Reconnaissance and Surveillance Leaders Course
RECONNAISSANCE & SURVEILLANCE LEADERS COURSE
RECONNAISSANCE & SURVEILLANCE LEADERS COURSE
RECONNAISSANCE AND SURVEILLANCE COMMUNICATIONS
RECONNAISSANCE AND SURVEILLANCE COMMUNICATIONS
Reconnaissance and Surveillance Leaders Course
RECONNAISSANCE AND SURVEILLANCE
COURSE
HF COMMUNICATIONS
RADIO WAVE PROPAGATION
Reconnaissance and Surveillance Leaders Course
THE CHALLENGES FACING YOU, THE HF RADIO OPERATOR, ARE TREMENDOUS!
Radio Wave Propagation
AS SELECTED LEADERS YOU MUST:
• POSSES MORE THAN A WORKING KNOWLEDGE OF YOUR EQUIPMENT
• BE ABLE TO ANSWER YOUR SUBORDINATES QUESTIONS
Reconnaissance and Surveillance Leaders Course
TERMINAL LERNING OBJECTIVE
Action: Implement the principles of Radio Wave Propagation
Condition: Denied the use of references
Standard: Answer test questions correctly that pertain to Radio Wave Propagation
Reconnaissance and Surveillance Leaders Course
Administrative
Safety: In an emergency, please exit through the exit doors and get a headcount outside in the parking lot
RiskAssessment: Low
Environmental
Considerations: If you brought it in, take it with you!
Note: Do not be afraid to ask questions or participate in discussion, just raise your
hand before speaking.
Reconnaissance and Surveillance Leaders Course
Evaluation
• You will be evaluated on this subject on Wednesday and during the STX/FTX
• You will be given a 50 question test
• You must correctly answer 35 out of 50 to receive a go
Reconnaissance and Surveillance Leaders Course
ENABLING LERNING OBJECTIVE #1
Action: Identify principles of Ground Wave Propagation
Condition: Denied the use of references
Standard: To receive a go, the student must take a 50 question multiple choice test and answer 35 questions correctly
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
• To understand Radio Wave Propagation, you must first understand what propagation is and some of the basic properties that affect propagation.
• Many of these properties are common everyday occurrences that you may already be familiar with
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
AS YOU WILL LEARN BY STUDYING THIS
SUBJECT,RADIO WAVES PROPAGATE OR SPREAD
OUT
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
Q: WHAT WERE SOME EARLY METHODS TO EXTEND COMMUNICATIONS RANGE?
•HAND AND ARM GESTURES
•BEATING ON A HOLLOW LOG
•SMOKE SIGNALS
•COURIER AND POSTAL SYSTEM
•STILL NEEDED TO EXTEND RANGE AND SPEED
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
DURING THE LATTER PART OF THE 19th CENTURY BOTH SPEED AND DISTANCE WERE GREATLY OVERCOME WITH:
•THE INVENTION OF THE TELEGRAPH
• THE INVENTION OF THE RADIO TRANSMITTER
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
• HEINRICH HERTZ Discovered how to send a message in the form of a radio wave:
•This is where the term “Hertz” comes from
•One Hertz is one cycle per second:
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
• A radio wave that has a frequency of 2 KHZ cycles at 2000 times a second
• 2 MHZ cycles at 2,000,000 times a second
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
VLFLFMFHF
VHF
UHF
SHF
EHF
COSMICGAMMA
3000 Hz (3 KHz)
30,000 Hz (30 KHz)
300,000 Hz (300 KHz)
3,000,000 Hz (3 MHz)
30 MHz
300 MHz
3 GHz
30 GHz
300 GHz
3 THz
300,000 THz
MILITARY COMMUNICATIONS
RADARMICROWAVES
INFRA-RED
VISIBLE LIGHTULTRA-VIOLET LIGHT
X-RAY
T = TERAG = GIGAM = MEGAK = KILO
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
• A well designed, properly maintained LOS radio system will operated day after day, year after year with little or no significant outages
• Even if an HF radio system is well designed, the operator must continually adjust the system to compensate for changing terrestrial environment
However…….
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
• High Frequency (HF)radio waves travel by two primary means:
Reconnaissance and Surveillance Leaders Course
Ground Wave Propagation
• Ground waves are affected by three factors:
1. Electrical characteristics of the earth
-Ground is negative
-Path of least resistance
2. Power output & frequency of the transmitter
- More power and higher frequency= further ground wave distance
3. Shape and conductivity of the earth
-Obstacles in transmission path?
