The lowest layer of reference model. It defines the mechanical, electrical, and timing interfaces to the network. Chapter 2 The Physical Layer. BANDWIDTH AND INFORMATION CAPACITY.
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The lowest layer of reference model. It defines the mechanical, electrical, and timing interfaces to the network.
Chapter 2 The Physical Layer
Bandwidthis the span of frequencies within the spectrum occupied by a signal and used by the signal for conveying information.
Carrying information requires bandwidth.
L is the number of signal levels used to represent data.
Increasing the levels of a signal may reduce the reliability of the system.
The theoretical highest data rate for a noisy channel
where capacity is in bits/second, bandwidth is in hertz, and signal and noise powers are measured in the same physical units, such as watts. Bits are fundamental units of information.
The Shannon capacity gives us the upper limit;
the Nyquist formula tells us how many signal levels we need.
Category 5e UTP cable with four twisted pairs
A coaxial cable
A network that uses household electrical wiring.
(a) Side view of a single fiber.
(b) End view of a sheath with three fibers.
A typical ADSL equipment configuration.
Passive optical network for Fiber To The Home.
(a) A binary signal
(b) Amplitude modulation
(c) Frequency modulation
(d) Phase modulation
TQ 6. The waveform of following figure belongs to a Manchester encoded binary data stream. Determine the beginning and end of bit periods (i.e., extract clock information) and give the data sequence.
Alternate Mark Inversion (AMI): 1s are represented by alternating positive and negative voltages.
In mBnL schemes, a pattern of m data elements is encoded as a pattern of n signal elements in which 2m ≤ Ln.