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New Mexico Is Stretching, GPS Reveals

Soulskill posted more than 2 years ago | from the too-many-tacos dept.

Earth 117

Velcroman1 writes "New Mexico's borders are gradually gaining girth, according to the Albuquerque Journal. It's not much, and it's not happening very fast — the state is getting about an inch wider every 40 years — but the state is unquestionably expanding, according to University of Colorado geophysicist Henry Berglund and his colleagues. Using a collection of 25 extra-precise GPS receivers planted across New Mexico and Colorado, Berglund determined that the cities of Albuquerque and Santa Fe are creeping away from each other. The rate of change seems ever so slow to the untrained ear, described as approximately 1.2 'nanostrains' per year."

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Black Mesa (5, Funny)

bonch (38532) | more than 2 years ago | (#38733376)

But the effect in continental interiors -- on states not near the edge of those plates -- was a new one, the scientists said. Whether an upwelling in the gooey mantle that lies beneath the crust or a sag in the plates themselves, what exactly drives the growth remains a mystery.

Probably those experiments over at Black Mesa. By the way, the portrayal of New Mexico in Half-Life always amused me, with the cartoonish Looney Tunes cliffs and plateaus. With the exception of the northern area of the state, it's mostly just weeds as far as the eye can see [imgur.com] , littered with the occasional beer can. We have good Mexican food, though.

Re:Black Mesa (1)

Nidi62 (1525137) | more than 2 years ago | (#38733414)

Well, with a name like Black Mesa, it wouldn't make sense to have a flat plain as far as the eye can see. Gotta keep the game believable, you know.

Re:Black Mesa (2)

bonch (38532) | more than 2 years ago | (#38733446)

There actually is a Black Mesa, New Mexico [imgur.com] , though I don't know if the in-game location has any relation (I imagine there are probably several Black Mesas in the deserts of America.

Re:Black Mesa (1)

Megahard (1053072) | more than 2 years ago | (#38734098)

A topo map search finds 20 places in Arizona named Black Mesa.

Re:Black Mesa (0)

Anonymous Coward | more than 2 years ago | (#38736880)

It's not that far from Los Alamos as I recall.

Re:Black Mesa (3, Insightful)

PRMan (959735) | more than 2 years ago | (#38733736)

Actually, I recently drove through New Mexico and was surprised by the green fields, grazing animals and tons of nice-looking farms/ranches along a long stretch of road. It was not what Looney Tunes said it would be (that was Arizona).

Re:Black Mesa (1)

ThorGod (456163) | more than 2 years ago | (#38734382)

Actually, I recently drove through New Mexico and was surprised by the green fields, grazing animals and tons of nice-looking farms/ranches along a long stretch of road. It was not what Looney Tunes said it would be (that was Arizona).

Actually, there's a good amount of agriculture in NM, at least as far south as San Antonio, NM. Since I've moved away, that's one of the top things I miss. Az and Nv both have places they live up to the baren stereotype better.

Bugs Bunney was a trickster.... (5, Funny)

rts008 (812749) | more than 2 years ago | (#38736412)

You took a wrong turn in Albuquerque....

Re:Bugs Bunney was a trickster.... (1)

Ihmhi (1206036) | more than 2 years ago | (#38738396)

Shoulda never taken that left!

(Sir, I bow to you!)

Re:Black Mesa (1)

jbeaupre (752124) | more than 2 years ago | (#38733856)

You must be in the eastern part. I've live in 5 counties, all of them had mesas, mountains, forests, and badlands of one sort or another. Multiple mountain ranges: Gila, Black, Organ, Manzano, Sandia, Sangre di Cristo, Flores, Mt. Taylor, etc. The only thing close to that picture west of the Pecos is between Las Cruces and Deming (but that area doesn't even have the weeds).

There's a reason so many Sci Fi movies are shot in NM these days: Most of the state looks unusual. It's funny watching Breaking Bad carefully frame shots to avoid showing mountains and mesas.

Re:Black Mesa (1)

gestalt_n_pepper (991155) | more than 2 years ago | (#38733960)

A bit further between Deming and Silver City, there are farms, cows and even a herd of antelope near Bayard. No word on whether they were playing or not. Stay tuned. Towards Lordsburg.... not so much. Of anything.

