阅读说明：本技术 一种基于卫星授时的守时方法及系统 (Satellite time service-based time keeping method and system ) 是由 李文婷 李莹莹 焦名 殷勤 郭军强 于 2019-10-17 设计创作，主要内容包括：本发明属于通信技术领域,特别涉及一种基于卫星授时的守时方法及系统。所述守时方法包括：获取卫星时间,判断所述卫星时间是否异常；若所述卫星时间正常,则输出所述卫星时间；若所述卫星时间异常,则判断所述卫星时间是否可信；若所述卫星时间可信,则输出所述卫星时间；若所述卫星时间不可信,则获取并输出守时时间。本发明采用UTC时间与系统内部时钟融合的方法,保证系统内部时间的准确性,确保系统在通信过程中具有时效性。(The invention belongs to the technical field of communication, and particularly relates to a time keeping method and system based on satellite time service. The time keeping method comprises the following steps: acquiring satellite time, and judging whether the satellite time is abnormal or not; if the satellite time is normal, outputting the satellite time; if the satellite time is abnormal, judging whether the satellite time is credible; if the satellite time is credible, outputting the satellite time; and if the satellite time is not credible, acquiring and outputting the time keeping time. The invention adopts the method of fusing the UTC time and the system internal clock, thereby ensuring the accuracy of the system internal time and ensuring the timeliness of the system in the communication process.)

1. A time keeping method based on satellite time service is characterized by comprising the following steps:

acquiring satellite time, and judging whether the satellite time is abnormal or not;

if the satellite time is normal, outputting the satellite time;

if the satellite time is abnormal, judging whether the satellite time is credible;

if the satellite time is credible, outputting the satellite time;

and if the satellite time is not credible, acquiring and outputting the time keeping time.

2. The time keeping method of claim 1,

the satellite time acquisition refers to the satellite time transmitted by the time service satellite.

3. The time keeping method according to claim 1 or 2,

judging whether the satellite time is abnormal comprises the following steps:

acquiring satellite time of the period and output time of the previous period;

if the satellite time is later than the output time, the satellite time is normal;

and if the satellite time is not later than the output time, the satellite time is abnormal.

4. The time keeping method of claim 3,

determining whether the satellite time is authentic comprises:

acquiring time information of a plurality of continuous periods; wherein the plurality of continuous periods include a last period of a current determination time point; the time information comprises satellite time and CTC system time acquired in a corresponding period;

respectively subtracting the CTC system time from the satellite time in the corresponding period to obtain a difference value;

if the absolute values of all the difference values are within a preset value range, the satellite time is credible;

otherwise the satellite time is not trusted.

5. The time keeping method of claim 1,

the acquiring the timekeeping time comprises:

acquiring the output time of the previous period;

acquiring the system cycle time of the previous cycle and the system cycle time of the current cycle;

subtracting the system cycle time of the previous cycle from the system cycle time of the current cycle to obtain a system cycle time difference;

and adding the system period time difference to the output time of the previous period to obtain the timekeeping time.

6. The time keeping method of claim 1 or 4,

the time keeping method further comprises the following steps:

if the acquired satellite time is not credible, the system initialization fails, and an all-zero value is output;

and re-acquiring and judging whether the new satellite time is credible.

7. A time keeping system based on satellite time service is characterized in that the time keeping system comprises:

the first judgment unit is used for acquiring satellite time and CTC system time and judging the credibility of the satellite time;

the second judgment unit is used for acquiring satellite time and judging whether the satellite time is abnormal or not;

the real-time operation unit is used for acquiring and outputting satellite time;

and the time keeping operation unit is used for acquiring the system period time difference, and calculating and outputting the time keeping time according to the system period time difference.

8. The time keeping system of claim 7, further comprising:

a satellite time acquisition unit for acquiring and transmitting satellite time;

the CTC system clock is used for transmitting the CTC system time;

and the periodic clock is used for generating system periodic time, and calculating and sending a system periodic time difference according to the system periodic time.

