a second decoding rate associated with a second bandwidth, and
• a soft bandwidth switching block with an input coupled to the multiple mode speech decoder and an output, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal received from the multiple mode speech decoder as a response to an instruction for changing speech signal bandwidth.

A transcoder and rate adaptor unit of a cellular radio system, comprising:

• a speech decoding arrangement,
• a speech signal input to the speech decoding arrangement,
• within the speech decoding arrangement a multiple mode speech decoder for decoding speech signals coupled to the speech signal input selectabily with a first decoding rate associated with a first bandwidth or a second decoding rate associated with a second bandwidth, and
• a soft bandwidth switching block with an input coupled to the multiple mode speech decoder and an output, said soft bandwidth switching block being arranged to gradually change the bandwidth of a speech signal received from the multiple mode speech decoder as a response to an instruction for changing speech signal bandwidth.