JPH0897801A - Error character detection method for telex communication - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to provide an error character resending protocol that enables automatic error detection, automatic error notification, and automatic resending by improving the transmitting side telex terminal and the receiving side telex terminal. To do. [Structure] A character string of a telegram to be transmitted is divided line by line from a transmission side terminal, an error detection additional code is added to each line, and the error detection addition code is transmitted to the reception side terminal. In the error character detection method for telex communication characterized by determining whether the code is normal for each line, as the error detection additional code, a check sequence in the CRC method is used after being converted into a character string, or BCC
It is characterized in that the value obtained by the parity check function according to the method is converted into a character string and used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error character detection system for telex communication. More specifically, the present invention relates to a character detection method by which the receiving side can automatically determine the presence or absence of garbled characters.

[0002]

2. Description of the Related Art In telex communication, if noise is mixed or a momentary interruption occurs during transmission, a phenomenon of receiving a character different from a transmitted character, so-called garbled character, may occur. Currently, international / domestic public telex communication is often used for important communications for business transactions, etc., and garbled characters may continue to cause great damage, so garbled characters are still important. It's a problem.

Therefore, in the telex communication, when exchanging a message containing an important character string, the receiver needs to pay attention to whether the message is garbled.
To reduce this work, a simple correlation (Cor
By the method called "relation", a method of manually detecting an error in a telegram was adopted. This correlation is a method in which the same number or the like as an important number or the like in a telegram is repeated at the end of a sentence, the two are compared on the receiving side, and when different, it is recognized as garbled.

Here, the telex communication will be briefly described. In the telex communication system, internationally,
The start-stop synchronization type 5 unit printing telegraph signal shown in FIG. 8 is used. The printing telegraph signal employs a cadence synchronization method in which the start element and the stop element synchronize each character between the transmitting side and the receiving side. The same polarity as the start element is called A polarity, and the same polarity as the stop element is called Z characteristic.

As the print telegraph code, the second international telegraph alphabet (International Telegaph Alpha) shown in FIG. 9 is used.
bet No.2: ITA No.2) is used. For example, the code number (Comb. No.) 27 means return (CARR. RET.), And the code number (Comb. No.) 28 means line feed (LINE FEED). on the other hand,
In the domestic telex communication system, in addition to the characters handled by the 5-unit signal, kana characters are handled, so a 6-unit character signal that can have a larger code number than the 5-unit character is used.

[0006]

However, in the above-mentioned correlation, since the error of the electronic message is manually detected, the garbled character cannot be surely detected, and there is a certain limit. In telex communication,
As with other communication methods, there is an urgent need to improve communication quality. On the other hand, nowadays, with the development of computer technology, the telex terminal has been changed from a mechanical type to a programmable electronic type, and the connection with a personal computer has become widespread.

The present invention has been made in view of the above-mentioned prior art, and by improving the transmitting side telex terminal and the receiving side telex terminal, an error that enables automatic error detection, automatic error notification and automatic resending. The purpose is to provide a character detection method.

In the present invention, an "error" in a telex message is defined as a "garbled character" unless otherwise specified. In addition, "error" is used in a generally defined meaning ("Iwanami Information Science Dictionary" May.1990. Iwanami Shoten). That is, the “error” means a deviation from the specified content or a state that is logically correct. It is erroneous that is manifested because the components of the failed system are used unmasked. Eliminating the fault that causes the error is a fundamental measure, but in addition to this, when an error is detected, an error detection signal such as a parity bit is used to specify the error in the specified content or logic. Error correction to restore the correct state. If these treatments do not help, there will be obstacles.

[0009]

The structure of the error character detection system for telex communication of the present invention which achieves the above object is obtained by adding an error detection additional code to a character string of a message to be transmitted from a transmission side terminal and receiving it. It is characterized in that it is transmitted to the side terminal and the reception side terminal judges whether or not the error detection additional code is normal. Further, the configuration of the error character detection method for telex communication of the present invention to achieve the above object, the character string of the message to be transmitted is divided line by line from the transmitting terminal, the error detection additional code is added to each line Then, it is transmitted to the receiving side terminal, and the receiving side terminal determines whether or not the error detection additional code is normal.

