CN106415299B

CN106415299B - System and method for high reliability monitoring of aircraft

Info

Publication number: CN106415299B
Application number: CN201480078673.7A
Authority: CN
Inventors: ***; Y.丁; L.王; D.颜
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2014-03-07
Filing date: 2014-03-07
Publication date: 2020-12-25
Anticipated expiration: 2034-03-07
Also published as: CN106415299A; WO2015131384A1

Abstract

Systems and methods for high reliability monitoring of an aircraft are provided. In one embodiment, an aircraft surveillance system 100 includes: an aircraft 110 including at least one on-board GNSS receiver 112 that processes a plurality of navigation signals 125 from a plurality of GNSS satellites 120, and further including at least one air-ground communications data link 40, 132, 134 where the GNSS receiver 112 computes current position reports, each of which includes a current position of the aircraft 110 as determined by the at least one on-board GNSS receiver 112 from the plurality of navigation signals 125; and wherein the at least one GNSS receiver 112 transmits the current position report using the at least one air-to-ground communication data link 140, 132, 134 and the raw GNSS measurement information including samples from the plurality of navigation signals 125 is transmitted together as a series of message units 310-1 to 310-6 to the ground station 115.

Description

System and method for high reliability monitoring of aircraft

Background

In addition to Primary Service Radar (PSR) and Secondary Service Radar (SSR) systems, aircraft autonomous position reporting is becoming increasingly important to air traffic service providers for traffic monitoring purposes. Broadcast automatic dependent surveillance (ADS-B) is a technology that is now widely used to enhance awareness of air traffic controllers of aircraft activity, especially in remote areas where PSR and SSR radar coverage is not available.

Airborne autonomous position reporting systems designed for general-purpose aircraft are sometimes integrated with low cost components such as low-end Global Navigation Satellite System (GNSS) chips, satellite communication (SATCOM) chips, and relatively limited central processing units. Using position reports generated by such aircraft, end users are notified of the presence of such aircraft via aircraft symbols on their surveillance displays of the Aircraft Operation Center (AOC) and Air Traffic Control (ATC). However, the integrity and accuracy information of these aircraft may not always be available or provide a sufficient level of confidence to serve air traffic monitoring or flight tracking purposes.

For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for improved systems and methods for high reliability monitoring of aircraft.

Disclosure of Invention

Embodiments of the present invention provide methods and systems for high reliability monitoring of aircraft, and will be understood by reading and studying the following specification.

Systems and methods for high reliability monitoring of an aircraft are provided. In one embodiment, an aircraft surveillance system includes: an aircraft including at least one on-board GNSS receiver that processes a plurality of navigation signals from a plurality of GNSS satellites, and the aircraft further including at least one air-ground communication data link over which the GNSS receiver computes current position reports, each of which includes a current position of the aircraft determined by the at least one on-board GNSS receiver from the plurality of navigation signals; and wherein the at least one GNSS receiver transmits the current position report and raw GNSS measurement information including samples from the plurality of navigation signals as a series of message units together to the ground station using the at least one air-to-ground communications data link.

Drawings

Embodiments of the present invention may be more readily understood, and further advantages and uses thereof more readily apparent, when considered in view of the description of the preferred embodiments and the following figures, in which:

FIG. 1 is a diagram illustrating a monitoring system of one embodiment of the present disclosure;

FIG. 2 is a diagram illustrating a message unit of one embodiment of the present disclosure;

FIG. 3 is a diagram illustrating communication of a current position report and raw GNSS measurement information loop of one embodiment of the present disclosure; and

fig. 4 is a flow chart illustrating a method of one embodiment of the present disclosure.

In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize features relevant to the present invention. Reference characters denote like elements throughout the figures and text.

Detailed Description

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.

