KR950007502B1 - Multirate access method of modem - Google Patents

Abstract

The modem has multiple bit-rates and accesses other modem by automatically transforming its bit-rate into bit-rate equal to other modem. This modem ascertains bit-rate of other modem and automatically transforms its bit-rate when user doesn't know bit-rate of other modem. If the bit-rate of other modem is below its bit-rate, this modem can access automatically. The method employs a DTE (data terminal equipment)(10), a USART (Universal Synchronous & Asynchronous Receiver & Transmitter), a modem(30), a DAA (Data Access Arrangement) circuit(40), a MPU (Micro Processor Unit)(50), a ROM(60) and a RAM(70).

Description

Multi-Speed Connection Method of Modem

1 is a block diagram of a modem to which the present invention is applied.

2 is a diagram illustrating the internal register of the modem unit 30 in FIG.

3a and 3b are flow charts of a multi-rate connection function in accordance with the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modem (modulator / demodulator), and more particularly, to a multi-rate access method for automatically connecting to a counterpart modem and a transmission rate in a modem having a multi-rate.

In recent years, modems that are widely used with the proliferation of data communication have various transmission speeds, and various kinds of modems according to various standard standards are used. In addition, due to the development of semiconductor design and manufacturing technology and digital signal processing technology, the transmission speed of the modem is gradually increasing due to the technologies that have been impossible in the past. The modem specifications recommended by the CCITT have been developed into V.21 standard of 300bps, V.22 standard of 1200bps, V.22bis standard of 2400bps, and the standard drafts up to V.32 standard of 9600bps.

In general, modems with high speeds are designed to be able to delay all lower speeds. For example, most CCITT-recommended V600-based 9600bps dial-up modems contain transmission rates corresponding to V.22bis, V.22, and V21 specifications.

The speed of modems and the various specifications that accompany them are due to the development of the current dazzling technology, which makes it difficult to implement technologies that were previously difficult to implement gradually and can be implemented at low cost. Because.

Therefore, modems of various transmission speeds and specifications such as 300bps, 1200bps, 2400bps, and 9600bps have been used from modems used in the past. In addition, modems of various transmission speeds and standards cannot communicate unless their speeds and methods are the same. Therefore, the user must set the modem speed to the same as the other party with the existing modem.

In particular, in the CCITT V.32 standard 9600bps dial-up modem using public line, the unspecified number of terminal subscribers who want to communicate with data cannot connect with the other party unless they know the modem specifications or transmission speed of the other party. there was.

Accordingly, an object of the present invention is to provide a modem capable of communicating at any one of the at least three transmission rate standards, even if the modem user does not exactly know the transmission rate of the other party's modem. The present invention provides a multi-speed connection method that can automatically connect any speed within the communication speed of a modem.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a general modem to which the present invention is applied. In FIG. 1, reference numeral 10 denotes a Data Terminal Equipmet (DTE) interface, which adjusts the voltage level or logic state to connect the DTE to the modem as an RS-232C interface. 20 is a Universal Synchronous & Asynchronous Receiver & Transmitter (USART), which allows serial data to be transmitted in parallel and synchronously and asynchronously. The USART 20 is typically used in one chip form. 30 is a modem unit which modulates and demodulates an input / output signal of a modem to a CCITT standard. 40 is a DAA (Data Access Arrangement) circuit, and transmits the analog signal modulated by the modem unit 30 to the public line network, and transmits the analog signal received from the public line network to the modem unit 30, input from the modem unit 30 An internal relay circuit is operated by a pulse dial control signal to transmit a dial pulse signal to a public circuit network, and detects a ring signal received from the public circuit network. The DAA circuit 40 is also connected to a telephone to switch the communication path to a modem or telephone depending on the mode. 50 is an MPU (Micro Processor Unit), which controls the USART 20, the modem unit 30, and the DAA circuit 40 as a whole, and has a built-in timer inside to delay or give up during program execution. Used to control the abort time. 60 indicates a modem control program of the MPU 50 as a ROM. 70 denotes a RAM and stores processing data according to program execution of the MPU 50.

