JPS59131245A - Exchange of data line - Google Patents

Abstract

PURPOSE:To attain application of a general-purpose MODEM to an envelope type synchronous data exchange for connection of terminals, by providing an envelope/non-envelope line connection converting circuit into an exchange. CONSTITUTION:The S and F bits are added to the transfer data given from a terminal 1 of a bearer MODEM21 of the terminal side to give an analysis to the envelope data transferred from the side of an exchange 4. A bearer MODEM23 transmits the envelope data of the exchange side from the MODEM21. A subscriber circuit 43 relays a subscriber line multiplexing circuit 42 and the MODEM23. Then the circuit 42 is connected to a time division exchange device 41. A terminal 1' is connected to a general-purpose MODEM24 via a general- purpose MODEM22 and a transmission line. A subscriber circuit 44 resolves the envelope data sent from the exchange 4 and transmits the data and the control signal to the MODEM24. Otherwise the circuit 44 assembles the envelope.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a data line switch, and more particularly to a data line switch that can use both a bearer modem and a general-purpose modem as a modem (modulator/demodulator) of the switch connected to a data terminal. . Note that the bearer modem is a modem that has an envelope function for assembling and disassembling data envelopes, and a non-envelope function for handling envelope data as it is.

[Description of prior art]

In recent years, there has been a trend toward digital data exchange systems, and a shift is being made to a system in which synchronous data terminals are connected to synchronous line exchanges. During this transition period, the company has decided that it is possible to use both bearer modems for synchronous data exchange and analog general-purpose modems for compatibility with conventional analog data lines as modems for synchronous line switching equipment. However, it is difficult to realize this because the transmission methods for calling signals, disconnection signals, etc. are different between general-purpose modems and bearer modems.

That is, to explain the transmission method of call origination and disconnection signals in the synchronous line switching system, FIG. 1 is a block diagram of the conventional synchronous line switching system.

In FIG. 1, 1 is a data terminal, 2 is a bearer modem on the terminal side, 3 is a bearer modem on the exchange side, and 4 is a data line switch. Envelope data in the format shown in FIG. 2 is sent and received between bearer modems 2 and 3. . This envelope data consists of 6 (or 8) data bits, 1 status bit (hereinafter referred to as S bit), and 1 bit frame bit (hereinafter referred to as F bit) that indicates the position of this S bit. is added. These 8 bits are used as call/disconnection signals, and are 0'' in the disconnected state, become 1 when the call is made, and become 0 again when the call is disconnected.Such a signal format is an 8-bit envelope (data 1 when the bit is 8 bits
o-bit envelope). Then, the terminal side bearer modem 2 adds the S bit and F pit to the data transmitted from the data terminal 1, assembles an envelope, and sends it to the transmission path, and also adds the S bit and F pit to the data transmitted from the transmission path. The bearer modem 3 on the exchange side transmits envelope data from the terminal modem 2 to the exchange 4 side, and sends the envelope data from the exchange 4 side to the terminal side. It has a function of transmitting to the side modem 2.

On the other hand, when a general-purpose analog modem is used, the transmission method for calling and disconnecting signals is to turn on and off a carrier signal for modem transfer to generate the calling and disconnecting signals.

[Purpose of the invention]

The present invention has been made in view of the above technical problems.
It is an object of the present invention to provide a data line exchange that can use both an envelope bearer modem and a general-purpose modem to accommodate data terminals.

[Key points of the invention]

The present invention relates to a data line exchange for connecting synchronous data terminals, the exchange having an interface used for connecting synchronous data terminals, and having a C0ITT-V, 24 standard general-purpose modem and an envelope. Equipped with two types of bearer modem interfaces, the interface with the general-purpose modem of the Jiang standard allows you to turn on/off the carrier wave, and the bearer modem uses the S bit 0#"1" in the envelope data for all call origination or call reception. It is characterized in that it is equipped with an interface circuit used as a signal, and that both a general-purpose modem and a bearer modem can be used for data terminal connection.

