Time synchronization system

Abstract

The invention discloses a time synchronization system. In a configuration in which an oscillator is included in a time synchronization system, there is a case in which, for example, the frequency stability of the entire time synchronization system decreases even if statistical processing is performed, along with deterioration of the oscillator over time. A time synchronization system (1) is provided with: a plurality of synchronization sources (100) each outputting time information; and a calculation unit (200) that executes a predetermined process on each time information output from the plurality of synchronization sources (100), each of the plurality of synchronization sources (100) is provided with an oscillator (30) and a detection unit (40) that outputs fluctuation information of the oscillator (30), and the calculation unit (200) changes the predetermined process executed on the time information on the basis of the fluctuation information output from the detection unit (40) of each of the plurality of synchronization sources (100).

Description

Technical Field

[0001] The invention relates to a time synchronization system. Background Art

[0002] Conventionally, a time synchronization system is known that includes: a plurality of synchronization sources, each of which includes an oscillator and outputs time information; and a computing unit that performs predetermined processing on each of the time information output from the plurality of synchronization sources connected to a network. For example, Patent Document 1 discloses a time synchronization network that is connected to a plurality of communication devices having synchronization sources such as a crystal oscillator and an atomic clock, and corrects the time information by performing offset processing on the time difference information between the communication devices.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2022-14406

[0004] However, the oscillator of the synchronization source has a life span and will degrade over time. In the time synchronization network disclosed in Patent Document 1, the time information is corrected by performing bias processing, but if the oscillator degrades over time, the frequency stability is reduced and the correction accuracy is reduced. In this way, in the previous time synchronization system, even if statistical processing is performed as the oscillator degrades over time, the frequency stability of the time synchronization system as a whole may be reduced. Summary of the invention

[0005] The time synchronization system of the present invention for solving the above-mentioned technical problem is characterized in that the time synchronization system comprises a plurality of synchronization sources and a computing unit, the plurality of synchronization sources respectively output time information, the computing unit performs predetermined processing on each of the time information output from the plurality of synchronization sources, the plurality of synchronization sources respectively comprise an oscillator and a detection unit that outputs change information of the oscillator, and the computing unit changes the predetermined processing performed on the time information based on the change information output from the detection unit of each of the plurality of synchronization sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a diagram showing a time synchronization system according to the first embodiment of the present invention.

[0007] Figure 2 Yes means Figure 1 Diagram of a circuit block for capturing resonance signal strength in an oscillator of a synchronization source of a timing synchronization system.

[0008] Figure 3 It is a diagram showing a time synchronization system according to a second embodiment of the present invention.

[0009] Description of Reference Numerals

[0010] 1: time synchronization system; 1A: time synchronization system; 1B: time synchronization system; 30: oscillator (atomic oscillator); 31: light source; 32: gas unit; 33: photodiode; 34: detection circuit; 35: crystal oscillator; 36: phase circuit; 37: PLL; 38: oscillator; 40: detection unit; 41: diode; 42: analog-to-digital converter; 50: storage unit; 60: environmental sensing block; 100: synchronization source; 200: operation unit. DETAILED DESCRIPTION

[0011] First, the present invention will be roughly described.

[0012] A first aspect of the present invention for solving the above-mentioned technical problem is characterized in that the time synchronization system comprises a plurality of synchronization sources and a computing unit, the plurality of synchronization sources respectively outputting time information, the computing unit performing predetermined processing on each of the time information outputted from the plurality of synchronization sources, the plurality of synchronization sources respectively comprising an oscillator and a detection unit outputting change information of the oscillator, the computing unit changing the predetermined processing performed on the time information based on the change information outputted from the detection unit of each of the plurality of synchronization sources.

[0013] According to this aspect, a plurality of synchronization sources and a computing unit are provided, each synchronization source is provided with an oscillator and a detection unit that outputs the variation information of the oscillator, and the computing unit changes the predetermined processing performed on the time information based on the variation information output from the detection unit of each synchronization source. That is, the degradation of the oscillator over time can be detected by the detection unit that outputs the variation information of the oscillator. Therefore, when the degradation of the oscillator over time is detected, the predetermined processing can be changed based on the information, so that the reduction of the frequency stability when the time synchronization system is viewed as a whole can be suppressed.

