WO2015146112A1

WO2015146112A1 - Time reference terminal, measurement terminal, time synchronization system, and time synchronization method

Info

Publication number: WO2015146112A1
Application number: PCT/JP2015/001593
Authority: WO
Inventors: 茂樹篠田; 佐々木　康弘; 翔平木下
Original assignee: 日本電気株式会社
Priority date: 2014-03-28
Filing date: 2015-03-20
Publication date: 2015-10-01
Also published as: JPWO2015146112A1; JP6436164B2

Abstract

This invention provides a time reference terminal and the like whereby measurement time intervals and variations in a communication environment do not bring about factors that cause measurement error and power consumption is thus reduced. The time reference terminal (24) in this time synchronization system is connected to one or more processing terminals that start prescribed processing at a predetermined processing-start time. Said time reference terminal (24) is provided with an operation-start instruction unit (24a) and a synchronization processing unit (24c). The operation-start instruction unit (24a) transmits, to each of the processing terminals, a signal that instructs the processing terminals to not start processing until the processing-start time. For each processing terminal, the synchronization processing unit (24c) performs a synchronization process so as to synchronize said processing terminal with the time reference terminal (24) such that said synchronization process completes before the processing-start time by the amount of time between the current time and the processing-start time corresponding to the precision of a clock associated with the operations performed by that processing terminal.

Description

Time reference terminal, measurement terminal, time synchronization system, and time synchronization method

The present invention relates to a time reference terminal, a measurement terminal, a time synchronization system, and a time synchronization method.

A measurement terminal equipped with a sensing function and a communication function used in a sensor network or the like requires high accuracy in time synchronization between the measurement terminals. In addition, since these measurement terminals are often installed in places where it is difficult to secure commercial power, the amount of power is limited and battery driving is required. On the other hand, Patent Document 1 discloses a method for reducing power consumption for this reason without waiting for a long time to receive a time synchronization signal.

Further, Patent Document 2 discloses a technique for detecting and detecting a leaking portion using a correlation method when water, oil, gas, or the like leaks from a specific position of a pipe.

JP 2006-74326 A JP 58-208636 A

In a sensor network in which each measurement terminal performs wireless communication using battery drive, it is necessary to synchronize the measurement terminals with low power for long-term operation of each measurement terminal. For example, in the time synchronization method described in Patent Document 1, in order to achieve time synchronization with low power, wireless communication with high power consumption is performed by periodically performing time synchronization processing between time-managed terminals. Suppress the frequency of execution. However, an error occurs in the count time due to the clock accuracy mounted on the measurement terminal. For this reason, if the reference terminal increases the interval between the synchronization time and the actual measurement time, the measurement start time error increases, and if the interval between the synchronization time and the measurement time is shortened, the measurement start time is exceeded. There is a problem.

Further, the position specifying method using the correlation processing described in Patent Document 2 is based on the premise that the time waveforms acquired between two different points are completely synchronized, and this time waveform is used in actual operation. It is necessary to suppress the synchronization error. However, when sensor terminals are installed outdoors over a wide area and wireless communication is used for measurement data transmission, there is a problem that power consumption increases due to a decrease in synchronization error due to changes in the communication environment and high load operation of the sensor terminals. There is.

The present invention was made to solve the above problems. The main object of the present invention is to provide a time reference terminal or the like that can obtain high synchronization accuracy and realize low power consumption without fluctuations in the communication environment and measurement time intervals being a cause of measurement errors. To do.

In order to solve the above problems, the first aspect of the present invention is to
A time reference terminal connected to at least one processing terminal that starts a predetermined process at a process start time that is a predetermined time;
An operation start instruction means for transmitting a signal instructing not to start the processing until the processing start time to each of the processing terminals;
Synchronous processing is performed with each processing terminal so that the time corresponding to the accuracy of the clock related to each operation of the processing terminal is completed prior to the processing start time in the time from the current time to the processing start time. It is a time reference terminal provided with the synchronous process means to do.

The second aspect of the present invention is:
A processing terminal connected to a time reference terminal for instructing to start a predetermined process at a processing start time that is a predetermined time;
Waiting means waiting for the start of processing until the processing start time;
Synchronization processing means for performing synchronization processing with the time reference terminal at the synchronization start time notified from the time reference terminal;
It is a processing terminal provided with the processing means which starts a process at a process start time.

The third aspect of the present invention is:
It is a time synchronization system provided with the time reference terminal described in any of the above, and the processing terminal described in any of the above.

The fourth aspect of the present invention is:
A time synchronization method performed by a time reference terminal connected to at least one processing terminal that starts predetermined processing at a processing start time that is a predetermined time,
A signal indicating that the processing is not started until the processing start time is transmitted to each of the processing terminals;
Synchronous processing is performed with each processing terminal so that the time corresponding to the accuracy of the clock related to each operation of the processing terminal is completed prior to the processing start time in the time from the current time to the processing start time. To prepare to
This is a time synchronization method.

The fifth aspect of the present invention is:
A time synchronization method performed by at least one processing terminal connected to a time reference terminal instructing to start a predetermined process at a processing start time that is a predetermined time,
Wait for the start of processing until the processing start time,
Perform synchronization processing with the time reference terminal at the synchronization start time notified from the time reference terminal,
Comprising starting processing at a processing start time;
This is a time synchronization method.

According to the time reference terminal or the like of the present invention, a change in communication environment and a measurement time interval do not cause measurement errors, so that high synchronization accuracy can be obtained and low power consumption can be realized.

It is a figure which shows the structure of the time synchronization system which concerns on 1st embodiment of this invention. It is a figure which shows an example of a function structure of the time reference terminal in 1st embodiment. It is a figure which shows an example of a function structure of the measurement terminal in 1st embodiment. It is a figure for demonstrating the concept of the time of the time reference terminal and measurement terminal in 1st embodiment. It is a flowchart of operation | movement of the time synchronization system which concerns on 1st embodiment. It is a figure which shows the structure of the time synchronization system which concerns on 2nd embodiment of this invention. It is a flowchart which shows operation | movement of the time synchronous process which concerns on 2nd embodiment. It is an internal block diagram of the time reference terminal of the time synchronization system which concerns on 3rd embodiment of this invention. It is an internal block diagram of the measuring terminal of the time synchronization system which concerns on 3rd embodiment. It is a flowchart which shows operation | movement of the time synchronous process which concerns on 3rd embodiment. It is a figure which shows the concept of the clock pulse between flags in 3rd embodiment. It is a figure which shows the concept of the counter value between flags in 3rd embodiment. It is a graph which shows the relationship between the frequency | count of flag transmission in 3rd embodiment, and a counter value. It is a graph which shows the communication processing of the time reference terminal and each measurement terminal in 3rd embodiment in time series. It is a graph which shows the synchronization error without clock correction. It is a graph which shows the synchronization error with a clock correction. It is a figure which shows the structure of the time reference terminal which concerns on 4th embodiment of this invention. It is a figure which shows the structure of the processing terminal which concerns on 5th embodiment of this invention. It is a figure which shows the structure of the time synchronization system which concerns on 6th embodiment of this invention.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic. Furthermore, it should be noted that the embodiment described below is an example, and can be appropriately changed within the scope of the same essence.

