CN113636090B - Method, system, and medium for monitoring a real-time clock of an aircraft - Google Patents
Method, system, and medium for monitoring a real-time clock of an aircraft Download PDFInfo
- Publication number
- CN113636090B CN113636090B CN202110973329.6A CN202110973329A CN113636090B CN 113636090 B CN113636090 B CN 113636090B CN 202110973329 A CN202110973329 A CN 202110973329A CN 113636090 B CN113636090 B CN 113636090B
- Authority
- CN
- China
- Prior art keywords
- time
- real
- time clock
- aircraft
- clock
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENTS OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64D43/00—Arrangements or adaptations of instruments
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64F—GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
- B64F5/00—Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for
- B64F5/60—Testing or inspecting aircraft components or systems
Abstract
The invention discloses a method for monitoring a real-time clock of an aircraft, characterized in that the method comprises: obtaining a current reference time; obtaining a real-time clock time of the aircraft; determining a time difference between the current reference time and the real-time clock time; and comparing the time difference to a monitoring threshold and determining that the real time clock of the aircraft is misaligned if the time difference is greater than the monitoring threshold. Corresponding systems and computer-readable storage media are also disclosed. The invention can automatically monitor the real-time clock of the aircraft.
Description
Technical Field
The present invention relates to clock sources for aircraft, and more particularly, to methods, systems, and media for monitoring a real-time clock for an aircraft.
Background
For aircraft (e.g., aircraft such as civilian aircraft), it is important to determine the exact time. The time of the aircraft is typically provided by the Flight Management System (FMS) of the aircraft. For example, the current time of the aircraft may typically be displayed in an auxiliary information (AUX) interface of an indication recording system of the aircraft. Typically, flight management systems for aircraft utilize a reference time as the accurate time. The reference time may be, for example, from a coordinated Universal Time (UTC) of a Global Navigation Satellite System (GNSS) source, or the like. However, the reference time is not always available for various reasons (failure to receive GNSS signals, failure of related components, etc.). When reference time is not available, flight management systems typically use the Real Time Clock (RTC) local to the aircraft as a time source. Therefore, it is also important to maintain the accuracy of the real time clock. However, for various reasons, the real-time clock may experience time drift, resulting in time misalignment of the real-time clock.
Therefore, a solution is needed that can automatically monitor the real time clock of an aircraft.
Disclosure of Invention
The present invention has been made to solve the above-mentioned problems of the prior art. The present invention solves the above-described problems by comparing the time reading of the real-time clock of the aircraft to a reference time and comparing the difference between the two to a threshold difference to determine if the real-time clock is misaligned.
In one aspect, a method for monitoring a real-time clock of an aircraft is disclosed, the method comprising: obtaining a current reference time; obtaining a real-time clock time of the aircraft; determining a time difference between the current reference time and the real-time clock time; and comparing the time difference to a monitoring threshold and determining that the real time clock of the aircraft is misaligned if the time difference is greater than the monitoring threshold.
Preferably, the method is performed periodically with a predetermined periodicity.
Preferably, the predetermined period is 1 second.
Preferably, the reference time is from coordinated universal time.
Preferably, the current reference time is obtained from a reference time determination module, the real-time clock time is obtained from a real-time clock time determination module, wherein the monitoring threshold is determined based on: drift threshold t caused by line delay and jitter of acquiring the real time clock 1 (ii) a Normal drift tolerance t of a reference time clock oscillator associated with the reference time determination module 2 (ii) a And a normal drift tolerance t of a real time clock oscillator associated with said real time clock time determination module 3 。
Preferably, the normal drift tolerance of the reference time clock oscillator is at least partially dependent on aging and temperature of the reference time clock oscillator, and the normal drift tolerance of the real time clock oscillator is at least partially dependent on aging and temperature of the real time clock oscillator.
Preferably, the monitoring threshold is further based on a time resolution of a real time clock of the aircraft.
Preferably, after determining that the real-time clock of the aircraft is misaligned, an alert message is issued to one or more other systems of the aircraft.
Preferably, an automatic calibration operation is performed on the real time clock of the aircraft upon determining that the real time clock of the aircraft is misaligned.