Re:Black Mesa (1)

Endo13 (1000782) | more than 2 years ago | (#38734952)

Damn, seeing these posts about that part of the state makes me miss it. Lived in Mimbres Valley 20 years ago when I was a kid. Silver City was where we did our shopping.

Re:Black Mesa (2)

mjwx (966435) | more than 2 years ago | (#38735548)

Probably those experiments over at Black Mesa. By the way, the portrayal of New Mexico in Half-Life always amused me, with the cartoonish Looney Tunes cliffs and plateaus. With the exception of the northern area of the state, it's mostly just weeds as far as the eye can see [imgur.com] , littered with the occasional beer can. We have good Mexican food, though.

Well, if you were building a secret lab to run probably illegal experiments into inter-dimensional travel with the potential to bring vicious invaders to earth, which part of New Mexico would you pick.

One man's weeds, another man's nature res. (1)

fantomas (94850) | more than 2 years ago | (#38735676)

One man's weeds, another man's area of natural beauty..... [nature.org] .

Re:Black Mesa (1)

niktemadur (793971) | more than 2 years ago | (#38737086)

The portrayal of New Mexico with the cartoonish Looney Tunes cliffs and plateaus.

Let's not forget George Herriman's seminal comic strip Krazy Kat, source of my sig.
Kokonino Kounty's mesas and surrealistic landscapes predate The Road Runner by more than a quarter century.

Finally, I can't resist taking a jab at that headline:
New Mexico Is Yawning, Sonar Reveals.

Re:#SOPA (1)

b4dc0d3r (1268512) | more than 2 years ago | (#38738646)

Good job, idiot. You linked to a page with words on it. You should try the preview button some time, make sure your links actually work before posting.

-Average Joe

Organized trolling campaign on Slashdot (-1, Offtopic)

Anonymous Coward | more than 2 years ago | (#38733392)

GreatBunzinni [slashdot.org] has been posting anonymous accusations [slashdot.org] listing a whole bunch of Slashdot accounts as being part of a marketing campaign for Microsoft, without any evidence. GreatBunzinni has accidentally outed himself [slashdot.org] as this anonymous poster. Half the accounts he attacks don't even post pro-Microsoft rhetoric. The one thing they appear to have in common is that they have been critical of Google in the past. GreatBunzinni has been using multiple accounts to post these "shill" accusations, such as Galestar [slashdot.org] , NicknameOne [slashdot.org] , and flurp [slashdot.org] .

That's not the problem. The problem is that moderators gave him +5 Informative and are now modding down the accused, even for legitimate posts. Metamoderation is supposed to address this by filtering out the bad moderators, but clearly it's not working.

This "shill" crap that has been flying around lately has to stop. It's restricting a variety of viewpoints from participating on the site and creating an echo chamber.

Slashdot has really gone downhill recently... (-1)

Anonymous Coward | more than 2 years ago | (#38733408)

Fox News? Really?

Re:Slashdot has really gone downhill recently... (0)

Anonymous Coward | more than 2 years ago | (#38733472)

You should really open your eyes a bit and grow up.

Re:Slashdot has really gone downhill recently... (2)

jjjhs (2009156) | more than 2 years ago | (#38733580)

It's obviously Fox's liberal agenda to separate the poor and their filth from the rich as physically far as possible.

Re:Slashdot has really gone downhill recently... (1)

Anonymous Coward | more than 2 years ago | (#38733882)

Poor Mexico, so far from God and so close to the United States!

Re:Slashdot has really gone downhill recently... (0)

Anonymous Coward | more than 2 years ago | (#38734870)

WTF are you talking about?

Re:Slashdot has really gone downhill recently... (0)

Anonymous Coward | more than 2 years ago | (#38735040)

/s

Re:Slashdot has really gone downhill recently... (0)

Anonymous Coward | more than 2 years ago | (#38736586)

Fox's liberal agenda

Now there are three words you don't see often. :P

There go my plans (5, Funny)

rbowen (112459) | more than 2 years ago | (#38733426)

So much for driving to California next summer. It'll be farther away by then.

