I. Signaling

Preface
Transmission security (TRANSEC) measures are those steps taken to protect transmissions from unauthorized interception, traffic analysis, direction finding, imitative deception, jamming, or other exploitation. Any soldier who becomes a communicator, be it by way of radiotelephone or land line telephone, becomes responsible for taking the necessary measures to minimize the amount of information obtainable by the enemy.

International/NATO Phonetic Alphabet, Numbers, & Morse Code
The phonetic alphabet was developed to cut down on confusion during conversations. Spelling also became confusing with "b", "d", and "e", therefore this alphabet was developed to ease problems in communications.

The NATO Phonetic Alphabet was developed in the 1950s to be intelligible (and pronounceable) to all NATO allies in the heat of battle. It replaced other phonetic alphabets, for example the US military "able baker" alphabet. This is the one we used in WWI: Able, Baker, Charlie, Dog, Easy, Fox, George, Hypo, Inter, Jig, etc. There were other problems during WWII; the Army used the word "Able" for "A" while the Navy used "Affirm." By 1961, we again have one alphabet used by all services, maritime units, aircraft, and amateur radio operators.

The NATO Phonetic Alphabet is now widely used in business and telecommunications in Europe and North America. There are dozens of other standards in use throughout the world, but then the great thing about standards is that there are so many to choose from.

Morse's original code was not quite the same as the one in use today. In particular C, O, R, Y and Z contained spaces within the letter codes which must have been tricky to handle, and the numbers were different. This ‘American’ morse code was in wide use until the 1920’s. For international use it was modified as a result of a conference in Berlin in 1851; this regularized the code on a more rational basis and eliminated the spaces within the letters, but equally important from a European point of view it provided codes for accented letters.

Both the original code and the current International Code use the same principle, that the commonest letters have the shortest codes. How to find out what the letter incidence is? Difficult now, from scratch, but Morse had a marvellous idea. He went to his local newspaper. There he found compositors making up pages by hand from individual letters; capital letters were in one case or tray of type, and this was set above the case of small letters. This is the origin of 'upper and lower case' letters. Morse simply counted the number of pieces of type for each letter, thinking, soundly enough, that this must be related to the number needed. Thus 'e' has the shortest code, 'dit', whereas 'z' is (now) 'da-da-di-dit' and 'q' (now) 'da-da-di-dah'. Notice that I write them as they sound; morse was a visual code in the early days, but it is now an aural one.

The apparently well-known SOS distress call is not quite what it seems. Fancifully represented as 'Save Our Souls', it actually means no such thing. It isn't even SOS; it is a procedural signal, and the three dots - three dashes - three dots are sent as a single signal without the gaps that would be present if three separate letters were being sent. The distress call is

di-di-di-dah-dah-dah-di-di-dit
and not
di-di-dit  dah-dah-dah  di-di-dit

POW Tap Code
The Prisoner of War (POW) Tap Code is executed using the following chart. The tape code can be used orally, visually, or by mouth. Sweeping with a broom, chopping wood, whistling, playing a musical instrument, etc. Tap down the A-F-L-Q-V column to the row with the desired letter. Tap across the row to the desired letter. Use the letter "C" in place of "K".

An aid to easily remembering the tap code is to memorize the F-L-Q-V column. When receiving the letter "D" for example, you should hear "A" with the first set of taps, and hear across the "A" row, A-B-C-D, you have the letter "D".

Examples:

• "D" = A (pause) A-B-C-D

• "H" = A-F (pause) F-G-H

• "Q" = A-F-L-Q (pause) Q

When using the tap code, numbers are sent by a slow tapping until the number desired is reached with a long pause between digits. Zero is sent as the letter "O". For example: 36 = ... ......

Sign Language
The sign language alphabet is utilized by the hearing impaired and can also be used by EPWs. It is much faster than the Tap Code, but it is not as visually covert although it is more audibly covert. The palm is facing at a 45 degree angle across the body. Pause slightly between words. The arm does not move when finger-spelling. Each hand-shape is clearly formed. There are variations of the sign alphabet and there are often additional hand-shapes for double letters. For simplicity, if you have a double letter just sign the same letter twice.

Send numbers by waiving fingers slowly. Begin with your palm facing outward. For numbers 6-9, sign the number 5 and then 1-4. For numbers with multiple digits, sign the first digit with your palm facing outward and the second digit your palm facing inward. Then continue alternating the direction of your palm to switch digits.

II. Field Expedient Antennas

Introduction
When choosing a location for a field expedient antenna, please keep in mind the affects of elevation, terrain, vegetation, moist ground, salt water, power lines, overpasses/tunnels, bridges, buildings, and radio-wave broadcasting devices, and other things that may cause interference.

There are so many different field expedient antennas for several reasons. The environment might dictate whether there are trees at your disposal. The materials might dictate which antenna you can build. The range is also a deciding factor since you want to pick the antenna with the smallest range to accomplish the mission. Too large of a range and you might be broadcasting to the enemy. Some antennas are uni-directional, such as the Slant Wire Antenna, which is important also in regards to nearby enemies. Keep all these factors in mind when choosing which type of antenna to build and where to place it.