Further, in the following description of the embodiments, each component of each device indicates a functional unit block, not a hardware unit configuration. The hardware of each device includes a CPU (Central Processing Unit) of an arbitrary computer and a memory for loading a program as its components. Further, the hardware components include a storage medium such as a hard disk for storing the program and a network connection interface.

Each device is realized by hardware, software, or an arbitrary combination of these components. There are various modifications to the implementation method and the like. For example, in addition to the CPU, an MPU (Micro-processing unit) or MCU (Micro Controller Unit) may be used.
<First embodiment>
(Time synchronization system)
The time synchronization system 1 according to the first embodiment is a system that synchronizes measurement start times between measurement terminals. As shown in FIG. 1, the time reference terminal 20 and a plurality of measurement terminals 10 (10a, 10b, 10c ...). One or more time reference terminals 20 exist in the time synchronization system 1. The time reference terminal 20 and the

measurement terminals

10a, 10b, and 10c can communicate with each other via the communication network 7. In many cases, communication between the measurement terminals 10a to 10c and the communication network 7 is performed wirelessly, and the measurement terminals 10a to 10c consume a large amount of power during the wireless communication.
(Time reference terminal)
As shown in FIG. 2, the time reference terminal 20 includes a measurement start time setting unit 100, a measurement interval calculation unit 110, a clock accuracy storage unit 120, a maximum error time calculation unit 130, a synchronization start time setting unit 140, and an operation start instruction unit. 150, a synchronization processing unit 170, a measurement start time storage unit 180, a remaining time setting unit 190, a transmission / reception unit 160, and the like.

The measurement start time setting unit 100 prompts a user who is an administrator of the time synchronization system 1 to set the measurement start time. The measurement start time storage unit 180 stores the set measurement start time. The measurement interval calculation unit 110 calculates a measurement interval from an operation start time that is a preset measurement start time and the current time. The clock accuracy storage unit 120 stores clock accuracy information, which is information related to an allowable error (hereinafter referred to as “clock accuracy”) of the clock frequency of each measurement terminal 10a to 10c. The maximum error time calculation unit 130 calculates the maximum error time of each measurement terminal 10a to 10c based on the measurement interval and the clock accuracy information.

The synchronization start time setting unit 140 calculates the synchronization start time so that synchronization is performed immediately before the measurement start time based on the measurement start time, the maximum error time, and the synchronization processing time that is the time required for synchronization. . The operation start instruction unit 150 transmits an instruction indicating operation standby to each of the measurement terminals 10a to 10c. The synchronization start time storage unit 141 stores the synchronization start time. The synchronization processing unit 170 performs time synchronization processing with each of the measurement terminals 10a to 10c at the synchronization start time. The remaining time setting unit 190 calculates the remaining time up to the measurement start time from the synchronization processing time and the measurement start time. The remaining time setting unit 190 sets the calculated remaining time in each of the measurement terminals 10a to 10c via wireless communication. The transmission / reception unit 160 performs wireless communication with the measurement terminals 10a to 10c via the communication network 7.
(Measurement terminal)
As shown in FIG. 3, the measurement terminals 10a to 10c include a measurement standby unit 200, a synchronization processing unit 210, a measurement processing unit 220, a transmission / reception unit 230, a synchronization start time storage unit 240, a remaining time storage unit 250, and the like. . The measurement standby unit 200 turns off the peripheral functions in response to an operation standby instruction from the time reference terminal 20, and maintains the off state until the synchronization start time or the measurement start time. The synchronization processing unit 210 performs time synchronization with the time reference terminal 10 at the synchronization start time. The measurement processing unit 220 performs various measurement processes, for example, measurement of a leakage position of a pipe. Examples of the sensor used for measurement by the measurement processing unit 220 include a vibration sensor, a temperature sensor, and a pressure sensor. The transmission / reception unit 230 performs wireless communication with the time reference terminal 20 via the communication network 7. Note that this may be wired communication. The synchronization start time storage unit 240 is a memory that temporarily stores the synchronization start time. The remaining time storage unit 250 is a memory that temporarily stores the remaining time.

Note that the above-described units are stored in a CPU or the like of a computer (not shown). Alternatively, it is stored in a ROM (Read Only Memory) or a RAM (Random Access Memory) (not shown), and these processes are executed by the CPU appropriately performing arithmetic processing.
(Time synchronization system operation)
Each time and each time used in the time synchronization system 1 will be described with reference to operations in time series between the time reference terminal 20 and the measurement terminals 10a to 10c. In FIG. 4, t represents a time axis.

First, as shown in FIG. 4, the measurement interval 32 to be set in the measurement terminals 10a to 10c is calculated from the measurement start time 30 set in the time reference terminal 20 and the operation start time 31 which is the current time.

Here, the clock accuracy of general measuring terminals 10a to 10c is about ± several tens of ppm (parts per million), and assuming that ± 100 ppm, the error time per day is about ± 10 seconds. Naturally, if the measurement interval 32 is set to be longer, the error time becomes longer. For example, consider a case where the allowable error of the clock frequency is a negative value (for example, the clock accuracy is −100 ppm) and the measurement start time is one day later. In this case, the actual measurement start time is 10 seconds later than the schedule and exceeds the original measurement start time 30.

Therefore, in the present embodiment, of the accuracy information (hereinafter referred to as “catalog value”) described in the product catalog of each measurement terminal 10a to 10c, the maximum absolute value of the negative clock accuracy value (hereinafter referred to as “minimum catalog value”). Based on this, the maximum error time 33, which is the result of multiplying the measurement interval 32 by the minimum catalog value, is calculated. For example, if the measurement interval 32 is 24 hours and the minimum catalog value is | −100 ppm |, 24 hours × 60 minutes × 60 seconds × | −100 ppm | / 10 ⁶ = 8.6 seconds. However, “||” represents an absolute value, and “/” represents division. Here, the time obtained by subtracting the maximum error time 33 and the synchronization processing time 34 from the measurement start time 30 is the synchronization start time 35.

