Скачать презентацию GPS GNSS Global Positioning System Global Navigation Satellite Скачать презентацию GPS GNSS Global Positioning System Global Navigation Satellite

5f88a7dd689ebed2fa5174736e0d00ce.ppt

  • Количество слайдов: 64

GPS GNSS (Global Positioning System) (Global Navigation Satellite System) GPS GNSS (Global Positioning System) (Global Navigation Satellite System)

Basic Concept • 32+/- Satellites orbiting the earth +/- 20, 000 km (12, 600 Basic Concept • 32+/- Satellites orbiting the earth +/- 20, 000 km (12, 600 miles or 11, 000 Nm) up 6 Paths, sun-synchronous, each satellite orbits earth 2 x/day Operational in 1993 (“NAVSTAR”), 32 Satellites max. (24 min. ) Managed by the Department of Defense • Satellites communicate with Receivers • Receivers determines distance (signal delay) • Distance from multiple satellites determines location Ø Ø Ø v Requires very precise clocks Satellites use atomic clocks (0. 00003 seconds) Receiver’s clock corrected by satellites More satellites, widely spaced provides better results Longer duration of data capture provides better results One of a variety of GNSS (Global Navigation Satellite Systems)

Accuracy (Potential) Horizontal location (meters) Recreational/Pocket Unit Mapping Grade (Geo. Exp 3) Surveyor Grade Accuracy (Potential) Horizontal location (meters) Recreational/Pocket Unit Mapping Grade (Geo. Exp 3) Surveyor Grade Smart phones…. +/RT-DGPS* 5 -20 2 -5 5 -20 1 1 -100? DGPS 2 -5 0. 5** $ 100 -500 4, 500 40, 000 * w/external add-on Radio Beacon unit ** w/10 minutes of data & Post-Processing: with 30 minutes of data with 45 minutes of data with 48+ hours of data 0. 3 0. 1 0. 01 (centimeter accuracy) 0. 001 (millimeter accuracy? 5 m : 20, 000 km ~ 1/10 of the width of a grain of rice from the top of the Empire State Building (381 m)… (. 1 mm : 381 m) (Vertical Accuracy typically half as good as horizontal) )

What you get for your $ • • • • WAAS compatible Ability to What you get for your $ • • • • WAAS compatible Ability to download data to a PC Barometric altimeter (more accurate than GPS for altitude, if calibrated) Waterproof - backlight display - battery life - screen size - split screen zoom More memory - storage of points, tracks, areas, offsets Store/view base maps &/or charts - streets, hydro Accessories: remote antennas, RT-DGPS, Laser Range Finder Ability to connect to PDAs or Laptops (real time GPS mapping) Differential correction (RT-DGPS and/or post processing) Ability to enter attribute data (features) Ability to update / append to existing features and/or data files Vehicle navigation Electronic compass Vertical profiles of tracks Alarms (anchor drift, arrival, off-course) Fish locators, tide charts, calendars, celestial information

Applications • Military (Do. D) – civilian uses now exceed military • A ‘Free Applications • Military (Do. D) – civilian uses now exceed military • A ‘Free Utility’ maintained by the Air Force • Space Travel (NASA) • Survey, Mapping & GIS • Resource and Asset Management Environmental & Forestry Mining, Oil & Gas • Agriculture • Utilities & Construction • Transportation • Vehicle Security (Fleet Management) • Public Safety Emergency Management, Search & Rescue Crime Prevention • Timing & Synchronization (banking, telecommunications) • LBS - Location Based Services (cell phones, wireless web) Solar GPS Cattle Herder (noise or electric shock) Precision Construction & Agriculture

Other Applications… • On Board Vehicle Navigation Systems • Vehicle Tracking Systems (beyond fleet Other Applications… • On Board Vehicle Navigation Systems • Vehicle Tracking Systems (beyond fleet management) - Rental Car Companies - GPS-measured Tolls – variable taxation (UK) - Family/Friends vehicle location - Crime: Stolen cars; Criminal tracking - Accident notification systems - ‘Pay-as-you-drive’ insurance plans • Child/Senior/Pet Safety Tracking Systems • Parole, Probation Tacking Systems • Package/Asset Tracking Systems • Bridge structural monitoring • Sports and Broadcasting (Skiers, NASCAR, Sailboat races) • Golf Courses (distance to next hole…) • Geo-Caching (GPS scavenger/treasure hunts) • Beer Bottle GPS • etc, Golf Courses Parole Anklet Car Navigation

