archive-edu.com » EDU » S » SI.EDU

Total: 1278

Choose link from "Titles, links and description words view":

Or switch to "Titles and links view".
  • Transit Satellites | Time and Navigation
    Gone Wrong Soviets Shoot Down an Airliner Reliable Global Navigation Inertial Navigation Charles Stark Draper Developing Inertial Navigation The First Satellite Navigation System Transit Satellites Navigating a Submarine Improving Satellite Navigation Clocks in Space Evolving Solutions Global Positioning System GPS GPS Begins The Satellite Constellation Synchronized Accurate Time Risks to the System International Systems Who Uses Satellite Navigation Military Applications Civilian Applications The Commercial Market Improving Accuracy Looking Ahead Explore More Magellan GPS Test Components Display Screen and Keyboard Seiko Epson Digital Assistant 1997 Prototype GOES Time Receiver Experts Discussing Doppler Tracking Magellan GPS Advertisement Transit Satellites Using Frequency to Find Position The Transit system initially designed to provide precise positioning for the Polaris submarine fleet depended on noting changes in Doppler frequency shift During the 15 minutes it took a Transit satellite to pass from horizon to horizon navigators on a ship or submarine measured the Doppler shift in the satellite s radio transmissions to produce a fix of their position Mathematician Bill Guier and physicist George Weiffenbach told APL Research Center director Frank T McClure about using Doppler tracking for Sputnik McClure suggested that a navigator could use signals from a known satellite position to determine his location anywhere in the world This idea became the basis for Transit The Second Transit Satellite Under Inspection Engineers checking the second Transit satellite Credit Johns Hopkins University Applied Physics Laboratory Experts Discussing Doppler Tracking Mathematician Bill Guier left APL Research Center director Frank T McClure center and physicist George Weiffenbach right Credit Johns Hopkins University Applied Physics Laboratory previous pause resume next Innovations Quartz Oscillators for Transit Satellite Quartz oscillator used to control radio frequency on Transit satellites Learn More See additional innovations How it Works How it Works Transit Satellite Navigation System The Doppler shift of signals from a

    Original URL path: http://timeandnavigation.si.edu/satellite-navigation/reliable-global-navigation/first-satellite-navigation-system/transit-satellites (2016-02-13)
    Open archived version from archive


  • Navigating a Submarine | Time and Navigation
    Improving Accuracy Looking Ahead Explore More Commercial Chip Scale Atomic Clock CSAC The Second Transit Satellite Under Inspection Transit Receiver GPS Block III Satellite Magellan PathMaster Navigation Information System Navigating a Submarine Submarines used radio signals to correct their inertial navigation systems Submarines carry an inertial navigation system which measures the boat s motion and constantly updates position Because it does not rely on radio signals or celestial sightings it allows the boat to navigate while remaining hidden under the surface To maintain accuracy the submarine must periodically update its position using outside navigational radio signals From the 1960s to the 1990s Transit satellites and LORAN shore stations provided those signals GPS has now replaced both Navigating the USS Alabama The Alabama was built with three navigation systems the ship s inertial navigation system SINS a Loran C receiver and a Transit satellite receiver system for correcting the inertial system It has since been fitted with a GPS receiver and the Trident II navigation system Ship s Inertial Navigation System SINS Stable Platform and Housing Assembly The Alabama has three inertial guidance units Manufactured by the Autonetics Marine Systems Division of Rockwell International now Boeing the SINS was installed on the boat in 1983 and removed in 2006 after over 60 patrols Information about the ship s position speed heading and attitude were constantly transmitted from the SINS to the missile fire control system The boat s exact position was required for launching ballistic missiles USS Alabama The USS Alabama was outfitted with a SINS system for navigation Credit U S Navy General Dynamics Electric Boat Sailor aboard the USS Alabama Electronics Technician 1st Class David Schlessinger on board the USS Alabama Credit United States Navy Ship s Inertial Navigation System SINS The components pictured here are just part of

