GPS For the Light Infantry Leader

1
Land Navigation

• GPS For the Light Infantry Leader

2
What is GPS

• A navigational system to determine location and
  velocity on land, at sea and in aircraft over the
  Earth
• A system your receiver is just one part of it
• Installed and operated by the USAF fully
  operational in 1995
• 28 satellites (incl. 4 spares), orbiting 22,200
  km up
• Satellites sent microwave signals with very
  precise time signals synchronization of several
  of these signals with the GPS units clock and
  triangulation gives a location on the surface of
  the Earth
• You can only see a few at a time due to the shape
  of the Earth at least 4 are required for a good
  location fix

3
What GPS is good for

• Indicates location on (or above) the Earth
• Tells time very precisely and accurately
• Indicates speed, direction, altitude
• Does most of this with great precision
• Reasonable accuracy location as good as a few
  feet with most modern hand-held units
• All units have some added features
• Waypoints
• Routes
• Tracks
• Dynamic heading/distance
• Moving map display

4
What GPS is not

• A compass the north arrow is (generally) only
  relative to the track when moving
• Always accurate or available certain conditions
  can degrade accuracy or cause total loss of
  signal, including
• Being indoors, or under any structure
• Terrain, including trees, mountains and ravines,
  buildings
• Space weather (e.g. solar flares)
• Sandstorms (due to static electricity)
• Geometric Dilution of Position sometimes, your
  satellites will be in bad positions, and accuracy
  will drop for several hours, by as much as a
  factor of 10
• Active jamming (loss of signal) or spoofing
  (showing false positions) by adversaries
• Also note that Selective Availability (S/A)
  allows the DoD to degrade performance of
  commercial units in wartime

• Some units do have built in real-time compasses,
  but these have their own limitations, and vary by
  device. GPS itself does not have a live compass,
  so understand the north arrow only counts when
  moving, and relative to the track
• If GPS precision is important for a mission,
  have the USAF Space Command contact for your
  theater run the GIANT program to tell you the
  best times.

5
Pitfalls Precision vs. Accuracy

• Precision vs. Accuracy A precise rifle groups
  well an accurate one hits the target. While both
  is best, accuracy is paramount.
• The GPS, like most electronic devices, implies
  great accuracy due to its display of data very
  precisely.
• Recognize the possibility and keep it in mind
  most modern GPS units will display an accuracy
  value. Use this, the number of satellites tracked
  and other behaviors to help determine how
  accurate the unit is reading at that moment.

6
Pitfalls Tool in the Toolbox

• GPS is a supplemental navigational tool, not a
  crutch
• Use GPS in conjunction with
• Compass
• Distance (pace or odometers)
• Terrain association
• Common sense
• GPS will let you down if you have poor landnav
  skills, or are getting poor results with other
  methods

7
Using your GPS

8
Setup

• Carry extra batteries know how to change them in
  the dark
• Read the manual some of these setup functions
  are complex or counter-intuitive
• Find a place to put it on your gear (should allow
  the antenna to see the sky best if it can do
  this all the time to speed its use, track your
  travel, etc.)
• Configure it to not beep, and be secure
• Set the grid to MGRS UTM will do, but avoid
  lat/long in degrees
• Set Datum. WGS84 is a good default, but look at
  your maps every time. You may have to change it
  in the field, so memorize how to
• Enable WAAS (EGNOS in Europe and MSAS in Japan
  are the same thing) for increased accuracy

The Garmin Rhino is a reasonably popular series
of handheld units that combines GMRS radio with a
GPS unit. It also can transmit position
information to other Rhinos in the area. This
should, of course, be disabled in any tactical
situation to avoid enemy interception. While
all ground units, and much air support, refer to
ground locations using MGRS, the USAF in general
uses Lat/Long. If you can set a secondary grid,
go ahead and have it set to Lat/Long, in DDMMSS.S
format, just in case. Know how to change it in
the field as well.
9
Pre-mission

• Mapping GPS units, especially, will benefit from
  use of software on desktop computers. With this,
  you may more easily load information into the
  unit.
• Plug the GPS into the PC, and load mission plan
  information into the unit.
• Load maps for the area if you have a mapping GPS
• Load waypoints and expected routes remember to
  use maps and be flexible, a few good points and
  routes are better than many cluttering up the
  display
• Review the GPS maps and compare to your issue
  printed maps, other information issued or which
  you have from previous observation. Digital maps
  have flaws and are often out of date Note the
  discrepancies so you are prepared for
  contingencies when you get on the ground
• Keep OPSEC in mind just like a printed map, use
  codenames for objectives. Do not store waypoints
  for rear areas, and other items not required for
  the mission

10
Using in the field

• Use GPS units in conjunction with compasses,
  distance measuring and terrain association
• Know what you want to get from the GPS unit
  before pulling it out do not stare at the screen
  while walking, or just hope it will tell you the
  answer
• Refer to the GPS unit for current coordinates,
  distance and bearing to waypoints, and to observe
  your recorded track
• Do not burden your decision making with
  technology-management or get possessive about the
  cool toy allocate the GPS and its tasks to team
  members

11
Field Use Exercises

• These may be performed anywhere there is suitable
  room and a GPS signal
• Ex Refer to GPS to confirm pacecount it may be
  useful to allocate the 2nd man in line the GPS
  for this reason
• Ex Use the track recording function to assure a
  good box-search in difficult terrain fill in
  gaps in the search so far
• Ex Set a deliberate waypoint (e.g. patrol base)
  use GPS functions to find distance/heading back
  to the base, then return using compass/pacecount
• Ex Set a hasty waypoint while on the march, such
  as a road intersection or observed enemy position
• Ex Confirm the actual location of a feature (as
  of the patrol base above) using all data sources
  (map, gps, terrain). Decide how to discard bad
  data if they do not all agree

12
Post-mission

• After the mission, do essentially the reverse of
  the pre-mission planning
• Do this as quickly as practical, so your memory
  can fill in gaps in notes, and while the
  information is still relevant
• Plug the GPS into the PC, and upload the units
  stored data into the computer
• Upload new waypoints you may have entered while
  in the field if short (or no) labels were
  allocated, refer to your paper notes to give them
  more useful labels for the future
• Upload track information to see the path you
  actually moved along compare this to your
  planned path and determine why it varied
• Compare this information to other notes and
  information obtained by other navigational
  techniques. Attempt to determine where you
  actually went and where you actually found points
  of interest. Even if you will not be travelling
  in this area again, someone else might more
  information is always useful