DCN286 INTRODUCTION TO DATA COMMUNICATION TECHNOLOGY

1
DCN286 INTRODUCTION TO DATA COMMUNICATION
TECHNOLOGY

• Network Cable Testers and Tests

2
Digital Signal Transmission

1. By varying an electrical signal when it passes
   over a wire that is typically made of copper.
2. By varying the power of light as sent over a
   glass optical fiber.
3. By varying the radio waves sent through space,
   which is commonly referred to as wireless
   communications.

3
Common terminologies in waves

• Amplitude height of wave (volt, meter, amp, etc,
  etc) which usually means strength of waves.
• Frequency number of waves per second
  (hertz1/second). High frequency means more waves
  coming in one second.
• Period time between each waves. Higher period
  also means lower frequency (less waves coming in
  each second)

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Sine wave

• Periodic
• Continuously varying
• T 1/F (T period F frequency)

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Square wave

• Periodic
• NOT continuously varying
• T 1/F (T period F frequency)

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Other waves (Optional)

• Triangle

• Sawtooth

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Analog and digital wave

• Analog wave usually refers to sine wave as it
  can easily presents many natural events.
• Digital wave usually associated with square wave
  because it presents binary digits.

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Combined waves

• Frequency of wave 1 is 300 hz
• Frequency of wave 2 is 500 hz
• When they are added together, blue wave presents
  the complex combined wave.

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Signals and Noise

• Signal the desired binary digits presented by
  the energy (electric, light and radio)
  transmission.
• Noise any environmental interference while
  receiver detects the data signal.
• Other factors might degrade signals grade of the
  cable, connector and installation (connection),
  distance of cable connection and network design.

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Impedance and attenuation

• Impedance contains the material resistance and
  other resistant forces in a circuit.
• Attenuation- the amount of signals that a cable
  will absorb is a measure of its attenuation.
  Lower attenuation indicates higher quality
  conductors and cables.
• Voltage (electrical power) and light power would
  decrease while travelling alone copper wires and
  optic fiber cables.

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Coaxial cable

• Shield must be grounded.
• Plastic jacket can offer protection against
  moisture and insulation.

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STP (Shielded Twisted Pair) cable

• Shielding provides better electrical signals by
  reducing noise and attenuation.
• Shielding makes the cable more expensive, heavier
  and hard to bend.

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STP - 3 insulations

• Total 3 insulations
• Each thin wire is covered in color-coded plastic
  insulation
• Each pair of wires is twisted with a insulator
  called a pair shield around them
• All the wires in the cable (usually 4 pairs) are
  covered by a shield called the overall shield.

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Single bit

• In a 100Mbps cable transmission, how long will a
  bit be sent/received?
• 1/100,000,000 of 1 second
• (100,000,000b 100Mb)

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UTP (Unshielded Twisted Pair)

• Twist offers the resistance to interference!!!
• Flexible and easy install
• Offer the same data speeds
• Inexpensive
• RJ45 connector (RJ11 is for phone cable).

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Ethernet Extender (optional)

• Three primary purposes
• Extend network coverage
• Maintain the bandwidth
• Control budget or TOC (Total Owner Cost)

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TIA/EIA568-A and B pin outs
Pin Function 568A wire color 568 B wire color
1 TD White/Green White/Orange
2 TD- Green Orange
3 RD White/Orange White/Green
4 Unused Blue Blue
5 Unused White/Blue White/Blue
6 RD- Orange Green
7 Unused White/Brown White/Brown
8 Unused Brown Brown
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Cable Specifications
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Coaxial Cable
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Shielded Twisted-Pair Cable
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Unshielded Twisted Pair (UTP)
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Unshielded Twisted Pair (UTP)
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Unshielded Twisted Pair (UTP)
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Straight Through Cable
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Unshielded Twisted Pair (UTP)
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Cross-Over Cable
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Unshielded Twisted Pair (UTP)
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Roll-over Cable
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How to maintain quality

• Well network design (will be taught later)
• Certified technician who usually has better
  installation knowledge
• Certified cables (better quality connectors and
  cables)
• Well insulation (new cable usually does not have
  broken insulation ? )
• Environment check and tests.

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Crosstalk

• When current flows over a nearby wire, it
  generate EMI and cause crosstalk.
• Near-end crosstalk (NEXT)
• Far end crosstalk (FEXT)
• Power sum near-end crosstalk (PSNEXT)
• How to read NEXT?
• NEXT is expressed as a negative value of
  decibels. -30dB means less NEXT.

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NEXT (Near-end crosstalk)

• It occurs near the source of the test signal
• NEXT current direction is opposite to the
  transmitted test signal direction
• Test signal and NEXT test are on same side of the
  connection.

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FEXT (Far End Crosstalk)

• Used to test crosstalk in the same circumstances
  of NEXT
• The only difference to NEXT is to detect a signal
  crossing (disruption) that is located at a
  distance from the point of measurement.
• FEXT may cause less noise than NEXT

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PSNEXT (Power sum Near-end Crosstalk)

• PSNEXT is to add all pairs NEXT together.
• Becomes a part of TIA/EIA 568B tests.

