JP2016057169A - Method for comparing time of clocks and method for correcting time of clock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for comparing time of clocks that accurately and reliably obtain time difference between two comparison object clocks.SOLUTION: A first time comparison information acquisition device and a second time comparison information acquisition device connected with a time comparison object first reference clock and second reference clock, respectively, mutually perform data communication with an opposite station when respective internal clocks reach comparison start time t, tdesignated by a time management server, and transmits time t, twhen data was received from the opposite station to the time management server. Because the time difference Δtbetween the first reference clock and the second reference clock has the relation of Δt=(Δt-Δt)/2 with a propagation delay time Δtat the first time comparison information acquisition device and a propagation delay time Δtat the second time comparison information acquisition device, the time of the first and second reference clocks can be highly-accurately compared.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a clock time comparison method for comparing the time difference between two comparison watches placed at locations where radio waves can reach each other, and the time of each comparison watch is corrected based on the time comparison result. The present invention relates to a time correction method for a clock.

  Conventionally, a time synchronization method using GPS has been used as a method for easily synchronizing clocks. Since the time synchronization by GPS is low in accuracy, a method using an optical fiber (requires a dedicated line) is known as a time synchronization method when accuracy higher than GPS is required. Although the time synchronization by this optical fiber is extremely accurate, the capital investment is large and the versatility is lacking.

  Therefore, as a method of simply synchronizing the time between the two stations, the master node and the slave node, which are two stations on the ground, the clocks of both clocks are compared by performing bidirectional wireless communication between the master node and the slave node. A device that corrects the time of a slave node from the difference has been proposed (see, for example, Patent Document 1).

  In the invention described in Patent Document 1, a communication packet is transmitted from a slave node to a master node, a response signal is transmitted from the master node to the slave node in response to this reception, and a time until the slave node receives this response signal (slave The time from the transmission time to the reception time at the node) is the round trip propagation delay time due to data communication between the master node and the slave node, and the response time from when the master node receives the packet until it transmits the response signal Therefore, if the response time known at the master node is subtracted from the round trip time between the slave node and the master node and divided by 2, the calculated propagation delay time can be obtained. From the difference between the propagation delay time measured by the watch and the calculated propagation delay time, It is possible to determine the time difference between the clocks of de watch and slave node, it is possible time synchronization master node and the slave node.

  As described above, in the invention described in Patent Document 1, it is considered that time synchronization is much more accurate than time synchronization using GPS and cost is much lower than time synchronization using an optical fiber. It is done.

JP 2014-115794 A

  However, in the invention described in Patent Document 1, the time difference communication is alternately performed between the slave node and the master node, and when communicating from the slave node to the master node and when communicating from the master node to the slave node. Therefore, there is a possibility that the propagation state in the propagation path between both nodes has changed, and there is a possibility that a non-negligible error may be mixed in the propagation delay time in the forward path and the propagation delay time in the backward path. For this reason, it cannot be said that accurate time comparison can be performed reliably. If the time difference between the clock of the master node and the clock of the slave node cannot be acquired with high accuracy, the time correction of the slave node cannot be performed with high accuracy.

  Accordingly, an object of the present invention is to provide a time comparison method for a timepiece and a time correction method for a timepiece that can accurately and reliably acquire the time difference between two timepieces to be compared.

In order to solve the above-mentioned problem, a time comparison method for a clock according to claim 1 is a comparison in which a comparison start time t ₀ is set in advance in two wireless communication stations that can start communication in synchronization with the time of a comparison clock. A start time setting step, a code transmission step of mutually transmitting codes from each station to another station when the time of the comparison clock corresponding to each wireless communication station reaches the comparison start time t ₀ , and each communication station Based on the propagation delay time measuring step for measuring the propagation delay time Δt from when the code is transmitted to the station until the code is received from the other station, and two propagation delay times Δt measured at both communication stations, 2 And a time difference obtaining step for obtaining a time difference Δt _difference between two comparison watches.

  Further, the invention according to claim 2 is the time comparison method of the timepiece according to claim 1, wherein, in the code transmission step, the code of the own station set in advance is modulated with a predetermined time signal to generate a modulation signal. A first process of generating and a second process of converting the modulated signal into a phase and transmitting the modulated signal, and in the propagation delay time measuring step, the modulated signal received from the other station and the code used by the other station A third process for performing a correlation process with a replica signal generated by modulating a time signal of the local station, a fourth process for obtaining a group delay and a phase delay by the correlation process, and obtaining a highly accurate propagation delay time Δt, , Including.

