JPH05114888A - Variable bit-type adpcm transcoder - Google Patents

Abstract

PURPOSE:To improve the transfer characteristic and opposite station by allocating in 3-bit encoding to a voice signal and 5-bit encoding to a modem signal and transferring a discriminating signal to the opposite station. CONSTITUTION:The encoding bit number of information of each channel, that is, the information showing whether or not the signal is a voice signal or a modem signal in a voice band is sent to the opposite station. A discrimination circuit 36 discriminates the presence or absence of a data signal by comparing the data optimum scale factor to be outputted from a scale factor calculation circuit 35 with the set threshold value to be outputted to a bit number decision circuit 37. Further, the bit number decision circuit 37 outputs a signal requiring the data optimum encoding bit number (5 bit) when the data signal presence discrimination result outputted from the discrimination circuit 36 shows the presence of data and a signal requiring the voice encoding bit number (3 bit) in other time to an ADPCM encoding circuit 32 using an encoding bit number control signal line 38.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to two 2M-system PCM primary group signals (hereinafter referred to as 2M PCM signals) and ADPCM.
Primary group signal (hereinafter referred to as 2M ADPCM signal) 1
The present invention relates to an ADPCM transcoder that performs mutual code conversion with a book.

[0002]

2. Description of the Related Art Conventionally, in this type of ADPCM transcoder, the number of encoded bits has been fixed at 4 bits.

[0003]

In the conventional ADPCM transcoder, the International Telegraph and Telephone Consultative Committee (CCITT: Intern) is used as an ADPCM coding algorithm.
national Telegram and Tele
phone Consistent Committee
ee) Recommendation G. 721, or A unique to each company
It used the DPCM encoding algorithm. Therefore, Recommendation G. If the 721 is used, there is a problem that a modem signal in a voice band of 9600 b / s or more cannot be transmitted.
Further, there is a problem in that it is not possible to face ADPCM transcoders of other companies by using ADPCM encoding algorithms unique to each company. One of the causes is that the number of encoded bits is fixed.

The present invention aims to solve the above problems of the conventional transcoder and to provide a variable bit type ADPCM transcoder which is excellent in both transmission characteristics and playability.

[0005]

An ADPCM transcoder for performing mutual code conversion between two 2M system PCM primary group signals and one ADPCM primary group signal, in which a PCM signal is input and the number of encoded bits is controlled. AD controlled by signal
An ADPCM encoding circuit that outputs a PCM signal and this A
A speed control calculation circuit for inputting a DPCM signal, controlling a scale factor, and calculating and outputting a first-order linear combination coefficient of the scale factor;
The M signal is input, the scale factor for speech optimization, the scale factor for data optimization, and the scale factor calculated by the first-order linear combination of these are calculated and calculated, controlled by the first-order linear combination coefficient, A scale factor calculation circuit that outputs the data optimum scale factor to the next stage and sends the calculated scale factor to the speed control calculation circuit as the scale factor, and the output data optimum scale factor is predetermined. A determination circuit for determining the presence or absence of data by comparing the threshold value with a threshold value, and a bit for issuing a coded bit number control signal determined according to whether the determination result of the determination circuit is data or no data A number determining circuit and the A
A transmitter having a format conversion circuit that rearranges the DPCM signal into a predetermined frame configuration based on the bit number control signal, and a bit number control signal that determines the bit number from the received signal is extracted and predetermined. A format conversion circuit for returning to the signal format, a bit number determination circuit for extracting the number of bits returned to the predetermined signal format by the format conversion circuit and outputting a bit number control signal, A variable bit type ADPCM transcoder comprising: a receiving unit having an ADPCM decoding circuit for varying the decoding bit number based on the output bit number control signal. Further, according to the present invention, as an ADPCM encoding algorithm, a proposal G.G. from the International Telegraph and Telephone Consultative Committee (hereinafter abbreviated as CCITT). 723 is selected, and it is determined whether the input signal is a voice signal or a voice band modem signal according to the size of the scale factor in the ADPCM coding algorithm. Variable bit type ADP of the preceding paragraph characterized by assigning 5-bit encoding to each band modem signal
A CM transcoder is obtained. Further, according to the present invention, CCITT Recommendation G.264 is used as a time slot of a multiplexing frame of an ADPCM signal. 761 timeslot 0
The variable bit ADPCM transcoder of the preceding paragraph is obtained, which is characterized in that the information of the number of coded bits of each channel using, that is, whether it is a voice signal or a modem signal is transmitted to the game.

