CN115903443B - Time calibration system and method for satellite - Google Patents
Time calibration system and method for satellite Download PDFInfo
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Abstract
The application discloses a time calibration system and a method for satellites, wherein the system comprises the following steps: the system comprises an SMU processor module and a navigation satellite system module in communication with the SMU processor module, wherein the navigation satellite system module is configured to receive a pulse-per-second signal from the navigation satellite system and a time service data packet and transmit the pulse-per-second signal to the SMU processor module. The SMU processor module is configured to: generating satellite local crystal oscillator clock time based on an oscillation signal of the crystal oscillator; determining first time information corresponding to the second pulse signal according to the clock time of the crystal oscillator; acquiring a time service data packet corresponding to the second pulse signal, and determining second time information corresponding to the second pulse signal according to the acquired time service data packet; and determining a time deviation value of the time of the crystal oscillator clock according to the first time information and the second time information.
Description
Technical Field
The present application relates to the field of satellite time management, and in particular, to a time calibration system and method for satellites.
Background
Satellite systems are provided with a satellite time management system, which is mainly used for providing a time reference for whole-satellite operation, wherein time calibration is an important task of the satellite time management system. GNSS (global navigation satellite system) timing is the primary way of satellite timing.
The existing GNSS timing method is as follows: the satellite receives PPS (pulse per second) signals transmitted by the GNSS system, while the satellite generates PPS signals locally based on a real-time clock module of the crystal oscillator. The satellite determines the deviation value of the local crystal oscillator clock time of the satellite by comparing the phase difference between the two PPS signals, and corrects the real-time clock module based on the crystal oscillator. However, the process of calculating the time deviation value using the phase difference is complicated and the time cost is high.
Aiming at the technical problems that in the prior art, the process of calculating the time deviation value according to the phase difference between the PPS signal of the GNSS system and the PPS signal generated by the real-time clock module is complicated and the time cost is high, no effective solution is proposed at present.
Disclosure of Invention
The disclosure provides a time calibration system and a time calibration method for satellites, which at least solve the technical problems in the prior art that the process of calculating a time deviation value according to the phase difference between a PPS signal of a GNSS system and a PPS signal generated by a real-time clock module is complicated and the time cost is high.
According to one aspect of the present application there is provided a time alignment system for a satellite comprising: the system comprises an SMU processor module and a navigation satellite system module in communication with the SMU processor module, wherein the navigation satellite system module is configured to receive a pulse-per-second signal from the navigation satellite system and a time service data packet and transmit the pulse-per-second signal to the SMU processor module. The SMU processor module is configured to: generating satellite local crystal oscillator clock time based on an oscillation signal of the crystal oscillator; determining first time information corresponding to the second pulse signal according to the clock time of the crystal oscillator; acquiring a time service data packet corresponding to the second pulse signal, and determining second time information corresponding to the second pulse signal according to the acquired time service data packet; and determining a time deviation value of the time of the crystal oscillator clock according to the first time information and the second time information.
According to another aspect of the present application, there is provided a time alignment method for a satellite, comprising: generating satellite local crystal oscillator clock time based on an oscillation signal of the crystal oscillator; receiving a pulse-per-second signal and a time service data packet from a navigation satellite system; determining first time information corresponding to the second pulse signal according to the clock time of the crystal oscillator; acquiring a time service data packet corresponding to the second pulse signal, and determining second time information corresponding to the second pulse signal according to the acquired time service data packet; and determining a time deviation value of the time of the crystal oscillator clock according to the first time information and the second time information.
According to the technical scheme of the embodiment of the disclosure, unlike the prior art that the time error is determined by calculating the phase difference according to the PPS second pulse signal obtained from the navigation satellite system and the PPS second pulse signal generated by the real-time clock module, the technical scheme disclosed in the embodiment directly calculates the time offset value by using the reference time (the second time information corresponding to the PPS signal) determined according to the time service data packet received by the navigation satellite system module and the crystal oscillator clock time (the first time information corresponding to the PPS) corresponding to the PPS second pulse signal collected by the real-time clock module. Therefore, the technical scheme disclosed by the embodiment can achieve the technical effects of simplifying the time calibration process and reducing the time cost of calibration. The technical problems that in the prior art, the process of calculating the time deviation value by utilizing the phase difference between the PPS signal of the GNSS system and the PPS signal generated by the real-time clock module is complicated and the time cost is high are solved.
The above, as well as additional objectives, advantages, and features of the present application will become apparent to those skilled in the art from the following detailed description of a specific embodiment of the present application when read in conjunction with the accompanying drawings.
