JPH0630141A - Voice compression transmitter - Google Patents

Abstract

PURPOSE:To allow the voice compression transmitter to transmit a signal subject to voice coding at a low bit rate and a demodulated signal for MODEM or a facsimile equipment or the like independently of models of exchanges in an in-enterprise network with respect to provided between an exchange and a relay line through which a code signal at a low speed resulting from a compressed signal at a usual voice coding speed is sent. CONSTITUTION:The transmitter is provided with a frame addition section 2 inserting a specific frame synchronizing signal to an input signal from a relay line to an exchange 11 and with a frame detection section 3 detecting the specific frame synchronizing signal from an output signal to the relay line in pairs with the input signal, and also with switches 4a-4d implementing the control such that a low speed code signal is transmitted to a relay exchange and a relay line when the frame detection section 3 detects the synchronizing signal, and a decoded voice signal is transmitted to the relay exchange and a compressed low speed code signal is transmitted to the relay line when the detection section 3 does not detect the synchronizing signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice compression / transmission apparatus for transmitting / receiving a voice coded signal or a demodulated signal such as a modem facsimile.

With the recent progress of voice compression technology, it is desired to perform voice transmission at a low bit rate in a corporate network to effectively use a transmission line. Further, with the spread of personal computer communication and facsimile, it is required to demodulate these signals and transmit them at a low bit rate.

[0003]

2. Description of the Related Art Conventionally, a voice signal is digitized to 64 Kb on a transmission line of a relay line connecting exchanges.
It is designed to transmit in the ps band, but in the case of a compression rate of about 32 Kbps (ADPCM), which is half of that, in the case of passing through an intermediate exchange on the way, the original 64 Kb
The operation of decompressing (decoding) to ps and compressing it again when outputting it to the transmission line is performed.
Since there is no problem in sound quality even after repeated expansion, transmission at this compression rate is used.

However, due to the progress of compression technology and effective transmission of signals to be transmitted through a limited transmission line, 32K
A method of compressing at a compression rate of bps or less, for example, 16 Kbps and transmitting is adopted. The same is also desired when the signal of a modem, a facsimile, etc. is terminated by modulation / demodulation and transmitted. That is, for example, 96
When modulating 00bps data with a modem and transmitting it as an analog signal (a signal modulated by amplitude modulation / phase modulation, etc.), if it is converted into PCM and transmitted as a 64Kbps digital signal, an excessive band is used.
It is desired to demodulate (modulate) to bps, transmit at a low bit rate, and demodulate on the receiving side.

However, a signal of 64 Kbps is converted to 16 Kb.
When compressed to ps and transmitted, there is a problem that sound quality deteriorates when a process of decoding (expanding) for relay exchange in the middle of transmission and further compressing is repeated. A conventional method for avoiding this is shown in the explanatory view of the conventional example in FIG.

FIG. 9 shows a compression rate from 64 Kbps to 16
This is an example of reducing to Kbps (compressed to 1/4).
Reference numeral 90 is a transmission device provided between the trunk line and the exchange and having a coding / decoding function for compression / expansion, and 95 is a relay exchange (TS) 96 accommodating the relay line and a subscriber accommodating the subscriber. An exchange equipped with a private branch exchange (LS) 97, and 98 is a subscriber telephone.

In this conventional example, 16 Kbps is provided on the trunk line.
When the signal a compressed to is transmitted and the transmission path has a bandwidth of 64 Kbps, four multiplexing can be performed. This 16Kb
When the ps signal a is input to the transmission device 90, the exchange 95
To convert to 64 Kbps, which is the exchange unit in
A dummy bit is added in the bit addition unit 92.

The signal b having a bit length of 64 Kbps in this way is exchanged in the repeater exchange 96. In the switching operation, the call is connected to the output line depending on whether the destination of the call is a relay call to another area or a call arriving at the subscriber exchange of the exchange 95 (call dropped by the own station). All of these output lines are input to the transmission device 90.

