CM1481 Datasheet, PDF (17/24 Pages) ON Semiconductor – 2-Channel EMI Filter with ESD Protection for Headsets/Speakers

Functional Descriptions
‘Muted’ Call
Initiation
It is possible for the CM1481 to be embodied within a radio that has no local means of
Quiet/Open control; the CM1481 will be configured to Dual button operation but the Quiet/
Open input not used. Such a system will require the base station to operate its mute
system and open the squelch or re-mute with a Remote Reset command.
In a radio that has no local means of opening its mute function, the operator must initiate a
Selcall to the base; PTT Lockout will prevent any illegal voice transmission.
The base must be so configured as to contact the CM1481 fitted radio and lift the mute
function (and therefore allow normal operation) by replying with the unit's Receive Address.
Reception of its receive address Selcall will cause an alert beep sequence at the CM1481;
operation of the PTT will halt the alert and unmute the radio; normal operation may take
place.
Upon completion of the conversation the unit's operation will be reset (muted) by the base
with a Remote Reset command.
Configured as Call When Quiet:
Power-Up
'Quiet'/'Open'
The CM1481 can be configured to assume one of two mutes conditions upon power-up.
Quiet -- The audio output is muted; a Quiet/Open operation is required to monitor
channel activity.
Open -- The audio output is active; the channel can be monitored to ascertain activity
and correct operation.
Configured as Start-Up State:
Over-Air
Functions
(a) Remote Reset
(b) ‘Re-Configuration’ (c) ‘Stun’
(d) ‘Release’
The above operations may be carried out from a suitably configured remote station (the
controlling base) to:
(a) Mute a Radio:
Using a “C” or “D” tone appended to the units Rx Selcall address. See Figure 13.
(b) ‘Re-Configure’ the following parameters:
Tx Address
Rx Address
ANI Address
ANI Mode
Transpond Address
Transpond Mode
(c) ‘Stun’ a Radio:
To completely disable a CM1481 fitted radio unit.
Rx audio is permanently muted; PTT line is disabled; Selcall transmission is inhibited.
(d) ‘Release’ a Radio:
To release the CM1481 fitted radio from the ‘Stun’ mode and allow normal operation.
Over-Air function operation is enabled and disabled at Configuration as Over-Air Function:
17