In another aspect, a system for monitoring a real-time clock of an aircraft is disclosed, the system comprising: a reference time determining module for determining a current reference time; a real-time clock time determination module for determining a real-time clock time of the aircraft; and a monitoring module for: receiving a current reference time from the reference time determination module; receiving a real-time clock time from the real-time clock time determination module; determining a time difference between the current reference time and the real-time clock time; and comparing the time difference to a monitoring threshold and determining that the real time clock of the aircraft is misaligned if the time difference is greater than the monitoring threshold.
Preferably, the monitoring module periodically determines whether the real-time clock of the aircraft is misaligned according to a predetermined period.
Preferably, the reference time is from coordinated universal time.
Preferably, the current reference time is obtained from a reference time determination module, the real-time clock time is obtained from a real-time clock time determination module, wherein the monitoring threshold is determined based on: drift threshold t caused by line delay and jitter of acquiring the real time clock 1 ；
Normal drift tolerance t of a reference time clock oscillator associated with the reference time determination module 2 (ii) a And
normal drift of a real time clock oscillator associated with the real time clock time determination moduleDifference t 3 。
Preferably, the normal drift tolerance of the reference time clock oscillator is at least partially dependent on aging and temperature of the reference time clock oscillator, and the normal drift tolerance of the real time clock oscillator is at least partially dependent on aging and temperature of the real time clock oscillator.
Preferably, the monitoring threshold is further based on a time resolution of a real time clock of the aircraft.
Preferably, the aircraft monitoring system further comprises a fault reporting module, and after determining that the real-time clock of the aircraft is misaligned, the monitoring module sends a real-time clock fault message to the fault reporting module, and the fault reporting module sends an alarm message.
In yet another aspect, a non-transitory computer-readable storage medium is disclosed that stores computer-executable instructions that, when executed by a computer, may perform any of the methods described previously.
The scheme provided by one or more embodiments of the invention can realize one or more of the following technical effects: the drift of the real-time clock can be monitored in real time;
the alarm and automatic calibration can be realized when the real-time clock is out of alignment;
high accuracy time can be provided for the flight management system.
Drawings
There is shown in the drawings, which are incorporated herein by reference, non-limiting preferred embodiments of the present invention, the features and advantages of which will be apparent. Wherein:
FIG. 1 illustrates a schematic diagram of a system for monitoring a real-time clock of an aircraft in accordance with an embodiment of the present description.
FIG. 2 illustrates a schematic flow diagram of a method for monitoring a real-time clock of an aircraft in accordance with an embodiment of the present description.
Fig. 3 shows a schematic diagram of a situation where the reference time and the real time clock time drift in the same direction.
Fig. 4 shows a schematic diagram of a situation where the reference time and the real time clock time drift in opposite directions.
Detailed Description
Specific embodiments of the present invention will be described below with reference to the accompanying drawings. It is to be understood that the preferred embodiments of the present invention are shown in the drawings only, and are not to be considered limiting of the scope of the invention. Obvious modifications, variations and equivalents will occur to those skilled in the art based on the embodiments shown in the drawings, and the technical features in the described embodiments may be combined arbitrarily without contradiction, all of which fall within the scope of the present invention.
Referring to fig. 1, a schematic diagram of a system 100 for monitoring a real-time clock of an aircraft in accordance with an embodiment of the present description is shown.
Preferably, the system 100 is applied in an aircraft, preferably an aircraft, in particular a civil aircraft. It will be appreciated that embodiments of the present description may also be applied to other aircraft than airplanes, provided that the aircraft is suitable for implementing aspects of embodiments of the present description. It should also be understood that while the term "aircraft" is used herein, the concepts described herein may also be implemented in a land vehicle, a water vehicle, a space vehicle, or other machine, and such concepts are to be interpreted as falling within the scope of the embodiments of the present disclosure. Further, the system 100 may also be implemented in other use devices besides aircraft.
Preferably, the system 100 may be implemented in an integrated modular avionics system (IMA) of an aircraft to provide time for other systems of the aircraft.
As shown in FIG. 1, the system 100 may include a reference time determination module 102, a real-time clock time determination module 104, and a monitoring module 106. The reference time determination module is used for determining a reference time used by the aircraft. In a preferred example, the reference time determination module 102 may employ UTC (universal time coordinated) from a GNSS (global navigation satellite system) source as the reference time. The global satellite navigation system may include, for example, the Beidou satellite navigation System of China, the GPS system of the United states, the GLONASS system of Russia, and the European Galileo system, among others. In other examples, the reference time determination module 102 may employ other reference times from other sources. Under normal circumstances, the Flight Management System (FMS) of an aircraft uses the reference time as its operating time.
