The reconnaissance platoon's primary mission is to provide information to the commander about the battlefield environment. The platoon's primary means of communication is the FM radio. This appendix focuses on communication techniques and procedures. It also discusses imitative communication deception and authentication, visual signals, and use of local telephones.
Without effective communications, the reconnaissance platoon is worthless to the battalion. Setting up and maintaining communications is routine but sometimes challenging. The reconnaissance platoon uses all available means of communication; however, the FM radio is the platoon's primary source of communication. Ensuring that the platoon is able to communicate is a primary concern of the battalion commander and his staff The signal officer ensures that the battalion's communication plan includes provisions that will allow the reconnaissance platoon to communicate effectively. The platoon leader coordinates with the signal officer to ensure that he understands the communications plan. The reconnaissance platoon operates on the battalion operations and intelligence net, the command net, or both, depending on the SOP. Internal communication is accomplished on the platoon net. (Figure E-1.) shows a radio diagram for the platoon.)
Figure E-1. Radio diagram.
a. Battalion Communication. To ensure effective communications,
the signal officer can--
- Set up retransmission stations. If not available, the platoon sergeant can set up an internal relay station.
- Send communications teams with squads (for example, high frequency radio).
- Provide special equipment such as TACSAT.
- Organize a relay through a forward deployed force.
- Use a combination of the above.
b. Special Equipment. When the reconnaissance platoon is given a mission that requires special communications equipment, the battalion signal officer requests the equipment through the brigade signal officer. If the brigade does not have the assets to satisfy the request, the request is sent to the division. Based on the availability of assets, the division will task the proper agency to fill the request. The reconnaissance platoon should be trained to use the specialized communications equipment. TACSAT is one type of specialized communications equipment that does not always come with operators. However the TACSAT will usually have trained operators. (AN/PSC-3) ( Figure E-2) is a rugged, lightweight (35 pounds) portable device used in quick-reaction situations where extended communication range is essential to mission effectiveness. The AN/PSC-3 can operate on the move with its whip antenna or in the at-halt/satellite mode. It transmits or receives in voice or data formats in both modes. The equipment can be used with speech security equipment.
Figure E-2. Special communications.
c. Site Considerations. A radio station should be in a position
that allows the best communications while maintaining physical and
communications security. Hills and mountains between stations limit the
range of radio sets. When possible, a location is selected that allows
LOS communications. Locations that provide the enemy a jamming capability,
visual sighting, or easy interception are avoided. Table E-1 shows the
LOS range planning for radios and antennas.
(1) Do not select an antenna position in a tunnel or beneath an
underpass or steel bridge. Transmission and reception under these
conditions are impossible due to high absorption of radio-finding energy.
(2) Use buildings to camouflage the antenna from the enemy. However, buildings between radio stations, especially steel and reinforced concrete structures, hinder transmission and reception.
(3) Avoid all types of pole wire lines. Wire lines absorb power from radiating antennas in their vicinity. They also introduce hum and noise interference in receiving antennas.
Table E-1. LOS range planning.
Table E-1. LOS range planning (continued).
When the platoon's radio antenna is damaged or destroyed during a mission, it must be repaired, or a field-expedient antenna must be built. In some situations, these antennas can extend the radio's normal range and should be used whenever the situation permits. (See FM 11-64 for more information.)
a. Operation With a Broken Whip Antenna. An expedient splint is
a rapid means of repairing a broken whip antenna. ( Figure E-3.) The
paint is scraped off 3 to 6 inches from each broken end. The cleared ends
are overlaid and tightly wrapped together with about 1 foot of stripped
copper wire (which can be taken from inside WD-1 wire). A stick, pole,
or sturdy branch is then placed on each side of the break. The splint is
tightly wrapped with WD-1, rope, tape, or any available item.
Figure E-3. Metallic whip antenna (spliced).
b. Replacement of Broken Whip Antenna With Wire. If the whip
antenna is broken at the base, WD-1 can be used as an expedient replacement
( Figure E-4). The paint is scraped off the top 2 inches of the whip's stub.
Then 12 inches of insulation are stripped from one end of a 10-foot section
of WD-1. The stripped wire is tightly wrapped around the stub. It is passed
over the top of the stub and joined into the hole with a wooden peg. The
wire is secured to the stick with the peg and tape. Next, a 10-foot pole is
tightly attached to the antenna's base and stub. The remaining 9 feet of
WD-1 is attached along the pore with tape; the excess is trimmed away. The
total length of this expedient antenna should not be more than 9 feet.
