Modern Building Systems Flashcards
What is Structured Cabling?
Telecommunications wiring in buldings
What was structured cabling originally?
Plain Old Telephone Service (POTS)
What does structured cabling include?
- Telephone/fax
- Television
- Video
- Security
- HVAC
- Automation
What is the connection point called where electricians take over the wiring?
Demarcation
Also known as Network Interface Device, Node zero, and Telco Room
What are the 4 networks?
- Internet Service Provider (ISP)
- Wide Area Network (WAN)
- Local Area Network (LAN)
- Municipal Area Network (MAN)
What does a municipal area network for?
Civil (sewer and water) and emergency services
What is ISP wiring typically provided by?
twisted pair, coax, fibre or a combination
What may Node Zero include?
modems (modulator, demodulator), routers, splitters, switches (data), cross connects (punch down blocks), control panels, radios
What can LAN wiring include?
twisted pair, coax or fibre (even power wiring) but generally refers to CAT5e, CAT 6, CAT6a, U.T.P.
What is “convergence” refer to?
the integration of various media (voice, video, data) onto common medium (U.T.P., coax, fibre)
What are the 3 types of twisted pair wiring? What do they carry?
- Unshielded twisted pair (U.T.P.)
- Shielded twisted pair (S.T.P.) - each indiv. pair is shielded
- Screened twisted pair (Sc.T.P.) - all pairs have overall shield
They carry “balanced” signals with half the signal on each conductor
Are signals out of phase?
yes, by 180°
What are the 4 components of a coaxial cable?
- Core
- Dielectric (insulation)
- Shield
- Jacket
How is the signal carried in a coaxial cable? How is the shield bonded?
- the entire signal is carried on the center core
- shield is bonded at both ends
What is the purpose of the shield in a coaxial cable?
reduce outside signals from ingressing onto the core, and provides a return path for the signal
How is a quad shield shielded?
foil, braid, foil, braid for improved shielding
What are the core materials used, for what purposes and at what Hz?
Solid Copper (usually) - closed circuit TV (CCTV) and audio and video signals (approx 5-55 MHz) Copper Claded Steel - community antenna TV (CATV), satellite TV (950-1450 MHZ)
What does the core gauge depend on?
Frequencies and Distance required
cable specific connectors are required based on what?
- Radio Grade
- Shielding Configuration
- Jacketing
- Characteristic Impedance
What does the dielectric insulation between the core and shield determine?
the “characteristic impedance” of the cable with its capacitance
Does the length of the cable have affect on its impedance?
NO
What is the impedance dependant on?
Frequency dependant and varying slightly over the intended frequency range
What must have the same characteristic impedance? What will occur if they do not?
All components (transmitters, splitters, cable, connectors, receivers) or else losses will occur (reflected signal cancelling out the main signal)
What are typically ohms of Radio Transmitters, data modems (coax) and CATV systems?
Radio transmitters and data modems = 52 or 50 ohms
CATV systems = 75 ohms
The impedance of a cable is severely affected by any disturbance of the dielectric. List some examples of what could do this?
- A kink in a coax renders it destroyed
- Excessive pulling tension
Max 80 lbs for good RG-6
Max 25 lbs for CAT5e
The shield may be what in coaxial cable? What do double shielded cables have?
- Braided 92% copper or tinned copper
- Foil 100%
Double shielded cables have both
What are Baluns?
- balanced to unbalanced matching transformers
- HDMI extenders are sometimes called baluns
Coax connectors are labelled as what?
“F” connectors
Coax couplings are labelled as what?
“F-81” connectors
What are the two standards for Twisted Pair Balanced Systems? What do they specify? (EIA & TIA)
- Electronics Industry Association
- Telecommunications Industry Association
They specify the “category” of cabling
What is Power Over Ethernet?
44 - 57 Vdc (48V nominal) over our ethernet cabling
Power over Ethernet switches and routers or power inserting equipment are used for what?
- Phones
- Cameras
- Tstats
- Remote data switches
What are U.T.P. connectors called?
Registered Jack
What are the properties of RJ 11 U.T.P.s?
6 pole 4 conductor bus paralleled
What are the properties of RJ 12 U.T.P.s?
6 pole 4 conductor straight thru (no sharing)
What are the properties of Ethernet RJ 45s?
8 pole 8 conductor
Explain Simplex Communication systems?
- Info is sent in 1 direction only
- Source to receiver
- ex: broadcast radio
Explain Half Duplex Communication systems?
- Info is sent in both directions but only 1 at a time
- each direction shares a common channel
- ex: Two-way radios
Explain Full Duplex Communication systems?
