Map, Compass & GPS

Map, Compass & GPS
Wild flowers along Fall Creek on the way to the Green Lakes - Oregon

Sunday, April 19, 2015

GPS Vulnerability



An I-Team investigation revealed that a radio navigation station operating near Searchlight in southern Nevada was shuttered by the government in 2010, against the advice of top scientists. The station was later vandalized.
The LORAN station was part of a radio navigation network that could have served as an important safety net should the orbiting satellite system fail.
The LORAN radio navigation station in Searchlight was just one of two dozen similar facilities scattered around the country.
The decision to close the Searchlight LORAN and other valuable stations like it prompted some serious questions.
Interesting point of view.  Read the complete post here.

Thursday, April 16, 2015

Navigation Term of The Month

Declination

Declination is the angle measured between true north and magnetic north. Declination must be factored into all wilderness trips
Account for declination before leaving the trailhead.  I like to keep my navigation simple and personally use a compass that can be adjusted for declination such as the Brunton 8010G or the Silva Ranger.  Declination information found at the bottom of a topographic map is frequently out of date.  Check the web site www.magnetic-declination.com  for the current declination.

 “A compass is basically a magnet mounted on a pivot, free to turn in response to the pull of the earth’s magnetic field.  The housing protects the needle and helps you relate the direction in which the needle points to directions on the map and on the land.  A compass by itself can’t tell you where you are or what you are looking at but it can tell you about direction….”

Staying Found, The Complete Map & Compass Handbook, by June Fleming

NOTE:  June Fleming's book is probably available at your library.  It is a great read on land navigation.

Wednesday, April 15, 2015

Cascadia Tsunami Survival

The following AP article appeared in the Bend Bulletin.

By Jeff Barnard / The Associated Press 
          
    


GRANTS PASS — About 5,500 more people could survive a major tsunami hitting the Pacific Northwest if they just walk a little faster to higher ground after roads are knocked out, a new study shows.
The report published Monday in the Proceedings of the National Academy of Sciences looked at 73 communities along 700 miles of coastline in Oregon, Washington and Northern California. The area is considered most at risk from the next major earthquake and tsunami in the Cascadia Subduction Zone, where two plates of the Earth’s crust come together miles off the coast.
Emergency preparedness experts generally agree that after the quake and tsunami, most roads will be too damaged for driving, so people will have to walk to safety.
Geographers estimated 21,562 residents would not make it to safety if they walk slowly — at about 2.5 mph. But if they walk faster, at about 3.5 mph, the death toll drops to 15,970. About 70 percent of them would be in Washington, nearly 30 percent in Oregon and very little in California.

Wednesday, April 8, 2015

Ten Common GPS Myths

The U.S. Air Force's blog has a great post about 10 common myths related to GPS.   I've attached it below.  


WALLPAPER GALLERY
10 COMMON MYTHS SURROUNDING GPS
 By Brian Hagberg
50th Space Wing Public Affairs
The Global Positioning System, or GPS, has been broadcasting signals for nearly 40 years. During that time, a number of myths, misconceptions, conspiracies and falsehoods have been raised. Let’s examine 10 common myths surrounding GPS.
1. The U.S. military owns GPS
GPS is operated by the 2nd and 19th Space Operations Squadrons at Schriever Air Force Base, Colorado. However, the U.S. government owns GPS, and the program is paid for by U.S. taxpayers. According to GPS.gov, GPS receives “national-level attention and guidance from a joint civil/military body called the National Executive Committee for Space-Based Positioning, Navigation and Timing.” The committee is co-chaired by the Deputy Secretaries of Defense and Transportation.
 