Re:There go my plans (0)

Anonymous Coward | more than 2 years ago | (#38733464)

Why drive tomorrow what could be closer today?

Re:There go my plans (5, Interesting)

R3d M3rcury (871886) | more than 2 years ago | (#38733926)

Perhaps I'm taking this too literally...

I'm not sure New Mexico can get any wider--it's borders are set along latitude and longitude lines. So it's more likely that Albuquerque will eventually end up in Arizona and Santa Fe will end up in Texas.

Re:There go my plans (4, Informative)

Anonymous Coward | more than 2 years ago | (#38734420)

I'm not sure New Mexico can get any wider--it's borders are set along latitude and longitude lines.

It's borders are not defined by the latitude and longitude lines, but by the markers set by the surveying team which attempted to follow the latitudes and longitudes. In pretty much every country, certainly all regions of North America, boundaries that were intended to follow specific latitudes or longitudes don't change as our ability to more accurately define these imaginary lines on the globe. Typically the act in Canada or the U.S. that defines the national, state/province or county borders as following specific lat. or long. lines also includes the phrase "as defined by" and the specific survey mission that defined the border using the technology then available.

So every border that is popularly defined by a latitude or longitude is rarely accurate as the technology was often quite crude compared to what we can do today.
Therefore, yes New Mexico can and is getting wider and Albuquerque and Santa Fe are going to remain part of N.M. as long as some kind of hispanic revolution doesn't occur. ;-)

Re:There go my plans (0)

Anonymous Coward | more than 2 years ago | (#38739004)

They can keep Santa Fe, its full of politicians and hippies.

Re:There go my plans (0)

Anonymous Coward | more than 2 years ago | (#38739740)

With the amount of Texans in Santa Fe for ski season, this may have already happened

but what about jersey? (0)

Anonymous Coward | more than 2 years ago | (#38733432)

It's already bordering six other states, including Hawaii! When will it reach South Park?

The Obesity Epidemic (5, Funny)

Anonymous Coward | more than 2 years ago | (#38733454)

...is so bad in the United States now, even the GROUND is getting fatter.

Re:The Obesity Epidemic (3, Informative)

rts008 (812749) | more than 2 years ago | (#38736444)

Why do you hate America?
High Fructose Corn Syrup!!! Where's the Beef? Supersize me!
Wahoooo!

I don't know (1)

ticker47 (954580) | more than 2 years ago | (#38733458)

New Mexico was where LightSquared was testing their LTE system...

Nevada too? (1)

jasno (124830) | more than 2 years ago | (#38733470)

I believe the same thing is happening to Nevada. It's what causes the "horst and graben" faulting and the north-south mountain chains.

Re:Nevada too? (1)

MichaelSmith (789609) | more than 2 years ago | (#38733512)

Stretch marks?

Re:Nevada too? (2)

c0lo (1497653) | more than 2 years ago | (#38733962)

Stretch marks?

The correct term is "nanostrain marks".

Re:Nevada too? (1)

yurtinus (1590157) | more than 2 years ago | (#38739834)

There's nothing "nanostrain" about the great basin...

Not News (5, Funny)

sunderland56 (621843) | more than 2 years ago | (#38733480)

Yeah, yeah, we know - America is getting fatter.

Re:Not News (2)

MichaelSmith (789609) | more than 2 years ago | (#38733530)

And then there is the expansion of the universe to consider. Whats's the red shift of Mexico City right now?

Re:Not News (2)

L4t3r4lu5 (1216702) | more than 2 years ago | (#38736690)

The leading political party is liberal, so I'd say it's more of a blue shift. This very handily brings us back to the Half Life comments at the top.

Apparently a side effect of resonance cascades is pre-destination and determinism.

Re:Not News (2)

R3d M3rcury (871886) | more than 2 years ago | (#38733714)

Yeah, but it's not that bad--1 inch every 40 years. Personally, I added about an inch in the past year.

Re:Not News (1)

rts008 (812749) | more than 2 years ago | (#38736482)

Personally, I added about an inch in the past year.

Piker!
I can claim 3cm's this year, n00b!

*The above was to be taken in jest.*

Spoil (1)

slowLearner (2498468) | more than 2 years ago | (#38733562)

They have to put the spoil from all those tunnels someplace!

