JPS63136854A - Monitor system for detecting and deciding synchronous word - Google Patents

Abstract

PURPOSE:To reduce the trying again of a synchronous return action due to error detection by collating respective bit patterns of a detection synchronous word and a detection specific code word with a reception signal in a bit unit and preventing back up if both the synchronous word and the specific code word cannot be detected. CONSTITUTION:A counter is stepped and a detected number is counted whenever synchronous word detection information B-13 is inputted in a continuous period. With office identification code detection information A-41 (which is outputted only when an office identification code is not detected) outputted from an office identification code detection circuit A-4, the counter of a synchronous word detection protection circuit A-3 is reset. Namely, only when the synchronous word detection circuit shows the detection of the synchronous word, and the office identification code detection circuit A-4 shows the detection of an office identification code, the detected number is counted. Thus, the synchronous return action due to error detection can be prevented from being tried again and synchronous pull-in from being taken time.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a digital communication system that detects a synchronization word from a received signal that is received and demodulated at a constant cycle, and then reconfirms and monitors the detection of the synchronization word. This invention relates to a method for monitoring the detection of synchronization words in a system.

(Prior Art) As is well known, in a digital communication system, a synchronization word is detected from a received signal that is received at regular intervals, and a time reference for starting transmission of data, etc. is determined. However, when detecting this synchronization word, there are cases where the synchronization word in the received signal is the correct synchronization word but cannot be detected due to deterioration of line quality or thermal noise, etc. There is a problem in that there is a bit error in a part other than the synchronization word in the signal, and that the erroneous bit pattern is mistakenly detected as the correct pip 1 pattern of the synchronization word.

Therefore, in order to prevent such non-detection and false detection, in the synchronization recovery process, there is a backward protection in which a synchronization word is not considered detected unless several synchronization words are detected in an arbitrary period, and a backward protection is implemented after the backward protection is satisfied. In the synchronization maintenance process, there are cases where detection is not possible due to non-detection, etc., so when several synchronization words are detected in an arbitrary period, it is assumed that the synchronization word cannot be detected and the process returns to the synchronization recovery process of backward protection. It uses a medical tale. In other words, the synchronization word is detected from the received signal (backward protection), and the detection of the synchronization word is monitored (forward protection).

Next, a conventional synchronization word detection and monitoring method will be specifically explained with reference to FIG.

The conventional synchronization word detection and monitoring system basically includes a synchronization word detection circuit B-1, a synchronization word allowable error number setting circuit B-2,
and a synchronization word detection protection circuit B-3.

First, the backward protection operation during the synchronization 1N and return process is performed as follows.

In the synchronization word detection circuit B-1 to which the demodulated received signal B-11 is input, a detection synchronization word having the same bit pattern as the synchronization word in the received signal B-11 is set in advance. In addition, in the synchronization word allowable error number setting circuit B2, when receiving and demodulating the reception signal B-11 from the transmission path, the synchronization word in the reception signal B-11 is Since the bit pattern may change and not be input to the synchronization word detection circuit B-1 as an accurate synchronization word, the allowable range of errors in the bit pattern of the synchronization word (tolerable number of errors)
is set in advance, and its synchronization word allowable error number setting information B
-21 is input to the synchronization word detection circuit B-1.

Therefore, in the synchronization word detection circuit B-1, first, the received signal B-
11 bits are compared with the synchronization word for detection, and the mismatched bits 1 to 1 are checked.
It is determined one by one whether the number is within the tolerance range indicated by the synchronization word allowable error number setting information B-21, and if a bit pattern position where the number of mismatched bits is within the tolerance range can be detected, the synchronization word detection information B -13 is set to "synchronization word detection" and sent to the synchronization word detection protection circuit B-3.

Next, in the synchronization word detection circuit B-1, the same operation 1t as described above is repeated at the detected bit pattern position of the received signal B-11 from next time onwards.7 At this time, the "synchronization word detection J When the synchronization word detection and protection circuit B-3 is executed, the synchronization word detection protection information B-31 whose content is that the backward protection operation f is completed is input, so the data+i11 report is input from the synchronization word detection circuit B-1. Tearo received signal B-12
is output, and the process shifts to the forward gA tan operation, which will be described later.