Thus, the synchronization start process 36 is executed before the measurement start time 30 in all the measurement terminals 10a to 10c communicating with the time reference terminal 20, regardless of individual differences in clock accuracy. Thereafter, a remaining time 37, which is a result of subtracting the measurement start time 30 from the time when the synchronization processing time 34 has elapsed from the synchronization start time 35, that is, the synchronization processing completion time, is calculated. Then, the measurement start time 30 at which the measurement terminals 10a to 10c should start the measurement process 38 is the time after the remaining time 37 has elapsed from the synchronization process completion time.

Next, the operation of each part of the time synchronization system 1 according to the present embodiment will be described with reference to the flowchart of FIG.

(A) In step S100, the measurement start time setting unit 100 on the time reference terminal 20 side in FIG. 2 sets the measurement start time. Specifically, the measurement start time setting unit 100 prompts a user such as a system administrator to input and set a measurement start time to be set in the time reference terminal 20. In step S <b> 110, the measurement start time setting unit 100 stores the set measurement start time 30 in the measurement start time storage unit 180.

(B) In step S120, the measurement interval calculation unit 110 calculates a measurement interval from the operation start time 31 to the measurement start time 30. In step S130, the maximum error time calculation unit 130 uses the calculated measurement interval 32 and the clock accuracy information of each measurement terminal 10a to 10c previously stored in the clock accuracy storage unit 120 for each measurement terminal. Calculate the maximum error time. In step S140, the synchronization start time setting unit 140 sets the time obtained by subtracting the maximum error time and the time required for the synchronization process from the measurement start time 30 as the synchronization start time 35 to the measurement terminals 10a to 10c via the communication network 7. To send. Further, the synchronization start time setting unit 140 stores the synchronization start time 35 in the synchronization start time storage unit 141.

(C) Next, in step S141, when the transmission / reception unit 230 on the measurement terminals 10a to 10c side in FIG. 3 receives the synchronization start time 35, the measurement standby unit 200 uses the received synchronization start time 35 as the synchronization start time. Store in the storage unit 240. Thereafter, the measurement standby unit 200 turns off all unnecessary peripheral functions such as the communication function, and puts the measurement terminals 10a to 10c in the measurement standby state.

In step S160, when it is determined that the measurement standby unit 200 has reached the synchronization start time stored in the synchronization start time storage unit 240 (YES in step S160), in step S170, the synchronization processing unit 210 includes the time reference terminal 20 and The synchronization process is started via the communication network 7. If it is determined in step S160 that it is not the synchronization time (NO in step S160), the process returns to step S150 and the measurement standby state continues. However, when it is not the synchronization time, the process may return to the determination whether the synchronization time is reached (step S160) without returning to step S150.

Specifically, the synchronization processing unit 170 of the time reference terminal 20 transmits a synchronization signal to the measurement terminals 10a to 10c. In response to this, the synchronization processing unit 210 of the measurement terminals 10a to 10c returns a synchronization signal to the time reference terminal 20. This synchronization signal transmission / reception timing is set by the synchronization start time setting unit 140 to be performed immediately before the measurement start time. Since the synchronization error increases as time elapses, an accurate remaining time can be calculated by performing the synchronization process immediately before the measurement start time 30 in this way.

(D) In step S171, when the synchronization processing unit 170 in FIG. 2 determines that the synchronization start time stored in the synchronization start time storage unit 141 has come, the measurement terminals 10a to 10c and the communication network 7 Start synchronous processing. In step S180, after the synchronization process is completed, the remaining time setting unit 190 calculates a remaining time 37 that is a result of subtracting the measurement start time 30 from the synchronization process completion time of each measurement terminal 10a to 10c. The time 37 is transmitted to each of the measurement terminals 10a to 10c via the communication network 7.

(E) When the transmission / reception unit 230 on the measurement terminal side in FIG. 3 receives the remaining time 37 via the communication network 7 in step S181, the measurement standby unit 200 stores the received remaining time 37 in the remaining time storage unit 250. . Thereafter, in step S190, the measurement standby unit 200 again turns off all unnecessary peripheral functions represented by the communication function, and sets the measurement terminals 10a to 10c to the measurement standby state. In step S200, when the measurement processing unit 220 determines that the remaining time stored in the remaining time storage unit 250 has elapsed and has reached the measurement start time 30, the measurement processing unit 220 executes various measurement processes in step S210. To do.

As described above, according to the first embodiment of the present invention, the time synchronization system 1 has the highest measurement start time within a range that does not exceed the measurement start time no matter what the measurement start time is set. The closest synchronization start time is automatically set once. As a result, the time synchronization system 1 can reduce power consumption for synchronization processing and maintain higher synchronization compared to the case where synchronization processing is performed a plurality of times in a relatively short cycle. Accuracy can be achieved.
<Second Embodiment>
(Time synchronization system)
The time synchronization system (not shown) according to the second embodiment includes a time reference terminal 21 and a plurality of measurement terminals (not shown) for measurement that can communicate with the time reference terminal 21 as in the time synchronization system 1 of FIG. I have.

As shown in FIG. 6, the time reference terminal 21 has the following configuration.
Measurement start time setting unit 300,
Measurement interval calculator 310,
Clock accuracy storage unit 320,
Maximum error time calculator 330,
Synchronization start time setting unit 340,
Synchronization start time storage unit 341,
Operation start instruction unit 350,
Synchronization processor 370,
Clock accuracy measurement unit 371,
Measurement start time storage unit 380,
A remaining correction time setting unit 390 and a transmission / reception unit 360.

The synchronization start time storage unit 341 temporarily stores a reference synchronization start time and an actual measurement synchronization start time that is a time at which each synchronization terminal actually starts the synchronization process. The clock accuracy storage unit 320 stores information on the reference clock accuracy obtained from the catalog value for each measurement terminal and information on the actual clock accuracy obtained as a result of actual measurement.

The clock accuracy actual measurement unit 371 acquires the time at which the synchronization processing is actually started at each measurement terminal, and based on the acquired actual measurement time and the synchronization start time stored in the synchronization start time storage unit 341, each measurement Measure the clock accuracy of the device and calculate the measured clock accuracy. The remaining correction time setting unit 390 corrects the time from the completion of the synchronization process to the measurement start time based on the actually measured clock accuracy.

In addition, since it is the same as that of 1st embodiment about other each part, description is omitted.

