c. The SNAP-1 combines signals received from two separate antennas to
create a radio reception pattern containing a null. The SNAP-1 effectively
becomes the antenna control system and must interface and operate with the
radio. The SNAP-1 also:
(1) Automatically blocks an unwanted signal from the radio receiver.
It does this without interfering with the desired signal coming from a
different direction.
(2) Operates
on-the-move
or
stationary,
using
current
vehicular
mounted radios.
(3) Can automatically block signals, even when the operator does not
know the jammer's location or when the jammer is moving.
(4) Permits
normal
cipher
and
plain
text
voice
and
data
communications over associated COMSEC and radio.
(5) Allows passing of the desired signal.
This occurs even when the
friendly transmitter is not equipped with SNAP-1.
(6) Uses standard Army VHF-FM antennas.
PART C - SIGNAL SECURITY MEASURES
1.
Signal Security. A close relationship exists between ECCM and SIGSEC.
When an enemy does not have access to or knowledge of EEFI, his
effectiveness is reduced. SIGSEC's major function is to deny an enemy the
ability to exploit friendly electromagnetic spectrum use.
Its techniques
include emission security and control, transmission security, cryptographic
security, and physical security.
2.
Emission Security and Control. This involves preventing an enemy from
targeting friendly communications. If enemy EW units do not know a friendly
unit is present, they cannot target it. Denying an enemy the ability to
detect friendly units is possible when friendly radio operators-
a. Turn on emitters only to meet minimum requirements.
b. Use the minimum amount of power needed to pass information.
c. Mask antenna locations.
d. Use directional antennas.
SS0135
2-12
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