Specifically, the reference time determination module 102 may periodically receive a flight management system time (e.g., piFMSTime shown in fig. 1) from a Flight Management System (FMS) as the current reference time. The flight management system time may be, for example, a reference time (e.g., UTC time) from a GNSS source.
The reference time determination module 102 may also output a local time (such as the poiimatime shown in fig. 1) as the local time of the aircraft. The local time of the aircraft may be referenced by the relevant systems of the aircraft.
When a reference time from a GNSS source is available, the local time output by the reference time determination module 102 (such as the poiimatime shown in fig. 1) may be the reference time. When the reference time from the GNSS source is not available, the local time output by the reference time determination module 102 may be the real-time clock time received from the real-time clock determination module 104.
In addition, in order to determine the current reference time, a reference time clock oscillator (not shown in the figure) is further included in the reference time determination module 102. The clock oscillator is one of the main devices of the system 100, and the clock oscillator is used to generate a clock signal by using the vibration generated by the repeated mechanical deformation of the wafer. The use of a reference time clock oscillator to determine or maintain a reference time is well known to those skilled in the art and will not be described in detail herein.
While the reference time clock oscillator is operating, the reference time clock oscillator may cause some time drift, which may be caused by aging of the reference time clock oscillator and ambient temperature variations, for example. Hereinafter, the time drift brought about by the reference time clock oscillator is referred to as reference time clock oscillator time drift. Under normal conditions, the reference time clock oscillator timeThe drift is within a tolerance, which is referred to hereinafter as the reference time clock oscillator normal drift tolerance (which is denoted as t hereinafter) 2 )。
As shown in fig. 1, the reference time determination module 102 may transmit the obtained reference time to the real time clock time determination module 104 and the monitoring module 106.
In addition, the reference time determination module 102 may also communicate the reference time determination module status to the monitoring module 106. The reference time determination module status may, for example, inform the monitoring module 106 whether a reference time from a GNSS source is available.
The real time clock time determination module 104 may include a real time clock oscillator (not shown) to determine the real time clock time. The details of determining the real-time clock time by the real-time clock oscillator are not described herein. The real-time clock time determination module 104 may communicate the determined real-time clock time to the reference time determination module 102 and the monitoring module 106.
It will be appreciated that, similar to the reference time clock oscillator, the real time clock oscillator may introduce time drift, which may be caused, for example, by aging of the real time clock oscillator and ambient temperature variations. Hereinafter, the time drift caused by the real-time clock oscillator is referred to as the real-time clock oscillator time drift. Under normal conditions, the rtc time drift is within a tolerance, which will be referred to hereinafter as the rtc normal drift tolerance (which will be referred to hereinafter as t) 3 )。
If the reference time from the GNSS source (e.g., UTC time) is determined to be unavailable at the reference time determination module 102, the reference time determination module 102 may output the real-time clock time from the real-time clock time module as the local time of the aircraft.
In addition, the real time clock time determination module 104 may also receive a reference time from the reference time determination module. The real-time clock time determination module 104 may periodically obtain the reference time to synchronize the clock of the real-time clock time, so as to calibrate the clock of the real-time clock time determination module 104 itself if necessary, thereby ensuring that the two modules work in a coordinated and synchronous manner, and realizing clock synchronization.
The monitoring module 106 may obtain the reference time from the reference time determination module 102. The monitoring module 106 may also obtain the real-time clock time from the real-time clock time determination module 104.
The monitoring module 106 may also receive a reference time determination module status from the reference time determination module 102, by which the monitoring module 106 may confirm whether the reference time determination module 102 is operational and determine its health.
Subsequently, the monitoring module 106 may determine a time difference between the reference time (which may also be referred to as a current reference time) and the real-time clock time.
The monitoring module 106 may also compare a time difference between the current reference time and the real-time clock to a monitoring threshold. The manner in which the monitoring threshold is determined is described in more detail below.
If the time difference is not greater than the monitoring threshold, the real-time clock of the aircraft may be deemed not misaligned.
If the time difference is greater than the monitoring threshold, the real-time clock of the aircraft may be deemed misaligned. The monitoring module 106 may output a real-time clock fault signal when the real-time clock of the aircraft is determined to be out of alignment. The real time clock fault signal may be output to the fault reporting module 108, for example.
