This website was created and is maintained by an educator that is dedicated to delivering..
As I complete pages, the site pages will be updated. Most pages will be broken until the page is complete.
Pennsylvania and its wilderness / water supply is in danger, because of the natural gas industry.
Note: Welcome to the new
This is a great place to start if you would like to learn about.
Navigation & GPS Technology!
GPS stands for Global Positioning System. The original name of this system was called NAVSTAR, which is the acronym for: NAVigation Satellite Timing & Ranging. GPS is a worldwide navigation system (developed by the U.S. D.o.D originally for military purposes) that consists roughly of 28 satellites (4 extra, in case one fails) that orbit the earth, along with their corresponding receivers on land. The satellites orbit the earths about 12,500 miles above the earth surface making two complete orbits every 24 hours in a certain spherical pattern at about 7,000 mph!
Each GPS satellite is powered by solar energy with battery backup for events like solar eclipses. The first satellite was launched in 1978 and the complete 24-satellite constellation was not finished until 1994. GPS was opened to the pubic for use in the 1980's, but Selective Availability or SA made it extremely inaccurate for civilian use. SA was intentional data error enforced by the U.S. Gov't for security purposes. SA was later removed in May of 2000.
The GPS satellites continuously transmit data through digital radio signals that contain information about satellite location & time. With this information the earth bound receiver (GPS Unit) can calculate various data such as: location, speed, altitude, etc.
Three satellites are needed to calculate a 2D fix/location (latitude & longitude) called trilateration (method for determining the intersecting point of three or more spherical surfaces), four satellites are needed to include altitude and is known as a 3D fix. Five or more satellites locked in by the receiver helps to increase accuracy. Many GPS units are capable of receiving data from 12 satellites at once. Remember without a GPS Unit the GPS navigation system is useless to you.
Parallel multi-channel design of GPS receivers have allowed them to be very accurate. Additional strengths added to GPS units are stronger processors, electronic downloadable maps & the new SiRF chip. These vital additions have allowed GPS receivers to complete the intrinsic calculations very quickly.
- Satellite Information is broadcasted in the sky in electronic code:
- Course Acquisition Code or CA code (used by public GPSr's, accuracy +/- 10m)
- Most high end consumer GPSr's can expect an accuracy of 6-20 ft. on average
- Precision Code or P code (used by military & Gov't personnel only, but the P code relies on the CA code to work, accuracy +/-3m)
- Governmental, Military & Professional GPSr's can be as accurate as centimeters!
- GPS Signals Three Bits of Information
- Pseudorandom code - Simply an I.D. code that identifies which satellite is transmitting information
- Ephemeris data - Tells the GPSr where each satellite should b (orbital information) at any time throughout the day
- Almanac data - Constantly transmitted by each satellite. It is important information such as the status of the satellites current date, time, health, etc..
- Ionospheric Inference
- Slows the GPS transmissions through the atmosphere
- Decreases accuracy by 5-10 meters
- WAAS improves this interference
- New GPSr compensations & calculations for the average delay through the atmospheric zones
- Satellite Geometry
- Refers to the satellite position in the sky
- Ideally one (1) satellite directly overhead, with three (3) other satellites spaced evenly across the sky
- This is the signal's path
- Reflected & Multi-path signals means the satellite to GPSr transmissions are bouncing off objects to create a reflected signal that reaches the receiver at an inaccurate time, so therefore increasing error. A good receiver and antennae can pick up such reflected signals. An example of a good receiver will have the SiRF chip installed. This chip can correct this reflected data with amazing speed and accuracy
- The receivers clock is not as accurate as the atomic clocks onboard the satellites, there is a slight error that occurs here
- This is inaccuracies of the satellites reported locations
- The more the better
- Mostly inoperable when indoors (SiRF improves this, along with high-sensitivity receivers), underwater & underground or within tunnels
- Is the relative position of the satellites at any given time
- Wide angles relative to each other are the best
- Poor geometry is displayed when the satellites are either in a line or in a tight group
- Selective Availability (SA), is intentional detration of the signal imposed by the United States Department of Defense (DoD)
- Setup to prevent US enemies from using the accurate GPS signals
- It was turned off in May of 2000
Improves GPSr accuracy to within 1 in. (2 mm). DGPS uses the difference between two measurements to improve GPS position and was put into operation by the U.S. Coast Guard. There are currently 60+ land based sites in the U.S. and it's provinces. DGPS is highly accurate for navigational purposes, but would be too costly, heavy and bulky for the consumer looking to use this technology out in the wilderness. Why? in order to use DGPS you must have an additional antenna and a DGPS unit, WAAS is more convenient to the outdoor enthusiast (WAAS is simply a form of DGPS)
DGPS does come in handy for other uses like: dam monitoring, the precise accurately of this system is an excellent way to control water levels and fill rates below the failure point of the dam for flood control.
|Two Methods Used By DGPS To Increase Position Calculations
An acronym for Wide Area Augmentation System. This is another U.S. developed navigational system (primary purpose was/is for civil aviation) that further enhances GPS accuracy by correcting minutely flawed data caused by atmospheric disturbance, timing and satellite orbit error.
WAAS is a form of DGPS that is very similar in the sense that it uses corrected data to further improve GPS accuracy, but does this in a different way. In WAAS, land-based stations (located at various points all across the U.S.) calculate any GPS satellite error at any time. The corrected data is up-linked from the land-based stations to the four visible WAAS satellites (#35, 38, 47 & 48) located along the equator at opposite ends of the United States. The WAAS satellites then beam the corrected data all across the continental U.S. & Alaska (soon Hawaii & Canada) where WAAS capable/enabled units can use the corrected data to further enhance the receivers true location. Garmin units display WAAS corrected data with a "D" within the satellite bar. In September of 2002, WAAS testing confirmed accuracy performances to 1-2 meters horizontally and 2-3 meters vertically throughout most of the continental U.S. and parts of Alaska.
