Radio Navigation Flashcards
Cycle
Interval between any 2 points measuring the completion of a single wave movement
Diffraction
Bending which occurs when a wave grazes the edge of a solid object through which it cannot pass
Attenuation
- Loss of wave as it travels through a medium
- Example is driving away from a radio station
Ionosphere
- Layer of rarified ionized gas believed to be caused by ultra-violet solar radiation
- Ranges from 60 to 200 miles above the earth and vary according to time of day, season, and latitude
Ground Waves
- Parts of the transmitted radiation that follows the surface of the earth
- Not subject to ionospheric interference or weather
- Suffers from surface attenuation proportional to the frequency
- Lower frequencies = less attenuation
Space Waves
Parts of the transmitted radiation that travel directly into space
Sky Waves
- Parts of the transmitted radiation that is reflected or refracted from the ionosphere
- Continues to reflect between the earth and sky until completely attenuated
- Skip Zone
- The distance between the end of the useful ground wave and the point where the sky wave is returned to earth
Ground Waves Radio Frequency Categories
- Very Low Frequency (VLF)
- Low Frequency (LF)
- Medium Frequency (MF)
Sky Waves Radio Frequency Categories
High Frequency (HF)
Space Waves Radio Frequency Categories
- Very High Frequency (VHF)
- Ultra High Frequency (UHF)
- Super High Frequency (SHF)
- Extremely High Frequency (EHF)
- Line of sigh transmission
- Signals not affected by time of day, season, precipitation, or atmospheric conditions
Characteristics of VHF Signals
- Do not follow the curvature of the earth
- Do not bend around obstructions
- Primarily space waves
- Reception is limited by line of sight
VHF Omnidirectional Range (VOR)
- Frequency Range is 108.1-117.95 MHz (VHF)
- 3 letter morse code identifier
- Transmits 2 signals, a reference phase and variable phase
- Beacon rotates at 6 RPM, green light flashes the instant the beacon passes magnetic north
- Actual VOR does this electronically
- Beams emitted by VOR called radials
VOR components - Omni Bearing Selector (OBS)
Selects Desired Radial
VOR components - Course Deviation Indicator (CDI)
- Shows aircraft position relative to selected radial
- Each dots equals 2 degrees up to a maximum of 10 degrees either side of radial
VOR components - Sense Indicator (TO/FROM)
Indicates whether the aircraft is the TO or FROM side of the VOR
VOR interpretation
- VOR interpretations are dependant only on the position relative to the selected radial
- Rule of thumb is that in order to properly navigate, the heading and the OBS must agree or else reverse sensing will occur
VOR Homing (Direct to VOR site)
- Tune to proper frequency
- Confirm proper morse code using IDENT
- Rotate OBS knob to obtain a TO indication
- Rotate the OBS until the CDI centers with a TO indication
- Fly the heading under the OBS indicator
- Adjust heading as needed to keep CDI centered