Drawings
Some specific embodiments of the application will be described in detail hereinafter by way of example and not by way of limitation with reference to the accompanying drawings. The same reference numbers will be used throughout the drawings to refer to the same or like parts or portions. It will be appreciated by those skilled in the art that the drawings are not necessarily drawn to scale. In the accompanying drawings:
FIG. 1 is a schematic diagram of a time alignment system for satellites according to one embodiment of the application;
FIG. 2 is a schematic diagram of a connection structure of a processor module and a real-time clock module according to one embodiment of the application;
FIG. 3A is a schematic diagram schematically showing the relationship between PPS second pulse signal and crystal oscillator clock time;
Fig. 3B schematically illustrates a PPS second pulse signal and a GPIO interrupt signal;
FIG. 4 is a schematic diagram of a real-time clock acquisition unit with two crystal oscillator clock units according to one embodiment of the application;
FIG. 5 is a flow chart of a method for time alignment of satellites according to another aspect of an embodiment of the application; and
Fig. 6 is a flowchart of a method for satellite real-time calibration according to another embodiment of the application.
Detailed Description
It should be noted that, without conflict, the embodiments of the present disclosure and features of the embodiments may be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
In order that those skilled in the art will better understand the present disclosure, a technical solution in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present disclosure, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without inventive effort, based on the embodiments in this disclosure, shall fall within the scope of the present disclosure.
It should be noted that the terms "first," "second," and the like in the description and claims of the present disclosure and in the foregoing figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the disclosure described herein are, for example, capable of operation in connection with other embodiments. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
FIG. 1 is a schematic diagram of a time alignment system for satellites according to one embodiment of the application; fig. 2 is a schematic diagram of a connection structure of the processor module 110 and the real-time clock module 120 according to an embodiment of the present application. Referring to fig. 1 and 2, a time alignment system for a satellite includes: the system comprises an SMU processor module 100 and a navigation satellite system module 200 communicatively coupled to the SMU processor module 100, wherein the navigation satellite system module 200 is configured to receive a pulse-per-second signal from the navigation satellite system and time service data packets and to transmit the pulse-per-second signal to the SMU processor module 100. Wherein the SMU processor module 100 is configured to: generating satellite local crystal oscillator clock time based on the oscillation signal of the crystal oscillator 130; determining first time information corresponding to the second pulse signal according to the clock time of the crystal oscillator; acquiring a time service data packet corresponding to the second pulse signal, and determining second time information corresponding to the second pulse signal according to the acquired time service data packet; and determining a time deviation value of the time of the crystal oscillator clock according to the first time information and the second time information.
Referring specifically to fig. 1 and 2, SMU processor module 100 includes a real-time clock module 120 and a processor module 110. The navigation satellite system module 200 is communicatively connected to the real-time clock module 120, the real-time clock module 120 is communicatively connected to the processor module 110, and the navigation satellite system module 200 is communicatively connected to the processor module 110. The navigation satellite system module 200 is configured to receive PPS second pulse signals and time service data packets from the navigation satellite system. The navigation satellite system may be, for example, a GPS system, the PPS pulse-per-second signal may be, for example, a pulse-per-second signal transmitted by the GPS system, and the time service data packet may be, for example, a GPS data packet corresponding to the PPS pulse-per-second signal.
And, the real-time clock module 120 includes a real-time clock acquisition unit 121 and a crystal oscillator clock unit 122. The crystal oscillator clock unit 122 is connected to the crystal oscillator 130, and is configured to generate a satellite local crystal oscillator clock time based on an oscillation signal of the crystal oscillator 130. The real-time clock acquisition unit 121 is communicatively connected to the navigation satellite system module 200, and configured to trigger the crystal oscillator clock unit 122 to store the crystal oscillator clock time (i.e., the first time information) corresponding to the PPS second pulse signal according to the PPS second pulse signal.
As shown in fig. 3A, the real-time clock acquisition unit 121 extracts the leading edge of the PPS second pulse signal, and for the leading edge of the PPS second pulse signal, triggers the crystal clock unit 122 to lock the crystal clock time (i.e., the first time information) corresponding to the leading edge, for example,
Then, the navigation satellite system module 200 acquires a time service data packet corresponding to the PPS second pulse signal, and transmits the time service data packet to the time management unit 112. The time management unit 112 reads the time corresponding to the PPS second pulse signal from the time service packet, and determines a reference time (i.e., second time information) for performing timing based on the read time. For example, the reference time corresponding to the leading edge of each PPS second pulse is
Then, the time management unit 112 compares the crystal oscillator clock time corresponding to the second pulse PPS with the reference time, thereby obtaining a time deviation value of the crystal oscillator clock time of the crystal oscillator clock unit 122 with respect to the reference time.