For some users that have an obstructed view of the horizon due to mountains, trees, buildings, etc. it is not necessary to enable WAAS on your GPS unit, because the unit can not see the satellites so therefore, it can not communicate with the satellite to correct the data. But with today's technological changes, this may not be the case in the near future.
WAAS is a form of DGPS that is very similar in the sense that it uses corrected data to further improve GPS accuracy, but does this in a different way. In WAAS, land-based stations (located at various points all across the U.S.) calculate any GPS satellite error at any time. The corrected data is up-linked from the land-based stations to two WAAS satellites (#35 & #XX) located along the equator at opposite ends of the United States. The WAAS satellites then beam the corrected data all across the continental U.S. & Alaska (soon Hawaii & Canada) where WAAS capable/enabled units can use the corrected data to further enhance the receivers true location. In September of 2002, WAAS testing confirmed accuracy performances to 1-2 meters horizontally and 2-3 meters vertically throughout most of the continental U.S. and parts of Alaska.
European System: EGNOS (Euro Geostationary Navigation Overlay Service)
Russian System: GLONASS (Global'naya Navigatsionnaya Sputnkovaya Sistema)
Japanese System: MSAS (Multi-Functional Satellite Augmentation System)
From my knowledge, the only one compatible is EGNOS. I suggest further research to confirm my findings.
Can be defined as the horizontal & vertical lines on a map or globe that fix a position. Many grid systems have been created over the course of time by all different countries. The two most popular U.S. global grid systems are latitude & longitude (in three styles) and Universal Transverse Mercator (UTM).
A spherical coordinate system (global grid system) where the lines of latitude and longitude form an imaginary grid system over the globe. This system is used for navigational purposes on land, sea & air. You probably learned about this grid system in school.
- These imaginary lines or degree (o) run horizontally around the Earth and tell you how far north or south something is from the Equator
- All lines of latitude run parallel to the equator and/or horizontal in direction on the globe or map when north is pointing up
- The equator splits the globe into two equal hemispheres (northern & southern) and is the staring point for the latitudinal numbering system
- Anything above the equator is in the northern hemisphere and is followed by an N
- Ex. All of the United States is in the Northern Hemisphere
- Ex. 41oN latitude (indicates the line of latitude above or north of the equator)
- PA is roughly located within 39oN - 42oN latitude
- There are 90 distinct lines of northern latitude
- Anything below the equator is in the southern hemisphere and is followed by an S
- Ex. Australia is located below the equator so therefore it is in the Southern Hemisphere
- Ex. 23oS latitude (indicates the line of latitude below or south of the equator)
- There are 90 distinct lines of southern latitude
- There are 180 distinct lines of latitude
- Five (5) lines are prominent, they are listed below
- The Equator is located at 0o latitude
- Divides the earth in half
- The Tropic of Cancer is located at 23oN latitude
- Line of latitude in which the suns rays are at the northern most point of direct sunlight on the earth
- The Arctic Circle is located at 66.ooN latitude
- The point in which the suns rays do not reach the region (66.5oN - 90oN) at certain times of the year and vice versa, total daylight or darkness
- The North Pole is located at 90oN latitude
- The northern most point on the globe
- The Tropic of Capricorn is located at 23oS latitude
- Line of latitude in which the suns rays are at the southern most point of direct sunlight on the earth
- The Antarctic Circle is located at 66.5oS latitude
- The point in which the suns rays do not reach the region (66.5oS - 90oS) at certain times of the year and vice versa, total daylight or darkness
- The South Pole is located at 90oS latitude
- The southern most point on the globe
- Anything up (nor ht) of the Equator increases in number and is followed by an N for North.
Anything south (south) of the Equator increases in number and is followed by a S for South.
- All lines of latitude are followed by a N or S
- All lines of latitude are parallel to one another and are known as parallels
- These imaginary lines or degrees (o) run vertically around the earth and tell you how far east or west something is from the Prime Meridian, which is located in Greenwich, England, north to the pole and south to the other pole
- Lines of longitude run from the North Pole to the South Pole, so therefore..
- all lines of longitude converge at the pole and are not parallel!
