RU2127025C1 - Digital commutation system - Google Patents

Abstract

FIELD: communication devices. SUBSTANCE: invention discloses design of automatic exchange system with user equipment providing possibility to connect analog and digital channels and heterogeneous subscriber lines. Each subscriber assembly is connected to separate exchange unit of subscriber line. Switching unit provides commutation of digital channels, analog channels, shared system channels. Subscriber assembly provides independent exchange of data and telephone information through subscriber line channel-sharing system. Best voice quality is achieved by means of voice- processing unit installed in subscriber assembly and, when connection being established, maximal possible rate is chosen constrained by capabilities of signal processing circuits and digital or analog channels which are connected to switching unit. Rate value is input by operator of input-output unit into initialization data storage unit when network is developed, or its structure is upgraded. In the course of establishing connection this value may be corrected using results of testing all pieces of connection path by means of test signal messages. After testing, marker selects maximal possible rate which is allowed by channel and subscriber equipment. Exchange of system information on all pieces of connection path between subscribers is achieved using devoted system exchange channel. Exchange consists of well-formed messages, which include connection establishing stage, address positions, information about connection rate and information about channel condition. EFFECT: increased functional capabilities due to establishing connection paths using digital and analog channels between exchange systems and subscriber lines and connection of subscriber equipment with possibility of data exchange. 6 dwg

Description

 The invention relates to communication technology and can be used as an automatic telephone exchange with connecting both digital and analog communication channels and heterogeneous subscriber lines, as well as in communication systems with a high channel availability factor.

 There are well-known telephone exchanges of domestic production such as "Quantum", "Kalinka", "Kontur" and others. See the advertising brochure of the EATS "Kalinka 32/192" JSC "Concern BETS" - Electronic ATS "Quantum", Advertising brochure MPO VT. Electronic automatic telephone exchange "Kontur-8 / 128-24", Promotional brochure JSC "TELROS"), in which there are no functions for the exchange of signal messages from subscriber to subscriber in order to change operating modes and organize the path depending on the degree of network load and remoteness of the subscriber equipment from the station.

 Known digital switching system, providing the organization of connections and information exchange between telephone subscribers using digital subscriber lines and communication channels by ed. St. SU.

 The digital switching system contains many telephones connected to the subscriber module, which, organizing a high-speed subscriber line due to temporary compaction, provides access to the subscriber concentrator.

 In FIG. 1. The structural diagram of a digital switching system according to ed. St. SU H 04 M 3/00, taken by the authors as a prototype. The system comprises a transit switching module 1, a subscriber concentrator 2, m remote subscriber modules 3, mn telephone sets 4.

 The transit switching module 1 comprises a group switching stage 5, terminal station sets 6, a linear signaling unit 7, a common signaling channel unit 8, a marker 9, and a control bus 10.

 The subscriber concentration module comprises a subscriber stage switching unit 11, an interaction signal generator 12, a common signaling channel block 13, a terminal station set 14, a control signal exchange bus 15, a call processing unit 16, a subscriber activity determination unit 17, a subscriber signaling receiver 18, a block connecting interaction signals 19, remote power supply 20.

 Each telephone set 4 contains a lever switch 21, an electro-acoustic signal transducer 22, a telephone 23, a microphone 24, a keyboard 25, a voltage regulator 26, an electronic key 27, an analog-to-digital converter 28, a digital-to-analog converter 29, a scrambler 30, a descrambler 31, a test decoder signals 32, the dialer 33, the integrator 34, the block of ringing signals 35, the one-shot 36, the multiplexer 37, the matching unit 38, the element And 39.

 The system operates as follows.

 The unoccupied state of the subscriber corresponds to the absence of logical units in the subscriber lines. In this state, the channel is not connected to the connecting line of the subscriber switching stage 11, which is fixed in the random access memory (RAM) of the call processing unit. After the subscriber picks up the handset, the lever switch 21 allows the background combination to pass through the multiplexer 37 to the output of the telephone set 4 - the background combination is transmitted to the subscriber concentrator 2, where the subscriber activity determination unit 17, scanning group streams received by the station end set 14, captures a change in the signal from the telephone apparatus 4 and reports this via bus 15 to the call processing unit 16 with an indication of the channel number defining the number of telephone apparatus 4.

 Block 16, which, in accordance with the program recorded in the permanent memory (ROM), determines what sequence of operations it should perform in this situation, determines the number of the free trunk line from the information in the RAM, and instructs the subscriber switching stage 11 to turn off the subscriber that has become active channel. After receiving a message from the receiver 18 about the appearance of logical units in this connecting line, the call processing unit 16 instructs the interaction signal connection unit 19 to turn off the Ready signal from the group flow of the interaction signal generator 12 to the return channel of the connecting line. This signal enters the telephone set 4. Having received this signal, the integrator 34 through the And 39 element includes an electronic switch 27, through which a voltage is supplied to the converters 28 and 29, and the Ready signal is heard by the telephone 23.

 When you press the button on the keyboard 25 corresponding to the number of the called subscriber, the dialer 33 generates a digital combination, which through module 2 is fed to the output of the subscriber switching stage 11. Having fixed the first digit of the dialed number, the call processing unit 16 writes it into the operational memory and gives command block 19 to turn off the signal "Ready". Similarly, the remaining digits of the number dialed by the subscriber fall into the call processing unit 16. The call processing unit 16, having determined the end of the dialing by the number of received digits, analyzes this number and, through block 13, transfers it to the marker 9 of the transit switching module 1.

 The marker 9 according to the information in the permanent memory determines which automatic station the called subscriber is connected to, finds the free connecting line in the path connected to this automatic telephone exchange according to the operational memory and gives the command of the group switching stage 5 to connect the channel of the called subscriber to this line.

 After that, all information about the established connection is transmitted to the PBX through the corresponding signaling channel (block 8 and 7).