Finally, the time management unit may transmit the time deviation value to the crystal oscillator clock unit 122, so that the crystal oscillator clock unit 122 may correct the crystal oscillator clock time according to the time deviation value. Specifically, after obtaining the time deviation value, the time management unit 112 subtracts the time deviation value from the crystal oscillator clock time to obtain a corrected crystal oscillator clock time, and then updates and calibrates the crystal oscillator clock by using the corrected crystal oscillator clock time.
As can be seen from the above, unlike the prior art in which the time error is determined by calculating the phase difference from the PPS second pulse signal acquired by the navigation satellite system module 200 and the PPS second pulse signal generated by the real-time clock module 120, the technical solution disclosed in this embodiment is to directly calculate the time error value by using the reference time (the second time information corresponding to the PPS signal) determined from the time service data packet received by the navigation satellite system module 200 and the crystal oscillator clock time (the first time information corresponding to the PPS) acquired by the real-time clock module 120 and corresponding to the PPS second pulse signal. Therefore, the technical scheme disclosed by the embodiment can achieve the technical effects of simplifying the time calibration process and reducing the time cost of calibration. The technical problems that in the prior art, the process of calculating the time deviation value by utilizing the PPS signal of the GNSS system and the PPS signal generated by the real-time clock module is complex and the time cost is high are solved.
Preferably, the navigation satellite system module 200 is a GNSS module, and the interrupt processing unit 111 is a GPIO interrupt processing unit.
Optionally, the processor module 110 further includes: a bus management unit 113 communicatively connected to the navigation satellite system module 200, wherein the bus management unit 113 is configured to: transmitting a request for acquiring a time service data packet to the navigation satellite system module 200 through a preset bus; acquiring a time service data packet from the navigation satellite system module 200 through a preset bus; and sends the time service data packet to the time management unit 112. Preferably, the predefined bus may be a CAN bus, for example.
In particular, referring to fig. 1 and 2, the processor module 110 further includes a bus management unit 113. First, the bus management unit 113 may transmit a request for acquiring a time service data packet to the navigation satellite system module 200 through the CAN bus. Then, the navigation satellite system module 200 receives the request for acquiring the time service data packet sent by the bus management unit 113, and sends the time service data packet to the bus management unit 113 through the CAN bus. Finally, the bus management unit 113 transmits the received time service data packet to the time management unit 112. Therefore, the time service data packet corresponding to the PPS second pulse signal CAN be rapidly acquired through the CAN bus, and the speed and the efficiency of the calibration time are improved.
Optionally, the real-time clock module 120 further includes: and a real-time clock acquisition unit 121, wherein the real-time clock acquisition unit 121 is connected to the navigation satellite system module 200, and is configured to receive the second pulse signal generated by the navigation satellite system module 200 and generate an interrupt signal according to the second pulse signal.
Specifically, referring to fig. 1 and 2, the real-time clock module 120 further includes a real-time clock acquisition unit 121. The real-time clock acquisition unit 121 is connected to the navigation satellite system module 200. The navigation satellite system module 200 transmits PPS second pulse signals to the real-time clock module 120. The real-time clock module 120 receives the PPS second pulse signal transmitted by the navigation satellite system module 200 and generates an interrupt signal according to the PPS second pulse signal. The interrupt signal may be a GPIO interrupt signal. Wherein fig. 3B shows a schematic diagram of a GPIO interrupt signal corresponding to a PPS second pulse signal.
That is, the navigation satellite system module 200 transmits the PPS second pulse signal to the real-time clock acquisition unit 121 of the real-time clock module 120. The real-time clock acquisition unit 121 generates a GPIO interrupt signal according to the PPS second pulse signal and transmits the GPIO interrupt signal to the GPIO interrupt processing unit 111 of the processor module 110. Therefore, through the above arrangement, the processor module 110 can synchronously acquire the crystal oscillator clock time and the corresponding time service data packet while the real-time clock module 120 stores the crystal oscillator clock time corresponding to the PPS second pulse signal, so that the crystal oscillator clock time and the time service data packet can be accurately corresponding, and the accuracy of the calibration time is improved, and the efficiency of the calibration time is improved.