- The Prime Meridian crosses Greenwich, England and is the starting point for the longitudinal numbering system
- The Prime Meridian is located at 0o of longitude
- The International Dateline is directly opposite of the Prime Meridian
- The International Dateline is located at 180o of longitude
- So therefore, the Prime Meridian & the International Dateline split the earth into two equal hemispheres, they are eastern and western
- Anything to the right of the Prime Meridian is in the eastern hemisphere back to the International Dateline
- From this line of longitude heading east there are 180 lines or degrees(o) E
- Any longitudinal line heading west of the Prime Meridian is in the western hemisphere back around to the International Dateline
- From this line of longitude heading west there are 180 lines or degrees (o) W
- Ex. 076oW longitude, indicates line of longitude west of the Prime Meridian
- Ex. The U.S. is located in the western hemisphere and all of the lines of longitude are followed by a W
- PA is roughly located within 74oW - 80oW longitude
- Anything to the right of the Prime Meridian is in the eastern hemisphere back to the International Dateline
- Anything to the right (east) of the Prime Meridian increases in number and is followed by an E for east
- Anything to the left (west) of the Prime Meridian increases in number and is followed by a W for west
- All lines of longitude are followed by either E or W
- All lines of longitude are known as meridians
- 1o (degree) is 69.05 miles or 111.12km
- 1' (minute) is 1.15 miles or 1.85 km, which is also 1 nautical mile
- 1" (second) is .019 miles or about 101 feet or 33.7 yards or .03 km
- 1,000th of a minute is.. 6 feet or 2 yards
- 100,000th of a decimal degrees is.. 3.65 feet or 1.22 yards, which is slightly over 1 meter
- These measurements are consistent when using latitude
- These measurements are inconsistent when using longitude
- At the equator they are consistent, but slowly decreases in distance as you approach the poles
- Where two lines of latitude & longitude cross a reference point or coordinate follows. Coordinates generally list the line of latitude first
- Generally written hemisphere latitude & hemisphere longitude
- Coordinates may be expressed in three (3) different formats
- Degrees, Minutes & Seconds - 41o19'30" N 76o17'07" W
- 60" seconds to 1' minute
- 60' minutes to 1o degree
- 180o to one eastern or western hemisphere
- 90o to one northern or southern hemisphere
- Degrees & Decimal Minutes - 41o19.505' N 76o17.113' W
bullet 60' minutes to 1o degree
- 60' minutes to 1o degree
- 1,000 (1,000th) to 1' minute
- Decimal Degrees - 41.32508oN 76.285333oW
- 100,000 decimal degrees to 1o degree
- Degrees, Minutes & Seconds - 41o19'30" N 76o17'07" W
*The coordinates above are for the Ganaga Falls (100'+) located in Ricketts Glenn State Park off Rt.118
Ex1. 41o26'38" N 76o40'43" W in Degrees, Minutes & Seconds
Ex2. 41o26.626' N 76o40.713' W in Degrees & Decimal Minutes
Ex3. 41.44377o N 76.67855o W in Decimal Degrees
Ex1. 41o25'49.1" N 76o40'14.0" W in Degrees, Minutes & Seconds
Ex2. 41o25.826' N 76o40.234' W in Degrees & Decimal Minutes
Ex3. 41.43043o N 76.67056o W in Decimal Degrees
*The above coordinates are for “Dry Run Waterfalls Parking Area" located off Dry Run Road, which is accessible off Rt.87. The Dry Run Waterfalls are a very pretty waterfall that is about 20' high.
- Both examples listed above give three coordinates formats for the same location. They are just listed in the 3 formats that the Latitude & Longitude Grid System can use Most GPSr allow you to select a multitude of formats.
A global grid system that splits the earth into 60 zones that run east to west, each zone of which is 6o wide for two reasons; reduced distortion when converted from a spherical globe to a flat paper map & the ease of use on a paper map with northing & easting values being measured in meters. This system starts at the zone meridian (180o aka the International Dateline, when referencing to the latitude & longitude system) and uses letters of the alphabet along with easting & northing values.
UTM maps do not cover areas above 84oN. latitude & 80oS. latitude. The remaining degrees above & below these lines are drawn using Universal Polar Stereographic Grid (UPS). This grid system will be talked about at a later time.
Definition #2: UTM stands for Universal Transverse Mercator. This system is popular for use on land. Unlike lat. & long., which projects imaginary grid lines on the globe. UTM projects section of the globe on a flat surface, like a map. Again there are 60 sections or zones in the UTM system that cover 6o each. This type of grid system starts with section 1 at 180o - 174o, continuing west to zone 60. Two other elements describe this system in greater detail; they are easting and northing values. Easting & northing values measure how far in meters, within the zone the reference point is.
- Measure east to west or west to east
- Easting measurements increase in value as you move left to right & decrease in value as you move right to left
- The point of origin for the easting lines is the International Dateline (which you already knew from above information)
- Measure north to south or south to north
- Northing measurements are always measured in relevance to the equator
- Northing values above the equator range from 0000000mN (equator) to 9334080mN (84oN Latitude)
- Northing measurements increase in value as you move north from the equator
- Northing values below the equator range from 10000000mN (equator) to 1110400mN (80oS Latitude)
- Northing measurements south of the equator decrease in value as you move away from the equator
- So therefore, northing values (no matter what your location is above or below the equator) always increase in value as you move north & decrease in value as you move south!
Ex. 18T 295718mE 4621044mN
* The above example is coordinates in UTM format for "Owassee Rapids" on the Pine Creek. This rapids is a Class II rapid on a 6 scale system
- 18T represents the zone
- 295718mE (represents the Easting Value)
- 4621044mN (represents the Northing Value)
* Notice how NG TOPO combines the zone letter & splits the easting & northing values. Also note how the numbers are all the same size
Ex. 18 T 363327 4591410
* The above example is coordinates in UTM format for “Split Rock" on the Loyalsock Trail. This landmark is a cool rock that split over time creating crevasses between the rock
- Notice how the GPS splits the zone, the zone letter, easting value & northing value. But does not tell you which is which. So you must have some knowledge of UTM to interpret this coordinate
- The neat thing about UTM is, you can compare the distance between two reference point by taking the difference of the two coordinates (as long as they are within the same zone)
- Pennsylvania is located in UTM Zone 17T & 18T
It's quite simple actually. If you remember each UTM grid line is divided by 1000 meters, with this in mind, it's real simple to figure out a waypoint coordinates.
Ex. Someone has told you that there is a really cool vista near Blackwell off the MST known as the “Materhorn." They show you its general location on the map, but neither of you know the coordinates and you would like to plot it on your map & in your GPS.
