GPS - Aircraft Navigation

Questions / Comments

THIS DAY IN AVIATION November 20 1919 — The first municipal airport in the United States opens in Tucson, Arizona and is still in use today.

THIS DAY IN AVIATION November 20 1943 — United States troops invade Makin and Tarawa in the Gilbert Islands

THIS DAY IN AVIATION November 20 1953 — The first man to exceed Mach 2 is American test pilot Scott Crossfield in a Douglas D-558-2 “Skyrocket.”

THIS DAY IN AVIATION November 20 1957 — The Vertol 105 twin-turbine powered helicopter, using two Lycoming T-53B's, flies for the first time

THIS DAY IN AVIATION November 20 1959 — Discoverer VIII satellite is launched into orbit from Cape Canaveral, Florida.

THIS DAY IN AVIATION November 20 1963 — The USAF accepts its first two McDonnell Douglas F-4C “Phantom II” jet fighters.

Questions / Comments

November 2017 Chap 5 Quiz FLIGHTLINE 5 6 Chapter 5 SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY 5 6 Chapter 5 Military Developments Separate Air Force Wartime Advances 7 Jet Propulsion “Vengeance Weapons” Helicopters 8 Berlin Airlift 9 Korean War Lessons Learned 10 Chap 5 Quiz FLIGHTLINE 11   12 13 Commercial Aviation General Aviation 14 Aviation R & D 15 Vietnam War Phase 1 and 2 16 Phase 3 and 4 17 Chap 5 TEST 18 19 20 21 22 NO SCHOOL 23 THANKSGIVING 24 25 26 27 Chapter 6 Advances in Aeronautics 28 29 Chap 6 TEST 30 1 2

AVIATION ACES 3A 3A Jelly Fam Ari Ethan WTR Scorpion Akeem Pilots (A – 90 & above) 3A Co-Pilots (B – 80 – 89) Jelly Fam Ethan Scorpion Rated Rocket K-Dogg Eagle 1 Ari WTR Akeem Blackbird Michael Bubba Frenchie Rubber Ducky Fireball Falcon Black Eagle High Shooter (100)

Questions / Comments

Global Positioning System (GPS)

Global Positioning System (GPS) Cloud of 24 GPS satellites orbit the Earth Satellite positions are accurately known GPS device receives satellite signal with ‘time-sent’ information Device calculates distance to satellite Intersection point of multiple satellites defines device location Image source: http://scign.jpl.nasa.gov/learn/gps2.htm A global positioning system utilizes multiple satellites that orbit the Earth. The triangulation of the satellites is based on extremely precise timing of radio waves that are received from the satellites. Since the satellites are not stationary but moving through space at thousands of miles per hour, the radio waves are slow. They bend and bounce their way from satellite to receiver. With the challenges that arise from the satellites orbiting the Earth, it is easier to examine how the GPS works in smaller bits. How does GPS really work, how is the accuracy challenged and maintained, and how are technical and engineering techniques used to overcome those challenges to make GPS the most readily available, accurate, and truly global navigational system available?

GPS Orbital Configuration 24 satellites 20,000 km (Approximately 12,500 mi) above Earth Orbits take 12 hours Cover entire Earth

