3 terminology: functions, names & acronyms – Media Technology Systems ION8.8 User Manual
Page 7
Page 7 of 31
Aug‐09
1.3 Terminology: Functions, Names & Acronyms.
Attenuation/Attenuator:
An attenuator is used to reduce the level of an incoming
signal.
Many
think
the
"volume"
control
on
typical
audio
equipment
makes
the
power
of
the
amplifier
greater.
In
fact
amplifiers
are
typically
pre‐set
with
a
specific
amount
of
gain.
The
input
attenuator
or
volume
control
is
used
to
vary
the
amount
of
signal
that
is
allowed
through
to
the
amplifier's
gain
section.
BGM Back Ground Music
: Typically low‐level ambient music such as one would find
in an elevator or super‐market.
CMRR
: Common Mode Rejection Ratio, is the ability for an input circuit to reject noise
interference and other artifacts induced on the input signal lines. A balanced line, or
differential
input
has
two,
opposite
and
equal,
plus
and
minus,
input
connections
and
a
centre
ground
reference.
The
cable
has
two
conductors
and
a
shield
or
ground
connection.
At
the
transmit/send/source
end
of
the
cable
the
audio
signal
is
split
and
one
side
is
inverted
in
phase.
Over
a
run
of
cable
any
hum,
buzz
or
other
electromagnetic
inference,
not
effectively
shielded
b
y
the
cable
is
picked
up
and
theoretically
induced
equally
on
both
the
plus
and
minus
conductors.
Thus
we
have
the
intended
signal
running
out‐of‐phase
and
any
induced
noise
running
in‐phase
across
the
two
conductors.
These
opposite
and
equal
signals
are
brought
into
a
differential
amplifier
where
the
phase
of
one
of
the
signal
that
was
in
inverted
is
put
back
into
phase
and
the
two
signals
added
together.
The
signals
since
they
are
complementary
add
together.
The
noise
which
was
in
phase
is
inverted
added
together
but
now
out
of
phase
and
thus
cancelled.
The
instrumental
Instrumentation
input
is
of
the
highest
quality
where
the
circuits
and
values
of
the
components
are
closely
matched.
The
more
closely
matched
the
two
sides
of
the
input
are
the
greater
the
ability
of
the
circuit
to
reject
and
common
mode
signals.
CobraNet™
®
: CobraNet™ is a proprietary digital audio networking protocol designed
for high quality, low latency digital audio transmission.
http://www.CobraNet™.info/en/
Euroblock
: The ‘Phoenix/Euroblock’ ‐type connector is a pair of high current, latching,
output
connectors
used
for
speaker
and
70/100V
Line
loads.
Rated
at
300V/15A
these
connectors
are
reliable,
of
high
quality,
and
simple
to
install
and
re‐configure.
LAN Local Area Network
: A digital network normally using CAT‐5/RJ‐45 or WiFi
connectivity
for
routing
data,
and
digital
audio
and
video
signals
Latency:
Effectively the time delay between a signal being sent and received through a
system,
typically
caused
by
signal
processing
and
network
transmission
time.
Low
latency
is
considered
in
the
2ms
to
12ms
range.
Above
the
12ms
latency
the
delay
between
an
original
signal
and
the
reproduced
signal
becomes
perceptible
and
detracts
from
the
intelligibility
of
the
communication.
Note:
In
paging
applications
latency
is
not
an
issue
since
there
is
rarely
"open‐microphone"
use
as
in
entertainment
or
other
"Live"
uses.