Next, the operation of each part of the time synchronization system according to the second embodiment will be described with reference to the flowchart of FIG.
(A) In step S300, the measurement start time setting unit 300 on the time reference terminal side in FIG. 6 sets a measurement start time to be set in the time reference terminal 21. Specifically, the measurement start time setting unit 300 prompts the user or the like to input and set the measurement start time. In step S <b> 310, the measurement start time setting unit 300 stores the set measurement start time in the measurement start time storage unit 380.
(B) In step S320, the measurement interval calculation unit 310 calculates a measurement interval from the operation start time to the measurement start time. In step S330, the maximum error time calculation unit 330 acquires information indicating the reference clock accuracy from the clock accuracy storage unit 320, and calculates the maximum error time based on the measurement interval and the reference clock accuracy information of each measurement terminal. . In step S340, the synchronization start time setting unit 340 transmits a time obtained by subtracting the maximum error time and the time required for the synchronization process from the measurement start time to each measurement terminal via the communication network 7 as the synchronization start time. Further, the synchronization start time setting unit 340 stores the synchronization start time in the synchronization start time storage unit 341.
(C) Next, when each measurement terminal receives the synchronization start time in step S341, the measurement standby unit 200 of the measurement terminal turns off the power of the communication function or the like and puts its own terminal in the measurement standby state (step S350). . If it is determined in step S360 that the measurement standby unit 200 has reached the synchronization start time, the synchronization processing unit 210 performs synchronization processing with the time reference terminal 21 in step S370.
(D) When the synchronization processing between the time reference terminal 21 and each measurement terminal is completed in step S371, the clock accuracy measurement unit 371 in FIG. 6 actually starts the synchronization processing in each measurement terminal in step S372. The obtained time is acquired via the communication network 7. In step S373, the clock accuracy measurement unit 371 compares the acquired actual synchronization start time with the reference synchronization start time stored in the synchronization start time storage unit 341, and measures the clock accuracy of each measurement terminal. In step S380, the remaining correction time setting unit 390 calculates a remaining correction time by correcting the remaining time from the time immediately after the elapse of the synchronization processing time to the measurement start time according to the measurement result of the clock accuracy.

For example, if the delay time of a certain measurement terminal is 10 μs (microseconds) and the remaining time is 10 seconds until the measurement start time, 10s−10 μs is set as the corrected remaining time in the measurement terminal.

Steps S381 to S410 are the same as steps S181 to S210 in FIG.

As described above, according to the second embodiment of the present invention, the remaining time from the synchronization processing to the measurement start time is corrected with the actually measured clock accuracy unique to each measurement terminal device, thereby achieving higher synchronization accuracy. Can be obtained. As a result, according to this embodiment, time synchronization processing can be performed more accurately.
<Third embodiment>
The time synchronization system (not shown) of the third embodiment includes a time reference terminal 22 and a plurality of measurement terminals 11a to 11c, as in the time synchronization system 1 of FIG. The time reference terminal 22 and the measurement terminals 11a to 11c are connected to be communicable.

As shown in FIG. 8, the time reference terminal 22 has the following configuration.
Measurement start time setting section 400,
Measurement interval calculation unit 410,
Clock accuracy storage unit 420,
Maximum error time calculation unit 430,
Synchronization start time setting unit 440,
Synchronization start time storage unit 441,
Operation start instruction unit 450,
Synchronization processor 470,
Measurement start time storage unit 480,
A remaining time setting unit 490 and a transmission / reception unit 460.

The synchronization processing unit 470 includes a flag transmission unit 470a, a synchronization signal transmission unit 470b, a communication time setting unit 470c, and the like.

The flag transmission unit 470a transmits data (hereinafter referred to as “flag”) as a reception mark to the measurement terminals 11a to 11c at predetermined time intervals a predetermined number of times. The synchronization signal transmission unit 470b transmits a synchronization signal for synchronizing to the measurement terminals 11a to 11c. The communication time setting unit 470c sets the communication time between each of the time reference terminal 22 and the measurement terminals 11a to 11c, and calculates the remaining time until the measurement start time based on the set communication time.

As shown in FIG. 9, the measurement terminals 11a to 11c include a measurement standby unit 500, a synchronization processing unit 510, a measurement processing unit 520, a transmission / reception unit 530, a synchronization start time storage unit 540, a remaining time storage unit 550, and the like. . The synchronization processing unit 510 includes an average value calculation unit 510a, a threshold value determination unit 510b, a difference calculation unit 510c, a correction value calculation unit 510d, a synchronization signal transmission unit 510e, and the like.

The average value calculation unit 510a obtains a value (hereinafter referred to as “counter value”) obtained by counting clock pulses generated from the timing at which a certain flag is received until the next flag is received, and a plurality of counters are obtained. If there is a value, the average value is calculated. The threshold determination unit 510b determines whether the calculated average value is within a predetermined upper and lower threshold. The difference calculation unit 510c calculates a difference between the counter value of the time reference terminal 22 and the counter values of the measurement terminals 11a to 11c. The correction value calculation unit 510d calculates a correction value of a clock frequency (hereinafter also referred to as “operation clock”) related to the operation of the measurement terminals 11a to 11c based on the calculated difference. Here, the counter value and the operation clock have a reciprocal relationship, and in the present invention described by taking each embodiment as an example, the unit of the operation clock is not limited to hertz (Hz) based on “seconds”. The synchronization signal transmission unit 510e transmits a synchronization signal for synchronization from the measurement terminals 11a to 11c to the time reference terminal 22.

In addition, since each other part is the same as that of 1st and 2nd embodiment, description is abbreviate | omitted.

Next, the operation of each part in the time synchronization system of the third embodiment is other than the operation shown in the flowchart of FIG. 5 described in the first embodiment and the flowchart of FIG. 7 described in the second embodiment, and the synchronization operation. Is the same. Therefore, in the following, the synchronization operation in the time synchronization system of the third embodiment will be mainly described, and description of other steps will be omitted.

First, the outline of the synchronization operation in the time synchronization system of the third embodiment will be described (corresponding to steps S170 to S171 in FIG. 5 and steps S370 to S371 in FIG. 7). Note that the synchronization operation in the present embodiment is performed in order to obtain a round-trip communication time of a signal between the time reference terminal 22 and each of the measurement terminals 11a to 11c. By obtaining a difference in communication time between the time reference terminal 22 and each measurement terminal immediately before the start of the measurement operation, and correcting the remaining time until the measurement operation using this difference, each measurement terminal 11a to 11c At the same time, the measurement operation can be started.

Although not shown in FIGS. 8 and 9, the time reference terminal 22 and the measurement terminals 11a to 11c incorporate a reference oscillator for generating a reference clock. Each terminal generates a reference clock by multiplying a predetermined low frequency generated by a built-in reference oscillator as a source oscillation. When generating the reference clock, the frequency of the reference oscillator changes depending on the individual difference of the CPU, MPU or MCU to be used, and the environmental temperature change. Therefore, the synchronization processing unit 470 corrects the coefficient to be multiplied with the reference clock of the time reference terminal 22 as a reference, and matches the reference clock frequencies of the time reference terminal 22 and the measurement terminals 11a to 11c. Thus, the synchronization processing unit 470 obtains an accurate communication time difference between the time reference terminal 22 and each of the measurement terminals 11a to 11c, and corrects the measurement start time of each of the measurement terminals 11a to 11c with this communication time difference.

