DCN286 INTRODUCTION TO DATA COMMUNICATION TECHNOLOGY

1. DCN286 INTRODUCTION TO DATA COMMUNICATION TECHNOLOGY Network Cable Testers and Tests

2. Digital Signal Transmission • By varying an electrical signal when it passes over a wire that is typically made of copper. • By varying the power of light as sent over a glass optical fiber. • 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 (hertz=1/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)

4. Sine wave • Periodic • Continuously varying • T = 1/F (T: period; F: frequency)

5. Square wave • Periodic • NOT continuously varying • T = 1/F (T: period; F: frequency)

6. Other waves (Optional) • Triangle • Sawtooth

7. 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.

8. 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.

9. 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.

10. 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.

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

12. 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.

13. 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.

14. 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)

15. 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).

16. Ethernet Extender (optional) Three primary purposes: • Extend network coverage; • Maintain the bandwidth; • Control budget or TOC (Total Owner Cost)

17. TIA/EIA568-A and B pin outs

18. Cable Specifications

19. Coaxial Cable

20. Shielded Twisted-Pair Cable

21. Unshielded Twisted Pair (UTP)

22. Unshielded Twisted Pair (UTP)

23. Unshielded Twisted Pair (UTP)

24. Straight Through Cable

25. Unshielded Twisted Pair (UTP)

26. Cross-Over Cable

27. Unshielded Twisted Pair (UTP)

28. Roll-over Cable

29. 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.

30. 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.

31. 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.

32. 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

33. PSNEXT (Power sum Near-end Crosstalk) • PSNEXT is to add all pairs’ NEXT together. • Becomes a part of TIA/EIA 568B tests.

34. 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.

36. 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

37. Some basic cable testers

38. PatchTest Ethernet Cable Tester

39. Other Ethernet cable tester • Connect cable between receiver and transmitter. • Push button sending test signals Time Domain Reflectometer

40. 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)

43. LAN speed test Many free software programs are available: Iperf bandwidth test (http://lss.rutgers.edu/index.php?page=tool_iperf) QCheck (http://www.ixchariot.com/products/datasheets/qcheck.html) Bandwidth Monitor (http://www.supershareware.com/info/bandwidth-monitor.html) Real Time NetFlow Analyer (http://www.solarwinds.com/products/freetools/netflow_analyzer.aspx)

44. Network monitor (optional)

45. 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

46. 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.

47. Optic media • Fiber-optic cable has the strongest ability to resist EMI (electromagnetic interference), RFI (Radio Frequency Interference) • Fiber’s 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

48. Optic fiber cable testers • SimpliFiber Optical Loss Test kits • Fiber Optic Cleaning Kits • FiberViewer

49. 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

50. 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.