Embodiments of the present disclosure provide systems and methods for providing air traffic monitoring and control personnel with accurate position information for aircraft, such as general purpose aircraft that are not equipped with high performance position sensors or Receiver Autonomous Integrity Monitoring (RAIM) enabled onboard systems. With embodiments of the present disclosure, the aircraft continues to broadcast position reports for ground end users using its own low-end on-board GNSS sensors, but augments this data by also transmitting raw GNSS measurements. The ground system hosts sufficient computational power and includes knowledge of GNSS satellite positioning error models that can be used to apply a wide variety of advanced methods on raw GNSS measurements to better positioning solutions and/or estimated position data integrity. As described herein, conventional airborne RAIM functionality may be transferred and integrated with existing ground systems for the purpose of better air traffic monitoring and flight tracking as compared to that available from low cost airborne components. In some embodiments, the ground station may apply one or more corrections typically performed by SBAS/GBAS stations to provide a better location solution. Finally, the present disclosure presents embodiments that utilize existing air-to-ground communications in order to minimize the additional cost associated with launching raw GNSS measurements from an aircraft to a ground station.

FIG. 1 is a diagram illustrating an aircraft surveillance system 100 according to one embodiment of the present disclosure. The monitoring system 100 includes an aircraft 110 that receives navigational signals 125 from a plurality of GNSS satellites 120. The aircraft 110 is also in communication with at least one ground station 115 responsible for collecting and reporting surveillance data for airborne aircraft within a geographic area. For example, the ground station 115 may include an airport or regional aircraft operations center or an air traffic control center. Aircraft 110 includes one or more GNSS receivers 112 that process navigation signals 125 of GNSS satellites 120 and compute a real-time navigation solution indicative of a current location of aircraft 110 and transmit a location report of the current location to ground station 115.

As discussed above, for general purpose aerial vehicles that are not equipped with high performance position sensors or Receiver Autonomous Integrity Monitoring (RAIM) enabled on-board systems, the current position data generated by on-board GNSS receiver 112 may not have sufficient integrity or accuracy to enable controllers at ground station 115 to trust air traffic monitoring or flight tracking purposes. To provide the ground station 115 with the required enhanced integrity and accuracy, the aircraft 110 also transmits GNSS raw satellite measurements received by the on-board GNSS receiver 112 to the ground station 115 using embodiments of the present disclosure. GNSS raw measurements sampled by the GNSS receiver 112 may include, but are not limited to: the number and identification of satellites observed by the on-board GNSS receiver, the number and identification of satellites used by the receiver for positioning, the timestamp associated with each sample of GNSS satellite signals, the pseudorange (or time shift) of each of the observed satellites, and optionally the carrier phase sampled for each of the GNSS satellites observed by the on-board GNSS receiver 112.

As also shown in FIG. 1, the ground station 115 includes a processing system 150 coupled to one or more monitoring workstations 160, each of the one or more monitoring workstations 160 having a display unit 164 that provides a visual indication of aircraft position, airspeed, and other relevant data about the aircraft within the airspace monitored by the ground station 115. The processing system 150 is coupled to either or both of the SATCOM receiver 136 and the terrestrial radio receiver 142. In one embodiment, the aircraft 110 transmits real-time current position updates and GNSS raw satellite measurements via air-to-ground transmissions 140 received by a terrestrial radio receiver 142. In another embodiment, the aircraft 110 transmits real-time current position updates and GNSS raw satellite measurements to the communication satellites 130 via SATCOM transmissions 132, which are then retransmitted to the ground station 115 via satellite transmissions 134 received by a SATCOM receiver 136. In operation, the aircraft 110 may select the use of the air-to-ground transmission 140 or (vers) the use of the communications satellite 130 based on cost, operational capabilities of the ground station 115, or other factors. For example, as the aircraft 110 travels from one air traffic control area to another, it may switch between using air-to-ground transmission and satellite transmission.

In one embodiment, the air-to-ground transmission 140 includes 1090MHz or 978MHz ADS-B broadcasts. For example, the existing ADS-B position report message subtype code represents HPL or HFOM/VFOM and some subtypes carry aircraft operational status information, which may be an indication of its integrity and accuracy when onboard GNSS is RAIM capable. However, when onboard GNSS system 112 does not provide RAIM or provides limited RAIM due to cost limitations, the location data will not be associated with a quality indication or qualified for ADS-B out of specification. Potentially, new optional subtypes may be created for GNSS raw measurements to enable low cost aircraft to obtain the benefits of ADS-B.

