CM1481 Datasheet, PDF (12/24 Pages) ON Semiconductor – 2-Channel EMI Filter with ESD Protection for Headsets/Speakers

Functional Descriptions
Receive Call
Operation
Individual Selcall Receive Sequence
Unit’s Rx Selcall Address is decoded
Alert cancelled by ’blip’ of PTT, Call
or Quiet/Open buttons, or Time-Out
i If Transpond configured the unit transponds
ii Audio Open; "Open" Alert is output
iii "Call Received" Alert is output; LED output is pulsed
i Alert beeps stop
Conversation takes place; Conversation complete
Radio is muted by: push-button/Timed Mute Reset
/Remote Reset
i Unit "Closed" Alert is output. Radio is Closed.
GROUP Selcall Receive Sequence
A GROUP-call with the unit’s Rx Selcall
Address is decoded
i No transpond can take place for a GROUP-Call
ii "GROUP-Call" Alert is output; this alert is self cancelling
The calling party transmits the message/s
The CM1481 can only reply to an originator whose Tx Address is
configured, and not to the other GROUP members - Conversation complete.
Radio is Closed by: push-button/Timed Mute Reset
/Remote Reset
i Unit "Closed" Alert is output. Radio is Closed.
Fig.5 Rx Call Operation
Transmit Call
Operation
Normall Selcall Transmit Sequence
Unmute the radio by push-button operation -
(see Single/DualButton operation)
- or employ ’Muted Call’ initiation Method
i Unit "Open" Alert is output.
ii Radio squelch circuitry released to normal operation
Monitor the channel.
Transmit the (Tx Address) Selcall by push-button
operation
Note that if the BUSY input is active, a call
cannot be transmitted (PTT Lockout)
i "Call Transmitted" Alert is output
ii Tx ON is active; the Selcall is output at TONE OUT
A If the system is ’No Transpond’, when the called station’s reply is received the converstaion may continue.
B If the system is ’Transpond’, await the transpond action then conversation may continue.
Start Conversation
i PTT Timer started
Conversation complete
Radio is Closed by: push-button/Timed Mute Reset
/Remote Reset
i Unit "Closed" Alert is output. Radio is Closed.
Fig.6 Tx Call Operation
LED Drive
A polarity programmable LED drive output is available if a visual indication of a received
Selcall is required. It is recommended that, under LED conditions, this output is configured
as an “active high” and an external LED is connected directly to GND (0V).
With due regard to the specified current limits, this output may be used to activate mobile
horn-honk/indicator driver circuits.
LED Call
Memory
If the ‘Selcall Received Alert’ has been activated but not cancelled, the module can be
configured so as to leave the LED illuminated as a Call Memory.
The use of any push-button function will cancel this LED action.
Configured as LED Call Memory:
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