Time synchronization device

Abstract

To execute statistical time synchronization processing with high accuracy.SOLUTION: An information processing part 12 sequentially executes error measurement processing to acquire a timing error and a frequency error about a reference pulse signal and a local pulse signal with the lapse of time. The information processing part 12 calculates a timing control value and a frequency control value to the local pulse signal by statistical processing with a plurality of timing errors by error measurement processing executed over a plurality of times and a plurality of frequency errors by the error measurement processing executed over the plurality of times as a parent population. The information processing part 12 determines the size of the parent population in the statistical processing on the basis of the accuracy of the reference pulse signal or an operation state of the source of the local pulse signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a time synchronization device, and more particularly to a device that receives a reference pulse signal and performs time synchronization based on the reference pulse signal. [Background technology]

[0002] Wireless communication systems that include multiple base stations and multiple wireless communication terminals, with each wireless communication terminal communicating with one of the base stations, are widely used. Some wireless communication systems have multiple wireless communication terminals that communicate with one of the base stations in a time-division manner. Each wireless communication terminal changes the base station with which it communicates as it moves. To smoothly change the base station, time synchronization is performed between the base stations.

[0003] A base station that performs time synchronization receives a signal from a communication system such as a satellite positioning system, and extracts a reference signal synchronized with time (such as Coordinated Universal Time) from the received signal. For example, the base station described in Cited Document 1 extracts a 1PPS (1 Pulse Per Second) signal from a signal received from a GPS (Global Positioning System) satellite (GPS satellite) as a reference signal synchronized with time, and performs time synchronization processing using the 1PPS signal. Here, the 1PPS signal is a signal synchronized with Coordinated Universal Time and has a period of 1 second. The base station generates, for example, a clock signal synchronized with the 1PPS signal, and operates at a timing according to the clock signal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-88071 A [Patent Document 2] JP 2022-167388 A [Non-patent literature]

[0005] [Non-Patent Document 1] Toyoizumi, Genda, "Precise 1PPS signal output by GPS", Journal of Electrical Engineering C.125, Vol. 125, No. 8, 2005, p1217~p1222. Summary of the Invention [Problem to be solved by the invention]

[0006] Non-Patent Document 1 describes an error in the period of a 1PPS signal. It is generally known that a 1PPS signal has periodic fluctuations. It is also considered that a reference signal obtained from a satellite positioning system other than GPS may also have periodic fluctuations. In recent years, the operation speed of each device constituting a wireless communication system has increased, and if the period (frequency) of the reference signal fluctuates, the performance of the wireless communication system may not be fully demonstrated.

[0007] Therefore, Patent Document 2 proposes a technique for acquiring the timing error between a reference signal and a clock signal multiple times in the past, and controlling the frequency or phase of the clock signal according to the statistical value of the timing error acquired multiple times. However, in such a statistical synchronization process, the accuracy of the synchronization process may be insufficient depending on the way the population is selected when calculating the statistical value.

[0008] An object of the present invention is to perform statistical time synchronization processing with high accuracy. [Means for solving the problem]

[0009] The present invention comprises a receiving unit that extracts a reference pulse signal from a received signal obtained by receiving a radio signal, a local clock that generates a local pulse signal, and an information processing unit that controls the local clock, wherein the information processing unit sequentially executes error measurement processes over time to obtain a timing error based on a difference between the pulse timing indicated by the reference pulse signal and the pulse timing indicated by the local pulse signal, and a frequency error based on a difference between the timing error obtained for each of the earlier pulse timings and the timing error obtained for each of the later pulse timings, obtains a timing control value and a frequency control value by statistical processing with a population of a plurality of the timing errors obtained by the error measurement processes executed a plurality of times and a plurality of the frequency errors obtained by the error measurement processes executed a plurality of times, and executes an adjustment process that performs at least one of a process of adjusting the pulse timing of the local pulse signal by the timing control value and a process of adjusting the frequency of the local pulse signal by the frequency control value on the local pulse signal, and determines a population size in the statistical processing based on an accuracy of the reference pulse signal.

[0010] Preferably, the size of the population in the statistical processing is determined based on the accuracy of the reference pulse signal as well as the operating condition of the source of the local pulse signal.