[0006]

The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of a basic configuration of a variable bit type ADPCM transcoder of the present invention, and 11 and 12 are 2M PCM.
Signal input terminals, 13 and 14 are 2M PCM signal output terminals, 15 and 16 are PCM line interface circuits, 1
7 is a format conversion circuit, 18 and 19 are PCM / AD
PCM encoding / decoding circuit, 20 is an ADPCM line interface circuit, and 21 and 22 are 2M ADPCM signal output terminals.

The PCM signal input from the PCM signal input terminals 11 and 12 is a PCM line interface circuit 1.
The transmission line code is code-converted by 5 and 16 into an internal processing code, and alarm detection and synchronization processing are performed and input to the format conversion circuit 17.

In the format conversion circuit 17, the input PCM
Signaling information of the signal is extracted and PCM / AD of the next stage is extracted.
The timing is adjusted and output for the processing in the PCM encoding / decoding circuits 18 and 19.

PCM / ADPCM encoding / decoding circuit 1
In 8 and 19, the 8-bit PCM signal of each channel is
The DPCM signal is code-converted and output to the format conversion circuit 17. In addition, in the conventional ADPCM transcoder,
The coded bits at this time are 4 bits. Therefore, there was a choice between sacrificing modem transmission characteristics or facing.

Therefore, in the present embodiment, CCITT Rec. G. 723 is selected, and it is determined whether the input signal is a voice signal or a voice band modem signal according to the size of the scale factor in the ADPCM coding algorithm. Five-bit coding is assigned to each band modem signal.

In the format conversion circuit 17, the PCM /
ADPCM signal output from ADPCM encoding / decoding circuits 18 and 19, encoded bit control signal, and input PC
From the signaling information, alarm information, etc. extracted from the M signal, the recommendation proposal G.M. The ADPCM signal format described in reference numeral 761 is formed and output to the ADPCM line interface circuit 20.

At this time, regarding the signaling information, the G.
It is multiplexed in the time slot 16 of the 2M multiplexed frame as defined by H.761. Although the multiplexing of the ADPCM signal is specified as shown in FIG. 3, the multiplexing frame is changed as shown in FIG. 4 in order to allocate 5-bit coding to the modem signal in the voice band. That is, since the voice signal is encoded into 3 bits, it is inserted into the upper 3 bits as shown by the time slot 3 in FIG.
Since a voice band modem signal is encoded into 5 bits, for example, when channel 1A is a voice band modem signal and channel 2A is a voice signal, the least significant bit is as shown in time slot 1. At the position (bit 8), the least significant bit of channel 1A (bit 1 of the 5th bit)
A ₅ ) is inserted. When channel 5A is a voice signal and channel 6A is a voice signal of a modem signal in the voice band, the position of the least significant bit (bit 4) of the bits assigned to channel 5A as shown in time slot 5. The least significant bit of the channel 6A (the fifth bit, bit 6A ₅ ) is inserted into the channel.

By the way, the time slot 0 of the multiplexed frame of the 2M ADPCM signal is CCIT as shown in FIG.
Recommendation from G.T. 761 and is roughly classified into a case where frame alignment is included (upper part of FIG. 5) and a case where frame alignment is not included (lower part of FIG. 5). In FIG. 5, bit 1 (S1) is a preparation bit for international communication and is normally fixed to 1. Bit 3 (RMTA) and bit 4 (RMTB) are bits for transmitting a game alarm (remote alarm) of two 2M PCM signals,
Bit 5 (TRS A) and bit 6 (TRS B) are transparent transmission bits of two 2M PCM signals, and bit 7 (AIS
A) and bit 8 (AIS B) are two 2M PCM
It is the AIS signal transmission bit of the signal.