2. The U.S. military has turned off civilian GPS signals for operational or combat purposes
Since being declared fully operational in 1995, GPS has never been deactivated by the military for its exclusive use during combat operations. There are millions of civilian users and monitors of GPS around the world. If the U.S. military turned off civilian GPS signals, even for a few seconds, those monitors would have made sure everyone knew about it.
The bulk of this myth stems from what’s known as selective availability, which allowed the military to intentionally degrade public GPS signals for national security reasons, most notably during Operations Desert Shield and Desert Storm. In May 2000, President Bill Clinton directed the government to discontinue use of SA, and this policy has remained in place ever since. President George W. Bush took the policy a step further in September 2007 when he announced that the government would procure GPS III satellites, which do not have the SA feature. Once these satellites achieve full operational status, SA will no longer be an option, thus eliminating this myth permanently.
3. Military GPS is more accurate than civilian GPS
The accuracy of GPS signals in space is the same for both military and civilian GPS, according to the GPS.gov website. The main difference, for the time being, is that military GPS operates on two signals, while civilian GPS operates on one. However, civilian users will soon have two new signals to operate on. In June 2014, a group of specialists from the 2nd and 19th SOPS, Space and Missile Systems Center, Air Force Space Command, the Department of Defense and Department of Transportation completed an upgrade to current GPS satellites allowing them to broadcast the L2C and L5 civilian signals. The signals are not yet fully operational, but once they are, civilian users will have access to the two signals as well.
Airpower meets space power as the U.S. Air Force Thunderbirds Demonstration Team soars in formation over Schriever Air Force Base, Colo., May 25, 2008. The flyby is a historic first for Schriever, which does not have a flightline. The Thunderbirds are in Colorado Springs in preparation for a demonstration at the U.S. Air Force Academy graduation May 28. (U.S. Air Force photo by Staff Sgt. Don Branum/Released)
4. The closer you get to a military base, the better your GPS signal will be
“So I’m sitting in a restaurant with my lovely wife and this guy at another table, the kind of guy (who) talks loud so everyone is aware he is an expert on whatever subject it is he’s talking about, starts talking about GPS,” said Lt. Col. Matthew Brandt, 2nd Space Operations Squadron commander. “My wife whispered to me, ‘He’s wrong, isn’t he?’ ‘Oh yes,’ I responded. ‘He’s way off.’ After a while, the guy boldly proclaims to the entire restaurant, ‘Of course, you know GPS always gets better the closer you get to a military base!’ and I promptly spit my drink across the table.”
As for being close to a military base, well, let’s just say that my car GPS has a hard time even finding Schriever AFB, let alone getting a signal boost when I’m there.
5. GPS resides only on phones, in cars and on hand-held display units
GPS is, and does, so much more than sit on your phone and wait for you to ask directions to the nearest coffee shop. GPS technology affects our lives in more ways than we could possibly imagine, from banking systems and financial markets to communications networks, power grids, weather forecasting and environmental protection efforts. GPS is everywhere (and those are just a few of its civilian uses). GPS touches so many lives on a daily basis that the International Astronautical Federation presented GPS with the IAF’s 60th Anniversary award because they stated, “GPS is the space program that touches and aids more humans every minute of every day in every corner of the globe.”

6. The government gave 2010 census data collectors GPS-enabled handheld computers as part of a secret plot to take away our liberties
Census data collectors have been mapping home locations for a while now, and they just got an upgrade from paper and pencil to computers in 2010. “The exact geographic location of each housing unit is critical to ensure that when we publish census results for the entire country, broken down by various geographic areas ranging from states, counties and cities, to census blocks, we accurately represent the data for the area in question,” says the U.S. Census Bureau’s website. The site goes on to say an incorrect allocation of information to the wrong geographic area would result in inaccurate data to two areas, which could affect the distribution of funds to state, tribal and local governments.

7. The government uses GPS satellites to track/spy on us
The issue with this myth is, of course, the fact that the GPS device used in cell phones is a receiver, not a transmitter. Thus, your phone is not constantly transmitting your position unless you continue to use the “Hey, here’s where I am!” feature through various social media platforms or applications.

8. GPS won’t work if it’s cloudy or there is bad weather
People tend to correlate GPS with what they know about satellite television service, which is notorious for losing a signal during times of adverse weather conditions. The GPS version of “clear view of the sky,” simply means the receivers need a signal path clear of obstructions such as mountains or dense canopy, according to gpsreview.net. This belief seems to have lost traction through the years as GPS technology became more widely available
.
9. If you get lost, blame the GPS!
Some people have taken this one to the extreme. A Nevada couple heading home from a trip to Oregon in 2009, followed their GPS down a service road, got stuck in the snow and was stranded for three days before being able to get a cell phone signal. The driver said he was simply following the directions from his GPS. This prompted some members of the media to write stories blaming either aging GPS satellites or a weak signal for the device leading the couple down the wrong road. The Air Force felt compelled to set the record straight as the Air Force Space Command Twitter account, @AFSpace, sent out this message: “While we do not want to speculate on what caused the couple to get stuck in the snow; the cause was not due to GPS signal.”
“The signals that are coming down are very strong and healthy, said an Air Force spokesperson at the time. “In the event one of our satellites fails, we can immediately have another one up to have the full coverage that we need.” Even though there are 30-plus GPS satellites in orbit, only 24 are active at any given time. This allows for immediate replacement of signal if an issue arises with one of the satellites. Users should also remember the satellites only provide the signals, it’s up to users to keep devices updated with current maps and information.
10. GPS navigation systems will always pick “the best route”
Most navigation systems will allow users to choose between the shortest route, quickest route, scenic route or whether to include toll roads. These are all convenience services, but none of them state they are offering the “best route.” That’s probably because the designers are busy having the same discussions that have been occurring in gas stations and street corners for years, namely trying to determine exactly which is the “best way to get to…” One thing current navigation systems can’t account for is “local knowledge” of an area. GPS doesn’t know that school lets out early every other Thursday or that everyone takes Main Street to avoid rush hour traffic. These are things people need to consider when determining which route to choose.
A special thanks to 2nd SOPS members, Lt. Col. Matthew Brandt, Capt. Achille Aloisi, Capt. Douglas Ruyle and Tech. Sgt. Abifarin Scott for contributing to this list.
 

Backpacking Gear Myths

Philip Werner at SectionHiker has a interesting post about:

10 Backpacking Gear Myths
It’s amazing how some backpacking gear myths persist, even when there’s ample evidence to the contrary. Here are my favorites.