[0011] The present invention includes a receiving unit that extracts a reference pulse signal from a received signal obtained by receiving a radio signal, a local clock that generates a local pulse signal, and an information processing unit that controls the local clock, wherein the information processing unit sequentially executes error measurement processes over time to obtain a timing error based on a difference between a pulse timing indicated by the reference pulse signal and the pulse timing indicated by the local pulse signal, and a frequency error based on a difference between the timing error obtained for each earlier pulse timing and the timing error obtained for each later pulse timing, obtains a timing control value and a frequency control value by statistical processing with a population of a plurality of the timing errors obtained by the error measurement processes executed a plurality of times and a plurality of the frequency errors obtained by the error measurement processes executed a plurality of times, and executes an adjustment process that performs at least one of a process of adjusting the pulse timing of the local pulse signal by the timing control value and a process of adjusting the frequency of the local pulse signal by the frequency control value on the local pulse signal, and determines a population size in the statistical processing based on an operating status of a source of the local pulse signal.

[0012] Preferably, the wireless signal is a signal transmitted from an artificial satellite, and the receiving unit Quality information indicating the accuracy of the reference pulse signal is generated based on the received signal, and the information processing unit performs the statistical processing based on the error measurement processing which has been performed a greater number of times the less accurate the quality information indicates.

[0013] Preferably, a temperature sensor is provided, and the information processing unit determines a temperature gradient based on the temperature indicated by the temperature sensor, and the smaller the temperature gradient, the more times the statistical processing is performed based on the error measurement processing which has been performed.

[0014] Desirably, the information processing unit performs a correction process based on the timing control value and the frequency control value in the latest adjustment process on a plurality of timing errors resulting from the error measurement process executed a plurality of times in the past and a plurality of frequency errors resulting from the error measurement process executed a plurality of times in the past, and then performs the statistical processing. Effect of the Invention

[0015] According to the present invention, statistical time synchronization processing can be executed with high accuracy. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 illustrates a configuration of a time synchronization device. [Diagram 2] 3A to 3C are diagrams illustrating examples of a time waveform of a 1PPS signal and a time waveform of a local pulse signal. [Diagram 3] FIG. 13 is a diagram conceptually illustrating a process for determining the latest timing control values ​​and frequency control values. [Figure 4] FIG. 13 is a diagram illustrating an example of the relationship between the passage of time and a timing error. [Diagram 5] 1A and 1B are diagrams illustrating an example of frequency fluctuation over time for a time signal and a local pulse signal generated by a local clock. [Figure 6] 11A and 11B are diagrams illustrating an example of frequency fluctuation when the temperature around the local clock changes. [Figure 7] FIG. 13 is a diagram conceptually illustrating an example of a population determination map. [Figure 8] 11A and 11B are diagrams showing specific examples of population determination maps. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 1 shows a configuration of a time synchronization device 100 according to an embodiment of the present invention. The time synchronization device 100 is mounted, for example, in a base station of a wireless communication system, and outputs a clock signal that defines the operation of the base station. The time synchronization device 100 includes a receiving unit 10, an information processing unit 12, a local clock 14, a time signal output unit 16, a memory 18, and a temperature sensor 20. The information processing unit 12 includes a timing comparison unit 22, a control unit 24, and a temperature gradient acquisition unit 26. All or a part of the components included in the information processing unit 12 (the timing comparison unit 22, the control unit 24, and the temperature gradient acquisition unit 26) may be configured by one or more processors that execute arithmetic processing by implementing a program.

[0018] The receiving unit 10 receives a radio signal transmitted from a GPS satellite, which is an artificial satellite. The receiving unit 10 extracts a 1PPS signal from the received signal obtained by receiving the radio signal, and outputs the 1PPS signal to the timing comparison unit 22. The 1PPS signal is a reference pulse signal that includes a pulse that rises every second.

[0019] The local clock 14 generates a time signal that specifies timing by pulses rising at equal time intervals, and outputs the time signal to the time signal output unit 16. The time signal output unit 16 outputs a clock signal synchronized with the timing indicated by the time signal. The time signal output unit 16 may generate a timing signal synchronized with the timing indicated by the time signal. The timing signal is a signal that specifies the operation timing of the device in which it is installed. The local clock 14 generates a local pulse signal that includes a pulse that rises every second, based on the time signal, and outputs the local pulse signal to the timing comparison unit 22.