 Subsequently, the calling subscriber receives acoustic signals (Call Control, Busy, etc.) and voice signals from the PBX of the called subscriber. When the handset is lowered, the absence of logical units in the channel from the calling subscriber is detected by the subscriber signaling receiver 18. Upon receipt of a message about this, the call processing unit instructs block 19 to issue a Busy command to the called subscriber. the called subscriber through the corresponding signaling channel. Disconnection of subscriber channels and interaction signals from the connecting lines, the call processing unit 16 and the marker 9 produce After receiving reports of rebound of the calling and called subscribers.

 With incoming communication, marker 9, having received information about the connection being established from another exchange, transmits it to the call processing unit 16 and gives the command of the group switching stage 5 to connect the line through which the call arrives with the free connecting line of module 2. Block 16 gives the command to the subscriber switching stage 11 to connect the channel of the called subscriber and the command to the unit for connecting interaction signals 19 to submit a test signal to this channel. If the called subscriber is busy, towards the module 1 and further to the calling subscriber a busy signal is transmitted.

 The test signal, falling into the called telephone 4, is received by the differentiator 32, by the signal of which the dialer 33 transmits a response combination. Having received the response combination, the subscriber signal receiver 18 and the call processing unit 16 make a conclusion about the serviceability of the subscriber line and instruct the block 19 to transmit a tone signal to the telephone set 4, and a call transfer control signal to the module side. The tone signal in the telephone set 4 is fixed by the integrator 34, which, when the switch 21 is turned on, allows it to pass through the ring signal block 35 to the electro-acoustic transducer 22. Raising the handset leads to the appearance of logical units or a signal from the analog-to-digital converter 28 in the subscriber channel, which is fixed by the receiver 18 and is perceived by the call processing unit 16 as a response to the call signal, while the command to remove the tone call is sent to the block 19.

 The presence in the well-known system of high-speed digital channels allows, firstly, to organize temporary consolidation of subscriber lines and thereby provide a large number of subscribers to the subscriber module and hub, and secondly, to organize a common signaling channel (ACS) in the area: subscriber concentrator - backhaul module. The presence in the known system of a common signaling channel allows you to quickly (without delay) organize a connection, inform the subscriber about a connection failure, change the exchange mode without destroying the connection, etc.

 A disadvantage of the known system is the lack of functionality of the system in organizing the connection in the presence of heterogeneous subscriber lines and communication channels between telephone exchanges.

 Connecting both analog and digital channels to the telephone exchange is the most likely situation today.

 On the one hand, in the process of developing the EACC, an increasing number of main digital channels (BCC) will be provided for use by the consumer. Channels will be used in compression mode for data transmission (PD) and voice paths. The information rate is 64, 32, 16 kbit / s.

 Along with digital ones, PM channels (analog channels) will remain for a long time as the most common means of channel formation. Such channels, together with connected linear equipment (signal conversion device), provide information transfer at a speed of 9600 bps at inter-station sections (between two telephone exchanges), and up to 2400, 1200 bps at channels of degraded quality.

 A similar situation may arise when organizing subscriber lines. Not always, as shown in the prototype, it becomes advantageous to have a compacted high-speed digital subscriber line between the subscriber module 3 and the subscriber concentrator 2, especially when the length of the subscriber line is a variable. In some cases, due to the great remoteness of the subscriber station, which includes one telephone and one two-wire telephone line, it is impractical to work through the subscriber module 3 (load concentrator). In this regard, the known system is suitable for one situation when the nth number of subscribers is rigidly “tied” to the subscriber module, and the length of the subscriber line does not exceed the value at which stable communication is ensured. It follows that the type of subscriber line is determined not only by the degree of intensity of the information flow, but also by the remoteness of subscribers from the telephone exchange. It is known that the higher the speed in the line, the more the distance from the subscriber to the station is reduced.

 So, at a speed in the subscriber line of 1200 bit / s, information exchange is possible at a distance of up to 20 km, at 2400 - 10 km, 16 kbit / s - 3-5 km, 32 kbit / s - less than 3 km.

 In the known system due to the presence of high-speed compressed digital information flow between the subscriber module 3 and the subscriber concentrator 2 there is no possibility in this section to change the length of the subscriber line. This is especially true for mobile subscribers.

 An attempt to reduce the speed at the inter-station section due to the lack of a bcc in the required direction or to reduce the speed in the subscriber line at the subscriber module-subscriber concentrator section due to the remoteness of telephones will lead to a sharp decrease in speech quality. The reason is the inability of the digital-to-analog and analog-to-digital converters 29 and 28 to process information at channel speeds characteristic of PM channels (2.4; 4.8; 9.6; kbit / s).

In FIG. 2 shows expert assessments of the spoken paths for various types of speech-converting devices (RPU) of vocoder type and speech conversion devices with direct coding (codecs):
channel vocoder (KB);
linear predictive coding vocoder (LPC) or lipreder;
half-coders;
adaptive delta modulation (ADM) codec;
codec and pulse code modulation (PCM);
Adaptive Differential Pulse Code Modulation (ADPCM) codec.

 As can be seen from FIG. 2, the stable operation of all types of analog-to-digital converters with direct encoding of the prototype used in the device is possible in the speed range 16-64 kbit / s. Any decrease in speed in a subscriber line or in an inter-office section below 16 kbit / s will practically lead to non-acceptance of telephone information.

 The technical task is to expand the functionality of the system by organizing paths using both digital and analog inter-station channels and subscriber lines and connecting subscriber equipment providing data exchange mode.

 The essence of the invention lies in the fact that a digital switching system is proposed, consisting of subscriber equipment, automatic telephone exchange (PBX), means of sealing the subscriber line and various types of inter-office communication channels.

 Subscriber equipment provides an interdependent exchange of data and telephone information through means of sealing subscriber line.