Other Applications… Tracking Systems - Pet Collar ($300 + $20/month) - Teddy Bears, Backpacks Other Applications… Tracking Systems - Pet Collar ($300 + $20/month) - Teddy Bears, Backpacks - Implants… Xega injectable GPS chip ($4, 000 + $350/month) Mexico (requires additional wearable accessory) Nano GPS tracker ($200 + $45/month), panic button, for people or nativity scenes… Pet collars Web or cell connection Virtual/Geo-Fence GTX Ambulator (Alzheimer’s GPS Shoes) (tracking and geo-fence) Garmin Astro Pet Tracker (communicates with base unit)

Other Applications… Mobile Phones • E 911, (Enhanced 911) passed into law in 1999… Other Applications… Mobile Phones • E 911, (Enhanced 911) passed into law in 1999… (same year as first GPS in cell phones) - Either GPS or Network (tower) based – or both - So that They could find you, not so you could know where you were… - Over 75% of 911 calls now come from mobile phones (not so good indoors…) • The majority of all GPS receivers ever built have been for Cell Phones • Most in the last 3 years • 1 billion + phones have GPS Smart Phones • Almost 100% are now GPS enabled (if you turn it On) • Cost is now less than $5 per phone • Many are augmented GPS systems (A-GPS or GPS +) • Cell towers (closer and faster than satellites) • Wi-fi • Inertial movement units (inertial navigation systems) • GPS + WAAS, EGNOS, MSAS, Galileo, GLONASS…

Other Applications… Mobile Phones Maps Traffic Find… Directions (car or service) Geotagged photos Friend Other Applications… Mobile Phones Maps Traffic Find… Directions (car or service) Geotagged photos Friend Finder Car locator Hiking Google Maps Astronomy (Consumer or Resource? ) Golf GPS Find lost (or stolen) phone Here I Am (connect with other users, friends in your contacts) Geo-Tag Photos Simulators More GPS units in smart phones than all other GPS receivers combined… Transit Weather Not strictly GPS… GPS (satellites, if signal is available) Cell tower triangulation and/or signal strength + built in digital compass Virtual Sky

Other Applications… Timing and Synchronization • ATM & Cellular networks • Seismic activity • Other Applications… Timing and Synchronization • ATM & Cellular networks • Seismic activity • Camera synchronization Academics • • Study areas, sample sites Animal tracking (goats, birds, turtles) Survey documentation Photo geo-tagging • Accuracy improving -Surveying world’s largest salt flat (Bolivia), readings were 5 mm less at the end of the day…

Advantages / Disadvantages… ADVANTAGES • Mobility • Global coverage • Weather independent • Day Advantages / Disadvantages… ADVANTAGES • Mobility • Global coverage • Weather independent • Day or Night • Accuracy DISADVANTAGES • Requires clear view of sky • Ionospheric influences • Multi-path - buildings, canyons, trees - large, wet leaves - large flat buildings - chain link fences

GPS Satellites visible from location at 45˚ N Black = visible satellites, Red = GPS Satellites visible from location at 45˚ N Black = visible satellites, Red = not visible, Green = sight lines Graphic (Constellations. GPS. gif) from Wikimedia Commons (commons. wikimedia. org)

Trilateration… 3 Sec 5 Sec X? Trilateration… 3 Sec 5 Sec X?

3 Sec 5 Sec X 4 Sec 3 Sec 5 Sec X 4 Sec

Triangle of Error X? Triangle of Error X?