Optionally, the processor module 110 further includes: an interrupt processing unit 111 communicatively coupled to the real-time clock acquisition unit 121, wherein the interrupt processing unit 111 is configured to: receiving an interrupt signal; based on the interrupt signal, triggering the bus management unit 113 to transmit a request for acquiring a time service data packet to the navigation satellite system module 200; and based on the interrupt signal, triggering the time management unit 112 to send a request to the crystal oscillator clock unit 122 to acquire the first time information.
In particular, referring to fig. 1 and 2, the processor module 110 further includes an interrupt handling unit 111. The interrupt processing unit 111 receives an interrupt signal (i.e., GPIO interrupt signal) transmitted by the real-time clock acquisition unit 121. Then, the interrupt processing unit 111, upon receiving the interrupt signal, transmits a corresponding trigger instruction to the bus management unit 113 in response to the interrupt signal. So that the bus management unit 113 transmits a request for acquiring a time service data packet (i.e., a request for acquiring a GPS data packet through the CAN bus) to the navigation satellite system module 200 upon receiving the trigger instruction. In response to the interrupt signal, the terminal processing unit 111 also transmits a corresponding trigger instruction to the time management unit 112, so that the time management unit 112 transmits a request for acquiring the crystal clock time (i.e., the first time information) corresponding to the PPS second pulse signal to the crystal clock unit 122 according to the trigger instruction.
Alternatively, referring to fig. 4, the crystal oscillator 130 includes a first crystal oscillator 130a and a second crystal oscillator 130b, and the crystal oscillator clock unit 122 includes a first crystal oscillator clock unit 122a and a second crystal oscillator clock unit 122b. Thus, the satellite may provide a crystal clock time local to the satellite through the two crystal clocks 130a and 130b and the two crystal clock units 122a and 122b. The accuracy of satellite local timing is improved. The specific contents of the first and second crystals 130a and 130b, and the first and second crystal clock units 122a and 122b will be described in detail later.
According to another aspect of the present embodiment, there is provided a time alignment method for a satellite, wherein fig. 5 shows a flowchart of the method, and with reference to fig. 5, the method comprises:
s502: generating satellite local crystal oscillator clock time based on an oscillation signal of the crystal oscillator;
s504: receiving a pulse-per-second signal and a time service data packet from a navigation satellite system;
S506: determining first time information corresponding to the second pulse signal according to the clock time of the crystal oscillator;
s508: acquiring a time service data packet corresponding to the second pulse signal, and determining second time information corresponding to the second pulse signal according to the acquired time service data packet; and
S510: and determining a time deviation value of the time of the crystal oscillator clock according to the first time information and the second time information.
For the specific process of the method, reference may be made to the flow described in the first aspect of the present embodiment, which is not repeated here. Fig. 6 is a flow chart of a method for a satellite time calibration system according to the present embodiment.
Referring to fig. 6, the method in this embodiment includes the following steps:
s202: the navigation satellite system module 200 transmits PPS second pulse signals to the real-time clock acquisition unit 121 and the crystal oscillator clock unit 122 in the real-time clock module 120;
s204: the real-time clock acquisition unit 121 generates an interrupt signal (GPIO interrupt signal) according to the PPS second pulse signal, and transmits the interrupt signal to the interrupt processing unit 111 of the processor module 110;
s206: after the crystal oscillator clock unit 122 receives the PPS second pulse signal, the crystal oscillator clock time (i.e., the first time information) corresponding to the second pulse signal is collected;
S208: the interrupt processing unit 111 receives the interrupt signal transmitted by the real-time clock acquisition unit 121, and triggers the time management unit 112 and the bus management unit 113 in response to the interrupt signal;
S210: the time management unit 112 sends a request for acquiring the time of the crystal oscillator clock to the crystal oscillator clock unit 122;
s212: after receiving the request sent by the time management unit 112, the crystal oscillator clock unit 122 sends the crystal oscillator clock time (i.e., the first time information) to the time management unit 112;
S214: the bus management unit 113 sends a request for acquiring a time service data packet to the navigation satellite system module 200, wherein the time service data packet is a GPS data packet;
S216: after receiving the request for acquiring the time service data packet, the navigation satellite system module 200 puts the time service data packet to the bus management unit 113 through the CAN bus;
S218: bus management section 113 transmits the time service packet to time management section 112;
S220: the time management unit 112 determines a reference time (i.e., second time information) corresponding to each PPS second pulse according to the time service data packet, compares the reference time with a crystal oscillator clock time corresponding to each PPS second pulse, and calculates a time deviation value;
s222: the time management unit 112 sends the time deviation value to the crystal oscillator clock unit, and the crystal oscillator clock unit calibrates the crystal oscillator clock according to the time deviation value.