To figure this out, take your UTM legend that shows the map scale and measure from one of the main UTM easting lines, either 302000m.E. or 303000m.E.. If you use 302000m.E., then you add those meters to the last three 0's. If you use 303000m.E., then you subtract those meters to the last three 0's and vice versa for the northing lines.
Easting line: 302000m.E. + 129 (measured meters) = 302129m.E. (Easting value)
Northing line: 4602000m.E. + 763 (measured meters) = 4602763m.E. (Northing value)
Coordinates: 302129m.E. 4602763m.E.
|The Universe Transverse Mercator Grid for the United States||Determining a UTM Grid Value for a Map Point|
The MGRS is the global grid system designed by the U.S. Military, used by the U.S. Military and NATO Forces. This system is very similar to the UTM grid system, except that the majority of the numbers (first two) are replaced with letters & the letters run horizontally instead of vertically.
Example Coordinates in different formats
- UTM: 12 S 0501788m.E. 3690619m.N.
- MGRS: 12 S WB 01788, 90619
- GPSr: 12 SWB 0178890619
The MGRS system divides the globe into 8o sections instead of 6o sections like the UTM grid system. So therefore, there are 19 sections, each covering 8o that run horizontally, except for the northern most section which covers 10o. The letters start from the southern most hemisphere using the letters C, D, E, F, G, H, J, K, L, M, (all in southern hemisphere) N, P, Q, R, S, T, U, V, W, X (all in the northern hemisphere). The southern most section of the MGRS system is assigned letter C & the northern most grid section is letter X. This grid system is not popular among outdoor enthusiast, because USGS maps do not display this grid on their maps.
- Since this grid system is not widely used by the average consumer I will only briefly explain how to figure out northing & easting numbers. Basically, you follow the coordinates on the X & Y axis and use a chart to convert the numbers to letters (the first two). In figuring out easting you use a chart to convert the first two numbers to a letter by which zone its in and which numbers they are (01-08).
- The first two digits in the northing number are converted to a letter by using another table in conjunction with the zone and where they intersect. Converting the northing number is a little more confusing than the easting number, but like anything with practice, it becomes easier.
A special uniform grid system developed for use in the Arctic & Antarctic regions of the world. The UTM grid system can be used for these regions also, but the zones are very narrow and confusing to read if using UTM so therefore the UPS was created. UPS does share some similarities with the UTM system in that they both have eastings and northings and each is 1000 meters (.62 miles) in size.
This is the national grid system for Great Britain and Great Britain only. This grid system is separated into square sections each 100km in size (62.1 miles). Each grid is assigned a double letter that is 7 grids wide by 13 grids high. This grid system is also similar to the UTM system in that: it has easting and northings, its unit of measure is in metric, the last three numbers a grid coordinate represent meters and its easy figure out distance between two coordinates within the same grid.
I will not go into great detail for the MGRS, UPS, OGSB, MGS grid systems. The two primary navigational systems used by the United States is the UTM and Latitude & Longitude. There are a lot of great resources out on the Internet if you would like to learn more about these grid systems.
This grid system was developed and operated by amateur radio operators. It divides the world into rectangular grids each 20o of longitude and 10o of latitude for a total of 18 grids wide (A-R) running east to west and 15 grids high (D-R) running south to north. Each grid is identified by two letters and are further subdivided by 2o by 1o and labeled with two numbers (00-99). This grid system subdivides one more time; each sub-area is 5' of longitude by 2.5' of latitude and is labeled with the letters AA-XX.
FYI: Grid letters above and to the right of the letter “J" are located in the northern hemisphere and in the eastern hemisphere.
To figure out how your map has been setup look over the legend and look to the edges of the map. The USGS Topo! software tells you the datum used in the upper right & lower right-hand corners. It can also generate maps in four formats (3 lat. & long. & UTM). The format markings are along the outer edges of the map & would contain the coordinates.
The USGS maps you purchase at outfitters are 7.5' topographic maps. You will find (9) 2.5' blocks on each map. 7.5' is the distance it covers in both directions using the latitude & longitude grid system. It will also contain the UTM grid system with markings every 1000 meters.
* The map below would contain UTM marks from: 4584 – 4597 for northing (south to north) & 291 – 301 for eastings.
Note: When using the National Geographic TOPO! software set the grid markings to:
- 450 seconds to see each USGS Quad Map on the screen when using latitude & longitude
- 150 seconds to see each 2.5' quadrant when using latitude & longitude
- Degrees, Minutes & Seconds: The map is divided by tick marks every 30" for both latitude & longitude
- Degrees & Decimal Minutes: The map is divided by tick marks every 500' for both latitude & longitude
- Decimal Degrees: The map is divided by tick marks every .00833o for both latitude & longitude
Latitude & Longitude
- Eastings: The map is divided by tick marks every 805 meters (.5miles)
- Northings: The map is divided by tick marks every 805 meters (.5 miles)
- Navigation begins with a point and everything around that point. So the circle is a very important part of navigation. The circle in navigation is subdivided into degrees, minutes, seconds and mils.
- All of our navigation systems, formats and datum's are based on this circle design.
- The most common subdivision is the degree (o).
- There are 360o in a circle;
- 0 is the start,
- a 1/4th of a circle is 90o,
- 180o to a 1/2 circle,
- 270o to 3/4th of a circle and
- 360o to a complete circle, 0o & 360o are the same.
- When working with degrees, in the case of adding & subtracting the values, it starts at 0o - 359o.
- The degree's subdivision is the minute, expressed by a tick mark (').
