Finding Your Way— Maps, Compass and GPS Eagle Vision 2005

Map and Compass - as navigation tools Many people are of the mindset that with the introduction of GPS technology, the good ol’ Map & Compass are passé and no longer necessary… Believe that at your own risk! While GPS is a very powerful technology and while it can be used alone (without maps or compass), it has its limitations. Let’s have a look…

Limits of a GPS

Maps and Compass How to use a compass Basics of contour maps Orienting your map

The Basic Card Compass Parts of a Card Compass

Azimuth and Bearing—two ways of giving directions Azimuths uses 360 degrees degrees Bearings use 90 degrees and and cardinal directions– S 60 degrees E Back azimuth or bears can be used to determine where you are from known points

DIRECTIONAL ARROW ON BASE PLATE – Northwest COMPASS HOUSING (AZIMUTH RING) Chose your direction of travel—in this case 315 degrees Turn the Compass housing to 315 degrees How do you get from point A to point B?

NORTH END OF NEEDLE (RED) RED ARROW (on compass housing) (SHED) Put Red in the Shed. Follow the direction of travel arrow You are going 315 degrees

GN MNMN 13  11 Choosing direction can be tricky Declination---There is more than one north Magnetic North, Grid North, and True North Adjusting your compass to compensate

Contour Maps Information on the map Contours as isolines Reading contour maps

Information on the Map

Contours as isolines

Reading Contour Maps

Orienting your map for field use Latitude and longitude or UTM The magnetic field and compass Map orientation Known location Resection and triangle of error Approximations without a compass Getting from point a to point b—route selection

Measuring Distance Map measurements On-ground measurements Approximations--Pacing Measurements Slope problems Actual route traveled

GPS What is a Global Positioning System? The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of satellites placed into orbit by the U.S. Department of Defense. GPS works in any weather conditions, anywhere in the world, 24 hours a day. There are no subscription fees or setup charges to use GPS.

GPS

Elements of GPS Control Segment Master Control Station Computes precise satellite orbits Prepares updated information Sends messages to each satellite Monitor Stations Located throughout the world Track all GPS satellites Check operational health of the satellites Locate the exact position of each satellite Send information to the Master Station Ground Antennas Monitor and track the satellites from horizon to horizon Transmit correction information to individual satellites.

Elements of GPS Space Segment The satellites and the Delta rockets that launch the satellites from Cape Canaveral, in Florida A minimum of 24 functioning NAVSTAR satellites Circular orbits at an altitude of 10,900 nautical miles. Orbits tilted to Earth’s equator by 55 degrees to ensure polar coverage Powered by solar cells- satellites continuously orient themselves toward sun Each of the satellites, positioned in 6 orbital planes, circles the Earth twice a day

Elements of GPS User Segment The user segment includes the equipment of the military personnel and civilians who receive GPS signals Surveyors Aircrafts and ships Delivery vans and emergency vehicles Agricultural sector In-car navigation Recreationalists (hikers, hunters, and cyclists) EAGLE VISION PARTICPANTS

How It Works GPS units acquire their position on Earth by measuring their distance from three or more satellites For precise locations – including elevation measurements - the unit will need four satellites The GPS system measures the distance from the satellites to the receiver by timing how long it takes a radio signal to reach the receiver, then calculating the distance from the travel time Velocity X Time = Distance Radio signals travel at or near the speed of light

Pitfalls to Accuracy Obstruction Multi-path Issues Atmospheric Delay Human Error

Using Your GPS The Controls Getting from Point A to Point B Waypoints—before you leave Keeping track of where you have been Waypoints for data entry—data dictionary Putting your GPS data on a digital map Measuring distance and elevation