[Explanation based on examples]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 3 shows a connection configuration between the data line exchange 4 and the data terminal 1. The data terminals 1.1' are respectively connected to modems 21 and 22 located on the data terminal side.

21 is a bearer modem, which adds the S bit and F bit to the data transferred from terminal 1 and assembles an envelope)
, and also decomposes the envelope data transferred from the exchange side. 22 is a general-purpose modem, which transfers data from the terminal or data from the exchange side as is. In this case, the interface between the bearer modem 21 and the terminal 1 is CC TT-X.

21 is used, and as an interface between the general-purpose modem 22 and the terminal 1, a CC engineering TT-V 24 is used.

In general, the network control device 122 is connected to the general-purpose modem 22 since the 24 terminal does not have a call control function for switching connection. The bearer modem 21 and the general-purpose modem 22 are respectively connected to a bearer modem 23 and a general-purpose modem 24 on the exchange side via transmission lines, respectively.

The bearer modem 23 transmits envelope data from the terminal side modem 21 to the exchange side, and on the other hand, transmits envelope data from the exchange side to the terminal side.

Further, the general-purpose modem 24 is a modem having the same configuration as the general-purpose modem 21. The modems 23,24 are each connected to a subscriber circuit 43,44 in the n exchange. The subscriber circuit 43 is an envelope bearer modem connection circuit, and the subscriber circuit 44 is a general-purpose modem connection circuit.

The subscriber circuit 43 transmits the envelope data from the exchange side to the bearer modem command along with its timing clock, temporarily holds the envelope data from the bearer modem 23 in envelope units, and transmits it to the exchange side at the timing specified by the exchange 4. .

The subscriber circuit 44 decomposes the envelope data from the exchange side, and sends the data and a control signal based on S bits to the (v, . . . , 24) interface line of the general-purpose modem 24, respectively. Furthermore, a control signal on the v,24 interface of the general-purpose modem 24 is added to the non-enveloped data from the general-purpose modem 24 side, an envelope is assembled, and the data is sent to the exchange 4.

Subscriber circuits 43, 44ii: have an interface with the subscriber line multiplex circuit 42 within the exchange. The subscriber line multiplexing circuit C time-division multiplexes data signals from a plurality of subscribers and transmits them to the time-division switching device 41. Further, the subscriber line multiplexing circuit 42 decomposes (Dθmultipl−θx) the multiplexed data received from the time division switching device 41 and transmits the data to each subscriber.

FIG. 4 shows interface signal lines connecting the modem 23, 24, subscriber circuits 43, 44, and subscriber multiplex circuits, respectively, and a detailed block configuration of the subscriber circuits 43, 44. Table 1 below shows the meaning of the signals of each signal line in FIG.

In FIG. 4, the RD401 signal inputted from the subscriber line multiplexing circuit 42 to the subscriber circuit 43 is directly sent to the bearer modem via the drive circuit. This RD401 signal is already in envelope format. The RD202 signal from the bearer modem 23 is supplied to the reception buffer circuit 410 through the reception circuit. The subscriber circuit 43 has a built-in clock generating circuit 4]1 which generates clocks of various speeds using a strap, and can be connected to modems of various speeds as shown in Table 2. One output of the clock generation circuit 411 is supplied to the reception buffer 410, and the other output is outputted to the bearer modem 23 as a ROM-B 203 signal. The envelope data temporarily held in the reception buffer 410 is the RcF1403 frame signal from the exchange side.
The signal is supplied to the subscriber line multiplex circuit 42 as a BD 402 signal at the timing of the 64kHz2404 signal, which is the exchange clock. Also, 64) c) from the exchange side.
The 1z404 signal passes through the drive circuit as it is and outputs 64kHz22.
It is sent as a 04 signal.

The subscriber circuit 44 is a CC engineering TT for the general-purpose modem 24.