- There are 60' to one degree (o).
- The minute's subdivision is the second, expressed by two tick marks (").
- There are 60" to one minute (')
- When working with minutes & seconds, in the case of adding & subtracting the values, it starts at 0 – 59.
- Various Examples Listed Below:
- 37" + 21" = 59" (almost 1 minute)
- 45" – 15" = 30" (half a minute)
- 46" + 33" = 73" = 1' 13" (1 minute & 13 seconds)
- 1' 07" + 49" = 1" 56" (1 minute & 56 seconds)
- 5' 45" – 2' 15" = 3' 30" (3 minutes & 30 seconds)
- 270o 15' 45" + 10o 7' 23" = 280o 23' 08" (280 degrees, 23 minutes and 8 seconds)
- 165o 23' 17" – 42o 12' 48" = 123o 11' 31" (123 degrees, 11 minutes and 31 seconds)
- 76.257o = 76o (.257 x 60') = 15.42' (remember 60 degrees to 1 degree)
- Answer: 76o 15.42'
- 320.926o = 320o (.926 x 60') = 55.56'
- Answer: 320o 55.56'
- If you want to convert these values the opposite way, just divide 60, instead of multiplying
- Using the same examples above we can further break down the decimal minutes to seconds.
- 76.257o = 76o
- (.257 x 60') = 15.42' (remember 60 seconds to 1 minute) = 76o 15.42'
- (.42 x 60) = 25.2" exactly or rounded to 25"
- Answer: 76o 15' 25"
- 320.926o = 320o
- (.926 x 60') = 55.56'
= 320o 55.56'
- (.56 x 60) = 33.6" exactly or rounded to 34"
- Answer: 320o 55' 34"
- (.56 x 60) = 33.6" exactly or rounded to 34"
- (.926 x 60') = 55.56' = 320o 55.56'
- If you want to convert these values the opposite way, just divide 60, instead of multiplying
- Simply add or subtract 180o to your bearing
- 74o 32' 45" = 74o (+ 180o) = 254o
- Answer: 254o 32' 45"
- 315o 45' 30" = 315o (- 180o) = 135o
- Answer: 135o 45' 30"
- 74o 32' 45" = 74o (+ 180o) = 254o
- A circle can also be subdivided into mils, instead of degrees, minutes & seconds
- The cool thing about mils is there is no subdivision of a mil, so there are no silly conversions!
- A full circle is made up of 6,400 mils and/or 1 mils is one sixty-four hundredths (1/6400) of a circle
- Mils are best related when you know how to convert the two from one to another.
- Examples below:
- 1 mil = 360o / 6400 = .05625o
- 1o = 6,400 mils / 360 = 17.778 mils
- Examples below:
- Simply Multiply the Number of Degrees by 17.778
- Examples Below:
- 68o = 68o x 17.778 =
- Answer: 1,208.904 exactly or 1,209 mils
- 68o = 68o x 17.778 =
- To convert degrees, minutes & seconds, be sure to convert it to decimal degrees, then multiply by 17.778
- Simply Multiply the Number of Mils by .05625
- Example Below:
- 4,200 mils = 4,200 x .05625 =
- Answer: 236.25o
- 4,200 mils = 4,200 x .05625 =
- North (N) = 0o = 0 mils
- Northeast (NE) = 45o = 800 mils
- East (E) = 90o = 1,600 mils
- Southeast (SE) = 135o = 2,400 mils
- South (S) = 180o = 3,200 mils
- Southwest (SW) = 225o = 4,000 mils
- West (W) = 270o = 4,800 mils
- Northwest (NW) = 315o = 5,400 mils
* measurements were calculated and rounded to the nearest 100th, so they are not exact, but very close.
.06 miles = 317ft. or 105yds.
.5 miles = 2,640ft. or 880yds.
.6 miles = 3,168ft. or 1,056yds.
.7 miles = 3,696ft. or 1,232yds.
.75 miles = 3,960ft. or 1,320yds.
.8 miles = 4,224ft. or 1,408yds.
.9 miles = 4,752ft. or 1,584yds.
1 mile = 5,280ft. or 1,760yds.
1 mile = 63,360 inches
|1 mile = 160,900 centimeters
1 mile = 1,609 meters
1 mile = 1.61 kilometers
1 kilometer = .62 miles
www.onlineconversions.com is a great website that converts just about anything!
Can You Read, Make Out and Interpret distance on a Paper Map?
Yes, you can (to a certain extent) do this by knowing the distance between o (degrees), ' (minutes), " (seconds) or UTM's meters, but the best way is:
- Use the legend to interpret distance along with some sort of straight edge instrument.
- Use a special ruler that is calibrated to read minutes & seconds on a 2.5' x 2.5' grid.
- Use the ruler on your compass (make sure the scale on the map & the compass match)!
- Draw a finer grid on your map (subdivide the map into smaller grids).
- Make sure the grid lines are easy to interpret distance measurements and are easy to read.
- When interpreting distance on a paper map, it takes some knowledge & practice to accurately interpret distance.
- Latitude distance is consistent.
- Longitude distance is not! If you remember from my bulleted information about longitude, as you move north or south away from the equator, the distance between grid lines decreases. The only time both latitude & longitude are the same is at the equator.
Declination is the difference between magnetic north (the direction your compass points) and true or grid/map north (the direction the map indicates is north, which is the North Pole). Declination difference will be in degrees and varies depending on what part of the US you live in. The varying degree can be as much as +18o. Here in central Pennsylvania it's oughly 11oW or -11o.
