KR101972798B1 - Network Time Protocol based Time synchronization apparatus and method - Google Patents

Abstract

The present invention relates to an NTP time synchronization apparatus and method with minimized error, and minimizes errors and accumulation when using NTP time synchronization through a network, thereby preventing temporal jumping.

Description

[0001] NTP Time Synchronization Apparatus and Method [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time synchronization technique between devices connected to a network, and more particularly to a synchronization technique based on a Network Time Protocol.

In the exchange of information between network devices, or in which one device needs to synchronize the clock or time of these devices in order to correctly process the information collected from other devices. In a time synchronizing technique in a network system, a technique in which each device corrects a time through a contact signal of a predetermined period distributed by a host device capable of generating a correct standard time through reception of a reference signal such as a GPS signal .

There is a technique disclosed in Korean Patent Registration No. 10-1290785, filed by the present applicant and registered on July 23, 2013, with regard to a technique of correcting time by distributing a contact signal. This technique minimizes the temporal jump phenomenon due to the rapid correction of the clock by compensating the calculated error several times by the minimum time unit of the system within the error measurement period. For example, if the period during which the pulse signal is received from the external synchronizing device is 10 sec, the error generated during this period is 4 msec, and the minimum time unit of the system is 1 msec, The correction is performed four times in increments of 1 msec every 2.5 seconds, which is equal intervals.

In a case where the contact signal can not be used, or when a very precise time synchronization is not required, there is a method of synchronizing the time using NTP (Network Time Protocol) over the network. In this specification, the NTP method refers to transmission and reception of time information in a client-server or a peer-to-peer manner, for example, a packet called a timestamp in a standard protocol Means a time synchronization technique between the network terminals. Thus, the term NTP refers to a technique for synchronizing the time between network terminals through distribution or delivery of packets containing time information over a network rather than a standard.

The time synchronization technique of the NTP scheme generates an error according to the state of the network. If the time having the error is immediately applied, the time synchronization is set to a different time each time the NTP response is received. . That is, in the case of the NTP scheme, a time synchronization error of a terminal occurs as an internal factor of the terminal, but may occur due to a delay or an irregular occurrence in a transmission path on a network. When such an error rapidly varies, The time synchronization of the time synchronization device may still occur.

Korean Patent No. 10-1290785 (Jul. 23, 2013)

An object of the present invention is to provide a time synchronizing apparatus and method of an NTP system that can minimize time-jumping by minimizing error and accumulation when using NTP-type time synchronization.

According to an aspect of the present invention, an NTP time synchronization apparatus includes an internal timer for measuring an internal time, a standard time receiver for receiving a standard time from an NTP server, and a timer for receiving a standard time and an internal timer received by the standard time receiver An error correction period determination unit for determining a period of a plurality of times of the error measurement period as an error correction application period; a time error calculation unit for calculating a time error calculated by the error calculation unit; Is divided into a minimum time unit and an error correction unit that corrects an error by distributing the internal time measured by the internal timer by a minimum time unit at a time interval obtained by dividing the error correction application period determined by the error correction application period determining unit do.

According to a further aspect of the present invention, the error measurement period may be a period of receiving standard time from an NTP server.

According to a further aspect of the present invention, when the time error calculated by the error calculator is equal to or greater than the error measurement period, the internal time can be changed to the standard time received by the standard time receiver.

According to another aspect of the present invention, an NTP time synchronization method minimizing an error includes a standard time reception step in which the NTP time synchronization device receives a standard time from an NTP server, and a step in which the NTP time synchronization device receives An error calculation step of calculating a time error by comparing the standard time and the internal time measured by the internal timer, and a step of calculating an error correction value by dividing the time error calculated by the NTP time synchronization device by the minimum time unit And an error correction step of performing error correction by distributing the internal time measured by the internal timer by a minimum time unit at a time interval obtained by dividing the period.

According to a further aspect of the present invention, the NTP time synchronization method in which the error is minimized may further include an error correction application period determination step in which the NTP time synchronization device determines a plurality of cycles of the error measurement period as the error correction application period .

According to a further aspect of the present invention, the error measurement period may be a period of receiving standard time from an NTP server.

According to a further aspect of the present invention, in the error correction step, when the time error calculated by the error calculation step of the NTP time synchronization device is equal to or greater than the error measurement period, the internal time can be changed to the standard time received by the standard time reception step have.

