radio-frequency choke. An inductor (coil) with enough inductive reactance at radio frequencies to block the flow of RF alternating current. Either air or a slug of powdered iron may be used as the core of a radio-frequency choke.
radio-frequency oscillator. An electronic oscillator that changes direct current electricity into alternating current whose frequency is in the radio-frequency (RF) spectrum.
radio-frequency spectrum. The classification of frequencies of electromagnetic radiation usable for communications.
The bands of radio-frequency radiation used for communications and their commonly used names are:
Frequency Range Band Name
3 – 30 kHz--------------------------- Very Low Frequency (VLF)
30 – 300 kHz------------------------ Low Frequency (LF)
300 – 3,000 kHz--------------------Medium Frequency (MF)
3 – 30 MHz ------------------------- High Frequency (HF)
30 – 300 MHz ---------------------- Very High Frequency (VHF)
300 – 3,000 MHz------------------- Ultrahigh Frequency (UHF)
3 – 30 GHz --------------------------Superhigh Frequency (SHF)
30 – 300 GHz -----------------------Extremely High Frequency (EHF)
radio-frequency transformer. A transformer usable with alternating current in the radio-frequency (RF) spectrum. Most RF transformers have an air core.
radiographic inspection. A type of nondestructive inspection using X-rays and gamma rays to determine the condition of an aircraft structure at locations which could not otherwise be inspected without disassembly. Radiographic energy is passed through the structure and it exposes a photographic film or excites a fluorescent screen. Faults show up because their density is different from that of sound material.
radio marker beacon. A low-power, single-frequency (75-MHz), highly directional radio transmitter located at an important aviation navigation fix. The signal from a radio marker beacon is received only when the aircraft is directly above the transmitting antenna.
radiosonde. A device consisting of a group of meteorological instruments and a radio transmitter carried to a high altitude by a weather balloon. The instruments in the radiosonde measure the air pressure, temperature, and humidity and transmit this information to weather stations on the ground.
radio telegraphy. The method of radio communications in which information is transmitted by long and short spurts of radio-frequency energy. Radio telegraphy normally uses the International Morse Code. See International Morse Code in Appendix 4.
radio transmitter. An electronic device that transmits information by means of electromagnetic waves. The transmitter consists of an oscillator, a modulator, and an amplifier. The oscillator produces a carrier wave of the proper radio frequency. The modulator impresses the information to be transmitted onto the carrier, and the modulated carrier wave is amplified and delivered to an antenna from which it radiates into space.
|
