Section V. Communications Under Special Conditions
The environment can take a severe toll on communications. This section addresses a few specific problems involved in six environments: cold weather, desert, jungle, mountain, urban, and nuclear.NOTE: The operator must perform PMCS to maintain all equipment in an operational status.
5-6. Cold Weather Operations
Soldiers must be trained on cold weather safety. Extra precautions must be taken with heaters and open fires. Carbon monoxide poisoning is a constant danger. Snow and ice build-up on tents and vehicle canvas can cause tearing.
Generators and Vehicles. Grounding is difficult in frozen earth. Gloves must be worn when handling all metal objects. If possible, use existing underground pipes or above ground structures to get an adequate ground. Antifreeze and lightweight oil must be used for all vehicles during cold weather operations. Liquid cooled generators also need antifreeze. Maintenance personnel must check antifreeze levels often. Water may appear in fuel and fuel lines. Do not use contaminated fuel. The fuel must be drained from the vehicle and new fuel added before operating the vehicle. Keep dry batteries warm and charge wet-cell batteries. Vehicles must be started at least once a day and operated for 10 minutes at a high revolutions per minute (RPM) to charge the battery. Keep tire chains tight to avoid damage to vehicles.
Radios. Water vapor from the breath can freeze and make a microphone useless. Use de-icing shields to prevent this. Ice on antennas can cause damage and make it hard to extend or lower the antenna. Ice can be melted from the mast using a hose attached to the exhaust pipe of a vehicle. Direct the hot air on the ice until it melts.
Wire. Condensation and ice on connectors make connecting the cables difficult and can degrade the signal path. Care must be taken to keep connectors dry. Extreme care must be taken in handling cables at low temperatures. When the rubber jackets become hard, the cables must be protected from stretching and bending to prevent short circuits caused by breaks in the covering. If cables are to be bent, they must first be warmed.
5-7. Desert Operations
Two of the biggest problems involved in desert operations are dust and extreme heat. Dust and sand particles damage equipment. The heat can take its toll on generators, wire, communications equipment, and personnel.
Generators and Vehicles. Grounding equipment is difficult and can be accomplished by burying grounding plates in the sand and frequently pouring salt solutions on them. Special attention must be taken to ensure air filters are cleaned daily to prevent equipment damage.
Radios. Keep all radios cool and clean. Keep them in a shaded or ventilated area whenever possible. Cover hot radios with a damp towel without blocking the air vents. Evaporation will cool the radio. After dark, rapid temperature drops can cause heat inversion that can disrupt radio communications until the atmosphere stabilizes. Desert terrain can cause excessive signal attenuation making planning ranges shorter.
Wire. Bury wire and cables deep in soft sand, if possible. This prevents damage to the cable insulation.
See FM 90-3 for more information on desert operations.
5-8. Jungle Operations
During jungle operations, movement and visibility are reduced by terrain and heavy foliage. This same terrain and foliage provides adequate cover and concealment. Humidity and heat can cause condensation. Microphones, wires, cables, and gauges are especially susceptible to moisture and fungus. Battery life is shortened. If air conditioning is available, it is very effective against high humidity.
Radios. The range of radio communications is reduced. VHF and UHF radios are limited by jungle growth and terrain that absorb transmissions. HF radios are more effective. Airborne radio retransmissions are used to overcome dense vegetation.
Wire. Dense vegetation and difficult terrain limit using wire in jungle operations. Aerial wire installation can be used as an alternate dispensing method due to mobility restrictions in jungle terrain.
See FM 90-5 for more information on jungle operations.
5-9. Mountain Operations
Mobility is difficult in mountainous terrain, and it can be difficult to find a level area for a communications site.
Generators and Vehicles. Generators and communications assemblages need level ground to operate properly. It is difficult to drive ground rods and guy wire stakes into rocky, mountainous terrain. The rocky soil provides poor grounds, however, adding salt solutions will improve the electrical flow.
Radios. When operating in mountainous terrain, additional retransmission assets will be needed. LOS paths are much more difficult to gain. Use of relays improves communications. Positioning antennas is crucial in mountainous terrain because moving an antenna even a small distance can drastically affect reception.
See FM 90-6 for more information on mountain operations.
5-10. Urban Operations
Seizure of cities and towns consume enormous resources, degrade the momentum of offensive operations, restrict maneuver, and are time-consuming.
Radios. Large buildings and electrical interference greatly hamper LOS communications. Using retransmission helps to alleviate the problem. Aerial retransmission is the most effective. If this is not available, install antennas as high as possible. Avoid using church steeples and other obvious places. It is better to select a common type of building and install the antenna. Consider the background before camouflaging antennas. Remember to remote radios to separate the operators from the equipment. Position retransmission stations near intersections to provide better coverage.
Multichannel Radio. The effectiveness of multichannel radio is reduced in an urban area because the radios require LOS. LOS between units is nearly impossible in built-up areas. Install multichannel radio systems only after the city is relatively secure. Use an SHF radio shot to bring the circuits into the supported headquarters.
Telephone and Wire. The prompt seizure of the city and existing communications facilities are very important. Notify parent headquarters of controlled telephone numbers. Public or private telephones coupled with stationing messengers at the phones can provide excellent emergency communications. Initially, telephone and wire lines have limited use. Installation in sewer systems, subway tunnels, or through intact buildings provides increased protection for the wire. Use aerial or overhead construction when installing wire along city streets.
Visual Signals. Pyrotechnics, smoke, and marking panels are means of communications in the city.
5-11. Nuclear Environment
A nuclear environment is very damaging to sensitive signal equipment. Leaders must know how to protect vital assets for future use.
Electromagnetic Pulse (EMP). The radiation from a nuclear burst produces EMP. Gamma rays radiate outward from the burst and strip electrons from the atoms in the air. This creates a virtual wall of fast-moving electrons as the radiation sweeps outward in an expanding wave. This process creates a region of high voltage and strong interference.
Susceptibility. Signal equipment is very susceptible to EMP. Normally, the smaller the individual component, the more susceptible it is to electronic attack (EA).
EMP Protective Measures. All equipment not required in primary systems should remain disconnected and stored within a sealed shelter or other shielded enclosure for protection from the EA. This measure reduces the likelihood of all equipment being simultaneously damaged by EMP and provides for backup components to reinstall affected systems.
Wire and Cable. Wire and cable should be shielded and properly grounded. The cable length must be kept as short as possible. Shields on all cables connect to the grounding systems where provided.
Radios. Antennas should be disconnected from radio sets when not in use. Reduce operational nets to a minimum. Most tactical radios with fully closed metal cases will provide adequate EMP protection if all external connectors have been removed. Placing items in vehicles, vans, and underground shelters provide effective protection.
Continue with Chapter 5
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