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The PTT Watchdog allows the user to set the maximum transmit time. This is used to protect against a
„stuck‟ transmitter. The time is selected by a slider bar. The range is 0 to 120 seconds with a default of 30
seconds. Warning: Transmissions longer than 30 seconds may exceed the duty cycle rating of the
transmitter
and lead to shortened life or transmitter failure. A factory-installed cooling fan is available for extended
duty operations. For continuous-transmit applications, the PTT Watchdog feature can be disabled
(unchecked).
Synthesizer
This field lists the synthesizer model used. This field is non-selectable and for reference only.
Dynamic Carrier Detect Off Threshold
The Dynamic Carrier Detect Off Threshold allows the modem to automatically adjust the Carrier Detect
Off Threshold based on the RSSI while receiving data. If selected, the Carrier Detect Off level will
automatically adjust to approximately 15 dB below the actual signal strength. This provides rapid
detection
of loss-of-carrier and minimizes or eliminates „bit dribble‟ at the end of transmissions.
Recommendation: Keep Dynamic Carrier Detect Off Threshold enabled (checked) unless interference or
variable signal strength (i.e., fading in a moving vehicle) causes problems.
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Carrier Detect On Threshold
Carrier Detect On Threshold indicates RSSI level when a carrier is found. This level should be more than
the Carrier Detect Off Threshold.
Carrier Detect Off Threshold
Carrier Detect Off Threshold indicates the RSSI level when a carrier is lost. This level should be less than
the Carrier Detect On.
2.5.4.5 Setup Modem/Radio Frequencies
The Frequencies tab provides the interface to program frequency pairs and their corresponding power
settings.
Figure 2-12 Setup Radio/Modem Frequencies Parameters