[0020] The timing comparison unit 22 calculates a timing error t by subtracting the pulse timing of the local pulse signal from the pulse timing of the 1PPS signal. erris calculated sequentially over time. Here, the pulse timing in this embodiment refers to the time when the signal rises. When the pulse timing of the local pulse signal is delayed with respect to the pulse timing of the 1PPS signal, the timing error is negative, and when the pulse timing of the local pulse signal is advanced with respect to the pulse timing of the 1PPS signal, the timing error is positive.

[0021] 2A shows an example of a time waveform of a 1PPS signal, and FIG. 2B shows an example of a time waveform of a local pulse signal. In the example shown in FIG. 2, the local pulse signal is delayed from the 1PPS signal. The timing comparator 22 detects a timing error t err (j-1), where j is an integer equal to or greater than 1. The timing comparator 22 calculates a timing error t err Find (j).

[0022] For the j-th pulse timing of the local pulse signal and the 1PPS signal, the timing comparator 22 detects a frequency error f err (j) is calculated. Frequency error f err (j) is the timing error t when the j-th pulse of the local pulse signal and the 1PPS signal rises err From (j), the timing error t err (j-1) is subtracted. That is, f err (j)=t err (j)-t err (j-1). The frequency error f err (j) becomes positive when the frequency of the local pulse signal increases, and becomes negative when the frequency of the local pulse signal decreases.

[0023] The timing comparator 22 in FIG. err (j) and frequency error f errThe TF error TF(j) = [t err (j),f err (j)] are calculated and output to the control unit 24 in sequence over time.

[0024] In this way, the timing comparison unit 22 compares the timing error based on the difference between the pulse timing indicated by the 1PPS signal as the reference pulse signal and the pulse timing indicated by the local pulse signal with the timing error t err (j-1) and the timing error t obtained for each subsequent pulse timing err Frequency error f based on the difference with (j) err The error measurement process for obtaining (j) is executed sequentially over time.

[0025] The control unit 24 stores the TF errors TF(j) output from the timing comparison unit 22 in the memory 18 in sequence over time. Each TF error TF(j) stored in the memory 18 is corrected by the control unit 24 when performing statistical processing, which will be described later. This correction is performed by an overwriting process in which a value before correction is replaced with a value after correction.

[0026] The control unit 24 calculates a timing control value t by performing statistical processing on the latest TF error TF(i) and n TF errors TF(in) to TF(i-1) obtained before the latest TF error TF(i). c (i) and frequency control value f c (i) is calculated. Here, the timing control value t c (i) is a value indicating how much the pulse timing of the local pulse signal should be adjusted, and is the frequency control value f c (i) is a value indicating how much the frequency of the local pulse signal, that is, the interval of the pulse timing, should be adjusted. The statistical processing will now be described.

[0027] The control unit 24 detects the latest frequency error f err The frequency control value f corresponding to (i) c (i) is calculated according to the following equation (1), and the latest timing error terr (i) Timing control value t c (i) is calculated according to (Equation 2).

[0028]

number

[0029]

number

[0030] Here, the corrected timing error t err_c (k) (k=in to i) is calculated according to Equation 3.

[0031]

number

[0032] The frequency correction value fad(h) and the timing correction value tad(h) in (Equation 3) are determined according to (Equation 4) and (Equation 5), respectively.

[0033]

number

[0034]

number

[0035] The control unit 24 controls the local clock 14 so that the frequency of the local pulse signal output by the local clock 14 is adjusted to a frequency control value f c (i), and the rising edge of each pulse included in the local pulse signal is lowered by the timing control value t c The pulse timing of the time signal with which the local pulse signal is synchronized is adjusted so that it is delayed by (i).

[0036] Here, the frequency control value f obtained by (Equation 1) c (i) indicates the variation width of the timing error, that is, the average value of the frequency error, when it is assumed that the timing error changes in equal increments in the n-step time change from in to i. The timing control value t c (i) indicates the average value of the timing error from when the time variable changes from i-n+1 to i.

[0037] Moreover, (Equation 3) to (Equation 5) are the corrected timing error t err_c (k) is the original timing error t err FIG. 10(k) shows that the frequency control value and timing control value obtained at each past time step are cumulatively subtracted.

[0038] Figure 3 shows the latest timing control value t c (i) and frequency control value f c The process of calculating (i) according to (Equation 1) to (Equation 5) is conceptually shown. One rectangle shown in FIG. 3 is one TF error TF(j)=[t err (j),f err (j)]. The rightmost rectangle on the time axis represents the most recent TF error TF(i) = [t err (i),f err (i)].