Here, when the receiving side terminal determines that the error detecting additional code is not normally received,
An error notification is sent back to the sending terminal, and when the sending terminal receives the error notification from the receiving terminal, the character string of the message to be sent is re-written. It is characterized by transmitting. Further, when the receiving side terminal determines that the error detecting additional code is normally received, with respect to the transmitting side terminal,
Characterized by returning a notification without error.

Further, as the error detection additional code, CR is used.
It is characterized in that the check sequence in the C method is used after being converted into a character string, or the value obtained by the parity check function by the BCC method is converted into a character string and used.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 shows an error character resending protocol (Error Fres) for telex communication according to an embodiment of the present invention.
e Telex Protocol: hereinafter referred to as EFTP protocol)
Indicates. In this embodiment, a CRC error detection addition code is applied.

[Protocol Element] Here, the protocol element is defined as follows. REQ00: Error character retransmission protocol start instruction (1 time full text retransmission) REQ10: Error character retransmission protocol start instruction (N times full text retransmission) REQ01: Error character retransmission protocol start instruction (1 line 1 time retransmission) REQ11: Error character retransmission protocol start Indication (retransmission of one line N times) REP: Retransmission display ACK: Notification of no error NAK: Notification of error C = (c ₁ , c ₂ , ..., C _m ): Error detection additional code (including identification header)

[Protocol Sequence] EF of this Embodiment
The TP protocol communication method is basically performed according to the flowchart of FIG. First, after the end-end line setting is completed, the error retransmission protocol start instruction REQ ** of this embodiment is transmitted from the transmitting side to the receiving side. RE
Q ** is REQ00, REQ10, REQ01
Or, there are four types of REQ11.

Next, the transmission side starts the transmission of the telex message and the calculation of the error detection additional code C of the CRC method. Also, the receiving side starts receiving the telex message from the transmitting side. Here, in the case of international telex communication, the telegram to be transmitted is represented by a 5-unit code as shown in FIGS. 8 and 9. Therefore, since one character is represented by 5 bits, a character string which is a telegram to be transmitted is represented by a bit string in which 5 bits of each character are continuously arranged.

A method of calculating the error detection additional code C by the CRC method will be briefly described. The bit string to send
_Let b ₁ , b ₂ , ... B _n, and define P (X) as follows. However, b _i is 1 or 0 (i = 1 to n). P (X) = b ₁ X ^n-1 + b ₂ X ^n-2 + ... + b _n-1 X + b _n (1) Further, G (X) is defined as follows. G (X) = a ₁ X ^m + a ₂ X ^m-1 + ... + a _m-1 X + am (2) where a _i is 1 or 0 (i = 1 to _m + 1).

Here, P (X) is multiplied by X ^m to obtain G (X)
If the remainder when divided by is R (X), R (X) can be expressed as the following equation. R (X) = c ₁ X ^m-1 + c ₂ X ^m-2 + ... + c _m-1 X + c _m (3) The bit string C = (c ₁ , c ₂ , ... C _m ) at this time is a check sequence. Therefore, in this embodiment, it is used as an error detection additional code. This G (X) is referred to as a check sequence generator polynomial, and is referred to as ITU-T Recommendation V.6. In 24, the following equation is recommended. G (X) = X ¹⁶ + X ¹² + X ⁵ +1 (4)

The check sequence C generated by the generator polynomial of the equation (4) has 16 bits. This is ITA
It is necessary to characterize with No.2. Therefore, in order to represent 16 bits by 26 letters of the alphabet, 16 bits are divided into 4 bits + 4 bits + 4 bits + 4 bits, and each 4 bits are associated with 16 kinds of alphabets A to P. That is, the check sequence C is represented by the four-letter alphabet.

As described above, in the CRC method, the error detection additional code C represented by four characters is obtained for each bit string to be transmitted, and the error detection additional code C can be transmitted as a character. As another method, as will be described later, BC
The C method may be used.

