JPH04284743A - Communication equipment - Google Patents

Abstract

PURPOSE:To send a data at a high speed without losing the quality of a sent voice signal. CONSTITUTION:A band split filter 22 divides a voice signal into signals at high and low frequency bands. A low frequency coder 23 and a high frequency coder 24 code a high frequency voice signal and a low frequency voice signal. A multiplexer 25 does not multiplex the voice signal from the high frequency coder 24 when the data transmission quantity is much but decreases the voice signal from the low frequency coder 23 to increase the data transmission quantity, and the multiplexer 25 multiplexes each voice signal from the low frequency coder 23 and the high frequency coder 24 when the data transmission quantity is not much to reduce the data transmission quantity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device that multiplexes and transmits audio signals and data.

0002

2. Description of the Related Art Conventionally, as this type of communication device, for example, CCITT Recommendation G.1 shown in FIG. 721 ADP
CM (Adaptive Differential
There is a configuration using the Pulse Code Modulation (Pulse Code Modulation) method. ADPCM circuit 1 is 0~
A 3.4 KHz analog audio signal is encoded into a 32 Kbit/s audio signal using the ADPCM method. The multiplexer 2 receives the audio signal from the ADPCM circuit 1 and the audio signal from the ADPCM circuit 3.
2 Kbit/s data is input, and these audio signals and data are multiplexed. The multiplexed signal is 64Kb
It is sent out to the transmission line as a multiplexed signal at 1/s.

[0003] Furthermore, the G.I. 722 SBC
(Sub Band Coding) - There is also a communication device configured using the ADPCM method. An analog audio signal of 0 to 7 KHz is input to the band division filter 11,
The signal is divided into band signals of 0 to 4 KHz and 4 to 7 KHz. The ADPCM circuit 12 takes in low-frequency audio signal components of 0 to 4 kHz, and the ADPCM circuit 13 takes in high-frequency audio signal components of 4 to 7 kHz, encodes them, and outputs them. The multiplexer 14 receives the output signals and data from the circuits 12 and 13, multiplexes these signals, and sends the multiplexed signals to the transmission line. There are three types of this transmission mode. The first mode is to output a 64 Kbit/s audio signal without multiplexing data. Second, 56Kbit/s audio signal and 8Kbit/s data are multiplexed to 64Kbit/s.
This is a mode in which the signal is output as a bit/s multiplexed signal. Third, 48Kbit/s audio signal and 16K
bit/s data is multiplexed to 64Kbit/s
In this mode, the signal is output as a multiplexed signal.

0004

[Problems to be Solved by the Invention] However, in the conventional communication device shown in FIG. The quality of the audio was deteriorating. Therefore, there has been a demand for transmitting higher quality audio signals.

On the other hand, in order to meet this demand, the communication device shown in FIG.
Bandwidth is compressed to /s. Therefore, in this communication device, it is possible to transmit an audio signal with good sound quality. However, the data transmission amount decreases accordingly, and the data transmission rate increases from 32Kbit/s to 8Kbit/s.
s or 16 Kbit/s.

The present invention has been made to solve these problems, and an object of the present invention is to provide a communication device that can perform data transmission at high speed without impairing the quality of the transmitted voice.

[0007]

[Means for Solving the Problems] The present invention provides a band division filter that divides an audio signal into a high frequency band and a low frequency band, and a high frequency code that encodes the audio signal in the high frequency band. The multiplexing of the output signals and data of the encoder, the low frequency encoder that encodes the audio signal in the low frequency band, the high frequency encoder and the low frequency encoder, and the transmission amount of each of these signals is performed. It is configured to include a multiplexer that performs corresponding operations.

[0008] Furthermore, when the amount of data transmission is large, the multiplexer does not multiplex the audio signal from the high-band encoder, but reduces the audio signal from the low-band encoder to reduce the amount of data transmission. When the amount of data transmitted is small, the audio signals from the high-frequency encoder and the low-frequency encoder are multiplexed to reduce the amount of data transmitted.