A time correction method for a timepiece according to claim 3 corresponds to a master station corresponding to a highly reliable timepiece and a timepiece with low reliability based on the time comparison method of the timepiece according to claim 1 or claim 2. A time difference Δt _difference relative to the slave station is acquired, and the time of the clock corresponding to the slave station is corrected using the time difference Δt _difference as time correction information.

A time correction method for a timepiece according to claim 4 is based on the time comparison method for timepieces according to claim 1 or 2, and is a reference timepiece composed of three or more comparison timepieces for which a reference time is to be calculated. Based on an arbitrary reference time calculation method that acquires the time difference Δt _difference between two stations in a combination that can specify the relative time difference of all clocks in the group, and uses the relative time difference of each clock. The reference time in the reference clock group is calculated, the difference between the time of the time correction target clock and the reference time is obtained as time correction information Δt _correct , and the time correction target clock is calculated based on the time correction information Δt _correct. The time is corrected.

The invention according to claim 5 is the time correction method for a timepiece according to claim 4, wherein the communication station corresponding to the reference clock belonging to the reference clock group is a master station and the clock does not belong to the reference clock group. The corresponding communication station is a slave station, the relative time difference Δt _difference between the master station and the slave station is acquired, and the time of the clock corresponding to the slave station is corrected using the time difference Δt _difference as a correction amount. It is characterized by.

According to a sixth aspect of the invention, in the time correction method for a timepiece according to the fifth aspect, the time correction information Δt _correct of the master station is added to the relative time difference Δt _difference between the master station and the slave station. The correction amount is used, and the time of the clock corresponding to the slave station is corrected.

According to the clock time comparison method of the present invention, data communication to other stations is performed at the timing when the comparison clock of each communication station reaches the same time (comparison start time t ₀ ). Communication to the other station is performed through the propagation path, and the propagation delay time from each station to the other station can be regarded as almost the same. Based on the two propagation delay times Δt measured at both communication stations The time difference Δt _difference between the two obtained comparison watches is highly accurate. In addition, even when both communication stations or one communication station moves and the relative distance between the two communication stations changes, the time difference Δt _difference between the two comparison watches can be obtained with high accuracy. There is. According to the time correction method of the timepiece performed using the time difference Δt _difference with high accuracy obtained by the time comparison method according to the present invention, highly accurate time correction can be realized.

1 is a schematic configuration diagram of a communication system to which a time comparison method and a time correction method of a timepiece according to the present invention can be applied. It is a functional block diagram which shows schematic structure of a time comparison information acquisition apparatus. It is the sequence diagram which showed an example of the communication process for the time comparison and time correction which are performed in the communication system which concerns on this embodiment in time series. It is an outline explanatory view in the case of obtaining a reference time as a deviation average of time differences between reference stations A to D.

  Next, an embodiment of a communication system to which a time comparison method and a time correction method according to the present invention are applied will be described with reference to the accompanying drawings.

  In the communication system shown in FIG. 1, a first time comparison information acquisition device 1a, a second time comparison information acquisition device 1b, a third time comparison information acquisition device 1c, and a fourth device having communication functions capable of two-way wireless communication with each other. The time comparison information acquisition device 1d is connected to the first reference clock 3a, the second reference clock 3b, the third reference clock 3c, and the fourth reference clock 3d through the local cables 2, respectively. The first to fourth reference clocks 3a to 3d belong to a reference clock group including three or more comparative clocks with high accuracy, and are a clock group for which a reference time to be described later is calculated. The reference clock group is not limited to extremely high-precision clocks such as cesium atomic clocks, strontium optical lattice clocks, and ytterbium optical lattice clocks. It doesn't matter.

  The first to fourth reference clocks 3a to 3d belonging to the reference clock group are fixed to indoor equipment such as reinforced concrete because of their structure, and the vicinity of the first to fourth reference clocks 3a to 3d has a good radio wave environment. However, the first to fourth time comparison information acquisition devices 1a to 1d are installed outdoors with a good view, or only the antenna portions of the first to fourth time comparison information acquisition devices 1a to 1d are outdoors. It is desirable to install it. In this communication system, as will be described later, two-way communication for time comparison between the first time information acquisition device 1a and the second time information acquisition device 1b, and the second time information acquisition device 1b and the third time information acquisition. It is only necessary to be able to perform bidirectional communication for time comparison in the device 1c and bidirectional communication for time comparison in the third time information acquisition device 1c and the fourth time information acquisition device 1d. Because of this, bidirectional communication may not be possible with other combinations.

