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Selective Availability Anti-spoofing Module
A Selective Availability Anti-spoofing Module (SAASM) used by military Global Positioning System receivers to allow decryption of precision GPS observations, while the accuracy of civilian GPS receivers may be reduced by the United States military through Selective Availability The error analysis for the Global Positioning System is important for understanding how GPS works, and for knowing what magnitude of error should be expected. The GPS makes corrections for receiver clock errors and other effects but there are sti ... (SA) and anti-spoofing (AS). However, on May 1, 2000 it was announced that SA was being discontinued, along with a United States Presidential Directive that no future GPS programs will include it. Before the advent of L2C, AS was meant to prevent access to dual-frequency observations to civilian users. SAASM allows satellite authentication, over-the-air rekeying, and contingency recovery. Those features are not available with the similar, but older, PPS-SM ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Positioning System
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite systems (GNSS) that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. It does not require the user to transmit any data, and operates independently of any telephonic or Internet reception, though these technologies can enhance the usefulness of the GPS positioning information. It provides critical positioning capabilities to military, civil, and commercial users around the world. Although the United States government created, controls and maintains the GPS system, it is freely accessible to anyone with a GPS receiver. The GPS project was started by the U.S. Department of Defense in 1973. The first prototype spacecraft wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GPS Signals
GPS signals are broadcast by Global Positioning System satellites to enable satellite navigation. Receivers on or near the Earth's surface can determine location, time, and velocity using this information. The GPS satellite constellation is operated by the 2nd Space Operations Squadron (2SOPS) of Space Delta 8, United States Space Force. GPS signals include ranging signals, used to measure the distance to the satellite, and navigation messages. The navigation messages include ''ephemeris'' data, used to calculate the position of each satellite in orbit, and information about the time and status of the entire satellite constellation, called the ''almanac''. There are four GPS signal specifications designed for civilian use. In order of date of introduction, these are: L1 C/A, L2C, L5 and L1C. L1 C/A is also called the ''legacy signal'' and is broadcast by all currently operational satellites. L2C, L5 and L1C are ''modernized signals,'' and only broadcast by newer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Military
The United States Armed Forces are the military forces of the United States. The armed forces consists of six service branches: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. The president of the United States is the commander-in-chief of the armed forces and forms military policy with the Department of Defense (DoD) and Department of Homeland Security (DHS), both federal executive departments, acting as the principal organs by which military policy is carried out. All six armed services are among the eight uniformed services of the United States. From their inception during the American Revolutionary War, the U.S. Armed Forces have played a decisive role in the history of the United States. They helped forge a sense of national unity and identity through victories in the First Barbary War and the Second Barbary War. They played a critical role in the American Civil War, keeping the Confederacy from seceding from the republic and preservin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selective Availability
The error analysis for the Global Positioning System is important for understanding how GPS works, and for knowing what magnitude of error should be expected. The GPS makes corrections for receiver clock errors and other effects but there are still residual errors which are not corrected. GPS receiver position is computed based on data received from the satellites. Errors depend on geometric dilution of precision and the sources listed in the table below. Overview User equivalent range errors (UERE) are shown in the table. There is also a numerical error with an estimated value, \ \sigma_ , of about . The standard deviations, \ \sigma_R, for the coarse/acquisition (C/A) and precise codes are also shown in the table. These standard deviations are computed by taking the square root of the sum of the squares of the individual components (i.e., RSS for root sum squares). To get the standard deviation of receiver position estimate, these range errors must be multiplied by the a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GPS Anti-spoofing
The error analysis for the Global Positioning System is important for understanding how GPS works, and for knowing what magnitude of error should be expected. The GPS makes corrections for receiver clock errors and other effects but there are still residual errors which are not corrected. GPS receiver position is computed based on data received from the satellites. Errors depend on geometric dilution of precision and the sources listed in the table below. Overview User equivalent range errors (UERE) are shown in the table. There is also a numerical error with an estimated value, \ \sigma_ , of about . The standard deviations, \ \sigma_R, for the coarse/acquisition (C/A) and precise codes are also shown in the table. These standard deviations are computed by taking the square root of the sum of the squares of the individual components (i.e., RSS for root sum squares). To get the standard deviation of receiver position estimate, these range errors must be multiplied by the app ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GPS Modernization
GPS Block III (previously Block IIIA) consists of the first ten GPS III satellites, which will be used to keep the Navstar Global Positioning System operational. Lockheed Martin designed, developed and manufactured the GPS III Non-Flight Satellite Testbed (GNST) and all ten Block III satellites. The first satellite in the series was launched in December 2018. The tenth and final GPS Block III launch is projected in 2023. History The United States' Global Positioning System (GPS) reached Full Operational Capability on 17 July 1995, completing its original design goals. Advances in technology and new demands on the existing system led to the effort to modernize the GPS system. In 2000, the U.S. Congress authorized the effort, referred to as GPS III. The project involves new ground stations and new satellites, with additional navigation signals for both civilian and military users, and aims to improve the accuracy and availability for all users. Raytheon was awarded the Nex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Defense Advanced GPS Receiver
The AN/PSN-13 Defense Advanced GPS Receiver (DAGR; colloquially, "dagger") is a handheld GPS receiver used by the United States Department of Defense and select foreign military services. It is a military-grade, dual-frequency receiver, and has the security hardware necessary to decode the encrypted P(Y)-code GPS signals. Manufactured by Rockwell Collins, the DAGR entered production in March 2004, with the 40,000th unit delivered in September 2005. It was estimated by the news source ''Defense Industry Daily'' that, by the end of 2006, the USA and various allies around the world had issued almost $300 million worth of DAGR contracts, and ordered almost 125,000 units. The DAGR replaced the Precision Lightweight GPS Receiver (PLGR), which was first fielded in 1994. Rockwell Collins also manufactures a GPS receiver known as the "Polaris Guide", that looks like a DAGR, but uses only the civilian C/A code signals. These units are labelled as "SPS", for " Standard Positioning Service ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precision Lightweight GPS Receiver
The AN/PSN-11 Precision Lightweight GPS Receiver (PLGR, colloquially "plugger") is a ruggedized, hand-held, single-frequency GPS receiver fielded by the United States Armed Forces. It incorporates the Precise Positioning Service — Security Module (PPS-SM) to access the encrypted P(Y)-code GPS signal. Introduced in January 1990, and extensively fielded until 2004 when it was replaced by its successor, the Defense Advanced GPS Receiver (DAGR). In that time period more than 165,000 PLGRs were procured worldwide, and despite being superseded by the DAGR, large numbers remain in unit inventories and it continues to be the most widely used GPS receiver in the United States military. The PLGR measures 9.5 by 4.1 by 2.6 inches and weighs with batteries. It was originally delivered to the United States military with a six-year warranty; however, this was extended to ten years in June 2000. Versions *''AN/PSN-11'' — NSN 5825-01-374-6643, an early version (tan case) *''AN/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
