Method and device for improving time accuracy of satellite-borne ADS-B message

Abstract

The invention discloses a method and a device for improving time accuracy of a satellite-borne ADS-B message. The method comprises the following steps: simulating a satellite integrated electronic subsystem to broadcast a time code message and a second pulse signal through ground measurement equipment; when the falling edge of the pulse per second is detected, zero clearing is carried out at the same time through an accumulation counter and a millisecond counter, and cyclic accumulation counting is started; a broadcasted time code message is received, the received time code message is stored in a register, and the time code message is in an uncorrected state; comparing a currently received time message millisecond value with a millisecond count value output by software timing, and eliminating an error introduced by time code message bus broadcast delay; according to the ADS-B message tracking and monitoring method, the ADS-B message header moment is calculated, the corrected whole second value of the register and the current millisecond counter value are spliced and written into the calculated ADS-B message data, the time precision of the ADS-B message is improved to 0.1 millisecond from second, and more accurate tracking and monitoring of a flying target are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of ADS-B payloads, and in particular to a method and a device for improving the time accuracy of satellite-borne ADS-B messages. Background Art

[0002] ADS-B is the abbreviation of Automatic Dependent Surveillance-Broadcast. ADS-B uses the information generated by navigation equipment and other airborne equipment as data sources, and uses ground-to-air / air-to-air data links as communication means. It automatically broadcasts the position, speed and other data used for monitoring to achieve real-time ground-to-air and air-to-air monitoring; at the same time, it receives broadcast information from other flying aircraft to monitor and command each aircraft in the airspace. It provides a safer and more efficient air traffic monitoring technology for air traffic control systems and airlines, which can effectively improve the control of controllers and pilots over the operating situation, further expand the monitoring coverage in the region, and significantly improve the safety operation efficiency and safe flight of flights in the region.

[0003] The satellite-borne ADS-B payload can calculate information including aircraft position, identity, flight altitude, speed, etc. based on the received ADS-B signal. However, the satellite-borne ADS-B time code depends on the satellite bus broadcast. The broadcast cycle of the satellite time code is generally 1 full second. The satellite-borne ADS-B payload usually writes the received bus broadcast time directly into the message. Therefore, there is a situation where the time information of the ADS-B message calculated between two broadcast time codes is the same. Due to the lack of time information within seconds, the time accuracy of the ADS-B message is low, which affects the high-precision continuous monitoring and tracking of the aircraft trajectory. Summary of the invention

[0004] The purpose of the present invention is to provide a method and device for improving the time accuracy of satellite-borne ADS-B messages, so as to overcome the problem of insufficient time code accuracy of ADS-B messages received by current satellite-borne ADS-B payloads.

[0005] The present invention provides a method for improving the time accuracy of satellite-borne ADS-B messages, comprising: Simulate the satellite integrated electronic subsystem broadcasting time code messages and pulse-per-second signals through ground measurement equipment; When the falling edge of the second pulse is detected, the accumulative counter and the millisecond counter are simultaneously cleared and the cyclic accumulative counting begins; receiving a broadcast time code message and storing the received time code message in a register, wherein the time code message is in an uncorrected state; Compare the millisecond value of the currently received time message with the millisecond count value output by the software timing, correct the current register time code message according to the comparison result and update the time code register message to complete the correction of the whole second value of the time code transmitted by the bus, thereby eliminating the error introduced by the bus broadcast delay of the time code message; Calculate the ADS-B message header time, concatenate the corrected register's whole second value with the current millisecond counter value, and write them into the calculated ADS-B message data.

[0006] Preferably, comparing the millisecond value of the currently received time message with the millisecond count value output by the software timing, and correcting the current register time code message and updating the time code register message according to the comparison result comprises: Determine whether the millisecond count value of the broadcast time code is greater than the millisecond count value of the software timing; If the millisecond count value of the broadcasted time code is less than the millisecond count value output by the software timing, the whole second value of the received time code is stored, and the whole second value of the current register time code message is accurate; If the broadcast time code millisecond count value is greater than the millisecond count value output by the software timing, the received time code whole second value + 1 is stored, and the current register time code message is in a corrected state.

