Posts Tagged ‘global positioning system’
Ground-Based Version of Satellite GPS Could Make Positioning Technology Accurate to Inches Anywhere
Locata’s vision works more or less just like the existing GPS system, except that the transmitters are ground-based rather than orbiting. GPS satellites, each containing a highly-precise atomic clock that is synchronized with its counterparts elsewhere in the sky, emit signals that GPS receivers can pick up. Each signal is timestamped, and by calculating its distance from more than one of these satellites, a GPS-enabled device can triangulate its own position on the globe.
But atomic clocks are expensive, and keeping a ground-based network of transmitters synchronized is extremely difficult--which is why this hasn’t been done before. Locata gets around this problem by installing timing chips that are much less accurate--and much cheaper--than atomic clocks in its LocataLite transmitters (which themselves are about the size of a hardback book, rather than the size of a satellite).
The trick is that the LocataLites don’t attempt to keep the correct time as measured by some external standard. Instead, they simply keep in sync with each other. Each LocataLite adjusts its outgoing signal to reflect the timing of the signal it picks up, creating a feedback loop that ensures that while the network will get out of sync with external time, the LocaLites will at least remain in sync with one another. And that’s really what’s important.
The LocataLites broadcast on the same frequency as Wi-Fi, so all kinds of devices are already equipped to pick up the signals. And because the technology can locate devices down to less than an inch, it could make a range of applications--augmented reality, precision cargo tracking, self-driving cars--way more precise than they are now.
[]
Radar Shoes Could Help Locate Users Where Satellite Signals Won’t Go
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.
To Thwart Predators, South Korea Is Issuing GPS Devices to Schoolchildren
Starting in October, about 1,200 elementary school children in Anyang City, south of Seoul, will receive matchbox-sized GPS-embedded beepers. The devices can notify authorities of the kids' location and activate surveillance cameras.
The move comes a month after a 44-year-old habitual sex offender was arrested and accused of kidnapping and sexually assaulting an 8-year-old girl. That case, as well as other crimes against children, shocked the country and mobilized the government to declare war on child molesters.
The 8-year-old girl was abducted from her school, and officials have stepped up school security in response. After a trial run, the government might expand the GPS devices to the rest of the country, AFP says.
[]