Module 4 - Cable Testing

wave

A ____ is energy traveling from point to point

electromagnetic spectrum

Voltage waves on copper media (light waves in optical fiber) use alternating electric and magnetic fields called the ______

height, volts

Wave, or signal amplitude, represents ____ and is measured in _____

Wave period, seconds

_____ is the amount of time to complete one cycle (past a given point) and measured in _____

Wave frequency, Hertz

_____ is the number of complete cycles per second, measured in _____

pulse

If a disturbance is caused, and involves a fixed, predictable duration, then it is called a ____.

Pulses

____ determine the value of the data being transmitted

Sine waves

_____ are mathematical functions with certain characteristics

Sine waves

_____ are periodic, (repeat the same pattern at regular intervals) and continuously varying (no two adjacent points have the same value).

Sine waves

They are graphical representations of natural occurrences changing over time

Square waves

_____ are periodic, however do not vary with time

Square waves

They hold a value for some time, then suddenly changes to a different value. They represent digital signals, or pulses

oscilloscope

An _____ is an electronic device used to view electrical signals, such as voltage waves and pulses

time, voltage or current

The horizontal (x-axis) shows ___, and the vertical (y-axis) shows ______

y-axis

There are usually two ____ inputs, so two waves can be observed and measured at the same time

time- domain analysis

Analyzing signals using the oscilloscope is called ______ because the x- axis represents time

Noise

____ usually refers to undesirable sounds

white noise

Noise affecting all transmission frequencies is called _____

narrowband interference

Noise affecting only a small range of narrowband frequencies is called ______

analog, digital

Two ways of considering bandwidth important to LANs is ____ and ____ bandwidth

Analog bandwidth, Hertz

______ describes the frequencies transmitted by a radio station or electronic amplifier. The unit of measurement is ____

Digital bandwidth, bits per second

_____ measures how much information can flow from one place to another in a given amount of time. The unit of measurement is _____

Attenuation

____ is the decrease in signal amplitude over the length of a link

decibels (dB), negative

Attenuation on a cable is measured in ____, using _____ numbers.

Impedance, ohms

____ is the measurement of resistance of the cable to alternating current (AC), and measured in ____.

impedance mismatch

If a connector is improperly installed on a cable, it has a different impedance value than the cable, which is called _____

insertion loss

The combination of the effects of signal attenuation and impedance mismatch on a communications link is called _____

Noise

_____ is electrical energy on the cable making it difficult for a receiver to interpret the data from the transmitter

Crosstalk

_____ involves the transmission of signals from one wire to a nearby wire

Cable testers

_____ measure crosstalk by applying a test signal on one wire pair.

NEXT (Near-end Crosstalk)

computed as the ratio of voltage amplitude between the test signal and the crosstalk signal when measured from the same end

FEXT (Far-end Crosstalk)

crosstalk occurring further away from the transmitter, creating less noise on the cable as NEXT

PSNEXT (Power Sum NEXT)

measures the cumulative effect of NEXT from all wire pairs in the cable

PSNEXT

____ is computed for each wire pair based on the NEXT effects of the other three wire pairs

Ethernet standards

______ specify each of the pins on the RJ- 45 connector have a specific purpose

1, 2, 3, 6

A NIC transmits on pins __ and __, and receives on pins __ and __

Wire map tests

____ ensure no open or short circuits exist on the cable

8

Wire map tests also ensure all __ wires are connected to the correct pins on both ends of the cable

Insertion loss

_____ is measured in decibels at the far end of the cable

four

Crosstalk is measured in ___ separate tests

cable tester

A ____ measures NEXT by applying a test signal on one cable pair and measuring the amplitude of the crosstalk received by the other cable pairs

ELFEXT

____ measures FEXT, and is expressed in decibels as the difference between the measured FEXT and the insertion loss of the wire pair whose signal is disturbed by the FEXT

Return loss

____ is a measure, in decibels, of reflections that are caused by impedance mismatches at all locations along the link.

jitter

The main problem is that the signal echoes caused by the reflections from the impedance mismatches will strike the receiver at different time intervals causing ____

optical fiber

Because noise is not an issue with ____, the main concern on the fiber link is the strength of the light signal that arrives at the receiver

optical link loss budget

The acceptable amount of signal power loss that can occur without dropping below the requirements of the receiver is called the _____

June 20, 2002

On _____, the CAT-6 addition to the TIA-568 standard was published

ten

Cables certified as CAT-6 must pass all ___ tests as those for CAT-5

Fluke DSP 4000, Fluke OMNIScanner 2

A quality cable tester similar to the ____ series or ______ can perform all the test measurements for CAT-5, CAT-5e, and CAT-6

data errors

If attenuation weakens the light signal at the receiver, then _____ will result