Chapter 1 - Part 1 Flashcards
Amplitude
The maximum absolute value reached by a voltage or current waveform.
TDMM: PAGE G-9
Amplitude Modulation
(AM)
The modulation in which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal.
TDMM: PAGE G-9
Analog Signal
A signal in the form of a wave that uses continuous variations of a physical characteristic over time (e.g., voltage amplitude, frequency) to transmit information.
TDMM: PAGE G-9
Attenuation
The ratio in decibels of the output power (or voltage) to the input power (or voltage) when the load and source impedance are matched to the characteristic impedance of the cable.
TDMM PAGE 1-53
ATM
A HIGH-SPEED PACKET SWITCHING PROTOCOL THAT USES FIXED-LENGTH (53-BYTE) PACKETS ORGANIZED INTO CELLS TO CARRY ALL TYPES OF TRAFFIC (E.G., VOICE, DATA, STILL IMAGE, AUDIO/VIDEO). FIXED-LENGTH CELLS ALLOW CELL PROCESSING TO OCCUR IN THE HARDWARE, THEREBY REDUCING DELAYS. ATM IS DESIGNED TO TAKE ADVANTAGE OF HIGH-SPEED TRANSMISSION MEDIA, SUCH AS E3, SYNCHRONOUS OPTICAL NETWORK (SONET), AND T3.
TDMM: PAGE G-13
AWG
AMERICAN WIRE GUAGE
A SYSTEM USED TO SPECIFY WIRE SIZE. THE GREATER THE WIRE DIAMETER, THE SMALLER THE AWG VALUE.
TDMM: PAGE G-8
BANDWIDTH
A RANGE OF FREQUENCIES AVAILABLE FOR SIGNALING EXPRESSED IN HERTZ (Hz). IT IS USED TO DENOTE THE POTENTIAL FOR INFORMATION HANDLING CAPACITY OF THE MEDIUM, DEVICE, OR SYSTEM.
TDMM: PAGE G-18
BROADBAND CABLE
COMPOSITE BASEBAND VIDEO AND AUDIO SIGNALS THAT ARE AMPLITUDE AND FREQUENCY MODULATED, RESPECTIVELY, WITH AN RF CARRIER IN ACCORDANCE WITH THE VIDEO AND AUDIO INFORMATION THAT NEED TO BE CONVEYED (E.G., CATV).
TDMM: PAGE 1-47
CO
CENTRAL OFFICE
A COMMON CARRIER SWITCHING CENTER OFFICE (ALSO CALLED A PUBLIC EXCHANGE) THAT IS CONVIENIENTLY LOCATED IN AREAS TO SERVE SUBSCRIBER HOMES AND BUSINESSES. IT PROVIDES TELEPHONY SERVICES (LINES) THAT ARE CONNECTED ON A LOCAL LOOP. THE CO CONTAINS SWITCHING EQUIPMENT THAT CAN SWITCH CALLS LOCALLY OR TO LONG-DISTANCE CARRIER TELEPHONE OFFICES.
TDMM: PAGE G-34
CODEC
A DEVICE THAT CONVERTS SPEECH TO A DIGITAL SIGNAL AND ITS SUBSEQUENT DECODING TO SPEECH.
TDMM: PAGE 1-30
CROSSTALK
THE SIGNAL INTERFERENCE BETWEEN CABLE PAIRS, WHICH MAY BE CAUSED BY A PAIR PICKING UP UNWANTED SIGNALS FROM EITHER ADJACENT PAIRS OF CONDUCTORS OR NEARBY CABLES.
TDMM: PAGE 1-54
DECIBEL
A LOGARITHMIC UNIT OF MEASURING THE RELATIVE VOLTAGE, CURRENT, OR POWER OF A SIGNAL. ONE TENTH OF A BEL.
TDMM: PAGE G-53
DELAY SKEW
THE DIFFERENCE IN PROPOGATION DELAY BETWEEN ANY PAIRS WITHIN THE SAME CABLE SHEATH.
TDMM: PAGE 1-55
DIGITAL SIGNAL
INFORMATION USED BY THE DIGITAL DEVICES IN THE FORM OF A SEQUENCE OF DISCRETE PULSES (E.G., A BINARY SIGNAL WITH 2 VALUES USED TO TRANSMIT THE 2 STATES {0, 1}).
TDMM: PAGE 5-57
DISPERSION
- THE LOSS OF A SIGNAL RESULTING FROM THE SCATTERING OF LIGHT PULSES AS THEY ARE TRANSMITTED THROUGH A MEDIUM.
