Squelch Circuitry - Motorola MSF 5000 Instruction Manual

MSF
5000
Instruction Manual
Chapter 1 Description
Squelch Circuitry
FROM RX
PROCESSING
AMP
CIRCUIT
SSCB
Functlonal Description
The squelch circuitry responds
to the
signal (noise level) strength of the
incoming
receive audio. The squelch detectors drive
control lines to the control and
logic
circuitry, which
are
used in key-up and gating arbitration.
The QUAD AUDIO signal
from the output of the QUAD
1
audio buffer is routed
to
a
noise amplifier that boosts the noise content of the input signals above
5
kHz.
The
noise amplifier
limits
the
audio signals
to
provide protection against audio
signals squelching
the receiver.
The output of the noise amplifier drives both
the
receiver and
the repeater squelch detectors. Refer to
Figure
1-8
for a
block
diagram of
the squelch circuitry.
TO CONTROL
AND LOGIC
FROM CONTROL
AND LOGIC
TO CONTROL
AND LOGIC
RECEIVER SQUELCH
QUAD AUDIO
NOISE
EEPOT
#3
AUDIO
FRONT PANEL
GATE SQUELCH KNOB
RX! UNSQ
RECEIVER
CHAN
ACT
SQUELCH
DETECTOR
CONTROL LINES
REPEATER
SQUELCH
LEVEL ADJUST
REPEATER
RPTR
UNSQ
SQUELCH
DETECTOR
EEPOT
#2
ADJUST
MSFI071
020794JNM
Figure
1-8 Squelch Circuitry
68P81092E02
3/19/94
Receiver/Repeater Squelch Circuitry
For
the receiver squelch
circuitry,
EEPOT
3
(receiver squelch level adjust) is
adjusted
to gate the
audio for processing. For
the repeater squelch
circuitry,
EEPOT
2
(repeater squelch
level adjust) is adjusted to activate the repeater
PTT.
The squelch knob on the front panel of the Control Tray adjusts
the
local speaker
squelch only.
1-19
MSF
5000
Instruction Manual
Chapter 1 Description
Squelch Circuitry
FROM RX
PROCESSING
AMP
CIRCUIT
SSCB
Functlonal Description
The squelch circuitry responds
to the
signal (noise level) strength of the
incoming
receive audio. The squelch detectors drive
control lines to the control and
logic
circuitry, which
are
used in key-up and gating arbitration.
The QUAD AUDIO signal
from the output of the QUAD
1
audio buffer is routed
to
a
noise amplifier that boosts the noise content of the input signals above
5
kHz.
The
noise amplifier
limits
the
audio signals
to
provide protection against audio
signals squelching
the receiver.
The output of the noise amplifier drives both
the
receiver and
the repeater squelch detectors. Refer to
Figure
1-8
for a
block
diagram of
the squelch circuitry.
TO CONTROL
AND LOGIC
FROM CONTROL
AND LOGIC
TO CONTROL
AND LOGIC
RECEIVER SQUELCH
QUAD AUDIO
NOISE
EEPOT
#3
AUDIO
FRONT PANEL
GATE SQUELCH KNOB
RX! UNSQ
RECEIVER
CHAN
ACT
SQUELCH
DETECTOR
CONTROL LINES
REPEATER
SQUELCH
LEVEL ADJUST
REPEATER
RPTR
UNSQ
SQUELCH
DETECTOR
EEPOT
#2
ADJUST
MSFI071
020794JNM
Figure
1-8 Squelch Circuitry
68P81092E02
3/19/94
Receiver/Repeater Squelch Circuitry
For
the receiver squelch
circuitry,
EEPOT
3
(receiver squelch level adjust) is
adjusted
to gate the
audio for processing. For
the repeater squelch
circuitry,
EEPOT
2
(repeater squelch
level adjust) is adjusted to activate the repeater
PTT.
The squelch knob on the front panel of the Control Tray adjusts
the
local speaker
squelch only.
1-19