According to the technical scheme of the embodiment of the disclosure, unlike the prior art that the time error is determined by calculating the phase difference according to the PPS second pulse signal obtained from the navigation satellite system and the PPS second pulse signal generated by the real-time clock module, the technical scheme disclosed in the embodiment directly calculates the time offset value by using the reference time (the second time information corresponding to the PPS signal) determined according to the time service data packet received by the navigation satellite system module and the crystal oscillator clock time (the first time information corresponding to the PPS) corresponding to the PPS second pulse signal collected by the real-time clock module. Therefore, the technical scheme disclosed by the embodiment can achieve the technical effects of simplifying the time calibration process and reducing the time cost of calibration. The technical problems that in the prior art, the process of calculating the time deviation value by utilizing the PPS signal of the GNSS system and the PPS signal generated by the real-time clock module is complex and the time cost is high are solved.
Further alternatively, generating satellite local crystal oscillator clock time based on the crystal oscillator oscillation signal includes: generating a satellite local first crystal oscillator clock time based on an oscillation signal of the first crystal oscillator; and generating a second crystal clock time local to the satellite based on the oscillating signal of the second crystal. And determining first time information corresponding to the second pulse signal according to the crystal oscillator clock time, comprising: and respectively determining first time information corresponding to the second pulse signal according to the first crystal oscillator clock time and the second crystal oscillator clock time.
Specifically, the technical scheme of the invention also relates to correction for the accuracy of the crystal oscillator clock. According to the research of the inventor, the accuracy and stability of the crystal oscillator clock are mainly influenced by two factors. The first factor is the influence of the aging degree of the crystal oscillator; the second factor is the effect of the change in the ambient temperature to which the crystal is exposed. The frequency characteristic of the crystal oscillator is shifted along with time due to the influence of the aging degree, so that the time error is gradually increased along with time after the crystal oscillator clock is electrified. In addition, the stability of the crystal oscillator is also affected by the ambient temperature, and since the crystal oscillator is usually arranged in a constant-temperature environment (such as a constant-temperature tank) in the prior art, the influence of temperature change on the accuracy of the crystal oscillator clock has the characteristic of conforming to the normal distribution (0, sigma).
In order to overcome the defects of the crystal oscillator clock and enable the satellite to better realize self-time keeping at the moment between two GNSS time correction, the technical scheme of the invention provides a technical scheme for jointly timing the application process on the satellite by utilizing the two crystal oscillator clocks. Referring to fig. 4, the crystal oscillator 130 includes a first crystal oscillator 130a and a second crystal oscillator 130b, and the crystal oscillator clock unit 122 includes a first crystal oscillator clock unit 122a and a second crystal oscillator clock unit 122b. Thus, the satellite may provide a crystal clock time local to the satellite through the two crystal clocks 130a and 130b and the two crystal clock units 122a and 122b.
Then, according to the technical solution of the present disclosure, the satellite may periodically (for example, once a day, or once every two days) turn on the GNSS timing function, and determine the error information of the first crystal oscillator clock unit 122a and the second crystal oscillator clock unit 122b through PPS second pulses and time service data packets provided by the GNSS.
Then, the GPIO interrupt processing unit 111 triggers the time management unit 112 to acquire the first crystal oscillator clock time and the second crystal oscillator clock time of the first crystal oscillator clock unit 122a and the second crystal oscillator clock unit 122b corresponding to the PPS second pulse from the first crystal oscillator clock unit 122a and the second crystal oscillator clock unit 122b in response to the GPIO interrupt corresponding to the PPS second pulse. The GNSS module 200 acquires a GPS packet corresponding to the PPS second pulse, acquires a time service time corresponding to the PPS second pulse from the GPS packet, and determines a reference time corresponding to the PPS second pulse according to the time service time.
Specifically, the GPIO interrupt processing unit 111 of the processor module 110 may, for example, trigger the time management unit 112 to obtain the first crystal oscillator clock time T 1,0～t1,m output by the first crystal oscillator clock unit 122a and the second crystal oscillator clock time T 2,0～t2,m output by the second crystal oscillator clock unit 122b at a plurality of measurement moments 0-m according to a preset time interval Δt (i.e., a preset number of GPIO interrupt signals) according to the GPIO interrupt signals corresponding to PPS pulses. The GPIO interrupt processing unit 111 also acquires satellite time service times from the GNSS module 200 at a plurality of measurement times 0 to m via the bus management unit 113, and determines a reference time t 0～tm corresponding to each measurement time 0 to m based on the satellite time service times. The specific table is shown below:
TABLE 1
| Measuring time of day | 0 | 1 | 2 | 3 | 4 | .... | m |
| Reference time | t0 | t1 | t2 | t3 | t4 | .... | tm |
| First crystal oscillator clock time | t1,0 | t1,1 | t1,2 | t1,3 | t1,4 | .... | t1,m |
| Second crystal oscillator clock time | t2,0 | t2,1 | t2,2 | t2,3 | t2,4 | .... | t2,m |
The reference time t 0～tm may be determined, for example, according to the method described above, based on the satellite time acquired from the GPS packet.