Quoting Wash from Firefly (1)

Gothmolly (148874) | more than 2 years ago | (#38733564)

Wait, are we caring?

because of (-1)

Anonymous Coward | more than 2 years ago | (#38733588)

all the beaners?

GPS Accuracy (3, Interesting)

Proudrooster (580120) | more than 2 years ago | (#38733628)

Fellow Slashdotters... this is a little off topic, but is there any way to get accuracy out of GPS? I can barely get plus/minus 12 feet of accuracy out of my GPS in the best conditions. How are they able to determine sub-inch accuracy? This sounds impossible, even with "25 extra-precise GPS receivers" as stated in the article. I just don't believe it is possible to measure to this level of accuracy with GPS. Someone please prove me wrong and school me how to build one with this accuracy for my autonomous lawn bot :)

Re:GPS Accuracy (4, Interesting)

BitterOak (537666) | more than 2 years ago | (#38733668)

They probably use techniques like differential GPS [wikipedia.org] to increase their accuracy.

Re:GPS Accuracy (0)

Anonymous Coward | more than 2 years ago | (#38733792)

Differential GPS uses ground-based fixed points of reference. How does that help when what you're trying to measure is changes in the ground itself?

Re:GPS Accuracy (1)

sjames (1099) | more than 2 years ago | (#38734500)

If you have 2 ground based points and the ground is moving, you can get very accurate relative measurements.

Re:GPS Accuracy (5, Informative)

NatasRevol (731260) | more than 2 years ago | (#38734056)

They also use very large antennas (relative to commercial/handheld units).

The antenna's Henry is using are about 20" across and have some shielding to protect from signals reflected from the ground.

See:
http://facility.unavco.org/kb/questions/325/5%7B47%7D8%22+Stainless+Steel+All-thread+Mast+Overview [unavco.org]

I know, because I work there.

Re:GPS Accuracy (1)

Formalin (1945560) | more than 2 years ago | (#38733722)

Good question, I came to post this too. Mod parent inquisitive.

AFAIK the fed can enable the higher-accuracy bit on GPS, but I don't think it is anywhere near 1/40th of an inch accurate, like TFS impies.

Re:GPS Accuracy (2)

tomhath (637240) | more than 2 years ago | (#38733760)

A couple of years ago some coal miners were trapped underground in Pennsylvania. They brought in someone with super expensive GPS equipment to locate where to drill the rescue hole. As I recall he claimed he could fix the position within a few centimeters. Anyway, they drilled where he said and hit the chamber where the men were located, so he was either very good or very lucky. But don't expect your phone or other (non-special-government licensed) consumer device to be much better than a few meters.

Re:GPS Accuracy (3, Informative)

Shavano (2541114) | more than 2 years ago | (#38733786)

You use 2- frequency GPS receivers that are inherently less noisy and more accurate than the cheap ones everybody uses for coarse navigation. Then you average the position data over long times.

The longer you average, the lower the uncertainty in the position.

Re:GPS Accuracy (1)

Shavano (2541114) | more than 2 years ago | (#38733930)

There's also the point that this inherently a differential question. They use simultaneous data from two receivers that see the same satellites at the same time to solve for the difference in position rather than the absolute position of each receiver. You can do this for each pair in their set of 25 receivers or for any subset.

Fancy math: cool answers.

Re:GPS Accuracy (2)

weweedmaniii (1869418) | more than 2 years ago | (#38733808)

If they use military-grade GPS systems they can get sub-inch accuracy. All everyone else can get a lot less accurate. One of the reasons China is putting up their own satellite constellation for the own GPS-type system, so they can achieve the same accuracy our system has. I suspect they either can't crack the coding to use the more accurate system, or more likely they have cracked it and reverse engineered it.

Re:GPS Accuracy (0)

Anonymous Coward | more than 2 years ago | (#38734202)

http://www.spacedaily.com/news/gps-00d.html

I'm not sure why people keep repeating this. Its not true, the civilian GPS is the same accuracy as the military since the Clinton administration.