15º 15º

GDOP = Geometric Dilution of Precision Estimate of satellite conditions for a given location GDOP = Geometric Dilution of Precision Estimate of satellite conditions for a given location & time Given in distance units (meters or feet) Ideal GDOP: One Satellite directly overhead w/an abundance of additional satellites spaced evenly around the sky Poor GDOP: Satellites clustered

PDOP vs. GDOP PDOP = Position Dilution of Precision (amount of error) “Good” is PDOP vs. GDOP PDOP = Position Dilution of Precision (amount of error) “Good” is from 4 – 6 (< 4 is excellent, > 8 poor) Can be used as a tolerance setting for acceptability of signal quality (a “PDOP mask” or filter) GDOP = Geometric Dilution of Precision Estimate of satellite conditions for a given location & time Sometimes given in distance units (meters or feet) PDOP * GDOP = Overall estimate of accuracy (distance) (PDOP of 4) * (GDOP of 30’) = (Accuracy of +/- 120’) PDOP & GDOP often used interchangeably Also: HDOP, VDOP, TDOP, RDOP… (horizontal, vertical, time, relative) In all cases, smaller is better

Masks: PDOP, Elevation, SNR Ability to control the quality of the data accepted at Masks: PDOP, Elevation, SNR Ability to control the quality of the data accepted at the time of data collection (unacceptable readings are filtered out) PDOP Mask: Allows the recording of positions only when there is acceptable satellite geometry. Typically considers both quantity and quality of satellites (e. g. , 4 satellites with good precision, or 6 with reasonable precision, or 8 with average precision) Elevation Mask: Sets minimum elevation above horizon for satellites to be used. The lower on the horizon a satellite is the more atmosphere the signal must pass through, thus the greater the potential for signal diffraction (inaccurate estimations of time/distance), as well as greater chance of multi-path errors. Also, with Differential Correction, insures that all satellites used are visible to base station as well as the field receiver. SNR (Signal to Noise Ratio) Mask: (higher is better, stronger signal) Filters out signals with excessive noise, using only those satellites with low noise (more accurate). SNR ranges from 0 -35; 10 -15 is typical, less than 5 is generally considered unusable.

Sources of Error Typical amount of Error (per Satellite) Beyond quality of equipment/size of Sources of Error Typical amount of Error (per Satellite) Beyond quality of equipment/size of antenna, etc. • Satellite Atomic Clock Errors (corrected periodically) 1. 5 m • Satellite Orbit (Position) Errors (corrected periodically) 2. 5 m • Earth’s ionosphere (charged particles) 5. 0 m • Earth’s troposphere (moisture) 0. 5 m • Receiver Noise (local conditions, radio interference) 0. 3 m • Multipath Errors (bounce off buildings, etc. ) 0. 6 + • Local Weather (moisture in air, lightning)* • Poor Satellite Geometry (GDOP) • Receiver Clock Errors (corrected by 4 th + Satellites) • Visual obstructions (line of sight)… User errors… * Moisture in tree canopy a bigger deal than in the air…

Sources of Error Typical amount of Error (per Satellite) Beyond quality of equipment/size of Sources of Error Typical amount of Error (per Satellite) Beyond quality of equipment/size of antenna, etc. • Satellite Atomic Clock Errors (corrected periodically) 1. 5 m • Satellite Orbit (Position) Errors (corrected periodically) 2. 5 m • Earth’s ionosphere (charged particles) 5. 0 m • Earth’s troposphere (moisture) 0. 5 m • Receiver Noise (local conditions, radio interference)* 0. 3 m • Multipath Errors (bounce off buildings, etc. )* 0. 6 + • Local Weather (moisture in air, lightning) • Poor Satellite Geometry (GDOP) • Receiver Clock Errors (corrected by 4 th + Satellites)* • Visual obstructions (line of sight)… User errors * Sources of error that are NOT improved by DGPS

Selective Availability (GPS) Intentional degradation of signal quality by Do. D for security reasons. Selective Availability (GPS) Intentional degradation of signal quality by Do. D for security reasons. Spawned numerous ‘work-around’ technologies Turned off in May, 2000, recognizing civilian need for better quality GPS signal (while reserving the option to reinstate it should the need arise). New satellites will not have this ability (as of 9/07)…

Differential Correction Compare GPS data file from Rover file (handheld unit) with a data Differential Correction Compare GPS data file from Rover file (handheld unit) with a data file from a Base Station (at a known coordinate) for the exact same time period. Relies on the fact that receivers located relatively close together, will record similar errors from the same constellation of satellites. Uses the apparent “error” of the base station file to correct the corresponding error of the Rover file.

