CN-121995416-A - NRTK differential data optimization method and system for low-bandwidth link

CN121995416ACN 121995416 ACN121995416 ACN 121995416ACN-121995416-A

Abstract

The invention discloses an NRTK differential data optimization method and system for a low-bandwidth link, wherein the method comprises the following steps of obtaining visible satellite signals and packaging the visible satellite signals into RTCM differential text protocol frames; the method comprises the steps of scoring information quantity of each satellite in an RTCM differential message protocol frame, reserving observation data of Top-k optimal satellites, reorganizing the observation data to form a simplified frame, performing single-point positioning calculation on the simplified frame to obtain a rough positioning result of an edge node, triggering to generate a virtual reference station request, generating a virtual reference station in a range of a rough positioning point adjacent to a short base line, generating differential correction data by the virtual reference station, fusing the differential correction data and the simplified frame, performing extended Kalman filtering, performing a least square ambiguity decorrelation adjustment algorithm, and outputting a final positioning result. The invention effectively solves the problem that the traditional NRTK positioning is dependent on a high-bandwidth link technology in non-edge resolving, and improves the accuracy and stability of a low-cost positioning technology.

Inventors

TANG JIE
Bei Yi
FENG TING
Liang Xinger
ZHANG PEIMING
ZHANG JIAN

Assignees

华南理工大学
广东电网有限责任公司电力调度控制中心

Dates

Publication Date: 20260508
Application Date: 20260225

Claims (10)