Re:GPS Accuracy (2, Informative)

Anonymous Coward | more than 2 years ago | (#38734336)

http://www.spacedaily.com/news/gps-00d.html

I'm not sure why people keep repeating this. Its not true, the civilian GPS is the same accuracy as the military since the Clinton administration.

They keep repeating it because it is true. Military GPS uses different signals which still result in better accuracy, even with the removal of selective availability.

From the US government's GPS page [gps.gov] (emphasis added):

Is Military GPS More Accurate Than Civilian GPS?

The accuracy of the GPS signal in space is actually the same for both the civilian GPS service (SPS) and the military GPS service (PPS). However, SPS broadcasts on only one frequency, while PPS uses two. This means military users can perform ionospheric correction, a technique that reduces radio degradation caused by the Earth's atmosphere. With less degradation, PPS provides better accuracy than the basic SPS.

Re:GPS Accuracy (2)

imidan (559239) | more than 2 years ago | (#38733812)

Stationary GPS is a little bit different. The receiver is planted in a location whose coordinates can be very carefully determined via more traditional survey methods. Combine this with some other technologies, and you can get very precise and accurate results. For example, one of the factors that degrades the accuracy of GPS is atmospheric effects. With a network of carefully surveyed stationary GPS units, we can correct for atmospheric effects by seeing how 'off' the various units are compared to normal, and to each other. There are other sources of error, but the point is that GPS error can be greatly reduced when you already know where you are.

Now, in this case, the 'stationary' GPS units are actually moving at a very slow rate. With the error corrections described above, once all the other errors are accounted for, what remains is error due to actual movement of the GPS. I can't see the full text of the paper, but probably what they have is a statistical model that says the GPS units are moving by a certain amount each year, and a confidence level, and all of that.

So, to your last point: if you want to improve the GPS accuracy of your lawn bot, you need only to install a stationary GPS receiver on your house, survey its location very carefully, and attach a transmitter to turn it into a 'GPS base station' that your robot's GPS will use as a local reference to improve its GPS fix. (You can buy a GPS base station from someone like Trimble; they're often used for construction and the like.)

Re:GPS Accuracy (3, Interesting)

dido (9125) | more than 2 years ago | (#38733848)

Differential GPS [wikipedia.org] gets accuracy to up to 10 cm, which is just above 4 inches I think. It seems that it is possible to obtain even sub-millimeter accuracy [nxtbook.com] from GPS, although I gather the techniques used aren't real-time, and as such unsuitable for mobile robotics. :( They work well enough for surveying though.

Re:GPS Accuracy (3, Informative)

maroberts (15852) | more than 2 years ago | (#38736248)

I was working for a company on differential GPS back in 1992 and we were obtaining precision of less than a centimetre for differential GPS even then, real time. Admittedly "real time" was only about 1 update every 5 seconds or so but that was good enough for surveying purposes. Also we were generating an atomic reference clock using GPS to correct the receiver oscillator. If the resulting time signal was good enough for radio astronomy at Jodrell Bank, I presume it was good enough for anyone.... We were using 68000 processors (later 68020) backed up by custom ASICs; Clock speeds and power have come a long way since then.

Re:GPS Accuracy (1)

Muad'Dave (255648) | more than 2 years ago | (#38739412)

We were using 68000 processors...

Wow - you really did imagine a Beowulf cluster of ... oh, you mean Motorola 68000 (tm) processors. Drat!

Re:GPS Accuracy (1)

tokul (682258) | more than 2 years ago | (#38739368)

to 10 cm, which is just above 4 inches I think

2.54*4 = 10.16 cm
below 4 inches, if your below and above don't reffer to accuracy.

Re:GPS Accuracy (2)

FrankSchwab (675585) | more than 2 years ago | (#38733866)

Differential GPS, as BitterOak said, as well as some exotic techniques of receiving the GPS signal, as well as certain signal processing approaches - you're measuring distances over a year; there's a lot of processing gain if you simply take a million readings and average them!

There's a good chart here http://www.geoplane.com/gpsneeds.html [geoplane.com] showing the cost curve as accuracy goes up.

Re:GPS Accuracy (5, Informative)

oneblokeinoz (2520668) | more than 2 years ago | (#38733886)

The key thing is that this level of accuracy is not achieved in realtime.