[0009]

[Operation] When the amount of data transmission is large, the multiplexer reduces the amount of audio signal transmission and increases the amount of data transmission accordingly, and when the amount of data transmission is small, it increases the amount of audio signal transmission to compensate for that amount. Reduce data transmission amount.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the overall configuration of a communication device according to an embodiment of the present invention. The band division filter 22 that inputs the analog audio signal from the terminal 21 is, for example, a QMF (Quadrature Mirror Filter).
ter). This band division filter 2
2 frequency-divides an input audio signal of 0 to 7 kHz into a low frequency audio signal of 0 to 4 kHz and a high frequency audio signal of 4 to 7 kHz, and outputs the resultant signals. The audio signal having low frequency components is encoded in a low frequency encoder 23. Furthermore, the audio signal having high frequency components is encoded in the high frequency encoder 24. The encoding in each of these encoders 23 and 24 is, for example, ADPCM.
It is done by method. The multiplexer 25 receives the output signals of the encoders 23 and 24 and the data from the terminal 26. The multiplexer 25 appropriately multiplexes each signal as described later in accordance with the amount of data to be transmitted, and sends out the multiplexed signal to the transmission line 27. This transmission line 27 is, for example, an INS6
It is composed of 4th grade.

The separator 28 receives the multiplexed signal transmitted through the transmission line 27 and separates the audio signal and data from the multiplexed signal. The separated audio signal is sent to the low frequency decoder 2.
9 and the high band decoder 30, and the low band decoder 2
At 9, the audio signal having low frequency components is decoded. Furthermore, the high frequency decoder 30 decodes the audio signal having high frequency components. Furthermore, the output signals of each of these decoders 29 and 30 are given to a band synthesizer 31,
It is restored to an audio signal with the frequency band at the time of transmission. The restored audio signal is output to terminal 32. Furthermore, the data separated by the separator 28 is output to the terminal 33.

FIG. 2 is a circuit configuration diagram showing the internal configuration of the multiplexer 25. As shown in FIG. The multiplexer 25 has AND gates 41 to
43, an OR gate 44, and a control signal generation circuit 45. When the amount of data transmission input from the terminal 26 is small, the control signal generation circuit 45 operates as shown in FIG.
), (b), and (c) are generated. Furthermore, when the amount of data transmitted from the terminal 26 is large, control signals A, B, and C shown in FIGS. 5(a), (b), and (c) are generated. The AND gate 41 receives the low frequency code and control signal A output from the low frequency encoder 23.
is taken in, and the logical product is calculated and output. and·
The gate 42 takes in the high-frequency code and control signal B output from the high-frequency encoder 24, calculates the logical product thereof, and outputs the result. AND gate 43 receives input data and control signal C
is taken in, and the logical product is calculated and output. The OR gate 44 takes in the output signals of the AND gates 41 to 43, calculates their logical sum, and sends the result of the calculation to the transmission line 2.
Send to 7.

FIG. 3 is a circuit configuration diagram showing the internal configuration of the separator 28. The separator 28 includes AND gates 51 to 53
and a control signal generation circuit 54. The control signal generation circuit 54 generates control signals A and B similar to those generated by the control signal generation circuit 45 configured inside the multiplexer 25.
,C. AND gate 51 separates the low frequency code from the multiplexed signal and control signal A propagated through transmission line 27. AND gate 52 separates the high frequency code from the multiplexed signal and control signal B. AND gate 53 separates the data from the multiplexed signal and control signal C.

In such a configuration, when the data input to the terminal 26 is a small amount of data such as control information, the control signal generation circuit 45 operates as shown in FIGS. 4(a) to 4(c).
It generates control signals A to C shown in FIG. Therefore, from the AND gate 41 in the multiplexer 25, for example (d
) 40Kbit/s low-frequency audio signal a0 shown in
~a4 is output. Further, the AND gate 42 outputs, for example, 16 Kbit/s high frequency audio signals b0 and b1 shown in FIG. Further, from the AND gate 43, for example, the 8
Data c0 of Kbit/s is output. As a result, the signal output from the OR gate 44 becomes the multiplexed signal shown in FIG. 4(g). In other words, the low frequency audio signal a0
~a4, high frequency audio signals b0, b1, and data c0 are multiplexed into a 64 Kbit/s signal.

