Web Concepts

Posts Tagged ‘gps’

In May 2009, North Korea detonated a clandestine nuclear test, a kilometer underground. That's worrisome for obvious reasons, and more worrisome because performing the test underground severely limits our ability to measure the size and specifics of the blast--no radioactive gas or dust was let into the air, as it usually would. But that doesn't mean there are no signs of radioactive explosions.

When a nuclear blast that large goes off underground, it sends a shockwave of disturbed air into the ionosphere. That shockwave is typically hard to measure, but these scientists may have found a way, using regular GPS. GPS, see, relies on timing more than anything else to determine location: it measures the time the signal takes to rebound from a device to the satellite, and vice versa. But disturbances in the air can change those measurements, so GPS units have sophisticated algorithms to sense and adjust to that kind of disturbance--so why not the nuclear shockwave?

The scientists performed some tests after the 2009 blast, and found that they were able to nail down the location and timing of the blast using eleven different satellites. They're optimistic that this tech could be used to supplement other ways of confirming that an illicit blast took place. They even hope that this technology might compel the U.S. to reconsider its refusal to sign the Nuclear Test Ban Treaty, which I personally am skeptical about but would certainly be great if it was true. For more info on nuclear power, check out our explainer.

[The Bulletin]

The chip, implanted in the tissue between the shoulder and elbow, sends a signal to an GPS device that the wearer carries. But Xega, the company that manufactures many of the chips, says that they can track clients even without the GPS unit, by sending radio signals directly to the implanted chip. This claim seems very unlikely to be true.

RFID researchers say that Xega’s claim that it can still find clients even if their external GPS unit has been lost is ludicrous. The technology that would allow remote tracking of RFID signals is still far off, they say. Although Xega says they have helped to rescue 178 people in the past ten years, an executive acknowledged that the implant would likely not work without the external GPS.

Mexicans have good reason to be frightened, with abductions having jumped 317 percent in the past five years. One fifth of instances have involved police officers or soldiers, which leads to a mistrust of authority figures. Xega has seen its sales increase by 40 percent in the past two years.

Other companies are selling external GPS trackers equipped with panic buttons, disguised as keychains, watches, or bracelets in the hopes of fooling kidnappers. This approach at least is not technologically impossible, although emitting a regular distress signal could quickly drain the battery of such a device.

[The Washington Post]

One of the most enduring problems of maintaining a wireless connection, whether it's 3G, 4G, or Wi-Fi, is what's called the "handoff." Individual wireless access points like a cell tower or Wi-Fi router have a limited radius within which a device can connect to them. In the case of 3G or 4G towers, the idea is to have those radii overlap, so you're never without service, but that means at some point you'll have to "hand off" from one tower as you move more fully into the radius of another.

The way that's done now is very simple: Your phone connects to the tower or access point with the strongest signal. But that simplicity can lead to some very sloppy handoffs, during which you might lose your service and drop a call. This is particularly problematic when using Wi-Fi, which has a comparatively small radius of signal. If you turn on your phone while walking, you'll connect to the strongest signal. But what if you're actually walking into the radius of another access point? You'd be better off connecting to that one first, even though it might not be the stronger of the two signals, because then you'd avoid having to disconnect from the first signal and reconnect to the second.

A group of MIT researchers have created a way to use the GPS, accelerometer, and gyroscope found in many, if not most, smartphones to make smarter connections. By sensing your movement and predicting where you're heading, it can connect to the access point that makes the most sense. In tests, a cellphone using this system switched connections about 40% less frequently than it ordinarily would, which is better for both signal and battery life.

A caveat: These tests were carried out using Wi-Fi networks, which have a very small radius and have a much more pronounced handoff than, say, a 3G network. It seems likely that a 3G version of this system would have a much smaller effect: It's much harder to predict movement across the huge radius of a 3G tower, and handoffs tend to be much smoother, anyway. But that's not to say the system wouldn't help at least a little, and it's very cool that the project uses hardware that's already found in the phones, rather than requiring some sort of hardware upgrade.

[MIT]

Asthma attacks can happen anywhere, but the causes of these attacks can be hard to pin down because patients don’t always report, or even remember, every time they pop their inhaler out for some respiratory relief. Dr. David Van Sickle’s Spiroscout inhaler aims to change this. Suck on the Spiroscout and it logs the time and position, sending it to a central computer for analysis.

That analysis benefits asthma sufferers on two levels. Individually, it allows participating patients and their doctors to analyze their inhaler use, shedding light on patterns that may develop in inhaler usage or indicating that perhaps the patient needs an adjustment in his or her medication.