The receivers would be recording more than the information contained in the GPS messages, they would be recording phase and signal strength data for all the satellites in the visible constellation.

Sophisticated post processing software would combine this information across multiple receivers, along with published satellite ephemeris data, to produce an accurate position solution.

Realtime positions cannot be that accurate due to affects like ionospheric refraction etc.

I used to work with a mobile system that recorded the GPS data along with inertial information (at 200Hz) that in realtime gave a solution that was usually accurate to within 30cm, and got to better than 10cm when combined with static ground station data in the post-processing step.

There are systems used in agriculture that are very accurate (10cm-ish) that use differential-GPS in realtime. The trick is your mobile unit has to be in constant communication with the differential ground station. Works ok for tractors, not so well for an aircraft 200-300km away. For differential-GPS to work well both units need to see the same satellites.

Re:GPS Accuracy (1)

Proudrooster (580120) | more than 2 years ago | (#38733950)

Thank you, I wish I had mod points... This clears up some questions I had about GPS. I have been trying to use a fixed point (known location) as a starting reference, but I could never come up with an %-error calculation for the Long/Lat as I moved away from that position. Additionally both the %-error and position and it would drift each day and even averaging the data over time never got close to plus/minus 10 feet. I have since switched to gyros, magnometers and accelerometers but they have their issues and they drift over time. It is such a maddening challenge to figure out your exact location to sub-inch accuracy.

Thanks for your post!

Re:GPS Accuracy (1)

oneblokeinoz (2520668) | more than 2 years ago | (#38734072)

I was living in the US at the time when "selective availability" was turned off. This was the deliberate manipulation of the non-military GPS signals to make the position solution less accurate.

I set my laptop up to record and plot my position on the night it was disabled, using a Delorme GPS. The next morning it showed a wide green wandering star-ish shaped track roughly around my house in the early part of the recording, and just a steady green blob for the later hours. I wish I had bothered to be more careful and save the track for historical purposes, but from memory the diameter of the enclosing circle of positions was over 50 meters when SA was on, and only a couple of metres after it had been turned off.

Re:GPS Accuracy (2)

tibit (1762298) | more than 2 years ago | (#38734408)

You should have perhaps asked someone who knows a bit about it, since those are all problems with known solutions. A GPS receiver that you can buy for less than USD $1k won't give you anwyhere near the accuracy you can pull out of the signal in realtime without using any differential techniques at all. For about $15-$20k in gear (multifrequency receivers with phase processing and ionospheric correction, large antenna, etc) you can get a couple mm of error in real time. Add to that another "nearby" receiver for a differential setup and your relative error can drop to well under a millimeter. Be prepared to spend good money for that. A good car's worth.

Re:GPS Accuracy (1)

adolf (21054) | more than 2 years ago | (#38735314)

Be prepared to spend good money for that. A good car's worth.

What's a "good car" worth? Are we talking H1 Hummer, Pagani Zonda, or a Kia Whatever?

They're all "good cars," in that they're all solid and reliable, and are also optimized for their purpose.

So please forget the car analogy, and use a value that people can actually relate to. (Dollars would be adequate.)

Re:GPS Accuracy (2)

ThePeices (635180) | more than 2 years ago | (#38736994)

Hummer? Kia?

He said a "good" car.

Re:GPS Accuracy (0)

Anonymous Coward | more than 2 years ago | (#38737880)

The Hummer is a good car for those battlefield tailgate parties. For anything else... not so much.

Re:GPS Accuracy (0)

Anonymous Coward | more than 2 years ago | (#38738124)

He did. 15-20k in gear plus another receiver - so another 15-20k.

30-40k.

It's math. Do it.

Re:GPS Accuracy (1)

mini me (132455) | more than 2 years ago | (#38733904)

The RTK receivers used to power much larger lawn bots (i.e. farm equipment) claim 1-2cm accuracy. They are quite expensive and require correction data from an external source; either a base station or a subscription with someone who will provide the base station date, typically over IP. With a decent budget, it's definitely possible though.

