Ground tracks of 30 NAVSTAR GPS satellites. The time span covered by each ground track is five hours (time rate is 1000x real time).
This month, the first Block IIF GPS satellite will launch from Cape Canaveral.
It will be the fist of 12 new ones, which U.S. Air Force ordered at Boeing and this campaign is a part of the GPS Modernization Program.
Boeing delivered also the 39 other SV's (Block I and Block II/IIA).
The new GPS IIF features twice the navigational accuracy of the current satellites (advanced atomic clocks greatly improving performance and giving the control segment greater visibility into the health of the units) and should deliver more robust signals for aviation and SAR (probably also for Photogrammetry and Surveyors), meaning the new L5 signal.
The new Block of SV's id designed for a 12 years life time period.
Navstar GPS Block IIF will be the end of the current generation of GPS satellites.
Actually, these new satellites each transmit three civilian GPS signals (we’ve typically been making do with just one for years) including a military-strength transmission that should enable autopilots to land with zero visibility.
A three-signal world will mean always-on GPS that’s accurate to within 3 feet (even indoors and in concrete urban canyons).
An official military announcement also laid out the 24+3 (“Expandable 24”) consisting to move three existing GPS satellites to new orbit locations will have a profound effect on GPS capabilities for all civil, commercial, and military users worldwide.
In the future, the next-generation GPS system (Block IIIA) will introduce new capabilities to meet higher demands of military and civilian users.
The system is looking ahead to its first launch in 2013.
Note : Galileo is still coming up (2014)
Block IIIA will offer the opportunity for a cross-linked command and control architecture, allowing the entire GPS constellation to be updated from a single ground station instead of waiting for each satellite to orbit into view of a ground antenna.
Block IIIA will also support a new L1C civil signal, and a spot beam antenna that provides resistance to hostile jamming while improving its accuracy and integrity.
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