Preferably, the operations described above may be performed periodically at a predetermined period to continuously monitor whether the real time clock of the aircraft is misaligned. Preferably, the predetermined period may be relatively small. For example, the predetermined period may be 1 second. More preferably, the predetermined period may be 0.5 seconds.
The fault reporting module 108, upon receiving a real-time clock fault signal from the monitoring module 106 of the system 100, may issue an alert message to one or more other systems of the aircraft to inform the one or more other systems of the real-time clock misalignment. The warning message may also inform an operator of the aircraft that the real-time clock is misaligned. The alert information may be, for example, an audio alert (e.g., output an alert sound), a light alert (e.g., cause an associated light to flash a light), or alert information that may be displayed on a display. After receiving the alarm, the operator may perform relevant processing, such as calibrating a real-time clock.
The real time clock fault signal may also be output to the reference time determination module 102. The reference time determination module 102 may determine that the real time clock time as the backup time is unavailable through the received real time clock failure signal, and thus take corresponding action.
Referring to FIG. 2, a schematic flow diagram of a method 200 for monitoring a real-time clock of an aircraft is shown, according to an embodiment of the present description. The method 200 may be performed, for example, by the monitoring module 106 of the system 100 as shown in FIG. 1.
The method 200 comprises the following steps: at operation 202, a current reference time may be obtained. For example, the monitoring module 106 may receive the reference time from the reference time determination module 102 as the current reference time. As described above, the reference time may be from a coordinated universal time.
The method 200 may further include: at operation 204, a real-time clock time for the aircraft may be obtained. For example, the monitoring module 106 may receive the real-time clock time from the real-time clock time determination module 104.
The method 200 may further include: at operation 206, a time difference between the current reference time and the real-time clock time may be determined. For example, the current reference time may be subtracted from the real-time clock time and the absolute value of the result taken as the time difference between the real-time clock time and the current reference time.
The method 200 may further include: at operation 208, the time difference may be compared to a monitoring threshold and, if the time difference is greater than the monitoring threshold, a real-time clock misalignment of the aircraft is determined. The determination of the monitoring threshold will be described in detail below.
Preferably, the above method may be periodically performed at a predetermined period. Preferably, the predetermined period is 1 second. More preferably, the predetermined period is 0.5 seconds. Other suitable predetermined periods may be used.
As described above, a warning message may be issued upon determining that the real-time clock of the aircraft is misaligned. For example, after determining that the real-time clock is misaligned, a real-time clock fault signal may be output by the monitoring module 106 to the fault reporting module 108, with the fault reporting module 108 sending an alert message to one or more other systems of the aircraft. As described above, the fault reporting module 108 may also issue other forms of alarm information.
In a more preferred embodiment, after determining that the real-time clock of the aircraft is misaligned, an auto-calibration operation may be performed on the real-time clock of the aircraft-for example, the real-time clock time determination module 104 may perform an auto-calibration, i.e., replace its own real-time clock time with the reference time from the synchronization reference time determination module 102.
In some examples, the method 200 further comprises: a reference time determination module status (not shown in fig. 2) is obtained. For example, as shown in FIG. 1, the monitoring module 106 may obtain the reference time determination module status from the reference time determination module 102. The reference time determination module status may, for example, indicate whether a reference time is available. If the reference time is not available, the monitoring module 106 may not perform some of the operations described above (e.g., operations 202, 206, and 208, etc.).
Further, the method 200 may further include: upon determining the real time clock misalignment of the aircraft, a real time clock fault signal may be sent to the reference time determination module 102 to inform the reference time determination module 102 of the real time clock misalignment.
The monitoring threshold t is described below max The determination of (1).
It will be appreciated that the normal time difference for the monitoring module 106 may come from the following aspects:
1. normal drift tolerance t associated with the reference time clock oscillator of the reference time determination module 102 2 . As described above, this normal drift tolerance t 2 May depend at least in part on the aging and temperature of the reference time clock oscillator. Normal drift tolerance t associated with reference time clock oscillator 2 An example of (c) is, for example, 390 ms.
2. And real timeNormal drift tolerance t associated with a real time clock oscillator of a clock time determination module 3 . As described above, this normal drift tolerance t 3 May depend at least in part on the age and temperature of the real time clock oscillator. Normal drift tolerance t associated with real time clock oscillator 3 An example of (d) is 460ms, for example.
