The GPS or Global Positioning System is a globalnavigation system used for military and civilian applications alike.
As a positioning system, GPS allows users to map waypoints, tracking their position on a map to within a few meters of their exact location. Civilian use GPS systems are made by companies such as Magellan, Garmin and Trimble.
GPS receivers come in a variety of consumer formats, and today can be found in cars, watches, phones boats and planes. Major manufacturers include Trimble, Garmin and Leica, low-end, hand-held consumer units are often available at less than $100 per unit.
GPS signals can also be affected by multipath reflections of the radio signals off the ground and/or surrounding structures (buildings, canyon walls, etc). For long delay multipath signals, the receiver itself can filter the signals out. A variety of receiver techniques, most notably Narrow Correlator spacing, have been developed to mitigate multipath errors.
The author would have loved to have used GPS years ago in college. We had a class where we used maps and compasses. We were given precise coordinates and had to plot a course through woods and streams and swamps to find and sign in at specific latitude and longitude coordinates. Today, this sport, now called "geocaching", is a popular activity, particularly for outdoor hiking enthusiasts.
When it was first deployed, GPS included a feature called Selective Availability (or SA) that introduced intentional errors of up to a hundred meters into the publicly available navigation signals, making it difficult to use for guiding long range missiles to precise targets. Additional accuracy was available in the signal, but in an encrypted form that was only available to the United States military, its allies and a few others, mostly government users.
During the Gulf War, the shortage of military GPS units and the wide availability of civilian ones among personnel resulted in disabling the Selective Availability. In the 1990s the FAA started pressuring the military to turn off SA permanently. This would save the FAA millions of dollars every year in maintenance of their own, less accurate, radio navigation systems. The military resisted for most of the 1990s, but SA was eventually turned off in 2000 following an announcement by then US President Bill Clinton, allowing all users to enjoy nearly the same level of access.
GPS allows the military to accurately target its missile arsenal, largely composed of cruise missiles and precision-guided munitions. This was born out by the use of SOFLAM (Special Operations Forces Laser Acquisition Markers) targeting during the attacks on Tora Bora in Afghanistan. It also improves the accuracy of the US submarine launched ballistic missiles by providing precise locational information to the submarine commanders. Finally, command and control over troops is improved because commanders know precisely where their troops and the enemy are located on the battlefield.
Atomic clocks on the GPS satellites are set to "GPS time", which is the number of seconds since 00:00:00 UTC, January 6, 1980. UTC is short for Coordinated Universal Time. Today, GPS time is 14 seconds ahead of UTC, because it does not follow leap seconds. That's why new GPS units initially show the incorrect time after achieving a GPS lock for the first time. However, this is usually corrected on the display within 15 minutes once the UTC offset message is received for the first time.
The US military has developed the ability to locally deny GPS (and other navigation services) to hostile forces in a specific area of crisis without affecting the rest of the world or its own military systems. Such Navigation Warfare uses techniques such as local jamming to replace the blunt, world-wide degradation of civilian GPS service that SA represented.
In late 2005, the US government introduced the first in a series of new generation GPS staellites offering new capabilities. Chief among these is a second civilian GPS signal called L2C for greater accuracy and reliability.
1. AG-STEER Auto Steer System For Precision Agriculture The AG-STEER is an Automatic Hydraulic Steering system that allows you to focus on the ... Auto Steer GPS - AG-STEER. The AG-STEER is an Automatic Hydraulic Steering system that ...
2. Affordable Auto-steer Once out of the price range of many growers, GPS auto-steer systems for tractors are now more affordable. But don't buy the cheapest system available and expect the ...
3. GPS Auto-Steer Vehicles GPS Review GPS Auto-Steer Vehicles. Dec. 22. 2005. Yes, it is coming. AutoFarm is introducing a system ... The system uses GPS signals to automatically steer vehicles with an ...
4. MIDWEST AUTO STEER - Agricultural GPS Steering Ag Leader & AutoFarm Alliance. Jerry Sampson Joel Nelson Ron Frank. jerry@midwestautosteer.com joel@midwestautosteer.com ron@midwestautosteer.com ...
7. GPS Auto Navigator China Manufacturers China GPS Auto Navigator Manufacturers Verified with 3 or more face-to-face visits by Global Sources Choose Verified China GPS Auto Navigator Manufacturers & Suppliers
8. Headsight - Auto Steer Auto Steer. TrueSight-True Row Guidance. Truesight is a high accuracy row-crop autosteer ... GPS, therefore can be installed on any combine once a steering valve ...
11. Auto GPS Navigator China Manufacturers China Auto GPS Navigator Manufacturers Verified with 3 or more face-to-face visits by Global Sources Choose Verified China Auto GPS Navigator Manufacturers & Suppliers
13. Auto Steering Wheels-Auto Steering Wheels Manufacturers ... Choose quality Auto Steering Wheels Manufacturers, Suppliers, Exporters at alibaba.com. ... auto alloy wheel, auto custom wheel, auto wheel alignment, gps auto steer, zf auto ...
16. TeeJet - Auto Steering Products Products used for on board automated steering utilizing GPS navigation. They range in their feature sets and navigation accuracy.
17. Auto-Guide Steering Systems - Sauer-Danfoss Auto-Guide Steering Systems ... Sauer-Danfoss offers superior solutions for state-of-the-art steering systems that interface with the leading GPS suppliers in the market. ...
18. GPS-Based Auto-Guidance Clinic GPS and Auto Guidance systems are cost efficient and you can get your ... The Trimble light box and auto-steer you can make just about and line with ...
19. Montgomery - Transactions GPS guidance and auto-steering assist farmers to precisely map and navigate ... BEELINE pioneered hands-free auto-steering which improves efficiencies and ...
20. Shipyard Giants | GPS World The sinusoidal pattern of wheel deviation is typical in auto-steering mode. ... The GPS-RTK auto-steering system described in this article was ...
24. RTK Farming RTK Farming, GPS Systems for Agriculture offering GPS auto-steer and Controlled Traffic Farming for Cambridgeshire, cost effective RTK networks in East Anglia
25. Multi Farming Systems 1. Can I fit GPS auto steer to my Multiplanter? Yes, this will give you much better control over undulating ... 2. I want to be able to steer my Multiplanter while end towing. ...
26. Precision Farming Tools: GPS Navigation - Virginia ... GPS + Auto-Steer Navigation. More advanced navigation systems (auto-steer systems) possess ... Auto-steering is accomplished with a device mounted to the steering ...
29. Landmark GPS Auto-Steer Technology--Landmark Agronomy is rapidly adapting GPS auto-steer guidance ... Auto-steer ensures you receive a high-quality application and provides you with the ...
30. Investor Presentation uncertainties pertaining to Hemisphere GPS and its business is available in the ... (Payback analysis for GPS / Auto-steering effectively one season) ...
32. Hemisphere GPS Acquires Steer-by-Wire Company | GPS World Canada's Hemisphere GPS has entered into a definitive agreement to acquire all the ... software developer providing GPS guidance and auto-steering applications for agriculture ...