Suspended Vertical Wire
Range: 1 -1½ x normal range

Materials Needed:

• 1 radio (AN/PRC-77, AN/PRC-119A with adapter)

• Wire (WD-1)

• 1 insulator (MRE spoon)

• 1 ground (metal tent stake)

• Tie-down (550 Cord)

Preparation:

1. Figure length of wire using quarter wave formula. Double this measurement for half-wave length.

2. Measure and cut antenna wire.

3. Drill two holes in the MRE spoon.

4. Attach the antenna wire to the antenna well of the radio or the adapter on the AN/PRC-119A.

5. Attach other end of the antenna wire to the spoon.

6. Attach 550 cord to the other end of the spoon.

7. Run the wire up next to a tree and attach the cord to a branch.

8. Set the radio into operation.

Jungle Antenna
Range: 2 -3 x normal range

Materials Needed:

• 1 radio (AN/PRC-77, AN/PRC-119A with adapter)

• Wire (WD-1)

• 2 insulators (MRE spoon)

• 1 ground (metal tent stake)

• Tie-down (550 Cord)

• 3 spreader sticks (tree branches)

Preparation:

1. Figure length of wire using quarter wave formula.

2. Measure and cut four equal lengths of antenna wire.

3. Measure and cut three spread sticks equal to the wire length.

4. Drill two holes in the spoons.

5. Assemble the spread sticks into a triangle shape and tie together with 550 cord.

6. Attach a length of measured wire to each of the corners of the triangle. Take one of the insulators and attach the other end of the three wires to it leaving some excess (2-4 cm). Splice the three excess strands together. This assembly is called the ground plane.

7. Attach the last length of measured wire (vertical wire) to the other end of the insulator connected to the ground plane. Leave some excess (2-4 cm). Connect the opposite end to the other insulator.

8. To the opposite end of the insulator attach a length of 550 cord. This is the haul line.

9. Assemble the coax cable. Take two equal lengths of commo wire (no more than 45 feet) and twist them together with 6-10 twists per foot.

10. Attach one wire of the coax cable to the battery box. Attach the other end to the excess splice of the ground plane assembly or adapter on the AN/PRC-119A.

11. Attach the other wire of the coax cable to the antenna well of the radio. Attach the other end to the excess of the vertical wire assembly.

12. Run the haul line up and over a tree branch and secure the antenna in place.

13. Set the radio into operation.

Vertical Half-Rhombic Antenna
Range: 2 -3 x normal range

Materials Needed:

• 1 radio (AN/PRC-77, AN/PRC-119A with adapter)

• Wire (WD-1)

• 2 insulators (MRE spoon)

• 2 grounds (metal tent stake)

• 1 pole (10 meter tree or pole)

• 400-700 Ohm non-inductive resistor (BA-30 battery and nail)

Preparation:

1. Cut a 35 meters length of commo wire. Allow for excess.

2. Cut a pole approximately 10 meters.

3. Drill two holes in each spoon.

4. Assemble resistor by pounding a nail into each end of a fresh BA-30

5. Find center of 35 meter length of wire and attach to one end of the 10 meter pole.

6. Plant the pole into the ground.

7. Attach a spoon to each end of the 35 meter wire, leaving some excess. Attach the tie down to a ground stake.

8. Draw the antenna taut and pound the ground stake into the ground.

9. On the far end insulator, attach the excess wire from the antenna to one end of the resistor.

10. Run a length of wire from ground stake to ground stake. This is called the counterpoise to the other end of the resistor.

11. The angle formed by the antenna wire and the ground should be approximately 45-55 degrees.

12. Connect a ground wire from the battery box of the radio or adapter to the ground wire excess of the near side insulator.

13. Attach a 1½ meter maximum length of wire to the antenna well of the radio or adapter and fasten this to the antenna wire near side insulator, opposite the resistor.

14. Set the radio into operation

15. Remove the resistor to make the radio bi-directional.

Slant Wire Antenna
Range: 2 -3 x normal range

Materials Needed:

• 1 radio (AN/PRC-77, AN/PRC-119A with adapter)

• Wire (WD-1)

• 4 insulators (MRE spoon)

• 2 stakes (tent stakes)

Preparation:

1. Calculate the length of wire using the quarter wave formula.

2. Measure and cut two equal lengths of antenna wire.

3. Drill holes in each spoon.

4. Pound stakes into the ground.

5. Attach insulators to each end of both wires.

6. Attach the antenna wire to the stake on one end and a tree on the other end. Ensure the wire is at a 30-60 degree angle.

7. Attach the ground wire from one stake to the other. Ensure that the wire is taut and between ankle and knee high.

8. Attach a ground wire to the battery box of the radio or the adapter.

9. Attach a length of wire (1½ meters) to the antenna well of the radio or the adapter and fasten this to the excess antenna wire of the near side insulator.

10. Place the radio into operation.

Doublet Antenna
Range: 2 -3 x normal range

Materials Needed:

• 1 radio (AN/PRC-77, AN/PRC-119A with adapter)

• Wire (claymore)

• 1 insulator (MRE spoon)

• Coax wire

• 2 reels for claymore wire

Preparation:

1. Calculate the length of the wire using the quarter wave formula for 30.00 hz.

2. Measure and cut two equal length of antenna wire.

3. Attach one end of the wire to a coax cable and the other end to a reel cable.

4. Calculate the length for the frequency you will be using and roll out enough from the reel to equal that.

5. Hang the end of the antenna straight out with the broadside toward the receiving station.

6. Connect the coax to the radio and place the radio into operation.

Improvised Insulators

Best	Good	Fair
Plastic spoon (MRE spoon)	Dry wood	Cloth
Button (BDUs)	Dry rubber	Rope or 550 cord
Glass or plastic bottle neck
Plastic bag

Improvised Resistor
Use one of the following options to improvise a non-inductive 400-600 ohms resistor:

• Use a resistor rated at least one-half the wattage output of your transmitter (2-5 watts).

• Fresh BA-30 with nails driven into each end.

• Salt water filled ear plug case (old barrel type).

Wavelength Conversion Formula
This formula is used for determining antenna length. The FM frequency is in KHz.

Antenna Length (ft.) = 234/(FM frequency)

Example: FM frequency of 37.25 should yield an antenna length = 6'3".

III. Military Tactical Communication Equipment

Radio Sets

Wire Equipment

Antennas

Battery Life Charts