Figure E-4. Wire replacement for broken whip antenna.
c. Directional Antenna. Direction and distance are critical factors
in determining good communications. An antenna is one of three types based
on its directional features ( Figure E-5).
- Omnidirectional--all directions.
- Bidirectional--any two opposite directions.
- Unidirectional--any one direction.
Each antenna has advantages and disadvantages. The omnidirectional or whip antenna enables communications without regard to the receiving station's location, but it is vulnerable to enemy radio direction-finding. The bidirectional antenna allows communications with two or more stations in opposite directions, but these antennas must be parallel. The antenna should be positioned at 90 degrees to the enemy lines to reduce the possibility of interception. A terminated long-wire antenna is unidirectional and the least open to enemy interception if properly positioned. Its disadvantage is that it transmits and receives best in only one direction.
Figure E-5. Directional antennae.
d. Antenna Length. To construct expedient, efficient antennas, the
wavelength of the frequency being used must be known. The length of the
antenna needed can be determined by using the proper formula below:
- To figure a quarter-wavelength antenna in feet, divide 234 (constant) by the operating frequency MHz.
Example: 234 divided by 44.8 = 5.22 or 5 feet 2 inches
- To figure a half-wavelength antenna in feet, divide 468 (constant) by the operating frequency in MHz.
Example: 468 divided by 56 = 8.36 or 8 feet 5 inches
- To figure a full-wavelength antenna in feet, divide 936 (constant) by the operating frequency in MHz.
Example: 936 divided by 45 = 20.8 or 20 feet 10 inches
A quarter-wavelength antenna is the minimum-size antenna. The half-wavelength or greater provides greater reliability. Five full wavelengths provide the optimum antenna length for any given frequency. (See Table E-2.)
Table E-2. Quick reference chart.
e. Vertical Antenna. Vertical antennas are omnidirectional. Most
tactical antennas are vertical--for example, the man-pack portable radio
and the radios in tactical vehicles. A vertical antenna can be made by
using a metal pipe or rod of the right length, held erect by guidelines.
The lower end of the antenna should be insulated from the ground by placing
it on a large block of wood or other insulating material. A vertical
antenna can also be a wire supported by a tree or a wooden pole (
Figure E-6 and Figure E-7). For short vertical antennas, the pole may be used
without guidelines (if properly supported at the base).
(1) Use a quarter-wave antenna to replace a regular whip antenna
The following steps explain how to erect a quarter-wave vertical antenna:
STEP 1. Use the quick-reference chart in Table E-2 or the
formula for a quarter-wave antenna to determine the
length of the wire (WD-1) needed.
STEP 2. Attach an insulator to one end of the wire and insert the other end (stripped) into the antenna connector on the radio.
STEP 3. Tie a rope to the insulator end and throw the rope over a limb.
STEP 4. Pull the rope until the wire is vertical.
Figure E-6. Field substitutes for support of vertical wire antenna.
Figure E-7. Extra support for vertical wire antenna.
(2) If using insulated wire, be sure to loop the wire around the handle
of the radio before attaching it to the antenna connector. If the antenna
is made of bare wire, use a stake and insulator to prevent the antenna wire
from pulling out of the antenna connector on the radio.
f. Field-Expedient Unidirectional Antenna. The reconnaissance platoon can improve its ability to communicate by using field-expedient antennas. While moving, the platoon is usually restricted to short antennas; however, when stationary, expedient antennas allow farther broadcasting farther and clearer reception.
(1) Vertical half rhombic. The vertical half-rhombic antenna
( Figure E-8) is a field-expedient unidirectional antenna.
Figure E-8. Vertical half-rhombic antenna.
THIS ANTENNA SHOULD NOT BE USED ON AN RT-524 IN HIGH POWER. SERIOUS DAMAGE TO THE RADIO CAN RESULT.
STEP 1. Determine the direction of the station to be
reached and line up the antenna. Plan all work
in that direction.
STEP 2. Build the antenna.
(a) Cut 100 feet of wire for the antenna.
(b) Cut 91 feet of wire for a counterpoise. (This is a wire stretched across the bottom of the antenna. It is an artificial ground that helps to produce the required radiation pattern.)
(c) Connect an insulator to each of the antenna wires and one at the middle. Add a tie-down wire outside the insulators on each of the antenna wires.
(d) Connect the counterpoise to the insulators at the same point as the tie-down wire.
(e) Select or erect a middle support (a tree, pole, or a wire or rope suspended between two trees or structures). The midpoint must be at least 30 feet high.
(f) Stretch the counterpoise out in the direction of the target station with the middle of the counterpoise at the center support. Drive the stakes in by each tie-down wire, stretch the counterpoise tightly, and tie it down to the stake. Elevate the center of the antenna until it is right.
