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Arthur T Knackerbracket has found the following story:
The BeiDou global navigation satellite system (BDS-3) was formally commissioned to provide positioning, velocity, and timing services to global users on 31 July 2020.
Researchers from the Time Keeping Laboratory, the National Time Service Center (NTSC) of the Chinese Academy of Sciences, analyzed the time transfer performance of BDS-3 signals and found that it was over 50% higher than that of the BDS-2 satellites. The elevation-dependent biases found in BDS-2 code measurements are mitigated in BDS-3.
The results were published in Metrologia on Oct. 28.
Journal Reference:
Wei Guang et al. Analysis on the time transfer performance of BDS-3 signals, Metrologia (2020). DOI: 10.1088/1681-7575/abbcc1
(Score: 3, Informative) by janrinok on Saturday November 07 2020, @08:53AM (7 children)
As mentioned in TFA, this brings the accuracy of the Chinese system to similar levels as GPS and Galileo. While this might eventually give the world another source of positioning data - and more is better, right? - it would also give the Chinese an independent system for use in their weapon systems.
(Score: 0) by Anonymous Coward on Saturday November 07 2020, @12:02PM (1 child)
A tool is a tool is a tool.
(Score: 0) by Anonymous Coward on Saturday November 07 2020, @12:07PM
i get blisters from some tools.
some tools also make heads roll and others are so powerful and MAD that they can enforce a monetary society based on debt ...
(Score: 2) by takyon on Saturday November 07 2020, @01:45PM (1 child)
What's wrong with that? Is China ready to start waging war in Africa for resources?
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by janrinok on Saturday November 07 2020, @04:00PM
No, but in times of conflict the US can degrade public access to GPS should it wish to do so, although it would surely to be aware of the widespread problems that would ensue. LIkewise, Russia probably has the same ability with GLONASS. For global use the Chinese currently have to rely on their own, less accurate, system or use the system of one of the two other major players. With this enhanced system they will have a purely national system of similar accuracy.
Whether they are about to use it today isn't the issue. We keep close eyes on all weapon developments worldwide - one never knows who will be your enemy tomorrow. For example, during the Gulf war we found ourselves on the receiving end of western weapon systems. There was significant difficulty getting hold of sensitive frequencies and war-only settings from our allies, let alone those of systems from potential enemies.
(Score: 0) by Anonymous Coward on Saturday November 07 2020, @02:10PM (2 children)
Remember, this has always been the first and original goal of GPS systems.
(Score: 0) by Anonymous Coward on Sunday November 08 2020, @01:33AM (1 child)
No. [esa.int]
(Score: 2) by janrinok on Sunday November 08 2020, @12:28PM
TIMATION was an essential stage in the development of GPS - without the super accurate clocks the positional calculations are not possible. Getting the clocks into space and proving the theory was the purpose of TIMATION, but that was not the ultimate aim of the system development. It was, as the linked article you provided states, a 'navigation test system'.
GPS was always intended primarily for military use to improve navigational accuracy for the military, particularly for rapidly maneuvering platforms. This was particularly important in intercontinental and long-range weapons where reducing the Circular Error Probable (CEP) of individual warheads with independent guidance capabilities was vital for multiple warhead systems. Such weapons include aircraft, missiles, etc. It has made possible systems such as cruise missiles because inertial systems just could not provide the accuracy required for precise delivery of a relatively small (often conventional) warhead which is nowadays deemed essential.
If you recall, the initial accuracy of GPS was degraded when it first became available for non-governmental use, although the military always had an encrypted mode with maximum accuracy. Now even terrorists and insurgents use the technology to deliver weapons e.g. the use of commercial drones in the Middle East.
(Score: 2) by hendrikboom on Saturday November 07 2020, @02:42PM (4 children)
What is time transfer performance? And what is time transfer?
(Score: 3, Informative) by VLM on Saturday November 07 2020, @03:35PM (3 children)
Disclaimer: I've fooled around a lot with GPS and GNSS technology for the sheer hell of it, familiar with the time nuts list although wouldn't consider myself a member, and only tangentially did datacenter type stuff with GPS clocks.
