Annex B16 SCR TACSAT Flashcards
Satellites Footprint
Area of comm coverage on the earth’s surface
It is the portion of the earth that is effectively irradiated by that antenna and is determined by the type of orbit and the antenna’s directionality and size
It is the area with which a satellite can communicate
Three (3) components of a satellite
Transceiver
Antenna
Power Generator
Type of orbit predominately used with SATCOM
Geostationary
Three (3) segments of a typical satellite comm system
Space segment
Ground Segment
Control Segment
Advantages of SATCOM
- Satellite links are unaffected by the propagation variations that interfere with HF radio
- Free from high attenuation of wire or cable facilities
- Capable of spanning long distances
- Higher bandwidth links with higher fidelity
- Not dependent upon refraction/reflection
- Only slightly affected by atmospheric phenomena
- Destruction of a single satellite would be difficult and expensive
- High degree of freedom from jamming
- Lower probability of both detection/interception (LPD/LPI)
Two (2) single channel radio TACSAT bandwidths/waveforms most commonly used by USMC multiband radios
5 KHz/25 KHz (DED/DAMA)
Demand Assigned Multiple Access (DAMA)
Increase loading of limited SATCOM channels by assigning channels as needed by terminal users for their comm needs
Goes to users of highest priority first, can be kicked off if higher priority
Two (2) addresses required for DAMA
Terminal Base Address
Network Address
Characteristics of Time Division Multiple Access (TDMA)
Divides the signal into different time slots. The users transmit in rapid succession, one after the other, each using their own time slot
TDMA is the channel access method used with DAMA
All the bandwidth, some of the time
Characteristics of Frequency Division Multiple Access (FDMA)
FDMA gives users an individual allocation of one or several entire frequency bands within a channel
Provides users a small amount of bandwidth all of the time
