Extended multichannel radio systems usually follow a zigzag course,
since the terrain seldom permits a straight line of relays. This may
result in some relay hops being less than the optimum range of the
equipment.
Obviously, straight-line siting reduces the amount of
equipment and support required.
However, it sometimes causes
assignment
problems
because
of
"overshoot."
Signal
overshoot occurs when the signal from one terminal continues beyond
its destination and reaches another site within the system with the
same frequency assigned.
There are several methods for selecting site locations. You may
use
any method, or a combination of several methods.
When there
is
rolling terrain or other areas where scatter or reflection of
the
signal may cause problems, specific locations of each terminal
and
relay station become critical. The following considerations will
aid
you in selecting the best possible site.
a. Siting by Altimeter and Photographs.
When you do not have
accurate contour maps available for siting, the altimeter of an
aircraft may provide you with a profile for a proposed signal path.
Readings taken of significant features of the terrain can be plotted
on the 4/3 Earth Profile Chart, Department of the Army (DA) Form
4219. You use this data, just as with contour maps, to profile your
system.
Aerial photographs are useful in identifying roads, power
lines, or other details that may affect the choice of the site.
b. Field Inspections. Maps and photographs provide adequate data
to make tentative site selections.
However, no matter what method
you use, an on-the-spot inspection provides the most accurate data.
The on-the-spot inspection often reveals problems that would not be
apparent from other data.
Additionally, if you have portable beam-
antenna equipment, you may make a signal strength check between
proposed adjacent sites.
c. Site Accessibility. One of the most important considerations
for site location is site accessibility. If no roads exist, you may
have to do some clearing to provide access for the vehicles and
personnel.
In hilly, rocky, or swampy terrain, this may cause
serious problems.
It may be necessary for you to choose a site of
lesser technical desirability in order to avoid wasted time
establishing accessibility.
Environmental hazards such as flooding, landslides, blizzards, etc.,
present potential problems, both logistically and tactically.
Whenever possible, locate your site near good roads to facilitate
resupply and movement.
2-5
SS0016
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