In this embodiment, as shown in FIG. 6, these bits of time slot 0 are effectively used, and the information of the number of coded bits of each channel, that is, whether it is a voice signal or a voice band modem signal is used. Information on whether or not there is is transmitted to the opposite station, and the number of encoded bits is matched. In FIG. 6, A1 to A16 are bits for transmitting information of channels 1A to 16A, and B1 to B16 are channels 1
It is a bit for transmitting information of B to 16B. Information from channels 17A to 31A is transmitted by bits A1 to A15 of the next multiframe. Further, the information of channels 17B to 31B is similarly transmitted by the bits of B1 to B15 of the next multiframe.

ADPCM line interface circuit 20
Then, the transmission 2M ADPCM signal is code-converted into a transmission path code and output from the 2M ADPCM signal output terminal 21 to the outside.

The 2M ADPCM signal input terminal 22
The received ADPCM signal input by the above is code-converted from the transmission path code to the internal processing code by the ADPCM line interface circuit 20, and is subjected to alarm detection and synchronization processing and is input to the format conversion circuit 17.

In the format conversion circuit 17, the input ADP
The signaling information of the CM signal is extracted, and the PCM /
The timing is adjusted and output for the v-th processing in the ADPCM encoding / decoding circuits 18 and 19. Along with this, information on the number of coded bits of each channel inserted in the time slot 0, that is, information on whether it is a voice signal or a voice band modem signal is extracted to extract the PCM / ADPCM code. Decoding / decoding circuit 18
And 19 are output.

PCM / ADPCM encoding / decoding circuit 1
In 8 and 19, the received ADPCM signal of each channel is code-converted into a PCM signal on the basis of the information on the number of coded bits and output to the format conversion circuit 17.

In the format conversion circuit 17, PCM /
The PCM signal output from the ADPCM encoding / decoding circuits 18 and 19 and the alarm information and signaling information extracted and processed from the input ADPCM signal are stored in a predetermined frame format, for example, CCITT Recommendation Proposed G.
PCM line interface circuit 1 reassembled into 704
Output to 5 and 16.

In the PCM line interface circuits 15 and 16, the transmission 2M PCM signal is code-converted into a transmission path code and output from the 2M PCM signal output terminals 13 and 14 to the outside.

By the way, the circuit of FIG. 2 can be applied as the encoding circuit of the PCM / ADPCM encoding / decoding circuits 18 and 19 of the present invention. In FIG. 2, 31 is a PCM signal input terminal, 32 is an ADPCM encoding circuit, and 33 is ADP.
A CM signal output terminal, 34 is a speed control calculation circuit, 35 is a scale factor calculation circuit, 36 is a determination circuit, 37 is a bit number determination circuit, and 38 is a coded bit number control signal line.

Next, this circuit will be described with reference to the drawings. AD
In the PCM encoding circuit 32, the format conversion circuit 17
The PCM signal input from AD is used as the number of encoded bits of the ADPCM encoding algorithm according to the signal of the encoded bit number control signal line 38 output from the bit number determination circuit 37.
The code is converted into a PCM signal and sent to the speed control calculation circuit 4 and the scale factor calculation circuit 5. At the same time, it outputs the format conversion circuit 17.

In the speed control calculation circuit 34, the ADP output from the ADPCM encoding circuit 32 is output.
From the CM signal and the scale factor output from the scale factor calculation circuit 35, a first-order linear combination coefficient (hereinafter referred to as A1) required when obtaining the scale factor is calculated and output to the scale factor calculation circuit 35. ..