- THE WIDENING OR SPREADING OUT OF THE MODES IN A LIGHT PULSE AS IT PROGRESSES ALONG AN OPTICAL FIBER.
- THE CHARACTERISTICS OF THE SOUND COVERAGE FIELD OF A SPEAKER.
TDMM: PAGE G-60
EMI
ELECTROMAGNETIC INTERFERENCE
STRAY ELECTRICAL ENERFY RADIATED FROM ELECTRONIC EQUIPMENT AND ELECTRONICS SYSTEMS (INLCUDING CABLING).
TDMM: PAGE 1-10
FREQUENCY
THE NUMBER OF CYCLES THAT A PERIODIC SIGNAL COMPLETES IN A GIVEN TIME. IF THE UNIT OF TIME IS ONE SECOND, THE FREQUENCY IS STATED IN HERTZ (Hz). ONE Hz IS EQUAL TO ONE CYCLE PER SECOND.
TDMM: PAGE G-83
IP
INTERNET PROTOCOL
THE OPEN SYSTEMS INTERCONNECTION (OSI) REFERENCE MODEL LAYER 3 (NETWORK LAYER) PROTOCOL MOST COMMONLY USER FOR INTERNETWORKING. REQUIRED FOR COMMUNICATIONS OVER THE INTERNET.
TDMM: PAGE G-100
ISDN
INTEGRATED SERVICES DIGITAL NETWORK
A DIGITAL COMMUNICATIONS FACILITY DESIGNED TO PROVIDE TRANSPARENT END-TO-END TRANSMISSION OF VOICE, DATA, AUDIO/VIDEO AND STILL IMAGES ACROSS THE PUBLIC SWITCHED TELEPHONE NETWORK (PTSN). DIFFERENT VERSIONS AND CONFIGURATIONS EXIST REGIONALLY AND INTERNATIONALLY.
TDMM: PAGE G-98
NVP
NOMINAL VELOCITY PF PROPOGATION
THE COEFFICIENT USED TO DETERMINE THE SPEED OF TRANSMISSION ALONG A CABLE RELATIVE TO THE SPEED OF LIGHT IN A VACUUM, TYPICALLY EXPRESSED AS A PERCENTAGE. ALSO CALLED PHASE VELOCITY AND VELOCITY OF PROPOGATION.
TDMM: PAGE G-130
PCM
PULSE CODE MODULATION
A TECHNIQUE FOR REPRESENTING AN ANALOG SIGNAL AS A STRING OF BITS. THE ANALOG SIGNAL IS CONVERTED TO A BIT STRING BY PERIODICALLY SAMPLING THE AMPLITUDE OF THE ANALOG SIGNAL AND REPRESENTING EACH SAMPLE AS A BINARY NUMBER.
TDMM: PAGE G-155
PHASE
- THE RELATIONSHIP IN TIME BETWEEN 2 WAVEFORMS OF THE SAME FREQUENCY.
- THE RELATIONSHIP IN TIME BETWEEN 2 PARAMETERS OF A SINGLE WAVEFORM (E.G., VOLTAGE AND CURRENT).
TDMM: PAGE G-140
PoE
A NETWORK SUBSYSTEM THAT OFFERS THE ABILITY FOR THE LAN SWITCHING INFRASTRUCTURE TO PROVIDE POWER OVER BALANCED TWISTED-PAIR CABLING TO AN ENDPOINT DEVICE (E.G., ACCESS POINT, CAMERA, TELEPHONE SET).
TDMM: PAGE G-147
PROPOGATION DELAY
THE TIME REQUIRED FOR A SIGNAL TO TRAVEL FROM ONE END OF THE TRANSMISSION PATH TO THE OTHER END. (TIA)
TDMM: PAGE G-151
QAM
QUADRATURE AMPLITUDE MODULATION
A MEANS OF ENCODING DIGITAL INFORMATION OVER RADIO, WIRELINE, OR OPTICAL FIBER TRANSMISSION LINKS. IT IS A MODULATION TECHNIQUE THAT USES VARIATIONS IN SIGNAL AMPLITUDE AND PHASE, ALLOWING DATA ENCODED SYMBOLS TO BE REPRESENTED AS A MULTITUDE OF 2N STATES, WHERE EACH STATE ENCODES 2N BITS (E.G., 2, 4, 8, 16, 32, 64, 128, 256).