9. The time keeping system of claim 8,

the satellite time acquisition unit acquires satellite time sent by a time service satellite and sends the satellite time to the first judgment unit; the CTC system clock sends the CTC system time to a first judgment unit;

the first judging unit receives and judges whether the satellite time is credible or not according to the satellite time and the CTC system time;

if the satellite time is credible, the system is initialized successfully, at the moment, the first judgment unit sends the satellite time to a real-time operation unit, and the real-time operation unit acquires and outputs the satellite time;

if the satellite time is not credible, the system initialization fails, and at the moment, the first judging unit acquires new satellite time again to judge the credibility until the system initialization is successful.

10. The time keeping system of claim 9,

after the system is initialized successfully, the satellite time acquisition unit continues to acquire new satellite time;

the second judging unit acquires the new satellite time and judges whether the new satellite time is abnormal or not;

if the new satellite time is normal, sending the new satellite time to a real-time operation unit, and acquiring and outputting the new satellite time by the real-time operation unit;

if the new satellite time is abnormal, the new satellite time is sent to a first judgment unit for credibility judgment;

the first judging unit acquires the new satellite time, acquires new CTC system time sent by a CTC system clock, and judges the credibility of the new satellite time according to the new satellite time and the new CTC system time;

if the new satellite time is credible, sending the new satellite time to a real-time operation unit, and acquiring and outputting the new satellite time by the real-time operation unit;

and if the new satellite time is not credible, controlling the timekeeping operation unit to acquire a system period time difference, and calculating and outputting the timekeeping time according to the system period time difference.

Technical Field

The invention belongs to the technical field of communication, and particularly relates to a time keeping method and system based on satellite time service.

Background

In a train operation control system, communication between ground equipment and vehicle-mounted equipment is required to have certain timeliness, a satellite time service technology is adopted, the same clock is arranged in the system, and the timeliness of the communication is judged by the aid of the unified clock. The data sent by the ground equipment to the vehicle-mounted equipment contains clock information, and the vehicle-mounted equipment analyzes the clock information in the data packet and judges whether the data meets the timeliness requirement of the system, so that whether the data is legally available is determined.

But only through satellite time service, provide the clock information for the check-up for the communication data, there is the drawback. For example, if the communication device cannot obtain accurate clock information due to a failure of the time service satellite or a communication failure between the time service satellite and the communication device, the normal transmission of data in the train operation control system may be affected.

Disclosure of Invention

Aiming at the problems, the invention provides a time keeping method based on satellite time service, which comprises the following steps:

acquiring satellite time, and judging whether the satellite time is abnormal or not;

if the satellite time is normal, outputting the satellite time;

if the satellite time is abnormal, judging whether the satellite time is credible;

if the satellite time is credible, outputting the satellite time;

and if the satellite time is not credible, acquiring and outputting the time keeping time.

Further, the acquiring of the satellite time refers to acquiring the satellite time transmitted by the time service satellite.

Further, determining whether the satellite time is abnormal includes:

acquiring satellite time of the period and output time of the previous period;

if the satellite time is later than the output time, the satellite time is normal;

and if the satellite time is not later than the output time, the satellite time is abnormal.

Further, determining whether the satellite time is authentic includes:

acquiring time information of a plurality of continuous periods; wherein the plurality of continuous periods include a last period of a current determination time point; the time information comprises satellite time and CTC system time acquired in a corresponding period;

respectively subtracting the CTC system time from the satellite time in the corresponding period to obtain a difference value;

if the absolute values of all the difference values are within a preset value range, the satellite time is credible;

otherwise the satellite time is not trusted.

Further, the acquiring the timekeeping time comprises:

acquiring the output time of the previous period;

acquiring the system cycle time of the previous cycle and the system cycle time of the current cycle;

subtracting the system cycle time of the previous cycle from the system cycle time of the current cycle to obtain a system cycle time difference;

and adding the system period time difference to the output time of the previous period to obtain the timekeeping time.