Reconnaissance and Surveillance Leaders Course
Ground Wave Propagation
•Obstacles include:
• Mountains
•Cliffs
•Vegetation
•Man-Made Objects
Reconnaissance and Surveillance Leaders Course
Ground Wave Propagation
•There are three components to a ground wave:
Direct Wave
Ground Reflected Wave
Surface Wave
Reconnaissance and Surveillance Leaders Course
Ground Wave Propagation
Direct Wave
• Travels directly from transmit to the receive antenna
• Limited by LOS distance
•Distance can be extended by raising the transmit or receive antenna
Reconnaissance and Surveillance Leaders Course
Ground Wave Propagation
Ground Reflected Wave
• Reaches the receiving antenna after being reflected by the surface of the earth
Reconnaissance and Surveillance Leaders Course
Ground Wave Propagation
Surface Wave
• Follows the curvature of the earth until it is too weak to be received or encounters an obstacle
Reconnaissance and Surveillance Leaders Course
Ground Wave Propagation
Reconnaissance and Surveillance Leaders Course
Ground Wave Review
Q: What are the three components to a ground wave?A: Direct Wave, Ground Reflected Wave and Surface Wave
Q: What obstacles can impede the path of a ground wave?A: Mountains, power lines, steep cliffs, heavy vegetation and man-made objects
Q: What other factors influence how far a ground wave will propagate?
A: Transmitter power and frequency (Hertz)
Reconnaissance and Surveillance Leaders Course
Reconnaissance and Surveillance Leaders Course
Radio Wave Propagation
Q: We know that an HF radio wave will travel on or near the ground, what other way can an HF radio wave propagate?
A: Through the atmosphere, called a “Sky Wave”
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
Reconnaissance and Surveillance Leaders Course
ENABLING LERNING OBJECTIVE #2
Action: Identify principles of Sky Wave Propagation
Condition: Denied the use of references
Standard: To receive a go, the student must take a 50 question multiple choice test and answer 35 questions correctly
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
• Sky wave propagation uses the earth’s atmosphere as it’s medium
• You must be familiar with the different parts of the atmosphere and how it effects the propagation of radio waves
• Long Range Surveillance teams rely heavily on sky wave propagation to communicate intelligence and complete their mission
Reconnaissance and Surveillance Leaders Course
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
• High Frequency (HF) communications rely on portions of the atmosphere for long range communications
• The atmosphere varies with altitude, geographic locations, time of day and season
• There are three layers of the atmosphere, which will be discussed later in detail
Q: How far do you think you can communicate using sky wave propagation?
A: Unlimited
Reconnaissance and Surveillance Leaders Course
Sky Wave PropagationIONIZATION
• AN ATOM IS NEUTRALITY CHARGED
• IONIZATION OCCURS WHEN:
THE SUN’S ULTRAVIOLET LIGHT WAVES STRIKE A GAS ATOM, AND LITERALLY KNOCK AN
ELECTRON FREE FROM ITS PARENT ATOM CREATING A LAYER OF OPPOSITELY CHARGED PARTICLES
• THIS LAYER ALLOWS HF RADIO WAVES TO BE REFRACTED BACK TO EARTH
Reconnaissance and Surveillance Leaders Course
IONIZATION
Reconnaissance and Surveillance Leaders Course
Sky Wave PropagationIONIZATION
• There are certain locations, seasons and times of day when there is more of the sun striking the atmosphere.
Q: What season do you think ionizations occurs at a greater level?
A: Summer
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
RECOMBINATION
• SINCE IONIZATION ONLY HAPPEN DURING DAYLIGHT, A REVERSE PROCESS CALLED RECOMBINATION OCCURS AT NIGHT.
• EVENTUALLY, DO TO THE ABSENCE OF UV RAYS ,ELECTRONS WILL MERGE WITH THE PARENT ATOMS CAUSING A NEUTRAL STATE
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
Q: What are the three layers of the atmosphere?
Troposphere
Stratosphere
Ionosphere
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
TROPOSPHERE
• 4 TO 11 MILES ABOVE THE EARTH
• ALL WEATHER TAKES PLACE
• CLOUDS FORM
• TURBULENCE
• TEMPERATURE VARIES
HAS A GREAT EFFECT ON THE PROPAGATION OF RADIO WAVES
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
STRATOSPHERE
• BETWEEN TROPOSPHERE AND IONOSPHERE
• CONSTANT TEMPERATURE
• LITTLE WATER VAPOR
HAS RELATIVELY NO EFFECT ON RADIO WAVES
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
IONOSPHERE
• 30 - 250 MILES ABOVE THE EARTH
• FOUR CLOUD-LIKE LAYERS
• USED FOR LONG DISTANCE COMMUNICATIONS
MOST IMPORTANT REGION OF THE ATMOSPHERE
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
Q: We know that the Ionosphere is composed of 4 cloud like layers. Can anybody name some of these layers?