[0039] In the first step S0, the control unit 24 performs statistical processing on the TF errors TF(-n) to TF(0) to obtain the latest timing control value t c (0) and frequency control value f c The control unit 24 calculates the timing error t(0) constituting the latest TF error TF(0). err (0) and frequency error f err (0) to the timing control value t c (0) and frequency control value f c (0) is subtracted to obtain the corrected TF error TF(0) (correction process SS0).

[0040] The control unit 24 executes the correction process SS0 and also executes an adjustment process for the local clock 14. That is, the control unit 24 controls the local clock 14 so that the frequency of the local pulse signal output by the local clock 14 is adjusted to a frequency control value f c (0), and the pulse timing of the local pulse signal is decreased by the timing control value t c The pulse timing of the time signal with which the local pulse signal is synchronized is adjusted so that it is delayed by (0).

[0041] In step S1, the control unit 24 calculates the timing errors t err (-n+1)~t err (0), the timing control value t c The control unit 24 further subtracts the frequency error f(−n+1) to the frequency error f(0) contained in each of the TF errors TF(−n+1) to TF(0). err (-n+1)~f err (0), the frequency control value f c (0) is subtracted from the TF error TF(−n+1) to TF(0) after correction (correction process ST0).

[0042] In step S1, the control unit 24 performs statistical processing on the TF errors TF(-n+1) to TF(1) to obtain the latest timing control value t c (1) and frequency control value f c The control unit 24 calculates the timing error t err (1) and frequency error f err From (1), the timing control value t c (1) and frequency control value f c (1) is subtracted to obtain the corrected TF error TF(1) (correction process SS1).

[0043] The control unit 24 executes the correction process SS1 and also executes an adjustment process for the local clock 14. That is, the control unit 24 controls the local clock 14 so that the frequency of the local pulse signal output by the local clock 14 is adjusted to a frequency control value f c (1), and the pulse timing of the local pulse signal is decreased by the timing control value t c The pulse timing of the time signal with which the local pulse signal is synchronized is adjusted so that it is delayed by (1).

[0044] In step S2, the control unit 24 calculates the timing errors t err (-n+2)~t err From each of (1), the timing control value t c The control unit 24 further subtracts the frequency error f(−n+2) to the frequency error f(1) contained in each of the TF errors TF(−n+2) to TF(1). err (-n+2)~f err From each of (1), the frequency control value f c (1) is subtracted. In this way, the corrected TF errors TF(-n+2) to TF(1) are obtained (correction process ST1).

[0045] In step S2, the control unit 24 performs statistical processing on the TF errors TF(-n+2) to TF(2) to obtain the latest timing control value t c (2) and frequency control value f c The control unit 24 calculates the timing error t err (2) and frequency error f err From (2), the timing control value t c (2) and frequency control value f c (2) is subtracted to obtain the corrected TF error TF(2) (correction process SS2).

[0046] The control unit 24 executes the correction process SS2 and also executes an adjustment process for the local clock 14. That is, the control unit 24 controls the local clock 14 so that the frequency of the local pulse signal output by the local clock 14 is adjusted to a frequency control value fc (2) and the pulse timing of the local pulse signal is decreased by the timing control value t c (2) Adjust the pulse timing of the time signal with which the local pulse signal is synchronized so that it is delayed by the time signal.

[0047] In this way, in step Sj, the control unit 24 calculates the timing errors t err (-n+j)~t err (j-1), the timing control value t c The control unit 24 further subtracts the frequency error f(j-1) contained in each of the TF errors TF(-n+j) to TF(j-1). err (-n+j)~f err (j-1), the frequency control value f c In this way, the corrected TF errors TF(-n+j) to TF(j-1) are obtained (correction process SSj).

[0048] In step Sj, the control unit 24 performs statistical processing on the TF errors TF(-n+j) to TF(j) to obtain the latest timing control value t c (j) and frequency control value f c The control unit 24 calculates the timing error t(j) constituting the latest TF error TF(j). err (j) and frequency error f err From (j), the timing control value t c (j) and frequency control value f c (j) is subtracted to obtain the corrected TF error TF(j) (correction process SSj).