The present invention minimizes errors and accumulation in the case of using NTP time synchronization through a network, thereby preventing temporal jumping, thereby enabling reliable time synchronization.

1 is a network configuration diagram of an NTP time synchronization system according to the present invention.
FIG. 2 is a block diagram showing a configuration of an embodiment of an NTP time synchronization apparatus minimizing an error according to the present invention.
FIG. 3 is a view for explaining a time error correction of the NTP time synchronizer in which the error according to the present invention is minimized.
FIG. 4 is a flowchart showing a configuration of an embodiment of an NTP time synchronization method in which an error according to the present invention is minimized.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. While specific embodiments have been illustrated and described in the accompanying drawings, it is not intended that the various embodiments of the invention be limited to any particular form.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Hereinafter, an electronic device according to various embodiments in which aspects of the proposed invention are implemented will be described with reference to the accompanying drawings.

1 is a network configuration diagram of an NTP time synchronization system according to the present invention. As shown in FIG. 1, the NTP time synchronization system according to the present invention includes at least one electronic device 10 equipped with an NTP time synchronization device 100 for performing NTP (Network Time Protocol) -based time synchronization, An NTP server 20 operating as a GM (Grand Master) that provides accurate standard time to the device 10 is connected and configured through a network.

NTP (Network Time Protocol) is a protocol used for time synchronization between a client (electronic device) and a server (NTP server) on a network. An electronic device receives accurate standard time information from an NTP server for time synchronization, .

The time synchronization using the NTP causes an error according to the state of the network. When the time having the error is immediately applied to the electronic device 10, the time is set to a different time each time a response of the NTP is received, Resulting in a temporal jump phenomenon.

That is, the time synchronization error in the case of using the NTP may be caused by an internal factor of the NTP time synchronization device 100 mounted in the electronic device 10, but may be caused by a delay occurring irregularly on the network, If the error is rapidly corrected, the NTP time synchronization device 100 mounted on the electronic device 10 may experience a temporal jump phenomenon.

Accordingly, an NTP time synchronization apparatus capable of minimizing errors and accumulation in case of NTP time synchronization via a network and preventing a temporal jump will be described with reference to FIG.

FIG. 2 is a block diagram showing a configuration of an embodiment of an NTP time synchronization apparatus minimizing an error according to the present invention. The NTP time synchronization apparatus 100 minimizing the error according to this embodiment is mounted on an electronic device 10 receiving a standard time from an NTP server 20 operating as a GM (Grand Master) that provides accurate standard time The internal time used in the electronic device 10 is corrected using the standard time.

For example, the electronic device 10 may be the equipment constituting the distributed control system of the nuclear power plant, and the NTP time synchronization device 100 minimizing the error may be installed in the equipment constituting the distributed control system of the nuclear power plant, The time can be implemented to correct based on standard time.

2, the NTP time synchronization apparatus 100 minimizing the error according to this embodiment includes an internal timer 110, a standard time receiver 120, an error calculator 130, An application period determination unit 140, and an error correction unit 150. [

The internal timer 110 measures the internal time. The internal timer 110 has a clock inside, measures time using the clock, and outputs time information. The clock in the internal timer 110 may be a very precise clock, such as an atomic clock, which requires little or no error correction. However, since an inaccurate clock is used due to a cost problem or the like, Synchronize at standard time.

The standard time receiving unit 120 receives the standard time from the NTP server. An error occurs in the internal time over time due to an internal factor of the internal timer 110. An accurate standard time is required to correct the error and an accurate standard time is transmitted to the NTP server 120 through the standard time receiver 120. [ Lt; / RTI >

In this case, the NTP time synchronization apparatus 100 having minimized error may actively request the NTP server to periodically receive the standard time and receive the standard time to the NTP server. Alternatively, the NTP server may periodically The minimized NTP time synchronization apparatus 100 may be implemented such that the NTP time synchronization apparatus 100 minimizing the error receives the standard time manually.

The error calculator 130 calculates a time error by comparing the standard time received by the standard time receiver 120 with the internal time measured by the internal timer 110. [

The standard time received by the standard time receiver 120 is a standard time at the time when the NTP server transmits the standard time and the internal time measured by the internal timer 110 is the internal time at the time when the standard time is received from the NTP server Time, the standard time and the internal time cause a time error, which is caused by an external factor such as the internal timer 110 itself and a network delay in which standard time is transmitted.