However, when the character string of the electronic message to be transmitted extends over a plurality of lines, they are divided line by line to obtain the error detection additional code C. That is, the bit string is a bit string in which the respective bits (5 bits) of the character string from the new line to the new line are arranged continuously, and the error detection additional code C is obtained for each bit string. Therefore, for each line of message,
The 4-character error detection additional code C is added.

Subsequently, after the transmission and reception of the telex message are completed, the transmitting side transmits the error detection additional code as the character string C, and the receiving side receives the character string C. Here, since the character string C has four characters per line of the electronic message, when the electronic message extends over a plurality of lines, the number of lines is doubled. For example, if the message is 3 lines, 4 × 3 = 12 characters.

After that, the receiving side divides the received character string C, which is the error detection additional code, into the character strings (4 characters) generated corresponding to each line of the electronic message. This is converted into a bit string, and the value obtained by arithmetically adding the result of converting the character string of the relevant line of the electronic message into the bit string is divided by the generator polynomial G (X) to determine whether the remainder becomes 0 or not. If the remainder is 0, it has been normally received, that is, it is determined that it is OK. Therefore, the error-free display ACK is returned from the reception side to the transmission side, and the transmission side receives the error-free display ACK and the line is connected. Perform recovery processing. On the other hand, if the remainder is not 0, it is determined that the reception has not been normally performed, that is, the characters are garbled, and therefore an error presence display NCK is returned from the reception side to the transmission side.

The transmitting side, which has received the error indication NCK,
The sender side adds a resend display REP to the telex message and resends it to the receiver side.
The EP is received and the line is restored. The message to resend is
The full text of the message may be used, or only the line containing the error may be resent. The line containing an error can be determined by where in the character string C there is an error. Also, depending on the communication conditions, there may be an error in the re-transmission text, so the retransmission is not limited to once, and may be repeated multiple times if necessary.

As described above, in the present embodiment, the receiving side can automatically notify the transmitting side that an error exists while the line is held, and the transmitting side which has received the notification can notify the line. It is possible to automatically resend the same message while holding. In order to realize the above EFTP protocol, it is necessary to add software to the sending side terminal and the receiving side terminal, but the public telex network does not need any additional function and is highly versatile.

Further, as will be described later, it is possible to communicate between a sending side terminal equipped with the EFTP protocol and a receiving side terminal not equipped with the EFTP protocol.
In the terminal equipped with the TP protocol, it is not necessary to change the parameter settings for masking the EFTP protocol. Next, specific examples of the present invention will be described.

[Embodiment 1] As shown in FIG. 2, this embodiment 1 is a protocol for retransmitting the entire text of an electronic message only once when there is an error. That is, it is a one-time full-text retransmission protocol (REQ00). First, after the end-end line setting is completed, the error retransmission protocol start instruction REQ00 of this embodiment is transmitted from the transmitting side to the receiving side. Next, start sending the telex telegram from the sender and CRC
The calculation of the error detection additional code C of the method is started. Also, the receiving side starts receiving the telex message from the transmitting side.

Thereafter, after the transmission side has completed the transmission of the telex message and the reception side has completed the reception of the telex message, the transmission side transmits the error detection additional code as the character string C, and the reception side Receive the character string C. Subsequently, on the receiving side, the character string C, which is the received error detection additional code, is generated corresponding to each line of the electronic message (4
Character). This is converted to a bit string, and the value obtained by arithmetically adding to the result of converting the character string of the relevant line of the message to the bit string,
It is divided by the generator polynomial G (X), and it is determined whether the remainder becomes 0 or not.

If the remainder is not 0, it is determined that the reception has not been normally performed, that is, the characters are garbled, and therefore an error presence indication NCK is returned from the reception side to the transmission side. The sending side, which has received the error indication NCK, adds a resend indication REP to the telex telegram (full text) from the sending side and resends it to the receiving side, and the sending side retransmits text (full text) and resend indication R.
The EP is received and the line is restored.

[Embodiment 2] In Embodiment 2, as shown in FIG. 3, when there is an error, the entire text of the electronic message is repeated a plurality of times (N times).
It is a protocol for resending. That is, it is the N times full-text retransmission protocol (REQ10). First, after the end-to-end line setting is completed, the error retransmission protocol start instruction REQ10 of this embodiment is transmitted from the transmitting side to the receiving side.

