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  • Communications not direct, but via a signal Signal goes thru a communications medium which is anything that can carry the signal between the sender and the receiver
  • Telecommunications - electronic transmission and reception of communication signals. Data communications - electronic transmission and reception if digital data, usually between computer systems Telecommunications network - connects communications and computing devices Computer Network - connects computers and computer systems for data communications
  • Media - anything that will carry a signal and creates an interface btwn sender and receiver Devices - Hardware device that enables or controls communication signals Software - computer program that enables or controls communication signals
  • Analog - wave Digital discreet - high or low Transmission speed - how fast the frequency (change from high to low Band width - how many bits per second
  • Media - what the signal travels on - Some media do voice, some do data, some do both Each media has its own characteristics Cable - have to attach devices physically. Wireless - devices must be close enough to receive signals
  • Twisted pair - Pairs of twisted wire w/in an insulated layer. Used for phone line Most popular Cat1, cat 2 - 1 Mbps for voice cat 5 private computer networks 100 Mbps for data cat 7 high traffic 10 Gbps Coax - cable TV - inner conductive wire surrouded by insulation With development of cat 5, not used too much for networks Fiber optic - thousands of strands of glass or plastic in sheathing 1.6 to 10 Tbps Very thin, good signal Very secure, light rather than Electical pulse Very expensive
  • Signal travels thru air - need antennea to receive it FCC regulates what frequency can be used for what broadcasts AM radio lower than FM Measured in Hertz, K and M High speed (frequency) microwaves Infrared is a higher frequency, just below visible light
  • Devices send and receive signals Basic catagories of Network Devices - modems, network adaptors, control devices Computers connect to networks and Internet via a modem, a network adaptor or a combination of both Control Devices control the flow of bits within a network - insure signal reaches its destination
  • Modem stands for modualtion/demodulation - used to convert analog signal to digital and vise versa. Used to convert analogue phone line to digital. Used to connect computer to Net (though it can be used to connect to other networks) Standard on today’s PC’s Can be internal of external Special modems used to connect to highspeed networks. Cable modem - connect to internet over cable TV lines DSL - Direct Subscriber Line - Hi-speed net connection availble from the phone company
  • NIC Circuit board plugged into mother board, or PC card (notebook), or USB device that allows a computer to connect to network Wireless adaptors also circuit board, pc card or usb device provides an external antenna to connect send and receive network signals
  • Hub - central point to connect a group of computers - signal from one machine broadcast to all of the other machines connected to the hub - party line Switches- Connects pairs of machines together as needed - regular phone line Repeaters - connect multiple netwoek segments - listening for a signal on one segment and repeating it on all other segments connected to repeater Bridges - repeats but also helps regulate flow of signals
  • Gateway - network point that acts as an entrance to another gateway - translate from on protocol to another Router - Connects different networks, creates logical subnetworks, will not allow a signal to go where it shouldn’t Wireless access points - Allow wireless devices to connect to a network - broadcasts network signals to machines equipted w/ an antenna Firewall - hardware or software that filters the signals coming into a network - protects the network
  • Lecture7.ppt

    1. 1. Networking Telecommunications, Wireless Technologies, and Computer Networks
    2. 2. Communications Transmission of a signal between a sender and a receiver by way of a medium
    3. 3. Telecommunications <ul><li>Electronic transmission and reception of signals </li></ul><ul><li>Three types of telecommunications </li></ul><ul><ul><li>Data communications </li></ul></ul><ul><ul><li>Telecommunications network </li></ul></ul><ul><ul><li>Computer network </li></ul></ul>
    4. 4. Telecommunications Components <ul><li>Networking media </li></ul><ul><li>Networking devices </li></ul><ul><li>Network software </li></ul>
    5. 5. Telecommunications Signals <ul><li>Types of signals </li></ul><ul><ul><li>Analog </li></ul></ul><ul><ul><li>Digital </li></ul></ul><ul><li>Transmissions speed </li></ul><ul><li>Bandwidth </li></ul><ul><ul><li>Broadband - 3 Mbps to 6 Mbps </li></ul></ul><ul><ul><li>Narrowband - 56 Kbps to 200 Kbps </li></ul></ul>
    6. 6. Networking Media <ul><li>Cables </li></ul><ul><ul><li>Twisted pair </li></ul></ul><ul><ul><li>Coaxial </li></ul></ul><ul><ul><li>Fiber optic </li></ul></ul><ul><li>Wireless </li></ul><ul><ul><li>Radio waves </li></ul></ul><ul><ul><li>Infrared light </li></ul></ul>
    7. 7. Cables <ul><li>Twisted pair </li></ul><ul><ul><li>Phone line </li></ul></ul><ul><ul><li>Cat 1 to Cat 7 </li></ul></ul><ul><li>Coaxial </li></ul><ul><ul><li>Cable TV </li></ul></ul><ul><li>Fiber Optic </li></ul>
    8. 8. Wireless Signals <ul><li>Radio Waves </li></ul><ul><ul><li>Electromagnetic </li></ul></ul><ul><ul><li>Varying Frequencies </li></ul></ul><ul><li>Infrared Light </li></ul><ul><ul><li>Light Waves </li></ul></ul><ul><ul><ul><li>Longer than visible light </li></ul></ul></ul><ul><ul><ul><li>Shorter than radio waves </li></ul></ul></ul>
    9. 9. Networking Devices <ul><li>Modems </li></ul><ul><li>Network Adaptor </li></ul><ul><li>Network Control Devices </li></ul>
    10. 10. Modem <ul><li>Modulation/Demodulation </li></ul><ul><li>Cable Modem </li></ul><ul><li>DSL Modem </li></ul>
    11. 11. Network Adapters <ul><li>Network Interface Card (NIC) </li></ul><ul><li>Wireless Adapters </li></ul>
    12. 12. Network Control Devices <ul><li>Hubs </li></ul><ul><li>Switches </li></ul><ul><li>Repeaters </li></ul><ul><li>Bridges </li></ul>
    13. 13. More Network Control Devices <ul><li>Gateways </li></ul><ul><li>Routers </li></ul><ul><li>Wireless Access Points </li></ul><ul><li>Firewalls </li></ul>
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