Radio Theory

Radio and Electronic Theory Radio communication is a very important part of general aviation, but for RPAS it becomes even more important because the control of the aircraft is heavily dependent on Radio. Radio Signals transmit the control inputs from the pilot to aircraft transmit feedback information back to the pilot often transmit video signals between pilot and aircraft Radio waves are part of the Electromagnetic Spectrum (which includes visible light, microwaves, and X-rays) relative to other electromagnetic waves, radio waves have long wavelengths and low frequencies - and therefore relatively low energy. Waves frequency and wavelength are inverses of each other: Wavelength = C/Frequency) C being the speed of propagation (300,000,000 m/s) and so lower frequency waves will have a longer wavelength Radio Waves can be sub-classified by their wavelengths and frequencies into: Low frequency / medium frequency High frequency Very hight frequency Ultra high frequency Super high frequency

Low Frequency / Medium Frequency (LF/MF) Low frequencies (30 KHz to 3000 KHz) have the largest wavelengths from 100m to 10km. They are used by commercial AM radio stations as well as by: • Non-directional beacons (NDBs) • Marker Beacons

High Frequency (HF) HF radio is used for long range air and ground communications especially trans-oceanic or in the Arctic, however the range is dependent upon the ionosphere which can change between daytime and night time. High Frequency waves (3000 KHz to 30000 KHz) have a wavelengths from 10m to 100m; they use: 5680 kHz is used frequently in northern Canada where VHF communications cannot be established HF is also utilized on Trans-Atlantic flights