  The first to fourth time comparison information acquisition devices 1 a to 1 d are connected to the time management server 4 via the wired network 5. The wired network 5 may be constituted by a dedicated line or a public communication network such as the Internet. When the time management server 4 and the first to fourth time comparison information acquisition devices 1a to 1d are present in an area where good wireless communication is possible, the time management server 4 and the first to fourth time comparisons in the wireless communication network. The information acquisition apparatuses 1a to 1d may be connected.

  Furthermore, in this communication system, the fifth time comparison information acquisition device 1s is connected to the low-precision slave clock 6 that does not belong to the reference clock group via the local cable 2, and the first time in the area where wireless communication is possible. The comparison information acquisition device 1a and the fifth time comparison information acquisition device 1s can perform bidirectional communication for time comparison. The fifth time comparison information acquisition device 1s may also be connected to the wired network 5 so as to be able to perform wired communication with the first time comparison information acquisition device 1a via the wired network 5, but the slave clock 6 is portable. If there is no environment for connecting the fifth time comparison information acquisition device 1s to the wired network 5 before the slave clock 6 is moved, the first to first communication environments are the best. There is a merit that bi-directional communication for time comparison can be realized by selecting the 4-time comparison information acquisition devices 1a to 1d.

  The above-described first to fourth time comparison information acquisition devices 1a to 1d (when not distinguished, simply referred to as the time comparison information acquisition device 1) are the first to fourth reference clocks 3a to 3d (when not distinguished from each other, simply the reference). 2 is a wireless communication station that obtains information for obtaining a relative time difference between the timepiece 3 and a schematic configuration thereof.

  The time comparison information acquisition device 1 receives the transmission of the 10 MHz signal and the 1PPS signal from the reference clock 3, and measures the time synchronized with the reference clock 3 by the internal clock 11, and the time information of the internal clock 11 is received time acquisition means. 12 and time comparison operation start control means 13.

On the other hand, the time management server 4 selects two reference clocks 3 for time comparison, sets a time for starting the time comparison operation (comparison start time), and sets each of the two reference clocks 3 to be compared with each other. Since the instruction is transmitted to the connected time comparison information acquisition apparatus 1 via the wired network 5, the time comparison information acquisition apparatus 1 receives the instruction from the time management server 4 by the wired communication processing means 14, The ID information of the partner station to be compared and the instructed comparison start time t ₀ are supplied to the time comparison operation start control means 13.

The time comparison operation start control means 13 having received the information for time comparison, when the time of the internal clock 11 reaches the comparison start time t ₀ , the transmission code stored in the transmission code storage means 15 (for example, its own station). A unique identification number or the like is supplied to the wireless communication processing means 16, and a data packet for time comparison is generated by the wireless communication processing means 16 and emitted from the transmission / reception antenna 17.

As described above, when one of the time comparison information acquisition devices 1 reaches the comparison start time t ₀ counted by the internal clock 11 and transmits a code to the other station subject to time comparison, the other time comparison information acquisition device 1 Since the code is transmitted almost at the same time (comparison start time t ₀ measured by the internal clock 11 in the other station), the wireless communication processing means 16 is transmitted via the transmission / reception antenna 17 after the required propagation delay time has elapsed. Will receive codes from other stations.

The reception time acquisition means 12 notified of the code reception from the other station by the wireless communication processing means 16 determines the reception time t _receive from the time of the internal clock 11 at the timing, and this reception time t _receive is the wired communication processing means. 14 to the time management server 4 via the wired network 5.

Then, in the time management server 4 that has received the reception time t _receive transmitted from each of the two time comparison information acquisition devices 1 selected in advance, based on this, the reference connected to each of the two time comparison information acquisition devices 1 A time difference Δt _difference occurring in the timepiece 3 can be calculated.

  Here, a specific example of time comparison in which the time comparison between the first time comparison information acquisition device 1a and the second time comparison information acquisition device 1b is performed by the overall control of the time management server 4 will be described in time series based on FIG. To do.

As two reference clocks to be time comparison, the first reference clock 3a, selects a second reference clock 3b, to determine the comparison start time t ₀ (or entered the time comparison control command by external operation) The time management server 4 starts comparing the first time comparison information acquisition device 1a corresponding to the first reference clock 3a and the second time comparison information acquisition device 1b corresponding to the second reference clock 3b via the wired network 5. The time t ₀ and destination information are notified. Although omitted in FIG. 3, the first and second time comparison information acquisition devices 1 a and 1 b that have received an instruction from the time management server 4 return acceptance or rejection to the time management server 4. Including the step of adjusting the start or postponement of the time comparison, and when the comparison start time t ₀ is reached, the first and second time comparison information acquisition devices 1a and 1b are adjusted so as to perform code transmission for time comparison. Keep it.