1. The NRTK differential data optimization method for the low-bandwidth link is characterized by comprising the following steps of: Obtaining visible satellite signals and packaging the visible satellite signals into RTCM differential message protocol frames; scoring the information quantity of each satellite in the RTCM differential message protocol frame, reserving the observation data of Top-k optimal satellites, and reorganizing the frames to form a simplified frame; Performing single-point positioning calculation on the simplified frame to obtain a rough positioning result of the edge node; triggering and generating a virtual reference station request; generating a virtual reference station in the range of the rough positioning point adjacent to the short base line, and generating differential correction data by the virtual reference station; And fusing the differential correction data and the reduced frames, executing extended Kalman filtering, performing a least square ambiguity decorrelation adjustment algorithm, and outputting a final positioning result.
2. The NRTK differential data optimizing method for the low bandwidth link according to claim 1, wherein the visible satellite signal is acquired, specifically, the visible satellite signal is captured through an RTK module and a satellite communication antenna, the RTK module completes satellite signal reception, demodulation and spread spectrum recovery, and the original observation data in RTCM3.3 format is output.
3. The NRTK differential data optimization method for the low-bandwidth link according to claim 1, wherein the scoring of the information amount of each satellite is performed on the RTCM differential telegraph protocol frame, specifically comprising: At the single star level, the signal to noise ratio score and the altitude score are divided; The signal to noise ratio score is expressed as: ; Wherein, the Representing the signal-to-noise ratio of a single satellite, Representing the minimum of signal-to-noise ratios for all satellites that can be observed, Representing the maximum value of the signal-to-noise ratio of all satellites that can be observed; The altitude score is expressed as: ; Wherein, the Representing the elevation relationship of the satellite to the initial position; the base score for the final single star level is expressed as: ; Wherein, the Representing the base score for a single star level, And Is the duty cycle weight of the signal to noise ratio and the altitude angle, And Signal to noise ratio and altitude score of single star respectively; At the multi-star level, the contribution degree of a single star on the satellite geometry is obtained, and the geometric contribution degree is expressed as: ; ; ; Wherein, the Representing the geometric contribution of a single star, Representing a certain satellite direction vector used in the averaging direction vector, Representing the set of all of the observed satellites, A direction vector representing a single star is shown, Representing the altitude of a single star, Representing the azimuth angle of a single star, Representing the average direction vector of all satellites that can be observed; the final information amount scoring formula is ; Wherein, the Representing the weights.
4. The NRTK differential data optimizing method for the low bandwidth link of claim 1, wherein the wireless link employs a LoRa-mesh communication network.
5. The NRTK differential data optimizing method for the low bandwidth link according to claim 1, wherein the fusing of the differential correction data and the reduced frame, the performing of extended kalman filtering, and the performing of a least square ambiguity decorrelation adjustment algorithm, the outputting of the final positioning result, specifically comprises: before the extended Kalman filtering is executed, time window constraint matching is carried out, and storage space storage reference station data based on a time window is constructed; When the original observation data arrives, searching the same epoch in a time window of the stored data, if the same epoch is found, using the differential correction data issued by the corresponding virtual reference station, and if the same epoch is not found, using the reference station differential data with the minimum epoch difference value; propagation state covariance at short link breaks, specifically expressed as: ; ; Wherein, the Is a posterior state estimate of time k, Is a posterior state estimate of time k-1, Is the posterior state estimation covariance matrix at time k, Is the posterior state estimation covariance matrix for time k-1, Model imperfections and unmodeled disturbances are described for characterizing the accumulation of uncertainty during an interruption.
6. The NRTK differential data optimization system for the low-bandwidth link is characterized by comprising an edge node, a platform end and a network CORS center; the edge node acquires visible satellite signals and encapsulates the visible satellite signals into RTCM differential message protocol frames; the edge node scores the information quantity of each satellite for the RTCM differential message protocol frame, reserves the observation data of Top-k optimal satellites and reorganizes the frames to form a simplified frame; the simplified frame is sent out by an edge node narrow band antenna, and reaches a platform end in a single-hop or multi-hop mode after being attenuated by a wireless link, so that low-bandwidth backhaul is realized; the platform end performs single-point positioning calculation on the simplified frame to obtain a rough positioning result of the edge node; The platform end uploads the coarse positioning result to a network CORS center, and triggers generation of a virtual reference station request; the network CORS center generates a virtual reference station in the range of the rough positioning point adjacent to the short base line, the virtual reference station generates differential correction data, and the corresponding differential correction data is returned to the platform end; The platform end fuses the differential correction data and the simplified frame, executes the extended Kalman filtering, carries out the least square ambiguity decorrelation adjustment algorithm, and outputs the final positioning result.
7. The NRTK differential data optimizing system for the low bandwidth link of claim 6, wherein the edge node acquires the visible satellite signal, specifically captures the visible satellite signal through the RTK module and the satellite communication antenna, and the RTK module performs satellite signal reception, demodulation and spread spectrum recovery, and outputs the original observation data in RTCM3.3 format.
8. The low bandwidth link oriented NRTK differential data optimization system of claim 6, wherein the satellite-by-satellite information amount scoring of RTCM differential telegraph protocol frames specifically comprises: At the single star level, the signal to noise ratio score and the altitude score are divided; The signal to noise ratio score is expressed as: ; Wherein, the Representing the signal-to-noise ratio of a single satellite, Representing the minimum of signal-to-noise ratios for all satellites that can be observed, Representing the maximum value of the signal-to-noise ratio of all satellites that can be observed; The altitude score is expressed as: ; Wherein, the Representing the elevation relationship of the satellite to the initial position; the base score for the final single star level is expressed as: ; Wherein, the Representing the base score for a single star level, And Is the duty cycle weight of the signal to noise ratio and the altitude angle, And Signal to noise ratio and altitude score of single star respectively; At the multi-star level, the contribution degree of a single star on the satellite geometry is obtained, and the geometric contribution degree is expressed as: ; ; ; Wherein, the Representing the geometric contribution of a single star, Representing a certain satellite direction vector used in the averaging direction vector, Representing the set of all of the observed satellites, A direction vector representing a single star is shown, Representing the altitude of a single star, Representing the azimuth angle of a single star, Representing the average direction vector of all satellites that can be observed; the final information amount scoring formula is ; Wherein, the Representing the weights.
9. The low bandwidth link oriented NRTK differential data optimization system of claim 6 wherein the wireless link employs a LoRa-mesh communications network.
10. The NRTK differential data optimizing system for low bandwidth link according to claim 6, wherein the platform end fuses the differential correction data and the reduced frame, performs extended kalman filtering, performs a least square ambiguity decorrelation adjustment algorithm, and outputs a final positioning result, and specifically comprises: before the extended Kalman filtering is executed, time window constraint matching is carried out, and storage space storage reference station data based on a time window is constructed; When the original observation data arrives, searching the same epoch in a time window of the stored data, if the same epoch is found, using the differential correction data issued by the corresponding virtual reference station, and if the same epoch is not found, using the reference station differential data with the minimum epoch difference value; propagation state covariance at short link breaks, specifically expressed as: ; ; Wherein, the Is a posterior state estimate of time k, Is a posterior state estimate of time k-1, Is the posterior state estimation covariance matrix at time k, Is the posterior state estimation covariance matrix for time k-1, Model imperfections and unmodeled disturbances are described for characterizing the accumulation of uncertainty during an interruption.