Further, the time keeping method further comprises the following steps:

if the acquired satellite time is not credible, the system initialization fails, and an all-zero value is output;

and re-acquiring and judging whether the new satellite time is credible.

The invention also provides a time keeping system based on satellite time service, which comprises:

the first judgment unit is used for acquiring satellite time and CTC system time and judging the credibility of the satellite time;

the second judgment unit is used for acquiring satellite time and judging whether the satellite time is abnormal or not;

the real-time operation unit is used for acquiring and outputting satellite time;

and the time keeping operation unit is used for acquiring the system period time difference, and calculating and outputting the time keeping time according to the system period time difference.

Further, the timekeeping system further comprises:

a satellite time acquisition unit for acquiring and transmitting satellite time;

the CTC system clock is used for transmitting the CTC system time;

and the periodic clock is used for generating system periodic time, and calculating and sending a system periodic time difference according to the system periodic time.

Further, the satellite time acquisition unit acquires satellite time sent by a time service satellite and sends the satellite time to the first judgment unit; the CTC system clock sends the CTC system time to a first judgment unit;

the first judging unit receives and judges whether the satellite time is credible or not according to the satellite time and the CTC system time;

if the satellite time is credible, the system is initialized successfully, at the moment, the first judgment unit sends the satellite time to a real-time operation unit, and the real-time operation unit acquires and outputs the satellite time;

if the satellite time is not credible, the system initialization fails, and at the moment, the first judging unit acquires new satellite time again to judge the credibility until the system initialization is successful.

Further, after the system is initialized successfully, the satellite time acquisition unit continues to acquire new satellite time;

the second judging unit acquires the new satellite time and judges whether the new satellite time is abnormal or not;

if the new satellite time is normal, sending the new satellite time to a real-time operation unit, and acquiring and outputting the new satellite time by the real-time operation unit;

if the new satellite time is abnormal, the new satellite time is sent to a first judgment unit for credibility judgment;

the first judging unit acquires the new satellite time, acquires new CTC system time sent by a CTC system clock, and judges the credibility of the new satellite time according to the new satellite time and the new CTC system time;

if the new satellite time is credible, sending the new satellite time to a real-time operation unit, and acquiring and outputting the new satellite time by the real-time operation unit;

and if the new satellite time is not credible, controlling the timekeeping operation unit to acquire a system period time difference, and calculating and outputting the timekeeping time according to the system period time difference.

The invention adopts the method of fusing the UTC time and the system internal clock, thereby ensuring the accuracy of the system internal time and ensuring the timeliness of the system in the communication process.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 shows a schematic diagram of a communication scenario according to an embodiment of the invention;

FIG. 2 illustrates a state transition diagram of a surface control apparatus according to an embodiment of the present invention;

FIG. 3 illustrates a process flow diagram in a device initialization state according to an embodiment of the invention;

FIG. 4 shows a process flow diagram in a real-time plant operating state according to an embodiment of the invention;

fig. 5 shows a flowchart of processing in the device time-keeping operation state according to the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the train operation control system, the communication between the ground equipment and the vehicle-mounted equipment is realized in a wireless communication mode. The ground equipment and the vehicle-mounted equipment need to have accurately synchronized clocks in order to ensure timeliness of communication.

According to the time keeping method based on satellite time service provided by the invention, exemplarily, as shown in fig. 1, a ground satellite time service receiving device establishes signal connection with a time service satellite, and the ground satellite time service receiving device receives a first satellite time (a first UTC time) sent by the time service satellite in real time; and the ground satellite time service receiving equipment sends the first satellite time to ground control equipment. The vehicle-mounted satellite time service receiving equipment establishes signal connection with the time service satellite, and receives second satellite time (second UTC time) sent by the time service satellite in real time; and the vehicle-mounted satellite time service receiving equipment sends the second satellite time to the vehicle-mounted equipment.

