Transcript Vector Network Analyzer

DCN286 INTRODUCTION TO DATA
COMMUNICATION TECHNOLOGY
Network Cable Testers and Tests
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.
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)
Sine wave
- Periodic
- Continuously
varying
- T = 1/F (T: period;
F: frequency)
Square wave
- Periodic
- NOT continuously
varying
- T = 1/F (T: period; F:
frequency)
Other waves (Optional)
• Triangle
• Sawtooth
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.
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.
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.
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.
Coaxial cable
• Shield must be
grounded.
• Plastic jacket can
offer protection
against moisture
and insulation.
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.
STP - 3 insulations
• Total 3 insulations:
1.Each thin wire is covered
in color-coded plastic
insulation
2.Each pair of wires is
twisted with a insulator
called a pair shield around
them
3.All the wires in the cable
(usually 4 pairs) are
covered by a shield called
the overall shield.
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)
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).
Ethernet Extender (optional)
Three primary purposes:
• Extend network coverage;
• Maintain the bandwidth;
• Control budget or TOC (Total Owner Cost)
TIA/EIA568-A and B pin outs
Pin #
1
2
3
4
5
6
7
8
Function
TD+
TDRD+
Unused
Unused
RDUnused
Unused
568A wire color
White/Green
Green
White/Orange
Blue
White/Blue
Orange
White/Brown
Brown
568 B wire color
White/Orange
Orange
White/Green
Blue
White/Blue
Green
White/Brown
Brown
Cable Specifications
Coaxial Cable
Shielded Twisted-Pair Cable
Unshielded Twisted Pair (UTP)
Unshielded Twisted Pair (UTP)
Unshielded Twisted Pair (UTP)
Straight Through Cable
Unshielded Twisted Pair (UTP)
Cross-Over Cable
Unshielded Twisted Pair (UTP)
Roll-over Cable
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.
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.
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.
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
PSNEXT (Power sum
Near-end Crosstalk)
• PSNEXT is to add all
pairs’ NEXT together.
• Becomes a part of
TIA/EIA 568B tests.
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
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.
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
Some basic cable testers
PatchTest Ethernet Cable Tester
Other Ethernet cable tester
• Connect cable
between receiver
and transmitter.
• Push button
sending test signals
Time Domain
Reflectometer
Tone tester (optional)
• Such tester can
be used to
identify
termination point
of wires or to
trace their paths
Test telephone (optional)
• Easy to be used to
verify phone line
connection
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)
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.ht
ml)
Bandwidth Monitor
(http://www.supershareware.com/info/bandwidthmonitor.html)
Real Time NetFlow Analyer
(http://www.solarwinds.com/products/freetools/netflow_analyz
er.aspx)
Network monitor (optional)
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
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  Ultraviolet  X Rays  Gamma Rays
In the line, wave length is reducing and frequency
is increasing.
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
Optic fiber cable testers
• SimpliFiber
Optical Loss Test
kits
• Fiber Optic
Cleaning Kits
• FiberViewer
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
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.
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
Introduction of Wireless Testers
(optional)
• Real Time Spectrum Analyzer
• RF environment scanner
Question
Any question?
If you do not have
question, please search
internet and collect more
information of those
cables testers and test
standards.
1. Please be comfortable to
list the pin wire colors.
2. Please be familiar with
those testing concepts.