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responds to an active RX2 ACT by gating deemphasized,
PL-stripped
audio from the second receiver to the RX2
audio line. From there, it is mixed with line audio (out-
bound wireline) by the station control module. RX2 Au-
dio is also mixed with select audio (local speaker) by the
station control module.
4.13 RX1 ACT (RECEIVER
1 ACTMTY)
2, DO
The RXI ACT bit indicates whether the primary receiver
has audio present with the proper qualifiers to unmute re-
ceiver audio. This condition is set for each channel by four
qualifiers in the station control module code plug. These
qualifiers determine
what combination
of the four MUX-
bus bits RX PL DS, Rl PL DT, Rl UN SQ, and AUX DET
are ANDed to obtain RXI ACf. The station control mod-
ule responds to an active RXI ACT by opening the RXI
audio gate. This gates RXI audio to both the line audio
(outbound wireline) and select audio (local speaker) lines.
RXI audio is also gated to the station control module re-
peater audio gate. If the station is transmitting
due to a
RPT PTT, then the repeater
audio gate will be open and
RXI audio will be gated, via the IDC circuit, to the TX
modulation
audio line.
4.14 RX PL DS (RECEIVE PLIDPL
DISABLE) 3, D3
The RX PL DS bit causes the station to revert to carrier
squelch only operation for purposes of determining
status
of RXI ACT and RX2 ACf. The Monitor and Receiver
Squelch OnlOff
wireline functions
utilize RX PL DS.
Also, the station control module front panel PL Disable
switch activates RX PL DS.
4.15 Rl PL DT (RECEIVER 1 PLlDPL
DETECT) 3, D2
The Rl PL DT bit is active when PL or DPL coded
squelch is being detected via Receiver 1.
4.16 Rl SQ LV (RECEIVER 1 SQUELCH LEVEL) 3,
nt
The R
1
SQ LV bit changes the carrier squelch threshold.
When Rl SQ LV is active, the primary receiver is operat-
ing with "loose" squelch.
4.17 Rl UN SQ (RECEIVER
1 UNSQUELCH)
3, DO
The Rl UN SQ bit is a status only bit, and is active when
the Receiver
1
audio carrier squelch circuit on the station
control module detects activity. Rl UN SQ is used for au-
dio gating (refer to RX 1ACT), not for repeater
keying
(refer to RPT
PIT).
4.18 R2 MUTE (RECEIVER 2 MUTE) 4, D3
The R2 MUfE
bit causes the second receiver control
module to attenuate
the audio driving the RX2 audio line,
so that Local or RXI audio can be heard on both the line
7/15/90
68P81114E03
audio (outbound
wireline) and select audio (local speak-
er) lines. The attenuation
is accomplished
by means of a
potentiometer
on the second receiver control module.
Therefore,
RX2 audio can be fully muted, if desired.
4.19 R2 PL DT (RECEIVER 2 PLlDPL
DETECT) 4, D2
The R2 PL DT is active when PL or DPL coded squelch
is being detected via Receiver 2.
4.20 R2 SQ LV (RECEIVER 2 SQUELCH LEVEL) 4, D1
The R2 SQ LV bit changes the carrier squelch threshold.
When R2 SQ LV is active, the second receiver is operat-
ing with "loose" squelch.
4.21 R2 UN SQ (RECEIVER 2 UNSQUELCH)
4, DO
The R2 UN SQ bit is a status only bit, and is active when
the Receiver 2 audio carrier squelch circuit on the second
receiver control module detects activity. R2 UN SQ is
used for audio gating (refer to RX2 ACT). The second re-
ceiver can neither key the repeater
(activate RPT
PIT),
nor modulate
the transmitter.
4.22 GD TN DT (GUARD TONE DETECT) 5, D3
The GD TN DT bit becomes active whenever high level
guard tone is detected from the TX Audio signal (inbound
wireline) by the tone remote control module. In stations
with an antenna
switch, the station control module re-
sponds to an active GD TN DT by switching the antenna
switch to its transmit state. The TX Audio signal is muted
(on the station control module) while GD TN DT is ac-
tive, in order to prevent remote control tones from being
transmitted.
4.23 AUX DET (AUXILIARY DETECT) 5, D2
The AUX DET bit indicates that an optional decoder is
detecting. The optional decoder may be connected
to ei-
ther Receiver
1
or Receiver 2 audio. AUX DET can be
used to activate TXl ACT , RX2 ACT, and RPT
PIT
in
a manner similar to the Rl PL DT and Rl UN SQ qualifi-
ers.
4.24 RPT KD (REPEATER
KNOCK-DOWN)
5, Dl
The RPT KD bit disallows a repeater
PTT. Also, this bit
forces an existing active RPT
PIT
inactive.
4.25 RPT USQ (REPEATER
UN SQUELCH)
5, DO
The RPT USQ bit is a status only bit, and
is
active when
the Receiver
1
repeater carrier squelch circuit, located on
the station control module,
detects
activity. This bit
is
used to key the repeater,
not to gate audio (refer to RPT
PTT).
7
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