[0007] The present invention provides a device for improving the time accuracy of satellite-borne ADS-B messages, which implements the method for improving the time accuracy of satellite-borne ADS-B messages as described in an embodiment of the present invention. The device includes a software timing management module, a bus timing module, a satellite-borne GPS second pulse timing module and a time code assignment management module; The software timing management module includes an accumulative counter and a millisecond counter, which is used to simultaneously clear the accumulative counter and the millisecond counter and start cyclic accumulative counting when a falling edge of a second pulse is detected; The bus time calibration module is used to receive the broadcast time code message and store the received time code message into a register, wherein the time code message is in an uncalibrated state; The onboard GPS second pulse timing module is used to correct the whole second value of the time code transmitted by the bus, compare the millisecond value of the currently received time message with the millisecond count value output by the software timing, correct the current register time code message according to the comparison result, and update the time code register message to complete the correction of the whole second value of the time code transmitted by the bus, thereby eliminating the error introduced by the bus broadcast delay of the time code message; The time code assignment management module is used to calculate the ADS-B message header time, splice the corrected register whole second value with the current millisecond counter value, and write them into the calculated ADS-B message data.

[0008] Preferably, the time code message received by the bus timing module is the satellite-borne GPS broadcast time, and the time code format includes millisecond information.

[0009] Preferably, the range of the cumulative counter is configured according to the clock frequency used to achieve 0.1 millisecond steps of the millisecond counter.

[0010] Preferably, the satellite-borne GPS second pulse timing module includes a comparator for comparing the millisecond counter value with the time code millisecond value and correcting the whole second value.

[0011] Preferably, in the time code assignment management module, the ADS-B message header is solved as the time node, the whole second information and the millisecond counter value are spliced ​​and written into the currently solved ADS-B message data, so that the message time code is accurate to 0.1 millisecond.

[0012] The present invention also provides a satellite-borne ADS-B message monitoring device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the satellite-borne ADS-B message monitoring method as described in the embodiment of the present invention are implemented.

[0013] The present invention also provides a computer-readable medium storing a computer program, wherein the computer program is executed by a processor to implement the steps in the method for monitoring satellite-borne ADS-B messages as described in an embodiment of the present invention.

[0014] The beneficial effects of the present invention compared with the prior art are: The present invention provides a method and device for improving the time accuracy of satellite-borne ADS-B messages, which are applied in the satellite-borne ADS-B payload message processing algorithm. The satellite-borne second pulse time calibration module eliminates the error introduced by the broadcast delay of the time code message bus through comparison and correction, thereby ensuring the accuracy of the whole second value of the time code message. The software counter uses a high-steady-state temperature compensated crystal oscillator in the hardware to ensure the frequency stability, thereby ensuring the accuracy of the millisecond counter. The time of the resolved ADS-B message header is used as the time node, and the corrected whole second value and the millisecond counter value are spliced ​​and written into the resolved ADS-B message information, thereby improving the time code accuracy of the ADS-B message. The method is very necessary for the ADS-B message resolution, and has important significance for the continuous tracking and monitoring of aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flow chart of a method for improving the time accuracy of satellite-borne ADS-B messages in an embodiment of the present invention; Figure 2It is a schematic diagram of broadcast time code and pulse-per-second timing in one embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Embodiment 1 The present invention provides a method for improving the time accuracy of satellite-borne ADS-B messages, including a detailed process and the relationship between the various components, such as Figure 1 As shown, the specific steps include: Create software timing management module, bus timing module, satellite-borne GPS second pulse timing module, and time code assignment management module inside FPGA; The ground measuring equipment simulates the satellite integrated electronic subsystem broadcasting time code message and second pulse signal, wherein the ground measuring equipment simulates the satellite integrated electronic subsystem broadcasting time code message and second pulse signal, see Figure 2 As shown, the broadcast cycle is 1 second; When the falling edge of the second pulse is detected, the cumulative counter and the millisecond counter are simultaneously cleared and a cyclic cumulative counting is started; it can be understood that when the software timing management module detects the falling edge of the second pulse signal en_pulse, the cumulative counter count and the millisecond counter sec_count are simultaneously cleared and a cyclic cumulative counting is started, the step of the cumulative counter is 1, and the counting range is 0~10000. For example, the crystal oscillator frequency used in this embodiment is 100MHz, and the millisecond counter is increased by one every time the count reaches 10000. The range of the millisecond counter is 0~10000, and the millisecond counter is cleared every time the count reaches 10000, that is, 1000 milliseconds; Receive a broadcast time code message, and store the received time code message into a register, wherein the time code message is in an uncorrected state. In this embodiment, when it is detected that the time code message enable signal en_utc_time is valid, the received time code message is stored into the register, and the current time code is uncorrected and includes a broadcast delay; When the time code register message in the bus timing module is updated, the satellite-borne GPS second pulse timing module compares the millisecond value of the received time message with the millisecond count value of the software timing, that is, compares the millisecond value of the currently received time message with the millisecond count value output by the software timing, and corrects the current register time code message according to the comparison result and updates the time code register message to complete the correction of the whole second value of the time code transmitted by the bus, thereby eliminating the error introduced by the bus broadcast delay of the time code message; Calculate the ADS-B message header time, concatenate the corrected register's whole second value with the current millisecond counter value, and write them into the calculated ADS-B message data.

