ecomms Flashcards
Basic Components
a transmitter, a communication channel (medium), and a receiver.
is an interference that degrades the transmitted
information.
noise
Converts the message into an electronic signal suitable for transmission.
transmitter
Electrical Conductors
Includes wires, coaxial cables, and twisted-pair cables.
Fiber-optic cables carry messages using light waves, commonly
used for long-distance communication.
Optical Media
nterferes with the communication process and is a significant issue in
receivers.
Noise
FreeSpace
Radio (wireless communication) uses the electromagnetic spectrum
to transmit signals through electric and magnetic fields.
Other Media
Includes sonar (using water), the earth itself, and AC power lines
(carrier current transmission or power line communications)
Receiver
Converts the transmitted signal back into a human-understandable form.
Signal degradation occurs over distance and is proportional to the square
of the distance.
Attenuation:
Transceivers:
These are devices that can both transmit and receive signals, commonly
found in phones, radios, and modems.
Two-way communication where both parties can transmit and
receive simultaneously, such as in telephone conversations.
Full Duplex
are continuously varying voltages or currents
Analog Signals
ASCII
American Standard Code for Information Interchange
Two-way communication where transmission is alternated between
parties.
Half Duplex:
are the original information signals, whether analog
or digital.
Baseband Transmission
change in discrete steps or increments and typically
use binary (two-state) codes.
Digital Signals
Allows multiple signals to be transmitted simultaneously over a
single communication medium, increasing efficiency
Multiplexing
Digital Modulation Techniques:
Frequency-Shift Keying (FSK): Phase-Shift Keying (PSK)
A technique that makes information signals compatible with the
transmission medium by modifying a carrier signal with the baseband signal
Modulation
The process at the receiver end to extract the original baseband
signal from the modulated carrier signal.
Demodulation:
The baseband signal varies the amplitude of the
carrier signal.
Amplitude Modulation (AM)
The baseband signal varies the phase angle of the
carrier signal
Phase Modulation (PM)
Involves modifying a carrier signal using the baseband signal to
create a broadband signal for transmission.
Modulation Process
The baseband signal varies the frequency of the
carrier signal
Frequency Modulation (FM)
Signals are sampled sequentially, and
pieces of each are transmitted in turn, allowing reconstruction at the receiving
end.
Time-Division Multiplexing (TDM):
Each signal modulates a subcarrier at
a different frequency, and all are combined for transmission.
Frequency-Division Multiplexing (FDM)
Signals are converted to digital data,
uniquely coded, and transmitted simultaneously on the same frequency. Unique
codes are used at the receiver to select the desired signal
Code-Division Multiplexing (CDM)
located above the millimeter-wave region, includes infrared,
visible, and ultraviolet light
The Optical Spectrum
are essential for ensuring compatibility between different
communication systems.
Standards
Higher frequencies allow for more channels and wider
bandwidths for signals like TV broadcasts, which require a 6 MHz bandwidth
Spectrum Utilization
When information is modulated onto a carrier frequency, the
signal occupies a certain portion of the spectrum around that carrier frequency,
including sidebands generated by modulation.
Channel Bandwidth
The electromagnetic spectrum is a finite resource. To manage
it effectively, governments set up agencies to control its use.
Spectrum Management
300-3000 MHz, used in TV, mobile phones, and
radar.
Ultrahigh Frequencies (UHFs)
refers to the range of frequencies within the
electromagnetic spectrum that a signal occupies.
Bandwidth
(NTC)
National Telecommunications Commission
(DICT)
Department of Information and Communications Technology
Challenges
Infrastructure Gaps:
Service Quality:
Regulatory Hurdles
Digital Divide:
Future Outlook
Infrastructure Development:
Increased Competition
Digital Transformation
Electronic communication is integral to modern life, with a variety of applications that
most people are already familiar with, such as telephones
Communication Applications
