ARMY TM 5-6675-308-12
MARINE CORPS TM 08837A-12/1A
NOTE
Positioning Satellite NAV STAR (GPS). Accuracies
are currently 25 meters spherically. Eventually 24
hours coverage will become available providing the
only to the solid state memory using the
user with uninterrupted coverages. The user is cau-
newer program containing GPS.
tioned when using GPS data. The various agencies
controlling GPS can misdirect through various tech-
niques and cause positioning errors up to 200 meters
vehicle. Helicopters are used in special situations, e.g., great
and perhaps even more. Some receivers have
distances between survey points, survey points inaccessible to
embedded cryptology to decode the selected errors,
a land vehicle, or when speed is of paramount concern.
some do not. Reference the receiver manual for the
Because operations in a land vehicle or helicopter are nearly
receiver in use to determine applicability in those
the same, complete procedures are given only for a land
matters. The PADS software has been enabled to
vehicle mounted PADS. Transfer between a vehicle and heli-
accept manual entries of GPS data with correspond-
copter is described.
ing changes to accommodate the possible random
errors associated with GPS. The operator will be
PADS requires horizontal and vertical position
a.
informed via the mark table whether GPS, differen-
information to enable it to determine accurate posi-
tial GPS or survey control was associated with the
tion, azimuth and elevation. Initialization data can
survey mission, and of those marks/updates uniquely
vary from update data. This was designed into the
associated.
software to allow system alignment to be performed
in an area, using less accurate data (map spot, etc.)
d.
If known survey control is unavailable or is suspect of
than the data used to update the system. The update
being in error, PADS should use GPS data to update.
data should be the exact coordinates and elevation
e.
PADS update is performed in two distinct phases and
relative to the grid or map being used for the survey.
is isolated from one another. The first in sequence is
Any position or elevation error entered during the
horizontal position. When this has been accepted, the
update will be carried by the PADS throughout the
elevation phase initiated automatically for conve-
mission.
nience. These have been combined to follow one
b.
Small position errors will not affect the azimuth
another, but can be performed individually if one con-
determination accuracies as long as the target is on the
trol data is suspect. Therefore, the operator can be
same map or grid. If two grids or maps are used, posi-
performing two consecutive (if desired) updates,
tion errors may have a greater impact on the target
using GPS/DIFF GPS and/or SCP.
solution.
PADS Mission Procedure. Normal operating
The initial position data typically has been obtained
c.
procedures are summarized in table 3-3.2. The mission be-
from local survey control, DMA maps, local road
gins with pro-tumon checks and services, followed by initial-
maps among a few, aided by local landmarks such as
ization. Next, PADS is updated, using the position and
mountains, streams, etc. Ocean and desert locations,
elevation update procedure. PADS then performs a series of
lacking in obvious landmarks or other defining marks
marks, where position, elevation, and azimuth are recorded.
present a difficult, if not impossible situation in deter-
Update, data recall, and shutdown completes the mission.
mining, rough present position. Currently, another
means of obtaining relatively accurate three dimen-
mission phases are explained in detail. If a malfunction oc-
sional position is available. This is known as Global
curs, refer to table 4-2, Troubleshooting.
Change 3
3-36.1
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