In 1985, ten experimental Block-I satellites were up. A complete "constellation" of 24 satellites was in orbit by January 17, 1994.
In early years, the US military made the civilian application purposefully less powerful than it could. But since August 2000, the GPS civilian application provides the accuracy of GPS signals to within 2 meters (6 ft). Fact is, GPS accuracy can be improved further, to about 1 cm (half an inch) over short distances, using techniques such as Differential GPS (DGPS).
GPS has become a vital global utility, indispensable for modern navigation on land, sea, and air around the world, as well as an important tool for map-making, and land surveying. GPS also provides an extremely precise time reference, required for telecommunications and some scientific research, including the study of earthquakes.
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.
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.
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.
Because GPS is as much an accurate time keeper as a locator, one of the most common applications for GPS units is as a reference clock for time code generators or NTP clocks. For instance, when monitoring earthquakes, each seismic sensor can be synched with the GPS system to provide a synchronized, precise time source for measurements.
One of biggest problems for GPS accuracy is that changing atmospheric conditions change the speed of the GPS signals unpredictably as they pass through the ionosphere. The effect is minimized when the satellite is directly overhead and becomes greater toward the horizon, as the satellite signals must travel through the greater "thickness" of the ionosphere as the angle increases. Once the receiver's rough location is known, an internal mathematical model can be used to estimate and correct for the error.
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.
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YouTube - PSP GPS v1Hy guys this is just 4 enthusiasts. If you don't like troubles get a GPS. This is my best advise, best whishes. Just 4 info, I used a slim PSP, but mapthis c...
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GPS for Sony PSP coming to USThe GPS receiver for the Sony PSP is about to find its way out of Japan and into US gamers' hands. ... only thing would be if the GPS would fit on my PSP in the mount. ...
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PSP GPS-290 + Map This! In Action | PSP Hacks · PSP Go ...Neubit, notorious Acidmods gang member, known best for his modding skills, is doing something a little different this time 'round... Below is a video
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Psp Gps V1 - VideoHy guys this is just 4 enthusiasts. If you don't like troubles get a GPS. This is my best advise, best whishes. Just 4 info, I used a slim PSP, but ma. Watch Video ...
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YouTube - GPS PSPWatch this video in a new window. GPS PSP. Hello, you either have JavaScript turned off or ... GPS is very good:-) and he also said that it is hoax that sony GPS ...
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GPS for PSP finally goes on sale -- EngadgetWe've rumored, ogled, and previewed, but it's time to get official, folks. The GPS Receiver for the PSP launches Thursday in Japan, for the
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PSP GPS system announced for US releaseFinally, GPS is coming to PSP. First details from CES. ... Shippwreck87, on 01/07/2008, -0/+14With this GPS announcement on top of already knowing about Crisis Core, ...
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Zenrin GPS navigation on Sony PSP -- NaviGadgetRemember that Zenrin GPS navigation for PSP? It looks like they were demonstrating their late comer GPS navigation software program Sony PSP. ...
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