[0018] In this embodiment, comparing the millisecond value of the currently received time message with the millisecond count value output by the software timing, correcting the current register time code message according to the comparison result and updating the time code register message includes: Determine whether the millisecond count value of the broadcast time code is greater than the millisecond count value of the software timing; If the millisecond count value of the broadcasted time code is less than the millisecond count value output by the software timing, the whole second value of the received time code is stored, and the whole second value of the current register time code message is accurate; If the broadcast time code millisecond count value is greater than the millisecond count value output by the software timing, the received time code whole second value + 1 is stored, and the current register time code message is in a corrected state.

[0019] Those skilled in the art will understand that if the millisecond count value of the time code of the received satellite-borne integrated electronic broadcast is less than the millisecond count value of the software timing management module, then the whole second value of the current register time code message is accurate and can be used directly; if the millisecond count value of the time code of the received satellite-borne integrated electronic broadcast is greater than the millisecond count value of the software timing management module, it means that the millisecond counter has counted to 10,000 and has been cleared once, the current whole second value should be increased by one and stored in the register, and the time code message is corrected.

[0020] Based on the same inventive concept, the present invention also provides a device for improving the time accuracy of satellite-borne ADS-B messages, realizing the above-mentioned method for improving the time accuracy of satellite-borne ADS-B messages, the device includes a software timing management module, a bus timing module, a satellite-borne GPS second pulse timing module and a time code assignment management module; The software timing management module includes an accumulative counter and a millisecond counter, which is used to simultaneously clear the accumulative counter and the millisecond counter and start cyclic accumulative counting when a falling edge of a second pulse is detected; The bus time calibration module is used to receive the broadcast time code message and store the received time code message into a register, wherein the time code message is in an uncalibrated state; The onboard GPS second pulse timing module is used to correct the whole second value of the time code transmitted by the bus, compare the millisecond value of the currently received time message with the millisecond count value output by the software timing, correct the current register time code message according to the comparison result, and update the time code register message to complete the correction of the whole second value of the time code transmitted by the bus, thereby eliminating the error introduced by the bus broadcast delay of the time code message; The time code assignment management module is used to solve the ADS-B message header moment, splice the corrected register whole second value with the current millisecond counter value, and write them into the solved ADS-B message data. It can be understood that when the module detects that the ADS-B message header update signal en_message solved by the header solving module is valid, the module splices the register whole second with the current millisecond counter value, writes them into the ADS-B message information at this moment, and outputs them externally.

[0021] Specifically, the time code message received by the bus timing module is the satellite-borne GPS broadcast time, and the time code format includes millisecond information.

[0022] Specifically, the range of the cumulative counter is configured according to the clock frequency used to achieve 0.1 millisecond steps of the millisecond counter.

[0023] Specifically, the satellite-borne GPS second pulse timing module includes a comparator for comparing the millisecond counter value with the time code millisecond value and correcting the whole second value.

[0024] Specifically, in the time code assignment management module, the ADS-B message header is solved as the time node, the whole second information and the millisecond counter value are spliced ​​and written into the currently solved ADS-B message data, so that the message time code is accurate to 0.1 milliseconds.

[0025] The present invention also provides a satellite-borne ADS-B message monitoring device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the satellite-borne ADS-B message monitoring method as described in the embodiment of the present invention are implemented.

[0026] The format of the ADS-B message provided in this implementation contains the precise time code as follows: The comparison table of ADS-B message effects before and after implementation is as follows: A method for improving the time code accuracy of satellite-borne ADS-B messages provided by an embodiment of the present invention is applied in a satellite-borne ADS-B payload message processing algorithm. The satellite-borne second pulse timing module eliminates the error introduced by the broadcast delay of the time code message bus through comparison and correction, thereby ensuring the accuracy of the whole second value of the time code message. The software counter uses a high-steady-state temperature compensated crystal oscillator in the hardware to ensure frequency stability, thereby ensuring the accuracy of the millisecond counter. The resolved ADS-B message header moment is used as a time node, and the corrected whole second value and the millisecond counter value are spliced ​​and written into the resolved ADS-B message information, thereby improving the time code accuracy of the ADS-B message. The method is very necessary for ADS-B message resolution, and is of great significance to the continuous tracking and monitoring of aircraft.