Next, transmission of the telex telegram is started from the transmitting side, and calculation of the CRC error detection additional code C is started. Also, the receiving side starts receiving the telex message from the transmitting side. Then, after the transmission side completes the transmission of the telex message and the reception side completes the reception of the telex message, the transmission side transmits the error detection additional code as a character string C, and the reception side receives the character string C. To receive.

Subsequently, on the receiving side, the received character string C, which is the error detection additional code, is divided into character strings (4 characters) generated corresponding to each line of the electronic message. This is converted into a bit string, and the value obtained by arithmetically adding the result of converting the character string of the relevant line of the electronic message into the bit string is divided by the generator polynomial G (X) to determine whether the remainder becomes 0 or not. If the remainder is not 0, it is determined that the error has not been received normally, that is, the garbled character is present, and therefore the error display NCK is returned from the receiving side to the transmitting side. Receiving the error indication NCK, the sending side resends the telex message (full text) from the sending side to display RE.
P is added and retransmitted to the receiving side, and the receiving side receives the re-transmitted text (full text) and the resend indication REP. Further, the character string C is transmitted from the transmission side to the reception side as the error detection additional code.

Further, on the receiving side, the character string C which is the received error detection additional code is divided into character strings (4 characters) generated corresponding to each line of the electronic message. Convert this into a bit string,
The value obtained by arithmetically adding the bit string of the character string of the relevant line of the message is divided by the generator polynomial G (X), and the remainder is 0.
It is determined by whether or not If the remainder is not 0, it is determined that the message has not been normally received. Therefore, after repeating the retransmission of the electronic message (entire text) a plurality of times (N times),
Restore the line.

[Third Embodiment] As shown in FIG. 4, the third embodiment is a protocol for retransmitting only the line in which there is an error in the electronic message only once when there is an error. That is, 1
It is a one-time retransmission protocol (REQ01). First, after the end-end line setting is completed, the error retransmission protocol start instruction REQ01 of this embodiment is transmitted from the transmitting side to the receiving side.

Next, the transmission side starts the transmission of the telex message and the calculation of the error detection additional code C of the CRC method. Also, the receiving side starts receiving the telex message from the transmitting side. Then, after the transmission side completes the transmission of the telex message and the reception side completes the reception of the telex message, the transmission side transmits the error detection additional code as a character string C, and the reception side receives the character string C. To receive.

Subsequently, the received character string C, which is the additional code for error detection, is divided into the character strings (4 characters) generated corresponding to each line of the electronic message. This is converted into a bit string, and the value obtained by arithmetically adding the result of converting the character string of the relevant line of the electronic message into the bit string is divided by the generator polynomial G (X) to determine whether the remainder becomes 0 or not. If the remainder is not 0, it is determined that the error has not been received normally, that is, the garbled character is present, and therefore the error display NCK is returned from the receiving side to the transmitting side. Upon receiving the error indication NCK, the sending side sends a resend indication R to the line containing the error in the telex message from the sending side.
EP is added and retransmitted to the receiving side, and the receiving side receives the re-transmitted text (one line) and the retransmission indication REP, and restores the line.

[Embodiment 4] As shown in FIG. 5, this Embodiment 4 is a protocol for retransmitting only a line in which there is an error in a message a plurality of times (N times) when there is an error. That is, it is the N-times one-line retransmission protocol (REQ11). First, after the end-to-end line setting is completed, the error retransmission protocol start instruction REQ11 of this embodiment is transmitted from the transmitting side to the receiving side.

Next, the transmission side starts the transmission of the telex telegram, and at the same time, the calculation of the CRC system error detection additional code C is started. Also, the receiving side starts receiving the telex message from the transmitting side. Then, after the transmission side completes the transmission of the telex message and the reception side completes the reception of the telex message, the transmission side transmits the error detection additional code as a character string C, and the reception side receives the character string C. To receive.