FIG. 2 is an internal register configuration diagram of the modem unit 30 in FIG. 1, wherein a register and a flag and a modem unit 30 for controlling the modem unit 30 in the MPU 50 are shown in FIG. Figure 1 shows an example in which the modem of FIG. 1 is a dial-up modem of CCITT V.32 standard having a transmission rate of 9600bps.

Figure 3a is a flow chart of the multi-rate connection function in the origin mode according to the present invention, by controlling the register and flag of the modem unit 30 and the DAA circuit 40, by the call progress process and the public line network and line By connecting and controlling the registers and flags of the modem unit 30, the modem unit 30 is initialized to the transmission mode of the highest transmission rate among the communication speeds that can be communicated with each other so as to perform handshaking with the relative response modem. And from the registers and flags of the modem unit 30 whether a handshake signal of which transmission rate standard among the handshake signals for each transmission rate standard is detected in the signal received from the response modem according to the handshaking. Confirming the transmission rate specification of the relative response modem, and controlling the registers and flags of the modem unit 30 to determine the transmission rate specification of the identified relative response modem. The modem unit 30 is set at a transmission rate of the same standard as that of the standard.

Figure 3b is a flow chart of the multi-speed connection function in the answer mode according to the present invention, in response to the modem unit 30 detects the ring signal received from the public circuit network and the register of the modem unit 30 and Initializing the modem unit 30 to the response mode of the highest transmission rate among the communication rate standards by controlling the flag, and controlling the DAA circuit 40 to connect the line of the public line network and register the register of the modem unit 30. And handshaking with the other calling modem after transmitting a response tone by controlling a flag; and in the signal received from the other calling modem according to the handshaking, one of the transmission signal standards according to the data rate standard Checking whether a handshake signal is detected from a register and a flag of the modem unit 30 to confirm a transmission rate specification of the other calling modem; By controlling the register and the flag, the modem unit 30 is set at a transmission rate of the same standard as that of the identified transmission source modem, and the connection is made with the other transmission modem.

Hereinafter, an operation of an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3A and 3B.

First, the modem unit 30 of FIG. 1 is typically a modem set composed of a plurality of VLSI chips and peripheral circuits for digital signal processing (DSP) processing, and the MPU 50 for controlling the modem set is a modem. Various terminals external to the set: power supply voltage terminal (Vcc), ground terminal (GND), read enable terminal (RD), write enable terminal (WR), chip select enable terminal (CS), data bus The modem set is operated using a terminal such as (DATA), an address bus ADDR, an analog signal transmitting terminal TXA, an analog signal receiving terminal RXA, and the register of FIG. 2 inside the modem set.

In the following description, the modem of FIG. 1 is a CCITT V.32 dial-up modem having a transmission rate of 9600 bps. The V.32 standard dial-up modem supports not only 9600bps but also V.21 at 300bps, V.22 at 1200bps, and V.22bis at 2400bps.

In addition, according to each transmission speed of modem, when modem is connected, both modems handshaking each other to adjust various parts such as clock, filter, equalizer and adapt to signal status. The initial values and variables are determined as possible.

Therefore, the present invention is to determine the status of the modem of the other party in the handshake method determined by each transmission rate standard to connect the transmission rate that meets the standard.

In general, an operation mode of a modem is divided into an outgoing mode that operates as a calling modem and a response mode that operates as a response modem.

First, when the modem of FIG. 1 calls the other party, the other party's modem is in response mode. The operation of the transmission mode in which the transmission speed of the other modem, that is, the response modem is detected, is described as follows.

According to the CCITT Recommendation, since the calling modem is transmitting in calling mode, the MPU 50 of FIG. 1 performs dial tone checking, dialing, ringback tone checking, busy tone checking, public rotating network and line in step 101 of FIG. (line) Call process such as connection.

