Lecture Notes: Session 3/CS461

"Basics of Transmission Systems, Cont., Analog vs. Digital, Carrier Services"




  1. Review:
    1. Diagram the local loop.
    2. Discuss one regulatory change and one technical change that occurred as a result of the Modified Final Judgment of 1984.
    3. List the four types of encoding that can occur in the conceptual communications model and give examples of each.
    4. Outline the conceptual telecommunications model.
    5. Explain the difference between time division multiplexing and frequency division multiplexing
  2. Receiving=>process of capturing an encoded signal and relaying it to the decoding device.
    1. Collecting=>process of capturing an electromagnetic wave from a transmitting antenna.
    2. Connecting=>moving signals through a channel to the decoding process or device.
    3. Amplifying=>same as on the transmission end
    4. Demodulating=>reverse of modulating, but with all the same subconcepts
  3. Storing=>saving information (signals) for later use.
    1. Paper
    2. Film
    3. Magnetic Media
      1. Benefits
      2. Disadvantages
    4. Optical Disks
  4. Retrieving=>process of accessing stored information
    1. Abstracting=>process of identifying the content of stored information
    2. Indexing=>process of coding an item (name) for later retrieval
    3. Accessing=>process of locating a stored item by using the abstract and index
    4. Controlling=>determining who has access to specific information (also called authentication control)
    5. Decoding=>process of presenting information in a usable format.
  5. Analog vs. Digital Transmission
    1. Analog Transmission (review)
      1. Amplitude (volume)
      2. Frequency (pitch)
    2. Amplifiers
    3. Analog to Digital Conversion
      1. Nyquist Theorem =>sample signal at twice the maximum frequency of the line
        1. 4kHz line = 8000 samples per second
        2. Byte representation
        3. 8000 samples per second x 8 bits per byte=64,000 bps or Digital Services zero (DS0).
      2. Repeaters/Regenerators
    4. Digital Signalling
      1. Binary representation in voltage
      2. Serial communication
      3. Why bother with digital conversion?
  6. Modems
  7. Dial-up modem pool evolution
  8. Dial-up networking
    1. DePaul Online network; view 1
    2. Current DPO network
  9. Local Exchange Carrier (LEC) Services
    1. Local Dial Tone and Party Line Service
      1. Dial Tone (line access)=>
      2. Party Lines=>
    2. Centrex Services

    4. Business Service
      1. Direct Inward Dial=>
      2. Direct Outward Dial=>
    5. Residential Services
      1. Flat-rate vs. measured service=>
    6. Local Calling Services (DDD)=>
    7. Pay Phone Services=>
      1. Public Pay Phone=> Semipublic Pay Phone=>
      2. Private Pay Phone=>
    8. Private Lines and Tie Lines
    9. Foreign Exchange (FX) Services
      1. Leased-line service that allows a customer to draw dial tone from a remote central office in the LEC's service area.
    10. WATS, IN-WATS, 500-Service, and 900 Service
      1. WATS=>Wide-area telecommunications services; Refers to outbound calls only, not inbound.
        1. old style with banded service rates
        2. Full-time WATS=>
        3. Measured WATS=>
      2. LEC-Intrastate WATS=>
      3. One-Plus WATS=>
      4. 800-Service=>
      5. Directory Services=>
      6. Off-Premises Extensions=>OPX;
    11. Old DePaul Voice Network
  10. Access to Interexchange Carriers (Equal Access)
  11. InterExchange (IEC/IXC) Carriers
    1. Switched Long Distance (DDD)
    2. Credit Card Service
    3. WATS Service
    4. 800-900 Service Offerings
    5. International (IDDD) Access
    6. Foreign Exchange Service (FX)
    7. Off Preises Extensions (OPX)
    8. Operator/Directory Assistance
    9. Remote Call Forwarding
    10. Value-Added Carriers
    11. Alternate Operator Services (AOS)
    12. Aggregators
    13. Competitive Access Providers (CAPs)
    14. Resellers