GPS (Estimated) Location Actual (Known) Position GPS Receiver Estimated Location Differentially Corrected Estimated Position GPS (Estimated) Location Actual (Known) Position GPS Receiver Estimated Location Differentially Corrected Estimated Position 10 m Base Station (w/known coordinates) Receiver (unknown Location)

Differential Correction • Can improve accuracy by up to 20 m. (50 -90%) • Differential Correction • Can improve accuracy by up to 20 m. (50 -90%) • Requires local Base Station (w/in 100 miles) • Requires “post-processing” (back in the lab) OR can be done on-the-fly using Real-Time DGPS • Need better data – longer recording period, better GDOP • More Base Stations near coasts (navigation) • No effect on multi-path and/or receiver errors But we’re not going to do that…

WAAS (Wide Area Augmentation System) • On-the-fly generalized version of Differential Correction • Developed WAAS (Wide Area Augmentation System) • On-the-fly generalized version of Differential Correction • Developed by FAA and DOT (airport safety, precision landings) WAAS only works in North America (there is also EGNOS in Europe, MSAS in Japan/Asia) • Base station data is aggregated and sent to WAAS satellites (Multiple Geostationary satellites, east coast and west coast) • Corrections are sent out from WAAS satellites • WAAS-compatible GPS receivers use correction to improve accuracy • WAAS satellites are equatorial, so WAAS works less well the further north you go (or if your location has obstructions to the south) • WWU’s Garmin GPSmap 60 units are WAAS-compatible • Using WAAS drains the battery faster (can be turned off)

CDGNSS (Carrier-phase Differential GNSS) • • Real-time Differential Correction Dense reference network (3/1, 000 CDGNSS (Carrier-phase Differential GNSS) • • Real-time Differential Correction Dense reference network (3/1, 000 km 2) 10 cm accuracy Vehicle navigation augmentation – Precise in-lane location of your car and other nearby cars… – Automated driving (self-driving cars)… • …coming soon… to urban areas http: //digital. gpsworld. com/Sept 2016

Sources of Error Typical amount of Error (per Satellite) Beyond quality of equipment/size of Sources of Error Typical amount of Error (per Satellite) Beyond quality of equipment/size of antenna, etc. • Satellite Atomic Clock Errors (corrected periodically) 1. 5 m • Satellite Orbit (Position) Errors (Ephemeris error) (corrected periodically) 2. 5 m • Earth’s ionosphere (charged particles) 5. 0 m • Earth’s troposphere (temperature, pressure, humidity) 0. 5 m • Receiver Noise (local conditions, radio interference) 0. 3 m • Multipath Errors (bounce off buildings, etc. ) 0. 6 + • Local Weather (moisture in air, lightning)* • Poor Satellite Geometry (GDOP) • Receiver Clock Errors (corrected by 4 th + Satellites) * Moisture in tree canopy a bigger deal than in the air…

Accuracy… Original (civilian) GPS, w/Selective Availability turned on 100 meters Typical (“autonomous”) GPS, w/Selective Accuracy… Original (civilian) GPS, w/Selective Availability turned on 100 meters Typical (“autonomous”) GPS, w/Selective Availability turned off 15 meters Typical DGPS w/Differential Correction < 5 meters Typical GPS w/WAAS & DGPS… < 1 meter Surveyors < 5 millimeters

Surveyors… • Use a form of differential correction in the field (using multiple receivers) Surveyors… • Use a form of differential correction in the field (using multiple receivers) • Can measure relative position between points very accurately (+/- a few millimeters) • Use local ‘control points’ (surveyed monuments, etc. ) to connect surveyed points to real world coordinates

http: //www. trimble. com/GNSSPlanning. Online/#/Settings http: //www. trimble. com/GNSSPlanning. Online/#/Settings