As described above, the first and second time comparison information acquisition devices 1a and 1b instructed by the time management server 4 to perform the time comparison operation are the times of the internal clocks 11 (in effect, the first and second reference values). When the clocks 3a and 3b) reach the comparison start time t ₀ , code transmission to other stations is started.

For example, when the time of the second reference clock 3b is ahead of the time of the first reference clock 3a, first, the comparison start time t _{0 (b)} in the internal clock 11 of the second time comparison information acquisition device 1b is reached. At the timing, the code transmission is started from the second time comparison information acquisition device 1b to the first time comparison information acquisition device 1a, and the second time comparison information 1b is delayed by the time difference Δt _difference between the first reference timepiece 1a and the second reference timepiece 1b. Code transmission starts from the first time comparison information acquisition device 1a to the second time comparison information acquisition device 1b at the timing when the comparison start time t _{0 (a)} in the internal clock 11 of the one time comparison information acquisition device 1a is reached. Is done.

Then, after code transmission is started from the second time comparison information acquisition device 1b toward the first time comparison information acquisition device 1a, the distance between the first time comparison information acquisition device 1a and the second time comparison information acquisition device 1b is increased. When the propagation delay time Δt _{delay (ab)} determined according to the distance and the state of the propagation path elapses, the second time comparison is performed at the reception time t _{receive (a)} in the internal clock 11 of the first time comparison information acquisition device 1a. The code from the information acquisition device 1b is received. When this reception time t _{receive (a)} is transmitted to the time management server 4, the time management server 4 uses the “reception time t _{receive (a) −comparison} start time t ₀ ” to make the appearance in the first time comparison information acquisition device 1a appear. The upper propagation delay time Δt _(a) can be obtained. Note that the propagation delay time Δt _(a) may be transmitted from the first time comparison information acquisition device 1 _a to the time management server 4. The true propagation delay time Δt _{delay (ab)} from the first time comparison information acquisition device 1a to the second time comparison information acquisition device 1b and the apparent propagation delay time Δt _{(a) in} the first time comparison information acquisition device 1a The relationship is as shown in Equation (1).

Δt _(a) = Δt _{delay (ab)} −Δt _difference (1)

On the other hand, the code transmitted from the first time comparison information acquisition device 1a with a time difference Δt _difference delayed from the timing at which the second time comparison information acquisition device 1b transmits the code at the comparison start time t _{0 (b)} is: A propagation delay time Δt _{delay (ba)} determined according to the separation distance between the first time comparison information acquisition device 1a and the second time comparison information acquisition device 1b and the state of the propagation path has elapsed, and the first time comparison information acquisition device 1a. when the reception time t _{receive (a)} receiving time delayed by the time difference Delta] t _difference than t _{receive (b),} and thus reaching the second time comparison information acquisition device 1b. When this reception time t _{receive (b)} is transmitted to the time management server 4, the time management server 4 uses the “reception time t _{receive (b) −comparison} start time t ₀ ” to make the appearance in the second time comparison information acquisition apparatus 1 b appear. The upper propagation delay time Δt _(b) can be obtained. Note that the propagation delay time Δt _(b) may be transmitted from the second time comparison information acquisition device 1b to the time management server 4. The true propagation delay time Δt _{delay (ba)} from the second time comparison information acquisition device 1b to the first time comparison information acquisition device 1a and the apparent propagation delay time Δt _{(b) in} the second time comparison information acquisition device 1b The relationship is as shown in Equation (2).

Δt _(b) = Δt _{delay (ba)} + Δt _difference (2)

Here, de compared to start time t _{0 (b)} in comparison start time t _{0 (a)} and the second time comparison information acquisition device 1b at the first time comparison information acquisition apparatus 1a, the transmission time difference between the time only difference Delta] t _difference is Although the time system of the reference clocks 3a to 3e belonging to the reference clock group is at a high level, the time difference Δt _difference is very small, and the first time comparison information acquisition device 1a and the second time comparison information acquisition It can be considered that the propagation state in the propagation path between the first time comparison information acquisition device 1a and the second time comparison information acquisition device 1b is the same until the transmission / reception with the device 1b is completed. Therefore, the transmission delay time Δt _{delay (ab)} until the code transmitted from the first time comparison information acquisition device 1a reaches the second time comparison information acquisition device 1b, and conversely, the code transmitted from the second time comparison information acquisition device 1b. Since the propagation delay time Δt _{delay (ba)} until the code reaches the first time comparison information acquisition device 1a can be handled as a completely equal value, “Δt _{delay (ab)} = Δt _{delay (ba)} ” is expressed by the above equation (1). , (2) is solved, the time difference Δt _difference between the first reference clock 3a and the second reference clock 3b is obtained by equation (3).

