Dc Remote Current Detection; Receive Audio - Motorola MSF 5000 Instruction Manual

MSF
5000
Instruction Manual
Chapter 1 Description
TTRC
Audio Board
ALC
Control Description
NOTE
To
bypass
the
ALC
control circuit, place jumper
JU4230 in
the alternate position.
This
requires
a
fixed
level of
the
HLGT
at -12.5 42.5 dBm for proper
operation.
The
ALC
circuit
is
controlled
by
the
microprocessor
during
tone detection and
execution of wireline commands. The
ALC
adjusts the level of audio to meet the
initial
HLGT
input level.
Tone Processing Section
The
ALC
audio from TP5
enters the tone processing section and is bandpass
filtered
at the
guard
tone frequency of 2175
Hz.
After
the
HLGT
detection, the bandpass filter is bypassed
to
allow detection of
function
tones
which usually
are
in
the
range of
650
Hz
to 2050
Hz.
Detection is
accomplished in
the microprocessor on the
TTRC
Logic
board.
A
bandpass
filter/limiter attenuates
signals outside of
the
software detector range, and
transforms the tone signals into digital signals.
The output (TP3 on the
TTRC
Audio
board) is
a
square
wave which is
sent into
the microprocessor for
analysis.
DC Remote Current Detection
The function currents sent from
a
remote
device down
the
wireline
are
converted
to
DC
voltage levels by two optical isolators and their
associated circuitry. One
detects positive line currents;
the other detects
negative line currents. Both
provide electrical isolation between
the
wireline and
other
circuitry
on the
TTRC
Audio
board
to
protect the circuits against
lightning
or
high voltage surges.
Figure
1-13
shows
a
block diagram
of the
DC
remote control circuitry.
Receive Audio
The Receive
Audio circuitry
is responsible for transferring
LINE AUDIO
from the
SSCB
to the
wireline
on
Line
2
or
Line
4.
The circuitry consists of
a
receive notch
filter,
summing and level adjust circuits,
Cca
Spectra-TAC™ equalizer
filter, line
drivers, and wireline
interfaces.
Figure
1-14
shows
a
block diagram of
the receive
audio circuitry.
68P81092E02
3/19/94
1-31
MSF
5000
Instruction Manual
Chapter 1 Description
TTRC
Audio Board
ALC
Control Description
NOTE
To
bypass
the
ALC
control circuit, place jumper
JU4230 in
the alternate position.
This
requires
a
fixed
level of
the
HLGT
at -12.5 42.5 dBm for proper
operation.
The
ALC
circuit
is
controlled
by
the
microprocessor
during
tone detection and
execution of wireline commands. The
ALC
adjusts the level of audio to meet the
initial
HLGT
input level.
Tone Processing Section
The
ALC
audio from TP5
enters the tone processing section and is bandpass
filtered
at the
guard
tone frequency of 2175
Hz.
After
the
HLGT
detection, the bandpass filter is bypassed
to
allow detection of
function
tones
which usually
are
in
the
range of
650
Hz
to 2050
Hz.
Detection is
accomplished in
the microprocessor on the
TTRC
Logic
board.
A
bandpass
filter/limiter attenuates
signals outside of
the
software detector range, and
transforms the tone signals into digital signals.
The output (TP3 on the
TTRC
Audio
board) is
a
square
wave which is
sent into
the microprocessor for
analysis.
DC Remote Current Detection
The function currents sent from
a
remote
device down
the
wireline
are
converted
to
DC
voltage levels by two optical isolators and their
associated circuitry. One
detects positive line currents;
the other detects
negative line currents. Both
provide electrical isolation between
the
wireline and
other
circuitry
on the
TTRC
Audio
board
to
protect the circuits against
lightning
or
high voltage surges.
Figure
1-13
shows
a
block diagram
of the
DC
remote control circuitry.
Receive Audio
The Receive
Audio circuitry
is responsible for transferring
LINE AUDIO
from the
SSCB
to the
wireline
on
Line
2
or
Line
4.
The circuitry consists of
a
receive notch
filter,
summing and level adjust circuits,
Cca
Spectra-TAC™ equalizer
filter, line
drivers, and wireline
interfaces.
Figure
1-14
shows
a
block diagram of
the receive
audio circuitry.
68P81092E02
3/19/94
1-31