Re:GPS Accuracy (0)

Anonymous Coward | more than 2 years ago | (#38734224)

Down to 5mm with survey grade GNSS gear. (Which can use far more frequencies/satelites/systems than the "normal" L1 receivers you and I typically use)

http://water.usgs.gov/osw/gps/index.html

Re:GPS Accuracy (1)

bemymonkey (1244086) | more than 2 years ago | (#38735126)

Isn't consumer GPS artificially liimited in accuracy? I thought the military and government versions were much, much more accurate...

Re:GPS Accuracy (1)

Wingman 5 (551897) | more than 2 years ago | (#38735372)

Isn't consumer GPS artificially liimited in accuracy?

Not artificially, economically. It costs a LOT more to get real-time sub 1m accuracy without post-processing. For what you are using the gps for (navigating a turn on the street 90% of the time) 1-5m accuracy works fine. You can buy high end equipment (we are taking more than $1K) and get realtime data in the 1 inch range. For 10-20K you can get to the millimeter range.

Which would you buy to use in your car, the $50 GPS, or the $900 gps with the only additional feature it has is if you go to the menu that actually displays your lat/long you get a few more decimal points?

Re:GPS Accuracy (0)

Anonymous Coward | more than 2 years ago | (#38736758)

Being a Register Land Surveyor, I would suggest that most of the misundertstandings about GPS could be addressed by just talking with one of the New Mexico Professional Surveyors who will gladly explain how Survey Grade GPS works and how they can provide you with sub-millimeter accurate locations. Since they get paid to locate things, they already own equipment that is many time more accurate than recreational grade GPS equipment. And they are familar with computational techniques to ensure that all the post-processing to produce that level of accuracy is done properly.

Do yourself a favor, call one of those folks and you will find, its not all that expensive.

Re:GPS Accuracy (1)

spectrokid (660550) | more than 2 years ago | (#38735794)

When you drive around, you get to see a couple of sats for a few seconds, and then your position has changed again. If the receiver knows it is bolted to the floor, it can track satellites for hours and calculate very nice averages.

Re:GPS Accuracy (0)

Anonymous Coward | more than 2 years ago | (#38738042)

for your lawn bot, there are better ways than GPS: optical benchmarks and image processing springs to mind.
For GPS, there's a whole raft of error sources in the sub-meter range, and high precision is either beating them down one at a time, or doing a differential measurement where they cancel.
First off, you need to get a good antenna.. A choke ring, specifically. The canonical one is called a Dorne Margolin (D-M) but there's lots of flavors, including one made from nesting cake pans. That helps suppress multipath from the ground under your antenna.

Next, you might want a 2 frequency receiver (although with differential techniques or post processing, you can back out the ionosphere other ways).

There's also a big difference between high accuracy differential and post processed. Both can give you accuracies on the order of millimeters. In real time (usually called Real Time Kinematic RTK) it's a differential technique, where you compare your observables against those at well defined points. Accuracy of a few ppm of the distance to the reference + a few mm is typical. These days, there are networks of high accuracy references you can use, all you need is a low speed data connection so your receiver can ingest the reference data and add it to its solution.

Or, you can collect your data as raw observables (code phase, etc.) in RINEX form, and use the free GIPSY processing to reduce it to geodetic quality measurements, some days later.

Re:GPS Accuracy (0)

Anonymous Coward | more than 2 years ago | (#38739830)

Use DGPS, involves a fixed base station and software for post processing correction.

I knew it! (0)

Anonymous Coward | more than 2 years ago | (#38733716)

New Mexico is so much better than Old Mexico!

And Leon's getting LARGER! (1)

Anonymous Coward | more than 2 years ago | (#38733754)

Airplane quote for the win!

This is news? (4, Insightful)

QuasiEvil (74356) | more than 2 years ago | (#38733764)

Seriously? The entire Rio Grande Valley - which pretty much covers a north-south line right down the middle of the state - is a rift valley. The continent has been splitting and spreading here for millions of years. It's an interesting measurement, to be sure, and it's nice to have confirmation, but it shouldn't come as much of a surprise.

