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the process of transmitting or the progress of signals after they have been transmitted.
Technology modifying analog signals
Make data suitable for carrying over communication path
Combined with another analog signal
Produces unique signal -Transmitted from one node to another
Purpose: Convey information
Signal transmission: both directions
One at a time
One communication channel
Shared for multiple nodes to exchange information
Transmitter assigns slots to nodes
According to priority, need
More efficient than TDM
FDM (frequency division multiplexing)
Unique frequency band for each communications subchannel
Cellular telephone transmission
DSL Internet access
WDM (wavelength division multiplexing)
One fiber-optic connection
Carries multiple light signals simultaneously
DWDM (dense wavelength division multiplexing)
Used on most modern fiber-optic networks
One transmitter and multiple, undefined receivers
Used on wired and wireless networks
Simple and quick
Most frequently discussed
Measures amount of data transmitted
During given time period
Capacity or bandwidth
Quantity of bits transmitted per second
Bandwidth (strict definition)
Measures difference between highest and lowest frequencies medium can transmit
Range of frequencies
Measured in hertz (Hz)
Digital signals sent through direct current (DC) pulses applied to wire
Requires exclusive use of wire's capacity
Transmit one signal (channel) at a time
Radiofrequency (RF) analog waves
Uses different frequency ranges
Does not encode information as digital pulses
Types of noise
EMI (electromagnetic interference)
EMI/RFI (radiofrequency interference)
NEXT (near end cross talk)
Potential cause: improper termination
Digital signals retransmitted in original form
Repeater: device regenerating digital signals
RTT (round trip time)
Time for packet to go from sender to receiver, then back from receiver to sender
Measured in milliseconds
Attneuation, Signal boosting Tech, Latency, Causes, RTT, May cause network transmission errors
Form of noise. Occurs when a signal traveling on one wire or cable infringes on the signal traveling over an adjacent wire or cable.
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