You must know the declination of the area you are in, for example:
- Declination around this area Central PA is roughly 11oW or -11o
- Declination in PA is roughly 8.5o - 12.75oW or -8.5o - -12.75o.
- Since we are to the right of the Magnetic North line we add the declination difference to our compass to get to a certain point on a paper map.
- (Remember East is Least, West is Best!)
* Determining Your Declination – Expressed as either East or West Declination according to your present location of the magnetic North Pole
If your present location is right of the magnetic pole line, it is considered
If your present location is left of the magnetic pole line; it is considered
Click either map to view full size image
Maps courtesy of: National Geophysical Data Center
Continental US in a pdf document for download
North America in a pdf document for download
East is Least, West is Best – Which means you subtract east declinations and add west declinations to your calculations depending on which side of the magnetic pole line you stand on. The examples below show you how do do this.
Location: Central Montana
* Most all maps will tell you the declination difference somewhere on the legend, the USGS Topo! software maps declination is located in the lower right corner.
* Declination changes due to the floating magnetic poles. The maps above are current as of 2011.
- Extra batteries for you GPS receiver
- Paper maps of the area
- State Forest Map or Park Map of the area
- Altimeter (helps to better estimate your location on the mt. when you do not have a gps)
- Pedometer (not necessary, but may help you to track your steps)
- Survival Blanket (space blanket)
- Water tablets
- Strike anywhere matches or Butane Lighter
- Cotton balls dipped in vaseline
- First Aid Kit
- Band aids
- Gauze Pads
- Tick Twister
- Medical tape
- Duct tape
- Antibiotic cream
- Travel notebook
- Log your adventure
- Notable crossings, ridge lines, valleys, views, terrain, scenery, camps, runs, etc…
- Draw pictures or diagrams if it helps
- Be descriptive
- Record the time you were there
- Know the sunset & sunrise times
- Be aware of the weather and possible elements around that time of year
- Make sure someone knows that you out in the wilderness & your general location
2D Operating Mode – In GPS terms, it is a two-dimensional fix on a location that only contains a horizontal fix without elevation. A minimum of 3 satellites is required for this operation mode.
3D Operating Mode – In GPS terms, it is a three-dimensional fix on a location that includes both a horizontal fix and elevation. A minimum of 4 satellites is required for this operating mode.
Almanac Data – Information transmitted by the GPS Satellite telling the receiver its current health & orbital status.
Altimeter – An instrument used to determine elevation.
Altitude - The elevation above sea level or above the earth surface.
Atomic Clock – A very precise clock. Each GPS satellite contains many of these clocks. They are extremely accurate, because of the rubidium & cesium components (one-second error per one million years).
Azimuth – Aka bearing, is the compass position between your present position and your destination. It is mostly expressed in degrees (o), but sometimes can be displayed in mils.
- North = 0o or 360o
- Northeast = 45o
- East = 90o
- Southeast = 135o
- South = 180o
- Southwest = 225o
- West = 270o
- Northwest = 315o.
Barometer – An instrument used to determine the pressure in the air.
Compass – A navigational instrument used to find direction.
Coordinates - These are numbers and letters that precisely label any and all positions on earth. Every position on earth has a unique coordinate. The displayed coordinate of a position is determines by the grid & datum used.
Coordinate Point – A point associated to a coordinate system in which a coordinate is identified at where the meridian and the parallel intersect.
Coordinated Universal Time (UTC) – This system of time replaced the Greenwich Mean Time (GMT) in 1986 and is now the world standard. This time compensates for the leap year and any changes in the earths rotation.
Course Acquisition Codes (CA code) – The standard code transmitted by GPS Satellites. This transmission code allow users to utilize the global positioning system. The information contained within this code is for civilian use and is accurate to within 10 feet. The best reception I ever had in combination with WAAS was 6 feet!
Data Formats – The way in which the map has been written to calculate distance and the grid system used. There are generally three data formats; each format is best suited to a particular grid system.
- Metric: The European & world unit of measurement, Ex. Kilometer, meters
Grid System Preference: UTM, UPS, MGRS & OSGB
- Nautical: Used on the open waters by sailors & others, this is used in reference to marine charts, Ex. Nautical mile, knots
Grid System Preference: Marine Charts, Latitude & Longitude
- Statue: The U.S. units of measure, such as: feet, Fahrenheit, miles per hour.
Grid System Preference: Latitude & Longitude
Declination – Is the difference between the North Pole and the Magnetic Pole in degrees or mils in reference to your position. Most maps display this in degrees
The United States Department of Defense (DoD) – Maintains and controls the GPS system along with a variety of other duties.
Differential GPS (DGPS) – An extension of the GPS system used by WAAS. This system consists of land-based radio beacons located a various locations across the country (east coast, middle & west coast) that transmits corrected GPS position data. First implemented by the U.S. Coast Guard. DGPS improves GPSr accuracy to within 10 meters, I have experienced an improvement to within 10 feet! DGPS does have the potential to increase positional accuracy to within 1 in. (2 mm)! But not without added equipment & substantial costs; not to mention we civilians do not have access to the P-Code.
Easting – Similar to a northing, except is refers to the distance east or west of a fixed reference point, which is the International Dateline. Again you will see this value used in the UTM, MGRS and others.
Elevation – The distance above or below the mean sea level.
Elevation Profile - Is a cross-section of the trail, route or drawn route that displays the changes in elevation at every point on the trip. This is an invaluable feature provided by topographical software that displays to you how easy or strenuous the hike may be.