In addition, if "synchronization word non-detection" exists even once, synchronization word tolerance error 81 information B-31 is input from the synchronization word detection protection circuit B-3, which includes redoing the synchronization recovery operation. The word detection circuit B-1 restarts its synchronization word detection operation from the first step.

In the synchronization word detection protection circuit B-3, when the synchronization word detection information B-13 whose content is "synchronization word detection" is input, the counter is reset by 3, and if it is input continuously thereafter, it counts up one by one. The number of detections is counted, and when the counted value satisfies a predetermined condition, synchronized word detection protection information B-31 containing the end of the backward medical story operation is outputted. Furthermore, when the synchronization word detection information B-13 whose content is "synchronization word not detected" is input after setting the counter to cell 1, the counter is reset... Synchronous word detection (scenario information B-31) as the content is output.

Next, the forward (l) operation in the synchronization maintenance process is performed as follows.

When the synchronization word detection circuit B-1 cannot detect the synchronization word, the synchronization word detection circuit B-1 generates synchronization word detection information B-13 indicating that the synchronization word is not detected.
is sent to the synchronization word detection protection circuit B-3. In the synchronization word detection protection circuit B-3, a counter is set by the input of "synchronization word non-detection", and when it is input continuously, it is counted up one by one to count the number of non-detection times, and the count value is When a predetermined value is satisfied, the synchronization word detection protection information B-31 is sent to the synchronization word detection circuit B-1, and the synchronization word detection protection information B-32 is sent out, for example, to the outside.

Synchronous word detection circuit B- for synchronized word detection protection information B-31
In case 1, automatic transition to rear protection operation or operation stop is taken. Further, the synchronization word detection protection information B-32 is used, for example, as a caution signal for warnings, etc., and the system is temporarily stopped, after which the synchronization recovery operation is restarted.

Note that the counter is reset if "synchronization word detection" is performed at least once before the "synchronization word non-detection" does not occur consecutively and the number of synchronization non-detection times reaches a predetermined value.

(Problems to be Solved by the Invention) However, the conventional synchronization word detection and confirmation method described above has the following problems.

First, in the so-called backward cA operation, a method is used to determine whether or not the synchronization word can be detected in the same way from the next cycle onward at the position where the synchronization word was detected in the previous cycle. If there is an erroneous detection that is determined to be a word, from now on, the synchronous word tolerance error will be performed at the position where the erroneous detection occurred, but since it is an erroneous detection, the erroneous detection will be performed at the same position in the next cycle as well. Therefore, the counter is reset and the synchronization recovery operation has to be repeated.In other words, it takes time to pull in the synchronization.

In addition, in forward protection movement (at t, if a non-detection that is missed despite the correct synchronization word occurs due to deterioration of the lip quality, etc., this non-detection will continue, so the synchronization word can be detected at the correct position. Although the synchronization state is still in effect, it is necessary to issue synchronization word detection protection information to redo the synchronization return operation, which makes it impossible to receive necessary data information.In other words, it becomes extremely difficult to maintain synchronization. .

The present invention was developed in view of these problems, and its purpose is to speed up the detection of a synchronization word included in a received signal, as well as to monitor and prevent non-detection and false detection, thereby confirming synchronization pull-in. An object of the present invention is to provide a detection and confirmation monitoring method for a synchronization word, which can perform synchronization and shorten the synchronization pull-in time.

(Means for Solving the Problems) In order to achieve the above object, the synchronization word detection and confirmation monitoring system of the present invention has the following configuration.

