JP2002118502A - Message processing method and digital data receiver in digital data communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a message processing method in which, when received messages are overlapped, the message having a smaller error character can be output and which can save the capacity of a memory storing the messages. SOLUTION: When a newly received message 30 and an existing message M2 are indentical messages, the error rate n3 of the received message 30 is compared with the error rate n2 of the existing message M2. When the error rate n3 of the received message 30 is lower than the error rate n2 of the existing message M2, the existing message M2 is discarded and the received message 30 is stored newly. When the error rate n2 of the existing message M2 is lower than the error rate n3 of the received message 30, the existing message M2 is kept as it is, and the received message is discarded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a message processing method and a digital data receiver in digital data communication such as vigation telex).

[0002]

2. Description of the Related Art NAVEX is a system in which a base station transmits a navigation alert, weather information, and the like as character data on a regular basis to a traveling ship. NAVEX has
There are international NAVEX and Japanese NAVTEX. In international NAVEX, the ITU standard (Rec.ITU-R
According to M625 TABLE1), one character is composed of 7-bit data. In addition, Japanese NAVTE
In X, the ITU standard (Rec. ITU-R M493 T
According to ABLE1), the code configuration of one character is 10 bits, the upper 7 bits are assigned a character code up to the second level of the kanji code of JIS X0208, and the lower 3 bits.
An error correction code is assigned to the bit. Then, by combining the characters composed of these digital data, a message of various information to be transmitted to the ship is configured.

[0003] In such a NAVTEXT system, a plurality of base stations are provided, but the transmission frequency is uniformly 518K.
Hz, the message is transmitted at a different time to avoid interference when transmitting the same message from each base station. For this reason, which base station performs transmission in which time zone is assigned in advance. For example, there is a 10-minute time interval between the transmission of one base station and the transmission of the next base station. Each message contains an I
A D number is given, and according to the standard, the received message is stored for 60 hours or more, and is deleted before 72 hours. If a message having the same ID number as the previous message is received during this time, the message is treated as the same message as the previous message, and after 72 hours or more, the message having the same ID number as the previous message is processed. If received, the message is treated differently. Therefore, a ship may receive the same message a plurality of times in less than 72 hours.

Incidentally, a message transmitted from a base station is received by a NAVEX receiver mounted on a ship and printed out. Regarding the printing of a message, the error rate of a previously received message is 4 according to the standard.
% Or more, the same message received later is reprinted. If the error rate of the message received in the past is less than 4%, the ID number of the received message is saved and The received message having the same ID number is not reprinted.

[0005]

SUMMARY OF THE INVENTION The above-described NVT
EX receivers usually have a printer,
Storing the message in memory is not essential since the received message can be printed out and left on paper. However, depending on the receiver, L
Some display devices, such as CDs (Liquid Crystal Displays), are provided and messages are displayed on the screen. In such a receiver, if the display disappears, the message disappears. Therefore, in order to leave the message, it is necessary to provide a memory and store the message.

In this case, if all the received messages are stored in a memory (RAM), they can be displayed again when necessary. However, only by such a method, when a message having a small number of error characters and a message having a large number of error characters coexist, it is difficult to know which message has a small number of error characters without actually displaying the message. In addition, although only the one with a smaller number of error characters should be stored, both of them are stored, so that there is a problem that the memory capacity increases.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. When received messages are duplicated, a message with less error characters can be output and the message is saved. The task is to save memory capacity.

[0008]

In order to solve the above problems, according to the present invention, when a new message is received,
The error rate of the received message is compared with the error rate of an existing message having the same content received and stored earlier. If the error rate of the received message is lower than the error rate of the existing message, the existing message is discarded and the received message is newly stored. on the other hand,
If the error rate of the existing message is lower than the error rate of the received message, the received message is discarded.

In this way, when there is a duplicate message, the one with a small number of error characters is automatically selected and the one with a large number of error characters is discarded. Can be output. Also, since only the message with the smaller number of error characters is stored in the memory, the memory capacity can be saved, and if the memory capacity is the same, the number of messages to be stored can be increased.

Here, in order to determine whether or not a plurality of messages have the same content, the message ID of the received message matches the message ID of the existing message, and the time difference between the messages is less than a predetermined time. In this case, the received message may be regarded as a message having the same content as the existing message.

