With the advancement of the Internet of Things, the requirement for location services is on the rise. Numerous organizations predict that a significant 60% of IoT devices will depend on geographical location data. Particularly, the market for extensive outdoor positioning is set to become an unignorable sector.
In the realm of navigation technology, a highly esteemed club known as the Global Navigation Satellite System (GNSS) has emerged. Despite its small membership of only four, this club has managed to captivate the interest of heads of state and garnered extensive research from top scientists and engineers. The esteemed members of this club include the American GPS, European GPS (Galileo GALILEO), Russia's GLONASS, and China's Beidou COMPASS.
China's Beidou system has recently joined the ranks, establishing itself as the most rapidly advancing member. What is the current progress of Beidou? How does it influence our lives? This captivating topic has piqued considerable interest. Although academic journals feature numerous articles on Beidou, the excessive use of technical jargon alienates and discourages the average reader.
Block GPS signal
The expanding GPS locator market has led to a notable increase in the number of individuals who desire to evade GPS signal tracking. Consequently, these individuals are actively searching for products known as GPS signal jammers, which can effectively block the tracking of GPS signals.
The gps jammer is capable of effectively obstructing the GPS locator. When a jammer is employed, it disrupts the regular operation of the GPS locator, resulting in incomplete transmission of data to the locator monitoring platform. Similar to a mobile phone, the GPS locator requires the insertion of a mobile phone card or IoT card to transmit data. Hence, as long as the GPS signal jammer can impede the signal transmission of the mobile phone card, it can effectively block the GPS locator.
The anti-location jammer disrupts the GPS locator by emitting radio interference waves within a specific electromagnetic band. This generates an electromagnetic environment that mirrors the signal-blocking device, effectively blocking GPS satellite signals. As a result, data transmission to the platform is prevented, rendering the device offline and unusable.This device is designed to efficiently block positioning signals, including GPS, Beidou, and base stations. It operates at a transmission power of 5W and offers an adjustable effective shielding distance of 1 to 15 meters (pre-set during manufacturing). By effectively blocking the GPS locator within the vehicle space, it ensures non-functionality without causing any harm to individuals.
Start with GPS
The space century for humanity commenced on October 4, 1957, with the Soviet Union's successful launch of the world's first artificial earth satellite. This event captured the close attention of the United States. Within Hopkins's Applied Physics Laboratory, mathematician Bill Guy and physicist George Weifenbach made a discovery of great significance. They observed a phenomenon where the frequency of this satellite had undergone a shift, later identified as the Doppler shift effect resulting from relative motion.
When deciding on the most suitable orbit for the satellite, three options are available: low, medium, or high. Opting for a low orbit would result in lower launch costs and improved accuracy. However, it is important to consider that achieving global coverage would require the deployment of 200 satellites.
Theoretically, global coverage can be achieved by deploying three satellites in a high orbit. Nevertheless, the launch of high-orbit satellites presents considerable difficulties, and the primary issue lies in the reduced accuracy of positioning. This can be attributed to two key factors: the excessive altitude of the orbit, resulting in significant errors, and the minimal relative speed between the geostationary orbit and ground objects, which hampers the practical implementation of the Doppler frequency shift solution method.
A medium orbit serves as a viable compromise, demanding a mere 24-36 satellites to achieve global coverage. The significant relative speed between the satellite and stationary ground objects enables the effective utilization of the Doppler frequency shift method.
Drawing upon the extensive deliberations mentioned above, the United States made the strategic choice of deploying a constellation of 24 satellites in a medium orbit. The inaugural satellite was successfully launched in 1978, and the complete system was put into operation in 1995. At present, there are 30 satellites, categorized into two distinct positioning modes: military and civilian. This approach embraces a global perspective.
Beidou generation criticized
After the loss of MH370, a lot of popular science appeared, making the public familiar with the term Doppler effect. Is the Doppler effect a good thing or a bad thing for satellites? It depends on what kind of satellite it is. This is a good thing for navigation and positioning satellites, because the greater the relative speed of the satellite relative to the measured object on the ground, the more obvious the Doppler effect, and the positioning will be more accurate. This is even the core principle basis for positioning navigation satellites.
However, the Doppler effect is a bad thing for communication satellites, because the frequency offset will cause communication failure and must be corrected. For example, the Asia-Pacific International Communications Satellite located over the Indian Ocean is fixed relative to the ground. The seven search signals sent by the missing MH370 in the final stage were measured by this satellite and found a frequency offset. This was originally data that was to be corrected, but it was not Thinking of this, it became the only evidence to speculate on the aircraft's trajectory. To sum it up in one sentence: Using communication satellites to position satellites has turned the Doppler effect, which was originally a bad thing, into a good thing.
The scale of Beidou II is similar to that of GPS, and the applied orbit and frequency are relatively consistent with those of European Galileo. This inevitably encounters the problem of competition for satellite orbits and frequencies. Satellite orbits and space frequencies are resources shared by mankind, so how should they be distributed? International rules do not divide them by country or population, but whoever takes advantage first will get it.
In 2005, the first satellite of the Galileo project was launched, but it was not activated. It only occupied the orbit but not the frequency. Why was it not activated? The reason was that there was no money, and activation required money, and Europe was a little tight on money. The first star of China's Beidou II generation also went up to the sky, and it was opened as soon as it went up. Now the orbit and frequency are occupied.
Galileo in Europe was tinkering slowly, while Beidou in China kept launching satellites one after another, and later even built a double satellite. Some frequencies of the Galileo project and Beidou II overlap, and both sides are in the field of international telecommunications. The alliance has been registered, and whoever gets it first will get it. China's fast pace has made Europe anxious, and it has put pressure on China through the United States, asking China to slow down and wait for the European people.
