JPH0666750B2 - Frame signal system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention uses two 24-channel 1.544Mb / s PCM signals to 48-channel 1.544Mb / s adaptive differential PCM (hereinafter referred to as "ADPCM").
1.544Mb / sA of ADPCM device such as transcoder
The present invention relates to a frame signal system for DPCM signals.

[Conventional technology]

Conventionally, the frame signal system used for this type of device is
It is composed of 12 multi-frames or 24 multi-frames in order to steal and transmit the bit of each communication channel corresponding to the signaling information of each communication channel once every 6 frames. These 1 frames consist of 193 bits,
The sample rate is 8000Hz. In each frame, 48 speech channels of a voice signal encoded into a 4-bit ADPCM signal are multiplexed in a word configuration, and a 1-bit frame pulse for frame synchronization is further added to this to construct a 125 μs frame. .

In the case of 12 multiframes, the frame pulse is used for synchronization of odd frames and multiframe for even frames. For 24 multiframes, frame numbers 4,8,12,16,20,24 are used for multiframe synchronization, odd frames are used for data link bits, and frame numbers 2,6,10,14,18, 22 is used for the error detection bit.

[Problems to be solved by the invention]

In the frame signal system described above, bit information is always stolen every 6 frames because of transmission of signaling information. As a result, the audio signal cannot be encoded into a 4-bit 32Kb / s ADPCM signal, and a 3-bit 24Kb / sADPCM signal is generated once every 6 frames.
There is no choice but to encode the signal. As a result, there is a drawback that the call quality is significantly deteriorated.

[Means for solving problems]

In order to eliminate such drawbacks, the present invention comprises the first bit of three odd frames between each signaling frame of the 24 multi-frame signaling system in the 1.544 Mb / s adaptive differential PCM signal of the time division multiplex communication device. The 3 data link bits are used as signaling information change indication bits for 48 channels, and if the signaling information of all 48 channels to be transmitted is the same as the previously transmitted signaling information, the signaling information change indication bit is set as the first bit. This is displayed by setting it to a predetermined value of 1 and bit stealing of audio signals is prohibited, and 4 bits 32 Kb / s
Adaptive difference PCM signal is transmitted, and when the signaling information is different from the previously transmitted signaling information, the signaling information change indication bit is set to the second predetermined value, the audio signal is bit stolen, and 3 bits 24Kb / s adaptive difference The PCM signal is transmitted, and the receiving side detects 3 bits of the signaling information change indication bit, makes a majority decision, and decodes the audio signal and the signaling signal corresponding thereto.

[Action]

According to the present invention, 4 bits 32 Kb / s are used as compared with the method of always 3 bits 24 Kb / s ADPCM encoding at the time of signaling frame.
sADPCM coding increases, voice characteristics are improved, and signaling distortion is not deteriorated.

〔Example〕

Next, one embodiment of the frame signal system according to the present invention will be described with reference to the table. The frame in this embodiment is
It consists of 24 multi-frames as shown in the table. Among these, the multi-frame synchronization bit (bM) and the error detection bit (bE) are the same as the conventional 24 multi-frame signal. The signaling information change indication bit (bS) is located at the same frame number as the conventional data link bit.

In the case of the present embodiment, as shown in the table, the change of the signaling bit A for 48 channels is displayed by 3 bits of the signaling information change display bit ma, and the channel slot of the frame number "6" is controlled. When the signaling changes, bits 1 to 3 and bits 5 to 7 are assigned for voice (bA), and bits 4 and 8 are assigned for signaling (bSS) and encoded. If it does not change, allocate all for voice (bA).

Similarly, the signaling information change indication bit mb indicates the change of the signaling bit B, controls the channel slot of the frame number 12, the signaling information change indication bit mc indicates the change of the signaling bit C, and the frame number 18 The channel slot is controlled, the signaling information change indicating bit md indicates the change of the signaling bit D, and controls the channel slot of frame number 24.

Decoding detects each signaling information change indication bit,
This is performed by decoding the voice signal and signaling bit corresponding to this. In order to protect against an error in the transmission line, whether or not there is a change is indicated by "1" or "0" so that the majority of the signaling information change indication bits composed of 3 bits can be determined. By this, even if any one of the three bits is erroneous, it can be correctly decoded.

A block system of a system to which the method is applied is shown in FIG. On the transmission side of FIG. 1 (a), the audio signal input terminal TI1 is connected to the ADPCM coding circuit 1, and the ADPCM coding circuit 1 is connected to the multiplexing circuit 2. The signaling information input terminals TI2 to TI5 are respectively supplied to the signaling coding circuit 3, and the output of each signaling coding circuit 3 is the storage circuit 4 and the comparison circuit 5.
And the output of each storage circuit 4 to the comparison circuit 5, the output of each comparison circuit 5 to the signaling information change indication bit sending circuit 6, and the output of the signaling information change indication bit sending circuit 6 to the multiplexing circuit 2. 2 and the ADPCM encoding circuit 1, the output of the multiplexing circuit 2 is connected to the output signal terminal TO1.