Further, the ground control equipment sends a ground data packet to the vehicle-mounted equipment, the ground data packet comprises first satellite time acquired by the ground control equipment, and the first satellite time is used for checking the timeliness of communication at the receiving end of the vehicle-mounted equipment. Specifically, the vehicle-mounted device compares and checks the first satellite time and the second satellite time in the ground data packet, and judges the specific sending time of the ground data packet.

Furthermore, the ground control equipment and the CTC system clock equipment in the railway dispatching set are in signal connection, and the ground control equipment can acquire CTC system time sent by the CTC system clock equipment in the railway dispatching set in each system period.

Further, the ground control device is provided with a periodic clock for generating a system period time, and calculating and transmitting a system period time difference according to the system period time.

The time keeping method proposed by the present invention is exemplified by taking the ground control device as an example, but the time keeping method is not limited to the ground control device, and the time keeping method is also applicable to other communication devices.

During the working process of the ground control equipment, the ground control equipment comprises the following working states:

an initialization state: the ground control equipment is communicated with the ground satellite time service receiving equipment, and the ground control equipment receives the satellite time sent by the ground satellite time service receiving equipment. Specifically, the ground satellite time service receiving equipment and the time service satellite establish signal connection, and acquire satellite time transmitted by the time service satellite.

Real-time running state: and the ground control equipment receives the satellite time from the ground satellite time service equipment in real time and outputs the satellite time.

The punctual operation state: when the ground control equipment cannot receive effective satellite time sent by the ground satellite time service equipment, adding the time output by the ground control equipment in the previous period to the system period time difference calculated by the period clock to be used as timekeeping time; and outputting the timekeeping time.

Illustratively, as shown in fig. 2, the time keeping method includes the steps of:

the method comprises the following steps: and carrying out initialization operation on the communication equipment.

Illustratively, initializing the surface control device includes: starting up or restarting the ground control equipment; after the ground control equipment is started, signal connection is established between the ground control equipment and ground satellite time service receiving equipment; the ground satellite time service receiving equipment sends the satellite time acquired from the time service satellite to ground control equipment; the ground control device receives the satellite time in real time.

Setting the time of one cycle output on the ground control equipment as a first output time timeOutold, and initializing the time to be a zero value;

setting the time output by the ground control equipment in the period as a second output time timeOutNew, and initializing the time to be a full zero value;

setting satellite time received from a ground satellite time service receiving device on a period of ground control equipment as first receiving time timeInOld, and initializing the satellite time to be a full zero value;

setting the satellite time received by the ground control equipment from the ground satellite time service receiving equipment in the period as a second receiving time timeInNew;

setting the time of receiving the clock from the CTC system in the current period of the ground control equipment as a third receiving time timeCTCN;

setting the cycle time of a cycle on a cycle clock in the ground control equipment as a first cycle time timeCycleOld;

and setting the cycle time of the cycle clock in the ground control equipment as second cycle time timecycle New.

Illustratively, as shown in fig. 3, in the initialization state, the process flow of the ground control device is as follows:

after the ground control equipment is started, signal connection is established with ground satellite time service receiving equipment, and satellite time sent by the ground satellite time service receiving equipment is received;

and judging whether the satellite time service is credible, namely judging whether the satellite time is credible.

For example, whether the satellite time service is trusted or not can be judged by comparing the time values of the second receiving time timelnnew and the third receiving time timecctnew in the initialization process. Specifically, in the device initialization process, N continuous system periods are determined, and the N system periods are the system periods closest to the current judgment operation time point; | time InNew_n–timeCTCNew_n|<Δ t, which is a constant representing a time length and is a preset value; n represents indexes of different periods in N continuous system periods, if the inequality condition is satisfied, the satellite time service is credible, otherwise, the satellite time service is not credible.