TDMM: PAGE G-155
SINUSOID
AN OSCILATING, PERIODIC SIGNAL THAT IS COMPLETELY DESCRIBED BY 3 PARAMETERS: AMPLITUDE, FREQUENCY, AND PHASE.
TDMM: PAGE 1-18
TDM
TIME DIVISION MULTIPLEXING
A PROCESS THAT COMBINES BINARY DATA FROM SEVERAL DIFFERENT SOURCES (E.G., VOICE CHANNELS) INTO A SINGLE COMPOSITE BIT STREAM.
TDMM: PAGE 1-31
WHAT IS AN ELECTRICAL CONDUCTOR?
ANY MATERIAL THAT CAN CARRY AN ELECTRIC CHARGE FROM ONE POINT TO ANOTHER
TDMM: PAGE 1-2
NAME THE 4 MOST COMMON ELECTRICAL CONDUCTORS FOR ICT WIRE AND CABLES.
- COPPER
- COPPER COVERED STEEL
- HIGH STRENGTH COPPER ALLOYS
- ALUMINUM
TDMM: PAGE 1-2
SILVER AND GOLD ARE GOOD CONDUCTORS, BUT THEY ARE NOT GENERALLY USED FOR ICT WIRES AND CABLES. WHY?
HIGH COSTS
TDMM: PAGE 1-2
WHICH CONDUCTOR SETS THE STANDARD FOR COMPARING THE CONDUCTIVITY OF OTHER METALS?
COPPER
TDMM: PAGE 1-3, TABLE 1.1
WHAT TYPE OF COPPER IS USED TO SET THE REFERENCE VALUE?
ANNEALED COPPER
TDMM: PAGE 1-3, TABLE 1.1
WHAT TYPE OF CONDUCTOR IS TYPICALLY USED FOR AEIRAL, SELF-SUPPORTING DROP WIRE?
COPPER-COVERED
TDMM: PAGE 1-3, TABLE 1.1
HOW DOS THE ALLOYING OF PURE COPPER AFFECT ITS CONDUCTIVITY?
THE ALLOYING OF PURE COPPER ALWAYS HAS ADVERSE EFFECT ON ITS CONDUCTIVITY.
TDMM: PAGE 1-3, TABLE 1.1
HOW DOES THE CONDUCTIVITY OF ALUMINUM COMPARE THE CONDUCTIVITY OF COPPER?
IT HAS ABOUT 60% CONDUCTIVITY COMPARED TO COPPER.
TDMM: PAGE 1-3, TABLE 1.1
WHAT ARE ALUMINUM CONDUCTORS COMMONLY USED?
IN ELECTRICAL UTILITY DISTRIBUTION LINES
TDMM: PAGE 1-3, TABLE 1.1
WHICH TYPE OF SOLID CONDUCTOR HAS THE POOREST CORROSION RESISTANCE?
HIGH STRENGTH ALLOY
TDMM: PAGE 1-4, TABLE 1.2
WHAT TYPE OF SOLID CONDUCTOR HAS THE POOREST OXIDATION RESISTANCE?
ALUMINUM
TDMM: PAGE 1-4, TABLE 1.2
WHICH TYPE OF SOLID CONDUCTOR HAS THE BEST TENSILE STRENGTH?
HIGHSTRENGTH ALLOY
TDMM: PAGE 1-4, TABLE 1.2
WHICH TYPE OF SOLID CONDUCTOR HAS THE BEST DUCTILITY?
HIGH STRENGTH ALLOY
TDMM: PAGE 1-4, TABLE 1,2
WHAT IS THE CONDUCTIVITY FOR A HIGH STRENGTH ALLOY CONDUCTOR?
85% OF TYPICAL
TDMM: PAGE 1-4, TABLE 1.2
HOW ARE STRANDED CONDUCTORS CREATED?
BY BUNDLING TOGETHER A NUMBER OF SMALL GUAGE SOLID CONDUCTORS TO CREATE A SINGLE, LARGER CONDUCTOR.
TDMM: PAGE 1-4
NAME 4 ADVANTAGES OF SOLID CONDUCTORS
- LESS COSTLY
- LESS COMPLEC TERMINATION SYSTEMS
- BETTER TRANSMISSION PERFORMANCE AT HIGHER FREQUENCIES
- LESS RESISTANCE.