The call progress process is performed as follows. When the MPU 50 writes a value corresponding to the dialing operation (for example, 81H in hexadecimal value) to TCONF of the register R1 as shown in FIG. 2 of the modem unit 30, the modem unit 30 causes the DAA circuit ( Dialing operation is performed through 40). At this time, DTMF dialing with D5 bit of register R4 is set to # 1, and DTMF dialing with D5 bit of register R4 is set to # 0 "to perform pulse dialing. In the TBUF of the register R1, when the modem unit 30 is to dial, a value corresponding to the dialing digit (for example, 05H as a hexadecimal value when the digit is 5) is written. At the time of transmission, the data to be transmitted is written.

Next, in step 102, the modem unit 30 is set to the V.32 calling mode and initialized. At this time, if the ORG flag, which is the D4 bit of the register R4, is set to '1', the modem unit 30 operates in the transmission mode, and the value corresponding to the V.32 configuration in TCONF of the register R2 ( For example, in case of V.32 mode, 74H) is written in hexadecimal, and modem unit 30 operates in V.32 mode. When DATA0 flag, D2 bit of register (R3) is set to '0', modem The unit 30 is initialized to operate in the V.32 origination mode.

After setting the internal abandon timer for aborting when the connection with the other party or the carrier signal is not detected in step 103, the time elapses in steps 104 and 108. (time over), the response tone detection, the AC signal detection, the USB1 (Unscramble Binary1) signal detection, and the FSK signal detection that can be received by the modem unit 30 from the counterpart modem are checked. The AC signal is a segment signal of a part of a handshake signal transmitted in a response mode of a V.32 modem, and the USB1 signal is a segment signal of a part of a handshake signal transmitted in a response mode of a V.22bis modem. The FSK signal is a carrier signal transmitted in response mode of the V.21 modem. The AC, USB1 and FSK signals are recommended in CCITT V.32, V.22bis and V.21, respectively. Whether or not the response tone is detected in step 105 is checked by checking the ATV25 flag, which is the D3 bit of the register R9. If it is set to ˝1˝, the response tone is detected, and the AC signal is detected in step 106. Whether or not the AC signal is detected by checking the AC flag, which is the D6 bit of the register R9, if it is set to '1', the detection of the USB1 signal in step (107) is the D1 bit of the register R9. When USB1 flag is checked and checked, if USB1 signal is set, USB1 signal is detected. Whether FSK signal is detected in step (108) is checked by checking V21 flag, D2 bit of register (R9). If set to, the FSK signal has been detected. That is, the modem unit 30 detects that the signals are received through the public line network and the DAA circuit 40 and sets the corresponding flag of the internal register as described above, and the MPU 50 checks the signals. It is to check whether they are detected.

If a response tone is detected in step 105 before the abandon time elapses in step 104, the process proceeds to step 110, and after a delay of 1 second using an internal timer, in step 111, the register ( Set the DATA0 flag, which is the D2 bit of R3) to # 1, so that the modem unit 30 starts transmitting the AA signal to start the handshake. In step 112, it is checked whether the response tone is finished. The termination tone response may be delayed by the transmission time of the response tone specified in the CCITT standard.

When the response tone ends in step 112, the abandon timer is set again in step 113, and then time passes, AC signal detection, USB1 signal detection, and FSK signal detection are checked at (114)-(117). .

When the USB1 signal is detected in step 116, the USB1 signal is transmitted in the V.22bis or V.22 mode. Therefore, it is determined that the relative modem is not in the V.32 mode. Set the DATA2 flag, D2 bit, to '0' to stop sending the AA signal at the same time as the V.32 handshake is stopped. Next, in step (119), it is checked whether the USB1 signal is finished. To terminate the USB1 signal, it is checked whether the USB1 flag, which is the D1 bit of the register R9, is set to '0'. After resetting the abandon timer in step 120, the USB1 signal is detected as described above. Therefore, it is determined that the relative modem is in V.22bis mode or V.22 mode and the time elapses in steps 121-123. Check whether the S1 signal is detected and the SB1 signal is detected. The S1 signal is a segment signal of a part of a handshake signal transmitted in a response mode of a V.22bis modem, and the SB1 signal is a segment of a part of a handshake signal transmitted in a response mode of a V.22 modem. The S1 and SB1 signals are recommended in CCITT V.22bis and V.22, respectively. Whether or not the S1 signal is detected in step 122 is checked whether the S1 flag, which is the D5 bit of the register R9, is set to '1', and whether or not the SB1 signal is detected in step 123 is the D4 bit of the register R9. It is checked whether or not the detected SB1 flag is set to '1'.