Exemplarily, Δ t is set to 2; in the equipment initialization process, four continuous system periods closest to the current credibility judgment operation time point are obtained; the second receiving time timelnnew and the third receiving time timecctnew of the four periods are respectively:

second receiving time timelnew of first system period₁100, the third receiving time timecctnew of the first system period₁＝101；|timeInNew₁–timeCTCNew₁1, | time in New₁–timeCTCNew₁|<Δt；

Second receiving time timelnew of second system period₂105, the third receiving time timecctnew of the first system period₁＝104；|timeInNew₂–timeCTCNew₂1, | time in New₂–timeCTCNew₂|<Δt；

Second receiving time timelnew of third system period₃109, the third reception time timecctnew of the third system period₃＝110.5；|timeInNew₃–timeCTCNew₃1.5, | timelnew₃–timeCTCNew₃|<Δt；

Second receiving time timelnew of fourth system period₄115, the third receive time timecctnew of the third system period₄＝115.3；|timeInNew₄–timeCTCNew₄0.3, | timelnew₃–timeCTCNew₃|<Δt。

As can be seen from the above, in four consecutive system cycles, | time InNew₁–timeCTCNew₁|、|timeInNew₂–timeCTCNew₂|、|timeInNew₃–timeCTCNew₃I and | timelnNew₄–timeCTCNew₄All is less than delta t, so the satellite time service is credible in the equipment initialization process.

For another example, Δ t is set to 1.5; in the equipment initialization process, three continuous system periods closest to the current credibility judgment operation time point are obtained; the second receiving time timelnnew and the third receiving time timecctnew of the three periods are respectively:

second receiving time timelnew of first system period₁100, third of the first system cycleReceive time timeCTCNew₁＝101；|timeInNew₁–timeCTCNew₁1, | time in New₁–timeCTCNew₁|<Δt；

Second receiving time timelnew of second system period₂105, the third receiving time timecctnew of the first system period₁＝103；|timeInNew₂–timeCTCNew₂2, | time in New₂–timeCTCNew₂|>Δt；

Second receiving time timelnew of third system period₃109, the third reception time timecctnew of the third system period₃＝110；|timeInNew₃–timeCTCNew₃1, | time in New₃–timeCTCNew₃|<Δt。

From the above, in three consecutive system cycles, | timelnnew₂–timeCTCNew₂|>At, therefore, the satellite time service is not trusted during the device initialization process.

And judging whether the current satellite time service is credible or not by the judging method but not limited to the judging method.

If the current satellite time service is credible, giving a time value of a second receiving time timeInNew to a second output time timeOutNew, namely the equipment is successfully initialized, and the time output by the ground control equipment in the current period is a non-all-zero value;

if the current satellite time service is not credible, the equipment initialization fails, and the time output by the ground control equipment in the current period is all zero.

And after the initialization of the equipment fails, restarting the equipment and carrying out initialization operation again.

Step two: and after the communication equipment is initialized successfully, the communication equipment is switched to a real-time running state.

And when the ground control equipment is initialized successfully, the ground control equipment and the ground satellite time service receiving equipment establish normal data communication. The ground control device outputs the newly received satellite time, and the ground control device jumps to a real-time running state at the moment.

For example, as shown in fig. 4, the process flow of the ground control device in the real-time operation state is as follows:

in a real-time operation state, the second receiving time timelnNew received by the ground control equipment is a non-zero time value;

and judging whether the time value of the first output time timeOutOld is all zero values.

If the time value of the first output time timeOutOld is all zero, the time value of the second receiving time timelnew is given to the second output time timeOutNew. Specifically, when the ground control device just shifts to the real-time operating state, the time value of the first output time timeOutOld is all zero.

If the time value of the first output time timeOutOld is not all zero, it is determined whether the second receiving time timelnnew is later than the first output time timeOutOld.

If the second receiving time timelnnew is later than the first output time timeOutOld, which indicates that the second receiving time timelnnew is normal, the time value of the second receiving time timelnnew is given to the second output time timeOutNew.

If the second receiving time timeInNew is not later than the first output time timeOutOld, the first receiving time timeInNew is judged to be abnormal preliminarily, and at the moment, the credibility of the satellite time service is judged. Specifically, the determining step is to determine whether the second receiving time timelnnew is abnormal.

