JIMI Electronic

This tutorial is about selecting a  personal tracking device  and getting started using it. Choosing a GPS receiver can be quite an overwhelming experience. If you look at handheld, portable GPS receivers that currently offer, you’ll have around 50–60 GPS receivers to choose from. That’s a lot of choices. And that’s only the beginning. After you purchase one, you still need to find out how to use it. This tutorial should take some of the confusion out of buying a GPS receiver and help you come up to speed using it. When it comes to selecting a GPS receiver, I won’t recommend that you buy a particular brand or model or tell you which is best for hiking, geocaching, or other activities. Rather, I follow more of a Socratic method, in which I ask you a number of questions that should help you make a pretty good and informed purchasing decision. Before you purchase a GPS receiver, you should spend some time kicking the proverbial tires. Don’t rush out and buy a receiver based ...

While you can get more accurate fixes from such a system, it requires a number of additional, time-consuming steps, after data collection. Once you know the source of the differential corrections file, you have to get it, load it onto your computer, and execute software to produce the final corrected file. Wouldn’t it be nice if the  GPS tracker  simply gave accurate positions at the time you took the data? Further, there are some applications in which there simply isn’t time to postprocess GPS fixes–bringing a ship into a narrow harbor, for one example. Well, actually there is a way to provide instantaneous, accurate fixes: Real-Time Differential GPS. Getting Corrections for GPS Measurements – Right Now! Real-Time Differential GPS (RDGPS) may be approached in several ways: • The user can set up a base station over a known point and arrange for transmission of a radio signal from the base station to roving receivers. • The user’s  GPS Tracking Device ...

GPS might be divided up in the following way: The Earth The first major component of GPS is Earth itself: its mass and its surface, and the space immediately above. The mass of the Earth holds the satellites in orbit. From the point of view of physics, each satellite is trying to fly by the Earth at four kilometers per second. The Earth’s gravity pulls on the satellite vertically so it falls. The trajectory of its fall is a track that is parallel to the curve of the Earth’s surface. The surface of the Earth is studded with little “monuments”– carefully positioned metal or stone markers–whose coordinates are known quite accurately. These lie in the “numerical graticule” which we all agree forms the basis for geographic position. Measurements in the units of the graticule, and based on the positions of the monuments, allow us to determine the position of any object we choose on the surface of the Earth. Earth-Circling Satellites The United States GPS design calls for a t...

While this is a text on how to use GPS in GIS–and hence is primarily concerned with positional issues, it would not be complete without mentioning what may, for the average person, be the most important facet of GPS: providing Earth with a universal, exceedingly accurate time source. Allowing any person or piece of equipment to know the exact time has tremendous implications for things we depend on every day (like getting information across the Internet, like synchronizing the electric power grid and the telephone network). Further, human knowledge is enhanced by research projects that depend on knowing the exact time in different parts of the world. For example, it is now possible to track seismic waves created by earthquakes, from one side of the earth, through its center, to the other side, since the exact time may be known worldwide. GPS AND GIS The subject of this blog is the use of GPS as a method of collecting locational data for Geographic Information Systems (GIS). Th...

IN WHICH you are introduced to facts and concepts relating to the NAVSTAR Global Positioning System and have your first experience using a  electronic tracking devices   .  A sports club in Seattle decided to mount a hunting expedition. They employed a guide who came well recommended, and whose own views of his abilities were greater still. Unfortunately, after two days, the group was completely, totally lost. “You told me you were the best guide in the State of Washington,” fumed the person responsible for hiring the guide. “I am, Iam” claimed the man defensively. “But just now I think we’re in Canada.” Stories like the one above should be told now (if at all), before they cease to be plausible. Actually, even at present, given the right equipment and a map of the general area, you could be led blindfolded to any spot in the great out-of-doors and determine exactly where you were. This happy capability is due to some ingenious electronics and a dozen billion dollars...

Remember the story of Hansel and Gretel, the kids who dropped breadcrumbs in the forest to try to find their way back home? Their story would’ve had a different ending if they had a GPS receiver because all newer GPS receivers leave electronic breadcrumbs (called tracks or trails depending on the manufacturer) while you travel. Every so often, the GPS receiver saves the coordinates of the current position to memory. This series of tracks is a track log or track history. (Because various GPS models handle tracks differently, check your user manual for specific details.) Note these differences between tracks and waypoints: Names and symbols : Although tracks and waypoints are both location data points, tracks don’t have names or symbols associated with them and can’t be edited in the GPS receiver.   Autocreation: Unlike waypoints  — that you need to manually enter — tracks are automatically created whenever a GPS receiver is turned on (that is, if you have the tr...

GPS is such an extremely important technology! It is no exaggeration to say that GPS is revolutionizing aspects of many fields, including surveying (slashing the costs of many kinds of survey efforts and bringing surveying to parts of the world where surveys are nonexistent, highly inaccurate, or long since outdated), the natural resource fields (providing rapid and far more accurate collection of field natural resource data of many kinds), and municipal planning (providing for the updating of all kinds of records based on accurate field checking), to name only a few.  electronic tracking device  is making practical the kinds of data collection which were simply out of the question only a few years ago because the necessary skilled teams of field personnel were unavailable and the costs of accurate field data collection were beyond the means of virtually all organizations which needed these kinds of data.  GPS is changing all that. Use of the kinds of methods taught ...

The first of these unconventional GPS applications to be seriously examined was precise orbit determination (POD) in support of high precision ocean altimetry. A global differential GPS technique for achieving sub-decimeter orbit accuracy on the joint U.S.- French TopexlPoseidon mission was first proposed at the Jet Propulsion Laboratory in 1981. The basic elements of the proposed differential GPS system-a small global ground network, a precision flight receiver, the GPS constellation, and an analysis center-are depicted in the picture below. Over the years, a variety of refinements to the proposed orbit estimation technique, evaluated through simulation studies and covariance analysis, revealed the surprisingly rich potential of  tracking device  for few-centimeter tracking of orbiters at low altitudes. The Topex/Poseidon ocean altimetry satellite was launched into a 1300 kIn orbit on an Ariane rocket in August of 1992. It carried an experimental dual-frequency P-code ...

With the recent completion of the Global Positioning System constellation and the appearance of increasingly affordable spaceborne receivers, GPS is moving rapidly into the world of space flight projects. Indeed, owing to the great utility and convenience of autonomous onboard positioning, timing, and attitude determination, basic navigation receivers are coming to be seen as almost indispensable to future low earth missions. This development has been expected and awaited since the earliest days of GPS. Perhaps more surprising has been the emergence of direct spaceborne GPS science and the blossoming of new science applications for high performance geodetic space receivers. Applications of spaceborne GPS to Earth science include centimeter-level precise orbit determination (POD) to support ocean altimetry; Earth gravity model improvement and other enhancements to GPS global geodesy; high resolution 2D and 3D ionospheric imaging; and atmospheric limb sounding (radio occultation) to...

A GPS receiver is one of the most accurate clocks in the world, if it has continual access to the satellites. The forte of a clock in a  tracking device  is short-term accuracy, not long-term consistency. People who really want to know exactly what time it is can set up a base station over a known point and analyze GPS signals for time instead of position. GPS time does differ from UTC time by an integer number of seconds, less than 20 for the near future. There are many applications for which coordinated time is vital. Examples: making the telephone system, the banking system, and the Internet, on which the World Wide Web is based, run smoothly. There will be an increasing number of applications in which GPS signals control equipment directly, rather than going through a human “middle-man.” In such joint GPS/GIS uses as fertilizer or pesticide application, the automated system may steer the tractor while the farmer rides along simply for reasons of safety. Carving out ro...