 In addition to the switchboard, the telephone exchange includes means for storing generation data and routes for delivering information to each subscriber, means for storing information on the degree of occupancy of switching equipment, signal generators and analyzers for organizing connections / disconnections, a channel search system (delivery route) with characteristics, providing the best voice quality that can be provided by channel equipment and subscriber lines.

 Thus, the technical results are that the best speech quality is achieved by installing the module of the speech-transforming unit (lipredor) and selecting the maximum possible speed. The speed value is entered by the operator into the storage means of the station's generation data during the network deployment period. At the time of establishing a connection between two subscribers, the speed value is adjusted according to the results of sounding by signal messages of all sections of the path. The maximum possible speed value is selected, which can be set in the path of the organized connection. Signal information is exchanged with finished messages containing the type of message, address positions, information about the establishment of speed and the situation on the channel and in the path.

 In FIG. 1 shows a structural diagram of a prototype; in FIG. 2 - characteristics of speech-transforming blocks; in FIG. 3 shows the proposed switching system; in FIG. 4 - marker 10; in FIG. 5 - speech-transforming unit 25; in FIG. 6 - multiplexers 14 and 37.

 The digital switching system contains (Fig. 3) a subscriber module 1, individual station blocks 2, a switching block 3, a linear signaling unit 4, subscriber lines 5, digital channels 6, PM channels 7, common signaling channels 8, control bus 9, a marker 10, a channel state storage unit 11, a delivery route memory unit 12, an input / output unit 13.

 The subscriber module 1 includes a subscriber multiplexer 14, a lever switch 15, a signal shaper 16, a keypad 17, a dialer 18, an electro-acoustic transducer 19, a ringing unit 20, a telephone 21, a microphone 22, a descrambler 23, a scrambler 24, a speech-converting unit 25, PC 26, controller 27, interface unit 28, first signal conversion unit 29, filter unit 30, telephone signal converter 31, telephone signal analyzer 32.

 The structure of the controller 27 includes a shaper of signal messages for transmitting data 33, an analyzer of signal messages for receiving data 34, a unit for interfacing with a telephone channel 35.

 The structure of the individual station unit 2 includes a second signal conversion unit 36, a station multiplexer 37, a signal message analyzer 38, an interaction signal generator 39, a number store 40, a source data storage unit 41, a signal message generator 42.

 The composition of the drive number 40 includes a memory unit 43 counter 44, register 45.

 The composition of marker 10 includes (Fig. 4) an identifier selector 46, an input information selector 47, a buffer memory node 48, an OR element 49, an answer analyzer 50, an address register 51, a polling unit 52, an initial data register 53, an address matrix 54, a block comparison 55, the unit for the formation of switching commands and signal messages 56, counter 57, decoder 58, the Start button 59.

 The composition of the memory block of the delivery routes 12 includes a selector routing tables 60, a memory block routing tables 61.

 The structure of the speech-transforming unit 25 includes (Fig. 5) an analog-to-digital converter 62, a calculator 63, a weighing filter 64, an error minimizing unit 65, an excitation pulse generator 66, a synthesizer 67, a digital-to-analog converter 68, a calculator 69, a parameter analyzer 70, a reference block frequency 71, the analyzer values of speed 72.

 The composition of the calculator 63 includes a block for weighing the speech signal 73, a block for weighing the pulse sequence 74, a calculator for the cross-correlation function 75, a calculator for the autocorrelation function 76, and a pulse search unit 77.

 The subscriber multiplexer 14 and the station multiplexer 38 (FIG. 6) include a transmission unit 78 and a reception unit 79.

 The transmission unit 78 includes a distributor 80, input drives 81, 82, 83, a signal driver 84, OR elements 85, 86.

 The reception unit includes a clock analyzer 87, a distributor 88, keys 89, 90, 91, channel drives 92, 93, 94, a speed analysis unit 95.

 An I / O block 13 is connected to the marker of the telephone exchange 10 via the bus. By means of the inputs / outputs, the marker 10 is connected to the memory block of the delivery routes 12, the other inputs and outputs of which provide the connection of the channel state storage unit 11. The marker 10 is connected via the signal control bus 9 with a switching unit 3, a linear signaling unit 4, and with elements and nodes of individual station blocks 2: a source data storage unit 41, a number accumulator 40 and a signal message generator 42. Each individual station block ok 2 through the subscriber line 5 is connected to the subscriber module 1, which contains the keyboard 17 connected in series, the dialer 18, the interface unit 28. The output of the lever switch 15 of the subscriber module 1 is connected to the control input of the ringing unit 20, the output of which is connected to the electro-acoustic transducer 19. Input interaction signal generator 16 is connected to the output of the lever switch 15. The second output of the ringing signal block 20 through the telephone signal analyzer 32, the telephone signal converter 31 and the filter unit 30 is connected to the telephone 21, and the third output is to the second input of the interaction signal generator 16, the output of which through the interface unit 28 is connected to the signal input of the subscriber multiplexer 14, the output of which through the signal conversion unit 29 is connected to the subscriber line 5.

 The information inputs and outputs of the subscriber multiplexer 14, respectively, through the scrambler 24 and descrambler 23 are connected to the information inputs and outputs of the speech-converting unit 25, the second input of which is connected to the microphone 22, the second output through the filter unit 30 to the telephone 21. The control input of the speech-converting unit 25 is combined with the output of the telephone signal analyzer 32 and the input of the converter 31, the second signal and information inputs and outputs of the subscriber multiplexer 14 are connected via a controller 27 to a personal computer 26, and the output of the multiplexer 14 is connected to the input of the ringing unit 20.