In another embodiment, the communication satellites 130 include satellites operating as part of an iridium (iridium) or international maritime communication satellite (Inmarsat) communication satellite network. A wide variety of products and services provide a data link between the aircraft and the ground via satellites. For example, the EMS sky connection provides an end-to-end system consisting of an airborne iridium satellite transceiver LRU, an antenna, an iridium satellite network, a terrestrial iridium satellite gateway, and an end-user application. Transceivers have been built into GPS receivers and location data is transmitted and relayed to the sky connection server. The end user can monitor and record the aircraft flight path for asset tracking. Those location messages are transmitted in a manufacturer-defined format without or with limited accuracy and integrity information, and thus may not meet the performance requirements for ATC monitoring purposes. In this case, raw GNSS measurement samples may be appended to the location message, and the ground will look to location corrections and RAIM to provide a location quality indication. For systems implementing ACARS over iridium, raw GPS measurements may optionally be appended to a user-defined ADS-C slot.

In the embodiment shown in fig. 1, the processing system 150 includes a processor 161, a memory 162, and one or more GNSS satellite positioning error models 163, which error models 163, when executed by the processor 161, implement a GNSS data post-processing algorithm. In one embodiment, ground-based post-processing of GNSS raw measurements may be accomplished at the processing station 150. In other embodiments, wherever sufficient computing power and/or necessary satellite state and signal correction information is available, some or all of the post-processing functions of the processing system 150 may be hosted by an off-site service provider or distributed among the ground station 115 end-user computers (such as, for example, the monitoring workstation 160), or a combination thereof.

The processing system 150 is configured with one or more GNSS reception capabilities (shown at 165) for ephemeris, almanac information or other necessary data or/and remains corresponding to a GNSS operation agent 166 (such as, for example, a GBAS station, SBAS station, etc.), which GNSS operation agent 166 may be implemented by executing a GNSS satellite positioning error model 163. There are many GNSS data post-processing methods that may be applied to the current position and raw GNSS measurements transmitted by the aircraft 110 to the ground station 115 and the processing system 150. For example, in one embodiment, the GNSS satellite positioning error model 163 handles errors such as atmospheric errors, satellite ephemeris errors, and satellite clock drift. In one embodiment, the available error models extract the current majority of error components from any available error model that may be obtained (e.g., from the nearest GBAS airport, SBAS ground facility, or other agent where wide-area GNSS demonstrative data is available)) and apply the model on each of the reported raw pseudorange measurements to obtain a correct position solution for aircraft 110 and positioning accuracy data. In other implementations, the GNSS satellite positioning error model 163 may correct GNSS satellite signal multipath and/or signal false lock errors using different combinations of raw and/or corrected pseudorange data for the position solution, compare each of the results, and identify and isolate bad satellite signals and thus identify potentially falsely reported aircraft positions. With respect to GNSS satellite outages, an authoritative publication (e.g., GPS notification to pilot (NOTAM)) may be used in some embodiments to identify when a known degraded GNSS satellite is used by the aircraft 110 to generate the current location report. That is, raw GNSS measurements transmitted by the aircraft 110 to the ground station 115 will include the number and identity of satellites observed by the on-board GNSS receiver and the number and identity of satellites that the receiver uses for positioning. The processing system 150 may associate such GNSS satellite outage reports with satellite identification information obtained from raw GNSS measurements to mark the current position report as suspect and locally compute a corrected position of the aircraft 110 by omitting GNSS measurements from known degraded satellites. Furthermore, this problem would not need to wait until a complete cycle of raw GNSS measurement packets has been received. As discussed below, the GNSS satellites used by the on-board GNSS receiver 112 are indicated in the header of the first report packet of the raw GNSS measurement transmission cycle so that the inclusion of degraded satellites will be identified immediately at the beginning of the cycle.

The main contributions to GNSS positioning accuracy errors are in fact relatively stable over short periods of time and include phenomena such as, but not limited to, ephemeris error, ionospheric delay, tropospheric delay, and satellite clock drift. Thus, the positioning accuracy data does not necessarily need to be updated for each position report received from the aircraft 110. For example, raw GPS measurements associated with a particular location report may be transmitted uniformly through a series of subsequent location report updates. Once a complete cycle of raw GNSS measurement packets is received and made available to the end-user monitoring workstation 160, the processing system 150 will determine the quality associated with that particular location report until it is updated again after the cycle of raw GNSS measurement packets is received.