TD,,: PAGE 1-4
NAME 3 ADVANATAGES OF STRANDED CONDUCTORS
- MORE FLEXIBLE
- LONGER FLEX LIFE
- LESS SUCCEPTIBLE TO DAMAGE DURING CRIMP TERMINATION PROCESS
WHAT IS A COMPOSITE CONDUCTOR?
A CONDUCTOR CONSTRUCTED FROM NONTRADITIONAL MATERIALS (E.G., METALLIC RESINS OR GRAPHITE)
TDMM: PAGE 1-5
NAME 5 ADVANTAGES OF COMPOSITE CONDUCTORS
- HIGHLY FLEXIBLE
- LIGHTWEIGHT
- INEXPENSIVE AND EASY TO PRODUCE
- EASILY EMBEDDED INTO OTHER MATERIALS
- LOW COEFFICIANT OF EXPANSION
NAME 4 DISADVANTAGES OF COMPOSITE CONDUCTORS
- POOR ANALOG TRANSMISSION CHARACTERISTICS INCLUDING HIGH ATTENTUATION, ESPECIALLY ABOVE 4OOO Hz
- POOR DIGITAL TRANSMISSION CHARACTERISTICS
- EASILY DAMAGED UNLESS ENCASED IN A RIGID MATERIAL
- INCONSISTENT QUALITY
TDMM: PAGE 1-5
ARE CABLES WITH COMPOSITE CONDUCTORS RECOMMENDED FOR USE WITH MODERN TELECOMMUNICATIONS NETWORKS?
NO, CABLES WITH COMPOSITE CONDUCTORS ARE NOT RECOMMENDED FOR USE WITH MODERN TELECOMMUNICATIONS NETWORKS.
TDMM: PAGE 1-5
WHY IS THE AWG SYSTEM IMPORTANT?
BECASUE IT PROVIDES A STANDARD REFERENCE FOR COMPARING VARIOUS CONDUCTOR MATERIALS
TDMM: PAGE 1-6
WHAT IS THE PURPOSE OF INSULATION ON A CABLE?
TO ISOLATE THE FLOW OF CURRENT BY PREVENTING DIRECT CONTACT BETWEEN CONDUCTORS AND A CONDUCTOR AND ITS ENVIRONMENT.
TDMM: PAGE 1-6
HOW DO DIELECTRICS REDUCE EM COUPLING BETWEEN CONDUCTORS?
BY INCREASING THE CONDUCTOR SEPARATION.
TDMM: PAGE 1-6
WHAT IS DIELECTRIC CONSTANT?
THE RATIO OF CAPACITANCE OF AN INSULATED CONDUCTOR TO THE CAPACITANCE OF THE SAME CONDUCTOR UNINSULATED IN THE AIR.
TDMM: PAGE 1-8, TABLE 1.4
WHAT DOES DIELECTRIC STRANGTH MEASURE?
THE MAXIMUM VOLTAGE THAT AN INSULATION CAN WITHSTAND WITHOUT BREAKDOWN
TDMM: 1-8, TABLE 1.4
WHAT IS DISSIPATION FACTOR?
THE RELATIVE POWER LOSS IN THE INSULATION DUE TO MOLECULAR EXCITEMENT AND SUBSEQUENT KINETIC AND THERMAL ENERGY LOSSES
TDMM: PAGE 1-8, TABLE 1.4
WHAT IS INSULATION RESISTANCE?
THE INSULATIONS ABILITY TO RESIST THE FLOW OF CURRENT THROUGH IT.
TDMM: PAGE 1-9, TABLE 1.4
HOW IS INSULATION RESISTANCE TYPICALLY EXPRESSED?
IN MEGAOHM/km OR MEGAOHM/1000 ft
TDMM: PAGE 1-8, TABLE 1.4
HOW DOES CABLE LENGTH AFFECT CABLE RESISTANCE?
AS THE CABLE LENGTH INCREASES, THE INSULATION RESISTANCE BECOMES SMALLER.
TDMM: PAGE 1-8, TABLE 1.4
WHAT IS THE MAIN REASON FOR TWISTING CONDUCTOR PAIRS?
TO MINIMIZE CROSSTALK AND NOISE BY DECRESING THE CAPACITANCE UNBALANCE AND MUTUAL INDUCTANCE COUPLING BETWEEN PAIRS.
TDMM: PAGE 1-9
WHAT DOES PAIR-TO-PAIR CAPACITANCE UNBALANCE MEASURE?