In addition, the first crystal oscillator clock unit 122a outputs a crystal oscillator clock time t 1,0 at time 0 determined according to the GPIO interrupt signal; the time of the crystal oscillator clock output at the time 1 determined according to the GPIO interrupt signal is t 1,1; the time of the crystal oscillator clock output at the moment 2 determined according to the GPIO interrupt signal is t 1,2; ... The crystal oscillator clock time output at the time m determined according to the GPIO interrupt signal is t 1,m.
Wherein, the crystal oscillator clock time output by the second crystal oscillator clock unit 122a at the time 0 determined according to the GPIO interrupt signal is t 2,0; the time of the crystal oscillator clock output at the time 1 determined according to the GPIO interrupt signal is t 2,1; the time of the crystal oscillator clock output at the moment 2 determined according to the GPIO interrupt signal is t 2,2; ... The crystal oscillator clock time output at the time m determined according to the GPIO interrupt signal is t 2,m.
Optionally, the operation of determining the time deviation value of the crystal oscillator clock time according to the first time information and the second time information includes: and determining time deviation values and deviation variances of the first crystal oscillator clock time and the second crystal oscillator clock time according to the first time information and the second time information, wherein the deviation variances are used for indicating the distribution condition of the time deviation values of the first crystal oscillator clock time and the second crystal oscillator clock time relative to the second time information. And the method further comprises: calibrating the first crystal oscillator clock time and the second crystal oscillator clock time by using the time offset value
Specifically, the time management unit 112 determines the time deviation Δt 1,0～Δt1,m of the first crystal oscillator clock time t 1,0～t1,m output by the first crystal oscillator clock unit 122a from the reference time t 0～tm at the time instants 0 to m according to the following formula (1) according to the first crystal oscillator clock time t 1,0～t1,m output by the first crystal oscillator clock unit 122a and the corresponding reference time t 0～tm:
Δt1,i＝t1,i-ti (1)
Wherein i=0 to m.
As shown in table 2 below:
TABLE 2
Meanwhile, the time management unit 112 determines the time deviation Δt 2,0～Δt2,m of the crystal oscillator clock time t 2,0～t2,m output by the second crystal oscillator clock unit 122b with respect to the reference time t 0～tm at the time 0 to m according to the following formula (2) according to the crystal oscillator clock time t 2,0～t2,m output by the second crystal oscillator clock unit 122b and the corresponding reference time t 0～tm:
Δt2,i＝t2,i-ti (2)
Wherein i=0 to m.
As shown in table 3 below:
TABLE 3 Table 3
Then, the time management unit 112 calculates the corresponding deviation mean μ 1 and deviation variance σ 1 according to the following formula from the time deviation Δt 1,0～Δt1,m of the first crystal oscillator clock unit 122 a.
And, the time management unit 112 calculates the corresponding deviation mean μ 2 and deviation variance σ 2 according to the following formula from the time deviation Δt 2,0～Δt2,m of the second crystal clock unit 122 b.
So that the mean value of the deviation and the deviation method of the first crystal oscillator clock unit 122a and the second crystal oscillator clock unit 122b can be determined in the above manner. Wherein the mean value of the deviation can reflect the error of the first crystal oscillator clock unit 122a and the second crystal oscillator clock unit 122b at the current moment due to aging. The variance of the deviation can reflect random errors of the first and second crystal clock units 122a and 122b due to the ambient temperature.
Then, the time management unit 112 corrects the first crystal oscillator clock time tcur 1 acquired from the first crystal oscillator clock unit 122a and the second crystal oscillator clock time tcur 2 acquired from the second crystal oscillator clock unit 122b to obtain a first correction time tcrt 1 corresponding to the first crystal oscillator clock time tcur 1 and a second correction time tcrt 2 corresponding to the second crystal oscillator clock time according to the following formula:
tcrt1＝tcur1-μ1 (7)
tcrt2＝tcur2-μ2 (8)
Then, the first crystal oscillator clock unit 122a performs calibration with the first calibration time tcrt 1 and the second crystal oscillator clock unit 122b performs calibration with the second calibration time tcrt 2, thereby completing the GNSS timing function. In this way, the measurement errors due to frequency drift caused by crystal oscillator aging can be corrected by performing GNSS calibration periodically. And the deviation variance of the crystal oscillator clock unit can be continuously updated, so that more accurate deviation variance is obtained.