 Each individual station block 2 contains a series-connected signal analyzer 38 and an interaction signal generator 39. The signal input of the multiplexer 37 is connected to the signal output of the switching unit 3, the information inputs and outputs of which are connected to the information inputs and outputs of the multiplexer 37, the signal output of which is connected to the input signal analyzer 38, the second output of which is connected to the input of the source data storage unit 41, the third output is to the input of the number 40 storage device, the first whose output is connected to a second input of the signal generator 39 interaction, and the second output - to a third input of the signal generator interaction 39 whose output is coupled to another signal input of MUX 37. The output signal generator 42 connected to the communications signal input switching unit 3.

 The system operates as follows.

 Before starting operation, the source data storage unit 41 and the memory block of the delivery routes 12 are loaded with the information necessary to support the process of normal and reliable operation of the system. Download is carried out by the telephone exchange operator from the input-output unit 13. As the input-output unit 13, a personal computer of any type can be used. The message with the initial data is entered into the marker 10, which distributes the information into blocks 12 and 41 of each individual station block 2. The storage unit 41 records the stage of establishing the connection (establishment, disconnection, information, connection, confirmation of establishment, confirmation of disconnection - only during the organization connection from the subscriber module 1), the outgoing address (s) and the speed value of the connected subscriber equipment 1. In the memory block 12 is written route-address table, reflecting the option You bring information to each subscriber having an exit through this station. Alternatively, the route table has a structure (see table 1).

 In the column "Delivery channel" indicates the number of the channel through which it is necessary to transmit a message to an adjacent (neighboring) station. If the subscriber is local (not belonging to this station, then the subscriber line number and subscriber number of the recipient are indicated.

 Information is recorded from marker 10 to block 41 via the control bus 9. Exchange is carried out by finished messages. Each input message has an address part (block address) and an information part (see table 2).

 The address positions correspond to the block to which the message entered by the operator is intended.

 After downloading the initial data, the subscriber (telephone network user) can start working.

 The organization of the connection is supported by the interface unit 28, where the orderly transmission of signal messages from the shaper 16 or the dialer 18 is carried out. The subscriber multiplexer 14 provides a temporary seal of information flows coming from the telephone equipment of the telephone 21 and the microphone 22 with a personal computer, as well as temporary compaction of service (signal) information, and depending on the type of subscriber line provided (digital, analog), various options are possible you are seals. If the means of generating digital channels (joint C1-I, GOST 27232-87) with speeds of 16, 32, 48 kbit / s, etc., are used as signal conversion blocks 29 and 36, i.e. the speech-transforming unit 25 can operate at the maximum possible (for the PM channel) frequency, and the data source at the speeds of 1.2 generally accepted for this type of communication; 2.4 kbps In this case, the temporary distribution of the types of information in the subscriber line, using the multiplexer 14 will look, as illustrated in table. 3.

 With this distribution, the total speed in the subscriber line 5 approaches the standard value and is 16 kbit / s.

 If modems (digital channel to analog signal converters) are used as signal conversion blocks 29 and 36, the maximum speed of which is at best 9.6 kbit / s, then the speech-converting block 25 can operate at a speed of 4.8 kbit / s, data transmitted at a speed of 1.2 kbit / s. The temporary distribution of the types of information in the subscriber line 5, including the service one, will look as illustrated in Table. 4.

 With this distribution of speeds, the subscriber line 5 can be analogous if the signal conversion blocks 29 and 36 are made in the form of modems that convert digital signals to analog, followed by their transmission on the subscriber line 5.

 As an example of the organization of the subscriber line 5 in this material presents a variant of the organization in accordance with Fig.

 If necessary, organize a telephone conversation, the subscriber picks up the telephone. The signal from the output of the lever switch 15, the shaper 16 will generate a signal message that through the interface device 28 and the multiplexer 14, the signal conversion blocks 29, 36, the multiplexer 37 through the signaling channel (D-channel) will go to the signal analyzer 38, 18. All signal messages circulating on the D-channel in the areas of the organized connection (subscriber lines, inter-office channels) have the structure of the finished message, the format of which is presented in Table. 5.

 All signal messages transmitted from the subscriber module 1 are transmitted along the path: the interface unit 28, the multiplexer 14, the conversion units 20, 36, the multiplexer 37, the analyzer 38, the source data storage unit 41, or the number store 40.

 All signal messages transmitted from the individual station unit 2 are transmitted to the subscriber module 1 along the path: linear signaling unit 4, switching unit 3, multiplexer 37, signal conversion units 36, 29, multiplexer 14, ringing unit 20 or analyzer 34, or an interaction signal generator 39, a multiplexer 37, signal conversion units 36, 29, a multiplexer 14, a ring signal block 20, or an analyzer 34.

 At the positions of the "flag" is placed a code sequence (several bits), indicating the beginning and end of the message. The position "outgoing address" includes the address of the terminal, which is part of the subscriber module 1.

 At the "Message Type" positions, identifiers are placed that indicate the stages of establishing a connection and the state of the path: establishment, confirmation of establishment, information, disconnection. At the "Information" positions are located: the required exchange rate, reasons for disconnection, buzzer signals involved in organizing the connection (disconnection), numbers of the called subscriber's number, station readiness for incoming call service. The analyzer 38 perceives the received message as a signal "handset (MTT) off." In response, after the analyzer 38 is exposed to the interaction signal generator 39, the latter will generate a “Ready” signal. As part of the signaling message, the Ready signal through multiplexers 36, 14 and signal conversion blocks 29 and 36 is transmitted to the ringing unit 20. The ringing unit 20 will receive the Buzzer buzzer, which is detected by the analyzer 32 and through the filter unit 30 and the converter 31 will go to telephone 21. With the signal “Ready”, the subscriber on the keypad 17 dials the first digit of the number of the called subscriber. The dialer 18 generates a digital combination, which is transmitted to the individual station unit 2 along the same path as the previous signaling message. The first digit of the number in the signal message is detected by the analyzer 38 and recorded in the drive 40. Having received the first digit of the number, the drive 40 will transmit the signal to the generator 39. With the acceptance of this signal, the ringing signal block 20 will stop the “Ready” signal to the telephone 21. The subsequent digits of the number the called subscriber is sequentially entered into the drive 40. Each receipt of a digit is fixed by the counter 44. Upon completion of a set of a certain number for this system of digits, the counter 44 will work, the output signal from which it will start the interaction signal generator 39. The generator 39 will generate a signal message corresponding to FIG. 10. The position "Message type" takes the value "Installed", the position "Information" - "Wait." The signal "Wait" is brought to the phone 21.