In the scale factor calculation circuit 35, the ADPCM output from the ADPCM encoding circuit 32 described above is output.
The voice optimum scale factor and the data (voice band modem signal) optimum scale factor are calculated from the signal and the output A1 of the speed control calculation circuit 34, and the scale factor is calculated from the linear combination of both.

The scale factor referred to here is AD
It is a coefficient that determines the quantization step size used when encoding (decoding) a PCM signal, and varies in proportion to the variance of the input signal. Therefore, the quantization step size will also vary according to the variance of the input signal, but this is not enough, and when a voice signal with a large variance is input, the quantization step size suitable for the voice signal can be determined, Further, when a data signal with a small variance is input, it is desirable to be able to determine the quantization step size suitable for the data signal.

Therefore, the scale factor is represented by a linear linear combination of the voice optimum scale factor and the data optimum scale factor. When the voice signal is input, the weighting of the voice optimum scale factor becomes large, and the data signal is input. Then, the weighting of the scale factor for data optimization becomes large.

By the way, since the voice optimum scale factor is calculated by a linear linear combination of the input ADPCM signal and the scale factor, the voice optimally scales sensitively to the dispersion variation of the input signal. The data optimization scale factor is obtained by passing the voice optimization scale factor through a low pass filter.

The decision circuit 36 decides the presence or absence of a data signal by comparing the data optimum scale factor output from the scale factor calculation circuit 35 with a predetermined threshold value and outputs it to the bit number decision circuit 37. There is. In the bit number determination circuit 37, when the data signal presence / absence determination result output from the determination circuit 36 indicates that there is data, a signal requesting the data optimal encoding bit number (5 bits) is output, and in other cases, the voice code is output. A signal requesting the number of encoded bits (3 bits) is output to the ADPCM encoding circuit 32 using the encoding bit number control signal line 38.

By the way, as the ADPCM encoding algorithm, the recommended proposal from CCITT G. If 723 is used, an adaptation speed control circuit can be applied to the speed control calculation circuit 34 of the present invention, and a scaler scale factor adaptation circuit can be applied to the scale factor calculation circuit.

As the decoding circuit of the PCM / ADPCM encoding / decoding circuits 18 and 19 of the present invention, the circuit on the lower side of FIG. 2 can be applied. In FIG. 2, 40 is ADPC
M signal input terminal, 41 ADPCM decoding circuit, 42 external coding bit number control signal input terminal, 43 bit number determining circuit, 44 coded bit number control signal line, and 45 P
The CM signal output terminal is shown.

Next, the above circuit will be described. In the ADPCM decoding circuit 41, the ADPCM signal input from the format conversion circuit 17 is supplied to the ADP in accordance with the coded bit number control signal line 44 output from the bit number determination circuit 43.
The PCM signal is code-converted with the number of coded bits of the CM coding algorithm and output to the format conversion circuit 17.

In the bit number determination circuit 43, when the above-mentioned coded bit number information input from the external coded bit number control signal input terminal 42 indicates that there is data, the data optimum coded bit number (5 bits) is set. The requested signal,
In addition, at other times, the number of audio coding bits (3 bits)
Is output to the ADPCM encoding circuit 32 using the encoding bit number control signal line 44.

[0033]

As described above, the present invention is capable of transmitting voice signals and modem signals in the voice band (including G3 facsimile signals) without any problems, and has no problem of facing other manufacturers. Can be provided by a transcoder.

Further, the presence or absence of the data signal is determined by comparing the scale factor, which follows the variance of the input signal sensitively, with a predetermined threshold value.
Since the determination can be performed in real time and a part of the blocks of the ADPCM encoding algorithm can be shared, an automatic variable bit type ADPCM encoder can be realized by adding a simple circuit.

[Brief description of drawings]

FIG. 1 is a schematic lock diagram of the basic configuration of a variable bit type ADPCM transcoder of the present invention.

FIG. 2 is a diagram showing an embodiment of a circuit of a variable bit type ADPCM transcoder of the present invention.

FIG. 3 is a diagram showing a frame structure of a 2M PCM signal.