    Original URL path: http://timeandnavigation.si.edu/satellite-navigation/reliable-global-navigation/first-satellite-navigation-system/navigating-a-submarine (2016-02-13)
    Open archived version from archive

  • Improving Satellite Navigation | Time and Navigation
    and Navigation The untold story of getting from here to there Search form Search Navigating at Sea Navigating in the Air Navigating in Space Satellite Navigation Navigation for Everyone Timeline of Innovation Artifacts Learning Resources Multimedia Gallery Research Journal Visit the Exhibition Satellite Navigation Challenges of Satellite Navigation Navigation Gone Wrong Soviets Shoot Down an Airliner Reliable Global Navigation Inertial Navigation Charles Stark Draper Developing Inertial Navigation The First Satellite Navigation System Transit Satellites Navigating a Submarine Improving Satellite Navigation Clocks in Space Evolving Solutions Global Positioning System GPS GPS Begins The Satellite Constellation Synchronized Accurate Time Risks to the System International Systems Who Uses Satellite Navigation Military Applications Civilian Applications The Commercial Market Improving Accuracy Looking Ahead Explore More Lockheed SR 71 Blackbird on Display Supplies Being Dropped by a Cargo Plane Prototype GOES Time Receiver Experts Discussing Doppler Tracking System Maintenance Improving Satellite Navigation Before GPS several satellite systems were developed to provide time and navigation services During the Cold War U S defense planners sought a global navigation system that would be more accurate than the Navy s Transit system and be available at all times Several groups of government and military researchers independently designed different systems to address this need Clocks in Space The development of additional solutions for satellite improvements Evolving Solutions The development of satellite time for civilian use NRL s NTS 2 Team The NTS 2 Development Team at the Naval Research Laboratory Credit Naval Research Laboratory NTS 2 Satellite This illustration shows the important components of the NTS 2 satellite Credit National Air and Space Museum Smithsonian Institution previous pause resume next Navigating at Sea Challenges of Sea Navigation Navigating Without a Clock The Longitude Problem The U S Goes to Sea Navigate at Sea Activity Navigating in the Air Challenges of

    Original URL path: http://timeandnavigation.si.edu/satellite-navigation/reliable-global-navigation/improving-satellite-navigation (2016-02-13)
    Open archived version from archive

  • Clocks in Space | Time and Navigation
    System International Systems Who Uses Satellite Navigation Military Applications Civilian Applications The Commercial Market Improving Accuracy Looking Ahead Explore More WPI Precision Personnel Locator PPL NRL s NTS 2 Team GPS Constellation Trimble ScoutMaster 1997 Technicians Working on the NTS 2 Satellite Clocks in Space Atomic Clocks for Space The Naval Research Laboratory in the 1970s investigated whether atomic clocks would work in space in the TIMATION Program Like John Harrison in the 18th century atomic clockmakers had to find ways to miniaturize clocks without sacrificing stability in a new environment These clocks are based on the elements rubidium and cesium Rubidium clocks are smaller and less costly but slightly less accurate than cesium clocks Navigation Technology Satellite 2 Engineering Test Model The Navigation Technology Satellite 2 NTS 2 was launched in 1977 to test new navigation techniques The two cesium atomic clocks on board helped to show that satellite navigation based on precise timing was possible This engineering model was used at the Naval Research Laboratory for testing the satellite before launch Technicians Working on the NTS 2 Satellite Charlie Buhler left Al Jacoby middle and Roy Harding right of NRL install thermal blankets on the NTS 2 qualification model Credit Naval Research Laboratory NTS 2 Satellite This illustration shows the important components of the NTS 2 satellite Credit National Air and Space Museum Smithsonian Institution Rubidium Frequency Standard This atomic clock was built for the first GPS satellites in the late 1970s Credit National Air and Space Museum Smithsonian Institution Cesium Brassboard Frequency Standard A cesium clock like this was tested on the NTS 2 satellite to see if clocks could keep accurate time in space Credit National Museum of American History Smithsonian Institution previous pause resume next Innovations NRL Rubidium Frequency Standard A rubidium clock like this