Further, even when the error rate of the existing message is higher than that of the received message, if the error rate is less than a certain value, it is preferable to treat the error rate of the existing message as 0%. This is because if the error rate is very small (less than 4% in the international NAVTEXT standard), the message content can be decoded in most cases, and it is not necessary to replace it with a new message.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is a block diagram of a NAVTEX receiver that is an example of a digital data receiver. In the figure, 1 is a receiving unit for receiving a NAVTEXT message transmitted from a base station (not shown), 2 is a processing unit for analyzing data received by the receiving unit 1 and reproducing the message, and 3 is a processing unit for reproducing the message. A display unit 4 for displaying the displayed message, a printing unit 4 for printing out the message reproduced in the processing unit 2, and an operation unit 5 for performing display, printing, and the like. The display unit 3 is incorporated in the main body of the receiver, but the printing unit 4 is not incorporated in the main body of the receiver, and is externally attached as needed.
The display unit 3 and the printing unit 4 constitute an output unit of the present invention.

The receiving section 1 has N
A receiving antenna 1a for receiving an AVTEX message is provided. The processing unit 2 includes a microcomputer including a CPU, memories (ROM and RAM), input / output ports, and the like. The display unit 3 is configured by a liquid crystal display or the like, and the printing unit 4 is configured by a thermal printer or the like. The operation unit 5 includes various keys and display lamps.

FIG. 2 shows an example of a message of maritime safety information displayed on the display unit 3 in the international NAVEX receiver. "ZCZC" at the beginning is a broadcast start code,
“G” indicates a broadcast station (base station) classification, “A” indicates a message type, and “13” indicates a message serial number. The message ID is configured by “GA13”. “NNNN” at the end is a code indicating the end of the message. On a Japanese NAVEX receiver, the message is represented in Japanese.

FIG. 3 is a diagram for explaining the outline of message processing in the processing section 2. In the figure, 10 is a character string storage area for storing a character string constituting a message, 20 is a message information storage block for storing information on each message, and 30 is a new received message newly received by the receiver. It is.

The character string storage area 10 and the message information storage block 20 are stored in a memory (RA
M). Character string storage area 10
Has addresses of “0” to “m”, and each address stores one character (7 bits in the case of international NAVEX). In the example of the figure, addresses “0” to “i”
One message M1 is composed of character strings up to "-1", and another message M2 is composed of character strings of addresses "i" to "j-1". The same applies to addresses "j" and below. . Each message M1, M2, ...
Starts from ZCZC and NNN as shown in FIG.
Consists of a character string ending with N.

The message information storage block 20 stores the messages M1, M stored in the character string storage area 10.
An area in which information (a type of management information) relating to 2,... Is recorded, where m1 is message information relating to the message M1, and m2 is message information relating to the message M2. The same applies to the following messages. Each message information m1, m2,... Includes an area use flag, a message start position, a message end position, a message ID, a message storage time, and a message error rate. These will be described below.

The area use flag is a flag indicating whether the area of the character string storage area 10 corresponding to the message is in use or not. If the area is in use, it is set to "1". Reset to "0". For example,
Since the message M1 is contained in addresses "0" to "i-1" of the character string storage area 10 and is in use, the area use flag in the message information m1 is "1". The same applies to the message information m2.

The message start position is in the character string storage area 1
0 indicates the start address of each message stored in the message M1. Since the message M1 is stored from the address "0", the message start position is "0" and the message M2 is
Is stored from the address “i”, the message start position is “i”.

The message end position is in the character string storage area 1
0 indicates the end address of each message stored in the message 0. Since the message M1 ends at the address "i-1", the message end position is "i-1", and the message M2 is the address "j-1". , The message end position is “j−1”.

The message ID is an identification number assigned to each message, and includes a broadcast station classification, a message type, and a serial number as described with reference to FIG. The message ID of the message M1 is “GE33”,
The message ID of the message M2 is “GA13”, and the IDs of the two are different.

Message storage time tx (x = 1, 2,
..) Represents the time at which the received message was stored in the memory. This time is recorded based on a clock signal generated from a clock circuit built in the processing unit 2.

The message error rate nx (x = 1, 2, 2)
..) Represents the ratio of error characters in all characters constituting the message. If there are five error characters out of 100 characters, the error rate is 5%. Error characters are indicated by symbols such as “*”.

The newly received message 30 is a message that has been received by the receiving unit 1 and temporarily stored in a buffer inside the processing unit 2. Reference numeral 31 denotes message information relating to the message 30, and includes a message ID, a message storage time, and a message error rate. The message ID and the message error rate are the same as those described above. The message save time represents the current time in this case.