Tuesday, April 7, 2015

GPS Tracking Technology

From the UK's GPSTraining (www.gpstraining.co.uk) email update:

"Did you know that the U.S. government is placing a high priority on developing a more reliable real-time position tracking technology whose signals won’t disappear in blind spots
and can’t be jammed after finding that GPS can be unreliable in certain situations?  DARPA an agency of the US Department of Defence recently said it was researching “radically” new technologies to deliver more advanced position- and navigation-tracking systems that are more reliable and accurate than the current GPS System.  Don’t expect developments any time soon but remember that it was the US military that developed the GPS System; our guess is that this is a serious project."

Monday, April 6, 2015

Sighting With a Magnetic Compass



Sighting with a compass is an important skill that can determine direction to an object or help the hiker locate and identify his position in the backcountry.

A compass is an important part of the backcountry navigator’s kit.  The use of Global
Positioning System (GPS) receivers has simplified navigation to an extent but the knowledge of how to use a compass is still important; do not underestimate this skill.  

“A compass is basically a magnet mounted on a pivot, free to turn in response to the pull of the earth’s magnetic field.  The housing protects the needle and helps you relate the direction in which the needle points to directions on the map and on the land.  A compass by itself can’t tell you where you are or what you are looking at but it can tell you about direction….”
Staying Found, The Complete Map & Compass Handbook, by June Fleming

Sighting with a compass allows the hiker to determine the direction to an object such as a mountain peak.  The compass direction to an object is known as the “bearing” or azimuth.   Bearing is the more common term in outdoor recreation and is a term used heavily in GPS navigation.  For example, if a mountain peak is due north of you, the bearing to the peak is 000° (read as zero zero zero degrees.)

Sighting with a compass allows the hiker to do several things.  First, sighting on a distant object can provide direction to that object and repeated sightings can provide course corrections along the way.  Secondly, with several sightings on different objects a person’s position can be triangulated. 

This article will focus on using a standard baseplate compass such as the two examples pictured below.  (The lensatic and military compass will not be discussed.)


Figure 1 Two examples of good baseplate compasses.

Key features of the two compasses (above) include:

  • They are declination adjustable
  • Liquid filled housing to dampen the magnetic needle’s movement
  • 2° increments on the bearing dial of the compass housing
  • A clear baseplate of adequate size with map scale information and a small magnifier.
The picture below offers a quick review of the components of a baseplate compass.






To sight or take a bearing do the following:

  1. Using the owner’s manual, adjust the compass for declination.
  2. While holding the compass at waist level, turn squarely towards a distant object.  Hold the compass so that the direction of travel arrow points directly at the object. (Point the direction of travel arrow away from you; perpendicular to your body.)









  1. While holding the compass, turn the compass housing (the dial) and align the orienting arrow (engraved in the rotating housing) underneath the red magnetic needle.













  1. In this example, the compass has been adjusted to a bearing of 011° degrees.  The bearing data is found where the direction of travel arrow intersects the compass housing.
At this point the hiker can walk towards the object (e.g., mountain peak, building) on a bearing of 011°.

If the hiker needs to determine his position, the next step is to triangulate using three bearings.  In a “nut shell” this means that bearings to three clearly identifiable features are used.  Ideally, objects that have a bearing separation of 30° – 60° will be used.  Good bearing separation provides better fixing information and plots on the map cleanly.  The bearings are then plotted on a map and where the three lines cross is the hiker’s location.  This complete process is called triangulation.

The following are suggestions for triangulating a position in the back country.
  1. Identify three distinct objects to sight on.  Note that the objects need to be on the topographic map (topo) of the area.  I recommend carrying a forest service map (or something similar) of the area in addition to the topo just incase the objects are too far away.
  2. Orient the topo using the compass.  Orienting the topo means that the map’s left or right border is pointing to true north or 000° degrees true.  See “Orienting a Map” for more information.
  3. Sight on an object such as a mountain peak or church spire.  (Note that not many objects in the backcountry are so distinct and crisp.  Do the best with what you have.)  Ensure the direction of travel arrow is pointed towards the object.
  4. As discussed earlier, turn the compass housing until the orienting arrow is directly under red magnetic needle.  Do not move or rotate the compass housing, keep the new bearing in place.
  5. At this point, and while plotting the bearing on the map, the compass will now be used like a protractor.
  6. Lay the compass on the map with either the top left or right corner of the baseplate on the landmark.  This will be a pivot point while aligning the compass.
  7. With the edge of the baseplate in position, rotate the compass (swing) left or right until the N (north) of the compass housing aligns with map North (the top of the map.)  What is even better, with the map oriented to north, as the baseplate is rotated, the red magnetic needle will swing back into position on top of the orienting arrow. 
  8. Draw a line (along the baseplate) from the object to your approximate area.
  1. Repeat the process two more times.


  1. Ideally the three lines will intersect in the immediate area but because of compass error and human error the point of intersection maybe spread out.  Still, triangulation will put you in the ballpark.  Use terrain association to help narrow down your position.