3. Drift threshold t caused by line delay and jitter of acquiring the real time clock 1 。
It will be appreciated that the monitoring threshold t is set max May depend on the normal time difference. That is, the monitoring threshold may be determined based at least in part on the following factors: drift threshold t caused by line delay and jitter of acquiring the real time clock 1 (ii) a Normal drift tolerance t associated with a reference time clock oscillator of a reference time determination module 2 (ii) a And a normal drift tolerance t associated with a real time clock oscillator of the real time clock time determination module 3 . The monitoring threshold may also be based on a time resolution of a real time clock of the aircraft of the monitoring threshold. Temporal resolution refers to the smallest time interval that can be resolved. The time resolution unit may be 100ms, depending on the design requirements of the real time clock. It is conceivable that the higher the time resolution of the real-time clock, the more stringent the monitoring threshold should be set, i.e. t max The smaller the value of (c). The monitoring threshold may also be based on other factors, such as the error that is tolerated for proper operation of the relevant components of the aircraft.
Under normal circumstances, it should be considered that the normal range of the time difference Δ t between the current reference time and the real-time clock time as determined by the monitoring module 106 is the sum of the three, i.e., t 1 +t 2 +t 3 . Thus, the monitoring threshold may be set to t max Is the sum of the three, i.e. t max ＝t 1 +t 2 +t 3 。
It will be appreciated that the threshold is the time difference between the current reference time and the real time clock time, however there is also drift in the current reference time that is obtained. In order to understand whether the above-mentioned setting of the monitoring threshold can meet the requirements of the actual situation, the time difference between the current reference time and the real-time clock time is further analyzed below. The current reference time may be understood as a standard time determined by the GNSS source.
At the setting of the normal drift monitoring threshold t max The real time clock drift that can be detected depends on whether the reference time and the real time clock time drift in the same or different directions. Referring to fig. 3 and 4, schematic diagrams of the case where the reference time and the real time clock time drift in the same direction and in opposite directions, respectively, are shown.
As shown in fig. 3 and 4, it is assumed that the drift of both is 0 at time 0. As time t increases, the drift of either the current reference time (e.g., obtained by monitoring module 106 from reference time determination module 102) or the real-time clock time (e.g., obtained by monitoring module 106 from real-time clock time determination module 104) increases. It should be appreciated that while the drifts of both are shown as linear increases in fig. 3 and 4, such increases may be non-linear.
Suppose that at some time t, the drift of the reference time is t 2 Time difference Δ t between the current reference time and the real-time clock time, it can be appreciated that the clock drift of the real-time clock time relative to the current reference time (drift at 0, i.e., the horizontal axis in fig. 3 and 4) at this time can be determined as follows:
when the reference time and the real-time clock time drift in the same direction, the sum of the time drift of the reference time and the time difference between the real-time clock time and the reference time, i.e. Δ t + t 2 ；
When the reference time and the real-time clock time drift in opposite directions, the difference (absolute value) obtained by subtracting the time difference between the real-time clock time and the reference time from the time drift of the reference time, i.e. | Δ t-t 2 |。
To allow clock drift of the real time clock time relative to the current reference time to be within the allowable range t, since we may not know whether the current reference time drifts in the same direction or in the opposite direction to the real time clock time tolerance In the above two cases, it is necessary to ensure that the larger of the clock drifts is less than or equal to t tolerance I.e. max { Δ t + t 2 ,|Δt-t 2 |}≤t tolerance 。
To facilitate understanding, we describe below one specific example, assuming the following scenario exists (assuming the following drift is clock drift per hour):
1. normal drift tolerance t associated with the reference time clock oscillator of the reference time determination module 102 2 Is 390 ms;
2. normal drift tolerance t associated with a real time clock oscillator of a real time clock time determination module 3 Is 460 ms;
3. drift threshold t caused by line delay and jitter of acquiring the real time clock 1 In the range of 200ms and 300ms, we take the larger value of 300 ms.
At this point, t may be set to ensure that drift introduced during normal operation does not inadvertently trigger false alarms of real-time clock faults max Minimum set to t max ＝t 1 +t 2 +t 3 300ms +390ms +460ms 1150 ms. The monitoring threshold t may be set in consideration of the resolution of the real time clock time (which is assumed to be about 100ms) max Set to 1200 ms.