The method for judging the credibility of the satellite time service is the same as the method for judging whether the satellite time service is credible in the first step, and details are not repeated here.

And if the satellite time service is credible, giving the time value of the second receiving time timeInNew to a second output time timeOutNew. Even if the second receiving time timelnnew is not later than the first output time timeOutOld, the time value of the second receiving time timelnnew is given to the second output time timeOutNew, namely the satellite output time of the ground control device.

If the satellite time service is not credible, the internal periodic clock of the ground control equipment is required to be used for time keeping processing. Specifically, the time keeping process includes: and adding a time value obtained by subtracting the first cycle time timeCleOld from the second cycle time timeCleNew and a time value obtained by adding the first output time timeOutOld to the second output time timeOutNew, namely the ground control equipment outputs the timekeeping time based on the cycle clock.

Step three: when the communication equipment can not obtain accurate satellite time, the communication equipment is switched to a timekeeping operation state.

When the communication between the ground control equipment and the ground satellite time service receiving equipment is interrupted or the satellite time sent by the ground satellite time service receiving equipment is all zero value data, the ground control equipment jumps from a real-time running state to a time-keeping running state.

When the ground control equipment is in the punctual operation state, the periodic clock is continuously used for continuing the output time of the ground control equipment. If the ground control equipment receives the satellite time sent by the ground satellite time service receiving equipment again, whether the satellite time is abnormal and/or credible needs to be judged, and the ground control equipment can reuse the satellite time after the satellite time is judged to be normal or credible.

Illustratively, as shown in fig. 5, the processing flow of the ground control apparatus in the time-keeping operation state is as follows:

and under the time-keeping running state, the ground control equipment receives a second receiving time timeInNew and judges whether the time value of the second receiving time timeInNew is not all zero.

When the time value of the second receiving time timelnnew is all zero, it indicates that the satellite time sent by the ground satellite time service receiving equipment is abnormal, and at this time, the internal periodic clock of the ground control equipment needs to be used for time keeping processing. Specifically, the time keeping process includes: and a system cycle time difference obtained by subtracting the first cycle time timeclamped old from the second cycle time timeclamped new is added with a time value obtained by adding the first output time timeOutold, and the second output time timeOutNew is given, namely the ground control equipment outputs the timekeeping time based on the cycle clock.

And when the time value of the second receiving time timeInNew is not all zero, judging whether the second receiving time timeInNew is abnormal or not. Specifically, it is determined whether the second receiving time timelnnew is later than the first output time timeOutOld.

If the second receiving time timelnnew is later than the first output time timeOutOld, which indicates that the second receiving time timelnnew is normal, the time value of the second receiving time timelnnew is given to the second output time timeOutNew, that is, the ground control device outputs the satellite time.

If the second receiving time timeInNew is not later than the first output time timeOutOld, the first receiving time timeInNew is judged to be abnormal preliminarily, and at the moment, the credibility of the satellite time service is judged.

The method for judging the credibility of the satellite time service is the same as the method for judging whether the satellite time service is credible in the first step, and details are not repeated here.

And if the satellite time service is credible, giving the time value of the second receiving time timeInNew to a second output time timeOutNew. Even if the second receiving time timelnnew is earlier than the first output time timeOutOld, the time value of the second receiving time timelnnew is given to the second output time timeOutNew, namely the satellite output time of the ground control device.

If the satellite time service is not credible, the time keeping process is required to be carried out by utilizing the periodic clock. Specifically, the time keeping process includes: and adding a system cycle time difference obtained by subtracting the first cycle time timeclamped old from the second cycle time timeclamped new to a time value obtained by adding the first output time timeOutOld to give a second output time timeOutNew, namely the ground control equipment outputs timekeeping time based on the cycle clock.

Step four: when the communication device obtains accurate satellite time, the communication device switches to a real-time operation state.

When the ground control equipment is communicated with the ground satellite time service receiving equipment to reestablish signal connection and the satellite time sent by the ground satellite time service receiving equipment is valid data, the ground control equipment is switched to a real-time running state.