Further optionally, the method further comprises: and determining the time corresponding to the target event according to the corrected first crystal oscillator clock time, the corrected second crystal oscillator clock time, the deviation variance of the first crystal oscillator clock time and the deviation variance of the second crystal oscillator clock time.
Specifically, when the SMU processor module 100 needs to determine a time corresponding to a target event for processing the target event, for example, when the SMU processor module 100 needs to send telemetry data to a surface system, a timestamp corresponding to the task needs to be determined.
The time management unit 112 may read the GNSS-calibrated first crystal clock time tobj 1 corresponding to the current time related to the target event from the first crystal clock unit 122a and the GNSS-calibrated second crystal clock time tobj 2 corresponding to the current time from the second crystal clock unit 122 b.
The time management unit 112 then determines a time value tobj associated with the target event according to the following formula:
tobj＝tobj1+k*(tobj2-tobj1) (9)
The time management unit 112 then regards the calculated final time value tobj as the time corresponding to the target event. The time value tobj is thus more accurate than the GNSS calibrated first crystal clock time tobj 1 and the GNSS calibrated second crystal clock time tobj 2. Therefore, by means of the method, the two crystal oscillator clocks are used for fusing measurement results, and random errors of the crystal oscillator clocks due to environmental temperature changes can be effectively reduced.
Therefore, the technical scheme of the invention can effectively reduce the measurement error generated by the frequency drift of the crystal oscillator clock unit due to crystal oscillator aging by carrying out GNSS calibration on the crystal oscillator clock unit at regular intervals. And the offset value and the offset variance of the crystal oscillator clock unit can be updated continuously through GNSS calibration, so that the calculated offset variance of the crystal oscillator clock unit can be updated continuously along with the GNSS calibration, and the method is more accurate. In addition, the time measurement results are fused based on the deviation variance by utilizing the plurality of crystal oscillator clock units, so that random errors of the crystal oscillator clock due to environmental temperature change can be effectively reduced.
The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless it is specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective parts shown in the drawings are not drawn in actual scale for convenience of description. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
Spatially relative terms, such as "above … …," "above … …," "upper surface on … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial location relative to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations "above … …" and "below … …". The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
In the description of the present disclosure, it should be understood that the azimuth or positional relationships indicated by the azimuth terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal", and "top, bottom", etc., are generally based on the azimuth or positional relationships shown in the drawings, merely to facilitate description of the present disclosure and to simplify the description, and these azimuth terms do not indicate and imply that the apparatus or elements referred to must have a specific azimuth or be configured and operated in a specific azimuth, and thus should not be construed as limiting the scope of protection of the present disclosure; the orientation word "inner and outer" refers to inner and outer relative to the contour of the respective component itself.
The present application is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present application are intended to be included in the scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims (8)
1. A time alignment system for a satellite, comprising: -an SMU processor module (100) and-a navigation satellite system module (200) communicatively connected to the SMU processor module (100), wherein the navigation satellite system module (200) is configured to receive a pulse-per-second signal from a navigation satellite system and time service data packets and to transmit the pulse-per-second signal to the SMU processor module (100), characterized in that the SMU processor module (100) is configured to:
generating a satellite local crystal oscillator clock time based on an oscillation signal of the crystal oscillator (130);
determining first time information corresponding to the second pulse signal according to the crystal oscillator clock time;
acquiring a time service data packet corresponding to the second pulse signal, and determining second time information corresponding to the second pulse signal according to the acquired time service data packet; and
Determining a time deviation value of the crystal oscillator clock time according to the first time information and the second time information, wherein
An operation of generating a satellite local crystal oscillator clock time based on an oscillation signal of a crystal oscillator, comprising:
generating a satellite local first crystal oscillator clock time based on an oscillation signal of the first crystal oscillator; and
Generating a second crystal clock time local to the satellite based on the oscillating signal of the second crystal, and wherein
The operation of determining the first time information corresponding to the second pulse signal according to the crystal oscillator clock time comprises the following steps: determining first time information corresponding to the second pulse signal according to the first crystal oscillator clock time and the second crystal oscillator clock time respectively, and wherein
The operation of determining the time deviation value of the crystal oscillator clock time according to the first time information and the second time information comprises the following steps: determining a time deviation value and a deviation variance of the first crystal oscillator clock time and the second crystal oscillator clock time according to the first time information and the second time information, wherein the deviation variance is used for indicating the distribution condition of the time deviation value of the first crystal oscillator clock time and the second crystal oscillator clock time relative to the second time information, and the method further comprises the following steps:
And calibrating the first crystal oscillator clock time and the second crystal oscillator clock time by using the time deviation value.
