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The Physical Layer

Our goals: Transmission media: Magnetic media Twisted Pair(TP): UTP (unshielded), STP(shielded) Coaxial cable (Baseband/digital, Broadband/analogy) Optical Fiber (Single mode, multimode: graded-index, step-index) Satellite/Wireless (Microwave, Radio) Modulation technologies:

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The Physical Layer

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  1. Our goals: Transmission media: Magnetic media Twisted Pair(TP): UTP (unshielded), STP(shielded) Coaxial cable (Baseband/digital, Broadband/analogy) Optical Fiber (Single mode, multimode: graded-index, step-index) Satellite/Wireless (Microwave, Radio) Modulation technologies: Analogy: FM,AM,PM,… Digital: ASK, FSK, PSK, QPSK, QAM,… Digital Signal Encoding: RZ, NRZ, Manchester, 4B/5B,.. Digital Hierarchy: PDH, SDH, T1, E1,… The Physical Layer Physical Layer

  2. With better stability Transmission distance: 100m (without repeater) Connector: RJ-45(Internet), RJ-11 (phone) 10Baase-T, 100Base-T, 1000Base-T(Ethernet) Categories: Twisted Pair Physical Layer

  3. Twisted Pair: UTP & STP Physical Layer

  4. Immune to magneticwave interference RG-58 Broadband Coaxial Cable: impedance 75, analogy transmission, higher bandwidth Baseband Coaxial Cable: impedance 50, digital transmission, lower bandwidth T-type BNC connector Used by 10Base2 (Thin Ethernet), 10Base5 (Thick Ethernet) Coaxial Cabel Physical Layer

  5. Advantages: Immune to inference Long transmission distance High security High bandwidth, > 1 Gbps High stability Low loss Single Mode Fiber: LX SC connector Laser emitting, longer transmission distance Multimode Fiber: LED emitting, with dispersion, shorter transmission distance Step-Index Graded-Index Optical Fiber Physical Layer

  6. Optical Fiber Physical Layer

  7. A large repeater GEO：Geostationary Earth Orbit(~36000km) MEO：Medium-Earth Orbit LEO：Low-Earth Orbit Large coverage High economic efficiency Everywhere can see the sky can communicate Satellite Physical Layer

  8. Data Communication System Physical Layer

  9. Analogy Modulation AM (Amplitude Modulation): FM (Frequency Modulation): where PM (Phase Modulation) : Digital Modulation ASK, FSK, PSK, BPSK, QPSK QAM Modulation Technologies Physical Layer

  10. Digitize Technology:PCM Sampling: Nyquist Theorem Voice: 8kHz sampling rate Physical Layer

  11. PCM:Quantization Physical Layer

  12. Computation of Digital Data Volume What data volume of a song in the audio CD? Physical Layer

  13. 1 0 1 0 0 0 1 1 0 1 NRZ RZ Manchester Differential Manchester Bipolar Digital Signal Encoding Physical Layer

  14. Digital Hierarchy:PDH • PDH (Plesiochronous Digital Hierarchy) • Northern American Standards: T1(DS1), T2(DS2), T3(DS3), … DS1: Physical Layer

  15. Digital Hierarchy:PDH • PDH (Plesiochronous Digital Hierarchy) • European Standards: E1, E2, E3, … E1: Physical Layer

  16. Digital Hierarchy:SDH 0 0 Physical Layer

  17. Digital Hierarchy:SDH STS-1 (Synchronous Transport Signal-1) STM-1 (Synchronous Transfer Mode-1) SPE (Synchronous Payload Envelope) SONET Frame Format: Physical Layer

  18. Digital Hierarchy:SDH SDH Frame Format: Physical Layer

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