Expanding? (0)

mapinguari (110030) | more than 2 years ago | (#38734032)

the state is unquestionably expanding

By definition, New Mexico lies between the 103 W and the 109 03' parallels (mostly [senate.gov] ). The only way New Mexico could be getting wider is if the earth's radius is increasing, pushing the meridians apart. Since Arizona is bounded on the west by primarily by rivers, maybe it's the one getting wider (or Arkansas!)

Re:Expanding? (1)

mapinguari (110030) | more than 2 years ago | (#38734606)

And by parallels, of course, I mean meridians.
What is it with these 503 errors?

You F4il It (-1)

Anonymous Coward | more than 2 years ago | (#38734060)

Dis3ussion I'm [goat.cx]

Unit conversions (1)

NotPeteMcCabe (833508) | more than 2 years ago | (#38734182)

So is a "nanostrain" equal to 1/40th of an inch? That seems too big for the nano prefix.

Re:Unit conversions (2)

tibit (1762298) | more than 2 years ago | (#38734390)

Nanostrain is a unitless unit. It means 10^(-9) in/in -- inches per inch. It's a relative measure of deformation, it always needs to be a applied to a length to give length. Just to look at orders of magnitude: 10 nanostrains over 100 miles = 10^(-6) mile = 0.6 in.

Re:Unit conversions (2)

mrchaotica (681592) | more than 2 years ago | (#38734432)

"Strain" is expressed as length divided by length (e.g. in/in). In other words, it's a dimensionless ratio. Here's how we calculate it for this situation:

The length (actually width) of New Mexico is about 343 miles, which is 21,732,480 inches:

L = 2.1*10^7 inch

In a year it stretches 1/40 of an inch (on average):

dL = 2.5*10^-2 inch

Therefore the strain, dL/L is:

dL/L = 2.5*10^-2 inch / 2.1*10^7 inch = 1.2*10^-9

Voila: the inches cancel and you get 1.2 dimensionless "nanostrains."

Re:Unit conversions (1)

mrchaotica (681592) | more than 2 years ago | (#38734504)

By the way, I ignored it by considering only a single year, but what I really calculated was the average strain rate, with units 1 / year (i.e., the answer is really 1.2*10^-9 year^-1). Weird, eh?

Particularly in Taos. (0)

Anonymous Coward | more than 2 years ago | (#38734190)

Hey, I'll be here all night. Try the vegetarian roast beef.

The Big Squeeze (0)

Anonymous Coward | more than 2 years ago | (#38734210)

Poor Arizona and Texas!

repulsive gravity (1)

shadowofwind (1209890) | more than 2 years ago | (#38734316)

The earth is trying to get away
From the New Agers in Santa Fe

"To the untrained EAR" (1)

vikingpower (768921) | more than 2 years ago | (#38734858)

? Huh ?

Gov't relocation program (half joking) (1)

jensend (71114) | more than 2 years ago | (#38734992)

Louisiana is losing ground fast. Some parishes will be almost entirely water pretty soon; the basic problem is that the way we're artificially keeping the Mississippi's course stable is sending all the silt off the continental shelf when it should be helping to reinforce the delta.

Maybe to mitigate the inevitable cost of cleaning that state up the next time a hurricane blows through we should give strong incentives for people to move to NM where the ground is growing rather than getting eroded into the ocean.

Somebody tell the neutrinos... (0)

Anonymous Coward | more than 2 years ago | (#38735602)

Somebody better tell the neutrinos that New Mexico is getting larger, or they'll try exceeding lightspeed there to get across it in time.

So... (1)

cgomezr (1074699) | more than 2 years ago | (#38736576)

...what about Brooklyn [youtube.com] , then?

The worst possible outcome (1)

ddd0004 (1984672) | more than 2 years ago | (#38738086)

is this will trigger another terrible Roland Emmerich disaster movie.

well known to geologists for a century (1)

peter303 (12292) | more than 2 years ago | (#38738746)

The Rio Grande rift is a classic extensional (expanding) zone. Downdrop valleys and volcanics.

all planets grow (1)

bhlowe (1803290) | more than 2 years ago | (#38739528)

An interesting theory by Neal Adams is that all planets grow...
http://www.nealadams.com/nmu.html [nealadams.com]
Perhaps the energy in the core of the planet gets converted into mass. My guess is there are lots of places on the planet that are "growing".
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