But the larger benefit is societal. Once the data is stripped of identifying information, epidemiologists can analyze trends among entire groups of asthma sufferers. From this, they should be able to identify certain environmental and geographical factors--areas where certain plants are present or where certain pollutants are peristent--that precipitate asthma attacks. That could lead not only to a better understanding of asthma, but to a better understanding of the general air quality in a given area.

[Economist]

New rounds are seven times more accurate

One Infantry Brigade Combat Team in Afghanistan has already received the new rounds, known as Accelerated Precision Mortar Initiative cartridges (APMI), and seven more are expected to receive them in the next sixth months. The GPS-guided 120-millimeter mortar rounds will offer infantry commanders precision-strike capability, offering them an alternative to blanketing an area in indirect fire.

That’s a key advantage. U.S. troops operating in places like Afghanistan already walk a tightrope between engaging a dangerous enemy and protecting civilian lives and property, and this fact isn’t lost on insurgents who launch attacks from populated areas in hopes that U.S. troops won’t retaliate. A GPS-guided mortar allows troops to to launch a mortar shells from protected positions into an areas where other friendly troops are operating or where collateral damage is possible with a far higher degree of control and certainty. It's a smarter weapon for a new kind of warfare.

The APMI XM395 cartridge employs a standard 120-millimeter projectile body, but packed in the nose is a GPS receiver and controller that ensures the aerodynamic directional fins guide the shell toward the target. It also contains a multi-functional fuse that can be programmed to detonate upon impact, in the air, or after it penetrates the ground or a structure. Coordinates are dialed into the round using a computer.

The result is a round that is at minimum seven times more accurate than the most accurate round currently fielded, though there is still some room for error--the APMI is expected to hit within about 30 feet of a target at least half the time, not perfect by any means but still a remarkable improvement. That kind of accuracy also offers one more distinct advantage: less rounds fired means more rounds saved, which cuts down on vulnerable resupply missions to troops in combat zones.

[U.S. Army]

Mapmakers have more power than ever. But who are the mapmakers?

The commander cited Google Maps, which had erroneously depicted a stretch of the border in Nicaragua’s favor by as much as 1.7 miles. Google quickly moved to amend the faulty border data and sportingly apologized.

The incident raises some interesting issues concerning the future of mapmaking that, thus far, our brave new digital world hasn’t yet been forced to confront. Whereas cartography – particularly the act (or the art) of drawing political lines on geographical charts – used to be the purview of nations and international bodies, commercial entities like Google, Bing, Mapquest, and other digital services are the principal mapmakers of the 21st century.

Orbiting GeoEye satellites and camera-equipped Google sedans are the Magellans of the digital age, dispatched to explore and catalog -- and most importantly make public -- unprecedented amounts of geographical data via the Web. If anyone wants to locate anything – be it a coffee house, a post office, or an international boundary – users log into Google or Bing, not the U.N. or the U.S. Geological Survey. But these commercial maps are compiled from a variety of sources and often blend government-derived mapping data with user-generated content. As such, they are subject to conflicting information, differences of political opinion and – as the Nicaraguan incident shows – outright error.

“With a lot of these web-based tools, the need for formal training in cartography is going away, and that’s both a good thing and a bad thing,” says Dr. Brian Tomaszewski, an assistant professor in the Department of Information Sciences & Technologies at the Rochester Institute of Technology. It’s good because it creates rich, centralized data compilations that users constantly update. But before that can happen, someone like Google has to build the underlying map, and there’s no single source or authority for global map data to draw from. That leaves companies in the unenviable position of trying to pick and choose the best data and massage it to fit a single geographical template.

In the case of Nicaragua, it turns out that data was simply incorrect. A post on Google’s “Lat Long Blog” explained the error: “Yesterday we became aware of a dispute that referenced the border between Costa Rica and Nicaragua as depicted on Google Maps. This morning, after a discussion with the data supplier for this particular border (the U.S. Department of State), we determined that there was indeed an error in the compilation of the source data, by up to 2.7 kilometers.”

Viewed on Google Maps, however, an incorrect border looks like any other border, and if the U.S. State Department (and, more importantly, Google) says the border is in one place, who is Costa Rica to say it’s not? In strict cartographic sense, the treaty that originally established the border is the final word. But no one locates a border by reading a 150-year-old treaty; people find borders by looking at maps, and in the 21st century people consult maps by opening their Web browsers.

“We look at the computer and say ‘how can it be wrong, it’s on the computer,’” says Dr. Frank Galgano, professor and chairman of Villanova University’s Geography and the Environment Department. It’s to the computer that the world increasingly turns to find just about everything, lending digital mapmakers incredible power to shape users’ geospatial perceptions.