Subsequently, on the receiving side, the character string C, which is the error detection additional code obtained by the operation, is compared with the received character string C, which is the error detection additional code, and it is determined whether or not they match. To do. The received character string C, which is the error detection additional code, is generated in correspondence with each line of the electronic message (4
Character). This is converted to a bit string, and the value obtained by arithmetically adding to the result of converting the character string of the relevant line of the message to the bit string,
It is divided by the generator polynomial G (X), and it is determined whether the remainder becomes 0 or not. If the remainder is not 0, it is determined that the error has not been received normally, that is, the garbled character is present, and therefore the error display NCK is returned from the receiving side to the transmitting side.

The transmitting side, which has received the error indication NCK,
From the transmitting side, a retransmission indication REP is added to the line in which there is an error in the telex message and is retransmitted to the receiving side, and the receiving side receives the re-transmitted statement (one line) and the retransmission indication REP. Further, the character string C is transmitted from the transmission side to the reception side as the error detection additional code. Further, on the receiving side, the received character string C, which is the error detection additional code, is divided into character strings (4 characters) generated corresponding to each line of the electronic message. This is converted into a bit string, and the value obtained by arithmetically adding the result of converting the character string of the relevant line of the electronic message into the bit string is divided by the generator polynomial G (X) to determine whether the remainder becomes 0 or not.

If the remainder is not 0, it is determined that the message has not been normally received, that is, the characters are garbled. Therefore, after the message (one line) is retransmitted a plurality of times (N times) as described above, , Recover the line.

[Embodiment 5] As shown in FIG. 6, Embodiment 5 is a sequence in the case where the receiving side is a normal terminal not equipped with the EFTP protocol. First, after the end-end line setting is completed, the error retransmission protocol start instruction REQ ** of this embodiment is transmitted from the transmitting side to the receiving side.

Next, transmission of the telex message is started from the transmitting side, and calculation of the error detection additional code C of the CRC system is started. Also, the receiving side starts receiving the telex message from the transmitting side. Then, after the transmission side completes the transmission of the telex message and the reception side completes the reception of the telex message, the transmission side transmits the error detection additional code as a character string C, and the reception side receives the character string C. To receive.

Next, since the receiving side does not have the EFTP protocol, the line is restored after a lapse of a fixed time without performing any processing on the received character string C which is the error detection additional code.

[Sixth Embodiment] As shown in FIG. 7, the sixth embodiment is a sequence when there is no error. First, after the end-end line setting is completed, the error retransmission protocol start instruction REQ ** of this embodiment is transmitted from the transmitting side to the receiving side. Next, the transmission side starts transmitting the telex message and the calculation of the CRC error detection additional code C at the same time. Also, the receiving side starts receiving the telex message from the transmitting side.

Thereafter, after the transmission side has completed the transmission of the telex message and the reception side has completed the reception of the telex message, the transmission side transmits the error detection additional code as the character string C, and the reception side Receive the character string C. Subsequently, on the receiving side, the character string C, which is the received error detection additional code, is generated corresponding to each line of the electronic message (4
Character). This is converted to a bit string, and the value obtained by arithmetically adding to the result of converting the character string of the relevant line of the message to the bit string,
It is divided by the generator polynomial G (X), and it is determined whether the remainder becomes 0 or not.

If the remainder is 0, it was received normally,
That is, since it is determined that the error has not occurred, the error-free display ACK is returned from the reception side to the transmission side, and the transmission side returns the error-free display ACK.
Is received and the line is restored. In the above embodiment, the error detection additional code C is obtained by the CRC method, but the present invention is not limited to this, and for example, the following BCC (BLOCKCHECK CHARACTER) method may be adopted. .

