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Russian GPS Alternative Near Completion
Posted by
ScuttleMonkey
on Wed Dec 26, 2007 03:17 PM
from the better-late-than-never dept.
from the better-late-than-never dept.
Russia has successfully launched another round of GLONASS satellites bringing the grand total to 18 of the navigational units online. "The GPS competitor -- first begun in the Soviet era and only recently revived after years of post-collapse neglect -- is now theoretically capable of providing coverage to the entire Russian territory, with First Deputy Prime Minister Sergei Ivanov claiming that the first compatible consumer devices will be available in the middle of next year. By 2010 Russia plans to open the system up to outside nations as well, contributing to an eventual three- or even four-system global market"
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Required, Sorry (Score:3, Funny)
Re:Required, Sorry (Score:4, Interesting)
Parent
Re:Required, Sorry (Score:5, Informative)
The USA is rolling out their next gen GPS, - M-Code. It gives the US the ability to control accuracy on a 'per nation' basis. (unlike the old way under C/A code where inserted inaccuracy it was regional), or the current P-code (where i believe it is all or nothing - its just whether you have the codes or not.)
These days its just* a matter of adding another receiver card. As long as your system can combine the multiple nav sources (say through Kalman filtering) the more the better. - losing one source doesn't affect you too much.
* in this game 'just' costs about $50K per unit.
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Re:Required, Sorry (Score:4, Informative)
C/A : By altering timings (jitter) on a few satellites, say when they are on the opposite side of planet from the USA, then the regions which use those satellites will have degraded GPS. (GPS being based on precision timing / radio ranging etc. Also important to note that most GPS receivers tend to ignore the strongest Satellites (the ones overhead) so it's the satellites nearer the horizon that provide the most accuracy - so some boffin had to work out a nice algorithm where a lat/long could be entered and an area within a few thousand miles would have degraded GPS. Problem was that airlines who fly world wide were affected by this, thus good 'ol Bill Clinton got the S/A turned off.
M-code: essentially uses public/private key encryption with every nation issued a different key for essentially different virtual circuit. The US can deny service or degrade any one feed selectively. - or more likely offer 'tiered' services where those most friendly nations (UK,AUS) can have accuracy for weapon delivery, and those other 'friendly nations' (don't forget Poland), have 'meh - slightly better than C/A but not good enough for weapon delivery).
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Re:Required, Sorry (Score:4, Informative)
Parent
Re: (Score:3, Informative)
About the article, I'm glad to have GLONASS come out on consumer devices. I use a GPS/GLONASS hybrid receiver for land survey and constructi
So... (Score:3, Insightful)
A man with one clock... (Score:2, Funny)
I suppose if every one of these systems provides a precise enough location, for most purposes it won't matter if they all conflict with one another by a meter or so.
Re:A man with one clock... (Score:5, Informative)
Secondly, while GPS and GLONASS use different terrestrial reference frames, there exists a well defined transform between the WGS-84 used by GPS and the PZ-90 used in GLONASS.
Finally, in a combined GPS/GLONASS receiver it is not optimal to calculate a separate position solution for each constellation. If you track a few more satellites, you can solve directly for the clock offset between the two navigation systems and treat the range measurements as if they were all from one giant 60 satellite constellation. This actually gives you much better satellite geometry, and is often more accurate than any single navigation system on its own.
There is much research being done on the effects of combined constellations with GPS,GLONASS, Galileo and the Chinese Compass system.
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Re:A man with one clock... (Score:5, Interesting)
When I was doing more of this stuff, clients would sometimes take several GPS points, and find to their delite that nearly always the three points were much closer than the supposed precision of plain old non-differential GPS. As a result, they began to assume the system had more precision than rated.
Intrigued by this I set up a fixed station that tracked all the fixes coming out of the receiver over several hour period. What I found is that sequential readings tended to be strongly correlated to their immediate predecessors but weakly correlated to fixes taken much earlier. Essentially the receiver would report all the points as being in a smallish bucket a couple of meters wide, but every fifteen or twenty minutes it would pick up the bucket and put it a different place five or even ten meters away. Then there'd be a run for fifteen minutes or so at the new "bucket position", after which the bucket would move once again.
The way I interpret this is that the various sources of error change as a satellite's position changes. Perhaps a mountain range gives a strong reflection in one position or not another, or perhaps a new satellite rises (or an old one sets), leading to a whole new set of data.
So, it stands to reason that having more than twice the number of satellites means that the various random sources of error would tend to be averaged out more, provided any difference between the old and new system could be accounted for systematically.
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Re:A man with one clock... (Score:4, Informative)
Hmmm, that's odd. I would expect to see this behavior if the GPS was trying to resolve the integeter ambiguity of the phase measurement. Survey-quality receivers do this by using both GPS frequencies in combination with corrections from a reference GPS receiver at a previously surveyed position. Any GPS can trivially determine the fraction of the phase cycle between it and the satellite but must determine the number of cycles via statistical methods using good quality measurements and initial guesses. If this number is estimated correctly, the distance between the satellite and receiver is known to within a couple of centimeters instantaneously.