Δt _difference = (Δt _(b) −Δt _(a) ) / 2 Equation (3)

As described above, the first reference clock 3a is obtained by the first time comparison information acquisition device 1a and the second time comparison information acquisition device 1b, which are two wireless communication stations connected to the time management server 4 via the wired network T5. In the communication system for obtaining the time difference Δt _difference between the first reference clock 3b and the second reference clock 3b, the comparison start time setting in which the comparison start time t ₀ is set in advance in two radio communication stations that can start communication in synchronization with the time of the comparison clock And a code transmission step for mutually transmitting codes from each station to another station when the time of the comparison clock corresponding to each wireless communication station reaches the comparison start time t ₀ , and each communication station transmits a code to the other station Based on the propagation delay time measuring step for measuring the propagation delay time Δt from transmission to reception of a code from another station, and two comparison delays based on the two propagation delay times Δt measured at both communication stations Watch A time difference obtaining step of obtaining the time difference Delta] t _difference, it can be realized the time comparison process watches made of.

According to the clock time comparison method of the present invention, data communication to other stations is performed at the timing when the comparison clocks of the communication stations reach the same time (comparison start time t ₀ ). Communication to the other station is performed through the propagation path of the condition, and the propagation delay time from each station to the other station can be regarded as almost the same, and the two propagation delay times Δt measured at both communication stations The time difference Δt _difference between the two comparison watches obtained based on the above becomes highly accurate. Further, even when both communication stations or one communication station moves and the relative distance between both communication stations changes, the propagation delay time Δt _delay can be regarded as the same, and the error factor Therefore, there is an advantage that the time difference Δt _difference between the two comparison watches can be obtained with high accuracy.

In the time management server 4 in which the time difference Δt _difference between the first reference clock 3a and the second reference clock 3b that have performed the time comparison operation as described above is obtained, the reference time is calculated using this. The method for calculating the reference time is not particularly limited, but FIG. 4 shows a case where the reference time t _correct is calculated from an equally weighted average of all the reference clocks belonging to the reference clock group. Here, for simplicity of explanation, the time of the first reference clock 3a is the latest, followed by the time of the second reference clock 3b and the time of the third reference clock 3c, and the time of the fourth reference clock 3b is the most. Let's be quick.

In order to obtain an equally weighted average of the first to fourth reference clocks 3a, for example, the time of the first reference clock 3a is set to 0 (the time difference from the first reference clock 3a is 0). What is necessary is just to obtain | require the average of each time difference of 3a and other 2nd-4th reference | standard timepieces 3b-3d. That is, Motoma' average of the time difference between the first reference clock 3a and other second to fourth reference clock 3b~3d, the correction information Δt for the time of the first reference clock 3a to the reference time t _{correct Since} it is _{correct (a)} , the reference time t _correct is obtained as the time obtained by correcting the time of the first reference clock 1a with the correction information Δt _{correct (a)} .

Specifically, the time difference between the first reference clock 1a and the second reference clock 3b is Δt _{difference (a, b)} , and the time difference between the first reference clock 1a and the third reference clock 3c is Δt _{difference (a, b c) When} the time difference between the first reference clock 1a and the fourth reference clock 3d is Δt _{difference (a, d)} , “Δt _{correct (a)} = (Δt _{difference (a, b)} + Δt _{difference (a, c) )} + Δt _{difference (a, d)} ) / 4 ”, the correction information Δt _{correct (a)} of the first reference clock 1a is obtained, and the time earlier than the first reference clock 3a by Δt _{correct (a)} is the reference time t _correct . Become.

