Digital circuit transmission device
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorYoshihisa Harada
Life of this patent
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Abstract
A digital line transmission unit can carry out switching between speech codecs during the same call to achieve balance between making effective use of a line and a high sound quality without bringing about a feeling of discomfort in a user by the switching. It includes in an encoder a first speech codec 7 with a high sound quality and a high bit rate, a second speech codec 8 with a reasonable sound quality but a low bit rate. It carries out switching between these speech codecs in response to the control information an operation monitoring controller 4 obtains by making a decision as to the traffic volume of the bearer line 111. The switching between the speech codecs is made during a speech pause a speech burst detector 31 in a signal detector 3 detects in an input speech signal.
Claims13
A digital line transmission unit for carrying out compression encoding, said digital line transmission unit comprising:
- an encoder/decoder including a first speech encoding unit for encoding and decoding a speech signal, a second speech encoding unit for encoding and decoding the speech signal, and a non-speech encoding unit for encoding and decoding a non-speech signal;
- signal discriminator including a speech burst detector for detecting as to whether an input signal to said encoder/decoder is a speech burst or speech pause, and a speech/non-speech signal discriminator for deciding as to whether the input signal is a speech signal or non-speech signal;
- a signal multiplexing/demultiplexing section for multiplexing outputs of said first speech encoding unit, said second speech encoding unit and said non-speech encoding unit;
- and
- a switching unit for supplying the input signal to one of said first speech encoding unit, said second speech encoding unit and said non-speech encoding unit, wherein
- when the input signal is the speech pause, switching between said first speech encoding unit and said second speech encoding unit is carried out to supply the input signal to one of them.
A digital line transmission unit comprising:
- a plurality of encoders that differ in an encoding scheme or in a bit rate of encoding;
- an interface for supplying outputs of said encoders to a line;
- a switching unit for selectively outputting a speech signal input to said switching unit to one of said plurality of encoders;
- and
- a controller for controlling a destination of the output of said switching unit in response to a traffic volume of the line, and for controlling switching timing of said switching unit in accordance with a speech level of the speech signal.
Dependencies are inferred from the claim text.