In the case of a call output to a trunk line to another station,
The signal on the output line from the repeater exchange 96 (the signal structure is the same as that of the above-mentioned b) is returned to the original compressed signal c of 16 Kbps by removing the bit added by the bit adding section 92 in the bit removing section 93. And output to the trunk line. In the case of a call dropped by the local station, the signal appearing on the output line from the repeater exchange 96 (the signal configuration is the same as that of b) is bit-removed by the bit removing unit 93 and the original compression code 1
The signal d of 6 Kbps is restored, and then the decoding unit 94 decodes the compression code of 16 Kbps to the original 64 Kbps. This 64 Kbps signal is input from the transmission device 90 to the subscriber exchange 97, and an exchange operation is performed so as to connect to the destination subscriber telephone 98.

In the case of 32 Kbps compression, it is not necessary to provide the above-mentioned transmission device, and bit addition or
32 Kbps to 64 Kbp without bit deletion
Decrypt to s, input to the exchange and exchange at 64 Kbps,
Relay or drop your own station.

[0011]

As described above, 64
When a low bit rate voice code such as a Kbps signal compressed into a 16 Kbps code or a signal such as a modem / facsimile is terminated by modulation / demodulation and transmitted,
Special coordination needs to be made between the exchange and the transmission equipment. For this reason, there is a problem that it is difficult to introduce a low bit rate compression technique not only in the public network but also in the corporate network because the types of transit exchanges that can be used are limited.

The present invention is provided in a corporate network or the like between a switching line and a switching line for transmitting a low bit rate voice-encoded signal, a demodulated modem, a facsimile signal, etc., regardless of the type of switching system. It is an object of the present invention to provide a voice compression transmission device.

[0013]

FIG. 1 is a block diagram showing the principle of the present invention, and FIG. 2 is an explanatory view of its operation. Reference numeral 1 in FIG. 1 is a compression transmission apparatus according to the present invention, which is provided at any position in the transmission apparatus or between the relay line and the exchange, and shows a structure corresponding to one transmission line and one reception line. Reference numeral 2 is a frame addition means for adding a specific frame synchronization signal for identifying whether it is a relay call or a local station dropped call to the input signal, and 3 is a frame for detecting the specific frame synchronization signal and controlling each of the switches 4a-4d. Detecting means, 4a and 4b are first switches, and 4b and 4d are second switches
Switch, 5 is a PCM signal from the exchange (64 Kbp
s) is compressed to a low bit rate (eg 16 Kbps)
Audio encoding means for encoding to, a bit removing means for removing the bit (dummy bit) added by the bit adding means, and a PCM for the signal compressed to a low bit rate to the original PCM.
A voice decoding means for decoding a signal (64 Kbps), 8 is a bit adding means for adding a bit (dummy bit) to a low bit rate compressed signal to formally form a signal of 64 Kbps, 9a and 9b are one line of a relay line The receiving lines and transmitting lines, 10a and 10b, which constitute the above, are a receiving line and a transmitting line in one line connecting the compression transmission device and the exchange, and 11 is an exchange. The frame synchronization signal is represented by inserting a specific bit pattern in a plurality of consecutive frames.

According to the present invention, a relay call or a local station dropped call is assigned corresponding to a line, a frame synchronization signal is added to a received signal in the case of a relay call, and a frame synchronization signal is added in the case of a local station dropped call. In the case of a relay call, the transmitting side detects the frame synchronization signal and switches each switch to add bits to the received signal and remove bits from the transmitted signal. In the case of own station drop, the received signal is decoded and the transmitted signal is compression-coded.

[0015]

In FIG. 1, one relay line connected to the compression transmission apparatus 1 (including one channel signal of multiplexed signal)
Is used for a call dropped by the local station, a control signal is set by the control unit (not shown) so as not to drive the frame addition means 2. In this case, since the frame detecting means 3 of the compression transmitting apparatus 1 inputs the signal from the subscriber side of its own station from the exchange 11, the frame synchronizing signal added by the frame adding means 2 cannot be detected and therefore the first switches 4a, 4b. And the second
The switches 4c and 4d are set to be switched to their respective sides.