Hereinafter, the synchronization operation will be described in more detail with reference to the flowchart of FIG. Since other steps are the same as those in the first and second embodiments, description thereof will be omitted.

(A) First, in step S600, the flag transmission unit 470a of the time reference terminal 22 in FIG. 8 transmits the flag to the measurement terminals 11a to 11c a predetermined number n times. This is for examining the difference in the clock pulse period between the time reference terminal 22 and the measurement terminals 11a to 11c.

In the example shown in FIG. 11, while the time reference terminal 22 measures five clock pulses per second, the measurement terminals 11a to 11c measure four clock pulses, and the periods are different. 11, the case where the flag interval is 1 second has been described for convenience of explanation. However, the flag interval is not limited to only 1 second, and the time reference terminal 22 and the measurement terminal can be used at any flag interval. Eleven clock pulses may be counted.

(B) In step S610, when the average value calculation unit 510a of the measurement terminals 11a to 11c in FIG. 9 receives the flag, the average value calculation unit 510a acquires a counter value in a period between the timing at which the flag was previously received and the timing at which the flag was received this time.

For example, as shown in FIG. 12, if the clock pulse is generated four times before the flag 1 is received from the flag 2, the counter value a is 4. Similarly, the counter value b between the flag 2 and the flag 3 is 5, and the counter value c between the flag 3 and the flag 4 is 5. In FIG. 11, for convenience of explanation, measurement is performed at intervals of 1 second, but the flag interval is not limited to this.

FIG. 13 is a graph showing the relationship between the number n of flag transmissions transmitted by the flag transmission unit 470a and the counter value calculated by the average value calculation unit 510a in the third embodiment. In FIG. 13, it is assumed that the time reference terminal 22 transmits a flag to the measurement terminals 11a to 11c over the number of transmissions from 2 (n = 2) to 6 (n = 6). In this case, when n = 4, the flag is transmitted four times at regular intervals (see FIG. 12), and the measurement terminals 11a to 11c receive the counter value a between the first and second flags a (four times in FIG. 12). The counter value b between the second and third flags (five times in FIG. 12) and the counter value c between the third and fourth flags (five times in FIG. 12) are acquired. Next, in step S620, the average value calculation unit 510a calculates the average value of the received n counter values. For example, when n = 4 indicated by a broken line in FIG. 13, the average value calculation unit 510a calculates the average value of the counter values a, b, and c for three times.

(C) Next, in step S630, the threshold determination unit 510b compares the preset upper and lower thresholds with the calculated average value. The comparison with the threshold value is performed in order to check whether there is a large variation in the number of clock pulses between the flags. If the average value is within the upper and lower threshold values, the process proceeds to step S640. As a result of the comparison, if it is outside the upper and lower threshold range, the threshold determination unit 510b transmits a notification to the effect that it is out of the threshold range to the measurement terminal 22. In step S631, the flag transmission unit 470a of the measurement terminal 22 that has received this notification increases the number of flag transmissions by one. This is for obtaining a highly accurate counter value with the smallest possible number of transmissions when the variation in the counter value is predicted to increase. When the process of step S631 ends, the process returns to step S600.

For example, when the variation of the counter value is small, wireless communication with high power consumption is minimized by setting the number of flag transmissions as small as possible. On the other hand, when the variation is large, a highly accurate counter value with reduced variation is obtained by the counter value averaging process and the tolerance determination process. As a result, time synchronization with low power consumption can be performed while maintaining constant accuracy.

(D) In step S640, the difference calculation unit 510c calculates the clock frequency of the measurement terminals 11a to 11c based on the average value of the inter-flag counter, and calculates the difference between the clock frequencies of the time reference terminal 22 and the measurement terminals 11a to 11c. calculate.

As an example, based on the ACLK (Auxiliary Clock), MCLK (MasterClock), and SMCLK (SubmainClock), which are the reference clocks of the microcontroller, the frequency of the master clock of the time reference terminal 22 and the master clock of the measurement terminals 11a to 11c The difference with the frequency is calculated. Here, ACLK = reference clock frequency, MCLK = α × ACLK, SMCLK = MCLK / β, and the reference clock frequency value, α value, and β value are initialized.

The frequency difference between the master clock frequency of the time reference terminal 22 and the master clock of the measurement terminals 11a to 11c is:
Δf _MCLK = MCLK _GW × (1-SMCLK _IF / SMCLK _GW ) (Expression 1)
It can ask for. Note that GW indicates the time reference terminal 22, and IF indicates the measurement terminals 11a to 11c.

Note that each of the above clock frequencies is set in advance in the measurement terminals 11a to 11c. Alternatively, the above clock frequencies may be notified to the measurement terminals 11a to 11c in step S600.

(E) In step S650, the correction value calculation unit 510d calculates the correction value of the operation clock of the measurement terminals 11a to 11c from the above difference, and corrects the clock frequency by using the calculated correction value. As an example, the correction value γ is obtained by the following equation 2.

γ = Δf _MCLK / ACLK _GW (Expression 2)
Further, using the correction value γ, the corrected clock frequencies of the measurement terminals 11a to 11c are obtained by the following Equation 3.

MCLK _IF = (α + γ) × ACLK (Expression 3)

Here, as a specific example, the time reference terminal 22 and the measurement terminals 11a to 11c are common, and the initial setting is as follows: reference clock frequency = 32.768 kHz (kilohertz), α = 610, and β = 2. The respective reference clock frequencies in the time reference terminal 22 are set as ACLK _GW = 32.768 kHz, MCLK _GW = 20.021248 MHz (megahertz), and SMCLK _GW = 10.010624 MHz. The sub main clock frequency in the measurement terminals 11a to 11c is set as SMCLK _IF = 10.079278 MHz. In this case, the frequency difference (difference) of the master clock is calculated as Δf _MCLK = −137308 Hz from Equation 1, and the correction value γ is calculated as γ = −4 from Equation 2. Further, this correction value is substituted into Equation 3, and the corrected clock frequency is MCLK _IF = 606.

(F) In step S660, after the calculation of the correction value in step S650 is completed, the synchronization signal transmission unit 470b of the time reference terminal 22 in FIG. 8 transmits a synchronization signal to the measurement terminals 11a to 11c. On the other hand, in step S670, the synchronization signal transmission unit 510e of the measurement terminals 11a to 11c in FIG. 9 returns a synchronization signal to the time reference terminal 22. However, it is assumed that the synchronization signal transmission / reception timing is set in advance by the synchronization start time setting unit 440 so as to be a close time immediately before the measurement start time.