Next, a message processing procedure will be described. When a new reception message (hereinafter, referred to as a reception message) 30 is received by the reception unit 1, the processing unit 2 transmits the message information 31 relating to the reception message 30 and a message previously received and stored (hereinafter, existing message). ., M1, M2,...

As a result of the comparison, if all of the following conditions a to c are satisfied, the received message is handled as the same message as the existing message. a. The area use flag for the existing message is “1” b. Message ID of received message and existing message
Are the same c. t-tx <72h (the time difference between the received message and the existing message is less than a certain time)

That is, as for a, if the area use flag is "0", the received message is another message because the existing message is not a valid message and has already been discarded. As for b, if the message IDs are not the same, the received message and the existing message are naturally different messages. Further, as for c, if the received message has passed 72 hours or more than the existing message, the received message and the existing message are treated as different from each other in the standard as described above.

As described above, the processing unit 2 performs the following processing on each message information in the message information storage block 20.
The conditions a to c are sequentially checked to determine whether the received message is the same as the existing message. This is the determination in the first stage. For example, when the received message 30 is compared with the existing message M2, the area use flag of the existing message M2 is "1" and both message IDs are "GA13".
If tt2 <72h, it is determined that the received message 30 is the same message as the existing message M2.

Next, when the received message is the same as the existing message, the processing unit 2 determines whether or not the existing message should be replaced with the received message.
This is the determination in the second stage. This determination is made based on the result of comparison between the error rate of the received message and the error rate of the existing message.

FIG. 4 shows the error rate n of the received message 30.
3 is an existing message M2 determined to be the same message
Is lower than the error rate n2 (n2> n3). In this case, a process of discarding the existing message M2 and newly storing the received message 30 is performed. That is, in the message information m2 of the message information storage block 20, the area use flag is reset to “0”, and the storage area (addresses “i” to “j−1”) of the existing message M2 in the character string storage area 10 is invalid. Becomes used (empty) and the existing message M2
Becomes invalid. On the other hand, the received message 30 is stored as a message Mx at the addresses “k” to “l−1” of the character string storage area 10, and the message information 31 includes the message information 31 mx as message information storage block 2
0 is stored in a predetermined area. By the above processing, the existing message M2 becomes the same as the received message 30 (M
x).

FIG. 5 shows the error rate n of the existing message M2.
2 indicates a process when the error rate n3 of the received message 30 is lower (n2 <n3). In this case, the received message 3
A process of discarding 0 is performed. That is, the message information m2 in the message information storage block 20 is unchanged, and the received message 30 is discarded as invalid. As a result, the existing message M2 remains valid without being replaced by the received message 30.

As described above, when the messages are determined to be the same, the respective error rates are compared, the message with the higher error rate is discarded, and the message with the lower error rate is stored or maintained. become. In addition,
If the value of the error rate of the existing message is very small (for example, less than 4%), the error rate is determined to be 0%.
This will be described later.

If any of the message information recorded in the message information storage block 20 does not satisfy the above conditions a to c, the processing unit 2 newly stores the received message 30. FIG.
Shows processing when the time difference between the received message 30 and the existing message M2 is 72 hours or more.

In FIG. 6, the area use flag of the existing message M2 is "1", and the message ID (GA13) of the received message 30 and the existing message M2 also match. However, since t-t2≥72h, it follows the standard. , The received message 30 is regarded as a different message from the existing message M2, and the received message 30 is newly stored. That is, the received message 30 is stored as a message My at addresses “k” to “l−1” in the character string storage area 10, and the message information 31 is stored in the message information 31 together with information on the area use flag and the message start / end position. my is stored in a predetermined area of the message information storage block 20. On the other hand, unlike the case of FIG. 4, the existing message M2 is maintained as it is.

FIG. 7 is a flowchart showing the above-described message processing method, and shows a procedure executed by the CPU of the processing unit 2. When the receiving unit 1 receives a received message, the processing unit 2 compares each message information of the received message and each message information of the existing message one by one (step S1), and determines whether the existing message M1 is valid (step S2). ). In the example of FIG. 4, since the area use flag of the existing message M1 is "1", the message M1 is valid, and the determination in step S2 is Y.
ES.