The state at this time is shown in FIG. Shown in. In this state, the compressed signal from the receiving line 9a is decoded by the voice decoding means 7 and becomes a PCM signal of 64 Kbps, which is input to the exchange 11 and sent to the subscriber in the own station via the exchange.
The signal from the subscriber is encoded by the voice encoding means 5 in the compression transmission apparatus 1 from the exchange 11 into a compression code of 16 Kbps and sent to the transmission line 9b.

Next, when the line connected to the compression transmission apparatus 1 is used for a relay call from this exchange 11 to another exchange,
A control signal is set by the control unit (not shown) to drive the frame adding means 2, and the frame adding means 2 adds a frame synchronization signal to the received signal. on the other hand,
Since this is a relay exchange, the compression transmission device 1 to the exchange 11
It is connected to the transmission device of the trunk line that goes to another exchange via the. The compressed transmission device 1 '(FIG. 2B.
The frame synchronization signal is added by the frame addition means 2 in the compression transmission apparatus 1 ', and the signal added with the frame synchronization signal is sent from the exchange 11 to the frame detection means 3 of the compression transmission apparatus 1. When input, a frame synchronization signal is detected and the first and second switches 4a to 4d are switched to the contact side.

In the other compression transmission device 1 ', the compression transmission device 1
The frame synchronization signal added at is detected, and the first and second switches are similarly switched to. This state is shown in Figure 2.
B. Shown in. B. of FIG. , Reference numerals 2 ', 3' ... Represent the same components as the reference numerals 2, 3 ... In FIG. 1 provided in the compression transmission apparatus 1 '.

Referring to FIG. In the compression transmission device 1 and the compression transmission device 1 ′, the switches 4a to 4d are similarly switched to the contacts, and the compression signal of the reception line 9a input to the compression transmission device 1 is converted into dummy bits by the bit addition means 8. The frame synchronization signal is added, and further the frame synchronization signal is added by the frame adding means 2 and is input to the exchange 11. This signal is exchanged, and the compression transmission device 1'of the trunk line that goes to another exchange.
When it is input to, the frame detection signal is detected by the frame detection means 3 ', the dummy bits are removed by the bit removal means 6', the original compressed signal is restored, and the compressed signal is output to the transmission line 9b '. The compressed signal input to the reception line 9a 'of the compression transmission device 1'is similarly routed in the opposite direction to the bit addition, frame addition, and bit removal processing, and then output from the transmission line 9b of the compression transmission device 1'. To be done.

As described above, the compressed signal can be connected without performing complicated processing for both the relay call and the local station dropped call.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 3 is a structural example of a switching network in which the present invention is implemented. FIG. 4 is a block diagram of an embodiment of the compression transmission apparatus, FIG. 5 is an example of each signal format, FIG. 6 is a connection state in the case of a local station dropped call, and FIG. 7 is a connection state in the case of a relay call.

In FIG. 3, 30a to 30c are exchanges in different areas, 31a to 31c are transmission devices provided between the exchanges and the trunk lines, and 32a to 32c are subscriber telephones accommodated in the exchanges. , 33 are transmission devices 3
1a and a transmission device 31b are high-speed digital lines which are relay lines, 33a and 33b are compression transmission devices provided in the transmission devices 31a and 31b connected to the high-speed digital line 33, and 34 is a transmission device 31b and a transmission device 31c. High-speed digital lines 34b and 34c, which are connecting lines, are transmission devices 31b and 3 connected to the high-speed digital line 34.
It is a compression transmission device provided in 1c.

The transmission devices 31a to 31c shown in FIG. 3 correspond to the respective high-speed digital lines, and the compression transmission devices 33a, 33b and 34 shown in FIG.
b and 34c are provided. The configuration of FIG. 4 corresponds to the configuration of FIG.

In FIG. 4, 40 to 46 are 2 in FIG.
~ 8, 40 is a frame addition unit, 41 is a frame detection unit, and 42a to 42d are switches (S
W1 to SW4) and 43 are 16K audio (64Kbps)
A voice encoding unit for compressing and encoding a bps signal, 44 is a bit removing unit for removing dummy bits, 45 is a voice decoding unit for decoding compression encoded voice signals, and 46 is a bit adding unit for adding dummy bits. is there.

