Positioning Systems
Google Maps
http://maps.google.com enable you to seek locations based on geographic names.
http://www.google.com/history
enables
iTouchMap displays Latitude/Longitude on Google Maps.
Latitude sounds like "flat" as in going between East and West.
The lat in Latitude reminds us that its goes lateral (sideways).
Since the latitutde/longitude coordinate system was developed by the British Navy
at Greenwich (London),
zero degree 0° latitude starts there, at the Prime Meridian.
The 360 degrees to a lateral circle are divided in a positive and negative 180 degrees.
Each one degree of latitude is just over 69 miles, or 111 km
of the earth's 25,000 mile circumference.
- The Eastern-most point in the US is near Bangor, Maine at 69 W.
- Honolulu, Hawaii is the Western-most point in the US at 157 W.
- Anchorage, Alaska is at 149 W.
Longitude contains an N for North (not in the word latitude).
At 45 degrees N or S of the equator, one degree of longitude is about 49 miles.
But as you move north or south of the equator,
the distance between the lines of longitude gets shorter.
- The Equator is 0 degrees.
- The North Pole is 90 degrees North. South Pole is 90 degrees South.
- Northern Arctic circle (66.5 degree North)
- Southern Antarctic circle ( 66.5 degree South)
- Tropic of Cancer ( 23.5 degree North)
- Tropic of Capricorn ( 23.5 degree South)
- Greenich is at 51.5° North latitude.
- The "48th Parallel" in history is a L____ number.
For additional precision, a coordinate can be broken down into minutes (') and then seconds (").
Each degree has 60 minutes. Each minute has 60 seconds. Each seconds can be further divided into tenths, hundredths, or even thousandths.
Sundials and Sextents
A GPS is not needed to know which direction is North.
Yes, you can find the North Star on a cloudless night.
Yes, you can find the North Star.
Star Systems
because there is a precess
of 23.5 degrees from a theoretical eliptic pole,
such that a complete rotation takes 25,800 years.
This torque is created by a whobble caused by the bulge at Earth's equator.
What enabled Columbus and other sailors in his time to sail the oceans and "discover"
new lands is the ability to navigate using the pattern of stars and the sun.
Sundials do this.
The specification of position of stars from Earth is described by
Michael Richmond
This time-lapse photo show how stars in the Northern Hemisphere
revolve around the "North Star" Polaris
at the handle end of the "Big Dipper" constallation.
But where the Celestial Pole points is only temporary
H. A. Rey's book
The Stars: A New Way to See Them
(1976: Houghton Mifflin)
illustrates shows that people living in 500 BC see stars rovolving around
the star Kochab.
Astronomers measure
(from the Celestial Equinox radiating from earth's equator)
the proper motions of stars in "arcseconds"
or "milliarcseconds" per year
vertically in Right Ascension (RA) and horizontally in Declinations (Dec.).
Jamie Love's description of precession
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Paper Maps and Magnetic Compass
The compass is based on magnetic fields inside the earth.
The trouble is that the strength and alignment of magnetic fields differ widely,
especially over iron mines.
Those who use map and compass add lines to Topo maps.
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Microsoft Maps
Microsoft Streets and Trips (SnT) is the entry-level consumer edition.
It covers US and Canada.
Microsoft's AutoRoute covers the streets of Europe.
Full price for it at Staples is $39, or $69 with a GPS USB device.
But I lose the GPS device often enough that I need to buy it for
$50 online on Amazon.
Microsoft's
accessories site.
The $299
Microsoft MapPoint alternative edition provides "business" features
like export to Excel.
SnT is limited to importing Excel but not export because Microsoft's
TIP:
Unlike maps provided on mobile phones, an internet connection is not needed
for these products installed on desktop Windows 7/Vista/XP.
Its maps load into the larger hard disk on laptops from the DVD that comes with the product.
The down side of course is that updates need to be purchased.
To keep up with changes, Microsoft publishes annual editions. The 2013 edition was available July 2012.
On top of the DVD,
DOWNLOAD:
Get and load waypoint pushpins, such as the 9+ MB
Points of Interest Mega file various hobbyists update for free use.
It still doesn't match the information shown on Google Maps.
