Section 3. Operation
3-5
Privacy Mode
Finally, the Model 38 checks to see if the user is set for “Privacy Mode”. If enabled,
then no other users (CTCSS or DCS) will be allowed on the system until the transmit
hold time has expired. This feature can prevent other user groups from “barging in”
on the conversation and taking over control of the repeater.
Airtime Accumulation
The Model 38 keeps track of the airtime used by each customer group on the channel. Both
enabled and disabled users are logged. The airtime is stored in “hours:minutes:seconds”
format and will hold up to 250 hours per user. The airtime counts may be retrieved over the
channel or via the RS-232 port. The airtime may be set to accumulate including or excluding
the repeater transmit hold time (see programming section).
Repeater Hold Time
The programmable repeater transmit hold timer is adjustable from 0.0 to 9.9 seconds. When a
mobile unkeys, the Model 38 will begin monitoring for a valid CTCSS tone or DCS code to
be received again. If a valid user is not detected within a timeout period, a reverse burst for
CTCSS or digital turn-off code will be sent then the encode will be turned off (if it was
previously on). After a 0.2 second delay, the transmitter PTT will be dropped. This method
will remove the second squelch tail heard by the mobiles when the repeater transmitter
unkeys. Repeater “tailbips” may be enabled to beep once every second during the repeater
hold time.
Timeout Timer
While mobiles are conversing through the repeater, a timeout timer is running. If a mobile
does not un-key within the timeout period, warning tones will be sent, and then the
transmitter PTT will be dropped. This is a “stuck mic” time-out feature.
Timeout User Identification
After a timeout occurs, the system may be set to transpond (via slow DTMF) the user number
of the mobile that is still keyed up. The repeater will key up every 15 seconds while the
mobile is transmitting and send the user number. This feature can be enabled or disabled by
the system manager.
DTMF Regeneration
The Model 38 may be used to regenerate DTMF tones over the radio channel for applications
involving mobile DTMF decoders or control station telephone interconnects (such as Zetron
Models 30 or 45). DTMF regeneration ensures that all DTMF signaling occurs at the same
tone level. DTMF regeneration can occur for any or all users. A user commands the repeater
to regenerate DTMF digits by sending a DTMF “*” for greater than 1 second. When the digit
is released, the Model 38 squelches the repeat audio and begins regenerating all DTMF tones
received from the user until no digit has been received for the interdigit timeout
(programmable; factory set at 4 seconds). All sixteen DTMF tones can be regenerated.
