GPS use for NAV when coded not in WGS84
This just in....
Doing some late night research on Wiki I found this:
I could not find any primary reference to quote, but it makes me wonder why in hell the Russians don't just use WGS-84. In any case, WGS-84 is the standard, by ICAO agreement.
GF
GLONASS uses a coordinate datum named "PZ-90" (Earth Parameters 1990 - Parametry Zemli 1990), in which the precise location of the North Pole is given as an average of its position from 1900 to 1905. This is in contrast to the GPS's coordinate datum, WGS 84, which uses the location of the North Pole in 1984. As of September 17, 2007 the PZ-90 datum has been updated to differ from WGS 84 by less than 40 cm (16 in) in any given direction.
GF
Probably, but I don't see the point. Everywhere in the RF and China has been extensively mapped and put into WGS-84 by us, so they aren't hiding anything, anymore. If they want to use different datums, just have the equipment set to change datums. We could do it in the A-10 in 1986, it's nothing dramatic.
GF
GF
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GPS v Galileo v Russian system
but it makes me wonder why in hell the Russians don't just use WGS-84.
Europe is building its own satellite navigation system called Galileo. It will consist of 30 satellites and the first should be launched in 2010, with the system operational at the end of 2013. Total cost about 4.9 bn EUR.
From NewScientist 20May 2009 : "
DON'T take your satnav for granted. Existing satellites are ageing, and replacements are behind schedule and over budget, according to a report from the US Government Accountability Office (GAO).
Satnavs and other GPS devices calculate their position by comparing time signals from at least four satellites. To keep that many within range at all times requires a fleet of at least 24. For now there are 31 operating, but 13 of them are more than four years past their design lifetime.
The first replacement "block IIF" satellites are not due to launch till November, three years behind schedule, and the GAO predicts a 20 per cent chance that the fleet will drop below 24 at times in 2011 and 2012. That wouldn't cause GPS to shut down, but its accuracy would drop unpredictably.
Plans by the US air force for the next generation of improved "block IIIA" satellites could also fall behind. The GAO calculates that if they slip by just two years, there is a 90 per cent chance that the fleet will drop below 24 in 2018."
Last edited by rudderrudderrat; 3rd Jan 2010 at 09:08.
TOD
For those of us without LIDO, can you post the complete quote or a link?
This could generate a big change in aircraft limitations.
GF
For those of us without LIDO, can you post the complete quote or a link?
This could generate a big change in aircraft limitations.
GF
Because an hydraulic system can fail and we need a back-up. Once the Earth is surveyed, how would the coordinate system fail? The satellites might not be there or fail, but lat/longs are just there.
Perhaps, the RF should just roll into the ICAO and use WGS-84, there is no advantage to holding onto a datum that is just a duplicate of it.
BTW, I quite agree that the three systems are needed and should seamlessly integrate because GPS was never intended to be used as it is now being used. And that is one of the reasons for objections to it.
GF
Perhaps, the RF should just roll into the ICAO and use WGS-84, there is no advantage to holding onto a datum that is just a duplicate of it.
BTW, I quite agree that the three systems are needed and should seamlessly integrate because GPS was never intended to be used as it is now being used. And that is one of the reasons for objections to it.
GF
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Perhaps, the RF should just roll into the ICAO and use WGS-84, there is no advantage to holding onto a datum that is just a duplicate of it.
I'm really looking forward to the day when there is just one agreed datum - but I won't be holding my breath.
Rudderrat
Technically, the ICAO is standardized on Hpa and Mbs is a UK exception. And so is inches in the US, an exception. I still call it millibars, though. Kgs is a unit of mass, while Lbs is a unit of Force. 1 kg would be the same here or on the moon, while a pound here is 1/6th of a pound on the moon.
GF
Technically, the ICAO is standardized on Hpa and Mbs is a UK exception. And so is inches in the US, an exception. I still call it millibars, though. Kgs is a unit of mass, while Lbs is a unit of Force. 1 kg would be the same here or on the moon, while a pound here is 1/6th of a pound on the moon.