Utilizing some avionics communications data links can be expensive, except that it is merely not necessary to provide raw GPS measurements to the ground station 115 at the same rate as position reports. To this end, it may be prudent to optimize the utilization of the data link. For example, satellite data link applications may be sensitive to the size of the data due to cost concerns. The sky-connect system charges the user, for example, for each Message Unit (MU) transmitted via an iridium satellite Short Burst Data (SBD) service. As illustrated by the example message unit 200 in fig. 2, a current location report may be transmitted using a predefined 256-bit (32-byte) data segment communicated over an iridium satellite network (shown at 210). The multiple location reporting feature of the iridium SBD service may pack at least 5 location report packets (shown at 205-1 to 205-5) into a single MU 200 for higher historical resolution. However, only real-time location data is beneficial for monitoring purposes. Thus, locations (shown at 220) of the MU 200 that are equivalent in data size to at least 4 location reports will not be used. With embodiments of the present disclosure, those alternate locations (205-2 through 205-5) may be fully utilized to transmit raw GNSS measurement data.

Referring next to fig. 3, the raw GNSS measurements may be packed in a bit-oriented approach within the same MU that delivers the current position report to the ground station 115. For example, fig. 3 illustrates 6 consecutive MUs 310-1 through 310-6, each including a regular current location report header including an MU identification number and a current location report. Thus, the ground station 115 is refreshed with an updated current location report whenever a new MU is received. The raw GNSS measurements are then communicated to the ground station 115 through a loop of raw GNSS measurement packets transmitted in additional unused portions of each of the MUs 310-1 through 310-6. The first raw GNSS measurement packet in the raw GNSS measurement packet cycle (i.e., shown in MU 310-1) includes a raw GNSS measurement packet header that includes a pre-established code or "symbol" indicating that packet 310-1 is the first packet in the cycle. The raw GNSS measurement packet header also includes a high accuracy timestamp, the number and identification of GNSS satellites observed by GNSS receiver 112 (which in this example is 9 satellites with the respective identification of each satellite illustrated by "a, b, c, d, e, f, g, h, i"), and similarly the number and identification of GNSS satellites used by GNSS receiver 112 (which in this example is 5 satellites with the respective identification of each satellite illustrated by "b, d, f, g, i") to derive the current position report located in the regular current position report header of MU 310-1. In this manner, the raw GNSS measurement packet header within the MU 310-1 informs the processing system 115 that the raw GNSS measurement information provided in the following MUs 310-2 through 310-5 is associated with the current location report transmitted in the MU 310-1. Each of the subsequent MUs 310-2 through 310-5 carries raw pseudorange measurement samples for up to two of the GNSS satellites identified in the raw GNSS measurement packet header. Once the loop is completed, a new loop is started. As should be appreciated, the total number of MUs comprising a packet cycle will vary depending on the number of satellites observed by the on-board GNSS receiver 112. In this manner, raw GNSS measurement information is appended to the regular position report, resulting in additional costs of no service, as no additional MU is required to provide raw GNSS measurement information.

In one embodiment, each MU illustrated in fig. 3 is transmitted at 12 second intervals such that the ground station 115 receives the current location update every 12 seconds. For a raw GNSS measurement packet cycle that includes 6 MUs, a complete set of raw GNSS pseudorange measurement samples is received once per minute for the set of observed GNSS satellites. Because the phenomena that result in GNSS measurement errors are relatively stable over a time period much greater than 1 minute, the processing system 115 may generate and apply location corrections and determine, with sufficiently high confidence, accuracy and integrity information for each of the current location reports provided by the MUs 310-1 through 310-6 for air traffic monitoring purposes. Furthermore, the time stamp and pseudorange information included in the raw GNSS measurement packet does not have a full length. That is, because we have preliminary knowledge of the location of the aircraft 110 from the reported baseline location, the packets following the baseline packet may use an offset or distance from the known time stamp that may significantly reduce the required bits, resulting in as short a delay in accuracy and integrity processing as possible.