FIG. 4 is a diagram showing an example of a frame structure of a 2M PCM signal according to the present invention.

FIG. 5 is a diagram showing a configuration of a time slot 0 of a 2M PCM signal.

FIG. 6 is a diagram showing an example of a time slot 0 of a 2M PCM signal according to the present invention.

[Explanation of symbols]

 11, 12 PCM input terminal 13, 14 PCM output terminal 15, 16 PCM line interface circuit 17 format conversion circuit 18, 19 encoding / decoding circuit 20 ADPCM line interface circuit 21, 22 ADPCM output terminal 32 ADPCM encoding circuit 34 speed Control calculation circuit 35 Scale factor calculation circuit 36 Judgment circuit 37 Bit number determination circuit 41 ADPCM decoding circuit 43 Bit number determination circuit

[Procedure amendment]

[Submission date] June 8, 1992

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

[0005]

An ADPCM transcoder for performing mutual code conversion between two 2M system PCM primary group signals and one ADPCM primary group signal, in which a PCM signal is input and the number of encoded bits is controlled. AD controlled by signal
An ADPCM encoding circuit that outputs a PCM signal and this A
A speed control calculation circuit for inputting a DPCM signal, controlling a scale factor, and calculating and outputting a first-order linear combination coefficient of the scale factor;
Enter the M signal is controlled by the first-order linear coupling coefficient, to calculate the scale factor calculated by the sound optimal for scale factor, the data optimum for scale factor, and these of the first-order linear coupling, the data optimum A scale factor calculation circuit for outputting the scale factor for use to the next stage and sending the calculated scale factor as the scale factor to the speed control calculation circuit,
A determination circuit for determining the presence or absence of data by comparing the output data optimization scale factor with a predetermined threshold value, and the determination result of the determination circuit is determined according to whether there is data or no data. A bit number determining circuit for issuing a coded bit number control signal, and the ADP
A transmission section having a format conversion circuit that rearranges the CM signal into a predetermined frame configuration based on the bit number control signal, and a predetermined bit number control signal for determining the bit number from the received signal. Format conversion circuit for returning to the signal format, a bit number determination circuit for extracting the number of bits returned to the predetermined signal format by this format conversion circuit and outputting a bit number control signal, and the output bit number A variable bit type ADPCM transcoder, characterized in that it comprises a receiving section provided with an ADPCM decoding circuit which makes the number of decoding bits variable based on a control signal. Further, according to the present invention, as an ADPCM encoding algorithm, a proposal G.G. from the International Telegraph and Telephone Consultative Committee (hereinafter abbreviated as CCITT). 723 is selected, and it is determined whether the input signal is a voice signal or a voice band modem signal according to the size of the scale factor in the ADPCM coding algorithm. Variable-bit type ADPCM of the preceding paragraph, characterized in that 5-bit encoding is assigned to each band modem signal.
A transcoder is obtained. Further according to the invention, A
As a time slot of a multiplexing frame of a DPCM signal, CCITT Recommendation G. A variable bit ADPCM transcoder of the preceding paragraph, characterized in that it transmits information on the number of coded bits of each channel using 761 timeslot 0, that is, whether it is a voice signal or a modem signal, to the opposite station. Be done.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of a basic configuration of a variable bit type ADPCM transcoder of the present invention, and 11 and 12 are 2M PCM.
Signal input terminals, 13 and 14 are 2M PCM signal output terminals, 15 and 16 are PCM line interface circuits, 1
7 is a format conversion circuit, 18 and 19 are PCM / AD
PCM encoding / decoding circuit, 20 ADPCM line interface circuit, 21 2M ADPCM signal output terminal
Child, 22 is 2M ADPCM signal input terminal.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

Next, this circuit will be described with reference to the drawings. AD
In the PCM encoding circuit 32, the format conversion circuit 17
The PCM signal input from AD is used as the number of encoded bits of the ADPCM encoding algorithm according to the signal of the encoded bit number control signal line 38 output from the bit number determination circuit 37.
The code is converted into a PCM signal and sent to the speed control calculation circuit 34 and the scale factor calculation circuit 35 .
At the same time, the format conversion circuit 17 outputs.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

