1. Compass and Pacing
And GPS

2. Orienteering and surveying
Determine area of land
Locate boundaries on map
Plot trails
Follow directions to a point
How accurate is needed?

3. Compass
Today’s liquid-filled field compass, when held level and read properly is accurate to the nearest 2 degrees

4. Staff Compass More stable
Bubble level to insure horizontal orientation
Larger circle with finer scale
Accurate to nearest .5 degree

5. theodolite Tripod mounted for maximum stability
Dual axis bubble levels
Large scale with magnified optics
Also measures vertical rise/drop by sighting the same height on a range pole held at the target
Most accurate non-electronic method
Barely used today

6. Laser theodolite Sights at reflector at target
Does the horizontal distance correction for you

7. Gps surveying Does not require line of sight between antennas
Communicate wirelessly
Gets X,Y,Z coordinates of stations just subtract the height of the unit

8. The Compass

9. I want to go NW
First rotate the dial until it points the way you want to go
Then rotate your body until the north arrow points north
Walk in the direction of the arrow

10. Azimuths and Bearings

11. Compasses and Maps

12. Compass App

13. Magnetic Declination
The declination is given as e.g. "15 degrees east". When you look at the figure, you can pretend that plus is to the right, or east, and minus is to the left and west. So when something is more than zero you'll subtract to get it back to zero. And if it is less, you'll add. So in this case you'll subtract 15 degrees to the azimuth, by turning the compass housing, according to the numbers on the housing.

14. Additional considerations
Compasses work underground unlike GPS
Local magnetic sources can cause errors
Can take a ‘backsight’ on where you came from to confirm that it is 180 degrees off the traveled azimuth.
Compass and Pacing is a conclave competition.

15. Pacing
1 pace equals the natural stride of both legs starting and ending with the same foot.
Can and should practice often – get consistent.
Recognize that is varies by slope, must compensate.

16. Gunter’s chain
In 1620, the clergyman Edmund Gunter developed a method of surveying land accurately with low technology equipment, this was 66 feet long and from the practice of using his chain, the word transferred to the actual measured unit. His chain had 100 links, and the link is used as a subdivision of the chain as a unit of length.
In countries influenced by English practice, land plans prepared before about 1960 associated with the sale of land usually have lengths marked in chains and links, and the areas of land parcels are indicated in acres. A rectangle of land one furlong (10 chains) in length and one chain in width has an area of one acre. A square that is 1 acre in area is roughly 200 feet on a side (208.7’)
It is sometimes suggested that this was a medieval parcel of land capable of being worked by one man and supporting one family.

17. Gunter’s chain

18. Chains Conversions: 1 chain (1 ch) = 66 ft (100 links)
4 poles or rods = 1 chain
1 tally = 5 chains = 330 ft
20 chains = ¼ mile
80 chains = 1 mile
1 mile = 5280 feet
1 acre = square feet
640 acres = 1 section (square mile)
36 sections = 1 township
1 acre = 10 square chains
40 acres = 20 chains x 20 chains
1 section = 80 chains x 80 chains

19. ‘throwing’ the chain

20. Hipchain

21. Metes and Bounds Deed Surveys
Metes = distance to ‘turn’ of boundary
Bounds = direction
Historically the original 13 colonies and their derivative states (from the British surveying)
Problems:
Described boundary points often change
Doesn’t work well in homogenous landscapes
Corrected for declination?
Year surveyed?

22. Public Land Survey System

23. PLSS terms dimensions (miles) (mile2) area (acres) (m2) (km2) notes
Quadrangle
24 by 24
576
368,640
1,492
  Usually 16 townships
Township
6 by 6 36
23,040 93
   Usually 36 sections
Section
1 by 1 1
640
2.6
Half-section
1 by 1⁄2
1⁄2
320
1,294,994
1.3
Quarter-section
1⁄2 by 1⁄2
1⁄4
160
647,497
Half of quarter-section
1⁄2 by 1⁄4
1⁄8 80
323,749
Quarter of quarter-section
1⁄4 by 1⁄4
1⁄16 40
161,874

24. What is GPS?
Global
Positioning
System

25. History of GPS Department of Defense developed for navigation
Standard positioning service (public uses)
Precise positioning service
Launches began in 1970s
Full operational capability in mid 1990s
‘Selective Availability’ turned off 2000
Degraded accuracy to ~100m

26. GPS system segments Space segment – (satellite life = 10 years)
Several generations of satellites in use now
Control segment
User segment

27. Space Segment
24 satellites with spares in 6 orbital planes (4 in each)
~12,500 miles elevation
55 degree inclination
Each one circles Earth every 12 hours (7000 mph)
At least 4 visible at every point on the earth at all times

28. Control Segment Master Control Station (MCS) in Colorado
5 Monitoring stations
Ground control stations (Ground Antennas)
Unmanned
Enable MCS to control the satellites

29. User Segment Antenna Receiver Base map
Record tracks, waypoints, distance

30. How does it work? Triangulation
Need D+1 satellites to determine position = 2D needs 3 satellites, etc

31. Sources of error ionosphere
Dual frequency mode of more advanced receivers corrects

32. Sources of error - Satellite geometry
Geometric Dilution of Precision (GDOP) – the higher the value, the poorer the measurement (very good = <4, bad = >6)

33. Sources of error multipath

34. How accurate? Recreation grade = ~8m Mapping grade = <1m
Survey grade = several cm
Accuracy versus Precision
Accurate measurement versus true location
Precise measurements close to each other

35. Improving accuracy – 2 to 5 M

36. A word about GLONASS
GLONASS (GLObal NAvigation Satellite System) is the Russian military equivalent of the US GPS system. After launching in 1982 full capacity was reached in 1995 but allowed to decline until 2001, Under Putin, restoring this system was made a priority. In 2010 Russian coverage was restored and by 2011 global coverage was achieved. In 2015 smartphone chipsets have been enabled to receive GLONASS signals.
GLONASS satellites orbit make them especially suited for usage in high latitudes (north or south). US GPS coverage is better at lower latitudes, thus supplementing GPS signals with GLONASS signals in Alaska and Canada is advantageous. In fact, as of 2015 the GARMIN GPS that the USFS uses now is required to support both.
By utilizing both systems, accuracy in mountainous regions in high latitudes is greatly improved and position fixes are quicker with more satellites available.

37. China has BeiDou – second edition called COMPASS by 2020
While on the topic…
Other countries have or plan to have their own navigation system in place
France has DORIS
China has BeiDou – second edition called COMPASS by 2020
India has IRNSS (regional)
The EU plans to have Galileo by 2020

38. Cell Phone GPS Most GPS in cell phones do not use satellites.
They triangulate via cell towers whose locations are precisely known.
The signal is not line-of-sight so they can work indoors.
Does not work where limited cell service exists (like many forests).
Accuracy varies (< 10 m to ~100 m).

39. Area Determination Compass and Pacing Map with dot grid
Cut and weigh method
GPS
ArcGIS or similar mapping software