Then, the time correction information Δt _{correct (b)} which is the difference between the time of the second reference clock 3b and the reference time t _correct is obtained by “Δt _{correct (a)} −Δt _{difference (a, b)} ”, and the third reference clock The time correction information Δt _{correct (c)} that is the difference between the time 3c and the reference time t _correct is obtained by “Δt _{correct (a)} −Δt _{difference (a, c)} ”, and the time of the fourth reference clock 3d and the reference time The time correction information Δt _{correct (d)} which is the difference from t _correct is obtained by “Δt _{difference (a, d)} −Δt _{correct (a)} ”. The time difference Δt _{difference (a, c)} between the first reference clock 3a and the third reference clock 3c is “Δt _{difference (a, b)} + Δt _{difference (b, c)} ”, which is _{different from} that of the first reference clock 3a. The time difference Δt _{difference (a, d)} from the fourth reference clock 3d is “Δt _{difference (a, b)} + Δt _{difference (b, c)} + Δt _{difference (c, d)} ”.

The time correction information Δt _{correct (b)} , Δt _{correct (c)} , Δt _{correct (d)} , which is the difference between the time of the second to fourth reference clocks 3 _{b to 3 d} and the reference time t _correct , Even if the time of each of the four reference clocks 3b to 3d is set to 0, the same value is obtained from the average of the time differences from the other reference clocks. Each of the first to fourth reference clocks 3a to 3d belonging to the reference clock group is a clock group in which a constant accuracy is ensured, and among them, a clock with high accuracy reliability and a clock with relatively low reliability. In some cases, the time management server 4 has weighting information determined based on the reliability for the first to fourth reference clocks 3a to 3d, and the weighting information is added to the reference time. May be determined. For example, if the weighting information of the first reference clock 3a is Wa, the weighting information of the second reference clock 3b is Wb, the weighting information of the third reference clock 3c is Wc, and the weighting information of the fourth reference clock 3d is Wd, the first The correction information Δt _{correct (a)} for setting the time of the reference clock 3a as the reference time is “Δt _{correct (a)} = (Wb × Δt _{difference (a, b)} + Wc × Δt _{difference (a, c)} + Wd × Δt _{difference (a, d)} ) / (Wa + Wb + Wc + Wd) ".

Time correction information Delta] t _correct obtained as described above is not necessarily so it is not necessary to use the correction of reference clock 3, the first through fourth reference each clock 3a~3d time correction information Δt _{correct (a)} ~Δt _{correct Although} it is not necessary for the time management server 4 to have a function of transmitting _(d) to the first to fourth time comparison information acquisition devices 1a to 1d, for example, a time correction information request is acquired for the first time comparison information acquisition. When the device 1 has transmitted, the time management server 4 may have a function of returning time correction information Δt _{correct (a)} of the first reference clock 1a corresponding thereto.

The above is “acquiring each time difference Δt _difference between two stations in a reference clock group composed of three or more comparative clocks that are subject to reference time calculation in a combination that can specify the relative time difference of all clocks. The reference time within the reference clock group is calculated based on an arbitrary reference time calculation method that uses the relative time difference of each clock, and the time difference between the time of the time correction target clock and the reference time is corrected. determined as the information Delta] t _correct, based on the time correction information Delta] t _correct, the time correction method "watch for correcting the time of the clock of the time correction target has been realized in the communication system of the configuration of FIG. 1, less accurate slave clock 6 can also be applied to a time correction method in which 6 is corrected with the time of the reference clock 3 with high accuracy.

  For example, the fifth time comparison information acquisition device 1s corresponding to the low-accuracy slave clock 6 that does not belong to the reference clock group has a time relative to the first to fourth time comparison information acquisition devices 1a to 1d in the communicable range. A function for making a time comparison request for correction is provided, and the first to fourth time comparison information acquisition devices 1a to 1a that accept the time comparison operation in response to the time comparison request from the fifth time comparison information acquisition device 1s. A time comparison operation is performed with any one of 1d, and the time of the slave clock 6 is set to the time of the reference clock 1. In the example shown in FIG. 3, the first time comparison information acquisition device 1a functions as a master station, and the fifth time comparison information acquisition device 1s functions as a slave station.

First, when a time comparison request is transmitted by wireless communication from the fifth time comparison information acquisition device 1s to the first time comparison information acquisition device 1a, the comparison start time t ₀ is passed through prior adjustment between both stations (not shown). Is determined. In other words, the fifth time comparison information acquisition device 1s is provided with a function for indicating the comparison start time in the time management server 4, so that the fifth time comparison information acquisition device 1s, the first time comparison information acquisition device 1a, The time comparison operation can be executed between the two. As will be described later, the fifth time comparison information acquisition device 1s also has a function for obtaining time correction information Δt _correct .

