MindMap Gallery physical layer
Physical layer mind map, including an overview of the physical layer, Basic knowledge of data communication, transmission media, Channel multiplexing technology, etc.
Edited at 2024-04-02 20:37:46This Valentine's Day brand marketing handbook provides businesses with five practical models, covering everything from creating offline experiences to driving online engagement. Whether you're a shopping mall, restaurant, or online brand, you'll find a suitable strategy: each model includes clear objectives and industry-specific guidelines, helping brands transform traffic into real sales and lasting emotional connections during this romantic season.
This Valentine's Day map illustrates love through 30 romantic possibilities, from the vintage charm of "handwritten love letters" to the urban landscape of "rooftop sunsets," from the tactile experience of a "pottery workshop" to the leisurely moments of "wine tasting at a vineyard"—offering a unique sense of occasion for every couple. Whether it's cozy, experiential, or luxurious, love always finds the most fitting expression. May you all find the perfect atmosphere for your love story.
The ice hockey schedule for the Milano Cortina 2026 Winter Olympics, featuring preliminary rounds, quarterfinals, and medal matches for both men's and women's tournaments from February 5–22. All game times are listed in Eastern Standard Time (EST).
This Valentine's Day brand marketing handbook provides businesses with five practical models, covering everything from creating offline experiences to driving online engagement. Whether you're a shopping mall, restaurant, or online brand, you'll find a suitable strategy: each model includes clear objectives and industry-specific guidelines, helping brands transform traffic into real sales and lasting emotional connections during this romantic season.
This Valentine's Day map illustrates love through 30 romantic possibilities, from the vintage charm of "handwritten love letters" to the urban landscape of "rooftop sunsets," from the tactile experience of a "pottery workshop" to the leisurely moments of "wine tasting at a vineyard"—offering a unique sense of occasion for every couple. Whether it's cozy, experiential, or luxurious, love always finds the most fitting expression. May you all find the perfect atmosphere for your love story.
The ice hockey schedule for the Milano Cortina 2026 Winter Olympics, featuring preliminary rounds, quarterfinals, and medal matches for both men's and women's tournaments from February 5–22. All game times are listed in Eastern Standard Time (EST).
physical layer
Physical layer overview
characteristic
Mechanical properties
Electrical characteristics
Features
Procedure characteristics
four Q
Choice of physical transmission media
information encoding problem
Performance analysis (transmission speed)
Channel multiplexing
Basic knowledge of data communications
data and signals
Classification
Analog: Continuous
digital: discrete
data to signal
Analog data to analog signal (amplifier, modulator):
Analog data to digital signal (PCM encoder): sampling, quantization, encoding
Digital data to analog signal (modulator): can be through amplitude modulation, frequency modulation or phase modulation
Digital data to analog signal (digital transmitter)
non-return-to-zero encoding
1=-5V, 0=5V
Disadvantage: Transformer cannot be used during the process
Manchester encoding
1=low to high potential jump, 0=high to low potential jump
Disadvantage: The signal rate is twice the data rate (two potentials in one time interval)
Differential Manchester encoding
1=No transition, 0=There is a transition
Data communication system model
Communication Systems
Types of communication
According to the type of signal transmitted: analog, digital
According to transmission media: wired, wireless
According to the way of information exchange: simplex, half-duplex, duplex
Basic parameters of communication system performance
Data rate (bit rate)
Unit: bps
C (data rate) = B (baud rate) log₂V (voltage level)
Symbol rate (baud rate)
Unit: baud
Is the basic unit of the signal. The symbol for the signal is equal to the bit for the data.
Code element length: Use symbols with the same time interval to represent a number, so that the time interval
Code element: Use symbols with the same time interval to represent a number, so that the signals within the time interval
Channel capacity
Maximum data rate of the channel
signal-to-noise ratio
=S (signal power)/N (noise power)
Usually expressed in logarithmic form: 10lg (S/N)
Unit: 10lg (signal-to-noise ratio) dB
Signal-to-noise ratio 1000 is 30dB
Channel bandwidth
The frequency range that the channel can pass
low pass, band pass, high pass
limited bandwidth signal
Signal bandwidth: Any signal can be transformed into the sum of multiple sine waves through Fourier transform
Channel bandwidth
The ultimate capacity of the channel
Nye's criterion
The maximum symbol rate for a low-pass noiseless channel is equal to twice the channel bandwidth
The maximum symbol rate of a bandpass noiseless channel is equal to the channel bandwidth
Shannon's theorem: C=Wlog₂(1 S/N) bps
C: The limit information transmission rate of the channel, W: Bandwidth
Transmission medium
Wired (guided)
Twisted pair: UTP (unshielded), STP (shielded), RJ connector
coaxial cable
Optical cable: single-mode optical fiber, multi-mode optical fiber, electrical signal-optical signal
Magnetic media
power line
Wireless (non-guided)
Shortwave: reflection from the ionosphere
Terrestrial microwave: transmission in a straight line (large bowl)
Satellite Communications
infrared
Channel multiplexing technology
Signal time domain and frequency domain
FDM (Frequency Division Multiplexing)
TDM (Time Division Multiplexing)
STDM (statistical time division multiplexing)
WDM (Wavelength Division Multiplexing)
CDM (Code Division Multiplexing)