THE ELECTRIC FIELD COUPLING BETWEEN TWO PAIRS IF A DIFFERENTIAL VOLTAGE IS APPLIED ON ONE PAIR AND A DIFFERENTIAL NOISE VOLTAGE IS MEASURED ON ANOTHER PAIR IN CLOSE PROXIMITY.
TDMM: PAGE 1-9
WHAT IS MUTUAL INDUCTANCE?
A MEASURE OF THE MAGNETIC FIELD COUPLING BETWEEN TWO PAIRS IF A DIFFERENTIAL CURRENT IS APPLIED ON ONE PAIR AND A DIFFERENTIAL NOISE CURRENT IS MEASURE ON ANOTHER PAIR IN CLOSE PROXIMITY
TDMM: PAGE 1-9
HOW IS CROSSTALK WITHIN A MULTIPAIR CABLE MINIMIZED?
BY GIVING EACH PAIR A DIFFERENT TWIST LENGTH WITHIN A STANDARD RANGE
TDMM: PAGE 1-9
WHAT YPE OF TWIST IS GENERALLY USED FOR VOICE AND LOW-FREQUENCY CABLES?
A COUNTERCLOCKWISE TWIST LENGTH BETWEEN 50mm AND 150mm (1.97” AND 6”)
TDMM: PAGE 1-9
WHAT IS TIGHT TWISTING?
CREATING PAIR TWIST LENGTHS THAT ARE LESS THAN 12.7mm (.5”)
TDMM: PAGE 1-9
WHERE IS TIGHT TWISTING COMMONLY USED?
WITHIN AND BETWEEN COMPUTERS AND OTHER DATA PROCESSING EQUIPMENT.
TDMM: PAGE 1-9
WHICH CABLE CATEGORIES EMPLOY TIGHT TWISTING FOR OPTIMUM TRANSMISSION PERFORMACE?
CATEGOR 5e, 6, 6A AND HIGHER
TDMM: PAGE 1-9
WHAT TERM IS USED TO REFER TO STRAY ELECTRICAL RADIATED FROM EQUIPMENT AND ELECTRONIC SYSTEMS?
ELECTROMAGNETIC INTERFERENCE (EMI)
TDMM: PAGE 1-10
AT WHAT TEMPERATURE DOES ATTENTUATION INCREASE IN BALANCED TWISTED-PAIR CABLES?
ABOVE 20°C (68°F)
TDMM: PAGE 1-10
WHAT TEMPERATURE REFERENCE IS CITED IN CABLING STANDARDS FOR ALL TWISTED-PAIR CABLES?
20°C +/- 3°C (68°F +/- 5.4°F)
TDMM: PAGE 1-10
WHAT IS A CABLE SHIELD?
A METALLIC COVERING OR ENVELOPE ENCLOSING AN INSULATED CONDUCTOR, INDIVISUAL GROUP OF CONDUCTORS WITHIN A CORE, AND CABLE CORE.
TDMM: PAGE 1-13
NAME 3 POTENTIAL BENEFITS OF USING A CABLE SHIELD IF IT IS PROPERLY TERMINATED, BONDED AND GROUNDED.
- REDUCES THE RADIATED SIGNAL FROM THE CABLE.
- REDUCES THE EFFECTS OF ELECTRICAL HAZARDS.
- MINIMIZES THE EFFECT OF EXTERNAL EMI ON THE CONDUCTORS WITHIN THE SHIELDED CABLE.
TDMM: PAGE 1-13
NAME 3 FACTORS THAT CAN AFFECT A SHIELD’S EFFECTIVENESS.
- TYPE AND THINCKNESS OF THE SHIELD MATERIAL.
- NUMBER AND SIZE OF OPENINGS IN THE SHIELD.
- EFFECTIVENESS OF THE BONDING CONNECTION TO GROUND.
TDMM: PAGE 1-13
HOW IS THE SHIELD EFFECTIVENESS DETERMINED?
BY MEASURING THE SURFACE TRANSFER IMPEDANCE.
TDMM: PAGE 1-13
WHAT IS SURFACE TRANSFER IMPEDANCE?
THE RATIO OF THE CONDUCTOR-TO-SHIELD VOLTAGE PER UNIT LENGTH TO THE SHIELD CURRENT.
TDMM: PAGE 1-13
WHY ARE SOLID METAL TUBES INAPPROPRIATE FOR MOST CABLE APPLICATIONS?
BECAUSE OF THE RIGID NATURE
TDMM: PAGE 1-14