For example, when the time of the slave clock 6 is ahead of the time of the first reference clock 3a, first, at the timing when the comparison start time t _{0 (s)} in the internal clock 11 of the fifth time comparison information acquisition device 1s is reached. The code transmission is started from the fifth time comparison information acquisition device 1s to the first time comparison information acquisition device 1a, and the first time comparison information is delayed by the time difference Δt _difference between the first reference clock 1a and the slave clock 6. Code transmission is started from the first time comparison information acquisition device 1a to the fifth time comparison information acquisition device 1s at the timing when the comparison start time t _{0 (a)} in the internal clock 11 of the acquisition device 1a is reached.

Then, after the code transmission is started from the fifth time comparison information acquisition device 1s toward the first time comparison information acquisition device 1a, the first time comparison information acquisition device 1a and the fifth time comparison information acquisition device 1s are separated from each other. When the propagation delay time Δt _{delay (sa)} determined according to the distance and the state of the propagation path elapses, the fifth time comparison is performed at the reception time t _{receive (a)} in the internal clock 11 of the first time comparison information acquisition device 1a. The code from the information acquisition device 1s is received. The first time comparison information acquisition device 1a uses the reception time t _{receive (a)} (or the apparent propagation delay time Δt _(a) in the first time comparison information acquisition device 1a) as the fifth time comparison information acquisition device 1s. Send to.

On the other hand, the code transmitted from the first time comparison information acquisition device 1a with a time difference Δt _difference delayed from the timing at which the fifth time comparison information acquisition device 1s transmits the code at the comparison start time t _{0 (s)} is: A propagation delay time Δt _{delay (as)} determined according to the separation distance between the first time comparison information acquisition device 1a and the fifth time comparison information acquisition device 1s and the state of the propagation path has elapsed, and the first time comparison information acquisition device 1a. At the reception time t _{receive ( s) that} is delayed by the time difference Δt _difference from the reception time t _{receive (a)} , the fifth time comparison information acquisition device 1s is reached.

When the accuracy of the slave clock 6 is not high, the time difference Δt _{difference from} the first reference clock 1a becomes relatively large, and the code transmitted from the fifth time comparison information acquisition device 1s reaches the first time comparison information acquisition device 1a. the propagation delay time until Δt _{delay (sa),} contrary to the code transmitted from the first time comparison information acquisition apparatus 1a is the propagation delay time Delta] t _delay slightly to _(as) to reach the fifth time comparison information acquisition device 1s Although an error may occur, if it is treated _as “Δt _{delay (sa)} = Δt _{delay (as)} ”, the apparent propagation delay time Δt _(s) in the fifth time comparison information acquisition device 1 _s and the first From the apparent propagation delay time Δt _(a) in the time comparison information acquisition device 1a, the time difference Δt _difference between the first reference clock 3a and the slave clock 6 is obtained by Expression (3) ′.

Δt _difference = (Δt _(s) −Δt _(a) ) / 2 Equation (3) ′

Thus, the relative time difference Δt between the reference clock 3a corresponding to the first time comparison information acquisition device 1a as the master station and the slave clock 6 corresponding to the fifth time comparison information acquisition device 1s as the slave station. _{If the difference} can be acquired, the fifth time comparison information acquisition device 1s can correct the time of the slave clock 6 using the time difference Δt _difference as a correction amount.

The first time comparison information acquisition device 1a acquires time correction information Δt _correct that is a difference from the reference time calculated from the time differences of the plurality of reference clocks 3 belonging to the reference clock group from the time management server 4. In this case, the time correction information Δt _correct may also be transmitted to the fifth time comparison information acquisition device 1s. That is, if the time correction information Δt _correct of the first reference clock 3a is added to the relative time difference Δt _difference between the reference clock 3a and the slave clock 6 to obtain a correction amount, and the time of the slave clock 6 is corrected, the accuracy is further increased. It is possible to correct the time.

As described above, in the time comparison method of the timepiece according to the present invention, the accuracy of the propagation delay time Δt measured in both communication stations is directly linked to the accuracy of the time difference Δt _difference , so that the accuracy is higher. A communication system capable of obtaining the propagation delay time Δt will be described. In order to realize this function, the reception time acquisition means in the time comparison information acquisition apparatus 1 includes reception code storage means 121, correlation processing means 122, group delay / phase delay measurement means 123 (indicated by a broken line in FIG. 2). It was supposed to be prepared.

  The wireless communication processing means 16 of the time comparison information acquisition device 1 modulates the local code stored in the transmission code storage means 15 with a predetermined time signal (for example, a 10 MHz signal supplied from the reference clock 3). A signal is generated, and the modulated signal is converted into a phase and transmitted.