But it contains many points of interest that can save you money and hassle:
- Accident black spots to avoid.
- Presidential libraries, hot springs, waterfalls
- campgrounds, RV parking at Walmarts
- Stores travelers frequent: Home Depot, Northern Tool, Bass Pro Shops, Cabellas, Trader Joes
- Lower priced fuel at truck stops like Flying J, Kroger, Loves, Murphy as well as fuel at
- Membership stores with gas: Costo, Frys, Smiths, Walmart.
BLAH:
Churches are missing from the file.
The POI file is not easy to use. The procedure for first-time setup:
- After download, open Windows Explorer and navigate to where .est files are stored.
That is typically My Documents.
- In 2009 and earlier versions, there is a Templates folder which the program goes to
for the default template
file when File > Open is invoked by the user.
- But there is no such folder in 2013 version. So from the zip folder drag and drop the template among the .est files.
- Open a second instance of the program. Your workstation may not have enough memory for this.
- Click on the help flags and icons and right-click to cut them.
- Within 2013 editions right-click on specific groups to show, then later hide each group.
Within prior editions, copy individual icons and paste
- The customer icons are rather big, which is good at high levels of zoom.
But this requires one to zoom in to read road names under the icon.
Trip Planning using Microsoft Maps
TIP:
The sequence of my approach to (obsessively) planning out a trip:
- Guidebooks help to provide priority of why I'm there:
If it's an event, I would plot the event site first, then surrounding points of interest such as
Museums or views or places to eat.
- Sunsets can be a special time for landscape viewing,
so I try to be at a good place to enjoy it,
such as a vista, especially in a restaurant or hotel with a view.
It's also not a good idea to be driving when the sun can get in people's eyes and when animals are out to feed.
QUESTION: To find the time of sunsets?
- Destination restaurants on Yelp, Zagat, Gayot, etc.
may alter my lodging plans since its wise to avoid too much driving after a meal.
- However, the availability of lodging does have impact. So it's a back-and-forth process.
BLAH:
Scheduling requires a few tricks.
- To stop for the night, right-click on a route icon (yellow box) to set schedule stop for 12 hours.
- To avoid changes to my schedule being changed automatically if a default option is changed,
I manually set each starting time to a custom time like 9:01.
- Set the default Start Time each day early (like 5 am) in menu Route > Route Options.
- Create a duplicate item to set the Starting Time each day.
- Once I have an inital schedule, I then adjust the sequence of locations.
- TIP:
It's wise to allow extra time to stop at interesting spots on the spur of the moment,
or for traffic delays.
- If I am using a rental car or have to drive long distances, to avoid the stress
I figure out ahead where to fill up on gasoline.
- When crossing time zone boundaries (such as going between Arizona and another state)
I click on the road near the border to add a location, then rename it to say change time zone.
- TIP:
Avoid clicking on the name of a town because that usually routes to a weird place.
Instead, get a general understanding of the location, then create a location by right-clicking on a road.
TIP:
Tactics I've found useful:
- BLAH:
The program does't show the direction of travel.
So to avoid confusion, for a complex itinery I use separate files for going into and out of a destination.
- QUESTION: To transfer a route item from one est file to another?
- I keep a scraps.est file to hold locations that are possible alternatives
not on my planned route, but helps me save time from looking them up.
- Unlike other Microsoft programs, pressing F2 does not allow editing. Instead, right-click and select Rename.
Copy the text before dragging yellow squre icons across the map.
After the move rename and paste the text.
Even though my mobile device can't hold the whole DVD,
supposedly I can transfer a limited number of specific maps to my mobile phone's SD card.
BLAH:
I wonder why there is a "Send to Mobile" button if its greyed because upgrade to MapPoint is needed to use it.
REFERENCE:
msstreets.com is the Streets & Trips team blog.
Quick Keys
Zoom In = Ctrl+Z
Zoom Out = PgUp
Zoom In Max = End
GPS Pane = Ctrl+A
Driving Guidance = Ctrl+B
Nearby Places = Ctrl+D
Import Data Wizard = Alt+V, Ctrl+I
Legend = Ctrl+G
Show in MSN Virtual Earth = Ctrl+H
Search Internet = Ctrl+K
Toggle Route Planner = Ctrl+G
Map Style Toggle = Ctrl+M
Map Style Toggle = Ctrl+M
Save = Ctrl+N
Open = Ctrl+O
Print = Ctrl+P
Start GPS Tracking = Ctrl+Q
Route Planner = Ctrl+R
Save (no confirm) = Ctrl+S
Directions = Ctrl+U
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Global Positioning Satellite Technology
Each major superpower each has their own set of satellites.
