Should Beidou satellites be blamed for Beidou disconnection? Experts explain

Recently, the incident in which a large truck was fined because the Beidou satellite positioning driving recorder it was carrying was offline has aroused great social concern.

Why did the positioning driving recorder, which is a vehicle terminal, lose the line? Are similar incidents sporadic or frequent? Should the Beidou satellite be blamed for the "Beidou line loss"? Science and Technology Daily interviewed Wu Caicong, associate professor and doctoral supervisor at the School of Information and Electrical Engineering of China Agricultural University.

A variety of factors may cause satellite positioning or data transmission interruption

In an interview with Science and Technology Daily, Wu Caicong said: "It is certain that there is no problem with the Beidou system, because my country monitors Beidou satellites in real time, and any problem with any satellite will be known immediately. If a Beidou satellite does fail, it will not affect only one device."

"The Beidou satellite positioning driving recorder is not the same as the Beidou satellite navigation system." Wu Caicong told reporters that the Beidou satellite positioning driving recorder is a terminal product of the user segment of the Beidou satellite navigation system. It receives satellite signals from the space segment to calculate the user or carrier's navigation and positioning information such as date, time, coordinates, heading and speed.

Vehicle supervision and services are mainly achieved through satellite positioning devices and satellite positioning system platforms. "The positioning device has a built-in SIM card, and the data collected by the positioning device is transmitted back to the positioning system platform through the mobile communication network. Any problem in any link, such as software or hardware failure of the positioning device, communication interruption caused by passing through a blind spot or SIM card arrears, server failure or power failure, positioning system platform failure, etc., as well as human obstruction, power failure or damage, will cause disconnection. After the positioning device is disconnected, the supervisor will not be able to track the real-time location of the vehicle through the positioning system platform, nor can it replay its historical trajectory." Wu Caicong said.

Human influence can also directly interrupt satellite positioning or data transmission. For example, blocking the positioning antenna with an object, installing a "switch" between the positioning antenna and the positioning device, cutting off the power supply of the positioning device, unplugging the SIM card, etc., can cause human failure of the positioning device. The appearance of these human failures is the same or similar to the appearance of device failures, which often makes it difficult for law enforcement personnel to accurately identify the exact cause of the failure.

Both the positioning device and the platform must meet relevant standards

Although the reason why the driving recorders of large trucks were disconnected is still unclear, the phenomenon of unqualified sampling inspections of on-board terminal products is still worthy of attention.

The results of the 2020 quality supervision spot check of Beidou navigation on-board terminals for road transport vehicles announced by the General Office of the Ministry of Transport in December last year showed that in 8 provinces and cities, 30 batches of products produced by 27 companies were sampled, and 19 qualified samples and 8 unqualified samples were finally determined. The main unqualified indicators were positioning function, blind spot reporting function, sleep function, CAN bus data upload, route deviation reminder, etc. The sampling pass rate was 70.4%.

Article 8 of the "Measures for the Dynamic Supervision and Management of Road Transport Vehicles" stipulates that the satellite positioning system platform and vehicle-mounted terminal of road transport vehicles shall pass the technical review of standard conformity by relevant professional institutions. The Ministry of Transport shall issue an announcement for the system platform and vehicle-mounted terminal that have passed the technical review of standard conformity.

"Satellite positioning devices must comply with the industry standards of the Ministry of Transport, as well as relevant national standards, and must pass technical reviews by relevant professional organizations," said Wu Caicong. "The technical review before leaving the factory is only a basic check on the functions and performance of the positioning device. The quality of the positioning device depends on its service life and reliability."

"It is worth noting that the relevant methods and standards do not clearly stipulate the minimum service life of the positioning device. Only factory inspection of the positioning devices provided by the manufacturer cannot truly reflect the quality and reliability of the positioning device." Wu Caicong reminded.

Wu Caicong believes that the relevant industry and national standards must be followed between positioning devices and positioning platforms, and between positioning platforms, to ensure that positioning devices developed by different manufacturers can be connected to positioning platforms developed by different manufacturers. Since the standards stipulate basic technical requirements, positioning device manufacturers and positioning platform manufacturers can also expand the corresponding standard protocols according to their own technical conditions and application requirements, but this does not hinder the data transmission between positioning devices and positioning platforms and the data exchange between multiple positioning platforms.

Strengthen the quality identification and spot check of positioning devices and platforms

"Beidou-based vehicle dynamic supervision plays a very significant role in improving transportation safety and efficiency. It is currently a more efficient and feasible means, and has greatly reduced serious and major casualties caused by fatigue driving, speeding, illegal parking, etc." Wu Caicong said.

Regarding the problem of disconnection of driving recorders, he suggested that we should strengthen the quality appraisal and spot checks of positioning devices and positioning platforms, formulate a corporate blacklist and exit mechanism, and effectively improve the quality of positioning devices and positioning platforms; improve the fault warning methods of positioning devices and positioning platforms, and adopt various methods to ensure that drivers and supervisors are notified, so as to promptly troubleshoot device or platform faults; and for special situations such as being unable to enter service areas in time due to traffic jams, being unable to stop for rest due to special terrain such as rugged mountain roads, and entering communication blind spots and sections where signals are easily interfered with, we should carry out classification, research and disposal of special scenarios for satellite positioning applications.

"In addition, we should promote traffic violation penalties and administrative review mechanisms based on Beidou positioning data, develop corresponding software platforms and apps, and let the data speak for itself," said Wu Caicong.