For example, in one embodiment, the SATCOM communications server (which may be integrated within the processing system 150 or other ground station 115 device) decodes the location of the aircraft 110 from the transmitted obtained (pull) SBD data via the satellite 130 from the location reports after the existing procedure, and makes the currently reported location for the aircraft 110 provided by each MU 310-1 through 310-6 immediately available to the monitoring workstation 160 upon receipt. Additionally, the processing system 150 refreshes the GNSS raw measurement buffer for this traffic starting from the first MU (i.e., 310-1) of the GNSS measurement packet cycle until the end of the GNSS measurement packet cycle (i.e., MU 310-5 for the example illustrated in fig. 3). Upon receipt of the final MU of the GNSS measurement grouping cycle, collection of the necessary data for the processing system 150 is completed to complete the error calculation and quality determination associated with the reported position on the first MU 310-1 of the cycle. Along with the GNSS satellite positioning error model 163 and any additional satellite error data that may be provided by the contract agent, the reported position 3D error for each position report is also calculated and the level of accuracy and integrity is determined. The position corrections may be applied to the latitude, longitude, and altitude data of the aircraft 110, directly to the position report provided by the last MU of the raw GNSS measurement packet cycle, and later cycles until the new corrections are updated. The reported position, corrected position, along with associated quality data are sent to a contract ATC system interface (such as monitoring workstation 160) to enable monitoring of aircraft 110. Although the description of fig. 2 and 3 focuses primarily on iridium message units, the term "message unit" and the various other embodiments illustrated by these figures are so limited and may be applied to other message protocol structures in which packets may be structured and used to convey both position reports and raw GNSS measurements in the manner shown in fig. 3.

FIG. 4 is a flow chart illustrating a method of aircraft surveillance of one embodiment of the present invention. The method begins at 410 with an on-board GNSS receiver receiving a plurality of Global Navigation Satellite System (GNSS) signals at an aircraft. The method continues to 420 where a transmission including a position report is sent to the ground station, the position report including a current position of the aircraft as determined by the on-board GNSS receiver, and the method continues to 430 where a transmission including raw GNSS measurements based on the samples of the plurality of GNSS signals is sent to the ground station. As discussed above with respect to fig. 2 and 3, the transmission of the position reports and raw GNSS measurements at 420 and 430 may be implemented simultaneously through the transmission of a message unit (such as, but not limited to, an iridium message unit) configured to deliver both the position reports and the raw GNSS measurements. In one embodiment, a complete current position report is transmitted via each message unit while distributing the transmission of raw GNSS measurements over a cycle that includes multiple message units. GNSS raw measurement information may include, but is not limited to: the number and identification of satellites observed by the on-board GNSS receiver, the number and identification of satellites used by the receiver for positioning, a timestamp associated with each sample of GNSS satellite signals, a pseudorange (or time shift) of each of the observed satellites, and optionally a carrier phase (phrase) for each of the GNSS satellites observed by the on-board GNSS receiver. Also, in alternative embodiments, the transmission of GNSS raw measurement information and the current position report may be implemented by over-the-air to terrestrial communications transmissions or satellite communications transmissions.

The processes shown at 410, 420, and 430 illustrate one method embodiment to be implemented on an aircraft. In one embodiment, the method may continue at 440 at the ground station, where the current position report and the GNSS raw measurement information are received. The ground station may then proceed to 450 where the position of the aircraft from the current position report is decoded and provided to the monitoring workstation. It should be appreciated that the methods as shown at 450 and 460 may occur simultaneously. The ground station also proceeds at 460 with applying one or more GNSS satellite positioning error models to the GNSS raw measurement information to calculate an error calculation and a quality determination, wherein the error calculation and quality determination are associated with at least a first current position report of the current position reports. Accordingly, the method continues to 470 where a corrected aircraft position is determined based on the error calculation and the quality determination. The reported position 3D error for each position report is also calculated and applied to the aircraft position information displayed at the monitoring workstation, along with the GNSS satellite positioning error model and any additional satellite error data that may be provided. One or both of accuracy and integrity levels may also be displayed.