2. The system of claim 1, wherein the SMU processor module (100) includes a processor module (110) and a real-time clock module (120), the real-time clock module (120) including: a real time clock acquisition unit (121) and a crystal oscillator clock unit (122), the processor module (110) comprising: a time management unit (112), wherein
The crystal oscillator clock unit (122) is connected with the crystal oscillator (130) and is used for generating the crystal oscillator clock time based on an oscillation signal of the crystal oscillator (130); and
The real-time clock acquisition unit (121) is in communication connection with the navigation satellite system module (200) and is configured to trigger the crystal oscillator clock unit (122) to store the first time information according to the second pulse signal.
3. The system of claim 2, wherein the processor module (110) further comprises a bus management unit (113) communicatively connected to the navigation satellite system module (200), wherein the bus management unit (113) is configured to:
Transmitting a request for acquiring the time service data packet to the navigation satellite system module (200) through a preset bus;
Acquiring the time service data packet from the navigation satellite system module (200) through the preset bus; and
-Sending the time service data packet to the time management unit (112).
4. A system according to claim 3, wherein the real time clock module (120) further comprises: a real-time clock acquisition unit (121), wherein
The real-time clock acquisition unit (121) is connected with the navigation satellite system module (200), and is configured to receive the pulse-per-second signal from the navigation satellite system module (200) and generate a corresponding interrupt signal according to the pulse-per-second signal.
5. The system of claim 4, wherein the processor module (110) further comprises: an interrupt handling unit (111) in communication with the real time clock acquisition unit (121), wherein the interrupt handling unit (111) is configured to:
Receiving the interrupt signal;
Based on the interrupt signal, triggering the bus management unit (113) to send a request for acquiring the time service data packet to the navigation satellite system module (200); and
Based on the interrupt signal, the time management unit (112) is triggered to send a request for acquiring the first time information to the crystal oscillator clock unit (122).
6. The system of claim 5, wherein the crystal oscillator (130) comprises a first crystal oscillator (130 a) and a second crystal oscillator (130 b), and the crystal oscillator clock unit (122) comprises a first crystal oscillator clock unit (122 a) and a second crystal oscillator clock unit (122 b).
7. A time alignment method for a satellite, comprising:
generating satellite local crystal oscillator clock time based on an oscillation signal of the crystal oscillator;
receiving a pulse-per-second signal and a time service data packet from a navigation satellite system;
determining first time information corresponding to the second pulse signal according to the crystal oscillator clock time;
acquiring a time service data packet corresponding to the second pulse signal, and determining second time information corresponding to the second pulse signal according to the acquired time service data packet; and
Determining a time deviation value of the crystal oscillator clock time according to the first time information and the second time information, wherein
An operation of generating a satellite local crystal oscillator clock time based on an oscillation signal of a crystal oscillator, comprising:
generating a satellite local first crystal oscillator clock time based on an oscillation signal of the first crystal oscillator; and
Generating a second crystal clock time local to the satellite based on the oscillating signal of the second crystal, and wherein
The operation of determining the first time information corresponding to the second pulse signal according to the crystal oscillator clock time comprises the following steps: determining first time information corresponding to the second pulse signal according to the first crystal oscillator clock time and the second crystal oscillator clock time respectively, and wherein
The operation of determining the time deviation value of the crystal oscillator clock time according to the first time information and the second time information comprises the following steps: determining a time deviation value and a deviation variance of the first crystal oscillator clock time and the second crystal oscillator clock time according to the first time information and the second time information, wherein the deviation variance is used for indicating the distribution condition of the time deviation value of the first crystal oscillator clock time and the second crystal oscillator clock time relative to the second time information, and the method further comprises:
And calibrating the first crystal oscillator clock time and the second crystal oscillator clock time by using the time deviation value.
8. The method of claim 7, further comprising determining a time corresponding to a target event based on the calibrated first crystal oscillator clock time, the calibrated second crystal oscillator clock time, a variance of the first crystal oscillator clock time, and a variance of the second crystal oscillator clock time.
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