[0049] The control unit 24 executes the correction process SSj and also executes an adjustment process for the local clock 14. That is, the control unit 24 controls the local clock 14 so that the frequency of the local pulse signal output by the local clock 14 is adjusted to a frequency control value f c (j), and the pulse of the local pulse signal is timing controlled by the timing control value t cThe pulse timing of the time signal with which the local pulse signal is synchronized is adjusted so that it is delayed by (j).

[0050] In step Sj where a TF error TF(j) is generated, each of the TF errors (-n+j) to (j-1) before the TF error TF(j) is calculated based on the timing control value t c (j-1) and frequency control value f c (j-1) (correction process STj-1).

[0051] Then, the latest timing control value t corresponding to the TF error TF(j) is calculated by statistical processing based on the TF error (-n+j) to the TF error (j). c (j) and frequency control value f c (j) is obtained (correction process SSj). Furthermore, the TF error TF(j) is calculated by multiplying the timing control value t c (j) and frequency control value f c As amended by subsection (j).

[0052] In this way, the control unit 24 performs a correction process based on the timing control value and frequency control value (timing error and frequency error) in the latest adjustment process on a plurality of timing errors resulting from error measurement processes executed a plurality of times in the past and a plurality of frequency errors resulting from error measurement processes executed a plurality of times in the past, and then performs statistical processing.

[0053] If the statistical processing is performed without performing the correction processing STj-1, the statistical processing is performed on a population of TF errors corrected by different timing control values ​​and different frequency control values. Therefore, the latest timing control value and frequency control value are not appropriate. According to the processing conceptually shown in FIG. 3, the statistical processing is performed on a population of TF errors corrected under the same conditions, and the latest timing control value and frequency control value are appropriately obtained.

[0054] As mentioned above, the timing control value t c (i) and frequency control value f c (i) is obtained by statistical processing using a population of multiple timing errors obtained by error measurement processing executed multiple times (n+1 times going back to the past including the latest processing) and multiple frequency errors obtained by error measurement processing executed multiple times (n+1 times going back to the past including the latest processing). More specifically, the timing control value t c (i) and frequency control value f c (i) is obtained by statistical processing of a population of n+1 TF errors including the latest TF error TF(i) and n TF errors obtained and corrected before the TF error TF(i).

[0055] In the time synchronization device 100 according to the present embodiment, the size of the population in the statistical processing is determined based on at least one of the accuracy of the 1PPS signal and the operating condition of the local clock 14 which is the source of the local pulse signal. Specifically, the number n+1 of TF errors used in the statistical processing may be determined based on one or both of quality information indicating the accuracy of the 1PPS signal and the ambient temperature of the local clock 14. The quality information is generated by the receiver 10 based on, for example, a positioning signal (wireless signal) transmitted from one or more GPS satellites. In the following description, the number n+1 of TF errors used in the statistical processing may be referred to as the population size N (N=n+1) of the statistical processing.

[0056] As shown in (Equation 1), the frequency error (frequency control value) is found by subtracting the timing error going back n times from the current time from the latest timing error and dividing the result by n equal parts. As shown in (Equation 2), the timing error (timing control value) is found by dividing the integral value, assuming that the timing error goes back n times from the current time and increases linearly with a constant gradient over n times, by n and averaging it. This constant gradient is the frequency error found according to (Equation 1). However, the actual timing error may not increase linearly from the timing error going back n times from the current time.

[0057] FIG. 4 shows an example of the relationship between the passage of time and the timing error. The horizontal axis indicates discrete time, and the vertical axis indicates the timing error. A characteristic 40 shows a timing error that increases linearly with the same gradient over n times from the timing error going back n times from the present time. A characteristic 42 shows a timing error whose gradient changes over time. If the frequency error is calculated by performing time integration on characteristic 40 according to (Equation 1) and (Equation 2) to calculate the average value, an error will occur between the frequency error calculated from the gradient of characteristic 42. This error will become larger the longer the time for calculating the frequency error is, i.e., the larger the population size N is.

[0058] In general, the larger the population size N of the statistical processing, the more appropriate it is to consider the timing error to change curvilinearly over time, and the less appropriate the linear approximation shown in (Equation 2) is. Also, the greater the change in temperature around the local clock 14, the greater the change in the time derivative of the timing error, and the less appropriate it is to consider the timing error to change curvilinearly over time. Therefore, the greater the change in temperature around the local clock 14, the less appropriate the linear approximation shown in (Equation 2) is.