(g) Run the wire from the antenna terminal and connect it to the antenna above the insulator. Run a second wire from the head of the screw on the radio case to the bottom of the insulator.
(h) Place a 600-ohm, 2-watt carbon resistor at the end toward the desired station to make this antenna transmit only toward the desired station. Ensure the resistor is carbon and not wire-wound. A 2-watt resistor works for the AN/PRC-77, but a resistor with wattage rating of half the power output is needed for the higher-power ratio.
(2) Long-wire antenna. The field-expedient long-wire antenna ( Figure E-9) is a directional antenna that can be easily made out of readily available materials. A 500- to 700-ohm resistor, which can be acquired from the communications sergeant or made as in Figure E-12, should be used at the far end of the antenna. To build this antenna, the antenna wire (WD-1) is cut to between 2 and 5 full wavelengths of the operating frequency. It is attached to the long whip base of the radio set and then run through the insulator as shown in Figure E-12 (1). The wire is then run through the second insulator (2), down to the resistor (3), and ends at the ground stake (4). Another wire is attached to the opposite end of the resistor and run back to the radio set where it is attached to the radio set case (ground). The direction of transmission is toward the end of the antenna with the resistor. The radio is turned on, and communications are checked.
Figure E-9. Long-wire antenna.
(3) OE-254 improvised antenna. This antenna can be used in wooded
areas where a tree limb can be used to raise it. The following steps can
be used to build this antenna.
STEP 1. Use the following formula by cutting four wires of
Length of wire (meters) = 142.5/frequency in MHz
EXAMPLE: 2-meter lengths = 145.5/71.2 MHz
STEP 2. Connect three wires to one end of an insulator (Figure E-10). Form an equilateral triangle with sticks, and attach the free end of each of the three wires to a corner of the triangle.
STEP 3. Connect one end of the fourth wire to the opposite end of the desired insulator in STEP 2. Connect the free end of the fourth wire to another insulator. Tie a rope or wire to the insulator, which will be used to throw over a tree branch and to pull the antenna into the air.
STEP 4. Before raising the antenna, connect WD-1 to the lower insulator (described in STEP 2) as shown in Figure E-10. At the radio, connect any wire of the WD-1 to the radio chassis and one wire to the radio connector.
Figure E-10. OE-254 improvised antenna.
(4) V-antenna. The V-antenna (Figure E-11) is a field-expedient
unidirectional or bidirectional antenna. It has two wires forming a V
pointing toward the desired direction of transmission or reception. To
make construction easier, the legs may slope downward from the apex of
the V. This is called the sloping V-antenna (Figure E-12). The angle
between the legs varies with the length of the legs to achieve the greatest
performance. Table E-3 is used to determine the angle and the length of
the legs. When the antenna is used with more than one frequency of
wavelength, an apex angle is used midway between the extreme angles
determined by the chart. To make the antenna radiate in only one
direction, add noninductive terminating resistors from the end of each leg
(not at the apex) to the ground. The resistors should be about 500 ohms
and have a power rating of at lease one-half that of the output power of
the transmitter being used. Without the resistors, the antenna radiates
bidirectionally, both front and back. The antenna must be fed by a
balanced transmission line.
Figure E-11. V-antenna.
Figure E-12. Sloping V-antenna.
(5) Field-expedient resistors. Resistors are used in the construction
of some antennas to make them unidirectional. Sometimes, a manufactured
resistor can be hard to obtain. A field-expedient resistor can be made
using the following methods:
(a) One method is to use an old, cylindrical-type earplug case to
make a simple and adequate resistor. Cut the chain on the earplug case
close to the center. Open and fill the case with water from a canteen; pour
one to two salt packets from the MRE pouch into the water and reseal
the container. Attach one end of the antenna wire to one side of the
earplug case (Figure E-13). Attach the other side of the antenna wire to
the opposite side of the earplug case. Then, complete the circuit as in the
instructions for the specific antenna.
Figure E-13. Expedient resistors.
(b) Another method is to use the carbon core of the BA-30 battery.
Cut open the battery and remove the core, using only the carbon core.
Attach this resistor to the antenna the same way as the earplug resistor.
Both resistors provide about 500- to 1,000-ohm resistance, which is
enough for most low-power military radio sets.
(6) Antenna insulators. If a field-expedient antenna's transmitting element is not properly insulated, it may become shorted to the ground and be ineffective. Many items can be used as field-expedient insulators. The best items are plastic or glass, which include plastic spoons, plastic buttons, plastic bags, and glass bottle necks. Wood and rope or both are less effective than plastic or glass. The radiating element--the antenna wire--should touch only the antenna terminal; it should be physically separated from all objects except the supporting insulator.
