Ship-borne medium-pass antenna for fishing boats
Beidou navigation system
Calling, sending friends, brushing Weibo, watching videos, today's mobile phones have become part of our lifestyle. But in the sea without network signals, these seemingly ordinary habits are a luxury.
The fishermen go fishing in the sea and can only contact the relatives on the land by maritime satellite phone. The high amount of telephone charges can not afford the fishermen to consume, and the mobile phone has become a "display".
But now the fishermen in Zhoushan, Zhejiang, are very happy. They only need to install a silver-and-white, pot-like product on the ship. When the fishing boat is sailing on the sea, the communication terminal can receive the signal from the satellite. Converted to WiFi signal, then you can directly enjoy the Internet, watch live video, use WeChat, and the cost is still very low.
"This 'pot' is called the ship-carrying antenna." The project leader and general manager of Beijing Xingwang Weitong Technology Development Co., Ltd. Xu Wei told reporters that the antenna can realize real-time, high-bandwidth and uninterrupted transmission. Multimedia information such as images, video and voice is the best choice for emergency communication, mobile communication and communication in remote areas.
In recent years, the R&D team led by technical talents such as Xu Wei and Zhang Zhongyi, independently developed their own tracking and pointing system based on inertia/Beidou based on their technical advantages in the fields of Beidou and inertia, breaking through the movement. Key technologies such as automatic satellite finder technology, low-cost inertial attitude measurement technology, and dynamic antenna tracking technology have effectively improved product performance, greatly reduced the cost of use, and promoted the industrial application of mobile satellite communication antennas. In the 2017 Beijing Science and Technology Awards, the project won the second prize.
Develop a cost-effective servo tracking system
"The user you are calling is not in the service area." In life, we occasionally encounter such a situation because there is no communication signal, but in the face of satellite communications, this is not a problem.
"The so-called high station can be seen far away", which is different from the coverage of terrestrial mobile communication networks. Satellite communication is not affected by the ground environment, and you can freely communicate with the outside world wherever you are.
Especially when natural disasters such as earthquakes, floods, typhoons, etc. occur, conventional ground communication may be destroyed, often leading to communication congestion, congestion, interruption, paralysis and other communication barriers. The disaster information cannot be quickly and accurately obtained, to a certain extent. It restricts emergency command and decision-making. Therefore, it is necessary to build a satellite communication system that is flexible, safe, reliable, and moderate in scale.
The moving antenna is the use of geosynchronous satellites as a transit station. It can still accurately align the satellites in the sky in real-time mobile carrier platforms (such as moving cars, boats, airplanes, etc.) to achieve high reliability. High bandwidth communication. It is understood that the current mobile antenna has become an indispensable key product in mobile satellite communication terminals.
"The shortage of satellite resources in the sky and the high price and reliability of terrestrial communication terminals have restricted the development of broadband satellite communication to a certain extent." Xu Wei said.
It is reported that the premise of broadband satellite communication is that the satellite antenna on the ground always accurately points to the communication satellite in the sky, but in the process of moving the ground carrier, due to changes in its attitude and geographical position, the original satellite antenna will be deviated from the satellite, so that communication Interrupted, so these changes in the carrier must be isolated so that the antenna is unaffected and always aligned with the satellite.
"Moving carriers need to track the satellites without interruption, which is very difficult, just like the tip of the needle to the wheat," Xu said.
In addition, the high cost also limits the development of satellite communications. Among them, the servo tracking system is the key to technology and the most costly place. Xu Wei told reporters that there are two solutions for the general servo tracking system. The first method is high-precision fiber-optic inertial navigation. Although the measurement accuracy is very high, the cost is extremely high, and it is difficult for general users to bear. The fishermen can only hope to sigh. The second way is to use low-cost MEMS gyro plus satellite beacon signals to pass the beacon. Signal correction improves system accuracy, allowing the system to significantly reduce overall cost while ensuring tracking performance.
“The positioning attitude measurement system, mechanical transmission system and stable tracking system account for about 70% of the total cost of the antenna. Our research and development idea is to develop a cost-effective servo tracking system.” Xu Wei introduced.
Innovative stellar algorithm
The traditional satellite antenna mainly relies on the position and attitude angle information given by the high-precision inertial navigation system to calculate the antenna's homing command angle, thereby controlling the antenna to align with the satellite.