The error correction application period determination unit 140 determines a plurality of periods of the error measurement period as the error correction application period. In this case, the error measurement period may be a period for receiving the standard time from the NTP server.

In case of applying the time having the error to the electronic device 10 immediately, the NTP based time synchronization is set to a different time each time a response of the NTP is received, and the time axis is shaken. A temporal jump phenomenon occurs.

That is, the time synchronization error in the case of using the NTP may be caused by an internal factor of the NTP time synchronization device 100 mounted in the electronic device 10, but may be caused by a delay occurring irregularly on the network, If the error is rapidly corrected, the NTP time synchronization device 100 mounted on the electronic device 10 may experience a temporal jump phenomenon.

In order to prevent this, an error correction application period determination unit 140 determines a period of a plurality of error measurement periods as an error correction application period. For example, if the error measurement period is T, the error correction application period determined through the error correction application period determination unit 140 becomes nT. In this case, n is a natural number of 2 or more, and can be set to be large when the network fluctuation factor is large, and small when the network fluctuation factor is small.

The error correction unit 150 divides the time error calculated by the error calculation unit 130 by a minimum time unit and divides the error correction application period determined by the error correction application period determination unit 140 by a time interval, The internal time measured by the internal timer 110 is distributed by a minimum time unit to perform error correction.

If the time error calculated by the error calculator 130 is t and the minimum time unit is u, the error correction interval is d = nT / (t / u) = nTu / t, The correction unit 150 corrects the error correction interval d by the minimum time unit u time.

FIG. 3 is a view for explaining a time error correction of the NTP time synchronizer in which the error according to the present invention is minimized. For example, if the error measurement period is 10 sec, the error correction application period is 3 times the error measurement period, 30 sec, the calculated time error is 6 msec, and the minimum time unit is 1 msec, then the error correction interval is d = 3 * 10 sec * / 6 msec) = 5 sec.

Theoretically, the error of 6 times internal time should be corrected by 5 msec intervals in 5 sec intervals. However, since the error measurement interval is 10 secs, 2 msec internal time in 5 ms intervals and 1 msec minimum in 2 msec When the next standard time is corrected, the current internal time error correction is stopped and a new error correction process is performed again in the same manner as above using the new standard time and the previous error-corrected internal time from the new standard time reception time do.

If the error between the new standard time and the previous error corrected internal time is 4 msec, the error correction interval becomes d = 3 * 10 sec * (1 msec / 4 msec) = 7.5 sec. The internal time is corrected by 1 msec in 1 msec minimum time unit.

If the internal time error correction process is continuously repeated, the error of the NTP-based time synchronization which can not be precisely synchronized with the conventional contact-type time synchronization is minimized and accumulated, so that the visual jump of the NTP time synchronizer does not occur , NTP time synchronization with minimized error can be achieved.

According to a further aspect of the present invention, when the time error calculated by the error calculation unit 130 is equal to or greater than the error measurement period, the error correction unit 150 corrects the internal time And may be implemented to change the time.

In this case, since the time error calculated by the error calculation unit 130 is equal to or longer than the error measurement period, the difference between the standard time and the internal time is too large, meaning that there is no meaning to synchronize the internal time with the standard time through the NTP error correction. In this case, the internal time is changed to the standard time received by the standard time receiving unit 120 to initialize the internal time of the NTP time synchronizer.

The NTP time synchronization operation of the NTP time synchronization apparatus minimizing the error according to the present invention as described above will be described with reference to FIG. FIG. 4 is a flowchart showing a configuration of an embodiment of an NTP time synchronization method in which an error according to the present invention is minimized.

First, in the standard time reception step 210, the NTP time synchronization device receives the standard time from the NTP server. Since we have already discussed the reception of standard time, the redundant explanation is omitted.

Next, in the error calculation step 220, the NTP time synchronization device compares the standard time received by the standard time reception step 210 with the internal time measured by the internal timer to calculate the time error. Since we have already explained the time error calculation, redundant explanation is omitted.

Then, in the error correction step 230, the NTP time synchronization unit divides the time error calculated by the error calculation step 220 by the minimum time unit, and divides the error correction application period by the internal timer The error is compensated by distributing the measured internal time by the minimum time unit. Since the above description is related to the correction of the internal time error, redundant description is omitted.