Probability of obtaining a GPS fix in the North Cascades GPS BIAS CORRECTION & Probability of obtaining a GPS fix in the North Cascades GPS BIAS CORRECTION & MOUNTAIN GOAT HABITAT ANALYSIS David Wallin & Adam G. Wells, 2006

Data Dictionaries (not w/Garmin units) Created with Pathfinder Office (in the lab) and transferred Data Dictionaries (not w/Garmin units) Created with Pathfinder Office (in the lab) and transferred to the Geo. Explorer-3 before using in the field. Allows creation of custom fields (attributes) and field values (defined lists of possible attribute values) for feature collection. So, for a database of TREES, a data dictionary might have: Species List (fir, pine, alder, etc) Type List (Either Deciduous or Conifer) DBH Number field (Enter size in inches) Date Auto-generated date field (day-month-year) Or, for a database of STREETS, you might create a data dictionary with: Name Text field (Enter Street Name) Type List (Ave, St. , Way, Place, Circle, etc) Type List (Arterial, Residential, Highway, Private Surface List (Paved, Gravel, Dirt) #Lanes Number field (Enter number of Lanes) Bike Yes/No (as to existence of Bike Lanes) But we’re not going to do that either…

Other Navigation Systems (Ground-based, USA) Loran-C (LOng Range Aid to Navigation) – Phased out Other Navigation Systems (Ground-based, USA) Loran-C (LOng Range Aid to Navigation) – Phased out in 2010… Coast Guard Radio navigation, 50 m, North America… Russia, Europe NDGPS (Nationwide Differential GPS – radio based corrections) Joint DOT (Highways and Railroads) and Coast Guard There is also Canadian DGPS and European DGPS Augmented systems (used in combination w/GPS ) Auto Navigation: GPS + GIS + Inertial Sensors (Dead Reckoning)

Other Navigation Systems (Regional Satellite Enhancements to GNSS) WAAS (Wide Area Augmentation System) (3 Other Navigation Systems (Regional Satellite Enhancements to GNSS) WAAS (Wide Area Augmentation System) (3 satellites*) USA (FAA) (2003) (USA, Canada, Mexico) MSAS (Multi-function Satellite Augmentation System) (2 satellites*) Japan (2007) EGNOS (European Geostationary Navigation Overlay System) (3 satellites*) Europe (2009) QZSS (Quasi-Zenith Satellite System) (1 {of 4} satellite*) Japan (2013? ) Under Implementation: GAGAN (GPS Aided Geo Augmented Navigation system) (2 satellites*) India SDCM (System for Differential Corrections and Monitoring) Russia (GLONASS) SNAS (Satellite Navigation Augmentation System) China * 1/2017 http: //gpsworld. com/the-almanac/

Other Navigation Systems (Regional Satellite Systems) IRNSS (Indian Regional Navigational Satellite System) India (serves Other Navigation Systems (Regional Satellite Systems) IRNSS (Indian Regional Navigational Satellite System) India (serves India only, not global coverage) 2013 – first satellite launched 2015? 2016? – 3 -7 satellites Bei. Dou(-1) (Quasi-Zenith Satellite System) China (serves China only, not global coverage) Now replaced by Bei. Dou-2 (Global system) * 1/1/2014 http: //gpsworld. com/the-almanac/

Other GNSS (Global Navigation Satellite Systems) GPS (Global Positioning System) USA Do. D (developed Other GNSS (Global Navigation Satellite Systems) GPS (Global Positioning System) USA Do. D (developed in 1960’s, ‘ 70’s and ‘ 80’s, functional in mid-80’s) 31 +/- satellites – global coverage (2 -5 m accuracy) GLONASS (GLObal NAvigation Satellite System) Russia (started in 1976, launched 1982 -1995, restored in 2000’s, global in 2011 ) 24 satellites* – global coverage (some smart phones/tables use GLONASS) Galileo European Union – Civilian based initiative (2010 first launches, testing) Different frequency than GPS (so could be jammed w/o losing GPS) 18 satellites* (Operational 12/15/16) 2020? * - 24+ satellites, global coverage (1 m accuracy) Bei. Dou Satellite Navigation System (BDS or Beidou-2 or Compass ) China 21 satellites* – functional as a regional navigation system (Asia) 2020? – 35 satellites, global coverage “Beidou-1” - 3 -4 satellites – regional only (China) - Test for Beidou 2 / Compass * 1/2017 http: //gpsworld. com/the-almanac/