 Simultaneously with the operation of the counter 44, the telephone number is transferred from the drive 43 to the register 45. The information recorded in the register 45 is periodically requested by the marker 10.

 Marker 10 operates in the polling mode of individual station blocks 2 (HMB). The survey is conducted by sequentially generating a packet in each HMB with a request for information available in drive 40 (register 45). If there is such information, the number of the called subscriber is entered into the marker 10 as a response to the request. With the receipt of the number, the marker 10 by the next request to the source data storage unit 41 will receive information about the stage of establishing the connection, the value of the speed with which the subscriber is ready to work, for the organized connection and the address of the calling subscriber. Having received the initial data, the marker 10 turns to the memory block of the delivery routes 12, where each requested telephone number corresponds to a channel number (channel numbers), through which a ringing signal and speed value can be delivered to the subscriber. The speed value contained in the signal message received by marker 10 is adjusted downward if the selected route (channel number) cannot provide the requested value.

 Selected from the table. 1, the delivery route is fixed in the storage unit 11 as busy until the end time is received from the subscriber module 1. After selecting the channel, the marker 10 issues a command through the bus 9 and the control input of the switching unit 3 to connect the driver 42 to the ACS channel, and to the input of the driver 42 marker 10 gives an alarm message containing the incoming and outgoing addresses, the speed with which the station can organize the path from the subscriber to the adjacent station, the stage of organizing the connection, ("establishment"). At the “Information” position (Table 2), the code sequence will correspond to the “Call” signal. Framed with flags (table. 2), the signal message from the shaper 42 through the switching unit 3 via the ACS channel will arrive at an adjacent station. At the adjacent station, the signal message is incoming, it is fixed by the linear signaling unit 4. Marker 10, in addition to the station blocks 2, constantly polls the linear signaling unit 4. At the next request, if there is a signal message in the unit 4 from the communication channel, it is rewritten to marker 10, where address positions are analyzed and the telephone number of the called subscriber is compared with the delivery routes to this subscriber using the procedure described above.

 The information channel (B-channel) selected by marker 10 is marked in the storage unit 11 as busy, and a signal message is transmitted from the shaper 42 through the switching unit 3 via the ACS channel 8 to the adjacent station. Switching the alarm channel in the switching unit 3 is carried out by command from the marker 10 via bus 9.

 If, as a result of the analysis, the address of the called subscriber belongs to this station, i.e. the subscriber is connected to this station, marker 10 connects the line signaling unit 4 through the switching unit 3, the multiplexer 37 and the signal converter 36 to the subscriber line 5. At the same time, the marker 10 sends a command message “Call confirmation” to the caller to transmit to the caller. The signal message received from the shaper 4 through the switching unit 3- multiplexers 37 and 14 by the block 20 is perceived as a “Call” signal, from which the electro-acoustic transducer 19 is triggered. After the MTT subscriber picks up the “Call” to the electro-acoustic transducer 19 stops. At the same time that the MTT is raised by the signal from block 20, the driver 16 will generate a “Call confirmation end” signal to the caller’s address, which also contains information about the selected speed. Shaper 16 is constructed in such a way that when the MTT is raised and the “Call” signal is present in block 20, the shaper 16 will transmit the signal message “End of call confirmation” to the station block 2 through the interface unit 28. At the same time, the value of speed in the signal message received from the calling subscriber is detected by the analyzer 72 (Fig. 5), which, acting on the reference frequency block 71 of the speech-converting block 25, will provide the required, from the station, high-speed mode of telephone information exchange. With the receipt in the analyzer 37 of the signal message "End call confirmation" it is rewritten in the storage unit of the source data 40.

 At the next polling cycle, marker 10, having detected the “End of call confirmation” signal in storage unit 41, and with it information about the destination address and transmission speed of the terminal equipment (subscriber module), in accordance with the delivery routes stored for each subscriber in the block the memory of the delivery routes 12, will form a command for switching unit 3, by which the information path for the requested subscriber is switched off (B-channel) along the following circuit: multiplexer 37, switching unit 3, BCC 6 or PM channel 7. Signal message with information about the end of the call confirmations and the value of the speed with which the called speech-converting unit 25 of the called subscriber will work, it will be generated by a command from marker 10 and transmitted via switching unit 3 through the switching block 3 to the adjacent station via ACS channel 8. If the adjacent station is in transit, then marker 10, upon detection of “End of call confirmation”, by analogy with the previous station, in accordance with the information stored in the memory block of the delivery routes 12, generates a command to shut down the information path in switching block 3. Simultaneously through the D-channel with the help of the shaper 42 the signal message "End of call confirmation" will be transmitted to the caller. At the calling station, marker 10, having detected "its" subscriber, will connect information channels 6 or 7 and the signaling channel 8 to the multiplexer 37. Having received the signal "End of call confirmation", the block of ringing signals 20 of the eliminating station stops generating "Call confirmation" signals to the telephone 21, the analyzer 72 (Fig-5) detects the selected speed value and rebuilds the block of reference frequencies 71 at the desired speed. With the completion of the formation of the call, a telephone exchange session begins with the microphone 22. The analog signal is converted in the speech-transforming unit 25 into digital form in accordance with the algorithm adopted for lipreaders.

 If at the time of the next call coming from the communication channel it turns out that the called subscriber is busy (busy information is stored in the source data storage unit 41) as a connection establishment step, marker 10 returns the incoming request to the calling subscriber using shaper 42 as a busy signal.