TABLE 1 System abnormal scene analysis Table

As shown in table 1, the ground control device side adopts different processing modes in different abnormal situations.

When the ground control equipment, the satellite receiver and the ground satellite time service receiving equipment are in normal working states, the satellite receiver and the ground satellite time service receiving equipment are connected and used for sending satellite time to the ground satellite time service receiving equipment; the ground control equipment is connected with the ground satellite time service receiving equipment, and the ground satellite time service receiving equipment sends satellite time to the ground control equipment.

When the ground control equipment is in a starting or restarting state and the satellite receiver and the ground satellite time service receiving equipment are in a normal working state, the ground control equipment does not output communication data. When the ground control equipment is successfully established in signal connection with the ground satellite time service receiving equipment, the ground control equipment enters a real-time running state after being successfully initialized, and communication data containing satellite time can be normally sent.

When the ground satellite time service receiving equipment is in a restarting or abnormal state, and the ground control equipment and the satellite receiver are in a normal working state, the communication between the ground control equipment and the ground satellite time service receiving equipment is interrupted, and the ground control equipment enters a time-keeping running state. When the ground control equipment and the ground satellite time service receiving equipment reestablish signal connection, the ground control equipment enters a real-time running state.

When the satellite receiver is in a starting-up state, a restarting state or an abnormal state, and the ground control equipment and the ground satellite time service receiving equipment are in a normal working state, the ground control equipment receives all-zero value or wrong satellite time from the ground satellite time service receiving equipment, and the ground control equipment enters a time-keeping running state.

The application range of the time keeping method is not limited to the communication equipment in the train operation control system, and the time keeping method is also applicable to other communication equipment.

In order to realize the time keeping method, the invention also provides a time keeping system based on satellite time service, and the time keeping system comprises:

a satellite time acquisition unit for acquiring and transmitting satellite time;

the CTC system clock is used for transmitting the CTC system time;

the periodic clock is used for generating system periodic time, and calculating and sending a system periodic time difference according to the system periodic time;

the first judgment unit is used for acquiring satellite time and CTC system time and judging the credibility of the satellite time;

the second judgment unit is used for acquiring satellite time and judging whether the satellite time is abnormal or not;

the real-time operation unit is used for acquiring and outputting satellite time;

and the time keeping operation unit is used for acquiring the system period time difference, and calculating and outputting the time keeping time according to the system period time difference.

Specifically, the system is started, the satellite time acquisition unit acquires satellite time sent by a time service satellite, and sends the satellite time to the first judgment unit; the CTC system clock sends the CTC system time to a first judgment unit;

the first judging unit receives and judges whether the satellite time is credible or not according to the satellite time and the CTC system time;

if the satellite time is credible, the system is initialized successfully, at the moment, the first judgment unit sends the satellite time to a real-time operation unit, and the real-time operation unit acquires and outputs the satellite time;

if the satellite time is not credible, the system initialization fails, and at the moment, the first judgment unit controls the system to restart to acquire new satellite time again for credibility judgment until the acquired satellite time is credible.

Further, after the system is initialized successfully, the satellite time acquisition unit continues to acquire new satellite time;

the second judging unit acquires the new satellite time and judges whether the new satellite time is abnormal or not;

if the new satellite time is normal, sending the new satellite time to a real-time operation unit, and acquiring and outputting the new satellite time by the real-time operation unit;

if the new satellite time is abnormal, the new satellite time is sent to a first judgment unit for credibility judgment;

the first judging unit acquires the new satellite time, acquires new CTC system time sent by a CTC system clock, and judges the credibility of the new satellite time according to the new satellite time and the new CTC system time;

if the new satellite time is credible, sending the new satellite time to a real-time operation unit, and acquiring and outputting the new satellite time by the real-time operation unit;

and if the new satellite time is not credible, controlling the timekeeping operation unit to acquire a system period time difference, and calculating and outputting the timekeeping time according to the system period time difference.