[0027] The present invention also provides a computer-readable medium storing a computer program, characterized in that the computer program is executed by a processor to implement the steps in the method for monitoring satellite-borne ADS-B messages as described in an embodiment of the present invention.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the time accuracy of satellite-borne ADS-B messages, characterized in that: include: Simulate the satellite integrated electronic subsystem broadcasting time code messages and pulse-per-second signals through ground measurement equipment; When the falling edge of the second pulse is detected, the accumulative counter and the millisecond counter are simultaneously cleared and the cyclic accumulative counting begins; receiving a broadcast time code message and storing the received time code message in a register, wherein the time code message is in an uncorrected state; Compare the millisecond value of the currently received time message with the millisecond count value output by the software timing, correct the current register time code message according to the comparison result and update the time code register message to complete the correction of the whole second value of the time code transmitted by the bus, thereby eliminating the error introduced by the bus broadcast delay of the time code message; Calculate the ADS-B message header time, concatenate the corrected register's whole second value with the current millisecond counter value, and write them into the calculated ADS-B message data.

2. The method for improving the time accuracy of satellite-borne ADS-B messages according to claim 1, characterized in that: The step of comparing the millisecond value of the currently received time message with the millisecond count value output by the software timing, and correcting the current register time code message and updating the time code register message according to the comparison result comprises: Determine whether the millisecond count value of the broadcast time code is greater than the millisecond count value of the software timing; If the millisecond count value of the broadcasted time code is less than the millisecond count value output by the software timing, the whole second value of the received time code is stored, and the whole second value of the current register time code message is accurate; If the broadcast time code millisecond count value is greater than the millisecond count value output by the software timing, the received time code whole second value + 1 is stored, and the current register time code message is in a corrected state.

3. A device for improving the time accuracy of satellite-borne ADS-B messages, characterized in that: A method for improving the time accuracy of satellite-borne ADS-B messages as claimed in any one of claims 1 to 2 is implemented, wherein the device comprises a software timing management module, a bus timing module, a satellite-borne GPS second pulse timing module and a time code assignment management module; The software timing management module includes an accumulative counter and a millisecond counter, which is used to simultaneously clear the accumulative counter and the millisecond counter and start cyclic accumulative counting when a falling edge of a second pulse is detected; The bus time calibration module is used to receive the broadcast time code message and store the received time code message into a register, wherein the time code message is in an uncalibrated state; The onboard GPS second pulse timing module is used to correct the whole second value of the time code transmitted by the bus, compare the millisecond value of the currently received time message with the millisecond count value output by the software timing, correct the current register time code message according to the comparison result, and update the time code register message to complete the correction of the whole second value of the time code transmitted by the bus, thereby eliminating the error introduced by the bus broadcast delay of the time code message; The time code assignment management module is used to calculate the ADS-B message header time, splice the corrected register whole second value with the current millisecond counter value, and write them into the calculated ADS-B message data.

4. The device for improving the time accuracy of satellite-borne ADS-B messages according to claim 3, characterized in that: The time code message received by the bus timing module is the satellite-borne GPS broadcast time, and the time code format includes millisecond information.

5. The device for improving the time accuracy of satellite-borne ADS-B messages according to claim 3, characterized in that: The range of the up-counter is configured according to the clock frequency used to achieve 0.1 millisecond steps of the millisecond counter.

6. The device for improving the time accuracy of satellite-borne ADS-B messages according to claim 3, characterized in that: The satellite-borne GPS second pulse timing module includes a comparator for comparing the millisecond counter value with the time code millisecond value and correcting the whole second value.

7. The device for improving the time accuracy of satellite-borne ADS-B messages according to claim 3, characterized in that: In the time code assignment management module, the ADS-B message header is solved as the time node, the whole second information and the millisecond counter value are spliced ​​and written into the currently solved ADS-B message data, so that the message time code is accurate to 0.1 millisecond.

8. A satellite-borne ADS-B message monitoring device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps in the method for monitoring satellite-borne ADS-B messages as claimed in any one of claims 1 to 2 are implemented.

9. A computer-readable medium storing a computer program, characterized in that: The computer program is executed by a processor to implement the steps in the method for monitoring satellite-borne ADS-B messages as claimed in any one of claims 1 to 2.

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