When the AC signal is detected in the step 106 or the AC signal is detected in the step 115, since the relative response modem has a 9600bps transmission rate of V.32 standard, after transmitting the AA signal in the step 106, Proceeding to step (124), in step 115, since the AA signal is being transmitted, proceed to step (124) as it is, and set the modem unit 30 in the V.32 call mode in step 125. Make handshaking with the opposing modem in V.32 mode.

When the USB1 signal is detected in step (107) or the USB1 signal is detected in step (116), the answer modem determines that it is a V.22bis or V.22 standard modem, and steps (118) to (123). Perform When the S1 signal is detected in step 122, the upper response modem has a 2400 bps transmission rate of the V.22bis standard, and then proceeds to step 126 to set the modem unit 30 in the V.22bis transmission mode (127). In the) step, handshak with the opponent modem in V.22bis mode. In addition, if the SB1 signal is detected in step 123, the relative response modem has a 1200 bps transmission speed of V.22 standard. Therefore, proceed to step 128 and set the modem unit 30 in the V.22 transmission mode. Step 129) handshaking with the opposing modem in V.22 mode.

When the FSK signal is detected in step (108) or step (117), the relative response modem has a 300bps transmission speed of V.21 standard. Therefore, the process proceeds to step 130 and the modem unit 30 enters the V.21 transmission mode. After set, perform handshaking with the opponent modem in V.21 mode in step (131).

The mode setting of V.32, V.22bis, V.22, and V.21 is to set configuration values of each mode in TCONF of register R2 and RCONF of register R3. Is the V.32 configuration value (eg 74H), V.22bis mode setting is the V.22bis configuration value (eg 84H), V.22 mode setting is the V.22 configuration value (eg 82H), For mode setting, enter the V.21 configuration value (eg AψH). In addition, outgoing mode setting is done by setting ORG flag, which is D4 bit of register (R4), to '1'.

In step 125, 127, 129, and 131, the handshaking of each mode is set to the respective mode, and then the DARA0 flag, which is the D2 bit of the register R3, and the D2 bit of the register R7, are set. By setting the DATA1 flag as # 1, the modem unit 30 handshaking with the other modem.

Next, in step 132, the abandon timer is set again, and then in step 133, it is checked whether the time elapses and in step 134, whether the DCD (Data Carrier Detector) is turned on. In step (134), whether the DCD turns on or not is checked by checking the DCD flag, which is the D7 bit of the register R8, if it is set to '1', the DCD determines that the DCD is turned on. When the DCD is turned on in step 134, the connection with the other modem is completed. In step 135, the modem connection is completed. At this time, because it knows the set according to the modem specification can inform the user of the other party and the connection speed.

In addition, when the connection is completed in step (135), the modem unit 30 operates in the data transmission mode in step 136, and when the data transmission is completed, proceeds to step 137 to hang up the line with the public circuit network. Disconnect and terminate the connection.

On the other hand, if the abandon time elapses in steps 104, 114, 121, and 133, the other party does not connect or detects the carrier signal of the other party within the designated time (138). In step), the non-signal is displayed and the process proceeds to step 137 to hang up.

Herein, the modem connection completion indication of step (135) and the no signal indication of step (138) are the DTE interface 10, and the connection completion message or the no-signal message is transmitted using an ASCII code or the like through the RS-232C interface. To be displayed on the DTE's screen or known by the DTE's MPU. In addition, the data transmission in the step (136) is to transmit the data transmitted from the DTE by the modem unit 30 to the counterpart modem when the connection is complete after the handshaking with the counterpart modem is completed, in step (137) The relay of the DAA circuit 40 is controlled by the hook control signal of the hangup, and is on-hook after completion of data transmission.

