Theory Flashcards
What are the three basic elements of communications systems?
- sender
- medium
- receiver
Definition of military comms
The rapid transfer of information between military units and the authorities that control them.
Define tactical communications
Tactical communications is communications between two or more mobile units; typically carried out at short range, conveying operationally important information.
Definition of military communications
The rapid transfer of information between military units and the authorities that control them.
What is a bearer?
A physical link such as copper wires or fibre optic cables.
What is a medium?
Sound waves need a medium to travel through. This is typically the atmosphere, although sound waves can also travel through water.
Define a radio communications system
A radio communications system uses the medium of radio waves to transmit and receive information.
Define propagation
The way in which radio waves travel through the earths atmosphere or space.
Define the term emission designator
An internationally recognised shorthand that accurately describes the construction of an emission.
Define the RATT parameter shift
The shift is the difference in frequency between the two RATT tones in Hertz
Define strategic communications
Communications with units and authorities which require the use of shore stations and convey administrative and operational information.
Strategic communications are typically long range and involve worldwide coverage.
3 main types of radio modes used in the RFA?
Voice
RATT - Radio Automatic TeleType
Data
What is the purpose of a transducer?
A device which converts information such as sound into an electrical signal suitable for transmission over a line or via radio
What are the two types of electromagnetic waves?
Radio Waves & Microwaves
What are the 3 main baseband types used in the RFA?
Voice
RATT
Data
Why do we offset?
To centre our emission around the assigned bandwidth
Define the frequency selected carrier
The FSC is the frequency which is selected on the radio equipment. Also know as the window frequency or dial set.
What is the formula for FSC?
FSC = Fa - offset
What is the formula for offsetting RATT?
(A + Z) / 2
What are the rules for offsetting voice?
- 1.5 kHz, or if the Fa ends in 0.4 kHz, - 1.4 kHz
When do Ground waves occur?
HF and below
When does sky wave propagation occur?
MF & HF frequencies
When does direct/ space wave propagation occur?
VHF frequencies and above