 The signal "End" (MTT set) is generated by the signal from the lever switch 15. According to the signal from the switch 15, the driver 16 through the interface unit 28 and the multiplexer 14 will transmit a signal message with the sign "End" on the subscriber line 5. The “End call” signal is processed using the same nodes and blocks as the rest of the signal messages, i.e. first it is detected by the analyzer 38, and then it is copied to block 41. The storage unit 41, having fixed “Hang up” via bus 9, will rewrite it into marker 10. According to the received information, marker 10 will remove the sign of busyness for the previously established path by accessing storage block 11, and will start driver 42 to transmit the “End” (“Busy”) signal to an adjacent station. After the signaling message is transmitted, the established connections are destroyed, i.e. channel resources are freed for use in the following connections. The signal "End" through the inter-office connection or communication channels enters the transit station and through the switching unit 3 is broadcast in the direction of the calling (called) subscriber. Simultaneously with the receipt of the signal "End" with the help of the marker 10 is the release of channel resources.

 In more detail, the operation of the marker 10 and the speech-transforming unit 25 is shown in FIGS. 4 and 5.

 The initiator of the interaction of all nodes and blocks of the system is the marker 10. The interaction of the marker 10 with the block 41, the shaper 42, the number accumulator 40 and the linear signaling unit 4 is carried out via bus 9 by forming and exchanging commands and receiving a response according to a previously prepared program. The request-response interaction time is calculated in such a way that if the requested device is ready to serve this request, token 10 does not require any suspension in its work, and it will continue its actions to execute the command, waiting for the timely response to the request for the requested information . The initial data for loading is entered by the operator of block 13 in the form of a message, the format of which corresponds to (table 2). On official grounds (address), the identifier selector 46 (Fig. 4) detects this type of message, which means that the source data is loaded into the block 41 of the individual station block 2. The output signal from the selector 46 automatically generates and reads from the register 51 the address of the storage unit 41. The selector 47 provides input to the node of the buffer memory 48 of the information part of the message. After the address part is transmitted, the signals from the selector 46 will calculate the initial data (the address of the connected subscriber and the minimum value of the speed at which he intentionally conduct information exchange) to the source data storage unit 40.

 Route-address tables are formed by the operator of the input-output block 13 in accordance with table. 1.

 Entering route-address tables is provided through the inputs and outputs between the marker 10 and the memory block of the delivery routes 12 (two outputs from the marker 10 to the memory block 12 and one input from the block 12 to the marker 10).

 At the "block address" positions, the operator dials an identifier corresponding to the address information. The selector 60 detects this type of message and generates a write signal to the memory unit 61. The write form of the address tables corresponds to the table. 1. After the initial data is loaded with the “Start” button 59, the operator starts the polling unit 52. From this moment, the process of operating the system begins. According to the signal from the polling unit 52, the selector 46, acting on the register 51, will ensure the transmission of requests to the addresses of the individual station blocks 2. The address register 51 implements the sequential polling procedure with each individual station block 2 (drive - 40, storage unit for initial data 41) and the block linear alarm 4. If there is a telephone number in drive 40, an answer will be generated containing the telephone number of the called subscriber, which will be detected by analyzer 50 and rewritten into the source data register 53. After polling the source data storage unit 41, information containing the step of establishing a connection, speed value, and the address of the calling subscriber is recorded in register 53. After the initial data are accumulated by the signal from the register 53, the address matrix 54 is started and the interrogation and reading cycle begins in the comparison unit 55 of the telephone numbers and speed values stored in the memory unit 61.

 After finding the desired channel number in accordance with Table 1, the comparison unit 55 will give a read signal to the register 53. If the selected channel has a lower speed value than the caller requires, the comparison unit 55 corrects this parameter, providing a new input into the input data register 53 speed value. According to the source data stored in register 53, block 56 will generate a command to turn off the signaling channel in switching unit 3. The command to turn off from the output of block 56 is sent to selectors 46, 47. The selector 46 recognizes the command and transfers it to the block using register 51 switching 3, and the address of switching unit 3 is formed in the register 51, and the command code for switching off the signaling channel through the selector 47 is recorded in the buffer storage 48 and after the address part enters the switching unit 3. The value of the selected channel for I information path, recorded in block 55, is stored until the signals "Busy", "Hang up". At the same time, the channel busy signal from block 55 enters the address matrix 54, which marks the selected information channel in the memory block 11 as busy. After the signal path is turned off, the signal message containing the address of the calling and called subscribers, speed value, information about the stages of establishment is connected, formed by the block 56, through the selectors 46, 47 will go to the shaper 42.

 When forming request markers 10 to the address of the linear signaling unit 4 and receiving information about a call from a subscriber connected to this station to a sent request, register 53 initializes the program to search for the desired subscriber from the table of addresses stored in blocks 11 and 12. If, during the comparison, block 55 that the connection to the called subscriber is impossible due to the busy channel (subscriber line), the counter 57 will work. The counter 57 generates an output signal when the matrix 54 completes the polling cycle of all rows of the address table in bl oce 61. If, as a result of a complete survey, the comparison unit 55 does not fix a free channel, the decoder 58 will generate a signal that ensures the formation of a busy signal for the caller.

 The speech-transforming unit 25 is shown in FIG. 5 as a synthesizer and analyzer of a speech signal based on the linear prediction method. From the known varieties of methods and linear prediction blocks for the proposed digital switching system, a method and a device with multi-pulse excitation (MIM) have been selected. Due to the fact that the method with multipulse excitation and implementation have been known since 1966 and are widely covered in the literature, this material gives a general principle for implementing the well-known method of speech conversion. In particular, this device is described and set forth in the form of a technical solution in the literature: G. Korotaev Analysis and synthesis of a speech signal by linear prediction. Foreign electronics 1990 t, N 3.