What’s largely missing is the healthy skepticism that users apply to other piecemeal compendia of information like Wikipedia, Galgano says. Google knows its maps contain errors; it says so in the user agreement (you read that closely, didn’t you?). For those people searching for the nearest Starbucks in Lower Manhattan these errors are largely negligible. But for an American hiking near the Iranian border, they can lead to miscalculations with serious consequences.

“People are forgetting to use common sense and critical thinking,” Tomaszewski says. “Google Maps isn’t an official mapping agency like a government. They buy or acquire data and then assemble it into a map. It’s almost frightening to think that militaries or governments might rely on Google as the final word on boundaries or borders between nations.”

But there are a variety of reasons why a government or military might do so, not least of which is the lack of anything better. In the United States, the USGS maintains an extensive collection of publicly available map data accurate down to about 130 feet. Many other nations treat their official maps as state secrets. Still others don’t have the resources to produce accurate maps at all. That makes commercial, publicly available maps like Google’s very attractive, if not any more authoritative.

Why Nicaragua chose to use a Google Map to justify military actions along a tense border is something for the geopolicy wonks to debate. Regardless, the incident embodies the changing nature and impact of cartography in a rapidly digitizing environment where data – often conflicting – is abundant and clearly defined rules are scarce. After all, borders are nothing more than imaginary lines enforced by mutual agreement. Cartography is inexact enough already, and the blurring line between “official” cartography and commercial maps rich in content but low in complexity further compounds that lack of concreteness.

That’s not to say commercial maps don’t carry tremendous value. Their accessibility has revolutionized the way people use maps, particularly as they pertain to commerce. The economic importance of being “on the map” may not be outwardly apparent, but consider the case of Sunrise, Fla.; the community of 90,000 has inexplicably disappeared from Google Maps three times since August of last year. During these “blackouts,” local businesses reported flattening commerce as new customers couldn’t locate them. Online orders ground to a halt for some businesses. After all, how would anyone find a florist or automotive shop that’s not searchable? When Sunrise disappeared from Google Maps, it might as well have disappeared completely.

So what makes a real map in the 21st century? Some would argue that the musty old analog maps tucked into national archives around the world are still the real deal, invested with the authority of governments. But if asked which is more important to their everyday lives, the citizens of Sunrise, Fla., might argue that commercial maps, regardless of inaccuracies or oversimplifications, represent a far greater social and economic utility. To the average person, commercial maps like those compiled by Google, Bing, or Yahoo have become at least as equally important as their “official” counterparts.

The important thing is maintaining a line between the two, and therein lies the problem in a world where data of all kinds is migrating ever more rapidly to the Web and pooling there, waiting for someone to make sense of it.

UTD’s Dr. Dean likens mapmaking’s shift to the commercial, digital realm to the blossoming of user-generated travel sites across the Web. When planning a trip, a user might seek information from established third party reviewers, like magazines or established ratings agencies. But he or she might also troll the Web for social data and customer reviews written by other travelers. Both kinds of data are valuable, he says, but a smart traveler would absorb and use them differently.

“It’s all part of becoming a knowledgeable consumer of maps. The idea that if it’s on a map it’s got to be true is misguided,” Dean says, noting that this is actually a very old problem rather than a new one. As with any data, misuse can lead to debacle, and such mishaps can range in severity from missing an exit on the interstate to interstate warfare. “Someone tried to look at a boundary on Google Maps as if it were a real definitive border and it nearly caused an armed conflict,” Dean says. “That’s as serious as it gets.”

Thus far, the most common fix for GPS dead zones is to employ some kind of inertial measurement unit (IMU) that uses measures your speed and direction and figures your position relative to your last known GPS location. But IMUs can be faulty. Even a tiny error in measuring speed or direction will accumulate over time, so the longer you are without GPS the more inaccurate the IMU estimation. This can lead to serious problems if, say, you are trying to find your way out of a subterranean cave or a Wal Mart.

These IMU errors are usually the result of misreading when the subject is standing still. The person may stop, but the IMU may think the person has taken a few more steps, or is even still moving slowly. So the NC State – CMU team devised a means for IMUs to better calculate when a person is standing still: a radar embedded in the heel of the shoe.

The shoe radar works by tracking the distance between the foot and the ground. If that distance doesn’t change for a given period of time, the system knows the foot is firmly planted and tells the IMU as much. By improving the IMUs understanding of when a person is at a complete standstill, the shoe radar can drastically reduce those accumulation errors.

Installing radar in every pair of shoes you own would probably be a bit over the top. But for people who spend a lot of time underground, especially in dangerous situations – miners come to mind, as do construction workers and engineers working on tunnels and large infrastructure projects – technology that can accurately locate you in a pinch seems like it would be a pretty wise investment.