The Future… Better Receivers/Transponders Better clocks in receivers means fewer satellites needed Components the The Future… Better Receivers/Transponders Better clocks in receivers means fewer satellites needed Components the size of a credit card (for < $100) Track L 1 and L 2 satellite signals for greater accuracy Additional (& Upgraded) Satellites (& WAAS) Multiple signals from each satellite w/different frequencies for fewer errors, etc. Upgraded ground support (augmentation) Dual/Tri/Quad systems (GPS & GLONASS & Galileo & Bei. Dou…) “ 100+ Satellites by 2020 with 30 -40 at a time”

The Future… Incorporation with other technologies (Cell phones, PDA’s, Cars) Hybrid/Augmented systems (also using The Future… Incorporation with other technologies (Cell phones, PDA’s, Cars) Hybrid/Augmented systems (also using cell towers, TV signals, RFID, Wi-Fi, etc. ) Indoor “GPS” or Enhanced GPS Ability to use low-quality satellite data (typically filtered out by masks) for estimating positions under canopy, inside buildings/cars, etc. Centimeter accuracy from smartphones… • Readily available tracking (finding) of your car, car keys, pet, child or package… (or your customers, ex-spouse, etc…) • Input shopping list: finds best price and availability, guides you to the store, to the floor, to the isle, to the shelf… • Car safety systems – each car knows what other cars are nearby (around the corner, etc. ), and car convoys, etc. (in-lane precise locations)

The Future… Does GNSS make us dumber…? Driver follows GPS directions onto train tracks… The Future… Does GNSS make us dumber…? Driver follows GPS directions onto train tracks… GPS directions send Mercedes driver downstream… Bus driver follows GPS directions, ignores signs, plows into overpass… http: //www. engadget. com/tag/gps+crash/ http: //news. bbc. co. uk/2/hi/uk_news/wales/north_east/7257555. stm Truck driver follows GPS past sign, becomes wedged in small farm lane…

The Future… Does GNSS make us dumber…? http: //www. engadget. com/ http: //news. bbc. The Future… Does GNSS make us dumber…? http: //www. engadget. com/ http: //news. bbc. co. uk/2/hi/uk_news/wales/north_east/7257555. stm

The Future… Does GNSS make us dumber…? Al Byrd’s three-bedroom home, built by his The Future… Does GNSS make us dumber…? Al Byrd’s three-bedroom home, built by his father on the western outskirts of Atlanta, was mistakenly torn down by a demolition company. “I said, ‘Don’t you have an address? ’ ” a distraught Byrd later recounted. “He said, ‘Yes, my GPS coordinates led me right to this address here. ’ ” http: //www. walrusmagazine. com/articles/2009. 11 -health-global-impositioning-systems/ http: //www. calfinder. com/blog/calfinder-news/oops-how-gps-led-contractors-to-demolish-the-wrong-house/

The Future… Global Impositioning Systems… Is GPS technology actually harming our sense of direction? The Future… Global Impositioning Systems… Is GPS technology actually harming our sense of direction? by Alex Hutchinson Walrus Magazine, Like any other human trait, navigational skill varies widely. . . as we enter the age of the global positioning system, which is well on its way to being a standard feature in every car and on every cellphone… neuroscientists are starting to uncover a two-way street: our brains determine how we navigate, but our navigational efforts also shape our brains. The experts are picking up some worrying signs about the changes that will occur as we grow accustomed to the brain-free navigation of the GPS era. Once we lose the habit of forming cognitive maps, we may find ourselves (unable to). She fears that overreliance on GPS… will result in our using the spatial capabilities of the hippocampus less, and that it will in turn get smaller. Other studies have tied atrophy of the hippocampus to increased risk of dementia… …a few years in a taxi can produce noticeable differences in our brains… researchers testing cognitive map formation in drivers found that those using GPS formed less detailed and accurate maps of their routes than those using paper maps. Similarly, a University of Tokyo study found that pedestrians using GPS-enabled cellphones had a harder time figuring out where they were and where they had come from. Their navigational aids, in other words, had allowed them to turn off their hippocampi. http: //www. walrusmagazine. com/articles/2009. 11 -health-global-impositioning-systems/