 The method with MIV is based on the method with excitation from pulses of the fundamental tone (OT), the so-called LPC method. The LPC excitation signal is transmitted through the channel in the form of three parameters: the period of the fundamental tone for voiced sounds, the tone-to-noise signal that characterizes at the moment either tone or noise and signal amplitude. Unlike the LPC method, the multi-pulse excitation method determines the excitation for any speech segment. In this model, instead of one impulse per period of the fundamental tone, excitation from several impulses is created for voiced speech, their location (m) and amplitude (g) are determined. The amplitude and location of the pulses are determined using the procedure "analysis through synthesis".

Upon receipt of the excitation signal from the generator 66 to the input of the synthesizer 67, speech samples S _n are created, which are then compared in the calculator 63 with the corresponding speech samples of the original speech signal S _n received at the input of the weighting unit of the speech signal 73.

 A sample of the speech signal is predicted by a linear combination of previous reports in accordance with expression (1).

где

предсказанное значение речевого сигнала;
a_i - весовой коэффициент;
M - число коэффициентов линейного предсказания (порядок предсказания).

Where

the predicted value of the speech signal;
a _i is the weight coefficient;
M is the number of linear prediction coefficients (prediction order).

значениями выборки речевого сигнала определяет ошибку предсказания e_n(остаток предсказания)

Процедура речепреобразующего блока 25 минимизирует ошибку между исходными s_n и восстановленным

сигналами в соответствии с приемлемым критерием, используемым в исследованиях речи - критерием среднеквадратичной ошибки. Критерий обеспечивает минимизацию значения ошибки e_n. Минимизация e_n находится путем дифференцирования уравнения (2).The difference between true S _n and predicted

the sample values of the speech signal determines the prediction error e _n (the remainder of the prediction)

The process of the speech-transforming unit 25 minimizes the error between the original s _n and the restored

signals in accordance with an acceptable criterion used in speech studies - the standard error criterion. The criterion minimizes the value of the error e _n . Minimization of e _n is found by differentiating equation (2).

и приравнивания производной к 0. Функции минимизации e_n реализованы в вычислителях кросскорреляционной и автокорреляционной функциями 75, 76. Определение местоположения импульса находится тогда, когда нормализованное значение кросскорреляционной функции R, становится максимальным и реализуется в блоке поиска импульсов 77.

and equating the derivative to 0. The minimization functions e _{n are} implemented in the computers of the cross-correlation and autocorrelation functions 75, 76. The location of the pulse is found when the normalized value of the cross-correlation function R becomes maximum and is implemented in the pulse search block 77.

,
где N - число отчетов;
S_w(n) - взвешенный речевой сигнал;
h_w - взвешенная импульсная характеристика синтезирующего фильтра;
g - местоположение импульса;
m - амплитуда импульса.The optimal location and amplitude of the pulses are based on the differentiation of the power equation of the prediction residual E between the original and synthesized speech

,
where N is the number of reports;
S _w (n) is a weighted speech signal;
h _w - weighted impulse response of the synthesizing filter;
g is the location of the pulse;
m is the amplitude of the pulse.

 The root-mean-square error criterion does not take into account auditory perception, i.e. masking by a signal of a large level of a signal of a small level, for example, quantization noise. Therefore, the quantization noise is distributed so that most of it is located at the locations of the formant regions of the speech signal, and the smaller - between the formant regions. This requirement is met by the weighting filter 64. The weighting filter 64 suppresses the noise between the formant regions in the spectrum of the speech signal and does not suppress the formant region where it is masked by the speech signal. As a result, the interfering effect of noise in synthesized speech is reduced.

 Information about the positions m and amplitudes g of the excitation pulses is sent to the reception along with the LPC parameters. The indicated parameters are detected by the parameter analyzer 70 at the reception, by which the cross-correlation and autocorrelation functions, and therefore the speech signal, are restored.

 When using the TID method at a speed of 9.6 kbit / s, the synthesized speech corresponds in quality to PCM signals (with the logarithmic law of compression) with a transmission speed of 52 kbit / s (according to the literature, Korotaev "Analysis and synthesis of a speech signal ..." )

 The introduction of the speech-transforming unit 25 - lipreder into the telephone communication path not only provides access to digital switching facilities (switching unit 3), but also does not impair the quality of speech when transmitting information over low-speed channels. According to the results of studies carried out at the Institute, when using the Δ-code as a converter at a speed of 16 kbit / s, syllabic intelligibility is 85%, at a speed of 32 kbit / s - 90%. Data on syllabic intelligibility at a speed of 64 kbit / s are not available at the institute. When using a lipreader as a speech transformer, syllabic intelligibility at a speed of 9600 bps (PM channels) is 92%, at a speed of 4800 bps - 87%, and at a speed of 2400 bps - 85%. In accordance with GOST B20775-75 (Table 3), finding syllabic intelligibility at the level of 90% and higher allows us to classify the telephone system in the highest class. Thus, when switching the proposed system from digital channels to analogue PM channels with operating speeds of 9600 bps, the speech quality does not deteriorate (it remains in the same class). The construction of a system that ensures operation, depending on the situation in the network, both via digital and PM channels, allows in cases of increased load on the network to increase the reliability in organizing the connection. Reliability is expressed in the fact that if the digital channel is busy, the marker 10 will provide the connection table of bypass (backup) PM communication channels along the route table.

 Data input from the PC 26 to the switching system is carried out through the controller 27 and the multiplexer 14. The multiplexer 14 has inputs / outputs (information and signal channels, channels B and D, respectively). The procedure for establishing a connection is similar to the procedure for establishing a connection during a telephone exchange. To establish a connection with a similar subscriber using a PC keyboard, the operator imitates picking up the handset, as in the case of establishing a connection for voice communication. The signal generated in this case in the form of a code sequence enters the former 33, by which a signal message is generated. The analyzer 34 records the readiness of the station to provide channel resources and brings this availability to the operator. The operator dials the number of the called subscriber and after the organization of communication is exchanging data. Exchange is carried out through the interface unit 35 of the controller 27.