[0014] A second aspect of the time synchronization system of the present invention is an aspect subordinate to the first aspect, and is characterized in that the change information includes at least one of information related to intensity changes of the resonance signal of the oscillator and information related to environmental changes around the synchronization source.

[0015] According to this aspect, the variation information includes at least one of information related to the variation in the intensity of the resonance signal of the oscillator and information related to the variation in the environment around the synchronization source. The variation in the intensity of the resonance signal of the oscillator and the variation in the environment around the synchronization source are related to the reduction in frequency stability. By changing the predetermined processing performed on the time information based on this information, the reduction in frequency stability when viewed from the perspective of the time synchronization system as a whole can be suppressed.

[0016] A time synchronization system according to a third aspect of the present invention is an aspect dependent on the first or second aspect, and is characterized in that the predetermined processing is statistical processing of the time information outputted from each of the plurality of synchronization sources.

[0017] According to this aspect, the predetermined processing is statistical processing on the time information outputted from the plurality of synchronization sources, respectively. Therefore, it is possible to perform statistical processing on the time information outputted from the respective synchronization sources with high accuracy.

[0018] A time synchronization system according to a fourth aspect of the present invention is dependent on the third aspect, and is characterized in that the calculation unit changes the weight of the time information output from the corresponding synchronization source in the statistical processing based on the change information.

[0019] According to this aspect, the calculation unit changes the weight of the time information output from the corresponding synchronization source in the statistical processing based on the change information. Therefore, by increasing the weight of the time information with high reliability and decreasing the weight of the time information with low reliability, the predetermined processing can be performed well.

[0020] A time synchronization system according to a fifth aspect of the present invention is an aspect subordinate to the first or second aspect, and is characterized in that the oscillator is an atomic oscillator.

[0021] According to this aspect, the oscillator is an atomic oscillator that can output a clock signal with high frequency accuracy using atomic energy transition. Therefore, in a time synchronization system having an atomic oscillator requiring high accuracy as an oscillator, it is possible to suppress a decrease in frequency stability when the time synchronization system as a whole is viewed.

[0022] Example 1

[0023] Next, a time synchronization system 1 according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 and Figure 2 A time synchronization system 1A according to a first embodiment of the present invention will be described. Figure 1 1A is a diagram showing a time synchronization system 1A of the present embodiment. Figure 1 As shown, the time synchronization system 1A of the present embodiment is the following time synchronization system 1, comprising: a plurality of synchronization sources 100, each of which has an oscillator 30 and outputs time information; a calculation unit 200, which performs ensemble statistical processing as a predetermined processing on each time information output from these plurality of synchronization sources 100 connected on a wired or wireless network; and a storage unit 50, which stores various information.

[0024] like Figure 1As shown, each of the plurality of synchronization sources 100 includes an oscillator 30 and a detection unit 40 that outputs variation information of the oscillator 30. Here, the operation unit 200 can change the predetermined processing performed on the time information based on the variation information output from each of the detection units 40 of the plurality of synchronization sources 100. In other words, the time synchronization system 1A of the present embodiment can detect the temporal degradation of the oscillator 30 by including the detection unit 40 that outputs the variation information of the oscillator 30. Therefore, when the temporal degradation of the oscillator 30 is detected, the predetermined processing can be changed based on the information, so that the reduction in frequency stability when the time synchronization system 1 is viewed as a whole can be suppressed.

[0025] Here, in the time synchronization system 1A of the present embodiment, as described above, the oscillator 30 is an atomic oscillator. Therefore, in the time synchronization system 1A of the present embodiment, in the time synchronization system 1 having an atomic oscillator requiring high accuracy as the oscillator 30, it is possible to suppress a decrease in frequency stability when the time synchronization system 1 is viewed as a whole.