fini fini

Garmin GPSmap 60 -C(s) Garmin GPSmap 60 -C Waypoints & Tracks (Lines) No DGPS Garmin GPSmap 60 -C(s) Garmin GPSmap 60 -C Waypoints & Tracks (Lines) No DGPS No Data Dictionaries WAAS-Compatible Color screen Background Maps available Navigation (Go. To, Find, Speed, ETA, Distance, etc) 20 -30 Hours (AA batteries) 7. 5 oz. User friendly interface Additional Equipment: PDA/Laptop connections Remote antenna Bicycle handlebar mount

Garmin GPSmap 60 -C Power / Backlight Battery Life Zoom In/Out Find (Cities, Waypoints) Garmin GPSmap 60 -C Power / Backlight Battery Life Zoom In/Out Find (Cities, Waypoints) Mark (Waypoints) Quit (close screen) Rocker (navigation) Pan map or select options on a page Page Menu Enter

Garmin GPSmap 60 -C Main Screens Odometer ETA - EDA Velocity Off course GPS Garmin GPSmap 60 -C Main Screens Odometer ETA - EDA Velocity Off course GPS Accuracy Bearing / Course Heading Speed / Max Speed Time & Date

Garmin GPSmap 60 -C Satellite Page (or Skyplot) Accuracy Estimate Location Heading Indicator Skyplot Garmin GPSmap 60 -C Satellite Page (or Skyplot) Accuracy Estimate Location Heading Indicator Skyplot Horizon line Satellite Strength

Garmin GPSmap 60 -C Mark Waypoint Symbol Average Name Garmin GPSmap 60 -C Mark Waypoint Symbol Average Name

Garmin GPSmap 60 -C Main Screens Setup Map (Go. To) Profiles By default, the Garmin GPSmap 60 -C Main Screens Setup Map (Go. To) Profiles By default, the GPSmap 60 will record a Track (line feature) whenever the unit is turned on.

Garmin GPSmap 60 -C System Setup GPS On/Off/Demo WAAS On/Off Alkaline or Ni. MH Garmin GPSmap 60 -C System Setup GPS On/Off/Demo WAAS On/Off Alkaline or Ni. MH (rechargeable) battery Using WAAS decreases the battery life by ~1/3

Garmin GPSmap 60 -C Games… Virtual Maze Gecko Smak Garmin GPSmap 60 -C Games… Virtual Maze Gecko Smak

Garmin GPSmap 60 -C 1000 Waypoints WAAS Compatible 30 hours of battery life (2 Garmin GPSmap 60 -C 1000 Waypoints WAAS Compatible 30 hours of battery life (2 "AA" batteries) (Approximately 20 hours when using WAAS) Alkaline or Ni. MH (rechargable) batteries Waterproof 56 MB of internal memory for storing map detail (topo maps, etc) Trip computer (odometer, moving average, travel time, max speed. . . Quad Helix antenna (or connection to remote antenna)

fini fini

Accuracy vs. Precision… • GPS time ≠ UTC time (upon which Local time is Accuracy vs. Precision… • GPS time ≠ UTC time (upon which Local time is based) • GPS time (‘zero’) began at midnight, 6 -Jan-1980 • GPS is not perturbed by leap seconds (unlike UTC) • GPS clock is now ahead of UTC by 15 seconds • GPS 0˚ 0’ 0” ≠ Prime Meridian (thru Greenwich, England) • GPS system (WGS-84) ‘fits’ better at 90˚ west (U. S. A) • GPS 0˚ is east of the P. M. by ~ 105 m GPS is very precise. GPS is also very accurate to itself… but not necessarily accurate to other measurement systems (e. g. , UTC or the Prime Meridian…)

Trilateration Technically, GPS uses Trilateration (not triangulation) Triangulation involves the measurement of angles (which Trilateration Technically, GPS uses Trilateration (not triangulation) Triangulation involves the measurement of angles (which GPS doesn’t do) from a baseline. Trilateration uses measured distances. It requires two or more known reference (location) points and the measured distances between an unknown point and each of the reference points. In the case of GPS, each satellite serves as a reference point and the distance is measured from those points to the receiver.

