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Functional Description
When in the Knocked-Down mode, the only transmission possible will be using wireline PTT
commands, ie: No Repeater Function.
Type 3 Repeater
The repeater is programmed using the RSS to be permanently in Set-Up mode and may be Enabled
by valid audio.
1.1.8
Line Fail Talkthrough (LFTT)
If Line Fail Talkthrough has been selected via the RSS, the TRICK will monitor the wireline for
activity. If a TRC guard tone is not received before the LFTT Timer expires, the wireline is assumed
to have failed. The LFTT Timer is reset on receiving a guard tone.
If the wireline fails, the Repeater will revert to unconditional repeater operation. In this mode, the
repeater will remain in permanent Set-Up and will be Enabled on receiving valid audio.
The duration of the LFTT Timer is defined using the RSS.
The wireline will be considered to be restored when a TRC command has been received by the
TRICK. The repeater will switch back to its original mode of operation once the wireline has been
restored.
Line Fail Talkthrough ensures that the repeater is available to mobile/portable users even if the
wireline consoles are off-line and unable to activate it.
1.1.9
Repeater Time Out Timer
The transmitter Time Out Timer (TOT) is used to monitor the duration of the transmission period. The
maximum value of this timer is programmed into the TRICK using the RSS.
Each time the TRICK keys up (enables) the TX radio, the TOT will start. If the TOT reaches the
programmed maximum value, the TX radio is de-keyed (disabled).
The programmable range of this timer is 0 to 240 seconds.
The implementation of this timer provides discipline to the system by preventing a single call from
blocking other calls for an unacceptable time period.
1.1.10
Repeater Block Timer
The Re-key Timer is used for setting a time limit before the next transmission can take place after
the TOT has expired. The duration of the Re-key timer is programmable using the RSS.
If the TOT expires and the Re-key Timer is selected, the TX radio cannot be re-keyed by any new
valid condition for the duration of the Re-key Timer.
If the Re-Key Timer is NOT selected, the TX radio may be re-keyed any time after the expiration of
the TOT from the previous call.
The programmable range of this timer is 0 to 15 seconds.
As with the Transmitter Timeout Timer, this timer provides system discipline by preventing individual
users from monopolising airtime.
1-6
Functional Description & Applications
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