According to a further aspect of the present invention, the NTP time synchronization method minimizing the error may further include an error correction application period determination step (225). In the error correction application period determination step 225, the NTP time synchronization apparatus determines a plurality of cycles of the error measurement period as an error correction application period. In this case, the error measurement period may be a period for receiving the standard time from the NTP server. The description of the period of application of the error correction application has been described earlier, so redundant description is omitted.

By implementing such a configuration, the present invention minimizes errors and accumulation in the case of using NTP time synchronization over a network, thereby preventing temporal jumping, thereby enabling reliable time synchronization.

According to a further aspect of the invention, in the error correction step 230, when the time error calculated by the NTP time synchronization unit 220 is greater than or equal to the error measurement period, And to change the internal time to the received standard time.

In this case, if the time error calculated by the error calculation step 220 is equal to or greater than the error measurement period, the difference between the standard time and the internal time is too large. If there is no meaning to synchronize the internal time with the standard time through the NTP error correction, The internal time is changed to the standard time received by the time receiving step 210 to initialize the internal time of the NTP time synchronizer so that the internal time matches the standard time.

As described above, the present invention minimizes error and accumulation in the case of using NTP time synchronization through a network to prevent temporal jumping, thereby enabling reliable time synchronization. Therefore, can do.

At least a portion of a device (e.g., modules or functions thereof) or a method (e.g., operations) according to various embodiments of the present invention may be stored in a computer-readable storage medium Storage Media).

An instruction, when executed by one or more processors, may perform one or more functions corresponding to the instruction. A computer-readable storage medium may be implemented (e.g., implemented) by at least a portion of a programming module, for example, by a processor. At least some of the programming modules may include, for example, modules, programs, routines, sets of instructions, or processes for performing one or more functions.

It is to be understood that the various embodiments disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of various embodiments of the present invention. Accordingly, the scope of the various embodiments of the present invention should not be limited to the above-described embodiments, and all changes or modifications derived from the technical ideas of various embodiments of the present invention are included in the scope of various embodiments of the present invention .

INDUSTRIAL APPLICABILITY The present invention is industrially applicable in the field of time synchronization technology and its application technology.

10: Electronic device
20: NTP server
100: NTP time synchronization device
110: internal timer
120: Standard time receiver
130:
140: error correction application period determining unit
150: error correction unit

Claims (7)

An internal timer for measuring an internal time;
A standard time receiver for receiving standard time from an NTP server;
An error calculator for calculating a time error t by comparing the standard time received by the standard time receiver with the internal time measured by the internal timer;
In order to prevent the visual jumping phenomenon occurring when the time error is corrected at intervals of the error measurement period (T), which is the period of receiving the standard time from the NTP server, the error correction period (nT) An error correction applying period determining unit for determining an error correction applying period;
The error correction application period nT determined by the error correction application period determination unit is divided by the error correction number t / u, which is a value obtained by dividing the time error t calculated by the error calculation unit by the minimum time unit u (T / u)), and calculates an internal time measured by the internal timer for each of the error correction intervals (d) during the error correction application period (nT) An error correcting unit for correcting an error by time unit (u);
NTP time synchronizer with minimized error. delete The method according to claim 1,
Error correction section:
An NTP time synchronizer that minimizes an error in changing the internal time to the standard time received by the standard time receiver when the time error calculated by the error calculator is equal to or greater than the error measurement period. A standard time receiving step in which the NTP time synchronization device receives a standard time from an NTP server;
An error calculation step of calculating a time error t by comparing the standard time received by the NTP time synchronizer with the internal time measured by the internal timer;
In order to prevent the visual jumping phenomenon occurring when the time error is corrected at the intervals of the error measurement period (T), which is the period of receiving the standard time from the NTP server, the NTP time synchronizer adjusts a plurality of cycles of the error measurement period as error correction An error correction applying period determining step of determining an application period nT;
The error correction application period nT determined by the NTP time synchronization device in the error correction application period determination step is set to an error correction number t in which the time error t calculated by the error calculation step is divided by the minimum time unit u / u) to calculate an error correction interval (d = nT / (t / u)) and calculate an internal time measured by the internal timer as an error correction interval d), and correcting the error by a minimum time unit (u);
NTP time synchronization method minimizing the error included. delete delete 5. The method of claim 4,
In the error correction step:
Wherein the NTP time synchronization unit minimizes the error of changing the internal time to the standard time received by the standard time reception step when the time error calculated by the error calculation step is equal to or greater than the error measurement period.

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