|Sep 19, 2007|
The White House acknowledged that this was following on the decision in 2000 to turn Selective Availability off. "Although the United States stopped the intentional degradation of GPS satellite signals in May 2000, this new action will result in the removal of SA capabilities, thereby eliminating a source of uncertainty in GPS performance that has been of concern to civil GPS users worldwide," the statement said.
In simple terms, GPS satellites currently issue two different sets of signals used for determining location: one for the U.S. military and its allies, dubbed the Precise Positioning Service, or PPS, and one for civilian use, dubbed Standard Positioning Service, or SPS. PPS actually comprises two signals and is encrypted, whereas SPS only uses one and is unencrypted; it was designed from the start to be less accurate than PPS. When GPS came about, the military — the GPS satellite fleet is maintained through the U.S. Air Force — didn't want its own technology being used against it in a conflict, so it intended to make the civilian signal less accurate.
Early on, however, SPS proved more accurate than was comfortable for the military, so it introduced Selective Availability (SA). SA degraded the accuracy of the civilian signal on a global basis by introducing intentional timing errors into the civilian signal.
Back in 2000, the U.S. government decided to turn off SA indefinitely, which is one of the factors in the growing adoption of GPS technology in consumer electronics today. This latest pronouncement from Washington D.C. effectively makes the policy change with regard to SA a permanent one.
The U.S. military says SA is no longer necessary, as it has a range of capabilities and technology to implement regional denial of service of civilian GPS signals when needed in the area of conflict — which is why it originally recommended doing away with SA back in 2000. Furthermore, since the advent of GPS, a range of technologies including supplemental satellite and ground-based navigation systems (such as DGPS, WAAS and EGNOS) have grown up to improve the accuracy of civilian GPS, essentially rendering SA moot.
Furthermore, the U.S. Air Force has acknowledged that a recent upgrade to the GPS ground control system will in the future provide a new "security architecture" for supporting troops in combat.
Release Date: September 10, 2007 For Immediate Release Office of the Press Secretary Contact: 202-282-8010
The Department of Homeland Security (DHS) released today the draft National Response Framework (NRF), successor to the National Response Plan, for a 30-day public comment period. The Framework, which focuses on response and short-term recovery, articulates the doctrine, principles and architecture by which our nation prepares for and responds to all-hazard disasters across all levels of government and all sectors of communities. The Framework is responsive to repeated federal, state and local requests for a streamlined document that is shorter, less bureaucratic and more user-friendly.
The Framework is intended for senior elected and appointed leaders, such as federal agency heads, state governors, mayors, tribal leaders and city managers. Simultaneously, it informs emergency management practitioners by explaining the operating structures and tools routinely used by first responders and emergency managers at all levels of government.
Twenty-seven states, including Indiana, have formally endorsed NSGIC's Imagery for the Nation (IFTN) proposal and more are rolling in daily. Indiana would benefit from the IFTN program by gaining an equitable cost-share in a sustainable statewide high-resolution imagery program similar to the 2005 Indiana Orthophotography Project. Please help us spread the word...
The Nation will have a sustainable and flexible digital imagery program that meets the needs of local, state, regional, tribal and federal agencies.
Get the latest brochure for an "official" explanation of the Imagery for the Nation initiative. A poster from the Spring 2006 edition of ArcNews helps to visually describe Imagery for the Nation. Our briefing sheet on the initiative will help you make the right points quickly when working with elected and appointed officials. You can use this slide presentation or its individual slides to give a presentation on the program to your constituent groups. The results of the National Survey are also available for your use in advocating for Imagery for the Nation. The following briefing sheet describes the Federal Cost Benefit Analysis (CBA) study that is a critical step in the evolution of the Imagery for the Nation initiative.
NSGIC is working with its member states, federal organizations and stakeholder associations to create a new nationwide aerial imagery program. The program will collect and disseminate standardized multi-resolution products on "set" schedules. A chronology of the milestones is available to help you understand the evolution of this program.
What you can do to help
Spread the word using the latest informational materials above. It is critical that local, state, regional, and tribal governments approach their respective Congressional delegations and voice support for this program. Organizations already helping NSGIC to lead or endorse the initiative include: Federal Geographic Data Committee; National Digital Orthophoto Program; Western Governor's Association; National Association of Counties; Urban/Regional Information Systems Association; and University Consortium for Geographic Information Sciences
Your support for the Imagery for the Nation program is vital. It's important for Local, Regional, State and Tribal governments to generate letters of support and resolutions for the program and to send electronic copies to NSGIC.