[0059] Figure 5 shows an example of frequency fluctuation over time for the time signal and local pulse signal generated by the local clock 14. The horizontal axis shows time [sec], and the vertical axis shows frequency fluctuation [ppb]. However, the temperature around the local clock 14 is constant. In the example shown in Figure 5, a frequency fluctuation of 0.02083 ppb is observed over 3600 seconds.

[0060] Fig. 6 shows frequency fluctuations when the temperature around the local clock 14 changes. The horizontal axis shows the temperature gradient [°C / time], and the vertical axis shows the difference between the frequency error detection value and the true frequency error. In the example shown in Fig. 6, the greater the temperature gradient, the greater the frequency error detection value becomes relative to the true frequency.

[0061] In order to suppress the influence of such frequency error fluctuations, the control unit 24 reduces N as the temperature change (temperature gradient) per unit time around the local clock 14 increases. Such a time synchronization device 100 will be described with reference back to FIG. 1. The temperature sensor 20 sequentially measures the temperature around the local clock 14 over time, and outputs the measurement values ​​to the temperature gradient acquisition unit 26 sequentially over time. The temperature sensor 20 may be installed around the local clock 14. The temperature gradient acquisition unit 26 determines the temperature gradient [°C / time] based on the measurement values ​​sequentially output from the temperature sensor 20 over time, and outputs it to the control unit 24. The control unit 24 reduces the population size N as the temperature gradient increases, and increases the population size N as the temperature gradient decreases.

[0062] As mentioned above, it is known that the 1PPS signal has periodic fluctuations. If the TF errors corresponding to the N pulses indicated by the 1PPS signal are taken as a population, the distribution of the timing error on the horizontal axis and the occurrence frequency on the vertical axis will be a normal distribution, and the timing error with the highest occurrence frequency will be the average value. The larger the population size N, the higher the possibility that the timing error with the highest occurrence frequency, i.e., the average value of the timing errors, will be the true timing error.

[0063] Therefore, the receiver 10 generates quality information indicating the positioning accuracy based on the positioning signal transmitted from the GPS satellite. The quality information may be, for example, information indicating the level of the received positioning signal. The quality information may also be DOP (Dilution of Precision). DOP is a numerical value indicating the arrangement status of multiple GPS satellites. The smaller the DOP, the better the arrangement status and the higher the positioning accuracy. In addition, when the receiver 10 is placed in an environment where the reception status of the positioning signal transmitted from each GPS satellite is not good, the DOP becomes relatively large, and the positioning accuracy and the accuracy of the 1PPS signal become low.

[0064] The time synchronization device 100 may execute the following process. The receiving unit 10 generates quality information from a received signal based on a positioning signal transmitted from a GPS satellite, and outputs the quality information to the control unit 24. The control unit 24 increases the population size N as the positioning accuracy indicated by the quality information decreases, and decreases the population size N as the positioning accuracy indicated by the quality information increases. The receiving unit 10 generates, for example, a DOP as quality information from each received signal based on positioning signals transmitted from a plurality of GPS satellites. The smaller the DOP, the higher the positioning accuracy and the smaller the timing error of the 1PPS signal. And the larger the DOP, the lower the positioning accuracy and the larger the timing error of the 1PPS signal.

[0065] 7 conceptually illustrates an example of a population determination map for determining the population size N. The horizontal axis indicates the DOP, and the vertical axis indicates the temperature gradient obtained based on the measurement value by the temperature sensor 20. The population determination map is a map in which the population size N is associated with a set of DOP and temperature gradient. The population determination map may be stored in the control unit 24 or the memory 18. When the population determination map is stored in the memory 18, the control unit 24 refers to the population determination map stored in the memory 18. The control unit 24 obtains the population size N associated with the DOP and the temperature gradient, and performs statistical processing according to the population size N.

[0066] An example of a population decision map is shown in Figure 8. In the population decision map, if the DOP is less than 3, the DOP is identified as small. If the DOP is between 2 and less than 6, the DOP is identified as medium. If the DOP is 6 or more, the DOP is identified as large.

[0067] In addition, in the population determination map, if the temperature gradient is less than 2°C / hour, the temperature gradient is identified as small. If the temperature gradient is between 2°C / hour and 8°C / hour, the temperature gradient is identified as medium. If the temperature gradient is 8°C / hour or more, the temperature gradient is identified as large. For each of the three cases of small, medium, and large DOP, there are three cases of small, medium, and large temperature gradients, for a total of nine types of population sizes N.