That is, the synchronization word detection and confirmation monitoring method of the present invention detects a synchronization word from a received signal that is received and demodulated at a fixed period, and then confirms the detection of the synchronization word again for monitoring. In the detection confirmation monitoring method, a detection synchronization word having the same bit pattern as the synchronization word included in the received signal is set in advance, and a bit-by-bit comparison between the detection synchronization word and the received signal is performed. and a synchronization word detection means for outputting synchronization word detection information indicating whether or not the number of mismatched bits is within a range of a synchronization word allowable error number; included in the received signal and different from the synchronization word. A specific code word for detection having the same bit pattern as a specific code word consisting of a PIP pattern is set in advance, and the specific code word for detection and the received signal are compared bit by bit, and the number of mismatched bits is determined. a specific code word detection means for outputting specific code word detection information indicating whether or not the code word is within a range of allowable error numbers; in a synchronization recovery process, the synchronization word detection information indicates detection of a synchronization word, and the specific code The number of detections is counted only when the word detection information indicates specific code word detection, and when the counted value satisfies a predetermined value, first synchronization word detection protection is applied to the synchronization word detection means and the specific code word detection means. a backward protection control means for outputting information; only when the synchronization word detection information indicates non-detection of a synchronization word and the specific code word detection information indicates non-detection of a specific code word in the synchronization maintenance process; forward protection control means for counting the number of synchronization words and outputting second synchronization word detection protection information to the synchronization word detection means and the specific code word detection means when the counted value satisfies a predetermined value; This is a detection and confirmation monitoring method for synchronization words.

(Operation) Next, the operation of the synchronization word detection confirmation monitoring method of the present invention having the above-mentioned configuration will be explained.

The synchronization word detection means performs a bit-by-bit comparison between a preset detection synchronization word and the received signal, and generates synchronization word detection information indicating whether the number of mismatching bits is within the range of the synchronization word allowable number of errors. It outputs to the rear protection control means and the front protection control means. Further, the specific code word detection means performs a bit-by-bit comparison between a preset specific code word for detection and the received signal, and determines whether the number of mismatching bits is within the range of the specific code word allowable number of errors. The specific code word detection information shown is output to the backward protection means and the forward protection means.

Note that the number of synchronization word allowable errors and the number of specific code word allowable errors are determined by the number of errors due to poor line quality when receiving and demodulating the received signal from the transmission path.
In consideration of the fact that the bit pattern of the synchronization word or specific code word in the received signal may change due to the influence of heat or thermal noise, the number indicates the permissible range of error in these patterns. , that is, it is set in advance as the number of allowable errors.

Furthermore, if the transmission frame is divided into a control information part that includes the synchronization word and a data information part that follows this control information part, the specific code word can be any code that is included in the control information part and is different from the synchronization word. A code Hfi, which is a word (either an existing one or a newly created one) and preferably has correlation properties, is selectively used.

In the synchronization recovery process, the backward protection control means counts the number of detections only when the synchronization word detection information indicates detection of a synchronization word and the specific code word detection information indicates detection of a specific code word, and calculates a count value. When satisfies a predetermined value, first synchronization word detection protection information is output to the synchronization word detection means and the iη specific code word detection means. As a result, the synchronization word detection means and the specific code word detection means shift to forward protection operation, which will be described later.

Next, in the synchronization maintenance process, the forward protection control means controls the number of non-detections only when the synchronization word detection information indicates non-detection of a synchronization word and the specific code word detection information indicates non-detection of a specific code word. and outputs second synchronization word detection protection information to the synchronization word detection means and the specific code word detection means when the counted value satisfies a predetermined value.

As a result, the synchronization word detecting means and the specific code word detecting means shift to one step or stop the operation of the backward protection. As described above, according to the synchronization word detection confirmation monitoring method of the present invention, a detection specific code word is set in addition to the detection synchronization word, and when detecting the synchronization word from the received signal, the detection synchronization word and the detection specific code word are set. Each bit pattern of the specific code word for detection is compared bit by bit with the received signal, and in the synchronization recovery process, normal backward protection is not entered unless both the synchronization word and the specific code word can be detected. It is less likely that the synchronization return operation will have to be repeated due to erroneous detection, and as a result, it will take less time to pull in the synchronization, and it will also be possible to monitor the confirmation of the synchronization word detection more reliably.

