Urban Communications

Excerpt Summary From the MAWTS-1 ACE MOUT Manual

When planning for urban operations, as with other missions, minimum-communications (min-comm) to no-communications (no-comm) evolutions must be considered from the start. There are many reasons why radios might not work in an urban setting and this problem must be anticipated. This is especially important when contingencies start to arise. No-comm contingency signals must be planned for and practiced in order to be effective. Without refined and executable back-up signals confusion becomes unmanageable quickly. Air to air communications should not be a problem at medium to high altitudes except in high threat Electronic Warfare (EW) situations. Communications between the Forward Air Controllers (FAC's), the Ground Combat Element (GCE) and Close Air Support (CAS) aircraft are likely to be degraded at low altitudes (below 500 feet AGL) due to intervening high rise structures that may restrict line-of-sight radio transmissions. Knowledge of friendly positions, target information, clearance to deliver and coordination all depend on adequate communications. Helicopters could possibly land near the objective area and conduct face-to-face briefs, although this may compromise the mission. An alternative to electronic communications in emissions control (EMCON) or EW environments is visual signalling. Visual signaling (mirrors, lights, color panels, flash cards, wing or rotor rocks - for example) are a positive step in preserving communications. The 160th SOAR used IR strobes to mark occupied buildings and as makeshift TRP's in Mogadishu. Satellite Communications (SATCOM) is another asset would alleviate many communications problems. Another alternative would be the use of a retransmission or radio relay site. A radio relay could be a Marine on top of a building or an airborne asset.

Operations in urban areas have demonstrated how easily VHF radios are screened and their ranges reduced. As a consequence, radios must be carefully located to maximize their effectiveness. Retransmission (retrans) stations and remoting of antennas to high ground are methods to maximize VHF radios and even PRC-113 radios used by FAC's. Ground units attempting to communicate with aircraft or other ground units should use the upper end of the VHF band and high power switches on radios. Commanders must set limited objectives, covering a small area, and plan for the frequent relocating of retrans stations. If time and the battle situation allow, maximum use should be made of the civilian telephone system (if operational).

During Operation Just Cause, the two most significant elements of the Army communications network were the Airborne Command and Control Center (ABCCC) and the state of the art SATCOM radios utilized by the ground and air elements alike. In addition, multi-channel unit radios provided essential command and control links. Commercial walkie-talkie's (Bricks) were used by several units to augment their administrative communications. Brick radios were used for perimeter security and communications within logistical areas.

Large cities have power lines, electric trains, trolley lines, and industrial power lines which can interfere with communications. However, there are instances where such transmission lines retransmit an intensified signal along the same path as the transmission lines. Conversely, these lines can generate from 100-300 times the interference over normal atmospheric interference on the UHF band.

A directional antenna can use stone or brick walls as passive retransmitters to bound signals down a street. Radio retransmitters should be positioned at crossroads in order to communicate with elements on perpendicular and other streets. If the city has tall buildings with iron support beams or if the buildings have metal roofs, position UHF transmitters some 2-5 times the height of the intervening building away from that building. When trying to bounce radio signals off adjacent buildings, avoid aiming for windows. The reflective properties of glass are different than brick or stone. Further, most window glass near fighting will be shattered and bounced signals can be trapped in rooms.

Avoid positioning radios near power and telephone lines. If a radio is located inside a building, its antenna must be positioned at an upper-story door or window facing the receiving station or on the roof. A directional antenna is better than a whip antenna. The best places to situate a radio are in the basement or under the stairs. Use a 10-15 meter long cable to connect the radio to the antenna, but avoid longer cables as they weaken the transmission. Whereas a whip antenna attracts enemy attention and fire, practically every building has a television antenna. It is best to dedicate one radio set to communicating with a separate subunit, rather then trying to communicate over a net. However, a whip antenna must be used with a multiple-subscriber net. Sometimes, this may involve positioning the radio set itself on the roof close to a television or radio antenna mast. In that case, run a radio-telephone remote unit from the radio to the sheltered area. Often moving the antenna a few meters can improve reception. Communications using a directional antenna with a clear line-of-sight to the other station is best. When a tall object such as a church is located between the stations, the stations should aim their directional antennas at a common point.

When possible, use the civilian telephone network. Apartment buildings, stores, and factories are wired into the civilian telephone system. Every building has a telephone distribution box which controls 50- 200 individual telephone lines. It is relatively easy to set up wire communications using these points.

Cellular telephones work well in cities - - for either side. Cellular phones can be knocked out by taking out the repeater stations throughout the city or destroying the central cellular telephone system. Both practically require capturing the city first. Another way to attack cellular phones is to use the signal from the repeater station's omnidirectional antenna to locate and then target with indirect fire. Yet another way, is to knock out the microwave or satellite link to limit communications to the local area. Unless the ground terminal for the satellite or microwave can be destroyed, the other option remains grim - attacking the international commercial systems - this is highly undesirable and requires clearance form the highest levels. The Chechen resistance leader Dudayev was reportedly killed on the night of 21 April 1996 by a Russian aviation strike while using a cellular phone. This suggests the possibility that the Russians were monitoring cellular phone calls to track and target Dudayev.

Marine forces must also appreciate the growing importance of computers, fiber optics and amateur radios on the battlefield. These have the potential to be prime sources of enemy communications. Computers hooked to the Internet can relay a commanders orders to his subordinates and - depending on the sophistication of the system - can include audio, video, graphics and images.

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