Jamming is an effective way to disrupt control of the battle. All that is required is a transmitter, tuned to a friendly frequency, with enough power output to override the signal at the receiver. Jammers operate against receivers, not transmitters. They are especially effective against voice, data, and communications circuits using on-line encryption devices. Many sophisticated jamming signals can be used. Any jamming must be reported accurately, using the MIJI report format. (Refer to FM 34-1.) The two types of jamming are as follows:
- Obvious Jamming. The enemy can use obvious interference jamming such as steeped tone (bagpipes), random-key Morse code, pulses, and recorded sounds.
- Subtle Jamming. With subtle jamming, the operator may not realize he is being jammed because no sound is heard from the receiver.
a. Jamming Countermeasures. When RATELOs experience radio
interference, they must try to determine its source. The following
steps can help in determining the type of interference:
(1) Check the frequencies on either side of the Operating frequency.
The enemy normally works against selected targets (spotjam) to protect
his own communications. If the signal strength falls off on either side
of the operating frequency, the radio is probably being spotjammed.
(2) Detach the antenna. If the interference continues, it means internal equipment troubles. If it stops, it is outside interference.
(3) Move to a new location. If the signal strength varies greatly, the radio may have been too close to power lines or generators. If it does not vary, the radio is probably being jammed.
b. Interference Techniques. Once the interference has been identified as jamming, the following steps should be taken:
(1) Report the jamming using a secure means. To prevent the enemy
from knowing the results of his jamming efforts, do not announce over
nonsecure radio or wire circuits that the station is being jammed.
(2) Try to work through the jamming by increasing transmitter power. Move the antenna to a position where it is masked from the enemy jammer, and slow down the rate of transmission. When using voice radio, repeat each word and make the greatest use of the phonetic alphabet. Do not yell into the microphone as this only creates garbled reception, not stronger signals.
(3) Make and use a horizontally polarized directional antenna to increase the effective radiated power of the radio. ( See paragraph E-2.)
(4) Switch communications modes if all attempts have failed to evade or work through jamming. Data, teletypewriter, and other pulse train communications systems are most susceptible to jamming. Secure voice and low-level OPCODEs are less vulnerable, and Morse code CW is the least affected. Wire systems and messenger service are reliable as an alternate means.
(5) If tests show the probability of jamming, follow local SOP to restore communications and to start a MIJI report, informing higher headquarters of the jamming.
E-4. IMITATIVE COMMUNICATIONS DECEPTION AND AUTHENTICATION
Besides RDF and jamming, the enemy's EW arsenal contains another weapon called deception. Once the enemy has a clear picture of the communications networks, he could try to enter selected nets disguised as a friendly station. This action is called imitative communications deception. The enemy uses language experts who speak with the latest slang and accents, and who are thoroughly drilled in proper communications procedures. The enemy ICD experts are believable. If accepted into friendly nets, they reward trust with deceit. ICD could result in the shelling of friendly forces, walking into enemy ambushes, or deploying to the wrong positions.
a. ICD is probably the easiest EW technique to counter. The enemy
must have a complete, in-depth knowledge of the opposing communications
systems and operating procedures. He must be able to blend into friendly
networks to be accepted. Therefore, any procedure implemented to block
this ECM effort reduces his chance for success. Authentication is the
best way to stop ICD. In most cases, the called RATELO makes the first
challenge and is required to authenticate when--
(1) Suspecting imitative deception on any circuit; for example, when
contacting a station following one or more unsuccessful tries.
(2) Authenticating is requested or a station is challenged. This is not to be interpreted as requiring stations to break an imposed silence for the sole purpose of authenticating.
(3) Directing radio silence or listening silence, or requiring a station to break an imposed silence.
(4) Transmitting contact and amplifying reports in plain language.
(5) Transmitting operating instructions that affect the military situation; for example, closing down a station or watch, changing frequency other than normal scheduled changes, directing the setup of a special communications guard, requesting artillery fire support, or directing relocation of forces.
(6) Transmitting a plain language cancellation.
(7) Making the first radio contact or resuming contact after prolonged interruptions.
(8) Transmitting to a station that is under radio-listening silence.
(9) Transmitting an authorized classified message in the clear.