[0026] Below, refer to Figure 2 The oscillator 30 and the detector 40 are described in more detail. The oscillator 30 of the present embodiment is an atomic oscillator that can output a clock signal with a high frequency accuracy using energy transition of atoms. Figure 2 1 is a block diagram showing the electrical configuration of the oscillator 30 and the detector 40 , and is a diagram showing a circuit block for capturing the resonance signal strength in the oscillator 30 of the synchronization source 100 of the time synchronization system 1A of the present embodiment.

[0027] like Figure 2 As shown, the oscillator 30 includes: a light source 31 as a light emitting portion for emitting light, a gas cell 32, and a photodiode 33 as a light receiving portion. It should be noted that the light source 31 and the gas cell 32 have a life span and may deteriorate over time. If the light source 31 and the gas cell 32 deteriorate over time, the frequency stability is likely to decrease.

[0028] The oscillator 30 has a detection circuit 34 as a scan result output unit that outputs a scan result signal corresponding to a resonance signal obtained by frequency scanning in the oscillator 30. The oscillator 30 also has a crystal oscillator (voltage controlled crystal oscillator: VCXO) 35 as a voltage controlled oscillator (VCO), a phase circuit 36, a PLL (Phase Locked Loop) 37, and an oscillator 38.

[0029] As the light source 31, for example, a semiconductor laser can be used. For example, gaseous alkali metals such as rubidium, cesium, and sodium are sealed in the gas cell 32. The photodiode 33 receives light emitted from the light source 31 and transmitted through the gas cell 32, performs photoelectric conversion, and outputs it as an electrical signal.

[0030] The crystal oscillator 35 is not particularly limited, and for example, an oven controlled quartz crystal oscillator (OCXO), a temperature compensated quartz crystal oscillator (TCXO), etc. can be used. The detection circuit 34 has a function of outputting a scan result signal corresponding to (equivalent to) the resonance signal (EIT signal) obtained by frequency scanning in the oscillator 30 .

[0031] Next, the scanning result signal generated by the oscillator 30 will be further described. Next, for ease of understanding, as an example, the frequency of each signal is described using specific numerical values. First, gaseous rubidium with a frequency ω0 of 9.2 GHz for generating atomic resonance is sealed in the gas cell 32, and the oscillator 38 is made to output a signal of 111 Hz.

[0032] The signal with frequency f output from the crystal oscillator 35 is modulated to a frequency of 111 Hz by the phase circuit 36 ​​and is then modulated to a frequency of 4.1×10 7 The frequency is doubled to 4.6 GHz and outputted to the light source 31. In this way, when the frequency is scanned with a signal having a frequency of 111 Hz, an atomic resonance, namely an electromagnetically induced transparency (EIT) phenomenon, occurs at a predetermined timing in the gas cell 32, and a steep signal, namely an atomic resonance signal (EIT signal), which is generated along with the EIT phenomenon, is generated.

[0033] When the atomic resonance is not generated, a signal with a frequency of 111 Hz is input from the photodiode 33 to the detection circuit 34. However, when the atomic resonance is generated, a signal with a frequency of 222 Hz, i.e., a double wave relative to 111 Hz, is input from the photodiode 33 to the detection circuit 34 instead of a signal with a frequency of 111 Hz. The signal with a frequency of 222 Hz when the atomic resonance is generated is a scan result signal, and the scan result signal is output from the detection circuit 34 to the detection unit 40 as a double wave level detection unit.

[0034] The detection unit 40 includes a diode 41 and an analog-to-digital converter 42. The detection unit 40 receives an analog value from the oscillator 30, converts the analog value into a digital value, and outputs the digital value to the calculation unit 200.

[0035] The detection circuit 34 performs control so that the amplitude of the signal with a frequency of 111 Hz input from the photodiode 33 to the detection circuit 34 becomes 0. That is, the detection circuit 34 performs control so that the signal with a frequency of 111 Hz is not input from the photodiode 33 to the detection circuit 34 .

