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NewS
tream
User Guide and Technical Manual
Term
Defi nition
Roll-off [Continued]
The concept of roll-off stems from the fact that in many networks roll-off
tends towards a constant gradient at frequencies well away from the cut-off
point of the frequency curve. Roll-off enables the cut-off performance of such
a
fi
lter network to be reduced to a single number. Note that roll-off can occur
with decreasing frequency as well as increasing frequency, depending on the
band form of the
fi
lter being considered. For instance, a low-pass
fi
lter will
roll-off with increasing frequency, but a high-pass
fi
lter or the lower stop band
of a band-pass
fi
lter, will roll-off with decreasing frequency.
RSSI
Receiver Signal Strength Indicator [relative]
This parameter provides each cellular card’s or Wi-Fi Access Point’s RSSI.
The RSSI is the relative received signal strength in arbitrary units. RSSI is an
indication of the power level being received by the antenna. The higher the
RSSI number, the stronger the signal.
SCM-Q
Superposition Coded Modulation - Quadrature
SCM-Q is a modulation scheme designed to use the bandwidth ef
fi
cient
codec, such as H.264, enabling the transfer of the same video quality at up
to twice the distance, with a greatly improved Peak-to-Average-Power-Ratio
[PAPR]. SCM-Q has variable bandwidth so can also be used for channel
sharing.
SDI
Serial Digital Interface
A serial communications interface operating at 270 Mbit/sec. SDI can
operate at 1.5 Gbit/sec for HD.
SIM Card
Subscriber Identity Module Card
A SIM is an integrated circuit that stores the International Mobile Subscriber
Identity [IMSI] and key used to identify and authenticate subscribers on
mobile telephony devices. A SIM card contains:
•
its unique serial number [ICC ID]
•
International Mobile Subscriber Identity [IMSI]
•
security authentication and ciphering information
•
temporary information related to the local network
•
a list of the services the user has access to
•
two passwords: a personal identi
fi
cation number [PIN] for ordinary
use and a personal unblocking code [PUK] for PIN unlocking
The primary advantage of cellular wireless data is that you have access
to the Internet from any location, indoors or outdoors, throughout your
carrier’s data coverage area. A disadvantage – as is prevalent with cellular
telephones – is that cellular coverage can be attenuated indoors, as well as
in remote areas.
SMPTE
Society of Motion Picture and Television Engineers
SNR
Signal-to-Noise Ratio
A measure of signal strength and quality that is de
fi
ned as the ratio of the
amplitude of a signal compared to the amplitude of the background noise.
SNR is typically measured in decibels [dB].