• Four distinct layers during the day-
• One layer at night- F
D E F1 F2
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
D REGION
• EXISTS ONLY DURING DAYLIGHT HOURS
• IONIZATION IS LOW BECAUSE THE E & F LAYERS HAVE ALREADY ABSORBED MOST OF THE UV RAYS
• HIGH FREQUENCIES PASS RIGHT THROUGH IT
D LAYER HAS LITTLE EFFECT ON HF RADIO WAVES
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
E REGION
• EXISTS ONLY DURING DAY LIGHT HOURS
• USED FOR HF RADIO TRANSMISSIONS LESS THAN 1500 MILES
• KNOWN AS THE KENNELLY-HEAVISIDE LAYER
• CAN REFRACT FREQUENCIES UP TO 20 MHZ
Reconnaissance and Surveillance Leaders Course
Sky Wave PropagationF REGION
• IONIZED ALL OF THE TIME
• TWO LAYERS DURING THE DAY (F1 AND F2)
• ONE LAYER AT NIGHT (F)
• RESPONSIBLE FOR HF LONG RANGE COMMUNICATIONS GREATER THAN 1500 MILES
• EXTREMELY USEFUL LAYER FOR HF COMMUNICATIONS
Reconnaissance and Surveillance Leaders Course
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
Reconnaissance and Surveillance Leaders Course
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
Variations in the Ionosphere
• Regular: Variations that scientists can predict because they happen at regular intervals:
• Seasonal Variations -Summer/Winter
• 11 year Sunspot Cycle –An 11 year cycle in which sunspot activity increases or decreases. Sunspots increase ionization.
• 27 Day Sunspot Cycle –It takes the sun 27 days to rotate on its axis, increasing and decreasing ionization
Reconnaissance and Surveillance Leaders Course
Sky Wave PropagationVariations in the Ionosphere
Irregular Variation: These are the variations that cannot be predicted, but are known to occur:
• Sporadic E- Irregular cloud like patches of unusually high ionization, often in the E region. Cause is unknown, and varies significantly with latitude.
• Sudden Ionosphere Disturbance (SID) –Occur without warning and may last several hours. Long distance HF propagation is totally blanked out.
• Ionospheric Storms –Caused by disturbances in the Earth’s magnetic field. Are tied solar eruptions and occur 18 hours after a SID.
Reconnaissance and Surveillance Leaders Course
Reconnaissance and Surveillance Leaders Course
SKY WAVE PROPAGATION:
• DEPENDS UPON THE IONOSPHERE TO PROVIDETHE SIGNAL PATH BETWEEN THE TRANSMIT ANTENNA AND THE RECEIVE ANTENNA
• THE IONOSPHERE BENDS THE RADIO WAVE BACK TO EARTH, THIS BENDING IS CALLED REFRACTION
Sky Wave Propagation
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
THE AMOUNT OF REFRACTION DEPENDS ON THREE MAIN FACTORS:
1. THE DENSITY OF IONIZATION IN A PARTICULAR REGION
2. THE FREQUENCY OF THE RADIO WAVE
3. THE ANGLE AT WHICH THE WAVES ENTER THE REGION
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
Station A Station B
MAXIMUM ELECTRON DENSITY
SignalAngle of Incidence
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
Q: What do you think the area between Station A and Station B is called
A: Skip Distance
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
Skip Zone is the area of silence between the point where the ground wave becomes too week and the sky wave returns to earth
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
ABSORPTION IN THE IONOSPHERE
• PROVIDES THE GREATEST ADVERSE EFFECT ONRADIO WAVES
• EFFECTS BOTH THE STRENGTH OF RECEIVED SIGNALS AND THE ABILITY TO COMMUNICATE OVER LONG DISTANCES
Reconnaissance and Surveillance Leaders Course
Sky Wave Propagation
REFERENCES:
o Student Handout
o FM 11-65
o FM 11-64
o FM 24-18
Reconnaissance and Surveillance Leaders Course
Review/Summary
• The Terminal Learning Objective is to identify the principles of Radio Wave Propagation (RWP). When tested you will be denied the use of references and must answer 35 out of 50 questions correctly.
Reconnaissance and Surveillance Leaders Course
QUESTIONS?
Reconnaissance and Surveillance Leaders Course
Review/Summary
1. What are the three parts of a ground wave?
Direct Wave, Ground Reflected Wave, Surface wave
2. What is refraction?
Ionosphere bending a radio wave back to earth
3. What are the three irregular ionospheric variations?
Sporadic E, Sudden Ionospheric Disturbance (SID) and Ionospheric Storms
Reconnaissance and Surveillance Leaders Course
Review/Summary
We have just covered principles of Radio Wave Propagation. Our next lesson will cover Antenna Theory