(G) In step S680, the communication time setting unit 470c of the time reference terminal 22 in FIG. 8 subtracts the half value obtained by subtracting the internal processing time of the measurement terminals 11a to 11c from the time required for transmission and reception of the synchronization signal in steps S660 and S670. Set to the communication time between the time reference terminal and the measurement terminal.

An example of the communication time setting process in the third embodiment will be described with reference to FIG. FIG. 14 shows a communication processing operation between the time reference terminal 22 and the measurement terminals 11a and 11b for synchronizing the measurement start time between the measurement terminals. For simplification of explanation, communication processing when only two measuring terminals are used will be described.

A rectangular portion (communication time (outward)) indicated by hatching in FIG. 14 indicates the time required for communication from the time reference terminal 22 to the measurement terminals 11a and 11b. White rectangular portions (internal processing) indicate the time required for internal processing in the measurement terminals 11a and 11b. A rectangular portion (communication time (recovery)) represented by a horizontal line indicates a time required for communication from the measurement terminals 11 a and 11 b to the time reference terminal 22. If the communication times between the measurement terminals 11a and 11b and the time reference terminal 22 are different, the operation start instruction from the time reference terminal 22 is delayed, so that the measurement start timing is shifted. Therefore, in this embodiment, the communication time difference (Δt in FIG. 14) between the measurement terminals 11a and 11b is calculated, and the measurement start timings of the measurement terminals 11a and 11b are individually set.

To measure the terminal 11a from time reference terminal 22, the synchronization signal is transmitted when the _{t 1,} the measuring terminal 11a receives this at _{t 2.} Then the internal processing is performed, the measuring terminal 11a sends back a synchronization signal to the time reference terminal 22 when t _3, time reference terminal 22 receives this at t _4. However, in another investigation terminal 11b, the communication started from t ₁ are transmitted synchronization signals at the timing of t _{1 'delayed} measurement terminal 11b, the partial communication start delay time and the communication time difference Delta] t, the delay from t ₂ The sync signal is received at the specified time. Thereafter, the same internal processing is performed, and the measurement terminal 11b returns a synchronization signal to the time reference terminal 22, and the time reference terminal 22 receives this at t ₄ ′.

For this reason, the one-way communication times t _IFa and t _IFb of the measurement terminals 11a and 11b are _given by the following equations.

Measurement terminal 11a: t _IFa = {(t ₄ -t ₁ )-(t ₃ -t ₂ )} / 2
Measurement terminal 11b: t _IFb = {(t ₄ '-t ₁ ')-(t ₃ -t ₂ )} / 2
At this time, the communication time difference Δt between the measurement terminals 11a and 11b is
Δt = t _IFb −t _IFa

(H) In step S690, the communication time setting unit 470c corrects the measurement start time based on the communication time difference. Specifically, the measurement start time of the measurement terminal 11b is set to be advanced or the measurement start time of the measurement terminal 11a is set to be delayed by the communication time difference Δt, and the measurement start time between the measurement terminals 11a and 11b is synchronized. .

For example, if the delay time of the measurement terminal 11a is 0 μs, the delay time of the measurement terminal 11b, that is, the communication time difference is 100 μs, and the remaining time is 10 seconds until the measurement start time, the measurement terminal 11a has 10s and the measurement terminal 11b has 10s− 100 μs is calculated as the corrected remaining time. In addition, the communication time setting unit 470c transmits the calculated remaining time to the remaining time setting unit 490 and prompts to set it as the remaining time.
(Example)
Below, the experiment of the measurement start time synchronization performed using two measurement terminals using the time synchronization system which concerns on 3rd embodiment of this invention, and its result are demonstrated. As a simple configuration of the time synchronization system, two computers were used: an operation control and data acquisition personal computer (hereinafter referred to as “PC”), one time reference terminal, and measurement terminals A and B. The time reference terminal and the measurement terminals A and B include an MCU. The PC and the time reference terminal are connected by wire, the distance between the time reference terminal and the measurement terminal A is 1.5 m (meters), the distance between the time reference terminal and the measurement terminal B is 0.5 m, and a specific low power wireless is between each Connected with. In order to measure the synchronization accuracy of the start times of the measurement terminals A and B and the time reference terminal, a reference signal was generated from the signal generator and input to the two measurement terminals A and B. The measurement start command was issued from the time reference terminal. The measurement start time was set individually for each target measurement terminal by shifting by the communication time difference between the two measurement terminals A and B calculated in advance.

As the measurement conditions, the reference signal input to the measurement terminals A and B was a frequency of 50 Hz, an amplitude of 1 V _pp (peak-to-peak voltage) square wave, and an offset of 1.65 V (volts) was given. The sampling frequency of measurement terminals A and B was 6 kHz. In addition, in order to confirm the correction effect of the MCU reference clock, the time synchronization accuracy was measured 10 times for each of two levels of whether or not the reference clock was corrected.

Before correction, the reference clock frequency of the time reference terminal was 10010624 Hz, the reference clock frequency of the measurement terminal A before correction was 10061864 Hz, and the reference clock frequency of the measurement terminal B before correction was 100007978 Hz. However, the corrected reference clock frequency of the measuring terminal A is 10012379 Hz, and the corrected reference clock frequency of the measuring terminal B is 10013184 Hz. The error from the reference clock of the time reference terminal after correction is 0.02% (percent) at the measurement terminal A (0.51% before correction) and 0.03% at the measurement terminal B (0.69% before correction). )Met.

15A and 15B show typical examples of reference signal waveforms acquired by the two measuring terminals A and B. FIG. FIG. 15A shows the result when the MCU reference clock is not corrected, and FIG. 15B shows the result when the MCU reference clock is corrected. The horizontal axis represents time, and the vertical axis represents voltage. In FIG. 15A, the rising edges of the pulse waveforms of measurement terminals A and B are shifted, and the pulse widths and waveforms of both are also shifted, but in FIG. 15B, the rising edges of the pulse waveforms of measurement terminals A and B are aligned and the pulse widths are also aligned. The waveforms are almost overlapping. From this result, it was found that when the MCU reference clock is corrected, the synchronization accuracy is improved as compared with the case where the MCU is not corrected.

