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Broadband Vs. Baseband Signals

  1. Jun 18, 2012 #1
    Hello everyone, a bit confused here and hoping for some clarification...

    I'm studying computer science, and in most of the books I've been reading most ethernet networks are baseband networks.. 10BaseT 100baseT...100baseFX..1000baseLX etc... Meaning only 1 signal can traverse the ethernet cat cable... The reason why dial up connection interrupted phone calls, because it used up the signaling for internet connection.
    Now here at school we have internet and printing done on 1 ethernet cable. My question is, how can the ethernet cable support both signals, the internet and the printing requests on 1 wire? I can send out printing requests, and surf the internet at the same time? How can I do this if our connection is based on a baseband technology? Or is it broadband and I just don't know? Like I said from my readings, they haven't discussed any broadband ethernet connections
  2. jcsd
  3. Jun 18, 2012 #2
    It does peices of one followed by peices of the other in little chunks called packets. It only appears as if it sends two things at once down the same cable.
  4. Jun 19, 2012 #3


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    There is a whole extra level involved.
    The (baseband) signals carried on ethernet cables are used to modulate a carrier on broadband systems or dial-up systems. In a dial-up, there is modulation of a low frequency carrier and the data signal overlaps the audio bandwidth. So you can only have one at a time. For a broadband system, the audio and data signals occupy different bands so they can co-exist. There are various ways of doing this but they all carry the 'broadband' signal at a frequency above the basic audio base band signal. I have Virgin cable and the up and down link signals in fact use different modulation systems and different data rates (according to the web page that the cable modem shows me on ADSL (the majority) uses a different arrangement. But all broadband systems use modulated carriers to achieve what they want.
  5. Jun 19, 2012 #4


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    The ethernet LAN is baseband. All machines on the network have a NIC ( Network Interface Card ) with a unique number. And any card that wants to transmit first checks if the line has no traffic and will then transmit. If not it waits, and tests the line again. The transmitting card sends some protocols of which include the address of the receiving machine and only that machine can accept the transmission. Other cards on the line can listen but not accept.
    Nowadays most LANS use a Switch. The switch has a list of all members on the line and traffic that comes into the switch is checked against the list and then sent out to the designated member.
    You might also want to look up routers, gateways, hubs, modems.
    Modems nowadays are not the old can only do one thing at a time one connection 56k type but highspeed data.
    In fact with the correct modem, you can surf the internet and watch TV at the same time and then through your LAN, printout a document and send a fax. Everything seems to happen all at the same time but really isn't.

    Transmission on the LAN is by what Antiphon stated.

    Communication to the outside world ( internet ) is through a modem and described by sophiecentaur.

    Here is a little site
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