Introduction to Wired Communications and Coaxial Cable

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Time
9 hours 49 minutes
Difficulty
Beginner
CEU/CPE
10
Video Transcription
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>> Our next section is on wired connections.
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Here we'll take a look at different types of media.
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I love the picture on the right because I swear to you,
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I've walked into rooms and seeing
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marine rocks just like this.
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It gives me a memory back to the olden days.
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For some media types,
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we'll talk about serial connections with RS232.
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That's an IEEE standard.
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We've also got twisted pair cabling
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and with twisted pair cabling,
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we have two flavors, shielded and unshielded.
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We've got coaxial cable and then of course,
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fiber optic cable where we
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have multimode and single mode.
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These aren't used that frequently today.
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These were used for cable modems back in the day.
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These connector types are either referred to
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as DB-9s, are DE-9s.
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They've been replaced by USB and don't be
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surprised if something dated shows up on the exam.
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It's always good to know where we've come from.
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That way we can know where we are.
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USB connections really have replaced this,
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but these were used for serial connections.
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Again, we saw them used a lot with modems.
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There are various cable types that we use today,
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we have coaxial,
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which is here on the left and
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underneath you've got connector types.
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You definitely want to be able to match
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the cable type to the connector.
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You can see the way coaxial cable is done,
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and you can see why it's called coaxial.
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We have two axes running with each other.
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Of course, this is copper-based cabling.
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It has some of the problems that
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copper-based cabling has,
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like it's easy to eavesdrop,
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it's susceptible to electromagnetic interference.
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Although coaxial is better than UTP twisted pair cabling,
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it's still has some susceptibility to interference.
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Back in the day when we used coaxial cable,
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we used it in an old bus networks
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where we had a central trunk of cable,
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which is what we referred to as thick net.
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Thick net cable had an attenuation length of 500 meters,
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so you could go a long distance with
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thick coaxial cable before you suffered an attenuation.
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Attenuation is the idea that the longer the cable,
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the weaker the signal until you really get to
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a point where signal isn't quality any longer.
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We use a thicknet as our trunk because of
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the fact that it did carry data so long.
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Then we sometimes use thin net
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as connections directly to the host.
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Thinnet had a distance of 185 meters,
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so a little shorter but fairly decent.
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We connect into the host with BNC connectors.
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We add F connectors, barrel connectors,
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and T connectors, all different connector types.
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This is what we're seeing with cable,
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cable TV and connectivity to the Internet through cable.
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You've probably seen coaxial before.
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Another type, I'm sure you've seen it
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before is twisted pair cabling.
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This is by far the most hatcom going back.
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This is by far
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the most common type of cabling and practice today,
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and you can see why it has the name twisted pair.
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You have eight individual wires
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and they are twisted together in pairs.
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The idea about the twist is when you have
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copper cabling running side-by-side,
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you can have an issue called signal bounds.
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Signal bounds where it jumps from one signal to the
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next or from one wire to the next back-and-forth.
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The twist actually prevent that.
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We also look at the idea that
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there is certain configurations
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for how these twists should be set
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up depending on the type of cable.
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We connect these wires into connector is called RJ45s.
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The RJ45 is going to look a lot like
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the RJ11 that we use for phone systems.
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The big difference is four wires
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are used for the phone system,
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and we use all eight for RJ45s.
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Also, twisted pair cabling is very
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susceptible to interference and cross-talk,
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and that's actually what it's called.
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When a signal jumps from one wire
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to another, it's called cross-talk.
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The twists can help alleviate that.
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What you'll find is twisted pair cabling won't
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give you the length that other type of cables will.
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They'll allow you about 100 meters
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before their attenuation sets.
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in The biggest reason that we use
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twisted pair cabling today is
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because it's cheap and easy to work with.
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It's significantly cheaper than
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any other types of cables.
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It's very flexible and it's not a rigid cable type.
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We want to keep that in mind that
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many times cheap makes the decision for us.
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Twisted pair cabling is very susceptible to
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radio frequency interference,
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electromagnetic interference.
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Again, only has
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a short distance of 100 meters before attenuation,
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but the money always wins.
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Our final illustration, we see fiber optic cable.
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Fiber optic cable is made of
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glass and the signal is sent through pulses of light.
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The big benefit in addition to speed,
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is it's very difficult to eavesdrop
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>> on fiber optic cable.
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>> Also, you don't have problems like EMI and RFI.
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You get great speed. You get
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great distance with fiber optic cable,
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but the downside is it's expensive.
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On the exam you will need to be
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able to name your connector types.
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I would pay particular attention here.
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If we look at the ST connector,
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you've got a bayonet type of connector
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where you can see the elements
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sticking out to make the connection.
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LC is a push-pull,
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LCs give you the clip on top.
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MTRJs also have that
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snapping connector in a much smaller form factor.
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When we say form factor,
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we usually mean physical design.
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Those are some of the common
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connector types for fiber optic.
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Make sure you know, RJ45 or twisted pair.
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Make sure you know, BNC connectors for coaxial.
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