Motorola APX 7500, Detailed Service Manual

Page: 90 / 164

September 9, 2011 68009482001
4-20 Feature Operation: APCO Interface
4.16 APCO Interface
The Consolette supports the APCO Interface.
Table 4-7. Signals Table
One application of using the APCO interface, is the support of external MDC encoders/decoders.
• MDC Encoders - Consolettes can be connected to an external MDC encoder. Encoders are
typically used to generate tones that are provided to the Consolette via the audio connection for
transmit over the air. An associated Push-to-Talk signal is also provided to key up the
Consolette.
• MDC Decoders - Consolettes can be connected to an external MDC decoder. Tones are
received over the air by the Consolette and provided on the receive audio path on its rear
panel.
NOTE: The auxiliary (APCO) PTT input is mutually exclusive with the Crosspatch CP_PTT*. As a
result, when Crosspatch is enabled, the APCO PTT is disabled and A(tx) is no longer routed.
4.17 Over-the-air Alert Tones Operation (L999_ required)
Over-the-air alert tones allow the Consolette operator to advise a fielded subscriber of a critical
communication. The Consolette supports this functionality from its front panel. There are three
predefined alert tones that can be assigned to either the softmenus underneath the auxiliary display
or to the dedicated programmable buttons.
The predefined alert tones are:
• Alert 1 sends a 1 kilohertz tone
Function
Pin
Abbreviation
Definition
Transmit
Audio A(tx) This is an unbalanced low level transmit audio input relative to
ground. The input sensitivity is 300mVrms nominal for 60%
rated transmit system deviation.
Receive
Audio A(rx) This is an unbalanced receive audio output relative to ground.
The output is 300mVrms nominal for 60% rated receive system
deviation. This output is muted when there is not valid audio
present.
Push-to-Talk PTT This is a logic input to cause the radio to transmit. The radio will
transmit when this input is pulled to less than 0.8VDC to
ground.
Qualified
Audio
Presence A(p) This signal is the output of an onboard
relay(CHAN_ACT_RELAY_OUT). Its level is what is applied to
the relay input(CHAN_ACT_RELAY_IN). The normally open
relay is activated/closed when there is valid receive audio
present.
Note: This output is not a simple carrier detect output. It cannot
be used as a “Channel Busy” indication.
Monitor Monitor This is a logic input to cause the Consolette to toggle the
Monitor state of the radio. The radio will monitor the selected
channel (override PL) when this input is pulled to less than
0.8VDC to ground. This input is combined with all other active
sources of Monitor and HUB within the Consolette.