In one example of an embodiment, in operation, an aircraft equipped with a low cost integrated satellite data link location reporting device (which has voice call capability) is traveling through a radar-free coverage area and about to transit through an off-limits area via a 20km wide aisle designated for civilian aviation operation. This aircraft, which normally does not have a GNSS sensor that meets the specification of Technical Standards (TSO) C129A, is not eligible for this transfer. However, this traffic is signed with a terminal-based demo function activated on the radar terminal, and the controller at the regional control center continues to monitor. Finally, this traffic elicits advisories about the monitoring terminals of the controllers because of continuous airspace violations and/or degradation of the integrity of the reported position of the aircraft. The controller takes this traffic information and selects a position correction option that utilizes raw GNSS measurements received from an aircraft such as described in any of the above embodiments. Based on post-processing of the raw GNSS measurements at the ground station, the corrected position for the aircraft is mapped back to the transit route. The controller now takes more attention to monitoring this traffic and initiating satellite voice calls to the aircraft in addition to the regular air traffic workload. The aircraft pilot can confirm his location via landmarks or Visual Flight Rules (VFR) checkpoints after receiving the call and reset the on-board tracking components of the aircraft. The indication on the supervisor's monitoring terminal returns to normal after the aircraft location is reacquired. After completing the raw GNSS measurement packet cycle (about 1 minute) indicating that the aircraft actually avoided the restricted area, then accuracy and integrity indices and position corrections are available, avoiding the need for further investigation and possible interception of the aircraft.

Example embodiments.

Example 1 includes a method for aircraft surveillance, the method comprising: receiving, by an onboard GNSS receiver, a plurality of Global Navigation Satellite System (GNSS) signals at an aircraft; sending a transmission to a ground station including current position reports, each position report including a current position of the aircraft as determined by an on-board GNSS receiver; a transmission is sent to a ground station that includes raw GNSS measurement information based on samples of a plurality of GNSS signals received at an aircraft.

Example 2 includes the method of example 1, wherein at the ground station the method further comprises: receiving a current position report and a GNSS original measurement result information flow; decoding the position of the aircraft from the current position report and providing the position of the aircraft to a monitoring workstation; applying one or more GNSS satellite positioning error models to the GNSS raw measurement information to calculate an error calculation and a quality determination, wherein the error calculation and the quality determination are associated with at least a first current position report of the current position reports; and determining a corrected aircraft position based on the error calculation and the quality determination.

Example 3 includes the method of example 2, further comprising: displaying a symbol representing the aircraft on the monitoring workstation based on the corrected aircraft position.

Example 4 includes the method of any of examples 1-3, wherein the current position report and the raw GNSS measurement information are transmitted together by a plurality of packets within a data link communication flow structured to convey both the current position report and the raw GNSS measurement information.

Example 5 includes the method of example 4, further comprising transmitting the plurality of packets to the ground station over a satellite communications data link.

Example 6 includes the method of any one of examples 4-5, further comprising transmitting the plurality of packets to a ground station over a broadcast automatic dependent surveillance (ADS-B) communication link.

Example 7 includes the method of any one of examples 4-6, wherein the plurality of packets includes a series of message units, wherein a first message unit includes a first header including a first current position report, and wherein a first loop of GNSS raw measurement information associated with the first current position report is allocated over a plurality of the series of message units.

Example 8 includes the method of example 7, wherein the series of message units includes iridium message units.

Example 9 includes the method of any one of examples 7-9, wherein the first message unit further includes a second header associated with the GNSS raw measurement information, the second header including a timestamp associated with the first position report, a number and identification of GNSS satellites observed by the on-board GNSS receiver, and a number and identification of GNSS satellites used by the on-board GNSS receiver to derive the first current position report.

Example 10 includes the method of example 9, wherein a first iteration of GNSS raw measurement information includes raw pseudorange measurement samples captured by an onboard GNSS receiver from each of a plurality of GNSS signals observed by the onboard GNSS receiver.