[0015] In this manner, the multiplexer 25 increases the amount of audio signal transmission when the amount of data transmission is small, and reduces the amount of data transmission accordingly. Therefore, when a small amount of data such as control information is transmitted, it is possible to transmit a high quality sound signal.

On the other hand, when the data input to the terminal 26 is a large amount of data such as image data, the control signal generating circuit 45 generates the control signals A to A shown in FIGS. Generate C. Therefore, from the AND gate 41 in the multiplexer 25, for example, 32 as shown in FIG.
Kbit/s low frequency audio signals a0 to a3 are output. Further, the AND gate 42 no longer outputs any high frequency audio signal as shown in FIG. 4(e). Furthermore, the AND gate 43 outputs, for example, 32 Kbit/s data c0 to c3 shown in FIG. As a result, the signal output from the OR gate 44 becomes the multiplexed signal shown in FIG. 4(g). That is, low frequency audio signals a0 to a3 and data c0 to c
3 becomes a multiplexed 64 Kbit/s signal.

In this manner, the multiplexer 25 stops multiplexing high-frequency audio signals when the amount of data transmission is large, and reduces multiplexing of low-frequency audio signals to reduce the amount of audio signal transmission. Then, the amount of data transmission is increased accordingly. For this reason,
It becomes possible to transmit large amounts of data such as image data at high speed. The reason for discontinuing the multiplexing of high-frequency audio signals is that the audio signals are mainly composed of low-frequency components, and the meaning of the audio can be fully understood even if some of the high-frequency audio signals are lost. This is because it is possible.

The multiplexed signal is passed through the separator 28 to
The control signals A to C in the multiplexer 25 are separated by the control signals A to C having the same timing, decoded, and output. Note that in this separation process, when the amount of data transmission is increased and the audio signal is decreased, an audio signal that is not multiplexed is generated. For this reason, the separation process corresponding to the audio signal that has not been multiplexed is performed with the audio signal set to zero.

[0019]

[Effects of the Invention] As explained above, according to the present invention, the multiplexer reduces the amount of audio signal transmission when the amount of data transmission is large and increases the amount of data transmission by that amount. If it is less, the amount of audio signal transmission is increased and the amount of data transmission is reduced accordingly.

[0020] Therefore, the amount of audio signal transmission increases or decreases in accordance with the amount of data transmission, so that appropriate amounts of data and audio signals are transmitted at the right time. As a result, a communication device that can transmit data at high speed without degrading the quality of the transmitted voice can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of a communication device according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram showing the internal configuration of a multiplexer in this embodiment.

FIG. 3 is a circuit configuration diagram showing the internal configuration of the separator in this embodiment.

FIG. 4 is a timing chart of each signal generated inside the multiplexer when the amount of data transmission is small.

FIG. 5 is a timing chart of each signal generated within the multiplexer when a large amount of data is transmitted.

FIG. 6 is a block diagram showing the configuration of a first conventional communication device.

FIG. 7 is a block diagram showing the configuration of a second conventional communication device.

[Explanation of symbols]

21...Audio signal input terminal 22...band division filter 23...Low band encoder 24...High frequency encoder 25...Multiplexer 26...Data input terminal 27...Transmission line 28...Separator 29...Low band decoder 30...High frequency decoder 31...Band synthesizer 32...Audio signal output terminal 33...Data output terminal

Claims (2)

[Claims] 1. A communication device that multiplexes and transmits an audio signal and data, comprising: a band division filter that divides the audio signal into a high frequency band and a low frequency band; a high-frequency encoder that encodes an audio signal, a low-frequency encoder that encodes the audio signal in the low frequency band, each output signal of the high-frequency encoder and the low-frequency encoder, and A communication device comprising: a multiplexer that multiplexes the data according to the amount of transmission of each of these signals. [Claim 2] When the amount of data transmission is large, the multiplexer does not multiplex the audio signal from the high-band encoder, reduces the audio signal from the low-band encoder, and reduces the amount of data transmission. and multiplexing each audio signal from the high-band encoder and the low-band encoder when the amount of data transmission is small;
The communication device according to claim 1, characterized in that the amount of data transmitted is reduced.