[0036] Here, an example of the double wave level detection process is described. The following double wave level detection process is executed in the operation unit 200. First, in each synchronization source 100, after 1 day (24 hours) from the time when the synchronization source 100 is powered on, the digital detection value output from the analog-to-digital converter 42 is stored in the storage unit 50. Next, the digital detection value output from the analog-to-digital converter 42 is obtained every day, and compared with the digital detection value stored in the storage unit 50, and the change amount is calculated. Then, the operation unit 200 performs statistical processing of the time of multiple synchronization sources 100 based on the size of the change amount.

[0037] As described above, the variation information of the oscillator 30 in the time synchronization system 1A of the present embodiment is information related to the intensity variation of the resonance signal of the oscillator 30. Thus, the variation information preferably includes information related to the intensity variation of the resonance signal of the oscillator 30. The intensity variation of the resonance signal of the oscillator 30 is related to the reduction of the frequency stability, but by changing the predetermined processing (the ensemble statistical processing based on the above-mentioned two-fold wave level detection processing) performed on the time information based on the information related to the intensity variation of the resonance signal of the oscillator 30, it is possible to suppress the reduction of the frequency stability when the time synchronization system 1 is viewed as a whole.

[0038] In addition, as described above, the predetermined processing (ensemble statistical processing based on the above-mentioned double wave level detection processing) in the time synchronization system 1A of the present embodiment is statistical processing on the time information output from each of the plurality of synchronization sources 100. Therefore, the time synchronization system 1A of the present embodiment can perform statistical processing on the time information output from each synchronization source 100 with high accuracy.

[0039] Here, the operation unit 200 changes the weight of the time information output from the corresponding synchronization source 100 in the statistical processing based on the change information of the oscillator 30 in the predetermined processing (the ensemble statistical processing based on the above-mentioned double wave level detection processing). Specifically, the weight of the time information with high reliability is increased and the weight of the time information with low reliability is reduced. By performing such processing, the predetermined processing can be well performed.

[0040] Next, an example of the weight of the time information in the statistical processing is described. The time synchronization system 1A of the present embodiment executes a statistical processing mode, which uses the change amount when compared with the digital detection value stored in the storage unit 50 as the resonance signal change amount, and changes the weight of the synchronization source 100 based on the resonance signal change amount. In the following Table 1, the correlation between the resonance signal change amount, the weight of the synchronization source 100, and the statistical processing mode is summarized. However, in the present invention, the weight of the synchronization source 100 based on the resonance signal change amount is not limited to the weight shown below.

[0041] [Table 1]

[0042]

[0043] As shown in Table 1, the time synchronization system 1A of the present embodiment is set to Mode 1 in which the weight of the synchronization source 100 is 0.8 when the resonance signal variation is 1% or more and less than 5%. It should be noted that, although omitted in Table 1, when the resonance signal variation is less than 1%, the mode 0 is set to 1 in which the weight of the synchronization source 100 is 1. Similarly, when the resonance signal variation is 5% or more and less than 10%, the time synchronization system 1A of the present embodiment is set to Mode 2 in which the weight of the synchronization source 100 is 0.6, and when the resonance signal variation is 10% or more and less than 20%, the mode 3 is set to 0.4. On the other hand, when the resonance signal variation is 20% or more, the time synchronization system 1A of the present embodiment determines that the resonance signal variation is too large, and sets the weight to 0, that is, the information of the synchronization source 100 is not used. Mode 4.

[0044] Example 2

[0045] Next, use Figure 3 The time synchronization system 1B of the second embodiment is described. It should be noted that: Figure 3 is the same as that in the time synchronization system 1A of the first embodiment. Figure 1 The corresponding figure. Figure 3 In the embodiment, the same components as those in the first embodiment are indicated by the same reference numerals, and detailed descriptions are omitted. Here, except for the parts described below, the time synchronization system 1B of this embodiment has the same configuration as the time synchronization system 1A of the first embodiment. Therefore, except for the parts described below, the time synchronization system 1B of this embodiment has the same features as the time synchronization system 1A of the first embodiment.