  The code transmitted from the other station is also converted into the same modulation signal, but the code is different from the own station code (code stored in the transmission code storage means 15). The code of the other station is notified from the server 4 via the wired network 5 before the time comparison operation starts. Since the code of the other station is stored and held in the reception code storage unit 121 of the reception time acquisition unit 12, the replica obtained by modulating the reception code of the other station with a predetermined time signal (for example, the same 10 MHz signal as that of the other station). A signal can be generated.

On the other hand, a reception signal from another station is supplied from the wireless communication processing means 16 to the reception time acquisition means 12, and correlation processing with the replica signal is performed by the correlation processing means 122. That is, the time from when comparison start time t _{0 at} which code transmission to another station is performed to when the group delay is obtained by the cross-correlation between the replica signal and the received modulation signal until a region where the cross-correlation function becomes a maximum value occurs. As the width, the propagation delay time Δt until the code signal from the other station is received can be obtained. However, since the accuracy below the wavelength of the correlation waveform cannot be obtained from the group delay, the amount of delay within one wavelength can be known by obtaining the phase delay. That is, the group delay / phase delay measuring unit 123 can measure the propagation delay time Δt with high accuracy from the group delay and the phase delay based on the correlation processing result by the correlation processing unit 122.

Since the group delay / phase delay measuring means 123 can directly determine the propagation delay time Δt, the propagation delay time Δt may be transmitted to the time management server 4 as it is, or calculated at the reception time t _receive . You may make it transmit again.

  As described above, the clock time comparison method and the clock time correction method according to the present invention have been described based on the embodiment applied to the communication system. However, the present invention is not limited to this embodiment alone, and All the time comparison methods and time correction methods of clocks that can be realized without changing the configuration described in the range are included as the scope of rights.

1a to 1d 1st to 4th time comparison information acquisition device 1s 5th time comparison information acquisition device 2 local cable 3a to 3d 1st to 4th reference clock 4 time management server 5 wired network 6 slave clock

Claims (6)

A comparison start time setting step in which a comparison start time t ₀ is set in advance in two wireless communication stations capable of starting communication in synchronization with the time of the comparison clock;
A code transmission step of mutually transmitting codes from each station to another station when the time of the comparison clock corresponding to each wireless communication station reaches the comparison start time t ₀ ;
A propagation delay time measuring step of measuring a propagation delay time Δt from when each communication station transmits a code to another station until receiving a code from the other station;
A time difference acquisition step of obtaining a time difference Δt _difference between two comparison watches based on two propagation delay times Δt measured at both communication stations;
A time comparison method for a clock, comprising: In the code transmission step,
A first process of generating a modulated signal by modulating a preset code of the own station with a predetermined time signal;
A second process of converting the modulated signal into a phase and transmitting the phase;
Including
In the propagation delay time measurement step,
A third step of performing correlation processing between the modulated signal received from the other station and the replica signal generated by modulating the code used by the other station with the time signal of the own station;
A fourth step of obtaining a group delay and a phase delay by the correlation processing to obtain a highly accurate propagation delay time Δt;
The time comparison method for a timepiece according to claim 1, comprising: Based on the clock time comparison method according to claim 1 or 2, the relative time difference Δt _difference between the master station corresponding to the clock with high reliability and the slave station corresponding to the clock with low reliability is _calculated . A time correction method for a timepiece obtained by acquiring the time difference Δt _difference as time correction information and correcting the time of the clock corresponding to the slave station. Based on the time comparison method of the timepiece according to claim 1 or 2, the relative time difference of all the timepieces in a reference timepiece group composed of three or more comparison timepieces that are subject to reference time calculation is calculated. Acquire each time difference Δt _difference between two stations in an identifiable combination,
Calculate the reference time in the reference clock group based on any reference time calculation method that uses the relative time difference of each clock,
The difference between the time of the time correction target clock and the reference time is obtained as time correction information Δt _correct ,
A time correction method for a timepiece, wherein the time of a time correction target timepiece is corrected based on the time correction information _Δtcorrect . A communication station corresponding to a reference clock belonging to the reference clock group is a master station,
A communication station corresponding to a clock that does not belong to the reference clock group is a slave station,
5. The relative time difference Δt _difference between the master station and the slave station is acquired, and the time of the clock corresponding to the slave station is corrected using the time difference Δt _difference as a correction amount. Time correction method for your watch. 6. The clock time corresponding to the slave station is corrected by adding the time correction information Δt _correct of the master station to the relative time difference Δt _difference between the master station and the slave station as a correction amount. The time correction method for the watch described in 1.

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