It has 24 interfaces. RD401 from the exchange side
The signal KJ:,6 envelope inverter is supplied to an envelope decomposition circuit 420.

The envelope decomposition circuit 420 includes a clock generation circuit 42
The position t of the envelope frame is known from the frame signal from 2, the S bit and the F bit are removed, only the data is extracted, and the data is sent to the general-purpose modem 24 as a 5D211 signal. Table 2 above also shows the correspondence of various data speed changes due to envelope assembly/disassembly. The clock generation circuit 422U creates individual frame clocks using the Rca403 signal, which is the basic frame block, and the strap circuit that defines the data speed.
Create a data timing clock of 11 signals and create 5TI
The signal is supplied to the general-purpose modem 24 as a H.213 signal. Envelope decomposition circuit 420 detects that the S bit in the envelope data of the ViRD401 signal changes from 0" to 1", recognizes this as an incoming call to the data terminal connected to that line, and turns on R8215, that is, ' On the other hand, when the S bit changes from '1' to 0#, it is recognized as the end of the call and the R8215 signal is turned off, that is, set to 0.

The RD212 signal, which is non-enveloped data from the general-purpose modem 24, is sent to the envelope assembly circuit 4.
21. This circuit 421 performs envelope assembly based on the frame clock from the clock generation circuit 422 and supplies envelope data to the subscriber line multiplexing circuit 42. S bit required for assembly is 0D216
obtained from the signal. (When the !D216 signal changes from off to on, it is determined that the call is from a data terminal connected to the line, and the S bit is set to 1".C!D216
When the signal transitions from on to off, it is determined to be disconnected,
Make it S Viratola 10.

Table 1 Table 2 [Effects of the Invention] As explained above, the present invention provides an envelope/non-envelope line connection conversion circuit in an exchange, thereby connecting a general-purpose modem to an envelope-type Mf-to-event exchange. There are effects that can be used for connection. The method of using the carrier signal of a general-purpose modem to disconnect a call may lack serviceability because it takes time for the carrier to turn on (about 1 second), but this method uses the carrier signal of the secondary channel equipped with the general-purpose modem. If used, synchronization is always achieved, so this time problem is solved. On the other hand, analog envelope bearer modems were used at a time when data networks were not digitized, but such modems were expensive. Therefore, it is not advisable to make a large investment in a modem that is used temporarily, and in this respect as well, it is desirable to use a general-purpose modem. Furthermore, even if almost all networks are digitized, the few lines used for terminals in remote areas are often not digitized due to cost considerations, so general-purpose modems are It can be used to great effect.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an exchange network to show the envelope transfer method. FIG. 2 is a diagram showing the format of envelope data. FIG. 3 is a block diagram showing a switching system according to an embodiment of the present invention. FIG. 4 is a diagram showing a detailed block configuration of various signal lines and subscriber circuits 43 and 44. 1...Data terminal, 21, 23...Bearer modem,
22, 24...General purpose modem, 42...Subscriber line multiplex circuit, 43.44...Subscriber circuit, 410...Reception buffer circuit, 411.422...Clock generation circuit, 420... -Envelope decomposition circuit, 421...Envelope assembly circuit. Patent Applicant NEC Corporation Agent Patent Attorney Nao Takashi Ide'j411 Illustration 2

Claims (1)

[Claims] (1) A data line switch that sends and receives envelope data including status bits to and from a synchronous data terminal via a bearer modem, which is equipped with a subscriber circuit that serves as an interface for a general-purpose modem connected to the data terminal, The circuit adds a status bit to the data from the data terminal sent from the general-purpose modem based on the call disconnection information of the general-purpose modem, converts it into an envelope, and sends this envelope 1 data to the exchange side. an envelope assembly circuit that removes status bits from the envelope data sent from the exchange side, converts it into non-envelope data, and sends it to the above-mentioned general-purpose modem, and transmits call disconnection information based on this status bit to the above-mentioned general-purpose modem. and an envelope decomposition circuit for sending data to a data line exchanger.