JPH02276329A - Dsi device - Google Patents

Abstract

PURPOSE:To prevent an unnatural feeling to be given on a talker when the connection of a speech line is released by detecting a back ground noise included in hang-over time from received data on a PCM line. CONSTITUTION:A noise recording circuit 204 finds out the speech line whose connection with a relay line is just going to be released by allocation information, and outputs a speech signal of constant time detected just before cutoff successively and repeatedly to the speech line after its connection with the relay line is released. An output signal is inserted to the speech line whose connection is released by a noise insertion circuit 110. When a signal being detected just before the cutoff of the speech line is at least the one detected within the hang-over time of a voice detector used at the transmission of a DSI(digital speech interpolation) device, the background noise is inserted to a transmission side speech line to the speech line whose connection is released at a reception side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DSI (Digital Speech Interpolation) device used to improve the utilization efficiency of PCM telephone lines.

[Conventional technology]

On a line used for telephone calls, the ratio of the time during which voice energy exists to the time when the line is occupied is generally less than 40%, and if only the section where this voice energy exists is effectively transmitted, Information can be transmitted using the number N of relay lines, which is smaller than the number M of connected speech lines, and the utilization efficiency of the relay lines can be increased. This method is DS
It is called the I method and has been put to practical use as a DSI device in satellite lines and the like.

Generally, the transmitting side of a DSI device detects a section in a speech line where voice energy exists, connects the speech line and a relay line, and transfers this connection information (hereinafter referred to as communication path allocation information) to the relay line. via a dedicated time slot,
Communication path data is sent to the assigned relay line.

On the other hand, on the receiving side of the DSI, the allocation of trunk lines and call lines is determined based on the sent communication route allocation information, and the DSI
The communication path data sent from the transmitting side via the relay line is output to the communication line.

At this time, there are fewer relay lines than voice lines, so
There are always some telephone lines that are not connected to a relay line. Since such a line is completely silent and sounds unnatural during a telephone conversation, a very low level (not harsh) random noise is inserted into -a.

In addition, in recent years, the noise level that exists in the silent section of the communication line on the transmitting side is detected, the noise level is encoded and added to the channel assignment information, and the receiving side decodes the channel assignment information and also detects the noise level. A method in which the level is decoded and held, and when the connection between the speech line and the relay line is broken, random noise is inserted into the line according to the decoded noise level. Figure 2 (A) and (B) 1 is a block diagram showing an example of a conventional DSI device. In Figure 2, (A)
indicates the transmitting side, and (B) indicates the receiving side.

First, referring to FIG. 2A, on the transmitting side, PCM signals of M lines (the number of communication lines 2M is a positive integer) are inputted to the transmitting side input terminal 1a from the transmitting side communication lines. This input signal passes through the delay circuit 10a and is input to the transmission side high speed switch circuit 20a. Further, the PCM signal input to the transmission side input terminal 1a is input to the audio detector 30a which detects the presence of audio energy. This voice detector 30
One output of a is input to the transmitting side allocation control circuit 40a. One output of this voice detector 30a is input to a noise level detector 50a. The transmission side allocation control circuit 40a allocates the communication path according to the output of the voice detector 30a and sends communication path allocation information to the transmission side high speed switch circuit 20a and the allocation information encoder 60a. The noise level detector 50a detects the average value of the noise level for each line during the time when there is no voice energy on the input communication line, and the noise level detector 50a detects the average value of the noise level for each line.
Enter a. The allocation information encoder 60a encodes the communication path allocation information and the average level of noise of the communication line reflected in the communication path allocation information to create and output an allocation information code. The transmission side high-speed switch circuit 20a outputs N-line PCM signals corresponding to the number of relay lines N (N<M) according to the call path allocation information, and these N-line PCM signals are output from the allocation information encoder 60a. It is sent out from the output terminal 2a to the trunk line together with the allocation information code.

On the other hand, referring to FIG. 2(B), on the receiving side, the above N
The line PCM signal and allocation information code are input from the relay line to the receiving side input terminal 3a. Among these, the PCM signal of N lines is input to the receiving side high-speed switch circuit 90a, and at the same time, the assignment information code is input to the assignment information decoder 70a. decoded to the average noise level of the line. Based on this decoded channel assignment information, the receiving side assignment control memory 80a
is controlled, and the receiving side allocation control memory 80a transfers the allocation control information to the receiving side high speed switch circuit 90a and the noise insertion circuit 11.
Enter in 0a. The output of the receiving-side high-speed switch circuit 90a is given to the noise insertion circuit 110a as an M-line PCM signal. Furthermore, the average noise level decoded by the allocation information decoder 70a is determined by the random noise generator 100.
a, the random noise generator 100a generates random noise according to this average noise level for each unconnected communication path, and inputs it to the noise insertion circuit 110a. The noise insertion circuit 110a refers to the allocation control information and inserts random noise into speech lines to which no trunk lines are allocated. The output of this noise insertion circuit 110a is sent from the receiving side output terminal 4a to the receiving side communication line as a PCM signal of the M line.