GF
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.. some of us still think in slugs and poundals, not to mention forces due to the flickering of a newt's whiskers, ergs, and so forth.
If disciplines ever end up with uniform units there will be no remaining mysteries nor any useful things to pontificate over a beer at the bar on Saturday night for old chaps.
Younger chaps can always find merit in the appearance of the young lady at the other end of the bar, of course ...
If disciplines ever end up with uniform units there will be no remaining mysteries nor any useful things to pontificate over a beer at the bar on Saturday night for old chaps.
Younger chaps can always find merit in the appearance of the young lady at the other end of the bar, of course ...
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While I can't be sure about the Russian Federation standard datum, I know that the Papua New Guinea WGS-84 survey was locally referred to as PNG-94 (the year in which the survey was initiated). Perhaps the RF did something similar for local consumption while, at the same time, complying with the ICAO standard of WGS-84.
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Only because it's Newton's birthday today :
Hi GF,
A mass of one pound will still have the same mass wherever it is (earth, moon, in orbit in the space station etc.) However it will only weigh 1/6 of it's weight on the moon as compared to earth, (Likewise 1 kg will only weigh 1/6 on the moon). Both will be weightless in the space station.
1 kg would be the same here or on the moon, while a pound here is 1/6th of a pound on the moon.
Last edited by rudderrudderrat; 4th Jan 2010 at 15:00. Reason: spelling
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GF,
The satellites might not be there or fail, but lat/longs are just there.
We will roll in but Is WGS84 ICAO standart or recommedation? I think the last one.
I asked about hydraulic meaning not system redundancy. It is something more important, something with world monopoly. When monopolist after some time starts thinking that his democracy is the most democratic in the world, his english is englisher than in England he tend to think that oil in another country is their oil because this part of the world is just coordinated in WGS84.
Don't take these words seriously - we are not soviet militarists anymore
, I just want to show that alternatives are very important sometimes despite he fact their are stupid.
The satellites might not be there or fail, but lat/longs are just there.
We will roll in but Is WGS84 ICAO standart or recommedation? I think the last one.
I asked about hydraulic meaning not system redundancy. It is something more important, something with world monopoly. When monopolist after some time starts thinking that his democracy is the most democratic in the world, his english is englisher than in England he tend to think that oil in another country is their oil because this part of the world is just coordinated in WGS84.
Don't take these words seriously - we are not soviet militarists anymore
, I just want to show that alternatives are very important sometimes despite he fact their are stupid.
Thanks very much, TOD
Boroda
But, WGS-84 is not a monopoly, it is not even a tradable good, it just IS. ICAO cannot dictate anything, but as a Standard and Recommended Practice, the ICAO said aviation will use WGS-84. Hell, we could use Argentine 1925, just as long as everyone's equipment is compatible and we are all using the same thing.
Considering PZ-90 has been modified to nearly conform with WGS-84, the only alternative we are talking about here is a name. Let's just call it "Fred's Lat/Long System".
GF
Boroda
But, WGS-84 is not a monopoly, it is not even a tradable good, it just IS. ICAO cannot dictate anything, but as a Standard and Recommended Practice, the ICAO said aviation will use WGS-84. Hell, we could use Argentine 1925, just as long as everyone's equipment is compatible and we are all using the same thing.
Considering PZ-90 has been modified to nearly conform with WGS-84, the only alternative we are talking about here is a name. Let's just call it "Fred's Lat/Long System".
GF
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Borda,
ICAO specifies the World Geodetic System 1984 (WGS-84) - or equivalent - as the geodetic reference datum Standard for air navigation latitude/longitude coordinates
ICAO specifies the World Geodetic System 1984 (WGS-84) - or equivalent - as the geodetic reference datum Standard for air navigation latitude/longitude coordinates