"In previous years when sowing, the equipment signals were often unstable, and sometimes there was simply no signal at all," said Master Bai, a corn grower in Tacheng, Xinjiang.
Tacheng is located in the border area of northwestern Xinjiang, where communication network outages frequently occur. The SpatiX Automated Steering System can overcome the problems of missing network signals and insufficient coverage of regional stations, enabling rapid centimeter-level high-precision operations.
Behind this lies the relentless efforts of SpatiX's algorithm engineers on the convergence performance of Satellite-Based Augmentation technology — without relying on satellite navigation regional encryption stations or atmospheric product assistance, they can still quickly and reliably obtain high-precision positioning results, with an average convergence time of 1 minute and the fastest convergence achievable in tens of seconds.
"We call this technology the regional station-free fast convergence PPP technology. Since it does not rely on atmospheric products, it can greatly reduce the global station construction cost and achieve global coverage through dual satellite/network links with a small transmission bandwidth," said a SpatiX algorithm engineer.
SpatiX can provide fast, efficient, and reliable high-precision positioning services anywhere in the world.
SpatiX PPP Technical Performance VS Traditional PPP Technical Performance
Convergence Time: The "Unspoken Worry" of Traditional PPP Technology
The main reason why agricultural machinery autonomous driving equipment relies on networks and regional station networks is that most of them use Real-Time Kinematic (RTK) positioning technology. Although traditional RTK technology converges quickly, its coverage range is still limited. The positioning target must be within the coverage of communication signals, leaving large-scale positioning blind areas in regions such as oceans, deserts, and overseas areas.
Complementary to this is the Precise Point Positioning (PPP) technology. PPP technology摆脱数据传输对于互联网的依赖 by accurately modeling satellite positioning errors and broadcasting them to users, allowing users to obtain precise positioning results through satellite links as well.
However, traditional PPP technology usually requires an initial positioning time ranging from ten to several tens of minutes to converge to centimeter-level accuracy. Such a long time obviously cannot meet the requirements of high-real-time and high-precision application scenarios such as UAV flight control, agricultural machinery navigation, and intelligent driving. How to shorten the PPP initialization time is an important factor in improving user experience.
Shortening Convergence Time: A Contest Against Time
With the improvement of the global networking of the BeiDou Satellite Navigation System and the Galileo Satellite Navigation System, as well as the upgrade of multi-system support for terminal receivers, with the support of PPP ambiguity resolution technology, the convergence time of multi-system PPP technology has been significantly improved, from tens of minutes to the order of ten minutes.
When the industry was generally satisfied with PPP convergence time better than 10 minutes, the SpatiX technical team did not stop there, but considered how to effectively apply multi-system and multi-frequency satellite navigation signals. Based on SpatiX's global reference stations, they continuously made breakthroughs in server-side algorithms and terminal algorithms to improve PPP convergence performance and relentlessly pursue the convergence time indicator.
With the construction of the BeiDou-3 global system, SpatiX has rapidly deployed and established hundreds of reference stations around the world that can support tracking all-system and all-frequency satellite signals of BeiDou-3, simultaneously providing global augmentation services. "With the support of BeiDou's global services and our natural advantage of having global reference stations, we have a strong guarantee for calculating high-precision satellite-side error correction products, which makes us see the possibility of improving PPP convergence performance," said Chang Shengqi, a SpatiX algorithm expert.
With the support of global reference stations, at the server-side algorithm level, high-precision satellite orbit and clock offset products are the foundation for achieving fast PPP convergence. Especially for BeiDou-3, a brand-new navigation system, accurately modeling the satellite's attitude change laws and the solar radiation pressure it receives is a great challenge. By tracking academic frontier developments and combining long-term tracking data from SpatiX's global reference stations, SpatiX's algorithm experts have conducted in-depth research on the movement laws of BeiDou-3 satellites, establishing high-precision satellite attitude models and solar radiation pressure models, laying the foundation for the calculation of high-precision satellite orbit and clock offset products.
Multi-frequency and multi-system satellite hardware delay products are also important modules for achieving fast PPP convergence at the server-side algorithm level. Thanks to the Qianlong Space-Time servers with unified hardware configurations, the satellite hardware delay products calculated by SpatiX are more stable and accurate. In addition, to maximize the effect of fast convergence, the cloud-integrated PPP engine plays a key role.
Delivering the above server-side products to users in the shortest time is crucial for users to obtain the best PPP fast convergence experience. "SpatiX's global reference stations transmit data back through dedicated lines, which greatly ensures the 'freshness' of observation data. With the ability to quickly process massive amounts of data, a distributed parallel algorithm scheduling architecture, and a flexible and efficient transmission link design, service products can be delivered to users via geosynchronous satellites in just a few seconds," said Chen Jianbo, a senior technical expert at SpatiX.
With complete and reliable server-side algorithm products and a flexible and efficient transmission link design, how to achieve ultra-fast PPP convergence on the terminal side? The terminal algorithm team has explored new technical paths from two aspects: multi-frequency observation application and PPP ambiguity resolution to improve convergence performance.
Firstly, at the level of multi-frequency observation application, combining the multi-dimensional spatiotemporal data accumulated from different geographical environments by the national BeiDou ground-based augmentation system "one network", a set of adaptive multi-frequency observation models has been developed, which can adaptively adjust the observation model according to the actual frequency type, observation noise and other characteristics.
Secondly, at the level of PPP ambiguity resolution, combining the accuracy and delay of satellite-based corrections, the random characteristics of observations, observation residuals, etc., various methods including empirical model optimization and machine learning have been tried for ambiguity confirmation, forming a PPP ambiguity resolution model adapted to satellite-based corrections broadcast via satellite links, ensuring that the terminal can still obtain reliable positioning results when satellite link signals are temporarily blocked or interfered.
Operation and Maintenance Monitoring: Maintaining Stable Convergence Performance
6 minutes, 3 minutes, 2 minutes, 1 minute... Each improvement in speed is a motivation for further breakthroughs. Through repeated technical iterations and attempts, SpatiX has stabilized the average convergence time at around 1 minute, with the fastest taking only tens of seconds. The greater challenge ahead is how to maintain the stability of convergence performance.
On the service side, through more than 6 years of service experience, SpatiX has accumulated rich service anomaly monitoring methods, establishing a complete operation and maintenance monitoring system from multiple dimensions such as base station data, satellite status, product accuracy, and link delay, ensuring the stability of service product calculation and data transmission.
On the product terminal side, based on independently developed satellite-based modules, boards, complete machines and other equipment, a complete monitoring system covering research and development, testing, pre-sales, and after-sales has been established. Through the accumulation of a large number of application scenarios and cases, continuous iterations and upgrades are made at the terminal algorithm level.
High-precision positioning services can be obtained within seconds anywhere in the world. The breakthrough in PPP convergence speed enables more efficient operations in high-real-time and high-precision application scenarios such as automated agriculture, marine surveying, and UAV inspection, and also provides broader space for the global application of satellite navigation technology in fields such as intelligent driving.