[0068] The control unit 24 refers to the population determination map, acquires the population size N corresponding to the temperature gradient output from the temperature gradient acquisition unit 26 and the DOP output from the receiving unit 10, and performs statistical processing according to the population size N.

[0069] According to the population determination map, the less accurate the DOP as quality information is, the more times statistical processing based on error measurement processing is performed. Also, according to the population determination map, the smaller the temperature gradient is, the more times statistical processing based on error measurement processing is performed.

[0070] According to the time synchronization device 100 of this embodiment, an appropriate population size N for the statistical processing is determined based on the accuracy of the pulse timing of the 1PPS signal transmitted from a GPS satellite and the temperature characteristics of the local clock 14. This allows for highly accurate time synchronization processing to be performed in which the time signal and local pulse signal generated by the local clock 14 are synchronized with the 1PPS signal.

[0071] In the above, an embodiment has been shown in which the adjustment process is performed on both the timing error and the frequency error of the local pulse signal. The adjustment process may be performed on at least one of the timing error and the frequency error. In this case, the correction process performed on the multiple timing errors resulting from the error measurement process performed multiple times in the past and the multiple frequency errors resulting from the error measurement process performed multiple times in the past is performed in response to one or both of the timing errors and the frequency errors on which the adjustment process has been performed.

[0072] In the above embodiment, the GPS is used as the satellite positioning system, but other systems such as the Global Navigation Satellite System (GLONASS) may be used as the satellite positioning system.

[0073] [Configuration of the present invention] Configuration 1: A receiving unit that extracts a reference pulse signal from a received signal obtained by receiving a wireless signal; a local clock for generating a local pulse signal; an information processing unit that controls the local clock; The information processing unit includes: a timing error based on a difference between a pulse timing indicated by the reference pulse signal and a pulse timing indicated by the local pulse signal; Sequentially executing an error measurement process over time to obtain a frequency error based on a difference between the timing error obtained for each of the previous pulse timings and the timing error obtained for each of the subsequent pulse timings; determining a timing control value and a frequency control value by performing statistical processing on a population of a plurality of the timing errors obtained by the error measurement processing executed a plurality of times and a plurality of the frequency errors obtained by the error measurement processing executed a plurality of times; an adjustment process is performed on the local pulse signal, the adjustment process being at least one of a process of adjusting a pulse timing of the local pulse signal by the timing control value and a process of adjusting a frequency of the local pulse signal by the frequency control value; A time synchronization device, comprising: a time synchronization unit that determines a population size in the statistical processing based on the accuracy of the reference pulse signal. Configuration 2: A time synchronization device according to configuration 1, A time synchronization device characterized in that the size of the population in the statistical processing is determined based on the accuracy of the reference pulse signal as well as the operating status of a source of the local pulse signal. Configuration 3: a receiving unit that receives a wireless signal and extracts a reference pulse signal from the received signal; a local clock for generating a local pulse signal; an information processing unit that controls the local clock; The information processing unit includes: a timing error based on a difference between a pulse timing indicated by the reference pulse signal and a pulse timing indicated by the local pulse signal; Sequentially executing an error measurement process over time to obtain a frequency error based on a difference between the timing error obtained for each of the previous pulse timings and the timing error obtained for each of the subsequent pulse timings; determining a timing control value and a frequency control value by performing statistical processing on a population of a plurality of the timing errors obtained by the error measurement processing executed a plurality of times and a plurality of the frequency errors obtained by the error measurement processing executed a plurality of times; an adjustment process is performed on the local pulse signal, the adjustment process being at least one of a process of adjusting a pulse timing of the local pulse signal by the timing control value and a process of adjusting a frequency of the local pulse signal by the frequency control value; A time synchronization device, comprising: a signal processing unit that determines a population size in the statistical processing based on an operating status of a source that generates the local pulse signal; Configuration 4: A time synchronization device according to the first or second aspect of the present invention, the radio signal is a signal transmitted from an artificial satellite, The receiving unit is generating quality information indicating accuracy of the reference pulse signal based on the received signal; The information processing unit includes: A time synchronization device, characterized in that the less accurate the quality information indicates, the more times the statistical processing is performed based on the error measurement processing that has been performed. Configuration 5: A time synchronization device according to configuration 2 or 3, Equipped with a temperature sensor, The information processing unit includes: A temperature gradient is calculated based on the temperature indicated by the temperature sensor; A time synchronization device characterized in that the smaller the temperature gradient, the more times the statistical processing is performed based on the error measurement processing that has been performed. Configuration 6: A time synchronization device according to any one of configurations 1 to 5, The information processing unit includes: A time synchronization device characterized by performing a correction process based on the timing control value and frequency control value in the latest adjustment process on a plurality of timing errors resulting from the error measurement process that has been performed a plurality of times in the past and a plurality of frequency errors resulting from the error measurement process that has been performed a plurality of times in the past, and then performing the statistical processing. [Explanation of symbols]