We next examine whether the above-described monitoring threshold settings meet the requirements for the components of the flight management system to function properly. As described above, max { Δ t + t should be satisfied 2 ,|Δt-t 2 |}≤t tolerance . When the threshold value of Δ t is set as the monitoring threshold value t max Then max { t } should be guaranteed max +t 2 ,|t max -t 2 |}≤t tolerance 。
For the above example, it should be ensured that {1200ms +390ms, |1200ms-390ms | } ≦ t tolerance . I.e. the threshold value for clock drift of the real time clock time relative to the current reference time is 1590 ms. Thus, the above scheme can be considered satisfactory as long as the clock drift required for the components of the flight management system to function properly is no more than 1590 ms. In other words, the present solution enables a certainty of 1590ms accuracy per hour in flight management systems, which meets the time requirements of current flight management systemsAnd (6) obtaining.
Additionally, an apparatus is disclosed that includes a processor and a memory having stored thereon computer-executable instructions that, when executed by the processor, cause the processor to perform the method of the embodiments described herein.
Additionally, a system comprising means for implementing the methods of the embodiments described herein is also disclosed.
It is to be understood that methods according to one or more embodiments of the present description can be implemented in software, firmware, or a combination thereof.
It should be understood that the embodiments in this specification are described in a progressive manner, and that the same or similar parts in the various embodiments may be referred to one another, with each embodiment being described with emphasis instead of the other embodiments. In particular, as for the apparatus and system embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference may be made to some descriptions of the method embodiments for relevant points. It is to be appreciated that the present specification discloses a number of embodiments, and that the disclosure of such embodiments may be understood by reference to each other.
It should be understood that the above description describes particular embodiments of the present specification. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
It should be understood that an element described herein in the singular or shown in the figures only represents that the element is limited in number to one. Furthermore, modules or elements described or illustrated herein as separate may be combined into a single module or element, and modules or elements described or illustrated herein as single may be split into multiple modules or elements.
It is also to be understood that the terms and expressions employed herein are used as terms of description and not of limitation, and that the embodiment or embodiments of the specification are not limited to those terms and expressions. The use of such terms and expressions is not intended to exclude any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications may be made within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims should be looked to in order to cover all such equivalents.
Also, it should be noted that while the present invention has been described with reference to specific embodiments thereof, it should be understood by those skilled in the art that the above embodiments are merely illustrative of one or more embodiments of the present invention, and that various changes and substitutions of equivalents may be made without departing from the spirit of the invention, and therefore, it is intended that all such changes and modifications to the above embodiments be included within the scope of the appended claims.
It is to be understood that methods according to one or more embodiments of the present description can be implemented in software, firmware, or a combination thereof.
It should be understood that the embodiments in this specification are described in a progressive manner, and that the same or similar parts in the various embodiments may be referred to one another, with each embodiment being described with emphasis instead of the other embodiments. In particular, as for the apparatus and system embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference may be made to some descriptions of the method embodiments for relevant points. It is to be appreciated that the present specification discloses a number of embodiments, and that the disclosure of such embodiments may be understood by reference to each other.
It should be understood that the above description describes particular embodiments of the present specification. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
It should be understood that an element described herein in the singular or shown in the figures only represents that the element is limited in number to one. Furthermore, modules or elements described or illustrated herein as separate may be combined into a single module or element, and modules or elements described or illustrated herein as single may be split into multiple modules or elements.
It is also to be understood that the terms and expressions employed herein are used as terms of description and not of limitation, and that the embodiment or embodiments of the specification are not limited to those terms and expressions. The use of such terms and expressions is not intended to exclude any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications may be made within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims should be looked to in order to cover all such equivalents.
Also, it should be noted that while the present invention has been described with reference to specific embodiments thereof, it should be understood by those skilled in the art that the above embodiments are merely illustrative of one or more embodiments of the present invention, and that various changes and substitutions of equivalents may be made without departing from the spirit of the invention, and therefore, it is intended that all such changes and modifications to the above embodiments be included within the scope of the appended claims.