GPS – Ellipsoid - Datum GPS uses the WGS 84 (World Geodetic System of GPS – Ellipsoid - Datum GPS uses the WGS 84 (World Geodetic System of 1984) as mathematical surface (model) of the earth WGS 84 is for all practical purposes the same as the Geodetic Reference System of 1980 (GRS 80) that was used for the North American Datum of 1983 (NAD 83) horizontal datum. Elevations are referenced to Height Above Ellipsoid (HAE)

Code vs. Carrier Phase Standard GPS uses ‘Code’ phase – comparing ‘pseudorandom’ code to Code vs. Carrier Phase Standard GPS uses ‘Code’ phase – comparing ‘pseudorandom’ code to determine distance (amount of time out of sync between satellite’s code and receiver’s code = distance satellite’s code had to travel) Carrier phase uses the Code phase to get close, then uses the actual carrier frequency wave pattern (that which carries the pseudo-random code) to increase the precision. For post-processing (Differential Correction), use Carrier phase recordings to get the best results (with a minimum recoding time of 10 minutes). Carrier phase also stores information from each satellite individually, allowing later comparison of the base station’s readings (error estimation) for each separate satellite recorded. Consequently, Carrier phase recordings use far more memory for storage than Code phase does.

GNSS Timeline 1960’s Early conceptual work, satellites 1970’s GPS satellites and technology development 1978 GNSS Timeline 1960’s Early conceptual work, satellites 1970’s GPS satellites and technology development 1978 – first portable GPS (25 lb backpack unit) 1980’s Functional navigations system (1983, free for public use, 8 satellites) 1989 – first handheld GPS 1990’s Civilian usages increases 1998 – first in-car GPS 2000 Selective Availability turned off 2003 WAAS 2005 – first GPS smartphone 2011 GLONASS 2016 Galileo ‘Operational’ 2020? Galileo & Bie. Dou fully functional?

Ionospheric Effects… • Space ‘weather’ can effect the speed of GPS signal, and thus Ionospheric Effects… • Space ‘weather’ can effect the speed of GPS signal, and thus the accuracy of the location estimate of the receivers Solar flares, coronal holes, etc. producing strong geomagnetic storms • Measured in Total Electron Content (TEC) of the Ionosphere See http: //sol. spacenvironment. net/~ionops/kml_files/ES 4 D_ionops_TEC. kml Real time TEC on Google Earth, Blue=good, Red = Bad • • • Degradation of GPS locations (more electrons = delay of signal) Especially in the mid-latitudes – can be highly variable In severe cases, can prevent Satellite fix entirely GPS receivers attempt to correct for effects Can also use GPS error to measure Ionosphere (TEC)…

National Map Accuracy Standards • • Horizontal accuracy for maps > 1/20, 000 is National Map Accuracy Standards • • Horizontal accuracy for maps > 1/20, 000 is < 1/30” (at > 90% of tested points) Horizontal accuracy for maps < 1/20, 000 is < 1/50” (at > 90% of tested points) Only for well defined points: monuments, benchmarks, intersections etc. Thus errors are only: – – • 1: 24, 000 ± 40 ft. (12. 9 m. ) accuracy 1: 62, 500 ± 104 ft. (31. 7 m. ) 1: 250, 000 ± 417 ft. (127. 1 m) 1: 30, 000 ± 50, 000 ft. (9. 5 mi. or 15. 2 km) Vertical accuracy for maps is < 1/2 contour interval at > 90% tested points – 20 ft. contour interval ± 10 ft. (3. 048 m. ) – 80 ft. contour interval ± 40 ft. (12. 2 m. ) Typical GPS accuracy compared to a 1: 24, 000 USGS Topo Quad Map: Horizontal = +/- 5 -20 m (potentially better than map standards) Vertical = +/- 10 -40 m (probably worse than map standards)