[0046] like Figure 3As shown, the synchronization source 100 of the time synchronization system 1B of the present embodiment is further provided with an environment sensor block 60 in addition to the synchronization source 100 of the time synchronization system 1A of the first embodiment. Therefore, in addition to the ensemble statistical processing based on the resonance signal variation amount that can be performed by the time synchronization system 1A of the first embodiment, the ensemble statistical processing can also be performed based on the detection information detected by the environment sensor block 60. The environment sensor block 60 of the time synchronization system 1B of the present embodiment is configured to detect the environment around the synchronization source 100, and specifically, is configured to detect the temperature of the area where the synchronization source 100 is located, the vibration of the area where the synchronization source 100 is located, the magnetic field of the area where the synchronization source 100 is located, the radiation of the area where the synchronization source 100 is located, and the like.

[0047] Therefore, the operation unit 200 of the time synchronization system 1B of the present embodiment can change the predetermined processing executed on the time information based on the change information output from the detection units 40 of each of the plurality of synchronization sources 100, and can change the predetermined processing executed on the time information based on the information related to the environmental change around the synchronization source 100 as the change information. Therefore, the time synchronization system 1B of the present embodiment can suppress the reduction of the frequency stability when the time synchronization system 1 is viewed as a whole by changing the predetermined processing (ensemble statistical processing) executed on the time information based on the information related to the environmental change around the synchronization source 100.

[0048] In addition, the time synchronization system 1B of the present embodiment can change the weight of the time information output from each of the plurality of synchronization sources 100 in the statistical processing based on the information related to the environmental change around the synchronization source 100. An example of the weight of the time information in the statistical processing is described below. The time synchronization system 1B of the present embodiment executes a statistical processing mode, which changes the weight of the synchronization source 100 based on the environmental change amount composed of the temperature change amount from the standard value (temperature one day ago), the vibration change amount from the standard value (0G), the magnetic field change amount from the standard value (0Gauss), and the radiation change amount from the standard value (0rad) as the detection result of the environmental sensor block 60.

[0049] In the following Tables 2 to 5, the correlation between the environmental variation, the weight of the synchronization source 100, and the statistical processing mode is summarized. Specifically, the correlation between the temperature variation, the weight of the synchronization source 100, and the statistical processing mode is summarized in the following Table 2, the correlation between the vibration variation, the weight of the synchronization source 100, and the statistical processing mode is summarized in the following Table 3, the correlation between the magnetic field variation, the weight of the synchronization source 100, and the statistical processing mode is summarized in the following Table 4, and the correlation between the radiation variation, the weight of the synchronization source 100, and the statistical processing mode is summarized in the following Table 5. However, the weight of the synchronization source 100 based on such environmental variation in the present invention is not limited to the weight described below.

[0050] [Table 2]

[0051]

[0052] As shown in Table 2, the time synchronization system 1B of the present embodiment sets the weight of the synchronization source 100 to 0.8 in Mode 1 when the temperature variation is 20°C or more and less than 40°C. It should be noted that, although omitted in Table 2, when the temperature variation is less than 20°C, the weight of the synchronization source 100 is set to 1 in Mode 0. Similarly, when the temperature variation is 40°C or more and less than 60°C, the time synchronization system 1B of the present embodiment sets the weight of the synchronization source 100 to 0.6 in Mode 2, and when the temperature variation is 60°C or more and less than 80°C, the weight of the synchronization source 100 is set to 0.4 in Mode 3. On the other hand, when the temperature variation is 80°C or more, the time synchronization system 1B of the present embodiment determines that the temperature variation is too large and sets the weight to 0, that is, the information of the synchronization source 100 is not used in Mode 4.

[0053] [Table 3]

[0054]

[0055] As shown in Table 3, the time synchronization system 1B of this embodiment has a vibration variation of 0.001G or more and less than 0.01G (1G = 9.8m / s 2), the mode 1 in which the weight of the synchronization source 100 is 0.8 is set. It should be noted that, although omitted in Table 3, when the vibration variation is less than 0.001G, the mode 0 in which the weight of the synchronization source 100 is 1 is set. Similarly, when the vibration variation is greater than 0.01G and less than 0.1G, the time synchronization system 1B of this embodiment is set to mode 2 in which the weight of the synchronization source 100 is 0.6, and when the vibration variation is greater than 0.1G and less than 1G, the mode 3 in which the weight of the synchronization source 100 is 0.4. On the other hand, when the vibration variation is greater than 1G, the time synchronization system 1B of this embodiment determines that the vibration variation is too large, and sets the weight to 0, that is, the mode 4 in which the information of the synchronization source 100 is not used.