A method of obtaining the error detection additional code C by the BCC method will be described. Consider a telex call.
Let S be a character string of a message transmitted from the transmitting terminal. The received message when the receiving terminal receives S is a character string R. However, s _i = 1 or 0 and r _i = 1 or 0 (i = 1 to n). S = (s ₁ , s ₂ ... s _n ) R = (r ₁ , r ₂ ... r _n )

In a normal call with no garbled characters, the following equation holds. S = R (5) In an abnormal call with garbled characters, the following equation holds. S ≠ R (6)

Here, the function F (X) is introduced. Variable x
Is an arbitrary character string. The function F has a general value Y. Y = F (X) (7) It is self-evident that the following expression holds in a call without garbled characters. F (S) = F (R) (8)

What kind of relationship will be established in a garbled call? The function F may have the same value even if different variable values are substituted. Therefore, the relationship shown in the following equation may be established. S ≠ R and F (S) = F (R) (9) At this time, an error cannot be recognized. As the function F, a function for which the expression (9) does not hold should be selected as much as possible.

Here, the function F is properly selected, and the function that does not hold the equation (9) with high probability is H. This way
With a high probability, the following equation holds. Therefore, when S ≠ R, H (S) ≠ H (R) (10) Therefore, Y = H (S) is calculated on the transmitting side, and the character string C in which Y is expressed in telex characters next to the telex message is calculated. Add and send to the receiving side. On the other hand, the receiving side calculates Z = H (R), compares the calculated Z with the received C, and determines that the characters are garbled when they do not match, that is, when the following equation is satisfied. Z ≠ C (11)

As described above, in the BCC method, the function H is a function for checking the parity of the transmission character string S, and the character string C having the same value as Y is a block parity check character (BCC character). That is, the BCC character is used as the error detecting additional code of the present invention.

[0053]

As described above in detail based on the embodiments, according to the error character retransmission protocol of the present invention,
It has the following effects. The receiving side can automatically detect the presence or absence of an error. It is possible to automatically notify the sender that an error exists on the receiver while the line is held. When there is an error on the receiving side, the same telegram can be automatically retransmitted as a response with the line held, or only the portion including the error (for example, the line including the error) can be automatically retransmitted. There is no need to add functions to the public telex network. Normal communication is possible between a sender terminal equipped with the protocol of the present invention and a receiver terminal not equipped with the protocol of the present invention. In the terminal equipped with the protocol of the present invention, it is not necessary to change the parameter settings for masking the protocol of the present invention.

[Brief description of drawings]

FIG. 1 is a flowchart showing an error character retransmission protocol for telex communication according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a fifth embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a sixth embodiment of the present invention.

FIG. 8 is a configuration diagram of an international telex 5-unit code.

FIG. 9 is an explanatory diagram showing a correspondence between a 5-unit code and a character.

[Explanation of symbols]

REQ00 Error character retransmission protocol start instruction (1 time full text retransmission) REQ10 Error character retransmission protocol start instruction (N times full text retransmission) REQ01 Error character retransmission protocol start instruction (1 time 1 time)
Line resend REQ11 Error character resend protocol start instruction (N times 1
Line re-transmission) REP Re-transmission display ACK No error notification NAK Error notification C Error detection additional code (including identification header)

Claims (7)

[Claims] 1. A transmission side terminal adds an error detection additional code to a character string of a telegram to be transmitted and transmits it to a reception side terminal,
An error character detection method for telex communication, wherein the receiving side terminal determines whether or not the error detection additional code is normal. 2. A character string of a telegram to be transmitted is divided line by line from a transmitting side terminal, an error detection additional code is added to each line, and the error is transmitted to the receiving side terminal. An error character detection method for telex communication characterized by determining whether or not a detected additional code is normal. 3. When the receiving side terminal determines that the error detecting additional code is not normally received, it returns a notification of an error to the transmitting side terminal. Or the error character detection method for telex communication according to 2. 4. The error character for telex communication according to claim 3, wherein when the sending side terminal receives a notification of an error from the receiving side terminal, the character string of a telegram to be sent is sent again. Detection method. 5. The error-free notification is returned to the transmission-side terminal when the reception-side terminal determines that the error detection additional code is normally received. Or the error character detection method for telex communication according to 2. 6. The error character detection method for telex communication according to claim 1, wherein a check sequence in a CRC method is converted into a character string and used as the error detection additional code. 7. The value obtained by a parity check function according to the BCC method is converted into a character string and used as the error detection additional code.
Error character detection method for telex communication described.