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58 Cards in this Set

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_________ results from the fact that the speed of a signal through a medium is diffrent for diffrent frequencies.
delay distortion
_______ occurs when the signal meets an obstical and some of the signal reflects.
Return loss
In this technique the sender generates a pseudorandom sequence of numbers that dictate which frequencies will be used and the order in which they are used.
Frequency Hopping Spread Spectrum.
Why is fiber immune to noise.
because it uses light instead of electrical current
________ when signals travel through multiple pairs of wire and the speed varies from wire to wire.
Delay skew
BNC T-connector is used for _____?
coax
High frequency radio transmissions can do what?
carry a higher data rate than low frequency
____ is only suitable for low speeds because the receiver must re-tune itself every time the frequency changes.
FHSS
The ___ regulates the wireless frequency spectrum in the United States.
FCC
__________ frequency can go through walls easy.
Low
When a wireless signal reflects off an object and multiple copies of the same signal arive at the receiver it is called ___________?
multipath
Approxmatily there are _______ frequencies in the radio spectrum but not all are usable for communication.
300 million
Name the 3 types of wired media.
1 Coax
2 Twisted pair
3 Fiber optics
Compents in the atmoshpere like water and oxygen absorb wireless signals, this is called _______?
atmospereric absorption
Wireless transmission can suffer from five main impairments.
1 free-space loss
2 atmosphere absorption
3 multipath
4 refraction
5 thermal noise
Is higher or lower frequencies effected more by atmospheric absorption?
high
This impairment deals with wireless signals dispersing over distance.
Free-space loss
Name some disadvanteages of coax cable.
1 more expensive and thicker than twisted pair
2 stiff and hard to work with
3connectors are more prone to failure
Plastic fibers can be used for ________ ________ only.
short distances
Fiber is made of ________ or _________.
glass or plastic
The more twists in a twisted pair means it is more immune from ______.
noise
name the two damaging effects caused by multipath.
1 Since the receiver will receive to copies of the same signal they will interfere with each other
2 receiver might get multiple copies of the same signal
Fiber can send transmission in haow many directions?
one
Name five major transmission impairments for copper and fiber optic media.
1 Attebuation
2 Delay distortion
3 noise
4 return loss
5 delay skew
Multipath is a big problem with _______.
cell phones
What are the two types of light sources used with fiber.
LED and laser
_________ is a problem with satelite signals due to their weak signals.
Thermal noise
The __connector is the most common type of fiber connector used today.
ST
Are short wave or long wave lasers more common.
Shortwave lasers are more common...the are similar to those in cd players
LEDs are used for _____.
low speed applications (10-100Mbps).
SC and ST connectors are used for?
fiber
Excessive bending and pulling and compression can increase _________.
crosstalk
___________ works by combining the signal with a pseudo-random sequence that serves to spread the signal accross the entire spectrum at once.
Direct Sequence Spread Spectrum
Thermal noise is also called _______ noise.
white.
______________ is used when wire media will not work. ie across cities or a nation via satelites.
microwave
Name the three bands used for commercial satelites.
C
Ku
Ka
_________ results from the thermal agitation of electrons.
Thermal noise
_______ is the result of unwanted electrical signals.
Noise
Electromagnetic interference or radio frequency interference causes _____ noise?
impulse
_______ is the bending of radio waves due to atmospheric conditions.
refraction
_____ is caused by signals in adjacent wires.
Crosstalk
RJ-45 connectors are used with ____?
UTP
What causes impulse noise?
Electromagnetic interference or radio frequency interference.
On the surface of the earth maximum distance between microwave antennas is ________ because of the curvature of the earth.
30 miles
Lightning causes _____ noise.
impulse
An ___________ signal spreads out in all directions and can be received by many antennas spread around the transmitting antenna.
omnidirectional
Wire spices, imperfections in the cable and the cable connectors are examples of what causes _________.
return loss
Describe Geostationary eath orbit (GEO)
orbits at 22,300 miles above earth. Matches the rotation on earth and appears to be statioanry in the sky.
Name the three main types of wireless media.
1 Microwave
2 Radio
3 Infrared
Medium earth orbit (MEO)
orbits 6K - 12K miles up. only "visible" for 2-4 hours each orbit.
Microwaves uses frequencies between ____ and _____GHz.
2 and 40
Name the four parts to a coax cable
1 Outer jacket
2 sheilding
3 dielectric insulation
4 conductor
Current minimum standard for twisted pair is __________.
Cat5E
Two techniques to implement spread spectrum.
DSSS and FHSS
Long wavelengths =
Long distances
How are wireless transmissions and receptions accomplished?
With antennas
Low earth orbit (LEO).
Orbits 500-1000 miles up and is the fastest of the three categories. Only visible for 15 minutes each orbit.
A ___________ signal is a narrow focused bean that requires the sending and receiving antennas to be carefully aligned.
directional