01 Intro to comms

Question 1

Communication principles

Answer 1

Communications principles
The transfer of meaningful information from one location to another
Signal selected must appropriately represent the transferred information
Available medium must be able to support the chosen communications method
Meaning of the signal must not be lost despite the influence of factors
Meaningful information = knowledge = power
Provide friendly forces with the intended information, while denying that information to the enemy
Defensive – All activities and measures that ensure that friendly forces can communicate, and prevent enemy forces from listening to or interfering with our communications
Offensive – All activities and measures that deny enemy forces the ability to communicate successfully

Question 2

Desired comms characteristics

Answer 2

Fidelity 
Interoperability
Reliability
Security
Timeliness
Completeness 
Accuracy
Survivability
Affordability
Availability

Question 3

Communications modes (3)

Answer 3

Simplex – one direction
Half Duplex – both directions (only one at a time)
Full Duplex – Both directions (same time)

Question 4

Energy Forms

Answer 4

For communications to exist, electrical energy is modulated from its base form to contain information. A modulated signal propagates as EM wave through long distance metallic wires and unbounded mediums such as fibre optics, waveguides, and for wireless transmissions.

Question 5

Communications methods

Answer 5

Bounded vs Wireless
Analogue vs Digital
Voice vs Data

Question 6

Signal types
Form
Carrier signal
Frequency coverage

Answer 6

Form: Analogue or digital
Carrier signal (baseband or modulated)
Frequency coverage (narrow band less than 1.544mbps or wideband more than 1.544mbps)

Question 7

Characteristics of carrier signals

Answer 7

Amplitude (strength)
Frequency
Phase

Question 8

Bandwidth

Answer 8

Band of frequencies or spectrum space occupied by a signal

Difference between the highest frequency component and the lowest frequency component of the signal spectrum

Question 9

Desired communication Characteristics

Answer 9

transmission Time
Bandwidth
Amount of information
(Triangle)

Question 10

Communications obstacles

Answer 10

Noise
Distortion
Attenuation
Interference
Multipath fading

Question 11

Solution to comms obstacles
Limited bandwidth
Noise
Distortion
Attenuation
Interference
Multipath fading

Answer 11

Limited bandwidth
     Compression and truncation of the data
     Increase network capacity i.e. wider bandwidth and more transmission means
Noise
     Physically cooling equipment
     Limiting bandwidth and operating at frequency  bands less subjected to noise
Distortion
     Using FM over AM
     Digital
Attenuation
     Transmitted power
     Receiver sensitivity
     Antenna gain
Interference
     Improving transmission lines
     Medium and frequency diversity
Multi path fading
     Alter receiver antenna (choke, ring, directional)
     Frequency diversity