As described above, according to the third embodiment of the present invention, the number of operation clocks for counting a predetermined time is corrected in the time reference terminal and each measurement terminal. In addition, determination processing based on the upper and lower thresholds is provided for the counter value to be calculated, and if it is outside the threshold, the number of flag transmissions is increased by one, thereby maintaining high clock accuracy with the minimum number of flag transmissions. As a result, power consumption associated with the synchronization processing can be reduced, and high-accuracy clock synchronization can be realized.
<Fourth embodiment>
FIG. 16 is a diagram illustrating a configuration of the time reference terminal 24 according to the fourth embodiment. The time reference terminal 24 is connected to at least one processing terminal (not shown in FIG. 16) that starts a predetermined process at a process start time that is a predetermined time. The time reference terminal 24 includes at least an operation start instruction unit 24a and a synchronization processing unit 24c.

The operation start instruction unit 24a transmits a signal instructing not to start processing until the processing start time to each processing terminal. The synchronization processing unit 24c corresponds to the clock accuracy related to the operation of each processing terminal in the time (period) from the current time to the processing start time when performing the synchronization processing with each of the processing terminals. The synchronization processing is completed for the time prior to the processing start time.

According to the fourth embodiment of the present invention, since the synchronization processing unit performs the synchronization processing based on the clock accuracy of each of the plurality of processing terminals, measurement errors due to fluctuations in the communication environment and measurement time intervals do not occur. As a result, high clock synchronization accuracy can be obtained. Furthermore, according to the present embodiment, since synchronization can be performed only once, power consumption can be suppressed low.
<Fifth embodiment>
FIG. 17 is a diagram illustrating the configuration of the processing terminals 12a to 12c according to the fifth embodiment. The processing terminals 12a to 12c are connected to a time reference terminal (not shown in FIG. 17) that instructs to start a predetermined process at a processing start time that is a predetermined time. The processing terminals 12a to 12c include at least a standby unit 12d, a synchronization processing unit 12e, and a processing unit 12f.

The standby unit 12d waits for the start of processing until the processing start time. The synchronization processing unit 12e performs synchronization processing with the time reference terminal at the synchronization start time notified from the time reference terminal. The processing unit 12f starts the processing at the processing start time.

According to the fifth embodiment of the present invention, the synchronization processing unit performs the synchronization processing at the time set by the time reference terminal based on the clock accuracy of the processing terminal. High synchronization accuracy can be obtained without generating a measurement error. Furthermore, according to the present embodiment, since synchronization can be performed only once, power consumption can be suppressed low.
<Sixth embodiment>
FIG. 18 is a diagram showing a configuration of the time synchronization system 4 in the sixth embodiment. The time synchronization system 4 includes the function of each part of the time reference terminal 24 described in the fourth embodiment and the function of each part of the processing terminals 12a to 12c described in the fifth embodiment.

According to the sixth embodiment, based on the clock accuracy of the processing terminals 12a to 12c, the mutual synchronization processing units (24c, 12e) perform the synchronization processing at the time set by the time reference terminal 24. In addition, the measurement time interval does not cause measurement errors, and high synchronization accuracy can be obtained.

A part or all of each of the above embodiments and modifications may be specified as in the following supplementary notes. However, each embodiment and each modification are not limited to the following description.
[Appendix 1]
A time reference terminal connected to at least one processing terminal that starts a predetermined process at a process start time that is a predetermined time;
An operation start instruction means for transmitting a signal instructing not to start the processing until the processing start time to each of the processing terminals;
Of the time from the current time to the processing start time, a time corresponding to the accuracy of the clock for each operation of the processing terminal is completed with each of the processing terminals so as to be completed prior to the processing start time. A time reference terminal comprising synchronization processing means for performing synchronization processing.
[Appendix 2]
Clock accuracy measuring means for measuring the accuracy of the clock at each of the processing terminals;
The synchronization processing means is configured so that each of the processing terminals completes prior to the processing start time by a time corresponding to the accuracy of the actually measured clock among the time from the current time to the processing start time. Carrying out the synchronization process between
The time reference terminal according to attachment 1.
[Appendix 3]
When there are a plurality of the processing terminals,
Based on the completion time of the synchronization process, a communication time with the time reference terminal for each of the processing terminals is calculated, and a communication time of a certain processing terminal and a communication time with another processing terminal among the plurality of processing terminals. Communication time setting means for correcting the measurement start time of each of the certain processing terminal and the other processing terminal based on the calculated difference.
The time reference terminal according to

appendix

1 or 2.
[Appendix 4]
A processing terminal connected to a time reference terminal for instructing to start a predetermined process at a processing start time that is a predetermined time;
Standby means for waiting for the start of the process until the process start time;
Synchronization processing means for performing synchronization processing with the time reference terminal at the synchronization start time notified from the time reference terminal;
A processing terminal comprising processing means for starting the processing at the processing start time.
[Appendix 5]
The synchronization processing means includes
At least one or more flags are received from the time reference terminal at regular time intervals, clock pulses generated between the received flags are counted, and an average value of the count values between the flags is calculated. An average value calculating means;
Determining means for determining whether the average value is within a predetermined threshold range;
If the result of the determination is within a threshold range, a difference calculating means for calculating a difference between the counter value of the clock pulse generated between each of the flags measured by the time reference terminal and the average value;
The processing terminal according to appendix 4, further comprising: a correction value calculating unit that calculates a correction value of a clock related to the operation of the terminal based on the difference and corrects a clock frequency of the terminal based on the correction value.
[Appendix 6]
A time reference terminal according to any one of appendices 1 to 3, and the processing terminal;
The processing terminal includes the processing terminal described in