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Standard Tests for Cable certification

• Wire map Identify physical error of any
  miss-wiring
• Insertion loss Lose of signal strength,
  expressed in dB.
• NEXT A higher value is desirable, meaning better
  cable performance
• PSNEXT Combined NEXT
• Equal-level Far-end Crosstalk (ELFEXT) FEXT is
  usually less detrimental to a signal than NEXT
• Power sum equal-level far-end crosstalk
  (PSELFEXT) sum of all FEXT
• Return loss measured in dB and indication of bad
  crimp or bad connection at the RJ45 plug.
• Propagation delay tests for the time it takes
  for the signal to be sent from one end and
  received by the other end
• Cable length Verify not exceed 100m. Also find
  shortcut or where the broken point is
• Delay skew Tests for difference between the
  fastest and slowest set of wire pairs. Lower is
  better. Could be between 25-50 nanoseconds over
  100m

35
Professional cable certification tester

• Fluke DTX CableAnalyzer

LT8000 Series Cable Certification Tester
Copper cable certification is achieved through a
thorough series of tests in accordance with
Telecommunications Industry Association (TIA) or
International Organization for Standardization
(ISO) standards.
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Testers

• Regular DC/AC voltmeters, Ammeters, and Ohmmeters
  (multimeter)
• Signal testers function generators, pulse
  generators, RF signal generators, sine wave
  sources, etc, etc.
• Oscilloscope and mixed signal probes
• Wave form measurements square wave test, Time
  Domain Reflectometer, Diode I-V characteristic,
• Electronic Counters frequency dividers, Period
  measurement, Reciprocal counter, Universal
  counter,
• Power supplies and remote sensing
• Spectrum and network analyzers
• Logic Analyzers Logic analyzer, timing analyzer,
  Mi

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Some basic cable testers
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PatchTest Ethernet Cable Tester
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Other Ethernet cable tester

• Connect cable between receiver and transmitter.
• Push button sending test signals

Time Domain Reflectometer
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Tone tester (optional)

• Such tester can be used to identify termination
  point of wires or to trace their paths

41
Test telephone (optional)

• Easy to be used to verify phone line connection

42
Online Internet Bandwidth Tests

• Many websites can be used to test internet upload
  and download speed
• www.speedtest.net
• www.bandwidthplace.com/
• www.speakeasy.net/speedtest
• http//reviews.cnet.com/internet-speed-test/
• www.toast.net
• http//promos.mcafee.com/speedometer/test_0600.asp
  (McAfee internet Connection Speedometer)

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LAN speed test

• Many free software programs are available
• Iperf bandwidth test (http//lss.rutgers.edu/index
  .php?pagetool_iperf)
• QCheck (http//www.ixchariot.com/products/datashee
  ts/qcheck.html)
• Bandwidth Monitor
• (http//www.supershareware.com/info/bandwidth-moni
  tor.html)
• Real Time NetFlow Analyer
• (http//www.solarwinds.com/products/freetools/netf
  low_analyzer.aspx)

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Network monitor (optional)
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Network Analyzer (optional)

• 1. Hardware equipment
• The two main categories of Network Analyzers are
• Scalar Network Analyzer (SNA) - Measures
  amplitude properties only
• Vector Network Analyzer (VNA) - Measures both
  amplitude and phase properties,
• 2. Software used for network analyzer
• Wireshark, Ethereal, CommView, Network Sniffer,
  Network Packet Analyzer, Distinct Network
  Monitor, etc, etc

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Use light energy

• Electrical signal use on (high voltage) and off
  (low voltage) to transmit 1 and 0 in copper
  cable.
• Light signal can also use on (brighter light) and
  off (dim light) to transmit 1 and 0 in
  fiber-optic cables.

EM spectrum
Audi ? Radio ? Microwaves ? Infrared ?
Ultra-violet ? X Rays ? Gamma Rays In the line,
wave length is reducing and frequency is
increasing.
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Optic media

• Fiber-optic cable has the strongest ability to
  resist EMI (electromagnetic interference), RFI
  (Radio Frequency Interference)
• Fibers bandwidth is much higher than any other
  media.
• Fiber is highly secure and it is easy to detect
  intrusion.
• Fiber uses light signal transmission and its
  attenuation is much less than electrical signals.
  Its length could be very long

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Optic fiber cable testers

• SimpliFiber Optical Loss Test kits

• Fiber Optic Cleaning Kits

• FiberViewer

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Optical fiber Test

• Certifies compliance of multimode fiber networks
  to industry standards. Can test two fibers at two
  wavelengths simultaneously with one-button
  Autotest

• The tester may have curve display
• Or, it has numeric output

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Wireless tech introduction

• Infrared
• Bluetooth
• Microwave
• Radio
• Wi-Fi
• In general, wireless network is secondary because
  of two concerns speed and security. But, it does
  offer mobility and convenience.

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Main wireless components

• Access point linking wireless network to the
  wired world.
• Wireless NIC on each hosts in the network
• Wireless hub, switch and router functioning as
  same as regular wire connected equipments

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Introduction of Wireless Testers (optional)

• Real Time Spectrum Analyzer

• RF environment scanner

53
Question

• Any question?
• If you do not have question, please search
  internet and collect more information of those
  cables testers and test standards.
• Please be comfortable to list the pin wire
  colors.
• Please be familiar with those testing concepts.