Next, it is determined whether or not the message ID of the received message 30 matches the message ID of the existing message M1 (step S3). Message I of received message 30
Since D is “GA13” and the message ID of the existing message M1 is “GE33”, the two do not match,
The determination in step S3 is NO, and step S11
Move to In step S11, it is determined whether the received message has been compared with all existing messages. However, since the comparison with all existing messages has not been completed, the determination is NO, and the process returns to step S1 to return to the next existing message. Compare with M2.

Since the area use flag of the existing message M2 is "1", the determination in step S2 is YES, and it is next determined whether or not the message IDs match (step S3). Since the message IDs of the received message 30 and the existing message M1 are both "GA13" and they match, the determination in step S2 is YES. Then, is the time difference between the received message 30 and the existing message M2 less than 72 hours? Is determined (step S
4).

In the example of FIG. 4, since t-t2 <72h, the determination in step S4 is YES, and at this time, the received message 30 is regarded as a message having the same content as the existing message M2. Therefore, the error rate is compared to discard any of the messages, but prior to that, the error rate of the existing message is 4%.
It is determined whether it is less than (Step S5). If the error rate is not less than 4%, the process directly proceeds to step S7. If the error rate is less than 4%, the error rate is set to 0% (step S6), and the process proceeds to step S7.

Next, the error rate of the received message is compared with the error rate of the existing message (step S7).
When the error rate n3 of the received message 30 is lower than the error rate n2 of the existing message M2 (in the case of FIG. 4),
The existing message M2 is discarded (step S8), and the received message 30 is newly stored (step S9). On the other hand, when the error rate n2 of the existing message M2 is lower than the error rate n3 of the received message 30 (case of FIG. 5).
Discards the received message 30 while keeping the existing message M2 as it is (step S10). Also, if the error rate of the received message is equal to the error rate of the existing message,
Since there is no need to replace the message, the received message is discarded (step S10).

Here, the error rate n of the existing message M2
2 is 3%, for example, and the error rate n of the received message 30
If 3 is 2%, for example, the determination in step S7 should be YES, and the message should be replaced in steps S8 and S9.
In step 6, since the error rate n2 of the existing message M2 is forcibly set to 0%, the determination in step S7 is NO, and the message is not replaced. This is based on the following reasons.

That is, if the error rate is about 3%,
The number of error characters (indicated by *) in the message is small, and in most cases the message can be decrypted. Therefore, there is little need to discard existing messages and replace them with new messages.
Further, when the user has already viewed the existing message, outputting the same message again increases the complexity. However, the processing in steps S5 and S6 is a preferable example, but is not essential in the present invention, and may be omitted. Also, regarding the numerical value of 4% in step S5, the NAV
The value is restricted to 4% when complying with the TEX standard. In other cases, a value other than 4% may be adopted.

In the case of FIG. 6, the determination in step S4 is NO, and the process proceeds to step S11 to determine whether the comparison with all existing messages has been completed. If the comparison is not completed, the process returns to step S1,
Compare with the next existing message. If all of steps S2 to S4 are YES (if the messages are the same), step S5 and subsequent steps are executed. on the other hand,
If any of steps S2 to S4 is NO,
The process returns to step S11 to determine whether the comparison with all the existing messages has been completed. If not, the process returns to step S1 to compare with the next existing message. In the same manner, the comparison with the existing message is repeated until all the steps S2 to S4 become YES (until the same message is found). Then, if the same message is not found when the comparison with all the existing messages is completed, the process proceeds from step S11 to step S9, and the received message 30 is stored as a new message (My in FIG. 6).

FIGS. 8 to 10 show message list screens displayed on the display unit 3. FIG. FIG. 8 shows a state before receiving a new received message, in which only a list of existing messages is displayed. 40 is the message ID of the existing message. 41 indicates the type of message, and "!!" indicates that the message is an alarm. Reference numeral 42 indicates whether or not browsing is performed.
"W" indicates that the message has not been viewed (including the message after replacement). In the message ID 40, “GA13” is the message M
2, "GE33" corresponds to the message M1.

FIG. 9 shows a case where a new received message is received, and shows a state where the received message is newly stored in addition to the existing message as in the processing in FIG. Here, two messages whose message IDs are “GA13” are displayed.
Reference numeral 4 denotes an existing message (M2 in FIG. 6), and message 43 is a message (My in FIG. 6) newly saved as a different message from the message 44.

FIG. 10 shows a case where a new received message is received, and shows a state in which an existing message is replaced with a received message as in the processing in FIG. Here, the newly saved message 43 (Mx in FIG. 4)
Only displayed and discarded message (M2 in FIG. 4)
Is not displayed.

