Motorola Gm300 Selling Manual

Transmit Features2-13
A“Re-Key inhibit duration” can be programmed, which prevents users from re-transmitting a
period of time after the TOT has expired. This prevents an individual user from “hogging” the
channel.
A“De-Key Telegram on TOT”can be programmed to send a telegram when the radio times out.
Benefits

Enforces efficient use of airtime.

Addresses accidental continuous keying.

Re-Key Timer stops users hogging the channel.
6.2 Transmit Admit Criteria
Transmit Admit Criteria automatically check...

2-14FEATURES AND BENEFITS
Carrier Gone Timer Expired– This option only allows transmission when carrier has not been
detected for a programmable period of time.
This option is used to prevent operators currently not involved in calls, transmitting over other users
who may be active on the channel, but are de-keyed with their auto-reset timers running.
PL/DPL Not Detected– This option only allows transmissions when carrier is not present, or
when carrier is present and the radio is not currently detecting...

Squelch Features2-15
6.2.2 Channel Free Beep
If a transmission attempt fails due to Transmit Admit Criteria not being satisfied, a Channel Free
Beep is sounded as soon as the criteria are satisfied.
Benefits

User is advised as soon as they are permitted to transmit; particularly useful on a busy
channel.

Message can be sent as soon as possible.

Don’thavetowastetimere-tryingtotransmit.
7.0 Squelch Features
7.1 Receive Squelch Mode
Squelch settings are used to keep the radio’s loudspeaker turned off...

2-16FEATURES AND BENEFITS
7.2.2 PL Reverse Burst / DPL TOC
A Reverse Burst or Turn Off Code (TOC) can be generated when the PTT is released on a channel
transmitting PL/DPL (respectively). It is sent to indicate the end of transmission to the receiving
radio and so reduce squelch tail.
These are the equivalent of 5 tone Cleardown / Remote Close calls.
Benefits

Different groups in an organization can share a channel

Users dont hear the communications of other groups
7.3 Monitor
Monitor allows the normal...

Squelch Features2-17
7.3.2 Forced Monitor on PTT (Smart PTT)
It is good radio practice to monitor the channel before transmitting. Forced monitor on PTT enforces
this. The first press of the PTT or a call button puts the radio in monitor mode. The second press of
the PTT or call button actually make the radio transmit. This is Forced Monitor ‘Always’.
Forced Monitor ‘Only if Channel Busy’ is aSmart PTT. It only enters monitor mode if there is
channel activity; if there is no channel activity the radio is...

2-18FEATURES AND BENEFITS
8.0 Accessory Connector
8.1 Dealer Programmable I/O Features
All models of the GM300 Series Professional mobile radios incorporate a dealer programmable
accessory connector as standard.
There are: 4 input lines,
1 output line, and
3 input / output (I/O) lines.
Ta b l e 2 - 3Accessory Connector I/O Features
Pin number
34689101214GM950
External Output Functions:
Carrier Detect 

Ye s
PL/DPL DetectYe s
Radio Busy

Ye s
External AlarmYe s
Per Channel Output

Ye s...

Accessory Connector2-19
Each programmable pin can be disabled or programmed to a feature. The active state of each pin
can be set as high or low: except

emergency is active low;

ignition is active high.
Benefits

Enables interface to a wide range of external devices.

Customer specific applications can be catered for.

Gives excellent oppor tunities for enhanced dealer added value.

Interface to external Mobile Data Modems.Ta b l e 2 - 4Accessory Connector Pin Out
PinFunction
1Speaker -
2ExternalMic...

2-20FEATURES AND BENEFITS
8.2 Output Functions
8.2.1 Carrier Detect
The output is asserted whenever carrier is detected and is de-asserted if no carrier is present.
The output is de-asserted if the radio is in TX mode.
8.2.2 PL/DPL Detect
The output is asserted whenever the correct PL is detected.
If PL override is disabled, the output is de-asserted when the correct PL is lost.
If PL override is enabled, the output remains asserted for the AutoReset time after the correct PL is
lost. This is...

Accessory Connector2-21
8.2.5 Per Channel Output
The output is asserted when the radio is on a channel that has Per Channel Output enabled,
otherwise the output is de-asser ted.
This is used to drive any device which is channel usage specific.
8.2.6 Car Radio Mute
This option is used to mute the audio on a car’s hi-fi system when the two way radio is in use.
The output is asserted if the radio’s loudspeaker is open or the radio is transmitting.
The output is de-asserted if the radio’s loudspeaker has...

2-22FEATURES AND BENEFITS
8.2.8 Decoder Output Control
The output is asserted by the successful decode of a decoder that has Assert Output Control
enabled.
It is de-asserted by the successful decode of a decoder that has De-assert Output Control enabled.
This option is enabled/disabled per personality. This function can be useful for simple telemetry
applications.
Benefits

Allows remote control of external device.

When used in conjunction with external call switch, gives simple telemetry.
8.3 Input...