Secondly, when the modem of FIG. 1 operates in the answer mode, the operation of the answer mode in which the transmission speed of the relative modem, that is, the calling modem is detected, is described as follows.

The MPU 50 of FIG. 1 checks whether the ring signal is detected in step 201 of FIG. 3B. The MPU 50 checks the R1 flag, which is the D3 bit of the register R11 as shown in FIG. When set to 0, the ring signal is detected. If a ring signal is detected, the modem unit 30 is initialized by setting the V.32 response mode in step 202, and then the line is controlled and the line is connected in step 204 in step 203. Start sending response tone. Setting to the V.32 mode is as described above, and the response mode is to set the ORG flag, which is the D4 bit of the register (R4) to '0'. When the modem unit 30 is set to the answer mode, when the modem unit 30 is set to the answer mode, the modem unit 30 transmits the response tone and continues handshaking when the DATA0 flag, which is the D2 bit of the register R3, is set to # 1. Will be

Next, in step 205, a response tone sending time timer is set, and in step 206, it is checked whether time elapses and in step 207, whether an AA signal is detected.

If the AA signal is detected in step 207 before the response tone transmission time ends, it is determined that the relative modem is in the V.32 transmission mode and the process proceeds to step 214.

If the AA signal is not detected until the response tone transmission is completed in step 206, after setting a no-signal timer in step 208, time elapses, AA signal detection, and S1 signal detection in steps 209 to 213. Check if SB1 signal is detected or FSK signal is detected.

The AA signals in steps 207 and 210 are segments of a handshake signal transmitted by the V.32 modem in the transmission mode, and the S1 signal in step 211 is transmitted by the V.22bis modem in the transmission mode. A part of the handshake signal is a segment signal, the SB1 signal in step (212) is a segment signal of a part of the handshake signal transmitted by the V.22 modem in the transmission mode, and the FSK signal in step (213) is a V.21 modem. Carrier signals transmitted in this transmission mode, each recommended in CCITT V.32, V.22bis, V.22, and V.21.

When the AA signal is detected in step (207) or step (210), since the counterpart modem has a 9600bps transmission speed of V.32 standard, it proceeds to step 214 and has a 9600bps transmission speed of V.32 standard ( In step 214, the modem unit 30 is set in the V.32 answer mode, and in step 215, handshaking with the counterpart modem is performed in the V.32 mode.

When the S1 signal is detected in step 211, the counterpart modem has a 2400 bps transmission speed of the V.22bis standard. Therefore, the process proceeds to step 216. After setting the modem unit 30 in the V.22bis response mode (217). In the) step, handshaking with the other modem in V.22bis mode.

When the SB1 signal is detected in step 212, the transmission modem has a 1200 bps transmission speed of V.22 standard. Therefore, the process proceeds to step 218 and sets the modem unit 30 in the V.22 response mode. In the) step, handshak with the other modem in V.22 mode.

If the FSK signal is detected in step (213), since the calling modem has a V.21 standard having a 300bps transmission rate, the process proceeds to step 220 and sets the modem unit 30 in the V.21 response mode (221). In the) step, handshak with the opponent modem in V.21 mode.

On the other hand, after performing steps 215, 217, 219, and 221, the process proceeds to step 222 to perform steps 222 to 228, and when time elapses from step 209. Performing steps 228 and 227 is the same as in steps 132 to 138 of FIG.

Therefore, even if the user does not know the transmission speed of the other party's modem in outgoing mode or response mode, the transmission speed of the other party's modem is automatically checked and automatically connected when it is included in its own transmission speed.

As described above, the present invention provides a modem capable of communicating at any one of the at least three transmission rate standards, so that the connection can be performed at the same transmission speed as the other modem even if the transmission speed of the other modem is not known accurately. It reduces the modem connection time, does not need to have a variety of modems, and the advantage of eliminating the inconvenience of trying to reconnect by checking the transmission speed again when the connection is attempted at a separate speed.