- Info is sent in both directions at same time
- Two channels required, 1 for each direction
- ex: Telephone system
What is a Decibel (dB) ?
a ratio with a logarithmic (exponential) scale. Sound level, voltage and power levels are often compared using dB’s
What is Thermal Noise? (atmospheric noise, cable noise, receiver noise)
Random electron movement thru any conductive materials with ohms creates random voltages at random frequencies
What is thermal noise directly proportional to?
Temperature and has a flat frequency response
All frequencies with equal amplitude = ?
White noise
Explain Slope?
In regards to frequency response, all cables will have more attenuation (losses) at higher frequencies
What do some amplifiers have to compensate and provide more gain at higher frequencies?
Slope Adjustment
What is Signal to Noise ratio?
the ratio in dB of signal to noise
What must analog systems have in regards to Signal to Noise?
Signal to noise ratio must be very good or noise is noticeable
Explain signal to noise ratio in digital systems
Signal to Noise ratio can be lower because the receiver need only determine 1s and 0s
What does a very poor SNR result in?
High bit error rate (BER) and causes signal dropouts/pixelation
What are splitters/combiners?
Coax (unbalanced) signals are split into multiple receivers (transmitters can be combined thru the same units)
What power would you expect for a 1 into 2 splitter?
1/2 power to each outlet
What should you do if using a splitter with more outlets than required?
- Terminate unused outlets with a 75 ohm termination
What is automatic gain control?
Receivers have automatically adjustable amplifiers in their circuitry to compensate for reasonable variances in signal power
What will happen if you add a splitter to an automatic gain control?
AGC will increase
What will happen if you amplify the signal in automatic gain control?
AGC will decrease
What must automatic gain control systems be ‘balanced’ with? Why?
Must be balanced with amplifiers or power continuation devices (PADs) to supply signal strength towards the center of the AGC range
What are the 6 types of physical topologies?
- Linear Bus
- Star Network
- Ring
- Tree
- Mesh
- Hybrid
Linear Bus Advantages and Disadvantages?
Adv: Easily disconnect nodes without disrupting service
DIsadv: Not reliable if trunk cable is down everyone is down
Star Network Adv. & disadv. ?
Adv: Easy to add additional devices with no service interruption
Disadv: Hub represents a single point of failure, not reliable
Ring Adv & Disadv?
Adv: performs better under heavy network load & server does not need to manage connectivity to each device
Disadv: 1 bad workstation & system is down. Making any changes will affect network operation
Tree Adv & Disadv?
Adv: easy to add more nodes, reliable network and some level of redundancy with multiple servers
Disadv: overall length of each segment limited to 100m, more difficult to wire than other topologies
Mesh Disadv ?
Expensive to have this if it is a physical connection
What is a hybrid topology?
a combination of two or more topologies
What are the two types of protocol?
- Ethernet
2. Token Ring
What are some advantages of Fibre Cable?
- Operate at high speeds
- Large carry capacity
- Signals can be transferred further
- Immune to RFI & EMI
- Light weight
- Costs much less to maintain
What are single-mode characteristics?
- Narrow Core
- Higher bandwidth for long distances
- More expensive than multi-mode and more difficult to terminate
- 5.8 micron glass core
- Uses lasers
Multi-mode characteristics?
- Wider core or more fibres
- Higher bandwidth for shorter distances
- In long runs, multiple light pulses (modes) can distort and deliver incomplete data
- 60 micron glass core
- uses LEDs
25 Pair cable colour codes:
5 Tip colours : White, red, black, yellow, violet
5 Ring colours: blue orange green brown slate (grey)
What is I.D.C. and what is it considered?
Insulation Displacement Connector
Considered gas proof
What are normal voltages for POTS?
On hook = 48 VDC
Off hook = approx. 9 VDC
Ringing = approx. 90-110 VAC
How many cables max for velcro straps? Why?
15-20 to avoid crosstalk
Tips for using conduit?
- 100’ max between pull points
- Two 90° bends between pull points
- Ream Conduit
- Insulated bushings
- Must have pull strings or ropes
- 40% fill max
- Firestop may be required
Cable tray tips:
- 50% max fill
- Access important, 1’ above required
- Metal trays bonded to ground
Cable placement tips:
- 25 lbs-ft max
- Bend radius = 10x diameter multipair, 4x diameter horizontal
- 3” from power sources
- leave 18” at outlets and connection points
What are the types of punchdown blocks?
- 66 type
- 110 type
- BIX type
How much should you untwist conductors for cat5e and cat6?
1/2” max for cat5e
1/4” max for cat6
what is the most popular punchdown block?
110 type
What block is used when space is an issue?
