256
4 Navigations from Ground to Space
intended to control launch and early orbit operations and the on-orbit checkout of
all GPS III satellites. It is a subset of the Block-1 providing the hardware, software
and cyber-security base for the Block-1. The Block-1 fields the operational capability to control all legacy satellites, civil signals and military signals, as well as the
modernized military signals, the modernized civil signal, the aviation safety-of-flight
signal, the GPS III satellites and the globally compatible signals, to fully meet information assurance and cyber-defense requirements. The Block-2 fields the advanced
operational capability to control the advanced features of the modernized military
signals. The OCX program represents a critical part of the GPS modernization, and
its specifically final capabilities are as follows:
(1) To control and manage the legacy GPS satellites and the next generation of
GPS III satellites, while enabling the fully array of military signals.
(2) To build on a flexible architecture that can rapidly adapt to the changing needs
of current and future GPS users allowing immediate access to the GPS data
and constellation status through secure, accurate and reliable information.
(3) To provide the war fighter with more secure, actionable and predictive
information to enhance situational awareness.
(4) To enable new modernized signals like L1C, L2C and L5, and has M-code
capability, which the legacy system is unable to do.
(5) To provide significant information assurance improvements over the current
program including detecting and preventing cyber-attacks, while isolating,
containing and operating during such attacks.
(6) To support higher volume near real-time command and control capabilities.
At present, the GPS control network is composed of 2 master control stations, 16
monitor stations and 12 injection stations, as shown in Fig. 4.11. The master control
station, located at Schriever Air Force Base (AFB) in Colorado Springs, is the central
control node for the GPS constellation, which is operated and managed by the 2nd
Space Operation Squadron (2SOPS) of the U.S. Air Force, while the alternate master
control station is located at Vandenberg AFB in California. Using the information
from the monitor stations, the master control station computes the orbit and clock
parameters of GPS satellites, generates the navigation message, monitors the integrity
of navigation message and system, and evaluates the health status of GPS constellation. The 2SOPS uses the master control station to perform the satellite’s maintenance
and anomaly resolving. In the event of a satellite failure, the master control station can
reposition the satellites to maintain an optimal GPS constellation. Six of the sixteen
monitor stations are specially deployed by the U.S. Air Force, respectively, located at
Schriever AFB in Colorado Spring, Hawaii and Cape Canaveral in Florida within the
US, as well as Ascension Island in the South Atlantic Ocean, Diego Garcia Island in
the central Indian Ocean and Kwajalein Atoll in the west-central Pacific Ocean, for
tracking the GPS constellation. The other ten monitor stations are deployed by the
U.S. National Geospatial-intelligence Agency (NGA), respectively, located at Fairbanks in Alaska and USNO Washington within the US, as well as Quito in Ecuador,
Buenos Aires in Argentina, Hermitage in the United Kingdom, Manama in Bahrain,
Pretoria in South Africa, Osan in South Korea, Adelaide in Australia and Wellington
4 Navigations from Ground to Space
intended to control launch and early orbit operations and the on-orbit checkout of
all GPS III satellites. It is a subset of the Block-1 providing the hardware, software
and cyber-security base for the Block-1. The Block-1 fields the operational capability to control all legacy satellites, civil signals and military signals, as well as the
modernized military signals, the modernized civil signal, the aviation safety-of-flight
signal, the GPS III satellites and the globally compatible signals, to fully meet information assurance and cyber-defense requirements. The Block-2 fields the advanced
operational capability to control the advanced features of the modernized military
signals. The OCX program represents a critical part of the GPS modernization, and
its specifically final capabilities are as follows:
(1) To control and manage the legacy GPS satellites and the next generation of
GPS III satellites, while enabling the fully array of military signals.
(2) To build on a flexible architecture that can rapidly adapt to the changing needs
of current and future GPS users allowing immediate access to the GPS data
and constellation status through secure, accurate and reliable information.
(3) To provide the war fighter with more secure, actionable and predictive
information to enhance situational awareness.
(4) To enable new modernized signals like L1C, L2C and L5, and has M-code
capability, which the legacy system is unable to do.
(5) To provide significant information assurance improvements over the current
program including detecting and preventing cyber-attacks, while isolating,
containing and operating during such attacks.
(6) To support higher volume near real-time command and control capabilities.
At present, the GPS control network is composed of 2 master control stations, 16
monitor stations and 12 injection stations, as shown in Fig. 4.11. The master control
station, located at Schriever Air Force Base (AFB) in Colorado Springs, is the central
control node for the GPS constellation, which is operated and managed by the 2nd
Space Operation Squadron (2SOPS) of the U.S. Air Force, while the alternate master
control station is located at Vandenberg AFB in California. Using the information
from the monitor stations, the master control station computes the orbit and clock
parameters of GPS satellites, generates the navigation message, monitors the integrity
of navigation message and system, and evaluates the health status of GPS constellation. The 2SOPS uses the master control station to perform the satellite’s maintenance
and anomaly resolving. In the event of a satellite failure, the master control station can
reposition the satellites to maintain an optimal GPS constellation. Six of the sixteen
monitor stations are specially deployed by the U.S. Air Force, respectively, located at
Schriever AFB in Colorado Spring, Hawaii and Cape Canaveral in Florida within the
US, as well as Ascension Island in the South Atlantic Ocean, Diego Garcia Island in
the central Indian Ocean and Kwajalein Atoll in the west-central Pacific Ocean, for
tracking the GPS constellation. The other ten monitor stations are deployed by the
U.S. National Geospatial-intelligence Agency (NGA), respectively, located at Fairbanks in Alaska and USNO Washington within the US, as well as Quito in Ecuador,
Buenos Aires in Argentina, Hermitage in the United Kingdom, Manama in Bahrain,
Pretoria in South Africa, Osan in South Korea, Adelaide in Australia and Wellington