[0074] 10 receiving unit, 12 information processing unit, 14 local clock, 16 time signal output unit, 18 memory, 20 temperature sensor, 22 timing comparison unit, 24 control unit, 26 temperature gradient acquisition unit, 40, 42 characteristics, 100 time synchronization device.

Claims

1. a receiving unit that receives a wireless signal and extracts a reference pulse signal from the received signal; a local clock for generating a local pulse signal; an information processing unit that controls the local clock; The information processing unit includes: a timing error based on a difference between a pulse timing indicated by the reference pulse signal and a pulse timing indicated by the local pulse signal; Sequentially executing an error measurement process over time to obtain a frequency error based on a difference between the timing error obtained for each of the previous pulse timings and the timing error obtained for each of the subsequent pulse timings; determining a timing control value and a frequency control value by performing statistical processing on a population of a plurality of the timing errors obtained by the error measurement processing executed a plurality of times and a plurality of the frequency errors obtained by the error measurement processing executed a plurality of times; an adjustment process is performed on the local pulse signal, the adjustment process being at least one of a process of adjusting a pulse timing of the local pulse signal by the timing control value and a process of adjusting a frequency of the local pulse signal by the frequency control value; A time synchronization device, comprising: a time synchronization unit that determines a population size in the statistical processing based on the accuracy of the reference pulse signal.

2. 2. The time synchronization device according to claim 1, A time synchronization device characterized in that the size of the population in the statistical processing is determined based on the accuracy of the reference pulse signal as well as the operating status of a source of the local pulse signal.

3. a receiving unit that receives a wireless signal and extracts a reference pulse signal from the received signal; a local clock for generating a local pulse signal; an information processing unit that controls the local clock; The information processing unit includes: a timing error based on a difference between a pulse timing indicated by the reference pulse signal and a pulse timing indicated by the local pulse signal; Sequentially executing an error measurement process over time to obtain a frequency error based on a difference between the timing error obtained for each of the previous pulse timings and the timing error obtained for each of the subsequent pulse timings; determining a timing control value and a frequency control value by performing statistical processing on a population of a plurality of the timing errors obtained by the error measurement processing executed a plurality of times and a plurality of the frequency errors obtained by the error measurement processing executed a plurality of times; an adjustment process is performed on the local pulse signal, the adjustment process being at least one of a process of adjusting a pulse timing of the local pulse signal by the timing control value and a process of adjusting a frequency of the local pulse signal by the frequency control value; A time synchronization device, comprising: a signal processing unit that determines a population size in the statistical processing based on an operating status of a source that generates the local pulse signal;

4. 3. The time synchronization device according to claim 1, the radio signal is a signal transmitted from an artificial satellite, The receiving unit is generating quality information indicating accuracy of the reference pulse signal based on the received signal; The information processing unit includes: A time synchronization device, characterized in that the less accurate the quality information indicates, the more times the statistical processing is performed based on the error measurement processing that has been performed.

5. The time synchronization device according to claim 2 or 3, Equipped with a temperature sensor, The information processing unit includes: A temperature gradient is calculated based on the temperature indicated by the temperature sensor; A time synchronization device characterized in that the smaller the temperature gradient, the more times the statistical processing is performed based on the error measurement processing that has been performed.

6. The time synchronization device according to any one of claims 1 to 3, The information processing unit includes: A time synchronization device characterized by performing a correction process based on the timing control value and frequency control value in the latest adjustment process on a plurality of timing errors resulting from the error measurement process that has been performed a plurality of times in the past and a plurality of frequency errors resulting from the error measurement process that has been performed a plurality of times in the past, and then performing the statistical processing.

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