Exemplarily, the time of a cycle output on the system is set as a first output time timeOutOld, and is initialized to all zero values;

and setting the time output by the system in the period as a second output time timeOutNew, and initializing to be an all-zero value.

The satellite time received from the ground satellite time service receiving equipment in the last period of the system is set as a first receiving time timeInOld, and the first receiving time is initialized to be a full zero value.

And setting the satellite time received by the system from the ground satellite time service receiving equipment in the period as a second receiving time timeInNew.

And setting the time of receiving the CTC clock in the current period of the system as a third receiving time timeCTNew.

Setting the cycle time of a cycle on a cycle clock in the system as a first cycle time timeCycleOld;

the period time of the period clock in the system is set as a second period time timecycle new.

The satellite time acquisition unit establishes signal connection with the ground satellite time service receiving equipment and receives a second receiving time timeInNew sent by the ground satellite time service receiving equipment;

a first judging unit acquires the second receiving time timeInNew and judges the credibility of the second receiving time timeInNew;

if the satellite time is credible, sending the second receiving time timelnNew to a real-time operation unit, endowing a time value of the second receiving time timelnNew to a second output time timeOutNew by the real-time operation unit, and outputting the second output time timeOutNew by the real-time operation unit, namely outputting the satellite time by a system;

and if the second receiving time timeInNew is not credible, switching to a satellite time acquisition unit, and acquiring the satellite time again to judge the credibility until the acquired satellite time is credible.

And after the real-time operation unit outputs a second output time timeOutNew, converting the second output time timeOutNew into a first output time timeOutOld.

The satellite time acquisition unit continues to acquire a new second receiving time timelnew; a second judging unit acquires and judges whether the second receiving time timelnNew is abnormal or not;

if the second receiving time timelnnew is normal, sending the second receiving time timelnnew to a real-time operation unit, endowing the time value of the second receiving time timelnnew to a second output time timeOutNew by the real-time operation unit, and outputting the second output time timeOutNew by the real-time operation unit, namely outputting satellite time by a system;

if the second receiving time timelnnew is abnormal, sending the second receiving time timelnnew to a first judging unit, and judging the credibility of the second receiving time timelnnew by the first judging unit;

if the second receiving time timelnnew is credible, sending the second receiving time timelnnew to a real-time operation unit, endowing the time value of the second receiving time timelnnew to a second output time timeOutNew by the real-time operation unit, and outputting the second output time timeOutNew by the real-time operation unit, namely outputting satellite time by a system;

if the second receiving time timeeinnew is not trusted, the first output time timeOutOld is sent to the time keeping operation unit, the time keeping operation unit obtains the first output time timeOutOld, meanwhile, the time keeping operation unit obtains the first cycle time timecycle old and the second cycle time timecycle new from the cycle clock, and calculates the time keeping time (the first output time timeOutOld + (the second cycle time timecycle new-the first cycle time timecycle old)), the time keeping operation unit gives the time keeping time to the second output time timeOutNew, and the time keeping operation unit outputs the second output time timeOutNew, namely the system outputs the time keeping time.

The satellite time acquisition unit continues to acquire a new second receiving time timelnnew and repeats the judging process, and if the new second receiving time timelnnew cannot be acquired or the acquired new second receiving time timelnnew is abnormal and unreliable, the timekeeping operation unit continues to output the timekeeping time; if the obtained new second receiving time timelnNew is normal or credible, the real-time operation unit outputs the satellite time.

After the system is initialized successfully, whether the system is in a real-time operation state or a punctuality operation state, when the system acquires new satellite time, validity judgment needs to be carried out on the new satellite time. If the new satellite time is effective, the system enters a real-time running state and outputs the new satellite time; if the system is invalid, the system enters a time-keeping running state and outputs time-keeping time.

The periodic clock and the time keeping operation unit are used for providing time keeping time for the system, and the time service satellite and the real-time operation unit are matched to provide reliable and effective time for the system, so that timeliness of the system in the communication process is guaranteed.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.