Data processing: speech signal processing – linguistics – language – Speech signal processing – For storage or transmission
Reexamination Certificate
2000-08-03
2004-06-15
Dorvil, Richemond (Department: 2654)
Data processing: speech signal processing, linguistics, language
Speech signal processing
For storage or transmission
C704S229000, C704S230000, C714S794000
Reexamination Certificate
active
06751586
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a audio decoding device which is employed in a radio communication system such as a digital audio communication, a audio packet transmission, etc.
Then, a radio communication system to which the audio decoding device in the prior art is applied and which is employed in a normal digital audio communication, etc. will be explained hereunder.
FIG. 10
is a block diagram showing a schematic configuration of a normal radio communication system.
As shown in
FIG. 10
, a radio communication system
1
A comprises a plurality of mobile radio stations
2
A and base radio stations
3
A which relay and connect mutually these mobile radio stations
2
A. A audio coding device which codes the input audio and then outputs a transmission signal and a audio decoding device which decodes an incoming received signal and then outputs the audio are built in each of these mobile radio stations
2
A and base radio stations
3
A.
FIG. 11
is a block diagram showing a schematic configuration of an interior of the audio coding device which corresponds to the audio decoding device in the prior art.
The audio coding device
8
shown in
FIG. 11
comprises a audio input processing means
81
for digitally converting the input audio and then outputting the digital signal as audio data; a audio code processing means
82
for coding the audio data which are output from the audio input processing means
81
and then outputting the audio code; a transmission line code processing means
83
for calculating coded data to which redundancy is added to enable the conversion to the audio code once again even if an error is added to the audio code on the transmission line to some extent; a modulation processing means
84
for applying a modulation process to the coded data to output the transmission signal; and a transmission processing means
85
for transmitting the transmission signal which is modulated by the modulation processing means
84
onto the transmission line.
Then, the audio decoding device which has a function for receiving the transmission signal from the transmission processing means
85
in the audio coding device
8
via the transmission line and then decoding the received signal to output the audio will be explained hereunder.
In the prior art, as such audio decoding device, for example, a device set forth in Patent Application Publication (KOKAI) Hei 4-100422 has been known.
FIG. 12
is a block diagram showing a schematic configuration of an interior of the audio decoding device in the prior art.
The audio decoding device
100
shown in
FIG. 12
comprises a demodulation processing means
101
for receiving the signal, to which the error may be added over the transmission line, as the received signal and then demodulating the received signal into the coded data; an error correction processing means
102
for deciding whether or not the error is added to the coded data, then deciding whether or not the error is correctable if the error is added, then applying an error correction process to the coded data if the error is not added or if the added error is correctable, and then decoding the audio code to generate audio data; a audio decoding means
103
for decoding the audio code to generate the audio data; and a audio output processing means
104
for outputting the audio data which are output from the audio decoding means
103
.
The error correction processing means
102
decodes the coded data to generate the audio code if the error is not added to the coded data, then applies the error correction process to the coded data if the error is not added to the coded data and the error is correctable, then decodes the coded data to generate the audio code, and then transmits the generated audio code to the audio decoding means
103
via a switch
105
and stores/holds the generated audio code and the coded data in a buffer
106
frame by frame.
Also, the error correction processing means
102
generates interpolation process information based on the coded data if the error is added to the coded data and the error is uncorrectable, then reads the audio code, which corresponds to the coded data being equivalent to the preceding frame of the coded data, from the buffer
106
without decoding the coded data, and then transmits the read audio code to the audio decoding means
103
via the switch
105
based on the interpolation process information.
In this manner, according to the audio decoding device in the prior art, even in the case that the uncorrectable error is added to the coded data, the interpolation process of the coded data containing the uncorrectable error can be achieved by reading the audio code, which is concerned with the coded data being equivalent to the preceding frame of the coded data containing the uncorrectable error, from the buffer
106
and then transmitting the audio code to the audio decoding means
103
.
However, according to the above audio-decoding device in the prior art, in the case that the audio data is generated by decoding the audio code, which is concerned with the coded data containing the uncorrectable error caused due to, for example, aggravating circumstances of the transmission line, as shown in
FIG. 13
, the audio code which associates with the preceding frame is read from the buffer
106
in unit of frame based on the interpolation process information, in place of decoding of the audio data containing the uncorrectable error (step S
101
), then the audio code is transmitted to the audio decoding means
103
(step S
102
), then the interpolation process is executed in unit of frame (step S
103
), and then the audio code is decoded to generate the audio data (step S
104
). Therefore, there is a problem that distortion or disconnection of the output audio is generated by carrying out the interpolation process in unit of frame.
SUMMARY OF THE INVENTION
The present invention has been made in light of the above problems, and it is an object of the present invention to provide a audio decoding device which is capable of suppressing generation of the distortion and the disconnection of the output audio to the minimum even when the signal which contains the uncorrectable error caused due to the aggravating circumstances of the transmission line is received.
In order to achieve the above object, a audio decoding device of the present invention comprises a reception processing means for receiving a signal from a transmission line as a received signal; a demodulation processing means for demodulating the received signal which is received by the reception processing means into coded data; a soft decision information generating means for generating a soft decision information indicating a current situation of the transmission line, based on coded data which are demodulated by the demodulation processing means; an error correction processing means for decoding the coded data to output a audio code and also outputting interpolation process information based on the coded data if it is decided that an uncorrectable error is added to the coded data which are demodulated by the demodulation processing means; a audio decoding processing means for reading interpolation information in a preceding frame based on interpolation process information concerning to the audio code, then applying an interpolation process to the audio code in unit of bit based on interpolation information and soft decision information, and then generating audio data by decoding the audio code which is subjected to the interpolation process if the audio code associated with the coded data, to which the uncorrectable error is added, is received from the error correction processing means; and a audio output processing means for outputting the audio data generated by the audio decoding processing means.
Therefore, according to the audio decoding device of the present invention, if the uncorrectable error is caused due to the aggravating circumstances of the transmission line, the interpolation process can be applied to the audio code in unit of bit b
Dorvil Richemond
Matsushita Electric - Industrial Co., Ltd.
Pearne & Gordon LLP
Storm Donald L.
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