[0056] [Table 4]

[0057]

[0058] As shown in Table 4, the time synchronization system 1B of this embodiment is set to Mode 1 in which the weight of the synchronization source 100 is 0.8 when the magnetic field variation is greater than or equal to 0.01 Gauss and less than 0.1 Gauss. It should be noted that, although omitted in Table 4, when the magnetic field variation is less than 0.01 Gauss, the mode 0 is set to which the weight of the synchronization source 100 is 1. Similarly, when the magnetic field variation is greater than or equal to 0.1 Gauss and less than 1 Gauss, the time synchronization system 1B of this embodiment is set to Mode 2 in which the weight of the synchronization source 100 is 0.6, and when the magnetic field variation is greater than or equal to 1 Gauss and less than 10 Gauss, the mode 3 is set to which the weight of the synchronization source 100 is 0.4. On the other hand, when the magnetic field variation is greater than or equal to 10 Gauss, the time synchronization system 1B of this embodiment determines that the magnetic field variation is too large and sets the weight to 0, that is, the information of the synchronization source 100 is not used. Mode 4.

[0059] [Table 5]

[0060]

[0061] As shown in Table 5, the time synchronization system 1B of the present embodiment sets the weight of the synchronization source 100 to 0.8 in Mode 1 when the radiation fluctuation amount is 10 rad or more and less than 100 rad (100 rad=1 Gy). It should be noted that, although omitted in Table 5, when the radiation fluctuation amount is less than 10 rad, the weight of the synchronization source 100 is set to Mode 0, which is 1. Similarly, when the radiation fluctuation amount is 100 rad or more and less than 1000 rad, the time synchronization system 1B of the present embodiment sets the weight of the synchronization source 100 to 0.6 in Mode 2, and when the radiation fluctuation amount is 1000 rad or more and less than 10000 rad, the weight of the synchronization source 100 is set to Mode 3, which is 0.4. On the other hand, when the radiation fluctuation amount is 10000 rad or more, the time synchronization system 1B of the present embodiment determines that the vibration fluctuation amount is too large, and sets the weight to 0, that is, the information of the synchronization source 100 is not used in Mode 4.

[0062] The present invention is not limited to the above-mentioned embodiments, and can be implemented by various configurations within the scope of the main purpose. In order to solve part or all of the above-mentioned technical problems, or to achieve part or all of the above-mentioned effects, the technical features in the embodiments corresponding to the technical features in the various aspects recorded in the summary of the invention can be appropriately replaced or combined. In addition, if the technical feature is not described as necessary in this specification, it can be appropriately deleted.

Claims

1. A time synchronization system, characterized in that: The time synchronization system includes a plurality of synchronization sources and a computing unit, wherein the plurality of synchronization sources respectively output time information, and the computing unit performs predetermined processing on each of the time information output from the plurality of synchronization sources. The plurality of synchronization sources each include an oscillator and a detection unit that outputs variation information of the oscillator. The calculation unit changes the predetermined processing executed on the time information based on the change information output from the detection unit of each of the plurality of synchronization sources.

2. The time synchronization system according to claim 1, characterized in that: The variation information includes at least one of information related to variation in intensity of a resonance signal of the oscillator and information related to variation in an environment around the synchronization source.

3. The time synchronization system according to claim 1 or 2, characterized in that: The predetermined processing is statistical processing on the time information outputted from each of the plurality of synchronization sources.

4. The time synchronization system according to claim 3, characterized in that: The calculation unit changes the weight of the time information output from the corresponding synchronization source in the statistical processing based on the change information.

5. The time synchronization system according to claim 1 or 2, characterized in that: The oscillator is an atomic oscillator.

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