These integer ambiguities are solved for at least 4 satellites simultaneously. There are always several combination of cycle counts that will result in a good position. However, these candidates may be several meters apart. If the initial guess is wrong, it may be several minutes before a new candidate is chosen and then the switch is instantaneous (hence the jump you observed).
I didn't think a consumer single-frequency receiver could do this, even with WAAS. I would expect a single-frequency receiver to simply drift around the true position without any sudden jumps (assuming there are at least 5 satellites visible at any given point in time and there aren't any strong reflectors nearby--such as a tall building). I know consumer units take phase measurements, but all of the ones I've seen have had rather poor measurement quality due mainly to the cheap antennas they use (survey quality GPS antennas are at least 8 inches in diameter and cost hundreds, even thousands of dollars if they use a choke ring to mitigate multipath).
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2mm, China's COMPASS and more on GLONASS (Score:5, Insightful)
A little more related to GLONASS, there's COMPASS, the global positioning system of China. It's first satellite was successfully launched last February [computing.co.uk].
Here I provided (shameless but informative plug) news on Europe's Galileo, which somehow solved their important funding problems [slashgeo.org]. As for GLONASS, Putin himself clearly stated he wants GLONASS back to full speed [blogspot.com].
Anyone avid of GPS-related news is welcomed here [slashgeo.org] (this is the GPS topic on Slashgeo, yeah, a plug, but hey, it's right on topic no? And there's no ads whatsoever
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Re:2mm, China's COMPASS and more on GLONASS (Score:4, Informative)
You can already do this with the US based GPS system using OPUS. Forgive my bad html, but here is the link:
http://www.ngs.noaa.gov/OPUS/ [noaa.gov]
You have to set up your reciever to log satilite observations over at least 2 hours, and take a reading at least every 5 minutes. Opus uses precises satilite orbital information to post process point information. The accuracy of your results depend upon how long you run your observations, and how many observations you log. I typicall run mine over 4 hours, and get an accuracy of around 4mm horizontal. Opus is a great tool when you need to tie your land survey to WGS84 coordinates, or State plane coordinates.
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Re:No, it's not used for targeting.. (Score:4, Interesting)
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Re: (Score:3, Informative)
Re: (Score:3, Funny)
I don't know about that. I'd rather have a clock that said 3:15 when it was actually 3:10, than 2 clocks that said 2:20 and 1:45 when it was actually 3:10.
better article (Score:5, Informative)
They say it can theoretically cover all of Russia because only 13 of the 18 are operational. Here's an interesting quote from the article:
satellite life? (Score:2)
Actual article about GPS and it's rivels (Score:5, Informative)
Somebody please stomp out myminicity. It's seriously polluting
Aperture Science We do what we must because we can (Score:2, Funny)
Then we can all be test subjects and enjoy delicious and moist cake!
Dilemma? (Score:3)
A man with one GPS knows where he is; a man with two is never quite sure.
[Apologies to Lee Segall.]
Yeah! More GPS sat's (Score:5, Informative)
This is good news for land surveyors everywhere. Most all surveyors have switched over to GPS based equipment in the last 10 years. I have been out in the field with GPS equipment, and watched my accuracy go to hell because there were not enough satilites above the horizon. Being able to pull signals from both systems means less downtime for land surveyors, and better field accuracy.
Engaget does not have one fact correct. Topcon has been offering surveying grade GPS units that can pull signals from both the US based system, and the GLONASS system for at least 3 years.
http://www.topconpositioning.com/uploads/tx_tttopconproducts/HiPerPro_Broch_REVB.pdf [topconpositioning.com]
BTW, if you are wondering how land surveyors get the accuracy down to 1cm for gps, it involves using two GPS recievers and a process called RTK. In RTK one reciever (the base) is placed over a known point, and equipped with a radio transmitter. This station transmitts a correction for the GPS signal to the other reciever (the rover). The results are very accurate, and our firm has pretty much stopped using conventional total station, except where vertical accuracy is an issue (gps is only good to 10cm in vertical accuracy).
Re: (Score:2)
Also, can you provide some geographic reference to where you haven't had enough satellites above the horizon?
Re: (Score:3, Informative)
I have been out in the field with GPS equipment, and watched my accuracy go to hell because there were not enough satilites above the horizon.
Maybe that was the case 10-15 years ago, but definitely not today. Not only do they have 31 out of 32 possible satellites in use, but there are even a few backup satellites up there in case something happens. On average you can expect 10+ satellites visible at any given time. Don't take my word for it though, you can easily load the current almanac [uscg.gov] into a viewer program and see for yourself.
If you're still having problems with your GPS receiver, maybe it's time to get a new one..
Re: (Score:3, Interesting)
Re:Yeah! More GPS sat's (Score:4, Informative)
Parent
Why alternatives? (Score:3, Insightful)
Re:Why alternatives? (Score:5, Interesting)
Parent
Re: (Score:3, Funny)
I admit Leica has been behind the ball on adopting GLONASS, but I still like their post processing better. Multiple observations on a single point work out much better in Leica.