Claims (15)
1. A method for monitoring a real-time clock of an aircraft, the method comprising:
obtaining a current reference time;
obtaining a real-time clock time of the aircraft;
determining a time difference between the current reference time and the real-time clock time; and
comparing the time difference to a monitoring threshold and determining a real-time clock misalignment of the aircraft if the time difference is greater than the monitoring threshold,
wherein the current reference time is obtained from a reference time determination module, the real-time clock time is obtained from a real-time clock time determination module, wherein the monitoring threshold is determined based on:
a drift threshold t1 caused by line delay and jitter of the real time clock being acquired;
a normal drift tolerance t2 of a reference time clock oscillator associated with the reference time determination module; and
a normal drift tolerance t3 of a real time clock oscillator associated with the real time clock time determination module.
2. The method of claim 1, wherein the method is performed periodically with a predetermined periodicity.
3. The method of claim 2, wherein the predetermined period is 1 second.
4. The method of claim 1, wherein the reference time is from a coordinated universal time.
5. The method of claim 1, wherein the normal drift tolerance of the reference time clock oscillator is at least partially dependent on aging and temperature of the reference time clock oscillator, and the normal drift tolerance of the real time clock oscillator is at least partially dependent on aging and temperature of the real time clock oscillator.
6. The method of claim 1, wherein the monitoring threshold is further based on a time resolution of a real-time clock of the aircraft.
7. The method of claim 1, wherein after determining that the real-time clock of the aircraft is misaligned, issuing a warning message to one or more other systems of the aircraft.
8. The method of claim 1, wherein an auto-calibration operation is performed on the real-time clock of the aircraft after determining the real-time clock of the aircraft is misaligned.
9. A system for monitoring a real-time clock of an aircraft, the system comprising:
a reference time determining module for determining a current reference time;
a real-time clock time determination module for determining a real-time clock time of the aircraft; and
a monitoring module to:
receiving a current reference time from the reference time determination module;
receiving a real-time clock time from the real-time clock time determination module;
determining a time difference between the current reference time and the real-time clock time; and
comparing the time difference to a monitoring threshold and determining a real-time clock misalignment of the aircraft if the time difference is greater than the monitoring threshold,
wherein the monitoring threshold is determined based on:
a drift threshold t1 caused by line delay and jitter of the real time clock being acquired;
a normal drift tolerance t2 of a reference time clock oscillator associated with the reference time determination module; and
a normal drift tolerance t3 of a real time clock oscillator associated with the real time clock time determination module.
10. The system of claim 9, wherein the monitoring module periodically determines whether the real-time clock of the aircraft is misaligned according to a predetermined period.
11. The system of claim 9, wherein the reference time is from a coordinated universal time.
12. The system of claim 9, wherein the normal drift tolerance of the reference time clock oscillator is at least partially dependent on aging and temperature of the reference time clock oscillator, and the normal drift tolerance of the real time clock oscillator is at least partially dependent on aging and temperature of the real time clock oscillator.
13. The system of claim 9, wherein the monitoring threshold is further based on a time resolution of a real-time clock of the aircraft.
14. The system of claim 9, further comprising a fault reporting module, the monitoring module to send a real-time clock fault message to the fault reporting module upon determining that the real-time clock of the aircraft is misaligned, and the fault reporting module to send an alert message to one or more other systems of the aircraft.