On the receiving side in FIG. 1 (b), the input signal terminal TI6 is connected to the separation circuit 8, and the output of the separation circuit 8 is ADPC.
M composite circuit 7, signaling information change indication bit detection circuit 1
0 and signaling decoding circuit 9. The output of the ADPCM decoding circuit 7 is connected to the audio signal output terminal TO2, each output of the signaling information change indication bit detection circuit 10 is connected to the signaling decoding circuit 9, and the output of the signaling decoding circuit 9 is connected to the signaling information output terminals TO3 to TO6. .

Next, this method will be described in detail with reference to FIG. 1 and a table. First
On the transmission side in FIG. 2A, the ADPCM encoding circuit 1 normally converts the 48-channel audio input signal from the audio signal input terminal TI1 into a 4-bit 32 Kb / s ADPCM signal for each channel and inputs it to the multiplexing circuit 2. To do. The signaling coding circuit 3 codes the 48-channel signaling information A to D from the signaling information input terminals TI2 to TI5 and inputs it to the memory circuit 4, the comparison circuit 5 and the multiplexing circuit 2. The comparison circuit 5 compares the previously transmitted signaling input from the storage circuit 4 with the signaling to be transmitted to see if the state of the 48 channels has changed, and the result is signaled by the signaling information change indication bit transmission circuit 6 To enter. In response to this, the signaling information change indication bit sending circuit 6 adds a signal for controlling the frame corresponding to each signaling bit to the AD signal.
Input to the PCM coding circuit 1 and the multiplexing circuit 2.

For example, if signaling bit A changes, ADPCM
Encoding circuit 1 is 3 bits 24Kb / sA during frame number "6"
DPCM encoding is performed, and the multiplexing circuit 2 multiplexes signaling bits into bits 4 and 8. Further, the signaling information change indication bit ma3 bit of the frame numbers "1", "3", "5" is set to "1" which is the second predetermined value and sent to the output signal terminal TO1.

On the receiving side in FIG. 1 (b), the signal input from the input signal terminal TI6 is separated by the separation circuit 8 and input to the ADPCM decoding circuit 7, signaling decoding circuit 9 and signaling information change indication bit detection circuit 10. . The signaling information change indication bit detection circuit 10 detects the signaling information change indication bit ma3 bit, makes a majority decision, and inputs the result to the ADPCM decoding circuit 7 and the signaling decoding circuit 9. In the case of the above example, the signaling information change indication bit ma3 of the frame numbers “1”, “3”, “5”
When the bit "1" is detected, the ADPCM decoding circuit 7 performs 3-bit 24 Kb / s ADPCM decoding during the frame number "6". Further, the signaling decoding circuit 9 rewrites the signaling information.

When the signaling bit A does not change, the ADPCM coding circuit 1 performs 4-bit 32Kb / s ADPCM coding even during the frame number "6" on the transmitting side of FIG. In 2, the stealing of signaling bits is prohibited, the signaling information change indication bit ma3 of frame numbers 1, 3, and 5 is set to "0" which is the first predetermined value, and the signal is sent to the output signal terminal TO1.

On the receiving side of FIG. 1 (b), the ma bit "0" of the signaling information change indication bit is detected and ADPCM is detected.
Decoding circuit 7 is 4 bits 32Kb / sA even during frame number "6"
Performs DPCM decoding. Further, rewriting of the signaling decoding circuit 9 is prohibited.

〔The invention's effect〕

As described above, according to the present invention, the 3-bit data ring bit is used as the signaling information change indication bit for 48 channels, so that the 4-bit 32 Kb / sA method is always used in the signaling frame.
The number of cases of DPCM coding is increased, the voice characteristics are improved, and the signaling distortion is not deteriorated. Further, the change information is protected against errors because the majority decision is made using 3 bits.

[Brief description of drawings]

1 (a) and 1 (b) are block system diagrams showing a system to which an embodiment of a frame signal system according to the present invention is applied. 1 ... ADPCM coding circuit, 2 ... Multiplexing circuit, 3 ... Signaling coding circuit, 4 ... Storage circuit, 5 ... Comparison circuit, 6 ... Signaling information change indication bit sending circuit,
7 ... ADPCM decoding circuit, 8 ... Separation circuit, 9 ... Signaling decoding circuit, 10 ... Signaling information change indication bit detection circuit, TI1 ... Voice signal input terminal, TI2-TI5 ...
Signaling information input terminal, TI6 ... Input signal terminal, TO1
…… Output signal terminal, TO2 …… Audio signal output terminal, TO3 to TO
6 …… Signaling information output terminal.

Claims (1)

[Claims] 1. A 3-bit data link bit consisting of the first bit of three odd frames between 48 signaling frames of a 24-multiframe signaling system in a 1.544 Mb / s adaptive differential PCM signal of a time division multiplex communication device. The signaling information change indication bits for channels are set, and on the transmitting side, if the signaling information of all 48 channels to be transmitted is the same as the previously transmitted signaling information, the signaling information change indication bits are set to a first predetermined value. This is displayed, bit stealing of the audio signal is prohibited, the 4-bit 32Kb / s adaptive differential PCM signal is transmitted, and if the signaling information is different from the previously transmitted signaling information, the signaling information change indication bit is Set to a predetermined value of 2, steal the audio signal, and send it as a 3-bit 24Kb / s adaptive differential PCM signal. The performed, on the receiving side, a frame signal format to detect three bits of signaling information change indicator bits determined majority, and performs decoding of audio signals and signaling signals corresponding thereto.