FIG. 5 shows an example of the format of each signal.
In this example, 16 Kbps is obtained by compressing a 64 Kbps digital signal obtained by converting the voice of one line into PCM on the trunk line.
This is an example of transmission with a signal of, and is transmitted with each frame of one line (one channel) in the time-division multiplexed line.
The Kbps signal is composed of 8 bits.

A and B in FIG. 5 are frame adding units 40 in FIG.
The format of the signal output from the A. Is the format of the received signal of the local station dropped call. In this case, since the frame synchronization signal is not added by the frame addition unit 40, the switches SW1 and SW2 are in the state of being switched to the upper side, and thus the signal input from the transmission line (16 Kbps).
Is decoded to 64 Kbps by the audio decoding unit 45, and A. It becomes an 8-bit signal like.

FIG. 5B. Is the format of the received signal of the relay call. In this case, since the frame detection unit 41 detects the frame, the switches SW1 and SW2 are switched to the lower side. Therefore, 16 Kb compressed from the transmission line
In the bit addition unit 46 for the ps signal D2 (2-bit signal), 6-bit dummy bits (indicated by "-" in the figure) are added to the lower portion of the signal bits to form a frame addition unit as an 8-bit signal. Enter 40. The frame adding unit 40 adds the frame bit (indicated by F) to the least significant bit of the 8-bit signal, and the B.B. A signal like is generated. The frame bits (F) are supplied so as to sequentially form a specific pattern for a plurality of frames. For example, the pattern 00110011 ... Is used.

In the example shown in FIG. 5, 16 Kbps are set on the trunk line.
This is an example of a signal compressed to s, but it may be compressed to another speed such as 8 Kbps, in which case 64 Kbps 8
One bit is compressed for each bit. Also, an example is shown in which 1 bit is added to each frame as a frame synchronization signal, but it is also possible to add 2 bits or more to form a frame synchronization signal.

C and D in FIG. 5 are the frame detector 41 in FIG.
Is the format of the signal input to C.I. Is a format of a transmission signal of a call dropped by the own station. In this case, 64
An 8-bit signal D1 of Kbps is supplied from the exchange. In this case, the frame sync signal is not added because it is a local station dropped call, so the switches SW3 and SW4 are in the state of being switched to the upper side, and the voice coding unit 43 sets 16
It is compressed into a Kbps signal and output to the transmission line.

D. Is a format of a transmission signal in the case of a relay call, in which a dummy bit is added to the compressed 16 Kbps signal D2 and a frame synchronization signal (indicated by F) is added to the least significant bit. When the pattern of the frame synchronization signal is detected by the frame detection unit 41, all the switches SW1 to SW4 are switched to the lower side. Therefore, this D. Signal is input to the bit removing unit 44, dummy bits (6 bits including the bit F of the frame synchronization signal) are removed, and a 2-bit signal D2 is output.

FIGS. 6 and 7 show the connection state in the case of the local station dropped call and the connection state in the case of the relay call in the configuration of the switching network shown in FIG. In the case of FIG. 6, the connection is made when a call from the telephone 32a of the exchange 30a arrives at the telephone 32b of the exchange 30b to make a call. The voice signal (PCM signal of 64 Kbps) transmitted from 30a is compressed to 16 Kbps by the voice coding unit represented by in the compression transmission device 33a in the transmission device 31a and input to the transmission device 31b through the transmission line L2 of the relay line 33. Then, the original data is restored to 64 Kbps by the decryption unit shown here, and reaches the telephone set 32b through the exchange 30b. 64K transmitted from telephone 32b
The bps voice signal is transmitted to the compression transmission device 33 of the transmission device 31b.
In b, it is compressed to 16 Kbps by the voice encoding unit represented by and transmitted to the transmission line L1, and when received by the transmission device 31b, it is decoded into the original 64 Kbps by the voice decoding unit and is output to the telephone 32a via the exchange 30a. It

In the case of FIG. 7, the telephone 32a of the exchange 30a
Call originated from the relay station 30b is relayed to the exchange 30b.
This is a connection for making a call by connecting to the telephone 32c of c. In this case, the voice signal transmitted from 32a is compressed to 16 Kbps in the voice encoding unit of the transmission device 31a and input to the transmission device 31b through the transmission line L1 as in the case of FIG. Since this call is a relay call in the exchange 30b, it is connected to the bit addition section indicated by, dummy bits are added, relay exchange is performed in the exchange 30b, and the call is sent to the exchange in which the partner telephone is accommodated. Input to the compression transmission device 34b.