In addition, in the synchronization maintenance process, the normal forward 11 Lit is entered only when both the synchronization word and the specific code word are not detected, which has the effect of keeping the probability of synchronization loss due to non-detection etc. low. There is, and also,
This serves as a reconfirmation monitoring of synchronization word detection, which has an important effect in maintaining synchronization. Furthermore, according to the present invention,
This has the effect of allowing both front and rear protection methods to be used as is.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
The figure shows the overall configuration of a synchronization word detection confirmation monitoring system according to an embodiment of the present invention.

The synchronization word detection confirmation monitoring method of one system in this embodiment includes a synchronization word detection circuit B-1, a synchronization word permissible error number setting circuit B-2, and functions as a backward protection control means and a forward protection control means. A synchronization word detection protection circuit A-3, a station identification code detection circuit A-4 that detects a station identification code as a specific code word, and a station identification code allowable error number setting circuit A-5 are basically constructed in one circuit. .

Synchronization word detection circuit B-1 and synchronization word allowable error number setting circuit B-
2 has already been explained, so a re-explanation will be omitted.

The number of allowable errors set in the station identification code allowable error number setting circuit A-5 is determined in the same way as the setting in the synchronization word allowable error number setting circuit B-2, and the number of allowable errors in the station identification code is set in the setting circuit A-5. -51 is station identification code detection circuit A-4
given to.

The station identification code detection circuit A-4 selects a station identification code as an arbitrary specific code word different from the synchronization word in the control information part where the synchronization word exists in the transmission frame, and selects the same bit as this station identification code. A station identification code for detection consisting of a pattern is set in advance. This station identification code detection circuit A-
4, the received signal B-11 is inputted via the synchronization word detection circuit B-1 or in parallel with the synchronization word detection circuit B-1. In this embodiment, as shown in FIG. -1
Therefore, the received signal B-12, which is data information output in the synchronization maintenance process, is sent out from this station identification code detection circuit A-4. Furthermore, the operation of the station identification code detection circuit A-4 is performed in exactly the same way as the synchronization word detection circuit B-1, except that the detection target is different, so the explanation thereof will be omitted. In this embodiment, the identification code detection information A-41 is output when "not detected" in the synchronization recovery process and when "r detected" in the synchronization maintenance process. In addition, A-3
3 is synchronization word detection protection information having the same character as B-31.

The synchronization word detection protection circuit A-3 operates as follows.

First, in the synchronization recovery process (operation of the backward medical language control means), each time the synchronization word detection information B-13 is inputted in a continuous cycle, the counter is incremented to count the number of detections. If the synchronization word detection information B-13 is not input, the counter is reset as in the conventional case. In the present invention, the synchronization code is further detected by the station identification code detection information A-41 (outputted only when no station identification code is detected as described above) output from the station identification code detection circuit A-4. The counter of the detection protection circuit A-3 is reset. In other words, the number of detections is counted only when the synchronization word detection circuit B-1 indicates detection of a synchronization word and the station identification code detection circuit A-4 indicates detection of a station identification code.

By the above measures, it is possible to monitor the determination of the synchronization word detection more reliably, and it is also possible to prevent the synchronization 1 return operation from being redone due to erroneous detection or the like, and it is possible to prevent synchronization pull-in from taking a long time. Note that by resetting the counter, synchronization 1 can be reset as before.
Synchronous word detection protection information B that includes redoing the summer return movement
-31 and A-33 are respectively sent.

Then, when the count value of the counter satisfies the predetermined value,
As before, synchronization word detection protection information (first synchronization word detection 1 protection information) B-31, the content of which is the end of the backward protection operation.
Doujin-33 is sent out respectively. As a result, the synchronization word detection circuit B-1 and the station identification code detection circuit A-4 enter the synchronization maintenance process, and the station identification code detection circuit A-4 outputs the received signal B-12 which is data information. become.

Next, in the synchronization maintenance process (operation of the forward protection means), the processing for the synchronization word detection information B-13 is the same as before, but a counter is set to count non-detections and before it reaches a predetermined value. When station identification code detection information A-41 containing station identification code detection is input, the counter is reset to 1 at that point to maintain synchronization. In other words, the number of non-detections is counted only when the synchronization word detection information B-13 indicates that the synchronization word is not detected and the station identification code detection information A-41 indicates that the station identification code is not detected.