15. A non-transitory computer-readable storage medium storing computer-executable instructions that, when executed by a computer, perform the method of any one of claims 1-8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110973329.6A CN113636090B (en) | 2021-08-24 | 2021-08-24 | Method, system, and medium for monitoring a real-time clock of an aircraft |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110973329.6A CN113636090B (en) | 2021-08-24 | 2021-08-24 | Method, system, and medium for monitoring a real-time clock of an aircraft |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113636090A CN113636090A (en) | 2021-11-12 |
| CN113636090B true CN113636090B (en) | 2022-08-09 |
Family
ID=78423542
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110973329.6A Active CN113636090B (en) | 2021-08-24 | 2021-08-24 | Method, system, and medium for monitoring a real-time clock of an aircraft |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113636090B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115361317A (en) * | 2022-07-26 | 2022-11-18 | 西安羚控电子科技有限公司 | Clock monitoring method, clock adjusting method, clock system and storage medium |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1250530A (en) * | 1997-02-25 | 2000-04-12 | 塞克斯丹航空电子公司 | Low cost modular architecture for piloting an aerodyne operating with high level of security |
| US7606541B1 (en) * | 2006-04-12 | 2009-10-20 | Nortel Network Limited | Enhanced holdover for synchronous networks employing packet switched network backhaul |
| CN110471087A (en) * | 2019-08-13 | 2019-11-19 | 北京电子工程总体研究所 | A kind of the time drift calculation method and system of spacecraft |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7253671B2 (en) * | 2004-06-28 | 2007-08-07 | Intelliserv, Inc. | Apparatus and method for compensating for clock drift in downhole drilling components |
| US7738611B2 (en) * | 2006-08-07 | 2010-06-15 | Harris Stratex Networks, Inc. | Remote monitoring and calibration of system reference clock using network timing reference |
| TWI415497B (en) * | 2010-08-27 | 2013-11-11 | Univ Nat Taiwan | Device, system, and method for time synchronization |
| WO2012082274A2 (en) * | 2010-11-19 | 2012-06-21 | Rambus Inc. | Timing-drift calibration |
| AU2013331048A1 (en) * | 2012-10-19 | 2015-04-09 | Schweitzer Engineering Laboratories, Inc. | Time distribution switch |
| US9963242B1 (en) * | 2014-04-29 | 2018-05-08 | Blue Storm Associates, Inc. | Mountable sensor for an aircraft |
| US10336463B2 (en) * | 2017-11-02 | 2019-07-02 | Embraer S.A. | Aircraft stall warning/protection with time-varying maximum angle of attack settings for icing conditions |
-
2021
- 2021-08-24 CN CN202110973329.6A patent/CN113636090B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1250530A (en) * | 1997-02-25 | 2000-04-12 | 塞克斯丹航空电子公司 | Low cost modular architecture for piloting an aerodyne operating with high level of security |
| US7606541B1 (en) * | 2006-04-12 | 2009-10-20 | Nortel Network Limited | Enhanced holdover for synchronous networks employing packet switched network backhaul |
| CN110471087A (en) * | 2019-08-13 | 2019-11-19 | 北京电子工程总体研究所 | A kind of the time drift calculation method and system of spacecraft |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113636090A (en) | 2021-11-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8260552B2 (en) | Systems and methods for determining location information using dual filters | |
| US11187813B2 (en) | Correction information integrity monitoring in navigation satellite system positioning methods, systems, and devices | |
| US6856905B2 (en) | Systems and methods for fault detection and exclusion in navigational systems | |
| US8200430B2 (en) | Method and apparatus for providing integrity information for users of a global navigation system | |
| JP6521635B2 (en) | Multilevel / multithreshold / multipersistent GPS / GNSS atomic clock monitoring | |
| CN109100748B (en) | Navigation integrity monitoring system and method based on low-orbit constellation | |
| KR101477041B1 (en) | Satellite Signal Anomaly Monitoring System for DGNSS Reference Station and Its Monitoring Method | |
| US9581698B2 (en) | Systems and methods to monitor for false alarms from ionosphere gradient monitors | |
| Oehler et al. | The Galileo integrity concept | |
| CN113636090B (en) | Method, system, and medium for monitoring a real-time clock of an aircraft | |
| CN109791421B (en) | Time arbitration circuit | |
| JP2016225779A (en) | Reference signal generating device, electronic equipment, mobile body, data communication device, and digital terrestrial communication network | |
| JP2009288243A (en) | Continuity improvement method in dual-frequency satellite navigation system | |
| CN112835070B (en) | Navigation satellite time-frequency autonomous recovery system | |
| CN113259902B (en) | Synchronization method based on V2X vehicle-mounted terminal, V2X vehicle-mounted terminal and vehicle | |
| US20110169693A1 (en) | Integrity communication in a satellite navigation system | |
| US20200249361A1 (en) | Alternate uncertainty limits in the presence of a detected satellite fault | |
| Rodriguez et al. | Satellite autonomous integrity monitoring (SAIM) for GNSS systems | |
| Lee et al. | Horizontal advanced RAIM performance sensitivity to mischaracterizations in integrity support message values | |
| US11604439B2 (en) | GNSS time synchronization in redundant systems | |
| Weiss et al. | On-board signal integrity for GPS | |
| JP7376542B2 (en) | Measuring device and measuring method | |
| US20210328759A1 (en) | Fault-tolerant time server for a real-time computer sytem | |
| US8072375B2 (en) | Method and apparatus for integrity communication in a navigation satellite system | |
| RU2584091C1 (en) | Method for real-time monitoring of integrity of navigation field of global navigation satellite system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |