Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
70 Cards in this Set
- Front
- Back
|
Volt
|
Electrical current pressure
|
|
|
Analog data signals
|
Voltage varies continuously
|
|
|
Properties of Analog signals
|
Amplitude, frequency, wavelength, phase
|
|
|
Amplitude
|
Analog wave’s strength
|
|
|
Frequency
|
-Number of times amplitude cycles over fixed time period
-Measure in hertz (Hz) |
|
|
Wavelength
|
-Distance between corresponding wave cycle points
-Inversely proportional to frequency -Expressed in meters or feet |
|
|
Phase
|
Wave’s progress over time in relationship to fixed point
|
|
|
Analog signal benefit over digital
|
-More variable
-Convey greater subtleties with less energy |
|
|
Drawback of analog signals
|
-Varied and imprecise voltage
-Susceptible to transmission flaws |
|
|
Pulses of voltages
|
-Positive voltage represents a 1
-Zero voltage represents a 0 |
|
|
Digital signal benefit over analog signal
|
-More reliable
-Less severe noise interference |
|
|
Digital signal drawback
|
Many pulses required to transmit same information
|
|
|
Overhead
|
-Nondata information
-Required for proper signal routing and interpretation |
|
|
Data relies on what?
|
digital transmission
|
|
|
What kind of signals can network connections only handle?
|
analog signals
|
|
|
A modem does what and is what?
|
-Accomplishes translation
-Modulator/demodulator |
|
|
Data modulation
|
Technology modifying analog signals
|
|
|
Carrier wave
|
-Combined with another analog signal
-Produces unique signal Transmitted from one node to another |
|
|
What is the purpose of a carrier wave?
|
Convey information
|
|
|
Information wave (data wave)
|
-Added to carrier wave
-Modifies one carrier wave property |
|
|
Frequency modulation
|
-Carrier frequency modified by application of data signal
-Makes it conform to a specific pathway |
|
|
Amplitude modulation
|
-Carrier signal amplitude modified by application of data signal
|
|
|
Simplex
|
Signal transmission
|
|
|
What direction does simplex travel?
|
One direction
|
|
|
Half Duplex
|
Signal transmission
|
|
|
What direction does half-duplex travel?
|
-Both directions (one at a time)
-One communication channel -Shared for multiple nodes to exchange information |
|
|
What direction does Full-duplex travel? And where is it used?
|
-Both directions simultaneously.
- Used on data networks |
|
|
Channel
|
-Distinct communication path between nodes
-Separated physically or logically |
|
|
What is the advantage of Full duplex?
|
Increases speed
|
|
|
Multiplexing
|
Multiple signals travel simultaneously over one medium
|
|
|
Subchannels
|
Logical multiple smaller channels
|
|
|
Multiplexer
|
Combines many channel signals
|
|
|
What is the abbreviation for Multiplexer?
|
mux
|
|
|
Demultiplexer
|
- Separates combined signals
- Regenerates them |
|
|
What is the abbreviation for Demultiplexer?
|
demux
|
|
|
time division multiplexing
|
Divides channel into multiple time intervals
|
|
|
Statistical multiplexing
|
-Transmitter assigns slots to nodes according to priority, need
|
|
|
Is TDM more efficient then Statistical multiplexing?
|
No. Statistical multiplexing is more efficient than TDM.
|
|
|
What is the abbreviation for time division multiplexing?
|
TDM
|
|
|
Frequency Division Multiplexing
|
Unique frequency band for each communications subchannel
|
|
|
What are the types of frequency division multiplexing?
|
- Cellular telephone transmission
- DSL Internet access |
|
|
Wavelength Division Multiplexing (WDM)
|
-One fiber-optic connection
-Carries multiple light signals simultaneously |
|
|
Dense Wavelength Division Multiplexing (DWDM)
|
- Used on most modern fiber-optic networks
- Extraordinary capacity |
|
|
Point-to-point transmission
|
One transmitter and one receiver
|
|
|
Point-to-multipoint transmission
|
One transmitter and multiple receivers
|
|
|
Broadcast transmission
|
One transmitter and multiple, undefined receivers
|
|
|
What is broadcast tranmisson used on?
|
- wired and wireless networks.
- simple and quick. |
|
|
Nonbroadcast
|
One transmitter and multiple, defined receivers
|
|
|
Throughput
|
Capacity or bandwidth
|
|
|
Bandwidth (strict definition)
|
Measures difference between highest and lowest frequencies medium can transmit
|
|
|
Baseband transmission
|
Digital signals sent through direct current (DC) pulses applied to wire
|
|
|
Give an example of baseband transmission.
|
Ethernet
|
|
|
Broadband transmission
|
- Radiofrequency (RF) analog waves
- Uses different frequency ranges |
|
|
Noise
|
Any undesirable influence degrading or distorting signal
|
|
|
EMI (electromagnetic interference)
|
EMI/RFI (radiofrequency interference)
|
|
|
Cross Talk
|
near end cross talk (NEXT)
|
|
|
What is a potential cause for cross talk?
|
improper termination
|
|
|
Environmental influences
|
Heat
|
|
|
List transmission flaws.
|
1. EMI,
2. Cross talk, 3. Environmental influences. |
|
|
Attenuation
|
Loss of signal’s strength as it travels away from source
|
|
|
Signal boosting technology
|
Analog signals pass through amplifier
|
|
|
What is also amplified in signal boosting technology?
|
Noise.
|
|
|
Regeneration
|
Digital signals retransmitted in original form
|
|
|
What device is used in digital signal regeneration?
|
A repeater.
|
|
|
What OSI layer do amplifiers and repeaters fall under?
|
Layer 1 : Physical Layer
|
|
|
Latency
|
Delay between signal transmission and receipt
|
|
|
What causes latency?
|
- Cable length
- Intervening connectivity device |
|
|
Round trip time (RTT)
|
Time for packet to go from sender to receiver, then back from receiver to sender
|
|
|
How is Round Trip Time measured?
|
In milliseconds
|
|
|
What are the characteristics of physical media?
|
1. Throughput
2. Cost 3. Size and scalability 4. Connectors 5. Noise immunity Teaching Can Sure Cause Noise. |
