GPS constellation marches on


You probably didn't notice, but on Feb. 16 the GPS satellite constellation was officially complete with the handover of the last of 12 Block IIF spacecraft (IIF-12 is now officially known as SVN-70) to 50th Space Wing, the GPS operations unit at Schriever Air Force Base, Colorado (more details on that here). Now that the Block IIF spacecraft are on orbit, the next generation of GPS satellites will be the arrival of the first Block III GPS satellites starting with launches in 2017.   

The Block IIF units have more capability compared to earlier GPS satellite models, including:

• Broadcasting L5 "safety of life" navigation signal demonstrated on USA-203
• Broadcasting a new M-code signal
• Doubling in the predicted accuracy
• Better resistance to jamming
• Reprogrammable processors that can receive software uploads
• The first GPS satellites not to have Selective Availability (SA) hardware installed, which degraded civilian accuracy when turned on in the original satellite fleet.  

The 32 Block III's will reportedly have higher power signals, Medium Earth Orbit Search and Rescue (MEOSAR) packages, enhanced ground control, and other improvements.

By Ocean Navigator