- China has their BeiDou Satellite Navigation System
- Russia has ...
- US has the NAVSTAR (NAVigation Satellite Timing and Ranging) satellites
The Samsung Electronics' Galaxy Note 3 was the first smartphone to incorporate all 3,
using the IZat location tools for Qualcomm chips inside them.
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Global Positioning Satellite Internals
GPS receivers display a waypoint -- a specific position on the earth -- by
interpreting signals from a constellation of 24 NAVSTAR (NAVigation Satellite Timing and Ranging)
satellites put up by the US Dept. of Defense.
The satellites circle the earth every 12 hours.
Waypoints (WPS) are based on the UTM (Universal Transverse Mercator) projection
of the world defined by the
U.S. National Imagery and Mapping Agency (NIMA).
For example,
where actress Eva Gabor is buried in Westwood Cemetary in Los Angeles: Longitude 34.05.880 N,
Lattitude -118.44.145 W is equivalent to this GPS coordinate:
“11S" is equivalent to a 100,000-meter square area between Longitudes -120 and -114 degrees West and
Lattitudes between xxx and xxx degrees North.
“11" specifies a horizontal East-West location
on this grid which horizontally divides the 360 degree circumference of our world into increments of 6 degree each for
60 Zone Numbers, beginning half way around the world from the “prime meridian" near the British Royal Naval Observatory near London suburb of Greenwich, England.
“S" specifies a North-South location among
grid increments equivalent to 8 degrees above and below the equator.
The 20 zone Designations go alphabetically from “C" at the South Pole (-80 degree lattitude),
through “N" at the equator (zero degree lattitude),
to “X" (+80 degree lattitude) at “True North".
“I" and “O" are excluded to avoid confusion.
“0123456" is the Easting value of 12.3456 meters.
Using the NAD 27 datum,
a central meridian at the middle of each zone is assigned an easting value of 500,000 meters.
Easting values to the west of this central meridian are less than 500,000 meters (yards);
to the east, more than 500,000 meters.
“3772456" is the sample Northing value of 3777.456 meters.
Positive northing values measure the distance Northward from the equator.
Negative northing values measure the distance Southward from the equator.
To avoid confusion, UTM maps do not display digits after the decimal point and highlight the last two significant digits.
An Easting of 3772.456 appears as 3772.
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Waypoints from other famous spots:
| Location | Parallels of Lattitude Degrees | Easting Zone Number | Northing Zone Designation | Meridians Longitude Degrees |
|---|
| Royal Naval Observatory, England | 0 | 31 | U | 48 N |
| Los Angeles, CA, USA | -118.44.145 W | 11 | S | 34.05.880 N |
| Cairns, Queensland, Australia | 144 E | 55 | K | -24 S |
Search the GNIS database of all names USGS uses on maps.
To calculate the exact distance between two coordinates (LAT1,LG1 to LAT2,LG2): The simplest but least accurate approximation method is (in BASIC):
D = 69.1 * SQR[ (LAT2-LAT1)^2 + 0.6 * (LG2-LG1)^2 ]
One degree of longitude or latitude is equal to 69.1 miles.
The most accurate calculation uses spherical geometry's arccosine function
after converting numbers to radians by dividing 180/pi — the constant C=57.3:
A = ( sin(LAT1/C) * sin(LAT2/C) ) + (cos(LAT1/C) * cos(LAT2/C) * cos(LG2/C - LG1/C)
D = 3959 * atn( sqr(1-A^2) / A )
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Map Grid Overlays
“7.5 x 15 Minute Quads" (1:25,000 scale) maps created by the
USGS (US Geological Survey) with UTM grid markings.
Download this PostScript file and print the overlay on acetate film
A large region of several states are shown at scales of around 1:580,000.
Metro areas are shown at around 1:200,000.
