In a new paper, engineering researchers looked at six satellites to find locations with a resolution of eight metres.
Broadband satellite signals from StarLink can be used to determine the location on Earth with an accuracy of up to eight metres. According to them, part of the growing research is the use of low-Earth satellite (LEO) signals for navigation, similar to how GPS works.
This technology won't soon replace your smartphone's map app, and it looks like this initial test took 13 minutes to track six Starlink satellites to pinpoint a location on Earth. But the researchers were able to get to this site without the help of SpaceX, and they say experience proves that it can be used for navigation.
"The researchers did not need SpaceX to use the satellite signals. They stressed that they could not access real data transmitted via satellite - only access the satellite's location and motion information. They have."
signal, then we designed complex algorithms to determine our location and showed that they work with high accuracy. "Even if the Starlink was not designed for navigation purposes, we've shown that enough parts of the system can be learned for use in navigation," the Ohio State University Center said in an article. Postdoctoral Fellow at the University of California, Irvine) and Muhammad Ninaway (a doctoral student at UC Irvine), Intelligence and Navigation (ASPIN), while Khalifa and Ninawi are members of the lab, which was tested with an antenna at UC Irvine.
“It used constellations of satellites in low Earth orbit, but with less accuracy, pinpointed exact locations 23 meters away, according to the Ohio News article. "The team also worked with the US Air Force to locate aircraft at high altitudes, and they were able to use ground-based cellular signals to reach a distance of 5 meters," Kassas said. GPS provides signals with an average error of less than one meter.
The article “Results of carrier first-stage tracking and positioning with Starlink LEO satellite signals” was published last week in IEEE Transactions on Aerospace. The electronic systems presented to the researchers their findings at the Navigation Institute conference. Their work was funded by research assistance from the US Navy, the National Science Foundation, and the Department of Transportation. Announcement
"Signals of Opportunity"
The researchers' article says that "various theoretical and experimental studies" have considered the possibility of using "opportunity signals" of broadband LEO satellites for navigation. and . .
"With SpaceX launching more than a thousand spacecraft into LEO, the renaissance of LEO-based navigation has begun." "LEO SVs are receiving higher strength signals compared to MEO where GNSS [Global Navigation System] SVs are. In addition, LEO SVs are more powerful than GNSS SVs." They are more diverse in terms of space and spectrum. Another advantage of LEO satellites is that they do not require additional and expensive services and infrastructure. But that doesn't mean it was easy for the researchers. "However, broadband providers typically do not disclose the structure of the transmitted signal to protect their intellectual property. Therefore, it must degrade to plot LEO SV signals to capture navigation feedback," they wrote.
Summary At the researchers' conference, it was noted that broadband providers can change their protocols to support mobility. But the researchers argue that the third-party approach itself is more useful despite the need for a "more complex future architecture".
They wrote that they would not pay private companies such as OneWeb, SpaceX, Boeing and others that plan to launch tens of thousands of broadband satellites into low Earth orbit. "In addition, if these companies agree to the additional cost, there is no guarantee that they will not charge users for additional navigation services. In this case, the use of broadband LEO satellite signals is opportunistic." It would be a more appropriate approach.
The researchers previously considered "a cognitive approach to Doppler frequency tracking of unknown SV LEO signals", but in a recent paper they said this method "cannot detect the carrier phase"., Also, it cannot be accepted here, because it requires knowledge of the light period of the transmitted signal, which is unknown in the case of Starlink LEO SVs." To overcome this obstacle, it's "carrier phase tracking algorithm for "Starlink signals were generated without prior knowledge of their structure."
The article says:
There is little information about Starlink downlinks or their encounters. antennas in general, other than channel frequencies and bandwidth It is not easy to design a receiver to track Starlink signals with the above information as a deeper understanding of the signals is required Software Defined Radios (SDRs) are useful in such situations because they allow you to sample bands of However, there are two main examples of Starlink signal sampling: (1) the signals are transmitted in the Ku/Ka bands, which exceed the carrier frequencies most commercial SDR systems can support, and (2) the link channel bandwidth can be increased Downlink.Up to 240MHz, which exceeds current commercial SDR capabilities.The first challenge can be solved by using a mixer/converter between the antenna and the SDR.However,the sampling bandwidth can only allow as much as the SDR.In general,it does not require opportunistic navigation frameworks a lot of predicate and died from the communication/navigation source (eg, decoding telemetry, transfer data, or synchronization with a given introduction). Therefore, the goal of the receiver is to use a sufficient downlink signal to generate crude navigation vessels (eg, Doppler and carrier stage).
Six satellites tracked for 800 seconds to receive Starlink signals in the Ko group. The sampling bandwidth is set to 2.5MHz and the carrier frequency is set at 11.325GHz, which is one of the frequencies of the Starlink base line. “ p>
The researchers tracked Starlink signals for 800 seconds, about 13.3 minutes “During this time, a total of six Starlink SVs transmitting at 11.325 GHz passed through the receiver one by one,” the researchers wrote. The result was 25.9 meters of Actual location, but with a receiver equipped with an altimeter (to find out the height) the error was reduced to less than eight metres. The article concludes: p>
This character showed the first trace and carrier phase positioning with real Starlink LEO SV signals. The transmitted Starlink SV signal was modeled, and a KF-based carrier phase tracking algorithm (Kalman filter) was developed to track the Starlink signal.Experimental results showed the phase tracking of six Starlink LEO SV carriers over a period of about 800. Second.The positioning function was as follows: 7.7 square meters error D when the receiver height is specified, 25.9 square meters error 2 D and 33.5 square meters error 3D when the receiver height is unknown SpaceX has launched more than 1,700 satellites, but eventually plans to launch tens of thousands to increase capacity and broadband availability . I rode These additional satellites also facilitated the construction of navigation systems of the kind expected in the new research.
We called the researchers today to think about the possibility of using Starlink satellites to obtain location results in the near future and how they could use LEO-based systems for navigation when methods and technology are more advanced. We will update this article if we receive a response.
Researchers use Starlink satellites to locate GPS-like locations
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