This is important in maintaining synchronization, as it prevents unnecessary erroneous detection and also monitors reconfirmation of synchronization word detection.

Note that when the undetected count value satisfies a predetermined value, it is the same as the conventional method.

In the embodiment described above, an existing station identification code is used as the specific code word, but the present invention is not limited to this, and any code word other than the synchronization word of the control information part of the transmission frame may be used. Alternatively, it may be specially added and set to the control information section.

(Effects of the Invention) As detailed above, according to the synchronization word detection confirmation monitoring method of the present invention, a specific code word for detection is set in addition to the detection synchronization word, and the synchronization word is detected from the received signal. At this time, each bit pattern of the synchronization word for detection and the specific code word for detection is compared bit by bit with the received signal, and if both the synchronization word and the specific code word cannot be detected during the synchronization recovery process, normal backward protection is performed. This method reduces the chance of having to redo the synchronization return operation fP due to false detection, etc., and as a result, it takes less time to pull in synchronization, and it also allows for more reliable detection of synchronization words. It also has the effect of allowing for monitoring.

In addition, in the synchronization maintenance process, normal forward protection is entered only when both the synchronization word and the specific code word are not detected, which has the effect of keeping the probability of synchronization loss due to non-detection to a low level. It also serves as a reconfirmation monitor for synchronization word detection, which has an important effect in maintaining synchronization. Note that, according to the present invention, there is an advantage that both the front and rear cA protection systems can be used as they are.

[Brief explanation of the drawing]

1 is a block diagram of a configuration of a synchronization word detection and confirmation monitoring system according to an embodiment of the present invention, and FIG. 2 is a configuration block diagram of a conventional synchronization word detection and monitoring system 7B-1.・Synchronization word detection circuit, B-2...Synchronization word permissible error number setting circuit, A-3, B-3...Synchronization word detection protection circuit, A-4...・Station identification code detection circuit,
A-5... Station identification code allowable error number setting circuit,
B-11B-12... Received signal, B-13...
... Synchronization word detection information, B-21 ... Synchronization word allowable error number setting information, A-33, B-31゜B-3
2... Synchronous word detection protection information, A-41...
...Station identification code detection information, A-51...Station identification code allowable error number setting information. Agent: Patent Attorney Yoshi Hachiman Hiroki is introduced in a fixed period, and Hagiku is sure to be present.
Figure Conventional 0 Synchronous Words / I Searching and Reading J Type ゛ wo Keeper 4th Edition 2nd Figure Procedure Amendment (Voluntary) January 9, 1985

Claims (1)

[Claims] A synchronization word detection confirmation monitoring method in a digital communication system that detects a synchronization word from a received signal that is received and demodulated at a constant cycle, and confirms the detection of the synchronization word again for monitoring; A detection synchronization word consisting of the same bit pattern as the synchronization word to be detected is set in advance,
Synchronization word detection means that performs a bit-by-bit comparison between the detection synchronization word and the received signal and outputs synchronization word detection information indicating whether the number of mismatching bits is within the range of the synchronization word allowable error number; A specific code word for detection that has the same bit pattern as a specific code word that is included in the received signal and has a bit pattern different from the synchronization word is set in advance, and the specific code word for detection and the received signal specific code word detection means that performs bit-by-bit comparison with the specified code word and outputs specific code word detection information indicating whether the number of mismatching bits is within the range of the specific code word allowable error number; The number of detections is counted only when the word detection information indicates synchronous word detection and the specific code word detection information indicates specific code word detection, and when the counted value satisfies a predetermined value, the synchronous word detection means and Backward protection control means for outputting first synchronization word detection protection information to the specific code word detection means; in the synchronization maintenance process, the synchronization word detection information indicates non-detection of a synchronization word, and the specific code word detection information specifies Count the number of code word non-detections only when the code word is non-detected,
A forward protection control means for outputting second synchronization word detection protection information to the synchronization word detection means and the specific code word detection means when the count value satisfies a predetermined value; Detection confirmed monitoring method.