    Original URL path: http://timeandnavigation.si.edu/satellite-navigation/reliable-global-navigation/improving-satellite-navigation/clocks-space (2016-02-13)
    Open archived version from archive

  • Evolving Solutions | Time and Navigation
    The Commercial Market Improving Accuracy Looking Ahead Explore More Commercial Chip Scale Atomic Clock CSAC Ship s Inertial Navigation System SINS Magellan GPS Advertisement Honeywell RQ 16 T Hawk Micro Air Vehicle MAV Engineer Working on a SECOR Satellite Evolving Solutions TIMATION TIM E NAVIG ATION Developed by The Naval Research Laboratory NRL When 1964 Purpose To test whether accurate time signals sent from a satellite could provide a worldwide navigation system How it worked TIMATION satellites carried very stable time references These were used to test the concept of measuring position and distance to satellites based on the travel time of radio signals TIMATION satellites carried very stable time references These were used to test the concept of measuring position and distance to satellites based on the travel time of radio signals Plan 621B Developed by Air Force Space and Missile Systems Organization and The Aerospace Corporation When Reached the testing stage in the late 1960s Purpose To help identify the locations of aircraft How it worked Called for satellites to transmit a jam resistant signal to aircraft which would enable navigators to determine their latitude longitude and altitude SECOR Sequential Collation of Range Developed by U S Army When 1964 to 1969 Purpose For mapping research to find exact positions of remote places far from the continents especially Pacific islands How it worked The satellites worked in tandem with four portable ground stations The Army successfully launched nine SECOR satellites Civilian Satellite Time The U S Department of Commerce established a precise time service based on satellite signals in 1974 The National Bureau of Standards provided the time The electric power industry found the time service useful for synchronizing AC generators to move electricity from one part of the power grid to another The signals were transmitted by

    Original URL path: http://timeandnavigation.si.edu/satellite-navigation/reliable-global-navigation/improving-satellite-navigation/evolving-solutions (2016-02-13)
    Open archived version from archive

  • GPS Begins | Time and Navigation
    story of getting from here to there Search form Search Navigating at Sea Navigating in the Air Navigating in Space Satellite Navigation Navigation for Everyone Timeline of Innovation Artifacts Learning Resources Multimedia Gallery Research Journal Visit the Exhibition Satellite Navigation Challenges of Satellite Navigation Navigation Gone Wrong Soviets Shoot Down an Airliner Reliable Global Navigation Inertial Navigation Charles Stark Draper Developing Inertial Navigation The First Satellite Navigation System Transit Satellites Navigating a Submarine Improving Satellite Navigation Clocks in Space Evolving Solutions Global Positioning System GPS GPS Begins The Satellite Constellation Synchronized Accurate Time Risks to the System International Systems Who Uses Satellite Navigation Military Applications Civilian Applications The Commercial Market Improving Accuracy Looking Ahead Explore More The Joint Precision Airdrop System JPADS Magellan 2000 XL 1996 Juno Spacecraft Approaching Venus The Blue Force Tracker System SINS Typewriter GPS Begins GPS required the development testing and refinement of receivers atomic clocks and other components Developing GPS components began in 1973 when the Joint Program Office was established under the Air Force to run and maintain the system As designs evolved positioning and navigation accuracy improved GPS resulted from a combination of parallel efforts in the 1960s Defense Department planners decided to combine the best technologies from these various programs the Navy s Transit and TIMATION the Air Force s 621B and the Army s SECOR into one At a meeting over Labor Day weekend in 1973 they created the Defense Navigation Satellite System It was later renamed the NAVSTAR Global Positioning System now generally known as GPS Planning the Creation of the Global Positioning System Engineers discussing the Global Positioning System Credit The Aerospace Corporation Navigating at Sea Challenges of Sea Navigation Navigating Without a Clock The Longitude Problem The U S Goes to Sea Navigate at Sea Activity Navigating in

    Original URL path: http://timeandnavigation.si.edu/satellite-navigation/gps/gps-begins (2016-02-13)
    Open archived version from archive