So you wanna know what time it is. The standard metrology way is you set up your best local clock system in the lab that you'll actually use day to day, nanosecond to nanosecond. Then international researchers have had the tech for "a long time" to watch multiple GNSS systems and compare their multiple satellite signals to your local best attempt clock. There's even a standardized file format CGGTS to log the time offset comparisons and share worldwide over the internet. Then you run the comparison test data thru a continuously evolving software suite and it compares ALL the clocks from ALL the satellites along with your clock and squirts out various performance stats generated by rubbing each clock up against every other clock. More or less. Then you log the calibration values for your best attempt clock. Note that "your clock" is probably a prime number of distinct clocks that you can rub together vs historical data (remember those CGGTS files?) to always locally be able to output a best guess time, the offset from the official time at this instant, and some std deviation type predictions WRT accuracy. Now recalibrating one of your clocks means tossing its historical performance data so as usual in metrology you change as little as possible as rarely as possible but it does happen. Better to rub a constant, well known, repeatedly measured ppb or whatever vs the other clocks than to try to F with a clock resulting in some new random drift value that isn't characterized yet and can't be for a year or years. Ah the joys of metrology.
So that's time transfer. Transfer the shared multiuser hallucination of what real time is, using sats we can all see at the same time, more or less. We all see "about" half the GPS satellites at a time (not really due to horizon effects and multipath and the altitude of the sats is not infinite etc) but anyway as a worldwide thing with multiple systems we can figure out the shared multiple source GNSS world time and transfer that to generate calibration data on our local clocks. Then we can beat the hell out of our local clocks however we wish and apply the recorded calibration data to output the corrected "real" time however we wish along with some pretty accurate estimates of how far off our local clock is.
Maybe a crappy SN automobile analogy is time transfer is we don't really know the length of our F-150. But periodically we could visit dealerships and compare the length of OUR F-150 to various individual samples of Priuses (priis?) and geo metros and Dodge Aspens and Ford Country Squires and Ford Fairmonts and all kinds of nonsense generating a vast list of comparisons of the length of our truck vs the length of numerous other vehicles. And by comparing our ratios and agreed upon dimensions with numerous world wide researchers some comparing to the same individuals as we used, we could determine our particular example of a F-150 is exactly 209.10006 inches long. Now we could divide our F-150 by 209.10006 and have a pretty darn accurate standardized inch. And that would be "length transfer" as opposed to "time transfer" but whatever. Maybe we could make an even shittier analogy using idle RPMs because RPM is kinda a time transfer. Google says the 2017 F150 idle target is 653 rpm which is ridiculously inaccurate given that its engine computer probably uses a cheapie 100 ppm canned oscillator.
Anyway for whatever reason the Chinese -2 sats were rubbed up against every other sat out there and they were kinda poor std deviation results compared to all the -3 sats that have better results.
If you'd prefer a NTP analogy, its as if for no apparent reason given a population of NTP clients at level 3 or whatever, maybe a subpopulation of some peculiar intel chipset always give worse performance when comparing numerical stats vs all the other level 3 NTP clients. Weird.
Why did series -2 sats have that error, donno. Why didn't it get corrected in software / firmware, donno? Donno if anyone knows. I don't have gear at this moment to test Chinese sats with. The end result however is as a system -3 sats actually work. Interesting.
As a side note its very easy to get shitty low performance NEMA strings for no cost, practically, but "real GPS gear" rapidly become hard to obtain, use, and acquire.
(Score: 0) by Anonymous Coward on Sunday November 08 2020, @01:46AM (1 child)
Because like everything else, when China gets into some new technical area, they don't know what they're doing and they "buy, copy, or steal the technology they need. [reuters.com]". It was a shitty knock off, but they stole enough information and hardware to respin it into the next version.
On the receiver side, the hardware is getting easier and easier to achieve, and much much cheaper, but even now the high end geodetic receivers have a lot of "black magic" in their innards. The people who work on RINEX data conversion software have had to reverse engineer, etc., when the hardware vendors were less than straightforward. But those little GPS chips you can purchase from Adafruit or Sparkfun do amazing things that you wouldn't have had access to 10 years ago (PPS signals out, etc.)
(Score: 2) by VLM on Sunday November 08 2020, @03:00PM
You'd think there would be more action on the GNURADIO front but there is not.
One of those "in my infinite spare time" projects.
(Score: 2) by hendrikboom on Sunday November 08 2020, @12:51PM
I see. Thank you.
(Score: 0) by Anonymous Coward on Saturday November 07 2020, @04:20PM (1 child)
Netcraft confirms it.
(Score: 2) by jimtheowl on Sunday November 08 2020, @06:59AM