GEO Caching www.geocaching.com

GPS – Aircraft Navigation You are an aircraft pilot who must navigate a course from “waypoint” to “waypoint” in sequence and locate all items. Your team will plot a course of 5 “waypoint items” and document their location with lat/long coordinates. You will create a map of your routes in sequence. (in Powerpoint and take pictures of your items/location with coordinates) Selective Availability was the military degradation of the GPS accuracy for defense purposes. More information is available at the National Executive Committee for Space-Based PNT website: http://pnt.gov/public/sa/ The PRC and ephemeris signals from four satellites should provide an absolutely accurate position to the precision of the atomic clock on the satellite. The key word is “should” as there are many problems associated with timing the signal’s travel time. Remember even a thousandth of a second is a huge error!   Problems include the reduction in the speed of light as it enters the atmosphere (error to greater distance), signals that reflect off of multiple objects and create echoes that arrive at different times, purposeful errors, and even atomic clock errors. We can correct for the atmospheric problems by using more advanced technology. If the receiver can monitor dual frequencies, then it can compare the amount of variation between a low-frequency (slowed more) and a high-frequency (slowed less) signal to deduce the error and correct for it. The GPS system broadcasts on two different carrier frequencies called L1 and L2. Unfortunately, this requires a very sophisticated receiver. Only the military has access to the L2 carrier channel. The other option is to build in atmospheric models so that “typical” corrections can be made to all incoming signals. Receivers can deal with the multi-path errors by employing signal rejection analysis software. The basic principle is that the first signal to arrive will have traveled along the shortest route and thus any signal that arrives later is most likely an echo and should be ignored. Before May 1, 2000, the government purposely degraded the timing data of the satellite’s clock by adding noise to the signal. They may also have introduced slight inaccuracies to the ephemeris data. Military GPS receivers made use of a decryption key to obtain the full accuracy information. This Selective Availability (SA) was disabled, which improved the accuracy of GPS positions by a factor of 10. All of these errors combined introduced errors of about 10 meters. With SA active, this led to errors of hundreds of feet. Without SA the basic GPS receiver is capable of measuring positions to within 30 or 50 feet. This is accurate enough for an aircraft approaching a runway, but unfortunately it isn’t accurate enough to land the aircraft on the centerline of the runway.

GPS – Aircraft Navigation You will be provided a entry log to record all items and their respective lat/long coordinates Take picture of item in its location Teams will exchange coordinate charts with item description. Final report will be a Powerpoint with pictures of waypoint locations and items. Google earth to create map. Selective Availability was the military degradation of the GPS accuracy for defense purposes. More information is available at the National Executive Committee for Space-Based PNT website: http://pnt.gov/public/sa/ The PRC and ephemeris signals from four satellites should provide an absolutely accurate position to the precision of the atomic clock on the satellite. The key word is “should” as there are many problems associated with timing the signal’s travel time. Remember even a thousandth of a second is a huge error!   Problems include the reduction in the speed of light as it enters the atmosphere (error to greater distance), signals that reflect off of multiple objects and create echoes that arrive at different times, purposeful errors, and even atomic clock errors. We can correct for the atmospheric problems by using more advanced technology. If the receiver can monitor dual frequencies, then it can compare the amount of variation between a low-frequency (slowed more) and a high-frequency (slowed less) signal to deduce the error and correct for it. The GPS system broadcasts on two different carrier frequencies called L1 and L2. Unfortunately, this requires a very sophisticated receiver. Only the military has access to the L2 carrier channel. The other option is to build in atmospheric models so that “typical” corrections can be made to all incoming signals. Receivers can deal with the multi-path errors by employing signal rejection analysis software. The basic principle is that the first signal to arrive will have traveled along the shortest route and thus any signal that arrives later is most likely an echo and should be ignored. Before May 1, 2000, the government purposely degraded the timing data of the satellite’s clock by adding noise to the signal. They may also have introduced slight inaccuracies to the ephemeris data. Military GPS receivers made use of a decryption key to obtain the full accuracy information. This Selective Availability (SA) was disabled, which improved the accuracy of GPS positions by a factor of 10. All of these errors combined introduced errors of about 10 meters. With SA active, this led to errors of hundreds of feet. Without SA the basic GPS receiver is capable of measuring positions to within 30 or 50 feet. This is accurate enough for an aircraft approaching a runway, but unfortunately it isn’t accurate enough to land the aircraft on the centerline of the runway.

LAT / LONG FORMAT

How to Record Data

GEO CACHE MAPPING GOOGLE EARTH

GARMIN – eTrex GPS

Questions / Comments