HF Communications
- Introduction
- History of HF communications
- Terrestrial wireless communications challenges: Attenuation, reflection, diffraction, scattering, multipath effects, interference
- Spectrum Basics
- Electromagnetic spectrum: Bands and uses, regulation
- More about the HF band
- Spectrum issues: Line of Sight (LOS) transmission, path loss, etc
- Radio Propagation
- Electromagnetic field
- Ground and surface waves: What, when
- Direct waves: Direct LOS, Fresnel theory, free space loss, sum operating margin
- Sky waves (Ionosphere)
- Key concepts
- Structure of the Ionosphere: D, E, F1, F2
- Critical frequencies: MUF, LUF
- Propagation effects: Daily, seasonal, geographic, sunspots, interference, weather, solar flares
- Propagation indices: K, Ap, Solar flux, Sunspot number
- Tropospheric waves
- Antennas
- Characteristics: Dimensions, gain (dB), polarization, F/B ratio, VSWR, radiation diagrams, HPB
- Types: Directional, omnidirectional
- Whip, dipole, inverted Vee, Loop, beams
- Practical examples
- Modulation and Communication Modes
- Modulation
- Analog: AM, SSB, FM, PM
- Digital: xFSK, xASK, xPSK, xQAM
- Modes
- CW-Morse
- AM voice/SSB voice
- FM voice
- Digital: Modems/examples
- HF Radios
- Types: Analog, digital, portable, vehicle, nomadic, fixed
- Types: analog, digital, portable, vehicle-mounted, nomadic, fixed
- Architecture
- Characteristics
- Power
- Channels
- Modulation
- Uses of HF Communications
- Long distance/amateur radio
- Emergency (including disasters) communications
- Maritime uses
- Military applications
- Examples
- Link Budget Calculations
- Basic principles
- Tools
- Calculation exercise
- Emerging Trends
- Automatic link establishment
- Digital new services
- Conclusion
- Comparison of satellite and HF communications
- Advantages and disadvantages
- Course recap, Q/A, and Evaluations
