what enables set-top boxes (STB) and data over cable service interface
specification (DOCSIS) modems to operate as completely separate systems
that operate independent of each other? - correct answers STB and DOCSIS
modems are assigned different upstream channels with different upstream
channels with dedicated receivers in the headend
what did the 1.1 version of DOCSIS introduce, incorporating solutions for
transporting real-time data applications (such as voice traffic) over the cable
operators managed IP network, and doing so with quality comparable to the
telephone company - correct answers PacketCable
why is 38 MHZ typically the highest frequency in the sub-brand frequency that
8s used for upstream modem transmissions? - correct answers the upper
edge of the sub-frequency spectrum is prone to group delay caused by the
duplex filters
what enables the set-top box (STB) upstream carrier to be located below 20
MHz and still be reliably received? - correct answers the narrow bandwidth
and quadrature phase shift keying (QPSK) modulation
what system is a byproduct of the "funneling effect" ? - correct answers a
many-to-one system
house amplifiers with a passive return path are used for what type of
situation? - correct answers for situations when long service drops are used
and the forward path needs to be amplified but return path amplification is
unnecessary
,why does output level from customer premises equipment (CPE) vary? -
correct answers to compensate for variable amounts of attenuation in the
return path of each device
when calculating return path attenuation in the drop system, what is the
attenuation loss through the hot-leg of an unbalanced three-way splitter at
sub-split frequencies? - correct answers 3.5 dB
what purpose do duplex filters fulfill when installed at the input and output of a
two-way amplifier module? - correct answers to route the forward and return
signals over different circuit paths to the appropriate section so that they can
be amplified separately
how does the signal attenuation through coaxial cable in the sub-brand
frequency spectrum compare to the attenuation at forward path frequencies? -
correct answers at sub-band frequencies, the signal attenuation is significantly
less than in the forward path
which optical band is used for optical amplifiers due to the attenuation loss
and availability of economical optical fibers? - correct answers the c band
what is the one limitation of fabry-Perot (fp) lasers that is eliminated in
distributed feedback (DFB) lasers? - correct answers side modes
in what applications are avalanche photodiodes (APD) most likely to be used?
- correct answers in fiber-to-the-home (FTTH) architectures where high
attenuation of optical splitters must be overcome
why is the E band undefined for fiber-optics communications? - correct
answers there is a lot of older fiber-cable still in use that may have
unacceptable water-peak attenuation
, in the traditional analog return path, what is critical about the upstream optical
transmitter? - correct answers to make RF level into the upstream transmitter
is correct
in a traditional analog return, the optical dectors are responsive to the power
of the recieved signal. how does the signal level at the output of the upstream
recicer relate to changes to its input power? - correct answers the signal level
at the output of the upstream receiver changes 2 db for every 1 db of received
optical power level
why is using dBmV, a voltage measurement, acceptable to express the power
per Hz power allocation across the channel bandwidth? - correct answers
because a constant 75-ohm impedance is being used
when aligning the optical return path, what are the ideal characteristics of the
test signal injected into the upstream optical transmitter? - correct answers a
noise signal of the same bandwidth to be used for upstream transport
what evolved after the introduction of switched digital video (SDV) illustrated
some limitations of legacy hybrid fiber coax (HFC) networks? - correct
answers distributed access architecture (DAA)
what is it necessary in the optical return path to get the most performance
from the DOCSIS 3.1 specification? - correct answers some combination of
higher transmit power, more sensitive receivers, and lower path loss
which type of digital modulation contains 4 symbols with 2 bits in each
symbol? - correct answers quadrature phase shift key (QPSK)