Appendix

4 or 5.
Time synchronization system.
[Appendix 7]
The time reference terminal further comprises flag transmission means for transmitting a flag at a fixed time interval to each of the processing terminals,
The flag transmission means transmits the flag again if the determination result is outside the range of the threshold value,
The processing terminal is the processing terminal described in Appendix 5, and the difference calculation means calculates the average value from each count value including between the retransmitted flag and the previously transmitted flag. To
The time synchronization system according to appendix 6.
[Appendix 8]
A time synchronization method performed by a time reference terminal connected to at least one processing terminal that starts predetermined processing at a processing start time that is a predetermined time,
A signal indicating that the processing is not started until the processing start time is transmitted to each of the processing terminals;
Of the time from the current time to the processing start time, a time corresponding to the accuracy of the clock for each operation of the processing terminal is completed with each of the processing terminals so as to be completed prior to the processing start time. Comprising performing synchronous processing;
Time synchronization method.
[Appendix 9]
Further comprising measuring the accuracy of the clock at each of the processing terminals;
Each of the processing terminals is configured to complete the synchronization processing prior to the processing start time for a time corresponding to the accuracy of the actually measured clock among the time from the current time to the processing start time. The synchronization process is performed with
The time synchronization method according to attachment 8.
[Appendix 10]
When there are a plurality of the processing terminals,
Based on the completion time of the synchronization process, a communication time with the time reference terminal for each of the processing terminals is calculated, and a communication time of a certain processing terminal and a communication time with another processing terminal among the plurality of processing terminals. Further comprising correcting the measurement start times of the certain processing terminal and the other processing terminal based on the calculated difference,
The time synchronization method according to appendix 8 or 9.
[Appendix 11]
A time synchronization method performed by at least one processing terminal connected to a time reference terminal instructing to start a predetermined process at a processing start time that is a predetermined time,
Wait for the start of the process until the process start time,
At the synchronization start time notified from the time reference terminal, perform the synchronization process with the time reference terminal,
Starting the process at the process start time,
Time synchronization method.
[Appendix 12]
Performing the synchronization process includes
Receive at least one or more flags from the time reference terminal at regular time intervals, count clock pulses generated between the received flags, and calculate an average value of the count values between the flags. ,
Determining whether the average value is within a predetermined threshold;
If the result of the determination is within the threshold range, the difference between the counter value of the clock pulse generated between each of the flags measured by the time reference terminal and the average value is calculated.
Calculating a correction value of a clock related to the operation of the terminal based on the difference, and correcting the clock frequency of the terminal based on the correction value;
The time synchronization method according to claim 11, further comprising:
[Appendix 13]
A time synchronization method performed by the time reference terminal according to any one of appendices 8 to 10,
A time synchronization method comprising the time synchronization method performed by the processing terminal described in Appendix 11 or 12.
[Appendix 14]
The time reference terminal further includes transmitting a flag to each of the processing terminals at regular time intervals,
If the transmission of the flag is outside the range of the threshold value of the determination, the flag is transmitted again,
The calculation of the difference by the processing terminal is to calculate the average value from each count value including between the flag transmitted again and the flag transmitted last time.
The time synchronization method according to attachment 13.

The present invention has been described above using the above-described embodiment as an exemplary example. However, the present invention is not limited to the above-described embodiment. That is, the present invention can apply various modes that can be understood by those skilled in the art within the scope of the present invention.

This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2014-067363 for which it applied on March 28, 2014, and takes in those the indications of all here.

1

Time synchronization system

20, 21, 22

Time reference terminal

10a, 10b, 10c, 11a, 11b,

11c Measurement terminal

100, 300, 400 Measurement start

time setting unit

110, 310, 410 Measurement

interval calculation unit

120, 320, 420 Clock

Accuracy storage unit

130, 330, 430 Maximum error

time calculation unit

140, 340, 440 Synchronization start

time setting unit

150, 350, 450 Operation

start instruction unit

160, 360, 460 Transmission /

reception unit

170, 370, 470

Synchronization processing unit

180, 380 480 Measurement start

time storage unit

190, 490 Remaining time setting unit 390 Correction remaining

time setting unit

200, 500

Measurement standby unit

210, 510

Synchronization processing unit

220, 520

Measurement processing unit

230, 530 Transmission /

reception unit

240, 540 Synchronization start

time storage Part

250, 550 When remaining Storage unit

Claims

A time reference terminal connected to at least one processing terminal that starts a predetermined process at a process start time that is a predetermined time;
An operation start instruction means for transmitting a signal instructing not to start the processing until the processing start time to each of the processing terminals;
Of the time from the current time to the processing start time, a time corresponding to the accuracy of the clock for each operation of the processing terminal is completed with each of the processing terminals so as to be completed prior to the processing start time. A time reference terminal comprising synchronization processing means for performing synchronization processing.
Clock accuracy measuring means for measuring the accuracy of the clock at each of the processing terminals;
The synchronization processing means is configured so that each of the processing terminals completes prior to the processing start time by a time corresponding to the accuracy of the actually measured clock among the time from the current time to the processing start time. Carrying out the synchronization process between
The time reference terminal according to claim 1.
When there are a plurality of the processing terminals,
Based on the completion time of the synchronization process, a communication time with the time reference terminal for each of the processing terminals is calculated, and a communication time of a certain processing terminal and a communication time with another processing terminal among the plurality of processing terminals. Communication time setting means for correcting the measurement start time of each of the certain processing terminal and the other processing terminal based on the calculated difference.
The time reference terminal according to claim 1 or 2.
A processing terminal connected to a time reference terminal for instructing to start a predetermined process at a processing start time that is a predetermined time;
Standby means for waiting for the start of the process until the process start time;
Synchronization processing means for performing synchronization processing with the time reference terminal at the synchronization start time notified from the time reference terminal;
A processing terminal comprising processing means for starting the processing at the processing start time.
The synchronization processing means includes
At least one or more flags are received from the time reference terminal at regular time intervals, clock pulses generated between the received flags are counted, and an average value of the count values between the flags is calculated. An average value calculating means;
Determining means for determining whether the average value is within a predetermined threshold range;
If the result of the determination is within a threshold range, a difference calculating means for calculating a difference between the counter value of the clock pulse generated between each of the flags measured by the time reference terminal and the average value;
5. The processing terminal according to claim 4, further comprising: a correction value calculating unit that calculates a correction value of a clock related to the operation of the terminal based on the difference, and corrects a clock frequency of the terminal based on the correction value. .
A time reference terminal according to any one of claims 1 to 3, and the processing terminal,
The processing terminal includes the processing terminal according to claim 4 or 5.
Time synchronization system.
The time reference terminal further comprises flag transmission means for transmitting a flag at a fixed time interval to each of the processing terminals,
The flag transmission means transmits the flag again if the determination result is outside the range of the threshold value,
The processing terminal is a processing terminal according to claim 5, wherein the difference calculation means calculates the average value from each count value including between the flag transmitted again and the flag transmitted last time. calculate,
The time synchronization system according to claim 6.
A time synchronization method performed by a time reference terminal connected to at least one processing terminal that starts predetermined processing at a processing start time that is a predetermined time,
A signal indicating that the processing is not started until the processing start time is transmitted to each of the processing terminals;
Of the time from the current time to the processing start time, a time corresponding to the accuracy of the clock for each operation of the processing terminal is completed with each of the processing terminals so as to be completed prior to the processing start time. Comprising performing synchronous processing;
Time synchronization method.
Further comprising measuring the accuracy of the clock at each of the processing terminals;
Each of the processing terminals is configured to complete the synchronization processing prior to the processing start time for a time corresponding to the accuracy of the actually measured clock among the time from the current time to the processing start time. The synchronization process is performed with
The time synchronization method according to claim 8.
A time synchronization method performed by at least one processing terminal connected to a time reference terminal instructing to start a predetermined process at a processing start time that is a predetermined time,
Wait for the start of the process until the process start time,
At the synchronization start time notified from the time reference terminal, perform the synchronization process with the time reference terminal,
Starting the process at the process start time,
Time synchronization method.