In this way, in the DSI device, the communication lines on the transmitting side and the receiving side are set according to the communication path allocation information determined on the transmitting side. Furthermore, the voice detector is the most important part of the DSI device's channel assignment control.

The voice detector will be briefly described below.

Typically, a voice detector on the transmitting side of a DSI device detects voice energy by integrating the signal level of the input speech circuit. If the voice detector determines that there is no voice energy due to the part, unnecessary voice disconnections will occur frequently and the clarity of the call will deteriorate.
A hangover period is provided to provide inertia to the audio detector. This hangover time is normally set to a value of about 150 milliseconds in consideration of the transmission of voice and exchange signals. The communication path assignment of the DSI device is performed based on the output of the voice detector, which includes the above-mentioned hangover time. However, in recent years, the introduction of G3 facsimile (hereinafter referred to as FAX) to telephone lines has become popular, and it has become necessary to pass G3 FAX signals through the telephone line input to the DSI device.

FIG. 3 shows the automatic communication procedure on the sending side and receiving side of G3 FAX using the two-way communication method. The transmission procedure of 03 FAX, which is a two-way communication method, will be explained below with reference to FIG. In FIG. 3, (A) shows a signal sent out by the transmitting side, and (B) shows a signal sent out by the receiving side (a signal that is received and received by the sending side). First, a paging signal 200 is sent from the transmitting side, and when the receiving side recognizes the paging signal 200, it returns a called station identification signal 201, an initial identification signal, and a transmission command signal 202 to the transmitting side. The transmitting side receives this called station identification signal 20.
1, an initial identification signal, and a transmission command signal 202, and after analyzing them, a reception command signal 203 is transmitted. Upon receiving the passive command signal 203, the receiving side sends a pre-message response signal 20.
4 is returned, and when this signal is received by the sending side, a facsimile message 205 is sent in the form of a packet from the sending side. On the receiving side, one A for each packet.
Two-way simultaneous communication is performed by sending a CK signal to the transmitting side. Based on this ACK signal, the sending side determines whether the FAX communication is normal or abnormal.

If it is determined to be abnormal, the corresponding packet is retransmitted.

When transmitting this G3 FAX signal using a DSI device, the DSI device is a method that transmits only the section where the voice energy of the input call line exists, as described above, so even if the input call line is a 03 FAX signal, It is assigned to a trunk line through the same process as normal input audio. In FIG. 3, the calling signal 200 is a signal of 1100 Hz.
, is output for 5 seconds and has a pause time of 3 seconds. There is an interval of about 14 seconds from the last call signal 200 on the transmitting side until the reception command signal 203 is sent, and the reception command signal 203
There is an interval of approximately 1 second between when the facsimile message signal 205 is output and when the facsimile message signal 205 is output.

[Problem to be solved by the invention]

The conventional DSI device described above encodes the average noise level detected on the transmitting side and sends it to the receiving side of the DSI device using a part of the relay line, so the relay line cannot be used effectively. Since the noise added on the receiving side is random noise, it has the disadvantage that it gives an unnatural feeling to the speaker when the communication line is disconnected.

Also, if the voice presence rate of the input call line increases and approaches the capacity of the relay line, the above-mentioned G3 FAX calling signal 2
00 is assigned to the relay line and reaches the receiving side, but the call signal 200 and reception command signal 203 or reception command signal 2
03 and the facsimile message signal 205,
This is longer than the hangover time (150 milliseconds) of the voice detector of a normal DSI device, so the receive command signal 2
03 or facsimile message signal 205 to the relay line is delayed, normal data cannot be sent, FAX transmission errors occur, and the FAX playback screen becomes unclear. Further, as shown in FIG. 2, it includes a data delay circuit 10a for compensating the time for performing line allocation control, and when the transmission of the facsimile message signal 205 starts, the FAX is completed using the two-way communication method.
When determining whether communication is normal or abnormal, there is a drawback that accurate determination becomes impossible if the delay time becomes large.