BIX type
What is BLOGB?
colour identification for 8 conductor cable
Blue, Orange, Green, Brown
What is Permanent Link testing?
(basic link) cable run from cross-connect or patch panel to work area outlet
What is Channel Testing?
tests not only the cable, but all hardware, patch cords, cross-connect wiring, etc..
Explain Certification testing for length? What test tool is used?
- 568 cables must be less than 90m in link and 100m in channel
- Done with a “time Domain Reflectometer”
- Tester sends out a pulse, waits for an echo and measures the time it took for the trip
Explain an Attentuation test?
measures the signal loss from one end of the link to the other, the smaller the dB the better
Explain a crosstalk test?
- Measured at both ends (NEXT & FEXT), larger the dB the better
What is crosstalk? What helps prevent this?
- Unplanned transfer of data from one pair to another
- twist rates help prevent within cable
- shielding helps prevent between cables
What is Attentuation to Crosstalk ratio?
measurement of how much more signal than noise exists in the link
larger the dB the better
What is some essential info for cabling install?
- Plans
- Entrance facilities
- Equipment rooms
- Telecom closets
- Telecom equipment
- Spaces and pathways
- Work area outlets
What division are telecom specs in?
16 and possibly 17
When should conduit be used?
- When required by code
- If outlet boxes are permanent
- Cable security required
What is an Inner/Subduct?
Non-metallic pathway within a pathway
What are some types of cable trays?
- Ladder cable tray
- Basket tray
- Rollout tray
What are some underfloor systems?
- Underfloor duct embedded in concrete
- Cellular floor
- Raised access floor
- Ceiling pathway
What are some methods of supporting cables?
- J-hook
- Plywood backboards
- Tywraps
- Velcro
What connector does LAN use?
BNC (bayonet mount)
In power of ethernet, what is the max amps per conductor?
1.3A
what is PSE?
Power sourcing equipment
what is PD?
Powered device
What are the 5 purposes of Security systems?
- Deterrence
- Prevention
- Detection
- Response
- Apprehension
What are the 3 categories of the Onion Skin Approach of security and their properties?
- Perimeter Protection - Door contacts, Beam break
- Space Protection - Motion detectors, the “back-up”
- Spot Protection - Last line of protection, placed around the object (lock)
What does Power over Ethernet allow?
Allows appliances to receive power as well as data over existing LAN cabling
What is Central Equipment in Nurse Calls? what does it house?
Brain of the system
Houses programming and cct boards, power supplies and terminal blocks
What is the Dome light?
Visual annunciation just outside the room requiring assistance
What is a zone lamp?
in hallway to direct nurse to room requiring assistance
What are the different priority levels and their properties?
High = Flashing red or blue, 60 PPM, code blue Medium = Flashing white, 30 PPM, toilet shower etc.. Low = Steady white, 6 PPM with tone every 10s, patient station
What are some different kinds of detectors for security?
- Magnetic Contacts
- Passive Infrared
- Microwave Detectors
- Dual Tech Devices
- Photoelectric Beam detectors
- Glass breaks
- Shock sensors
What are the two styles Magnetic Contacts come in?
- Surface mount and Recessed
What are some advantages and disadvantages or PIRs?
- Very versatile
- Quad element PIR will eliminate false alarms
- Has hazards for false alarms such as heaters, reflective glass, sources of whitelight
Advantages and Disadvantages of Microwave Detectors?
Advantages: - sense motion towards the detector - longer range than PIR - Unaffected by ambient conditions Disadvantages: - Subject to interference from other microwaves - sensitive to flouresent lights - Must adjust range so they dont look for movement outside
Explain Dual Tech detectors?
- rely on two sensing methods
- Majority Microwave/PIR
What is the most common intrusion circuit?
closed loop
What type of supervision does the closed-loop provide?
open-circuit supervision
What happens if the loop is shorted in a closed loop application?
it will not detect an alarm as the contacts have been bypassed
what are the 4 basic closed-loop circuits?
- Two-wire
- two-wire with EOL
- Four wire
- Four wire ULC
What is commonly used in lower security applications such as residential alarms? Why?
Two-wire as it provides only partial supervision and are easily defeated
What is popular in higher-security applications such as commercial buildings?
Two-wire with EOL
What is the four-wire loop also called?
double circuit or HI/LO loop
How are the loops wired and is there current in its secure position? When is the four-wire loop most used?
HI loop is +
LO loop is -
no current flow in secure position
Most used in installations using window foil
What is the four-wire ULC recognized as and by who?
High-level security by the Underwriters Laboratories of Canada
What must the contacts be in a four-wire ULC system?
must be Form C which = SPDT, with N.O. and N.C. contacts