In the bit number determination circuit 43, when the above-mentioned coded bit number information input from the external coded bit number control signal input terminal 42 indicates that there is data, the data optimum coded bit number (5 bits) is set. The requested signal,
In addition, at other times, the number of audio coding bits (3 bits)
A signal for requesting using coded bit number control signal line 44 and outputs the ADPCM decrypt circuit 41.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

1 is a schematic block diagram of the basic configuration of a variable bit type ADPCM transcoder of the present invention.

FIG. 2 is a diagram showing an embodiment of a circuit of a variable bit type ADPCM transcoder of the present invention.

FIG. 3 is a diagram showing a frame structure of a 2M PCM signal.

FIG. 4 is a diagram showing an example of a frame structure of a 2M PCM signal according to the present invention.

FIG. 5 is a diagram showing a configuration of a time slot 0 of a 2M PCM signal.

FIG. 6 is a diagram showing an example of a time slot 0 of a 2M PCM signal according to the present invention.

[Explanation of Codes] 11,12 PCM input terminal 13,14 PCM output terminal 15,16 PCM line interface circuit 17 format conversion circuit 18,19 encoding / decoding circuit 20 ADPCM line interface circuit 21 ADPCM output terminal 22 ADPCM input terminal 32 ADPCM encoding circuit 34 Speed control calculation circuit 35 Scale factor calculation circuit 36 Judgment circuit 37 Bit number determination circuit 41 ADPCM decoding circuit 43 Bit number determination circuit

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (3)

[Claims] 1. A 2M system PCM primary group signal and two ADPCs.
An ADPCM transcoder for performing mutual code conversion with one M1 order group signal, which inputs an PCM signal and outputs an ADPCM signal controlled by a coded bit number control signal, and the ADPCM signal , A speed control calculation circuit that controls the scale factor and calculates and outputs the first-order linear combination coefficient of the scale factor,
The ADPCM signal is input, a scale factor for speech optimization, a scale factor for data optimization, and a scale factor calculated by a linear combination of these are controlled by the first-order linear combination coefficient, and the data is calculated. A scale factor calculation circuit that outputs the optimum scale factor to the next stage and sends the calculated scale factor as the scale factor to the speed control calculation circuit, and the output data optimum scale factor is predetermined. A determination circuit for determining the presence or absence of data by comparing with a threshold value, and the number of bits for issuing a coded bit number control signal, which is determined according to whether the determination result of the determination circuit is with data or without data. A decision circuit and a predetermined circuit based on the bit number control signal for the ADPCM signal. And a format conversion circuit for rearranging the format conversion circuit, and a format conversion circuit for extracting a bit number control signal for determining the number of bits from the received signal and returning the signal to a predetermined signal format. A bit number determination circuit that extracts the number of bits returned to a predetermined signal format by the format conversion circuit and outputs a bit number control signal;
A variable bit type ADPCM transcoder, comprising: a receiving unit including an ADPCM decoding circuit that makes the number of decoding bits variable based on the output bit number control signal. 2. A proposal G.G. as an ADPCM encoding algorithm from the International Telegraph and Telephone Consultative Committee (hereinafter abbreviated as CCITT). 723 is selected, and it is determined whether the input signal is a voice signal or a voice band modem signal according to the size of the scale factor in the ADPCM coding algorithm. 5. The variable bit type ADP according to claim 1, wherein 5 bit coding is assigned to each band modem signal.
CM transcoder. 3. A CCITT recommendation G.264 as a time slot of a multiplexed frame of a 2M ADPCM signal. 2. The variable bit ADPCM transcoder according to claim 1, which transmits information on the number of coded bits of each channel using 761 timeslot 0, that is, whether it is a voice signal or a modem signal, to the opposite station.