Elevation Profile – shows the elevation gain or loss along a trail from a horizontal aspect. This information is very informative when it comes to the amount of time and miles you will hike when planning out a hike or backpacking trip.
Emphemeris Data – Data that is valid for several hours and contains current satellite position and timing information. This emphermeris data is transmitted by the GPS satellite as part of the satellite data message.
Geographic Coordinates – A coordinate values given as latitude and longitude.
GPS – A satellite system used to navigate. This system enables anyone on Earth who owns a GPS receiver to know where they are at any time, no matter what the weather.
GPSr – This is short for the GPS receiver. The GPSr communicates with the satellites to calculate the fixed or moving location of the individual or object that is equipped with the unit.
Grid – The horizontal & vertical lines on a map or globe that fix your position. Many grid systems have been created over the course of time by all different countries. The two most popular U.S. global grid systems are latitude & longitude (in three styles) and Universal Transverse Mercator (UTM).
Grid North – aka True North, both are used interchangeably. This is the direction to the North Pole.
Ionosphere – A region of the earth's atmosphere 50–250 miles wide (50–400 km) and affects GPS radio waves due to the incoming solar radiation.
L-Band – The radio frequency that carries the L1 & L2 frequency that consists of the all GPS satellite data and operates within the range of 390-1550 Mhz.
Latitude & Longitude – A spherical coordinate system (global grid system) where the lines of latitude and longitude form an imaginary grid system over the globe. This system is used for navigational purposes on land, sea & air. You probably learned about this grid system in school. The UTM systems is based off this system, but instead uses zones (60 of them.)
Latitude – These imaginary lines or degrees (o) run horizontally around the Earth and tell you how far north or south something is from the Equator. The equator line of latitude is 0o. From the Equator there are 90 lines of latitude that extend northward to the North Pole and are followed by the letter N to indicate north. There are also 90 lines of latitude that extend southward to the South Pole and are followed by the letter S to indicate south. Ex. 41oN latitude (indicates line of latitude north of the equator). PA is roughly located within 39oN - 42oN latitude. All lines of latitude are parallel to one another and are known as parallels.
Local Area Augmentation System (LAAS) – A real-time DGPS correction system with a 20-30 mile radius developed by the U.S. Federal Aviation Administration for landing aircraft at small to medium-sized airports. The LAAS system is extremely accurate to within 1 meter on the horizontal and vertical plane.
Longitude – These imaginary lines or degrees (o) run vertically around the Earth and tell you how far east or west something is from the Prime Meridian (Greenwich, England). 0o longitude is located in England. From this line of longitude there are 180 lines or degrees (o) that run east of the Prime Meridian and 180 lines that run west of the Prime Meridian. The International Dateline is the line where the two 180o of longitude meet. The U.S. is located in the western hemisphere and all lines of longitude are followed by a W. Ex. 076oW PA is roughly located within 74oW - 80oW longitude.All lines of longitude are parallel and are known as meridians. Two lines that intersect are perpendicular to one another. Where these two lines cross a reference point or coordinate follows. Coordinates generally list the line of latitude first. Ex. N41 26.987 W76 38.606. This is the coordinate of “Split Rock" located at mile 34.28 on the Loyalsock Trail. N41 represents the line of latitude and the 5digit extension that follows this example stands for, degrees & decimal minutes according to the WGS84 datum. The 4-5digit number added to each degree is the specific or exact location within each degree. These digits are needed because miles of land separate each degree of latitude & longitude. There are basically three global grid systems based off lat. & long. They are: decimal degrees, degrees & decimal minutes or degrees, minutes & seconds.
Magnetic North – The direction in which a compass needle always points. This magnetic pole is located in northern Canada and has a 12o declination to the North Pole in our area of the globe. Most maps are laid out in true (grid) north. (You must know the declination from your location to correctly navigate to your destination with a compass.) Points to the magnetic North Pole, which is located in northern Canada. All compasses made for use in the U.S. point to the magnetic North Pole, not true north. Most papers are laid out in true (grid) north. You must know the declination from your location to correctly navigate to your destination.
Map Datum - All Maps are drawn with respect to a reference point (specific location). This reference point is known as a datum, so therefore datum's are used as a basic of calculating and measuring. Since maps generally only cover a portion of the earth in a larger scale, datum's have been created to pinpoint a certain location. The transition from a global view to a paper map view is where a datum comes in. Similar to the grid system, just on a more precise scale, 100's of map datum's been created by the U.S., and other countries for navigational purposes. The U.S. generally uses the World Geodetic System 1984 (WGS84) or North American Datum 1927 (NAD27).
Map Scale – Maps are scaled out according to a certain measurement. Most maps, especially USGS maps are scaled to 1:500,000, 1:100,000 & 1:24,000. The most popular and most detailed map scale is 1:24,000, which means that for every one inch on the map, it represents 24,000 inches on the ground. Generally the 1:24,000 covers less area on a map than the 1:100,000 and so on.
Meridian – Lines of longitude, a term used in grid systems. Meridians are imaginary lines that run from the North Pole to the South Pole. Each meridian is perpendicular to all circles of latitude at the intersection points.
Metric – The European & world unit of measurement with a base number of ten (10) and a base unit of a meter. Ex. Kilometer (km), meters (m), centimeter (cm), millimeter (mm). Grid System Preference: UTM, UPS, MGRS & OSGB.
Nautical – Used on the open waters by sailors & others. Nautical is referenced to marine charts. Ex. Nautical mile, knots. Grid System Preference: Marine Charts, Latitude & Longitude.
Navigational Message – Information within the GPS satellite signal that contains velocity, time, position.
