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Session 9

Session 9. Data Communications and Cable Communications . Session Objectives. Midterm Returned Review, Session 8 - Network Services Data communications Cable communications High-definition television formats. Review, Session 8. How does a virtual network differ from a private network?

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Session 9

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  1. Session 9 Data Communications and Cable Communications Session 9 - Data and Cable Communications

  2. Session Objectives • Midterm Returned • Review, Session 8 - Network Services • Data communications • Cable communications • High-definition television formats Session 9 - Data and Cable Communications

  3. Review, Session 8 • How does a virtual network differ from a private network? • Compare DSL with ISDN as to information rate, flexibility, cost, and current availability. • How many links are required for an n-node star network? For an n-node full mesh? What does the result imply as to cost and reliability? • Explain how Common Channel Interoffice Signaling provides performance and cost gains. Session 9 - Data and Cable Communications

  4. Review for Session 8 (cont.) • Identify some of the subscriber services that SS7 makes possible. • Briefly explain “voice and data convergence” and its significance for telecommunications performance and cost. • What are advantages and disadvantages of ATM’s fixed, 53-byte cell size? Session 9 - Data and Cable Communications

  5. Data Circuit-Termination Equipment (DCE) • Terminates a network data circuit and interfaces with data terminal equipment (DTE) • Examples • Modem (plain, FAX, PCMCIA) • NT1 (for ISDN) • Channel Service Unit/Data Service Unit • Cable modems Session 9 - Data and Cable Communications

  6. DCE Functions • Analog-digital conversion • Maintaining required voltage levels • Synch • Error detection • Buffering • Compression • Testing point for network Session 9 - Data and Cable Communications

  7. Hybrid Fiber-Coax Architecture Session 9 - Data and Cable Communications

  8. Cable Modems • High interest; cf. AT&T-TCI merger • No standard yet • Functions • Interface to upstream and downstream channels • Analog-digital conversion, as before • Modulation of cable RF carrier with encoded data (as contrasted with baseband transmission of the data) • Demodulation of cable RF carrier to recover data • Filter packet addresses Session 9 - Data and Cable Communications

  9. Cable Pro’s Broadband Entertainment content Cable Con’s Small region coverage No switching experience Poor reliability Limited billing systems Meager R&D Scarce cash Poor reputation Telephone Con’s Narrowband No content origination Telephone Pro’s Large region coverage Switching competence Reliability Great billing experience Massive R&D Deep pockets Brand name recognition Large customer base Cable vs. Telephone Session 9 - Data and Cable Communications

  10. Title VI--Cable Communications • Sec. 601. Purposes • Establish franchise standards • Establish regulation guidelines • Establish protection for franchise renewal • Assure diversity • Promote competition • Sec. 611. May require channels for public, educational, and government (PEG) use Session 9 - Data and Cable Communications

  11. Title VI--Cable Communications (cont.) • Sec. 612. Must provide some channels for competitive commercial use • Sec. 613. Media cross-ownership allowed • Sec. 614. “Must carry” at least some local stations • Under election of right to carriage (Sec. 325.), or • Station’s “retransmission consent” (implies payment) • Sec. 615. Must carry noncommercial educational television Session 9 - Data and Cable Communications

  12. Title VI--Cable Communications (cont.) • Sec. 621. No exclusive franchises • Sec. 623. No regulation where effective competition exists; otherwise, regulates “basic tier” and unreasonable rates • Sec. 624A. TV, VCR, and cable compatibility • Sec. 629. Set-top boxes competitively available • Sec. 639. No obscene programming • Sec. 641. Scramble adult videos Session 9 - Data and Cable Communications

  13. Video Provisions (1996 Act) • Sec. 651. Video programming • As common carrier, or • As a cable system, or • As open video system • Sec. 652. No cable or telephone buy outs above 10% • Sec. 653. Open video systems • No discrimination • No hogging the system • Sec. 302 (1996 Act). No new video dialtone Session 9 - Data and Cable Communications

  14. Digital TV and Analog TV Comparisons • Analog TV Characteristics • 6 MHz analog signal carries intensity and color info • 525 scan lines by 500 pixels per line (262,500 pixels) • 1/60 sec. Interlaced (refreshed image every 1/30 sec.) • Digital TV (DTV) Characteristics • 6 MHz compressed digital signal carries increased detail and high quality Dolby Digital Surround sound • 720 scan lines by 1080 pixels (777,600 pixels) • 1/60 sec. Interlaced and Progressive Frame Rates Session 9 - Data and Cable Communications

  15. HDTV Video Graphics Array (VGA) Formats • Formats Used in HDTV • 480i = 640x480 pixels interlaced • 480p = 640x480 pixels progressive • 720p = 1280x720 pixels progressive • 1080i = 1920x1080 pixels interlaced • Scanning System Formats • Interlaced Format, 1/60 sec. (1/30 sec. image refresh) • Progressive Format, 1/60 sec. whole image refresh • Interlaced has flicker and Progressive uses bandwidth Session 9 - Data and Cable Communications

  16. Digital TV Scanning Formats Session 9 - Data and Cable Communications

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