TheUS Global Positioning System (GPS) consists of
a constellation of 24 satellites that emit radio signals
for reception by specially designed devices.
If signals from 4 or more of these satellites are
picked up by a GPS device, it can determine its location
with high, reliable accuracy.
The orbits are arranged such that there are, in
fact, always at least 4 satellites visible from
any point on the surface of the earth.
President Clinton announced at the
beginning of May 2000 that the GPS signals would
no longer be degraded for civilian receivers. Now
these civilian devices can obtain location accuracy
of 15m (~50ft) horizontally (100m previously)
and 100m (328ft) vertically.
GPS devices are now available at prices as low
as $100. The low end devices provide basic features
such as current position, distance and direction to
a set point, current speed, trip distances, track
logs, etc.
..
Here's a video about the treasure hunting game of
GEOCaching.
More expensive devices provide map features such
as showing your current location on a map display.
Also, they can guide you to a given address. They
also have bigger, more sensitive antennas for faster
response. Some portable units can also be connected
to cigaretter lighters for power.
Comment: I did not include
GPS as a HobbySpace topic initially because, like Direct-to-Home
TV, I thought the space aspect of GPS was too hidden
and irrelevant to the user. However, after using and
enjoying my own handheld GPS navigator, I changed my
mind.
When I first turn on my navigator, for example, the
display shows the expected positions of GPS satellites
in range and then gradually indicates which ones have
been detected. Until a minimum number are found, it
cannot find its position. As I move around I must avoid
obstructing the view of the sky if the device is to
keep the position updated. I continually return to the
display to see how many satellites are currently detected.
So my GPS navigator makes me quite aware of the satellites
above me. This is squarely in the HobbySpace
spirit - promoting those activites that involve us,
i.e. the general public, with the space infrastructure
and make us aware of its benefits.
An introductory overview of GPS from the Air Force.
"..treasure hunting game. Armed with
a Global Positioning System (GPS) device and
coordinates, you can locate treasures that others
have hidden in unusual places."
Hiking
Don't get lost. Mark waypoints
along your way through unfamiliar territory.
Or, with the right maps, plan out your hike
by downloading a route of waypoints to guide
your trip.
Mark that beautiful, but isolated, vista
in the mountains so that you can find your way
back to it next time.
Avoid getting lost in snow "whiteouts".
Boating
Boaters, especially, sea-going ones, have
long used GPS for navigation.
Kayaker & canoers can save their strength
by going the straightest route on a big lake.
They can also find their way when out of sight
of land or along unfamiliar shorelines and can
locate the spots reported best for portage.
Car Travel
Several commercial units for cars display
your position on a map, which is very helpful
for travel in unfamiliar cities, on back roads,
and at night.
If you have a breakdown in a remote area,
you can report your exact location by cell phone.
Fishing
Find your way back to that rich but secluded
fishing hole you stumbled upon.
Hang Gliding
While vertical precision is not sufficient
(~100m) for altitude determination, GPS will
provide your horizontal position during your
flight and at your landing point
Recreational
Activities
GPSgames.org
- lots of info on various games with GPS
Geocaching
- The Official GPS Cache Hunt Site - "treasure
hunting game. Armed with a Global Positioning System
(GPS) device and coordinates, you can locate treasures
that others have hidden in unusual places. "
Similar to the Letterboxing
game, which uses compass and clues to locate hidden
treasures.
Everytrail
- The GPS Travel Community - allows you to upload
your GPS data along your trips and see the trail displayed
on a Google Map. Plus you can pinpoint spots where
you took pictures and display those as well.
Degree Confluence
Project - travel to & photograph every integer
longitude-latitude crossing points on earth
US
Tri-State Index - visit significant map locations
such as points where three or more states meet.
SWIFT WX --
Track your position over any weather map using GPS
and monitor severe weather in real-time. Useful for
Storm Chasers.
Amsterdam
Real Time - residents of Amsterdam wear a GPS
that reports their location to a central station that
maps out the density of people in the city.
Peer-to-Peer Communication
& Positioning
New walkie-talkie systems include a GPS locator built
in. This will allow people not only to talk with but
easily to follow the current position of the other person.
A display will show the position of the person relative
to that device.
These systems will be useful for both serious and recreational
activities. For example, search and rescue teams in
a wilderness area could keep track of each other.
Or a family camping in the mountains can both talk
to and keep track of the kids if they go off exploring.
GPS4Fun -
A commercial site dedicated to consumer applications
of GPS.
Resources
GPS:
A New Constellation
This National Air & Space Museum site provides lots
of information on the history, technical workings and
applications of the GPS system.
GPS
World
Online site of the magazine devoted to GPS and Glosnass.
Link lists include:
A waypoint, sometimes
called landmark, provides the coordinates, e.g.
lattitude and longitude, of a geographic location and
is given a name. The location could be a road crossing,
a mountain peak, etc.
With a many of the mapping programs you can access
up to waypoints throughout the world. A table of waypoints
would show each waypoint in a line entry with columns
for a description, type (i.e. school, church, stream,
etc.), longitude/lattitude, elevation and more.
With a program you can build a route by choosing
the waypoints from the table for a hike or drive and
then download the route into compatible GPS navigators.
Conversely, waypoints that you have entered into your
navigator during a trip can be uploaded into a program
and saved to disk.
OpenMap(tm)
"an Open Source JavaBeans TM based programmer's
toolkit. Using OpenMap, you can quickly build applications
and applets that access data from legacy databases
and applications. OpenMap provides the means to allow
users to see and manipulate geospatial information."
Fritz's
Software Linux GpsDrive "is a car (bike, ship,
plane) navigation system. GpsDrive displays your position
provided from your NMEA capable GPS receiver on a
zoomable map, the map file is autoselected depending
of the position and prefered scale..."
TopoGrafix
Topografix offers programs to gather, organize, manipulate,
and download/upload waypoints.
ACME
Mapper - enter Lat/Long and get a map around that
point.
GPS
- Commercial Activity
The creation of a commercial GPS industry has been
slow but steady. The total GPS industry has revenues
of about $12 billion per year according to the Economist
magazine (March 14, 2002).
Handheld consumer GPS receivers are now available for
as little $100. Boats and aircraft have long used GPS
postioning and now there are systems also available
for cars.
New applications are also appearing such as for cell
phone location.
Micro-GPS
A new GPS business involves locating cell phone from
someone making an emergency call. Minature GPS receivers
can now be placed in the phones to provide the position
information:
Also, GPS recievers are becoming small enough for wrist-watches
and other micro-applications.