Navigational Screens – Visual screens or pages that display statistical data about your adventure. Some data on these pages can be changed and some can not.
* Garmin Receivers tend to display 5 or 6 main pages or more (which is up to the user). The 6 basic pages are:
- Map Page: displays the map of the area you are in, along with variable data fields.
- Compass Page: displays the compass bearing, along with variable data fields.
- Trip Computer Page: displays a variety of variable statistical & navigational data used on the expedition.
- Satellite Page: displays the satellite locations in the sky, how many your GPSr has locked and the accuracy of the receiver.
- Menu Page: displays icons where the user can change preferences and advanced features of the unit.
- Altimeter Page: displays altimeter readings or profile & barometric pressure plots, plus more.
Navigational Statistics – Calculated data according to its title. Many GPS receivers are capable of recording or displaying a wide variety of statistical data that you may find useful on your adventure.
* Examples of such data that are seen on the Garmin GPSMAP 60CSx are:
Accuracy of GPS, Bearing, Course, Depth, Distance To Destination, Distance To Next, ETA At Destination, ETA To Next, Elevation, Glide Ratio, Glide Ratio To Destination, Heading, Odometer, Off Course, Pointer, Speed, Speed – Maximum, Speed – Moving Average, Speed – Overall Average, Sunrise, Sunset, Time To Destination, Time To Next, Time of Day, To Course, Trip Odometer, Trip Time – Moving, Trip Time – Stopped, Trip Time – Total, Turn, Velocity Made Good, Vertical Speed, Vertical Speed to Destination, Water Speed, Water Temperature, Waypoint At Destination, Waypoint At Next.
NAVSTAR – The original name of the GPS Satellite System. It stands for NAVigation Satellite Timing & Ranging.
Northing – This refers to the distance north or south of a fixed reference point such as the equator. You will see this value used in the UTM system and some others like the Military Grid Reference System (MGRS).
Parallel – Lines of latitude, a term used in grid systems. A circle or approximation of a circle on the surface of the Earth. Parallel's are parallel to the Equator (0o latitude) and connecting points of equal latitude.
Precision Code (P code) – This is another GPS transmission code that relies on the CA code to function properly. The U.S. military and the U.S. Government use the P code. This code increases GPS accuracy to within a foot. The P code is not accessible to the public. This code is encrypted and reset weekly to prevent unauthorized use. Also known as the Y-Code.
Prime Meridian – The internationally accepted "prime meridian" located through Greenwich, England and has a longitudinal (vertical) measurement of 0 degrees.
Pseudo-Random Code – Helps to separate the GPS Signal sent by the satellite and mirrored by the receiver from background noise.
Quadrifilar Helix Antenna – A type of GPS antenna (used in the GPSMAP 60 Series) and others that is more sensitive then a patch antenna and is capable of searching for satellites on a 360o 3D plain. This type of antenna contains four spiraling elements that are contained within a plastic case for protection and durability.
Selective Availability – Intentional random error distributed by the U.S. Government that can be added to GPS signal to degrade accuracy. SA is currently disabled.
Statue – The U.S. unit of measurement, such as: feet, Fahrenheit, & miles. Grid System Preference: Latitude & Longitude.
Triangulation – Uses the laws of trigonometry to determine the location of an unknown point. This is similar to Trilateration.
Trilateration – A method of mathematics for determining the intersection of three or more spheres when the center and radii's of those spheres are known. Ttrilateration is used is in GPS technology. The GPS receiver calculates the intersecting point of 3 or more satellites which in turn gives the GPS the coordinates of where the individual with the GPSr is standing on earth.
True North – aka Grid North, both are used interchangeably. Simply the direction to the North Pole, but the North Pole is not magnetic north. The difference between the two is called declination. Similar to grid north
Universal Transverse Mercator (UTM) – A global grid system that splits the earth into 60 zones, each zone of which is 6o wide. This system starts at the equator (0o) and a zone meridian (180o, International Dateline in reference to latitude & longitude) and uses letters of the alphabet along with eastings & northings. UTM stands for Universal Transverse Mercator. This system is popular for use on land. Unlike lat. & long., which projects imaginary grid lines on the globe. UTM projects section of the globe on a flat surface, like a map. Again there are 60 sections or zones in the UTM system that cover 6o each. This type of grid system starts with section 1 at 180o - 174o, continuing east to zone 60. Two other elements describe this system in greater detail; they are easting and northing values. Easting & northing values measure how far in meters, within the zone the reference point is. Eastings measure east/west and northings measure north/south. Ex. 18 T 363327 4591410 “Split Rock" on the Loyalsock Trail. This landmark is a cool rock that split over time creating crevasses between the rock. The neat thing about UTM is, you can compare the distance between two reference point by taking the difference of the two coordinates (along as they are within the same zone).
Latitude & Longitude
Universal Transverse Mercator
Military Grid Reference System
Universal Polar Sterographic System
Ordinance Survey Great Britian
Maidenhead Grid System
Questions or Comments?: Please feel free to email me, I would appreciate them, Thanks!
*Please remember, the information posted on this page and all other pages can & probably will change. I assume no liability for accidents happening to, or injuries sustained by, readers who engage in the activities posted on my entire website including links. Remember, you are responsible for your own actions, please understand conditions on the trail, in the woods or on the river can/will change due to mother nature. Please don't assume I know all there is about such topics, unfortunately I do not. I am just posting my travels and opinions experienced out in the wilderness. I encourage you to read further and look to reliable resources like the PA Game & Fish Commission and the PA DCNR. Thank You.