As shown in FIG. 5, when the received message is discarded, the discarded message is not displayed. Therefore, in the case of FIG. 5, the screen of the display unit 3 remains unchanged in FIG.

When a required message is selected by operating the operation unit 5 while viewing the list of messages displayed on the display unit 3 as described above, the screen is switched and the contents of the message are displayed as shown in FIG. . In addition, since the message is stored in the memory, the contents of the message required at any time can be displayed on the display unit 3, and the message can be left without the printing unit 4. When the printing unit 4 is connected, a message can be printed out in addition to the display. Here, if the same message is received at a time interval before the elapse of 72 hours or more, the message with the lower error rate is automatically left, and the message with the higher error rate is discarded. Therefore, the content can always be clearly understood with a message having few error characters. Also, if you read an earlier message before you receive a later message,
Even if there are many error characters and it is difficult to read, if the subsequent message has few error characters, it can be output again, so that the message content can be confirmed.

Furthermore, when the same message is duplicated, only the message having a low error rate is stored without storing both, so that the memory capacity can be saved. If the memory capacity is the same, more messages can be stored.

In the above embodiment, NAVTEX
Although the receiver has been described as an example, the present invention is not limited to this. The present invention can be applied to all systems that receive messages having the same content at time intervals, for example, NBDP (Narrow Banner).
It can also be applied to marine communication systems such as d Direct Printing (narrow band direct printing telegraph device).

The present invention, in which received messages are stored, is particularly useful in a receiver provided with a display unit instead of a printing unit, but is also applicable to a receiver provided with only a printing unit without a display unit. Can be applied. In this case, it is possible to eliminate waste of paper caused by printing duplicate messages.

[0051]

According to the present invention, a message having a low error rate is stored and a message having a high error rate is discarded, thereby outputting a clear message with few error characters. In addition to this, unnecessary messages are not left, so that memory capacity can be saved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a NAVEX receiver.

FIG. 2 is a diagram illustrating an example of a message.

FIG. 3 is a diagram illustrating an outline of message processing.

FIG. 4 is a diagram illustrating a process of discarding an existing message.

FIG. 5 is a diagram illustrating a process of discarding a received message.

FIG. 6 is a diagram illustrating processing when messages are different.

FIG. 7 is a flowchart of a message processing method.

FIG. 8 is a diagram showing a message list screen.

FIG. 9 is a diagram showing a message list screen.

FIG. 10 is a diagram showing a message list screen.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiving part 2 Processing part 3 Display part 4 Printing part 5 Operation part 10 Character string storage area 20 Message information storage block 30 Newly received message 31 Message information M1, M2 ... Existing message m1, m2 ... Message information

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04L 12/54 H04L 11/20 101Z 12/58 F term (Reference) 5K021 AA08 BB04 CC03 CC14 DD01 EE04 GG03 5K030 GA06 HA05 HC03 JL01 KA02 LC18 LD18 5K033 AA04 BA06 DA01 DA17 DB12 5K061 BB17 DD00 FF03 FF06 JJ07

Claims (5)

[Claims] In a system for receiving a message of the same content composed of digital data at a time interval, when a new message is received, an error rate of the received message, and an error rate of the received message, which is received and stored earlier. If the error rate of the received message is lower than the error rate of the existing message, the existing message is discarded and the received message is newly saved. A message processing method in digital data communication, wherein the received message is discarded when the error rate is lower than the error rate of the received message. 2. A receiving unit for receiving a message of the same content composed of digital data at a time interval, when a new message is received, an error rate of the received message, and receiving and storing earlier than this. If the error rate of the received message is lower than the error rate of the existing message, the existing message with the same content is compared with the existing message. When the error rate of the message is lower than the error rate of the received message, the processing unit performs a process of discarding the received message, and an output unit that outputs the message processed by the processing unit. Digital data receiver. 3. The processing unit according to claim 1, wherein the message ID of the received message matches the message ID of the existing message.
The digital data receiver according to claim 2, wherein the received message is regarded as a message having the same content as the existing message when the time difference between the messages is less than a predetermined time. 4. The processing unit according to claim 1, wherein the error rate of the existing message is set to 0 when the error rate of the existing message is less than a predetermined value.
The digital data receiver according to claim 2 or 3, which is treated as%. 5. The digital data receiver according to claim 2, wherein said message comprises NAVEX data.