  • The Satellite Constellation | Time and Navigation
    of Satellite Navigation Navigation Gone Wrong Soviets Shoot Down an Airliner Reliable Global Navigation Inertial Navigation Charles Stark Draper Developing Inertial Navigation The First Satellite Navigation System Transit Satellites Navigating a Submarine Improving Satellite Navigation Clocks in Space Evolving Solutions Global Positioning System GPS GPS Begins The Satellite Constellation Synchronized Accurate Time Risks to the System International Systems Who Uses Satellite Navigation Military Applications Civilian Applications The Commercial Market Improving Accuracy Looking Ahead Explore More NTS 2 Satellite Quartz Resonator for Transit Satellites Garmin eTrex 2007 Lockheed SR 71 Blackbird in Flight GPS Accuracy With and Without Selective Availability The Satellite Constellation Rockwell International now a division of Boeing was contracted to build GPS satellites beginning in 1974 By 1986 18 had been launched into orbit making the system usable for many applications The full suite of 24 satellites needed for global coverage was in orbit by early 1995 Beginning in the 1990s Lockheed Martin built new generations of GPS satellites More than 30 GPS satellites were operational after 2010 GPS satellites are positioned in precise circular orbits 18 000 kilometers 11 000 miles above the Earth They orbit once every 12 hours GPS Constellation GPS satellites are positioned in precise circular orbits 18 000 kilometers 11 000 miles above the Earth They orbit once every 12 hours Credit National Air and Space Museum Smithsonian Institution X Set Test Receivers Magnavox X Set GPS receiver Credit Vito Calbi GPS Receiver The first military GPS five channel receiver weighing 270 pounds Credit Rockwell Collins previous pause resume next Innovations GPS Receiver The first military GPS five channel receiver weighing 270 pounds Learn More See additional innovations How it Works How it Works How Does GPS Work From maintaining infrastructure transporting goods delivering services or just meeting friends people often use technology

    Original URL path: http://timeandnavigation.si.edu/satellite-navigation/gps/satellite-constellation (2016-02-13)
    Open archived version from archive

  • Synchronized Accurate Time | Time and Navigation
    Draper Developing Inertial Navigation The First Satellite Navigation System Transit Satellites Navigating a Submarine Improving Satellite Navigation Clocks in Space Evolving Solutions Global Positioning System GPS GPS Begins The Satellite Constellation Synchronized Accurate Time Risks to the System International Systems Who Uses Satellite Navigation Military Applications Civilian Applications The Commercial Market Improving Accuracy Looking Ahead Explore More Joint Precision Air Drop System JPADS Parachute and Guidance Unit Garmin GPS 45XL 1994 Transit Receiver Blue Force Tracker System GPS Accuracy With Selective Availability Synchronized Accurate Time GPS requires precise clocks to provide astounding positional accuracy Atomic clocks in GPS satellites keep time to within three nanoseconds three billionths of a second Position accuracy depends on the receiver Most handheld GPS receivers are accurate to about 10 to 20 meters 33 to 66 feet GPS Accuracy Both military and civilian users can obtain higher accuracy by using a second GPS unit at a fixed nearby location a method called Differential GPS In this way positions can be determined with an accuracy better than 1 centimeter less than half an inch For military users additional encrypted signals can provide high accuracy Synchronizing GPS All GPS satellites must transmit their data signals at the exact same time so precise synchronization is essential Their signals are monitored constantly and adjusted as needed The GPS Operations Center at Schriever Air Force Base in Colorado Springs Colorado controls the constellation of satellites that provides navigation data to military and civilian users worldwide NIST 7 Cesium Frequency Standard In the 1990s the NIST 7 was the most accurate clock in the country and helped keep the GPS clocks synchronized Credit National Air and Space Museum Smithsonian Institution Innovations U S Naval Observatory Alternate Master Clock The U S Naval Observatory Alternate Master Clock at Schriever Air Force Base

    Original URL path: http://timeandnavigation.si.edu/satellite-navigation/gps/synchronized-accurate-time (2016-02-13)
    Open archived version from archive