However, this kind of scheme has higher requirements on the inertial navigation system. In order to ensure that the antenna can lock the largest satellite signal, the independent northing precision of the inertial navigation system must reach 0.1° or more, and the cost of such a high precision inertial navigation system is far. Far beyond the cost of the mobile satellite communication antenna itself, which is unaffordable for most development units and users.
"In order to effectively reduce the cost, a low-precision inertial navigation system must be selected, and the low-precision inertial navigation cannot independently search for the correct heading. Therefore, the antenna cannot obtain an accurate star command angle." Xu Wei said.
In order to solve the problem of initialization of mobile satellite communication antenna based on low-precision inertial navigation, most of the development units currently use antenna azimuth axis 0°-360° scanning plus satellite beacon signal peak identification technology to realize antenna homing, but not very well Solve the problem of how the moving antenna can use the auxiliary information of the stellar star to calculate the initial heading of the inertial navigation system in different attitudes.
"At present, the existing methods mainly adopt the plane solving algorithm, and the estimated homing navigation error is large, so that the tracking performance of the mobile satellite communication antenna is greatly reduced." Xu Wei said.
In response to the above technical problems, the R&D team proposed an initialization method for a mobile satellite communication antenna, which uses the antenna azimuth axis 0°-360° scan to find the satellite, and then estimates the low through a complete three-dimensional coordinate transformation plus an iterative progressive algorithm. The initial heading angle of the precision inertial navigation system. Because this method has better environmental adaptability, it can be applied to the initial star-seeking process of the carrier at any attitude angle. After the initialization, the initial heading accuracy of the inertial navigation system estimated by using the satellite-assisted information can reach 0.1°. the above.
"Compared with the existing initialization algorithm based on plane coordinate estimation, the proposed method can accurately estimate the initial heading of the carrier inertial navigation system in any attitude environment, thus ensuring that the antenna can accurately track the satellite after the initialization is completed." Xu Wei said.
At the same time, the project team innovatively designed an integrated method of Beidou/inertial integrated navigation and servo stability tracking to improve system integration and control accuracy. The traditional integrated navigation system is generally solved as a separate component by outsourcing. The attitude measurement and servo control operate independently as two subsystems. In this way, problems such as large delay of the servo system, poor synchronism, divergence of open-loop control error, and the like, and the system control accuracy cannot be improved under high dynamic conditions.
In response to this problem, the R&D team uses a single CPU to realize the integrated operation of the navigation algorithm and the control algorithm, which reduces the delay of data interaction between the navigation system and the control system, greatly improves the bandwidth of the control system, and solves the problem that the tracking accuracy of the high dynamic environment is difficult to improve. Puzzle.
System performance is better than the leading international products
“The performance of this system ranked first in a national public bidding test, and the system performance is comparable to that of the international leading products.” Xu Wei proudly said.
It is understood that Beijing Xingwang Weitong Technology Development Co., Ltd. has developed nearly ten different models of new products, which have achieved good market share in emerging markets such as marine fishing vessels.
“Our products have been used in many industries and units.” Xu Wei said, “In the Sichuan Lushan earthquake that occurred in 2013, our 'Zhongzhongtong' satellite communication vehicle can be in real time in the case of terrestrial communication systems. The site transmits images, voices and data to the ground command center."
At the same time, the high-precision Beidou navigation system provides high-precision positioning navigation information for various mobile satellite communication devices such as mobile communication and portable stations, and integrates satellite beacons and inertial navigation technology to achieve high-precision satellite tracking and servo stabilization. performance. The initial star time is shortened, the tracking accuracy is improved, and the dependence on GPS and other satellite navigation systems is completely eliminated.
The integration application of Beidou navigation system and satellite communication system has created a new way to promote the industrial application of high-precision Beidou navigation system. The high-precision Beidou navigation system has been applied in batches in high value-added and high-tech industrial projects.
In recent years, Beijing has implemented a series of support policies in terms of market access, factor supply, cost reduction, property rights protection, and public services to encourage, support and guide the sustainable and healthy development of the private economy. A group of private technology enterprises represented by Beijing Xingwang Weitong Technology Development Co., Ltd. ushered in an important period of development opportunities, and showed outstanding features such as strong strength, vitality, new business, great contribution and wide radiation. An important force driving the quality of the capital. (Reporter affirmed)
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