TM 11-5820-890-10-3
JAMMING AND ANTIJAMMING
SINCGARS is jam-resistant due to its frequency hopping capability. Also, hopsets have been designed to reduce the
effects of jamming. However, in the event that SINCGARS is jammed, it may be necessary for you to take corrective
actions. The action you take depends on the type of jamming or interference that is disrupting net communication as well
as the authorized FH hopset(s) that is available to your net. A table is provided for the operator in Chapter 2 that lists
symptoms, possibilities, and corrective actions to be taken.
NOTE
Keep it simple. If possible, make no changes to communication during engagement or hostile action. In
a hostile battlefield environment the enemy may employ electronic warfare Electronic Countermeasures
(ECM) techniques in an attempt to halt or disrupt your communications. You must be able to identify
jamming techniques and know how to counter them when necessary.
The simplist method the enemy can utilize to disrupt your communication is to transmit noise or audio signals on your
single channel operating frequency, or on multiple FH frequencies during FH operation. If the enemy can generate enough
power on your hopset, it is possible that your communication capability will be disrupted or even stopped. One of your
most difficult tasks is to identify jamming signals. Refer to the following procedures when a member reports jamming
problems or when you determine you are being jammed. Different jamming situations require different antijamming
procedures.
SITUATION: Your net has been operational and communications has been good with all stations. The next time stations
report, you suddenly receive a great deal of noise and are unable to hear several of net members. You receive noise even
though no real communication is occurring; a nearby member reports noise reception. You are probably being jammed.
Perform the following steps to confirm and counter jamming:
a.
Disconnect antenna. This determines if the noise is internal or external to your radio. If the noise continues,
your radio may be faulty.
b.
Check power supply, RT and antenna ground. A bad ground can conduct noise into the RT.
c.
Move or reposition the antenna. If communications improve, you probably are not being jammed.
d.
Notify your supervisor of suspected jamming signals.
e.
Increase RF power.
f.
CONTINUE TO OPERATE! Do not discuss the jamming problem over the air.
g.
Increase antenna height.
h.
Update the net. Changing the hopset may eliminate disruptions.
SITUATION: The enemy may employ what is referred to as subtle jamming. Subtle jamming is more difficult to detect
than noise generated signals. You will not hear any noise or incoming signals and even though everything seems to be
normal, communication is disrupted. Follow the same antijamming procedures listed above.
Again, CONTINUE TO OPERATE and DO NOT discuss suspected jamming over the air. Begin antijamming as SOP
dictates.
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