[Means to solve the problem]

The DSI device of the present invention includes a decoder that decodes and outputs information on call path assignments separated from relay line inputs having a number of lines N (N is a positive integer), and a memory that stores information from the decoder. This memory is controlled by the information stored in the memory and outputs M (M>N) communication lines from the relay line input, and the communication circuit is controlled by the information stored in the memory and the communication lines within the hangover time. It has a storage circuit for storing included background noise, and a noise insertion circuit for inserting the background noise into the communication line to which no communication path is assigned.

a signal detector that outputs a setting instruction signal for setting a hangover time for an input call line on which a facsimile procedure signal is detected and a switching control signal for switching a call path; a voice detector that outputs a time setting value; a call path allocation control circuit that outputs call path allocation information according to the set value;
It has a communication path switching circuit that outputs an output to the communication line without inserting a delay circuit according to the switching control signal, and a switch circuit that outputs an output from the communication path switching circuit in accordance with the assignment information.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1(A) and FIG. 1(B) are the first and second embodiments of the present invention.
It is a block diagram showing an example of.

In the receiving side circuit of the first embodiment shown in FIG. 1(A), relay PCM signals of N lines are inputted to the receiving side input terminal 3 from the relay line. Of these, the PCM signals of N lines are input to the receiving side high-speed switch circuit 90, and at the same time, the allocation information code in the trunk line is input to the allocation information decoder 70 and decoded into channel allocation information. The receiving side allocation control memory 80 is controlled by this decoded channel allocation information, and the receiving side allocation control memory 80 transfers the allocation control information to the receiving side high speed switch circuit 90, the noise storage circuit 204, and the noise insertion circuit 1.
10. The output of the receiving-side high-speed switch circuit 90 is given to the noise insertion circuit 110 and the noise storage circuit 204 as an M-line PCM signal. The output of the noise storage circuit 204 is input to the noise insertion circuit 110.
10 inserts random noise into a communication line to which no communication path allocation has been performed while referring to the output of the receiving side allocation control memory 80. The output of this noise insertion circuit 110 is sent from the receiving side output terminal 4 to the receiving side communication line as a PCM signal of the M line.

Generally, a voice detector on the transmitting side of a DSI device detects voice energy by integrating the signal level of the input speech line. If the voice detector determines that there is no voice energy due to a short low level, it will cause unnecessary voice disconnections and reduce the intelligibility of the call.
A hangover period is provided to provide inertia to the audio detector. This hangover time is normally set to a value of 100 milliseconds or more in consideration of the transmission of voice and exchange signals. Therefore, to the receiving side of the DSI value, the N-line PCM signal with the hangover time always added immediately after the conversation is sent via the relay line, and even after passing through the receiving side high-speed switch circuit, there is no hang-up. Overtime is included in the call line. Therefore, the bankover time always exists immediately before the connection between the trunk line of the DSI device and the speech line is disconnected, and the PCM data on the speech line that exists during the hangover time is almost equal to the background noise on the transmitting side. .

The noise storage circuit 204 of the first embodiment receives and operates the M-line speech lines outputted from the receiving side high speed switch circuit 90 and the allocation control information outputted from the receiving side allocation control memory 80. The feature of its operation is that it continues to hold the PCM signal of the communication line for a certain period of time.Moreover, the noise storage circuit 204 also constantly refers to the allocation control information, and the noise storage circuit 204 also constantly refers to the allocation control information, so that the connection with the trunk line is determined by the allocation control information. The call line that is about to be disconnected is found, and the call signal detected for a certain period of time immediately before the call line is disconnected is retained, and the call signal detected even after the call line is disconnected from the relay line is applicable. It is configured so that it is continuously and repeatedly output to the telephone line. This output signal is inserted by the noise insertion circuit 110 into the disconnected speech line.

Here, if the signal detected immediately before the above-mentioned call line is disconnected is detected at least within the hangover time of the voice detector used on the transmitting side of the DSI device, it will be input to the transmitting side. This is approximately equivalent to the average level of background noise included in the call line on the receiving side, so the background noise included on the call line on the sending side will be inserted into the disconnected call line on the receiving side. .

In the transmission side circuit of the second embodiment shown in FIG. 1(B), the transmission side input terminal 1 receives the speech PCM signal of M (the number of speech lines) lines from the transmission side speech line. The PCM input signal of the M line passes through the communication path switching circuit 150 and is input to the transmission side high speed switch circuit 20 via the delay circuit 10 which normally compensates for the delay time in determining the allocation of the DSI device.