Here, the dummy bits are removed by the bit removing unit indicated by and the dummy bits are sent out to the transmission line L3 and input to the compression transmission device 34c of the partner transmission device 31c. In the exchange 30c, this call is a local station dropped call and is decoded by the voice decoding unit to a signal of 64 Kbps, and the telephone 32c
Sent to. The audio signal transmitted from 32c is subjected to the same processing through a route reverse to the above, and the transmission device 3
1c through the transmission line L4, the compression transmission device 34b, the exchange 30b, the compression transmission device 33b, the transmission line L1, and the compression transmission device 33a.

Configuration of the above embodiment (FIGS. 4, 7, and 8)
Shows an example in which a voice signal (voice compression signal) is transmitted on a relay line. However, when a modem (data) or a facsimile signal is also transmitted on the line together with a voice signal, the following FIG.
The configuration of another compression transmission device shown in FIG.

In FIG. 8, reference numerals 40 to 42, 44,
46 is the same component as the same code in FIG. 4, but the voice code / modulation section 43 ′ is composed of a voice code section 43a and a modulation 43b, and the decoding / demodulation section 45 ′ is a decoding section 45a and a demodulation section 4
5b is different. The voice encoding unit 43a and the voice decoding unit 45a therein perform encoding (compression) and decoding (expansion) according to the characteristics of the voice, and for modem and facsimile signals, the modulation unit 43b and the demodulation unit 45b.
Thus, PCM conversion and PCM decoding are performed.

Code / modulation section 43 'and decoding / demodulation section 45'
Each of them is provided with a changeover switch (not shown) inside and is switched to use either one. This Figure 8
When using the compression transmission device of
a is connected to the terminals of the switches S3 and SW4, and the audio decoding unit 45a is connected to the terminals of the switches SW1 and SW2. When data is sent and received between subscribers using a modem and a facsimile, a training signal for the modem and a facsimile is transmitted between the subscribers. Therefore, when the signal is detected by a compression transmission device (by some means), a voice code The change-over switches inside the modulator 43 'and the voice decoding / demodulator 45' are switched, the modulator 43b is connected to the terminals of the switch 3 and the switch 4, and the demodulator 45b is connected to the switch S.
Connected to the terminals of W1 and SW2, they perform modulation and demodulation operations for calls dropped by the local station, respectively.

In the above example, one voice encoding unit, one modulation unit, one voice decoding unit, and one demodulation unit are provided, but a plurality of units are provided corresponding to different functions (conversion speed, conversion characteristics, etc.), and frames are provided. By generating a plurality of mutually different patterns as the synchronization signal (also generated in the case of the own station call), it is possible to switch the device having the corresponding function.

[0038]

According to the present invention, compression / non-compression and modulation / demodulation / non-modulation of a voice signal in a repeater exchange can be judged by a compression transmission device, and since it does not depend on the exchange, voice transmission at a low bit rate is used. It is possible to efficiently configure and operate the corporate network.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is an explanatory view of the operation of the present invention.

FIG. 3 is a block diagram of a switching network in which the present invention is implemented.

FIG. 4 is a configuration diagram of an embodiment of a compression transmission device.

FIG. 5 is an example of a format of each signal.

FIG. 6 shows a connection state in the case of a local station dropped call.

FIG. 7 is a connection state in the case of a relay call.

FIG. 8 is a configuration diagram of an embodiment of another compression transmission device.