Description

NRTK differential data optimization method and system for low-bandwidth link Technical Field The invention relates to the technical field of differential positioning data processing, in particular to an NRTK differential data optimization method and system for a low-bandwidth link. Background The Beidou satellite navigation system has real-time centimeter-level dynamic positioning capability, and can realize millimeter-level displacement monitoring by continuously broadcasting differential correction information to field users through a foundation enhancement network. The existing foundation differential network can also provide a network differential data downloading function, and realize network real-time dynamic differential positioning (NRTK positioning). However, the raw observations of satellites generally grow linearly with the number of satellites in view, and the amount of data is relatively large. In Long-term deformation monitoring of remote scenes such as transmission towers, side slopes, dangerous rooms and bridges, the cost and the power consumption are limited, the sites can only rely on narrow-band wireless links such as LoRa, NB-IoT and BLE Long-Range to carry out back transmission, the air rate of the links is low, the payload of a single packet is small, if the traditional observation data message is directly transmitted in a penetrating manner, transmission queuing, sub-packet retransmission and even data loss are easy to occur, the data of an observation station cannot reach a terminal in time, the whole-cycle ambiguity is difficult to fix, and the positioning result is drifting. In order to relieve bandwidth pressure, simplification means such as thinning visible satellites, reducing precision bits or starting general lossless compression are generally adopted, but the geometric structure of the satellites is usually sacrificed or the operation load of a processor is increased while the flow is reduced, the initial fixed time is prolonged, the re-capturing capacity is finally reduced, the scheme is also adopted, the original observed value is replaced by the state domain parameter, the byte length can be greatly reduced, the terminal is required to additionally support a novel service protocol, and the hardware upgrading cost is increased along with the rise. Therefore, how to smoothly pass through the narrow-band link by the differential data and maintain the centimeter-level positioning precision and the quick re-acquisition performance on the premise of not changing the existing low-cost single-frequency or multi-frequency RTK module hardware and not additionally increasing the power consumption has become a main obstacle for restricting the large-scale application of the Beidou high-precision Internet of things monitoring. Disclosure of Invention In order to overcome the defects and shortcomings in the prior art, the invention provides an NRTK differential data optimization method and system for a low-bandwidth link, which effectively solve the problem that the traditional NRTK positioning is dependent on a high-bandwidth link technology in non-edge solution, and can be widely applied to a non-edge solution scene under the requirements of low cost and low power consumption through a designed data screening and platform end solution optimization method, thereby improving the accuracy and stability of the low-cost positioning technology. In order to achieve the above purpose, the present invention adopts the following technical scheme: the invention provides an NRTK differential data optimization method for a low-bandwidth link, which comprises the following steps: Obtaining visible satellite signals and packaging the visible satellite signals into RTCM differential message protocol frames; scoring the information quantity of each satellite in the RTCM differential message protocol frame, reserving the observation data of Top-k optimal satellites, and reorganizing the frames to form a simplified frame; Performing single-point positioning calculation on the simplified frame to obtain a rough positioning result of the edge node; triggering and generating a virtual reference station request; generating a virtual reference station in the range of the rough positioning point adjacent to the short base line, and generating differential correction data by the virtual reference station; And fusing the differential correction data and the reduced frames, executing extended Kalman filtering, performing a least square ambiguity decorrelation adjustment algorithm, and outputting a final positioning result. As a preferable technical scheme, a visible satellite signal is acquired, and particularly the visible satellite signal is captured through an RTK module and a satellite communication antenna, the RTK module completes satellite signal receiving, demodulation and spread spectrum recovery, and original observation data in an RTCM3.3 format is output. As a preferable technical scheme, scoring the