Claims (6)

In a multi-rate connection method of a modem capable of communicating at any one transmission rate set among at least three transmission rate specifications each having a different transmission rate specification for each transmission rate specification, the modem is connected to a public line network by a call progression process. And a process of performing line connection, and initializing the modem to a transmission mode of the highest transmission rate standard among the communicable transmission rate standards to perform handshaking with the response modem, and from the relative response modem according to the handshaking. Checking the transmission rate specification of the relative response modem by checking which of the handshake signals of the transmission rate specifications is detected in the received signal and transmitting the identified relative response modem; Setting the modem to a transmission speed of the same standard as the speed standard and An originating mode access process comprising a process of connecting to a response modem, initializing the modem to a response mode of the highest transmission rate among the communication rate standards that can be communicated in response to detection of a ring signal received from the public line network; Connecting the modem to the public line network, transmitting a response tone, and handshaking with the other calling modem; and a handshake signal according to the transmission rate standard in the signal received from the calling modem according to the handshaking. Checking the transmission speed standard of the counterpart transmission modem by checking which of the transmission speed standards is detected, and executing the modem at a transmission speed of the same standard as that of the identified transmission modem. A response mode approach consisting of a process of connecting to the other party's calling modem by setting Multi-speed connection method of a modem, characterized in that it comprises a fast process. The method of claim 1, wherein the transmission rate specifications are each one of V.32, V.22bis, V.22, and V.21 specifications according to CCITT Recommendations. A data terminal interface connected to a data terminal device, a DAA circuit connected to a public line network, an MPU with a built-in timer, and a plurality of signals for demodulating and transmitting and receiving signals through the line network under the control of the MPU. A modem unit having a register and a flag and a plurality of flags indicating various states, each of which is capable of communicating at any one transmission rate set among at least three transmission rate standards having a handshake signal for each transmission rate specification. In the multi-speed connection method in the outgoing mode, the method includes controlling a register and a flag of the modem unit and a DAA circuit to perform a line connection with the public line network through a call progression process, and control the register and a flag of the modem unit to communicate the modem unit. Transmission of the highest transmission rate among the possible transmission rate specifications Initializing the handset to perform handshaking with a counterpart response modem, and determining a handshake signal of a transmission speed standard among the transmission speed standard-specific handshake signals in a signal received from the response modem according to the handshaking. Checking the transmission rate specification of the relative response modem by checking from the register and the flag of the modem unit; and controlling the register and the flag to the modem unit to control the register and the flag at the transmission rate of the same standard as that of the confirmed relative response modem. And a modem unit is set to connect with the counterpart answering modem. 5. The method of claim 4, wherein the standards are any one of V.32, V.22bis, V.22, and V.21 standards according to the CCITT Recommendation. A data terminal interface connected to a data terminal device, a DAA circuit connected to a public line network, an MPU with a built-in timer, and a plurality of signals for demodulating and transmitting / receiving signals through the public line network under control of the MPU. A modem having a register and a flag and a modem section having a plurality of flags indicating various states, each of which is capable of communicating at any one transmission rate set among at least three transmission rate specifications having a handshake signal for each transmission rate specification. In the multi-rate access method in response mode of the communication mode, the modem unit transmits the highest transmission rate among the transmission rate standards that the modem unit can communicate by controlling registers and flags of the modem unit in response to detecting the modem unit detecting a ring signal received from the public line network. Initialization in response mode of speed and phase Controlling a DAA circuit in line with the public line network, controlling a register and a flag of the modem unit to send a response tone, and then handshaking with the other calling modem; and receiving from the other calling modem according to the handshaking. Checking a transmission rate standard of the counterpart modem by checking a register and a flag of the modem unit in which a handshake signal of the transmission rate standard is detected among the handshake signals for each transmission rate standard in the signal; Controlling a register and a flag of a negative terminal to set the modem unit at a transmission rate of the same standard as that of the identified relative response modem, and connecting to the relative originating modem. . 8. The method of claim 7, wherein the standards are any one of V.32, V.22bis, V.22, and V.21 specifications according to CCITT Recommendations, respectively.