 Data transmission and voice exchange are conducted independently. The user of the personal computer 26 and the telephone subscriber have each address (telephone number). Data, speech and signaling information in the subscriber line 5 are compressed multiplexer 14.

 In the proposed embodiment, the mode of exchange of information (telephone and data) is shown under the following initial conditions. Speech is exchanged at a speed of 9.6 kbit / s, data - 2.4 kbit / s. The subscriber line 5 is sealed with a multiplexer 14 and 37 in accordance with FIG. 8. The signal conversion blocks 29 and 37 provide the conversion of discrete signals into a bio-pulse form in accordance with the joint C1-I (GOST 27232-87).

 In this mode, the subscriber module 1 (in the case of simultaneous transmission of voice and data) will require one subscriber line and two PM channels. The procedure for organizing a connection with the participation of a personal computer 26 is similar to the procedure for organizing a connection from telephone sets.

 The subscriber multiplexer 14 and the station multiplexer 37 (Fig. 6) provide compression and distribution of two information streams (B-channels) and one signal (D-channel). Each of these streams enters the input drives 81, 82, 83 of the transmission unit 78. The clock signals (flags of the end and end of the signal) and the input information are compressed by the distributor 80. At the reception, the clock is detected by the analyzer 87, the output signal from which the distributor 88 will start. The distributor 88, sequentially acting on the keys 89, 90, 91, it provides the distribution of information and signal flows along B and D channels, and drives 92, 93, 94 with a speed set after probing the channel provide information on information and signal channels.

 The proposed digital switching system provides a wide range of services to subscribers that meet modern requirements and systems with the integration of services, taking into account both combined and separate transmission of voice, data and facsimile information. Moreover, unlike the prototype device, the provision of the above services is provided when using not only digital, but also analog communication channels, as well as mixed digital-analog communication channels.

 This makes it possible to deploy the system with the provision of modern services to subscribers already at present on the existing network of analog communication channels. When introducing digital communication channels, the proposed system will ensure operation when using a combined digital-analog network. When switching only to digital channels, the proposed system ensures operability, as a result of which the proposed technical solution does not lose its relevance.

 The measure and quality of the services provided to subscribers will depend on the type and quality of the provided communication channels. When using normalized PM communication channels, the effective transmission rate, which is practically reached at present, lies in the range of 9.6-16 kbit / s. When using the bcc, the achieved speed is 64 kbit / s.

As an example, the following possible options for providing digital endings to subscribers, depending on the type of channel:
at 9.6 kbit / s - speech termination of 4.8 kbit / s;
- PD (facsimile) 2.4 kbps;
- synchronization of 1.2 kbit / s;
at 16 kbit / s - speech termination of 9.6 kbit / s;
- PD (fax) 2.4 kbps;
- synchronization of 1.2 kbit / s;
at 64 kbit / s - speech termination of 9.6 kbit / s;
- PD (fax. Communication) up to 4.8 kbit / s;
- synchronization of 1.2 kbit / s.

 The presented distribution of digital streams stems from both the possibilities mentioned above and the sufficiency of the information transfer rate of 9.6 kbit / s for transmitting voice information with a fairly high quality when using a lipreader as a speech transformer.

Claims (1)

 A digital switching system comprising a switching unit and a marker connected via a signal control bus to n individual stationary units, each of which is connected to a subscriber module via a subscriber line, the individual station block comprising a station multiplexer, signal analyzer and an interaction signal generator connected in series, the subscriber module contains a lever switch, a ringing unit, a keypad, a dialer, a subscriber multiplexer , an electro-acoustic transducer, a telephone, a microphone, a scrambler and a descrambler, wherein the keyboard, the dialer are connected in series, the output of the lever switch is connected to the control input of the ringing unit, the output of which is connected to the electro-acoustic transducer, characterized in that the input-output unit is additionally introduced via a bus connected to the marker input, the inputs and outputs of which are connected to the memory block of the delivery routes, the other inputs and outputs of which are connected to the channel state storage unit Allo, and a linear signaling unit, a second signal conversion unit, as well as a source data storage unit, a number storage device and a signal generator, each of which is connected via a signal control bus to a marker and a linear signaling unit, the output of which is through the switching unit is connected to the signal input of the station multiplexer, the information inputs / outputs of which are connected to the switching unit, and the signal output is connected to the input of the signal analyzer messages, the second output of which is connected to the input of the source data storage unit, the third output - to the input of the number storage device, the first output of which is connected to the second input of the interaction signal generator, and the second output - with the third input of the interaction signal generator, the output of which is connected to another signal the input of the station multiplexer, the output of the signal shaper is connected to the signal input of the switching unit, an interaction signal shaper is introduced into each subscriber module, a conversion unit, a controller connected via a bus to a personal computer, the input of the interaction signal generator being connected to the output of the lever switch, the second output of the ringing signal unit via series-connected telephone signal analyzer, the telephone signal converter and the filter block connected to the telephone, and the third output connected to the telephone the second input of the driver of the interaction signals, the output of which through the interface unit is connected to the signal input of the subscriber multiplexer, inputs and outputs to of which, through the first signal conversion unit, they are connected to the subscriber line, the information inputs and outputs of the subscriber multiplexer are respectively connected via the scrambler and descrambler to the information inputs and outputs of the speech conversion unit, the second input of which is connected to the microphone, the second output through the filter unit to the telephone, and the control input the speech-transforming unit is connected to the second output of the telephone signal analyzer and the input of the telephone signal converter, the second signal and information inputs ode subscriber multiplexer connected to the controller, the subscriber multiplexer signal input is connected to signal inputs of rings and the controller unit.

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