Dupe (of a sort) (Score:3, Interesting)
No no. You've got it backward! (Score:3, Funny)
In Soviet Russia, You give GPS directions!
Re:I found this interesting (Score:4, Informative)
So far, I've counted 3 myminicity accounts spamming slashdot:
spx2.myminicity.com
fohootville.myminicity.com
budgieton.myminicity.com
Motion Twin is the company that makes the product, email them and complain about the account here:
contact@motion-twin.com
Also, if slashdot would follow redirects on links and display the final destination domain after the link, that would be great.
Parent
Re: (Score:2)
Re: (Score:2)
Re: (Score:3, Interesting)
Re:Poor research by /. No suprises then. (Score:5, Informative)
by ground based infrastructure you mean egnos/waas? only the most modern gps receivers support differential gps and most times it doesn't work anyway.
it is actually better to have glonass online at last - it makes dual mode navstar/glonass receivers a reality. such dual mode receivers would probably be much more exact.
Parent
Re: (Score:2, Interesting)
by ground based infrastructure you mean egnos/waas? only the most modern gps receivers support differential gps ...
Sounds kind of troll-ish, but I'll bite... Wouldn't want your misinformation to be spread around Slashdot.
If by 'only the most modern', you mean 'the majority of the GPS receivers made in the last 10 years', then yes. WAAS wasn't around back in the days of GPS infancy, but most new receivers have it, and yes
... and most times it doesn't work anyway
Now that's just wrong. The FAA (Federal Aviation Administration) designed WAAS to allow aircraft to shoot approaches into airports. I help design aircraft GPS systems for a living, so I can tell
Re: (Score:3, Interesting)
The biggest issue with WAAS being that those of us in the central area of North America may have both satellites very near the horizon. If you are on either coast one satellite is high enough above the horizon to be clear line of sight past most ground obstacles. exceptions being large nearby buildings, or mountains.
Of course, I do
Re: (Score:3, Interesting)
only the latest generation of consumer gps chipsets (sirf star III and alike) does support it. and it doesn't work well on the ground so pilots and navy are pretty much only ones who can use it.
you might not believe it, but either ones are among a minority of gps users.
Re: (Score:3, Interesting)
the most widespread consumer gps chipset is sirf star II. it doesn't support dgps. only the latest generation of consumer gps chipsets (sirf star III and alike) does support it. and it doesn't work well on the ground so pilots and navy are pretty much only ones who can use it.
Sure, I'll give you that, as long as we're clear that the the problem isn't the WAAS system itself. Whether or not consumer-grade receivers ever implement a fully-compliant receiver is anyone's guess... 2-3 meter accuracy is possible if they ever get around to it.
Re: (Score:3, Informative)
ie they can find a city like Grozny, Chechnya.
But when it came to a satellite phone kill (Chechen leader Dzokhar Dudayev), they had to ask the NSA for help.
Re: (Score:2, Troll)
Re: (Score:3, Insightful)
"In somewhat upgraded form" our spacecraft are also still flying. In fact, it is such a wonderful all-encompassing expression — "in somewhat upgraded form" — that, pretty much, everything qualifies... But thank you for granting the "technically impressive" bit. One could deduce from that, that US has beaten the
Re: (Score:2)
Because kissing Mickey's arse is more important than the oil, gas and technological trade Russia did not become a part of any stinking trade agreements when it was interested. It is now one of the few nations that are not part of these agreements and is finding its ability to use this position to its advantage very appealing.
For example it can kick all Georgian, Moldovan imports and exports to Ukraine profilactically at its whim. If it was part of these agreements it would not h
Re: (Score:3, Insightful)
Wait a minute...
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But you will still fsck up there — and everywhere else in USSR — thanks to the deliberately incorrect Soviet maps :)
Re:Given the limited number of geo-stationary spot (Score:2)
Brett
Re:Given the limited number of geo-stationary spot (Score:2)
Re: (Score:2)
Justifying defense spending (Score:4, Insightful)
Justifying defense spending is easy. Just line up your favorite talking heads on TV and have them talk about how the people who look different and talk weird really really hate freedom and want to kill all right-thinking peace-loving citizens. Have the talking heads subtly or not-so-subtly question the courage and patriotism of anybody who isn't pissing their pants over the supposedly imminent threat.
Then arrange to borrow the funding for the defense spending. This way, you can put off paying the bills until it's somebody else's problem. With any luck, your political opponent will be in office then, and you can criticize them for the economy that you screwed up. Bonus points if they try to raise taxes to pay off the debts you incurred -- or even just try to end the huge tax cuts you gave to your filthy-rich buddies. (Many of whom just happened to profit enormously from defense contracts and/or own the media corporations who practiced "balanced" journalism by not questioning your lies.)
Wheee! It's a fun game that everyone enjoys
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