(10) Being forced, due to no response by a called station, to send a message in the blind (transmission authentication).
b. Authentication is not required when making first contact after a scheduled call sign and frequency change. Only friendly stations know their assigned call sign and frequency for the time in use. If the RATELO is not sure that authentication is required, he must challenge. If a station takes more than 15 to 20 seconds to authenticate, the RATELO must challenge again. A 15- to 20-second wait is necessary because an enemy operator will try to contact some other station and have it respond to that same challenge. Once the enemy receives an answer, he calls back and blames the delay on equipment failure.
E-5. SECURE OPERATIONS
The reconnaissance platoon's mission is to provide the commander information. This may require extended operations beyond the FEBA. To preclude problems with communications security, the platoon must be familiar with cryptographic equipment, codes, and ciphers.
a. The preferred method for maintaining secure communications is to
use on-line cryptographic equipment such as Vinson-speech secure equipment.
The platoon must be familiar with Vinson operations including over-the-air
rekeying (OTAR) procedures. The platoon can expect to zero Vinson keys as
a precaution to prevent compromise and must be able to receive new key from
the battalion over the radio.
b. All soldiers must be familiar with encoding and decoding procedures. Radio nets may be forced to operate in a nonsecure mode due to equipment failure or loss of key. Operation codes and numerical ciphers are necessary to allow the platoon to continue to transmit secure information until the radio net can be secured.
Arm-and-hand signals and pyrotechnics are other methods used to communicate. Arm-and-hand signals are common throughout the Army. They are used primarily to control small elements. Pyrotechnics are used to indicate messages and when arm-and-hand signals are inappropriate.
a. Arm-and-Hand Signals. Leaders use arm-and-hand signals to control
movement and initiate specific action by the viewer. All members of the
platoon should be familiar with both mounted and dismounted arm-and-hand
signals. (See FM 21-60 for more information.)
b. Pyrotechnics. Pyrotechnics produce either smoke or light and are consumed in the process. When used for communications, prearranged or prescribed signals are developed and used throughout the force. These signals are developed based on the color and characteristics of the pyrotechnic device used. Pyrotechnic signals supplement or replace normal means of communication and allow a large number of soldiers and or forces to be signaled quickly. They can be used for friendly identification, maneuver element control, fire support control, target marking, and location reports. When pyrotechnics are used, the signal and its meaning are included in the command and signal portion of the operation order and in the SOI.
(1) The following types of hand-held signal rockets are available:
(a) Star clusters. Star clusters are used for signaling and
illuminating. They are issued in an expendable launcher that consists
of a launching tube and a firing cap. These signals produce a cluster
of five free-falling pyrotechnic stars. Star clusters are available in
green, red, and white.
(b) Star parachutes. Star parachutes are used for signaling and illuminating. They are issued in an expendable launcher that consists of a launching tube and a firing cap. These signals produce a single parachute-suspended illuminant star. Star parachutes are available in green, red, and white.
(c) Smoke parachutes. Smoke parachutes are used for signaling only. They are issued in an expendable launcher that consists of a launching tube and a firing cap. The device is a perforated canister that is parachute-suspended. They are available in green, yellow, and red smoke.
(2) Smoke grenades are available in white, green, yellow, red, and violet smoke. These colors are provided by two types of grenades:
(a) White-smoke hand grenade. The white-smoke hand grenade is a
burning-type grenade used for signaling and for laying smoke screens.
When ignited, it produces dense white smoke for 105 to 150 seconds. It
will not normally injure exposed troops. In heavy concentrations, troops
should wear the field protective mask. However, the mask will not protect
against heavy concentrations of this smoke in enclosed spaces due to
oxygen depletion and carbon monoxide buildup.
(b) M18 colored-smoke grenade. The M18 colored-smoke grenade is similar in appearance to the white-smoke hand grenade, but its top is painted the color of the smoke it produces. Its filler is a burning-type mixture containing a dye; only four are standard: red, green, violet, and yellow. As a burning-type grenade, it has an igniting-type fuse and burns 50 to 90 seconds.
E-7. LOCAL TELEPHONES
The platoon often finds that radio communications are not a feasible means of relaying information, especially if the platoon is too far away to use FM radio, the mission requires radio-listening silence, or the platoon's equipment is inoperable. An option, other than messenger, is the use of the local telephone. In some areas of operation, telephone drop lines are incorporated as part of an overall plan. In other situations, soldiers should be briefed on and know a few simple requirements for possible use of local telephones. It is not a secure method and should not be relied on as a primary means of communication. Soldiers should adhere to the following guidelines regarding use of local telephones:
- Have local currency available.
- Know (as part of the plan) the telephone number of higher head-quarters.
- Know the proper use of the local telephone system.
- Learn enough of the local language to talk to the operator (if required). Know the emergency numbers of local police or ambulance.
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