City maps are shown at views of around 1:150,000, with some historic and downtown areas shown at around 1:14,000.
Accuracy
When civilians first used GPS “Standard Positioning Service" signals,
DoD imposed Selective Availability (SA) accuracy of about 100 meters (110 yards) radius.
This means that the receiver could actually be anywhere within 200 meters of a given GPS coordinate.
As of May 2, 2000 SA IS OFF, improving average EPE (estimated Position Error) to 5-15 metres.
GPS Elevation readings are several times less accurate.
Also, each GPS satellite broadcasts a channel at frequency L1 (1575.42MHz) and L2 (1227.6 MHz) .
The more channels a GPS receiver can read, the more accurate its readings.
Readings may take several minutes, require a clear view of the sky with adequate
Mask Angle -- the minimum acceptable satellite elevation above the horizon to avoid blockage of line-of-sight.
A receiver that reads 12 chennels in parallel is quicker than a receiver which reads 8 channels in sequence (i.e. multiplex mode).
Differential GPS (DGPS) receivers use fixed land-based beacons maintained by the Coast Guard for 3-5 meter accuracy.
Accuracy within 3 meters comes from receivers which read differential signals from
FAA's WAAS (Wide Area Augmentation System) satellites over the equator, which broadcast adjustments needed to compensate for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere.
These adjustments are calculated by
25 ground reference stations across the United States.
Similarly, the Japanese have their Multi-Functional Satellite Augmentation System (MSAS),
Russians have their Global Navigation Satellite System (GLONASS).
The European Space Agency (ESA)
plans to have, by 2008, the Euro Geostationary Navigation Overlay Service (EGNOS) project known as Galileo,
30 satellites orbiting at 24,000 kilometers about the earth,
guaranteeing accuracy within 4 meters.
The Differential “Precision Positioning System" used by the military is most accurate.
The BlackJack system, delivers accuracy of 2 to 3 centimeters.
The accuracy of GSP can be improved by using a grid of them.
USC is using this technique to detect earthquakes in Los Angeles and elsewhere.
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Campmor.
Get Your Bearings
Many GPS receivers can log waypoints to determine the direction you've been traveling.
But this eats up batteries.
So many people also use a regular magnetic compass (
adjusted to magnetic decliations) to compliment the GPS.
Learn to use a compass at
Kjetil's Compass Lesson.
Trivia 
Earth and Mars have virtually identical spin axis tilts at about 23.5 degrees.
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Using GPS NMEA Raw Data
Raw GPS data issued by modern GPS devices follow a standard format defined by the
NMEA (National Marine Electronics Association).
Among the over fifty kinds of comma-delimited "sentence" issued by a GPS device,
the "Recommended Minimum" sentence is the most commonly used. Here is an example from
Jon Person's
tutorial on how Visual Studio.NET program can intrepret GPS data such as:
$GPRMC,040302.663,A,3939.7,N,10506.6,W,0.27,358.86,200804,,*1A
This one sentence contains nearly everything a GPS application needs: latitude, longitude, speed, bearing, satellite-derived time, fix status and magnetic variation.
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Decimal versus Radian Coordinates
Databases generally store coordinates in a decimal degrees floating point number rather than separate
degrees/minutes/seconds integers.
To convert from decimal degrees such as 45.63248 to degrees/minutes/seconds:
- Subtract 45, leaving only the decimal .63248. Keep
45 for later reference.
- Multiply by 60, to obtain 37.94880 – 37 is the
number of minutes; 37 then will follow 45 degrees.
- Subtract 37 to leave only .94880.
- Multiply by 60 once again to obtain 56.92800, and round
to 57, which represents the seconds.
- This yields 45 degrees, 37 minutes, 57 seconds.
To convert to decimal degrees from degrees-minutes-seconds such as 45 degrees, 37 minutes, 57 seconds:
- Begin with 57 seconds and divide by 60 to obtain .95000.
- Add the 37 minutes to yield 37.95000.
- Divide by 60 once again to obtain .63250.
- Add the 45 degrees to obtain 45.63250.
- CAUTION: Notice that rounding less than one-tenth of a second changes the conversion by .00002 degrees.
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GPS (Global Positioning Systems)
