Quantcast FREQUENCY SELECTION.

 

Click here to make tpub.com your Home Page

Page Title: FREQUENCY SELECTION.
Back | Up | Next

Click here for thousands of PDF manuals

Google


Web
www.tpub.com

Home

   
Information Categories
.... Administration
Advancement
Aerographer
Automotive
Aviation
Construction
Diving
Draftsman
Engineering
Electronics
Food and Cooking
Logistics
Math
Medical
Music
Nuclear Fundamentals
Photography
Religion
   
   

 

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Back
Figure 2-2. Antennas for Use With the Radio Set
Up
TM-11-5820-919-12 Radio Set AN/PRC-104(A) (NSN
Next
Telegraph Communications


TM 11-5820-919-12
Quickly assemble and erected
2-30
SITE SELECTION.
requires two vertical supports
(trees, etc.)
2-31.  Site selection is particularly important for short-
range, ground wave communications.  The existing
Good gain extended range (0 to
tactical situation will determine how much of a selection
300 miles and beyond)
is available. Generally, the best communications will be
obtained  if  the  transmitting  site  is  clear  of  all
QUARTER WAVE
Basically bi-directional
obstructions, located in an area with good ground
SLANT WIRE
conductivity (wet or plowed ground) and as high above
Good portability
ground as possible.  Several locations in the same
general vicinity should be checked as possible sites. A
Quickly assembled and erected
slight change in antenna location can make a substantial
requires only one vertical support
difference in effectiveness.
Fair gain ; moderately extended
2-32.  Avoid  areas  near  sources  of  electrical
range (to 1000 miles)
interference such as power lines, radar sets, field
hospitals with X-ray machines, etc.  Also avoid large
2-26.
FREQUENCY SELECTION.
structures having metallic content bridges, tanks, steel
reinforced buildings, etc.
If enemy jamming is a
2-27.  The primary considerations when selecting an
possibility, the site should be selected so that a large
operating frequency  are the distance b)between the
object or terrain feature is situated between the radio and
sending and receiving stations, and the time of day'.
the jamming source. This minimizes the effects of the
Refer to Appendix II, figures A24 and A25 which relate
jamming station and makes it more difficult to locate your
the relative effective less of communications for four sub-
transmitter using direction finding equipment.
band segments to the tile of day.  These figures are
based on average propagation characteristics for the
2-33.
MODES OF OPERATION.
sub-ands and are intended for rise only as a general
guide.  For detailed frequency planning over a specific
2-34.  The radio set mode of operation is dependent
time period, propagation prediction charts are able from
upon tactical requirements. The following conditions are
several government agencies. ("Intermediate and Short
examples of the types of conditions which may be
Distance
Sky-Wave
e  Propagation
Charts",
encountered.
Headquarters U.S. Army Communications Electronics
Engineering Installation Agency, Ft. Huachuca, Arizona
2-35.  NORMAL COMMUNICATIONS.  For two-way.
8.5613)
communications under normal circumstances, the radio
set should i be operated on _R. This selection permits
2-28.  Another consideration selecting an operating
the radio to transmit and receive voice (or cw
frequency is the atmospheric condition. If rain or other
communications on any of the 280,000 frequency
precipitation is present, signals at the lower end of the hf
settings.
band may be degraded by atmospheric noise while the
higher frequencies will be affected to a lesser degree.
2-36.  RADIO  SILENCE.  When  field conditions
Therefore, higher frequencies  will  provide  more
require that no radio transmissions be made, the node
effective communications in inclement weather.
selected should be V-RCV or DRC,V.  These modes
render the radio set passive and inhibit the modulator in
2-29.  The most useful phenomenon in radio wave
order to prevent transmission. When V-RCV is selected,
propagation is the "skip" effect.  This effect occurs
the radio set receives voice (or cw) but cannot transmit.
l)because the layers of the ionosphere become ionized
When DRC:  is selected, the radio set receives data
l)y the ultraviolet radiation of the sun.  This level of
information but does not transmit data.
ionization determines the highest frequency for skip over
a given distance.  Generally, the higher the ionization
2-37.  Data Communication.  When field conditions
level, the higher the fre(quency that can be used in "skip"
require transmitting and receiving data, the radio set
mode and therefore the broader the range of frequencies
mode selectetd is D-TR. This Mode permits two-way
available
for
rise
2-7


Privacy Statement - Press Release - Copyright Information. - Contact Us

Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business