Further, the PCM signal input to the transmitting side input terminal 1 is inputted to the voice detector 30 which detects the presence of voice energy, and at the same time is inputted to the signal detector 120 which detects the transmitting side calling signal of G3 FAX. This voice detector 3
The output of 0 is input to the transmitting side allocation control circuit 40. The transmitting side assignment control circuit 40 stores line assignment information for the telephone line and the relay line, determines new telephone route assignment according to the output of the voice detector 30, and transfers the telephone route assignment information to the transmitting side high speed switch circuit. 20 and the allocation information encoder 60. The allocation information encoder 60 encodes the channel allocation information, creates an allocation information code, and outputs it. The transmitting side high-speed switch circuit 20 outputs PCM signals of N lines corresponding to the number of relay lines N (N<M) according to the communication path allocation information, and outputs PCM signals of N lines corresponding to the number of relay lines N (N<M), and
The M signal and the allocation information code output from the allocation information encoder 60 are sent from the output terminal 2 to the trunk line.

On the other hand, the signal detector 120 constantly monitors the FAX transmission control procedure signal on the input call line, and
3 When a FAX calling signal (calling signal 200 in FIG. 3) is detected, a hangover control signal 101 is sent to the voice detector 30, and at the same time a call path switching control signal 102 is sent to the calling path switching circuit 150. do. The hangover control signal 101 and the call path switching control signal 102 have information for each call line, and when the voice detector 30 receives the hangover control signal 101, it selects the call line specified by the hangover control signal 101. Extends the hangover time to several tens of seconds (usually about 15 seconds).

Additionally, since the output of the voice detector 30 usually includes a hangover time, if such a circuit is configured, when the G3 FAX signal shown in FIG. When connected to the relay line that received the G3 FAX transmission signal, it can be transmitted without interruption. That is, the telephone line that has detected the G3 FAX calling signal is connected to the relay line until it detects the line disconnection command signal 207 of FIG. 3 that restores the call from the G3 FAX. On the other hand, the communication path switching circuit 1
When 50 receives the call path switching control signal 102, it directly switches the call line to the G3 FA without going through the delay circuit 10.
The transmission signal of X is input to the transmission side high speed switch circuit 20. This is possible because once the G3 FAX transmission signal is connected to the relay line, it will not be cut off midway, and there is no need to compensate for the time required to newly determine line allocation. As a result, the delay time of FAX communication can be reduced as a DSI device, and it becomes possible to accurately determine whether FAX communication is normal or abnormal using a two-way communication method.

〔Effect of the invention〕

As explained above, the present invention does not send information regarding noise during no calls from the transmitting side of the DSI device to the receiving side, and only on the receiving side of the DSI device can detect hangovers from received PCM line data. By detecting the background noise included in the time, there is an effect that background noise that is approximately equal to the noise included in the transmitting side communication line can be applied to the receiving side communication line that is not connected by DSI operation.

In addition, by installing a G3 FAX procedure signal detector in the transmitting circuit and controlling the hangover time of the voice detector, even when the voice rate of the input call line increases, the G3
3. The FAX signal can be transmitted smoothly without being interrupted during transmission, and the delay time can be shortened, so that G3 FAX communication using the two-way communication method can be performed normally.

1... Sending side input terminal, 2... Sending side output terminal, 3
... Receiving side input terminal, 4... Receiving side output terminal, 10
...delay circuit, 20...transmission side high-speed switch circuit,
30... Voice detector, 40... Transmission side allocation control circuit, 50a... Noise level detector, 60... Allocation information encoder, 70... Allocation information decoder, 80... Reception side allocation control memory, 90...receiving side high speed switch circuit;
100a... Random noise generator, 101... Hangover control signal, 102... Call path switching control signal, 110... Noise insertion circuit, 120... Signal detection circuit, 150... Call path switching circuit.

Claims (2)

[Claims] (1) A decoder that decodes and outputs the information on call path assignments separated from the trunk line input of the number of lines N (N is a positive integer), a memory that stores the information from this decoder, and this memory that stores the information. The number of lines M from the relay line input is controlled by the information of
a switch circuit that outputs (M>N) speech lines; a storage circuit that stores background noise included in the hangover time by the information stored in the memory and the speech lines;
A DSI device comprising: a noise insertion circuit that inserts the background noise into the communication line to which no communication path is assigned. (2) a signal detector that outputs a setting instruction signal for setting the hangover time of the input call line on which the facsimile procedure signal is detected and a switching control signal for switching the call route;
a voice detector that outputs a hangover time set value preset by the setting instruction signal; a call path assignment control circuit that outputs call path allocation information according to the set value; D according to claim (1), further comprising: a communication path switching circuit that outputs an output without inserting a delay circuit; and a switch circuit that outputs an output from the communication path switching circuit according to the allocation information.
SI device.