Global Positioning System Reference
In-Depth Information
The Block IIF SV is designed for a life of 12 years with a MMD of 9.9 years. It is
backward compatible with the Block IIR capabilities described in Section 3.2.3.6,
including the capability to operate in AutoNav mode. An on-orbit depiction of the
Block IIF SV is shown in Figure 3.13. The nadir-facing side contains a set of UHF
and L-band antennas and other components that are very reminiscent of all of the
previous GPS satellites.
The original IIF contract was for a basic buy of 6 SVs and two options of 15 and
12 SVs for a possible total of 33 SVs. At the time of this writing, GPS JPO projec-
tions indicated that 16 Block IIF SVs will be procured and launched to maintain
the constellation prior to the start of GPS III. The first Block IIF launch is scheduled
for 2007.
3.2.3.8 Block III—Next Generation Satellites
The GPS III program was conceived to reassess the entire GPS architecture as it has
evolved to its present state and determine the correct architecture to lead into the
future. The program has two main goals: reduce the government's total ownership
costs and provide sufficient architectural flexibility to satisfy evolving requirements
through 2030. On a more technical side, GPS III is expected to provide submeter
position accuracy, greater timing accuracy, a system integrity solution, a high data
capacity intersatellite crosslink capability, and higher signal power to meet military
antijam requirements. Two system architecture/requirements development (SARD)
studies were performed in 2001-2002 by contractor teams led by Boeing and
Lockheed Martin, resulting in a baseline concept description from each team. (An
unfunded study was conducted by Spectrum Astro.) After a short extension on those
Figure 3.13
Block IIF SV ( Source: The Boeing Company. Reprinted with permission.)
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