FIG. 9 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 1 compression transmission device 2 frame adding means 3 frame detecting means 4a, 4b first switch 4c, 4d second switch 5 voice encoding means 6 bit removing means 7 voice decoding means 8 bit adding means 9a, 9b relay line receiving line , Transmission lines 10a, 10b reception line, transmission line 11 switch

Claims (6)

[Claims] 1. A voice compression transmission apparatus provided between a relay line and a switch, which transmits a signal at a normal voice coding rate by a compressed low-speed code signal, and specifies the input signal from the relay line to the switch. Frame adding means for inserting the frame synchronizing signal of the above, and frame detecting means for detecting a specific frame synchronizing signal from an output signal to a relay line paired with the above input signal, and the synchronizing signal is detected by the frame detecting means. When it detects, the low speed code signal is sent to the repeater exchange and the trunk line. When the sync signal is not detected, the decoded voice signal is sent to the repeater switch and the compressed low speed code signal is sent to the repeater line. A voice compression transmission device comprising a control switch. 2. The voice compression transmission apparatus according to claim 1, wherein the voice compression transmission device decodes a compressed signal input from a relay line into an original signal, and a bit length is a normal coding rate. A bit addition means for setting the bit length of the signal, a first switch for selecting one of the voice decoding means and the bit addition means, and a specific frame synchronization signal for the signal output from the switch when the signal is a relay call. A frame adding means driven to add a frame, and a frame detecting means for detecting the frame synchronizing signal with respect to a signal output from the exchange and output to a trunk line, and the output signal is encoded at a low speed. The audio encoding means, bit removing means for removing dummy bits from the output signal, and a second switch for selecting one of the audio encoding means and the bit removing means. When the over-time detection means for detecting a frame sync signal, audio compression transmission apparatus and performs switching of the first switch and second switch. 3. The voice according to claim 2, wherein the specific frame synchronization signal added by the frame adding means is composed of a pattern added to the least significant bit of the signal added by the bit adding means. Compressed transmission device. 4. A voice compression transmission device that modulates and demodulates an analog signal of a modem, a facsimile or the like connected to a public telephone line or a private branch exchange, and transmits the analog signal through the relay line, specifying the input signal from the relay line to the private branch exchange. Frame adding means for inserting the frame synchronizing signal of the above, and frame detecting means for detecting a specific frame synchronizing signal from an output signal to a relay line paired with the above input signal, and the synchronizing signal is detected by the frame detecting means. A voice compression transmission device comprising a switch controlled so as to transmit a demodulated signal to the exchange when detecting the signal, and to transmit a modulated PCM signal to the exchange when the synchronizing signal is not detected. 5. The voice compression transmission apparatus according to claim 4, wherein the compressed signal input from the relay line has a demodulation section for demodulating the input signal and a bit length is set to a bit length at a normal coding rate. Bit addition means, a first switch for selecting one of the voice demodulation means and the bit addition means, and a drive for adding a specific frame synchronization signal to the signal output from the switch when the signal is a relay call Frame detecting means for detecting the frame synchronization signal with respect to the signal output from the exchange and output to the relay line, a modulator for modulating the output signal, and a dummy bit from the output signal. And a second switch that selects one of the modulation unit and the bit removing unit, and the frame detecting unit detects a frame synchronization signal. That the speech compression transmission apparatus and performs switching of the first switch and second switch. 6. The voice decoding / demodulation unit according to claim 2, comprising a voice decoding unit for decoding the compressed signal input from the relay line into an original signal and a demodulation unit for demodulating the input signal into an analog signal. A bit addition means for making the bit length a bit length of a normal encoding speed, a first switch for selecting one of the voice decoding / demodulation section and the bit addition means, and a signal corresponding to the signal output from the switch. Is provided with a frame addition means that is driven so as to add a specific frame synchronization signal when a relay call is made, and a frame detection means that detects the frame synchronization signal from the signal output from the exchange and output to the relay line. A voice coding / modulating unit including a voice coding unit and a modulating unit for coding the output signal at a low speed, a bit removing unit for removing dummy bits from the output signal, the coding unit and the bit unit. A second switch that selects one of the removing units, and when the frame detecting unit detects a frame synchronization signal, it switches between the first switch and the second switch, and the voice decoding / demodulation unit and the code / modulation unit. When the training signal of the modem / facsimile is detected on the input / output signal, the section drives the demodulation section and the modulation section respectively, and when the training signal is not detected, the speech decoding means, respectively.
An audio compression transmission device characterized in that a coding means is driven.