Example 11 includes an aircraft monitoring system, comprising: an aircraft including at least one on-board Global Navigation Satellite System (GNSS) receiver that processes a plurality of navigation signals from a plurality of GNSS satellites, and further including at least one air-ground communications data link where the at least one GNSS receiver calculates current position reports, each of which includes a current position of the aircraft determined by the at least one on-board GNSS receiver from the plurality of navigation signals; and wherein the at least one GNSS receiver transmits the current position report and raw GNSS measurement information comprising samples from the plurality of navigation signals as a series of message units together to the ground station by using the at least one air-to-ground communication data link.

Example 12 includes the system of any of examples 10, wherein the first message unit comprises a first header comprising a first current position report, and wherein a first cycle of raw GNSS measurement information associated with the first current position report is allocated over a plurality of the series of message units.

Example 13 includes an aircraft monitoring system, comprising: a processing system located in the air traffic monitoring ground station; one or more monitoring workstations coupled to the processing system, wherein at least one monitoring workstation includes a display unit that provides a visual indication of aircraft position information; and at least one air-ground communication receiver coupled to the processing system and further communicatively coupled to a Global Navigation Satellite System (GNSS) receiver on the aircraft; wherein the processing system receives a current position report from a GNSS receiver on the aircraft and causes the at least one monitoring workstation to generate a visual indication of aircraft position information based on the current position report; wherein the processing system further receives raw GNSS measurement information from a GNSS receiver on-board the aircraft, the raw GNSS measurement information comprising samples of raw pseudorange measurements captured by the GNSS receiver from navigation signals transmitted by a plurality of GNSS satellites observed by the GNSS receiver; wherein the processing system applies the one or more GNSS satellite positioning error models to the raw GNSS measurement information to calculate correction data and corrects the visual indication of the aircraft position information at the first monitoring workstation based on the correction data.

Example 14 includes the system of example 13, wherein the current position report and the raw GNSS measurement information are received by the at least one air-to-ground communication receiver as a series of message units; wherein the first message element comprises a first header comprising a first current position report, and wherein a first cycle of raw GNSS measurement information associated with the first current position report is allocated across a plurality of the series of message elements.

Example 15 includes the system of any one of examples 14, wherein the first message unit further includes a second header associated with the GNSS raw measurement information, the second header including a timestamp associated with the first location report, a number and identification of GNSS satellites observed by the on-board GNSS receiver, and a number and identification of GNSS satellites used by the on-board GNSS receiver to derive the first current location report.

Example 16 includes the system of any of examples 14-15, wherein the first loop of raw GNSS measurement information comprises raw pseudorange measurement samples captured by a GNSS receiver from each of a plurality of GNSS satellites observed by the GNSS receiver.

Example 17 includes the system of any one of examples 13-16, wherein the at least one air-ground communication receiver is communicatively coupled to a GNSS receiver on the aircraft via a satellite communication data link.

Example 18 includes the system of any one of examples 13-17, wherein the at least one air-ground communication receiver is communicatively coupled to a GNSS receiver on board the aircraft via a broadcast automatic dependent surveillance (ADS-B) communication link.

Example 19 includes the system of any one of examples 13-18, wherein the one or more GNSS satellite positioning error models correct the current position report for at least one of atmospheric errors, satellite ephemeris errors, and satellite clock drift.

Example 20 includes the system of any of examples 13-19, wherein the processing system is to apply the one or more GNSS satellite positioning error models to the raw GNSS measurement information through a function hosted by an off-board service provider away from the ground station.

In various alternative embodiments, any of the systems or methods described throughout this disclosure may be implemented on one or more airborne avionics or ground-based computer systems including a processor executing code implementing processes, models, modules, functions, managers, software layers and interfaces, and other elements described with respect to fig. 1-4, stored on an airborne non-transitory data storage device. Accordingly, other embodiments of the present disclosure include program instructions residing on computer readable media, which when implemented by such an onboard avionics computer system, enable them to implement the embodiments described herein. As used herein, the term "computer-readable medium" refers to a tangible memory storage device having a non-transitory physical form. Such non-transitory physical forms may include computer memory devices such as, but not limited to, punch cards, magnetic disks or tape, any optical data storage system, flash read-only memory (ROM), non-volatile ROM, Programmable ROM (PROM), erasable programmable ROM (E-PROM), Random Access Memory (RAM), or any other form of temporary memory storage system or device that is permanent, semi-permanent, or has a physically tangible form. The program instructions include, but are not limited to, computer-executable instructions executed by a computer system processor and a hardware description language such as Very High Speed Integrated Circuit (VHSIC) hardware description language (VHDL).

Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art appreciate that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.

Claims

1. A method for aircraft (110) surveillance, the method comprising:

receiving, by an on-board GNSS receiver (112), a plurality of Global Navigation Satellite System (GNSS) signals at an aircraft (110);

sending transmissions (140), (134) to a ground station (115) including current location reports, each including a current location of the aircraft (110) as determined by an on-board GNSS receiver (112); and

sending to a ground station (115) a transmission (140), (134) comprising raw GNSS measurement information based on samples of a plurality of GNSS signals received at an aircraft (110), the raw GNSS measurement information comprising samples of raw pseudorange measurements captured by a GNSS receiver (112) from navigation signals emitted by a plurality of GNSS satellites (120) as observed by the GNSS receiver (112);

wherein the method further comprises, at the ground station:

receiving a current position report and a GNSS original measurement result information flow;

decoding the position of the aircraft (110) from the current position report and providing the position of the aircraft (110) to a monitoring workstation (160); and

applying one or more GNSS satellite positioning error models (163) to the GNSS raw measurement information to compute an error calculation and a quality determination, wherein the error calculation and quality determination are associated with at least a first current position report (310-1) of the current position reports;

determining a corrected aircraft position based on the error calculation and the quality determination; and

displaying a symbol representing the aircraft (110) on the monitoring workstation (160) based on the corrected aircraft position,

wherein the current position report and the raw GNSS measurement information are transmitted together by a plurality of packets (310-1) to (310-6) within a data link communication flow configured to convey both the current position report and the raw GNSS measurement information.

2. The method of claim 1, wherein the plurality of packets comprises a series of message units (310-1) through (310-6), wherein a first message unit (310-1) comprises a first header including a first current position report, and wherein a first cycle of GNSS raw measurement information associated with the first current position report is allocated across a plurality of the series of message units (310-1) through (310-6).

3. An aircraft (110) surveillance system, the system comprising:

a processing system (150) located in the air traffic monitoring ground station;

one or more monitoring workstations (160) coupled to the processing system (150), wherein at least one monitoring workstation (160) includes a display unit (164) that provides a visual indication of aircraft position information; and

at least one air-ground communication receiver (142), (136) coupled to the processing system (150) and also communicatively coupled to a Global Navigation Satellite System (GNSS) receiver (112) onboard the aircraft (110);

wherein the processing system (150) receives the current location report from the GNSS receiver (112) onboard the aircraft (110) and causes the at least one monitoring workstation (160) to generate a visual indication of aircraft location information based on the current location report;

wherein the processing system (150) further receives raw GNSS measurement information from a GNSS receiver (112) onboard the aircraft (110), the raw GNSS measurement information comprising samples of raw pseudorange measurements captured by the GNSS receiver (112) from navigation signals transmitted by a plurality of GNSS satellites (120) as observed by the GNSS receiver (112);

wherein the processing system (150) applies the one or more GNSS satellite positioning error models (163) to the raw GNSS measurement information to calculate correction data and corrects the visual indication of the aircraft position information at the first monitoring workstation (160) based on the correction data;

wherein the current position report and the raw GNSS measurement information are received as a series of message units by at least one air-to-ground communication receiver (142), (136);

wherein the first message unit (310-1) comprises a first header comprising a first current position report, and wherein a first cycle of raw GNSS measurement information associated with the first current position report is distributed over a plurality of the series of message units (310-1) through (310-6);

wherein the first message unit (310-1) further comprises a second header associated with GNSS raw measurement information, the second header comprising a timestamp associated with the first position report, a number and identification of GNSS satellites (120) observed by the on-board GNSS receiver (112), and a number and identification of GNSS satellites (120) used by the on-board GNSS receiver (112) to derive a first current position report;

wherein a first cycle of raw GNSS measurement information comprises raw pseudorange measurement samples captured by a GNSS receiver (112) from each of a plurality of GNSS satellites (120) observed by the GNSS receiver (112).