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Ericsson DIALOG - Automatic Transmission Regulation Explained

Ericsson DIALOG
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Fig. 32 Tlze
circuit
diagram
of
Dialog
4.
DESCRIPTION OF
THE
TRANSMISSION
REGULATION DEVICE
DIALOG
is
provided
with
an
automatic
sensitivity
control
also
called
automatic
transmission
regulator.
The
function
of
this
device
is
to
limit
the
sending
and
receiving
transmission
level
when
the
local
line
is
decreased
and
improve
it
when
the
local
line
is
increased.
The
result
is
that
the
transmission
level,
within
certain
limits.
will
be
almost
constant
and
independent
of
the
length
of
the
subscriber's
line.
Receiving
regulation
is
about
4 dB.
which
means
that
receiving
is
attenuated
with
4 dB
on
a 0 Ohm
line
compared
to
what
it
would
have
been
without
regulation.
The
purpose
of
regulation
is
that
the
signal
picked
up
by
the
ear
shall
have
the
same
level
independent
of
the
length
of
the
local
line
up
to
1 000
aim.
line
attenuation
included.
This
means
that
the
signal
will
be
heard
equally
well
when
the
instrument
is
con-
nected
to
the
exchange
on
a
short
line
as
on a long
line.
For
the
subscriber
telephoning,
this
is
particularly
pleasant
and
for
the
total
transmission.
advantageous.
The
reasons
for
regulating
the
transmission
level
at
sending
are
as
follows:
Prolonged
life
of
the
transmitter
The
basic
principle
here
is
that
the
current
through
the
trans-
mitter
shall
always
be
constant.
independent
of
the
length
of
the
line.
This
is
achieved
with
a
nonlinear
element
varistor
V2,
the
conductance
of
which
increases
with
the
voltage
drop
across
it,
connected
in
parallel
with
the
transmitter.
When
the
voltage
across
the
transmitter
and
the
non-linear
element
increases,
as
a
result
of
reduced
length
of
line,
the
conductance
of
the
element
increases.
In
this
way
the
unnecessary
part
of
the
feeding
current
for
the
transmitter
is
shunted
away
from
the
transmitter.
Long-line
efficiency
The
instrument
is
designed
as
to
give
its
optimal
efficiency
on
the
long-line
-
just
where
it
is
most
needed.
It
has
high
transmitter
effect
for
line
resistances
of 1 500 Ohm.
The
receiving
regulation
device
operates
as
follows.
The
symbols
used
refer
to
fig. 32.
IC
C
Copac1/or
IC
Induction
coit
H
Hicrophone
R
Receiver
r2-r5
Resistors
VI-
V2
Voris/ors
VJ
Shock
ohsor6er
21
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